faster than light travel
Anthony Potts
On Wed, 19 Jun 1996, Sandro Gisler wrote:
> History shows that:
>
> Science considered speed of over 30 kph would be deadly for the human body...
> Until the railroad was invented.
>
That is not true.
> Science considered moving faster than acoustic waves would be impossible for mankind...
> Until the jet plane was invented.
>
That is not true.
> Science considered moving faster than light would be impossible for any matter...
> Until ... I don't know either, but remember that although our race is gathering knowledge
> faster than ever before, we don't know yet everything!
>
Please, you will have to try harder than that.
Anthony Potts
CERN, Geneva
Guido Wuyts
OK, let's have a try.
If you visualise the world line of a faster than light particle in a
Minkowsky diagram you will notice
that it would coincide with the space axis of some inertial system. This
implies that in one particular
inertial system such a particle would actually have to appear as an
instantaneous, one moment phenomenon.
I myself like to picture mass as a concatenation of light clocks, i.e. a
web of radiation that goes to and fro within
a tiny volume that could be associated with this moving mass. Now, this
description by itself seems to be
indifferent whether you evolve it along a time-like axis (where it would
describe subluminal mass) or
along a space-like (where it would describe a tachyon).
There are some snags however. Firstly, as you leave a one-dimensional
space-description for a two- or three-
dimensional one, you realise that there is no symmetry when reverting
the roles between one time-axis
and three space axes. So the objects described would certainly differ
highly in nature.
Secondly, there is the phenomenon of phase correlation, that would apply
to any pair of e.g. photons having
been "together" somewhere "in the past". The light clock concatenation
process that would go with ordinary
matter ensures conservation of this phase correlation between any
succession of a c "coming" and "going"
photon. But the process covering tachyons would have to cope with, from
our point of view, the meeting
between two uncorrelated photons (or light cones), in alternation with
the departure of two correlated ones. So
this concatenation would not transmit phase correlation. A good reason
perhaps for considering tachyons as an
impossibility.
As an interested layman about physics I came across many questions
during my reading, for whose answer I am
looking for a forum. Would this be the right place or does anyone have a
better suggestion?
Jacob
In article <Pine.GSO.3.95a.970401143646.19042T-100000@cms2>, Anthony Potts
<po...@cms.cern.ch> wrote:
-)On Wed, 19 Jun 1996, Sandro Gisler wrote:
-)
-)> History shows that:
-)>
-)> Science considered speed of over 30 kph would be deadly for the human
body...
-)> Until the railroad was invented.
-)>
-)
-)That is not true.
Incorrect answer! It is true!
-)
-)> Science considered moving faster than acoustic waves would be
impossible for mankind...
-)> Until the jet plane was invented.
-)>
-)That is not true.
Incorrect answer! It is true!
-)
-)
-)> Science considered moving faster than light would be impossible for
any matter...
-)> Until ... I don't know either, but remember that although our race is
gathering knowledge
-)> faster than ever before, we don't know yet everything!
-)>
-)Please, you will have to try harder than that.
-)
-)
-)Anthony Potts
-)
-)CERN, Geneva
William L. Bahn
Jacob <jal...@hub.ofthe.net> wrote in article
<jallen-0104...@lbb58.ofthe.net>...
> In article <Pine.GSO.3.95a.970401143646.19042T-100000@cms2>, Anthony
Potts
> <po...@cms.cern.ch> wrote:
>
> -)On Wed, 19 Jun 1996, Sandro Gisler wrote:
> -)
> -)> History shows that:
> -)>
> -)> Science considered speed of over 30 kph would be deadly for the human
> body...
> -)> Until the railroad was invented.
> -)>
> -)
> -)That is not true.
>
> Incorrect answer! It is true!
>
30kph is 18.6mph - Some men can run faster than that over short distances!
Horses can certainly run faster than that (it's only a 3:21 minute mile).
Do you claim that neither of these feats had been observed before the
railroad was invented? Hardly likely.
>
> -)
> -)> Science considered moving faster than acoustic waves would be
> impossible for mankind...
> -)> Until the jet plane was invented.
> -)>
> -)That is not true.
>
> Incorrect answer! It is true!
>
Most rifle bullets, many handgun bullets, nearly all artillery shells and
even the ballistic rockets such as the Congreve rockets used in the War of
1812 and referred to in the American National Anthem (rocket's red glare?)
were supersonic. People were fully aware of the speeds of these objects. Do
you maintain that science claimed that the existence of such things was
impossible until the jet plane was invented? Again, I hardly think so.
>
> -)
> -)
> -)> Science considered moving faster than light would be impossible for
> any matter...
> -)> Until ... I don't know either, but remember that although our race is
> gathering knowledge
> -)> faster than ever before, we don't know yet everything!
> -)>
There undoubtedly were many people who believed the things you claim, but
*science* did not maintain them. Some scientists doubted if control of
flight could be maintained while passing through the transonic flight
regime (i.e., the *sound barrier*), but I am aware of none that claimed
supersonic travel was physically impossible. I'm sure you can find all
kinds of Hollywood movies that say otherwise, but please remember that
movies are notorious (now as well as then) for never accurately depicting
scientific issues even when that is what they claim to be doing.
Instead of saying, * Incorrect answer! It is true! *, please provide
details on where we can go to verify that *science* maintained these
things.
> -)Please, you will have to try harder than that.
> -)
> -)
> -)Anthony Potts
> -)
> -)CERN, Geneva
Agreed....MUCH HARDER!
Kelvin
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It would certainly help if you quoted where the heck you people got your
information so others can look up your so-called 'facts'.
Jacob <jal...@hub.ofthe.net> wrote in article
<jallen-0104...@lbb58.ofthe.net>...
> In article <Pine.GSO.3.95a.970401143646.19042T-100000@cms2>, Anthony
Potts
> <po...@cms.cern.ch> wrote:
>
> -)On Wed, 19 Jun 1996, Sandro Gisler wrote:
> -)
> -)> History shows that:
> -)>
> -)> Science considered speed of over 30 kph would be deadly for the human
> body...
> -)> Until the railroad was invented.
> -)>
> -)
> -)That is not true.
>
> Incorrect answer! It is true!
>
>
> -)
> -)> Science considered moving faster than acoustic waves would be
> impossible for mankind...
> -)> Until the jet plane was invented.
> -)>
> -)That is not true.
>
> Incorrect answer! It is true!
>
>
> -)
> -)
> -)> Science considered moving faster than light would be impossible for
> any matter...
> -)> Until ... I don't know either, but remember that although our race is
> gathering knowledge
> -)> faster than ever before, we don't know yet everything!
> -)>
> -)Please, you will have to try harder than that.
> -)
> -)
> -)Anthony Potts
> -)
> -)CERN, Geneva
>
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<html><head></head><BODY bgcolor=3D"#FFFFFF"><p><font size=3D1 =
color=3D"#000000" face=3D"Verdana">It would certainly help if you quoted =
where the heck you people got your information so others can look up =
your so-called 'facts'.<br><br><br><br>Jacob <<font =
color=3D"#0000FF"><u>jal...@hub.ofthe.net</u><font =
color=3D"#000000">> wrote in article <<font =
color=3D"#0000FF"><u>jallen-0104...@lbb58.ofthe.net</u><font =
color=3D"#000000">>...<br>> In article <<font =
color=3D"#0000FF"><u>Pine.GSO.3.95a.970401143646.19042T-100000@cms2</u><f=
ont color=3D"#000000">>, Anthony Potts<br>> <<font =
color=3D"#0000FF"><u>po...@cms.cern.ch</u><font color=3D"#000000">> =
wrote:<br>> <br>> -)On Wed, 19 Jun 1996, Sandro Gisler =
wrote:<br>> -)<br>> -)> History shows that:<br>> -)> =
<br>> -)> Science considered speed of over 30 kph would be deadly =
for the human<br>> body...<br>> -)> Until the railroad was =
invented.<br>> -)> <br>> -)<br>> -)That is not true.<br>> =
<br>> Incorrect answer! It is true!<br>> <br>> <br>> =
-)<br>> -)> Science considered moving faster than acoustic waves =
would be<br>> impossible for mankind...<br>> -)> Until the jet =
plane was invented.<br>> -)> <br>> -)That is not true.<br>> =
<br>> Incorrect answer! It is true!<br>> <br>> <br>> =
-)<br>> -)<br>> -)> Science considered moving faster than light =
would be impossible for<br>> any matter...<br>> -)> Until ... I =
don't know either, but remember that although our race is<br>> =
gathering knowledge<br>> -)> faster than ever before, we don't =
know yet everything!<br>> -)> <br>> -)Please, you will have to =
try harder than that.<br>> -)<br>> -)<br>> -)Anthony =
Potts<br>> -)<br>> -)CERN, Geneva<br>> </p>
</font></font></font></font></font></font></font></font></font></body></h=
tml>
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Alan Kohler
In article <Pine.GSO.3.95a.970401143646.19042T-100000@cms2>, po...@cms.cern.ch
says...
>
>On Wed, 19 Jun 1996, Sandro Gisler wrote:
>
>>
>> Science considered speed of over 30 kph would be deadly for the human
body...
>>
>
I think that I'm going to have to toss in with the first poster and say: That
certainly is true. It was commonly beleieved at the time that if a man
travelled that fast, he would lose his breath and die.
But I will say that such a notion was certainly less scientifically founded
than relativity, but relativity itself suggests ways of circumventing a
distance (namely wormholes), in effect allowing FTL travel. (Also, there is
the theory of tachyons, but that's been discussed here before, so I won't
expound).
Generally speaking, assuming that we "know everything there is to know" about
a given subject is scientifically speaking, naive. At the end of the 19th
century, physics professors encouraged students not to venture further into
science, as it was beleived that everything that needed known about physics
was known. However, since then, there have been numerous developments - such
as relativity and quantum mechanics.
--
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Alan D Kohler hwk...@REMOVE2REPLYpoky.srv.net
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is greater, for each violation."
Patrick van Esch
Anthony Potts (po...@cms.cern.ch) wrote:
: On Wed, 19 Jun 1996, Sandro Gisler wrote:
: > History shows that:
: >
: > Science considered speed of over 30 kph would be deadly for the human body...
: > Until the railroad was invented.
: >
: That is not true.
It is true if you replace "science" by "some peasants" :-)
: > Science considered moving faster than acoustic waves would be impossible for mankind...
: > Until the jet plane was invented.
: >
: That is not true.
This is a myth indeed. What *is* true is that many aircraft engineers
considered the task of making such an airplane challenging. What is also
true is that *with propeller traction* the task is principally impossible
(at least with a classical propeller) because it is well-known that a propeller
looses its properties when the incident air moves faster than the sound
speed. This is *still* true by the way. There are no supersonic propeller
airplanes.
: > Science considered moving faster than light would be impossible for any matter...
: > Until ... I don't know either, but remember that although our race is gathering knowledge
: > faster than ever before, we don't know yet everything!
Note that the above "limits" were never considered principal limits.
At most one thought of those limits as technological limits. The
lightspeed barrier is of a totally different kind. Of course it is
impossible to foresee where physics will stand 500 years from now,
but currently, breaking the speed barrier, or the 2nd law of thermodynamics,
or conservation of angular momentum are of the same kind: "impossible".
cheers,
Patrick.
--
Patrick Van Esch
mail: van...@dice2.desy.de
for PGP public key: finger van...@dice2.desy.de
Anthony Potts
On Tue, 1 Apr 1997, Guido Wuyts wrote:
> If you visualise the world line of a faster than light particle in a
> Minkowsky diagram you will notice
> that it would coincide with the space axis of some inertial system. This
> implies that in one particular
> inertial system such a particle would actually have to appear as an
> instantaneous, one moment phenomenon.
>
No, it woud appear as a whole series of them. There is not just one "space
axis" you know.
> I myself like to picture mass as a concatenation of light clocks, i.e. a
> web of radiation that goes to and fro within
> a tiny volume that could be associated with this moving mass. Now, this
> description by itself seems to be
> indifferent whether you evolve it along a time-like axis (where it would
> describe subluminal mass) or
> along a space-like (where it would describe a tachyon).
Many people wish to make up such theories. I take it that you
realise just what problems such an approach gives rise to, don't you? For
example, the coupling coefficients for light do not exactly correspond to
that of other matter, and the quantum numbers just don't work.
> As an interested layman about physics I came across many questions
> during my reading, for whose answer I am
> looking for a forum. Would this be the right place or does anyone have a
> better suggestion?
>
Try sci.physics
There are many people there who are interested in helping someone with
questions, as long as you go in with an open mind.
All too often, though, people coming in claiming to be looking for answers
refuse to listen when their errors are pointed out, and start insisting
that everyone else is wrong. So please bear in mind that you are dealing
with people with many many years experience in physics.
Anthony Potts
CERN, Geneva
Anthony Potts
On 2 Apr 1997, Alan Kohler wrote:
> >
> >That is not true.
>
> I think that I'm going to have to toss in with the first poster and say: That
> certainly is true. It was commonly beleieved at the time that if a man
> travelled that fast, he would lose his breath and die.
>
That is quite simply wrong. Men on horseback travelled that fast, people
on trains regularly travelled that fast, and people did not dies in 30
mile per hour winds.
This is one of the most stupid fallacies that I have ever heard. The
counterexamples are just so obvious.
> than relativity, but relativity itself suggests ways of circumventing a
> distance (namely wormholes), in effect allowing FTL travel. (Also, there is
> the theory of tachyons, but that's been discussed here before, so I won't
> expound).
Theory of tachyons?
Tachyons is just the name tat we would give to anything which does indeed
travel faster than light.
As to your comment about wormholes, I am afraid that they don't allow you
to exceed the local speed of light, which is the limit. We know that
globally, over distances where the curvature of space is appreciable, the
speed of light can quite happily be exceeded.
>
> Generally speaking, assuming that we "know everything there is to know" about
> a given subject is scientifically speaking, naive. At the end of the 19th
> century, physics professors encouraged students not to venture further into
> science, as it was beleived that everything that needed known about physics
> was known. However, since then, there have been numerous developments - such
> as relativity and quantum mechanics.
>
Yes, but that in now way suggests that we will be able to accelerate
things past the speed of light.
At CERN, we accelerate electrons to an energy that, if they were not
restricted, woudl equal 300 000 times the speed of light. As it happens,
we do not observe them travelling a single metre per second over the speed
of light.
The light speed barrier is not technical barrier, not an engineering
barrier, but a local speed limit throughout the whole universe.
Yes, the theory might be incorrect, but there is definitely something
going on at light speed, and making better rockets will never take us past
that limit.
Anthony Potts
CERN, Geneva
Shooty
Alan Kohler wrote:
>
> In article <Pine.GSO.3.95a.970401143646.19042T-100000@cms2>, po...@cms.cern.ch
> says...
> >
> >
> >> History shows that:
> >>
> >> Science considered speed of over 30 kph would be deadly for the human
> body...
> >> Until the railroad was invented.
> >>
> >
>
> I think that I'm going to have to toss in with the first poster and say: That
> certainly is true. It was commonly beleieved at the time that if a man
> travelled that fast, he would lose his breath and die.
This wasa not put forward by science or the people who built and
operated the railways. A horse drawn mail coach on a good road would
reach these speeds. The stories were put forward as 'scares' by the
owners of Canal barges, Coaches, draught horses etc. They saw the
railways as a threat to their business. The Stockton and Darlington
railway could move as much coal in one lift from the mines around
Darlington to the Staithes on the river Tees at Stockton as the horse
powered tramway would move in three or four days. A cargo barge would
take a week to trave across the Pennines from Leeds to Manchester, on
the way it had to navigate numerous lock systems that needed a high
level of investment to maintain and keep supplied with water. The
railway cut under the huills and moved the same cargo in a few hours.
and so it goes.
The stories were social not scientific.
Study your history of the Industrial Revolution.
>
Shooty
Richard Caldwell
In Article Re: faster than light travel , Jacob <jal...@hub.ofthe.net> wrote:
> In article <Pine.GSO.3.95a.970401143646.19042T-100000@cms2>, Anthony Potts
> <po...@cms.cern.ch> wrote:
>
> -)On Wed, 19 Jun 1996, Sandro Gisler wrote:
> -)
> -)> History shows that:
> -)>
> -)> Science considered speed of over 30 kph would be deadly for the human
> body...
> -)> Until the railroad was invented.
> -)>
> -)
> -)That is not true.
>
> Incorrect answer! It is true!
No, it is not. There were those who said that traveling faster than 30 mph (note it says MPH, not KPH) in an open vehicle would suck the breath from the passenger, causing suffocation. Others disagreed. "Science" (whatever that is) did not say that it was impossible.
I might note that the same argument arose when railroad locomotives that could exceed 60 MPH were developed. Again, the naysayers were proved wrong.
The point is that, in both cases, uneducated journalists published the warnings of the naysayers in their newspapers because predictions of doom always make good copy that sells papers. And, of course, the uneducated masses bought it.
> -)> Science considered moving faster than acoustic waves would be
> impossible for mankind...
> -)> Until the jet plane was invented.
> -)>
> -)That is not true.
>
> Incorrect answer! It is true!
This one is definitely a myth. Many aircraft designers felt it would be impossible to build a plane (even after the invention of the jet) that was strong enough to withstand the rigors of supersonic flight, with the existing materials.
This *engineering* problem was eventually overcome and supersonic planes were built.
At no time did any "scientist" suggest that it was impossible for something to go faster than sound. Cannon balls had been doing it for centuries. We had already built unmanned rockets that were supersonic (like the German V-2). Everyone knew that supersonic flight was possible and that the problems would eventually be worked out.
But, again, many stories ran in newspapers stating that the "sound barrier" was unbreakable. The scientists just chuckled and shook their heads. There's no way to get the journalists to print the real story. It's too complicated for them to understand and it bores their readers, most of whom can't read/comprehend beyond a grade school level.
> -)> Science considered moving faster than light would be impossible for
> any matter...
> -)> Until ... I don't know either, but remember that although our race is
> gathering knowledge
> -)> faster than ever before, we don't know yet everything!
> -)>
> -)Please, you will have to try harder than that.
Science still considers it impossible to accelerate any object or particle with a non-zero rest mass to the speed of light, much less exceed that speed. Larger and larger particle accelerators have been built that can take a particle to 99.9..% of the
speed of light, but the predictions of the STOR have held true so far.
Tachyons have been hypothesized as being possible. However, no one has ever detected a tachyon, nor has anyone come up with a practical suggestion of how one might go about doing it. Even if we do eventually detect tachyons, eventually, the hypothesis states that their mass is an "imaginary number" (in the mathematical sense). So, we don't have any idea how they would behave.
It may eventually be possible to move an object from point A to point B in a time that is less than that required by a photon to travel the distance. This would creat an apparent or effective FTL motion. But if it is done, it will require some kind of warping of space or other dimensional trick that we can only speculate about today.
Richard
Richard Caldwell
In Article Re: faster than light travel , Alan Kohler <hwk...@REVOVE2REPLYpoky.srv.net> wrote:
> In article <Pine.GSO.3.95a.970401143646.19042T-100000@cms2>, po...@cms.cern.ch
> says...
> >
> >On Wed, 19 Jun 1996, Sandro Gisler wrote:
> >
> >> History shows that:
> >>
> >> Science considered speed of over 30 kph would be deadly for the human
> body...
> >> Until the railroad was invented.
> >>
> >
> >That is not true.
>
> I think that I'm going to have to toss in with the first poster and say: That
> certainly is true. It was commonly beleieved at the time that if a man
> travelled that fast, he would lose his breath and die.
And you are saying that that "common belief" was based on the opinions of the scientists of the day? I doubt that you could be so naive. Common beliefs are rarely scientific. The original poster said "science said", not "it was commonly believed". There is a *big* difference. If you don't see it, you're wasting your time here.
Also the original poster stated that the limit was 30KPH, an obvious error. It was 30MPH, which is considerably faster. I might note that this same rumor arose when man was about to break the 60MPH barrier. There just seemed to be something magical about going "a mile a minute" that the journalists of the day jumped on.
> But I will say that such a notion was certainly less scientifically founded
> than relativity, but relativity itself suggests ways of circumventing a
> distance (namely wormholes), in effect allowing FTL travel. (Also, there is
> the theory of tachyons, but that's been discussed here before, so I won't
> expound).
Yes, there are theories about the possiblity of "getting around" the light barrier. However, none of them suggest that it is possible to simply "push harder" until the light barrier is exceeded. It is well recognized that no type of classical Newtonian (action-reaction) drive can exceed the speed of light.
> Generally speaking, assuming that we "know everything there is to know" about
> a given subject is scientifically speaking, naive. At the end of the 19th
> century, physics professors encouraged students not to venture further into
> science, as it was beleived that everything that needed known about physics
> was known. However, since then, there have been numerous developments - such
> as relativity and quantum mechanics.
True. I believe it was Bertrand Russell who said that man had discovered everything there was to know about physics. Then Einstein published his STOR. All that proves is that scientists are subject to the same weaknesses as any other human being. In this case, I believe it was pompousity, which Russell was well known for. I think this story should serve as a lesson to any future scientist.
Richard
Richard Caldwell
In Article Re: faster than light travel , Patrick van Esch <van...@jamaica.desy.de> wrote:
> Anthony Potts (po...@cms.cern.ch) wrote:
> : On Wed, 19 Jun 1996, Sandro Gisler wrote:
>
> : > History shows that:
> : >
> : > Science considered speed of over 30 kph would be deadly for the human body...
> : > Until the railroad was invented.
> : >
>
> : That is not true.
>
> It is true if you replace "science" by "some peasants" :-)
Well put. It might even be "most peasants", but still well put.
>
> : > Science considered moving faster than acoustic waves would be impossible for mankind...
> : > Until the jet plane was invented.
> : >
> : That is not true.
>
> This is a myth indeed. What *is* true is that many aircraft engineers
> considered the task of making such an airplane challenging. What is also
> true is that *with propeller traction* the task is principally impossible
> (at least with a classical propeller) because it is well-known that a propeller
> looses its properties when the incident air moves faster than the sound
> speed. This is *still* true by the way. There are no supersonic propeller
> airplanes.
Interestingly enough, this is also what keeps the maximum speed of helicopters around 200 MPH. At higher speeds, the speed of the rotor tip on the forward moving side, combined with the overall speed of the helicopter, exceeds the speed of sound, which causes the rotor to do some strange things.
> : > Science considered moving faster than light would be impossible for any matter...
> : > Until ... I don't know either, but remember that although our race is gathering knowledge
> : > faster than ever before, we don't know yet everything!
>
> Note that the above "limits" were never considered principal limits.
> At most one thought of those limits as technological limits. The
> lightspeed barrier is of a totally different kind. Of course it is
> impossible to foresee where physics will stand 500 years from now,
> but currently, breaking the speed barrier, or the 2nd law of thermodynamics,
> or conservation of angular momentum are of the same kind: "impossible".
>
> cheers,
> Patrick.
A very good post.
Richard
Fred McGalliard
Hi. Just thought I would suggest a thought experiment. Without doing the
really messy math, consider two reference frames and an instantenious
travel system. In frame A, this system would work as expected, but in
frame B it would be seen that the transmission actually sends objects
back (or forward) in time an amount t1, a function of the relative
velocity and direction of the translation in the A frame. Considering an
identical system in frame B, we find that traveling back to the starting
point in frame A/B, which hasn't moved much since the experiment doesn't
take much time. Frame A would observe the return leg to involve exactly
the same sort of time translation t1, in the same sense. This suggests
that causality must be violated, and time travel must be possible if FTL
travel is possible. And not only travel, but transmission of data of any
sort. I have not found a clear way to evaluate this but I feel very
uncomfortable with the fact that the time shift is not fixed but a
function of the relative velocity of the observing frame. Perhaps actual
calculations would help here. If I have three frames, would I find that
the time shift predicted conflicts between frames? Would frame C predict
that the return clock is punched in at -t1, +t1 or t2, (correctly
adjusted to match frame translation of course)?
BTW, I get from instantenious to simply FTL by observing that for very
high relativistic frames, the time shift predicted by FTL travel is
greater than the journey time for a fast enough FTL, and causality again
gets the shaft. I think that this argument works down to light speed by
picking faster and faster relative frames. Note that this does not
actually say that we assume FTL communication/travel to be impossible,
but that if it is possible then so is time travel and causality, what we
had to assume to build any theory of physics, is trash.
Fred McGalliard
Patrick van Esch wrote:
...
> This is a myth indeed. What *is* true is that many aircraft engineers
> considered the task of making such an airplane challenging. What is also
> true is that *with propeller traction* the task is principally impossible
> (at least with a classical propeller) because it is well-known that a propeller
> looses its properties when the incident air moves faster than the sound
> speed. This is *still* true by the way. There are no supersonic propeller
> airplanes.
Didn't I hear, about a year or so ago, that a, perhaps very unclassical,
propeller driven plane was proposed to exceed Mach one? I don't think it
was built, but the design concept was discussed.
Patrick Van Esch
Fred McGalliard wrote:
>
> Patrick van Esch wrote:
> > This is *still* true by the way. There are no supersonic propeller
> > airplanes.
>
> Didn't I hear, about a year or so ago, that a, perhaps very unclassical,
> propeller driven plane was proposed to exceed Mach one? I don't think it
> was built, but the design concept was discussed.
I didn't hear of it. If the "propeller" is inside a streamtube
(and is actually a turbine) I could think of a design: first
let the incoming air slow down in a well-designed streamtube
that gets narrower first (to slow down a supersonic incoming
stream - it has the opposite effect as a subsonic stream), have
an expanding tube then to slow down the subsonic stream, put
the propeller there to accelerate the subsonic stream and do
the opposite thing, so that the outgoing jet is supersonic and
faster than the incoming one (hence propulsion). But this is
like a jet plane without a combustion chamber :)
But if the propeller is in the open air, I'd really be surprised !
Well, aerodynamics is a subtle thing, so the rules of thumb aren't
probably always valid.
cheers,
Patrick.
Alan Kohler
In article <Pine.GSO.3.95a.970402111410.27454J-100000@cms2>, po...@cms.cern.ch
says...
>
>On 2 Apr 1997, Alan Kohler wrote:
>
>> >
>>
>> I think that I'm going to have to toss in with the first poster and say:
That
>> certainly is true. It was commonly beleieved at the time that if a man
>> travelled that fast, he would lose his breath and die.
>>
>on trains regularly travelled that fast, and people did not dies in 30
>mile per hour winds.
The number the original poster gave for a speed might have been wrong, but it
WAS indeed believed that to travel too fast would steal ones breath -
admitedly, not too scientifically grounded, but that was widely beleived.
>This is one of the most stupid fallacies that I have ever heard. The
>counterexamples are just so obvious.
Fallacy? No, simple historical fact.
>> than relativity, but relativity itself suggests ways of circumventing a
>> distance (namely wormholes), in effect allowing FTL travel. (Also, there
is
>> the theory of tachyons, but that's been discussed here before, so I won't
>> expound).
>
>Theory of tachyons?
>
>Tachyons is just the name tat we would give to anything which does indeed
>travel faster than light.
>
>As to your comment about wormholes, I am afraid that they don't allow you
>to exceed the local speed of light,
That's why I said "In effect...". Pay attention, please.
> which is the limit. We know that
>globally, over distances where the curvature of space is appreciable, the
>speed of light can quite happily be exceeded.
>
>>
>> Generally speaking, assuming that we "know everything there is to know"
about
>> a given subject is scientifically speaking, naive. At the end of the 19th
>> century, physics professors encouraged students not to venture further into
>> science, as it was beleived that everything that needed known about physics
>> was known. However, since then, there have been numerous developments -
such
>> as relativity and quantum mechanics.
>>
>Yes, but that in now way suggests that we will be able to accelerate
>things past the speed of light.
>
>At CERN, we accelerate electrons to an energy that, if they were not
>restricted, woudl equal 300 000 times the speed of light. As it happens,
>we do not observe them travelling a single metre per second over the speed
>of light.
I never said "relativity is wrong" or "the speed of light is fallacious". I
understand perfectly that simply accelerating a parcticle will never allow it
to exceed the speed of light. I merely suggested that there may be methods
unkown to science now, by which an object can exist at point A at time T=0
sec, and T=1 sec, exist at some point B, which is somewhat more than
2.997x10^10 cm away.
>The light speed barrier is not technical barrier, not an engineering
>barrier, but a local speed limit throughout the whole universe.
>
>Yes, the theory might be incorrect, but there is definitely something
>going on at light speed, and making better rockets will never take us past
>that limit.
I never even suggested the theory was incorrect, nor that making "better
rockets" will give us a real-space velocity greater than light. However,
phenomonon such as wormholes are widely theorized by physicists as existing in
a variety of forms, and it has been suggested that some such wormholes may
even be traversable. By taking a shortcut through another dimention, it may
be possible to circumvent the "speed of light" without ever violating
relativity or making it invalid.
Alan Kohler
In article <Pine.GSO.3.95a.970402110020.27454I-100000@cms2>, po...@cms.cern.ch
says...
>
>On Tue, 1 Apr 1997, Guido Wuyts wrote:
>
>> If you visualise the world line of a faster than light particle in a
>> Minkowsky diagram you will notice
>> that it would coincide with the space axis of some inertial system. This
>> implies that in one particular
>> inertial system such a particle would actually have to appear as an
>> instantaneous, one moment phenomenon.
>>
>No, it woud appear as a whole series of them. There is not just one "space
>axis" you know.
>
>> I myself like to picture mass as a concatenation of light clocks, i.e. a
>> web of radiation that goes to and fro within
>> a tiny volume that could be associated with this moving mass. Now, this
>> description by itself seems to be
>> indifferent whether you evolve it along a time-like axis (where it would
>> describe subluminal mass) or
>> along a space-like (where it would describe a tachyon).
>
>Many people wish to make up such theories. I take it that you
>realise just what problems such an approach gives rise to, don't you? For
>example, the coupling coefficients for light do not exactly correspond to
>that of other matter, and the quantum numbers just don't work.
That's a pretty weak statement, as no "quatum theory" of gravity seems to
work, either, though I'm pretty sure it exists.
Gordon D. Pusch
In article <5hugdl$m...@mars.hyperk.com>
hwk...@REVOVE2REPLYpoky.srv.net (Alan Kohler) writes:
> The number the original poster gave for a speed might have been
> wrong, but it WAS indeed believed that to travel too fast would
> steal ones breath - admitedly, not too scientifically grounded,
> but that was widely beleived.
^^^^^^^^^^^^^^^^^
``Widely believed'' by =whom= ???
As at least one poster has already observed, the is a =VERY= significant
difference between ``uncritically accepted as fact by the general public,''
versus ``accepted as probably valid by the scientific communitee, based
on the best experimental evidence available.''
Your ``fact'' is an example of the former, not the latter: a folk-tale
or superstition believed by the more ignorant and/or uncritical members
of the public, having =NO= basis in fact, =NOT= generally accepted by
the scientific communitee of the time, and indeed, easily falsified
using common, everyday examples of that era, such as galloping horses
or fast steam-engines.
I submit, therefore, that the so-called ``lightspeed barrier'' is
NOT AT ALL similar to the ``30MPH breath-sucking barrier'' ---
it is based on the VERY BEST EXPERIMENTAL EVIDENCE scientists
currently have available, rather than the ignorant superstitions of a
poorly-educated public, exacerbated by muckracking yellow-journalists
eager for a story that would damage the railroad ``Robber-Barons''...
-- Gordon D. Pusch <pu...@mcs.anl.gov>
Disclaimer: I'm a consultant --- I don't speak for ANL or the DOE,
and they *certainly* don't speak for =ME= !!!
Dan Evens
> > Didn't I hear, about a year or so ago, that a, perhaps very unclassical,
> > propeller driven plane was proposed to exceed Mach one? I don't think it
> > was built, but the design concept was discussed.
There is a design for a tubular aircraft. It has no wings and is very
nearly a cylinder. Air is passed through the middle. The device can
supposedly set up some kind of shockwave or something such that it
can travel at supersonic speeds with extremely low drag losses.
(Details a bit fuzzy I admit.)
The ony problem is, the sucker generates no lift. So, the natural
notion is to build it into a blimp design. Result: supersonic
lighter than air vehicle.
--
Standard disclaimers apply.
I don't buy from people who advertise by e-mail.
I don't buy from their ISPs.
Dan Evens
Sylvia Else
Richard Caldwell wrote:
> Even if we do eventually detect tachyons, eventually, the hypothesis
>states that their mass is an "imaginary number" (in the mathematical
>sense).
Actually, I doubt that it validly does even that. If you plug a velocity
greater than that of light into the equations for special relativity, you
do indeed get answers that are imaginary. But it's only reasonable to do
this if the original equations can be derived for such velocities. I
think you'll find that the arguments used for the derivation simply don't
work in those circumstances, so the imaginary mass is meaningless.
Sylvia.
Anthony Potts
On Tue, 1 Apr 1997, Jacob wrote:
> -)
> -)That is not true.
>
> Incorrect answer! It is true!
>
As I hope that you have realised by now, you are incorrect, and are
interpreting what a few uneducated folk thought with what science had
shown.
There is a big difference.
There are many counterexamples to both your points.
It may be helpful if you actually posted some evidence in favour of
positive assertions. Of course, I could not post evidence that it was not
true, as you cannot prove that something wasn't believed.
Press quotations for example, or scientific papers would have shown your
case, had it been true.
Simply stating "it is true" adds nothing to an argument.
If you want to discuss this further, you can email me at a.p...@ic.ac.uk,
and I will take the time to give you some more concrete examples.
I expect, however, that the posts by others should have helped you out
enough.
>
> Incorrect answer! It is true!
>
Putting exclamation marks after your statements does not attest to their
veracity either.
Anthony Potts
Kensington, London
Richard Caldwell
In Article Re: faster than light travel , Alan Kohler <hwk...@REVOVE2REPLYpoky.srv.net> wrote:
> In article <Pine.GSO.3.95a.970402111410.27454J-100000@cms2>, po...@cms.cern.ch
> says...
> >
> >On 2 Apr 1997, Alan Kohler wrote:
> >
> >> >
> >> >That is not true.
> >>
> >> I think that I'm going to have to toss in with the first poster and say:
> That
> >> certainly is true. It was commonly beleieved at the time that if a man
> >> travelled that fast, he would lose his breath and die.
> >>
> >That is quite simply wrong. Men on horseback travelled that fast, people
> >on trains regularly travelled that fast, and people did not dies in 30
> >mile per hour winds.
>
> The number the original poster gave for a speed might have been wrong, but it
> WAS indeed believed that to travel too fast would steal ones breath -
> admitedly, not too scientifically grounded, but that was widely beleived.
"Widely believed", perhaps. But the original poster said that it was believed by the scientists of the day. This is not true. The beliefs were proposed by non-scientists (for their own reasons), propagated by journalists (to sell papers), and believed by the uneducated public. This is very different from "science said".
> >This is one of the most stupid fallacies that I have ever heard. The
> >counterexamples are just so obvious.
>
> Fallacy? No, simple historical fact.
History has a way of getting re-written on this newsgroup. 8-]
Agreed.
> >The light speed barrier is not technical barrier, not an engineering
> >barrier, but a local speed limit throughout the whole universe.
> >
> >Yes, the theory might be incorrect, but there is definitely something
> >going on at light speed, and making better rockets will never take us past
> >that limit.
>
> I never even suggested the theory was incorrect, nor that making "better
> rockets" will give us a real-space velocity greater than light. However,
> phenomonon such as wormholes are widely theorized by physicists as existing in
> a variety of forms, and it has been suggested that some such wormholes may
> even be traversable. By taking a shortcut through another dimention, it may
> be possible to circumvent the "speed of light" without ever violating
> relativity or making it invalid.
Agreed, and I sure hope you are right. Otherwise, we're stuck in a pretty small neighborhood. 8-[
Richard
Richard Caldwell
In Article Re: faster than light travel , Patrick Van Esch <Patrick...@ping.be> wrote:
> Fred McGalliard wrote:
> >
> > Patrick van Esch wrote:
> > > This is *still* true by the way. There are no supersonic propeller
> > > airplanes.
> >
> > Didn't I hear, about a year or so ago, that a, perhaps very unclassical,
> > propeller driven plane was proposed to exceed Mach one? I don't think it
> > was built, but the design concept was discussed.
>
> I didn't hear of it. If the "propeller" is inside a streamtube
> (and is actually a turbine) I could think of a design: first
> let the incoming air slow down in a well-designed streamtube
> that gets narrower first (to slow down a supersonic incoming
> stream - it has the opposite effect as a subsonic stream), have
> an expanding tube then to slow down the subsonic stream, put
> the propeller there to accelerate the subsonic stream and do
> the opposite thing, so that the outgoing jet is supersonic and
> faster than the incoming one (hence propulsion). But this is
> like a jet plane without a combustion chamber :)
> But if the propeller is in the open air, I'd really be surprised !
> Well, aerodynamics is a subtle thing, so the rules of thumb aren't
> probably always valid.
There have also been proposals for propellers to go on turbo-prop type airliners that are shaped so that the propeller tips can exceed the speed of sound without causing any problems. These propellers fit on the back end of the engine, instead of the front, so that any turbulance generated trails off behind the engine/aircraft. Some of these designs have actually been tested. However, I don't recall hearing any proposals for such designs where the aircraft itself would be super-sonic.
Richard
Richard Caldwell
That's my point, exactly. In mathematics, "imaginary" implies undefined. So, "imaginary mass" would be undefined, which implies that it is meaningless. Therefor,
tachyons, which some people accept as a proven fact (probably from watching Star Trek), are, in fact, a purely hypothetical particle with meaningless mass. They are like the faeries that dance on the head of a pin.
Of course, one must remember that neutrinos also were hypothetical. But, the difference is that their existence was *required* by the laws of conservation of energy and momentum for nuclear reactions. Therefore, it was a matter of finding a particle that *must* exist, not one that some theoretician suggested *might* exist. The distinction may be lost on some, but it's a biggie.
Richard
William L. Bahn
Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote in
article
<Forum.859999517.197...@OSF25.oklaosf.state.ok.us>...
>
> In Article Re: faster than light travel , Patrick van Esch
<van...@jamaica.desy.de> wrote:
>
<snip>
> : > Science considered moving faster than acoustic waves would be
impossible for mankind...
> > : > Until the jet plane was invented.
> > : >
> > : That is not true.
> >
> > This is a myth indeed. What *is* true is that many aircraft engineers
> > considered the task of making such an airplane challenging. What is
also
> > true is that *with propeller traction* the task is principally
impossible
> > (at least with a classical propeller) because it is well-known that a
propeller
> > looses its properties when the incident air moves faster than the sound
> > speed. This is *still* true by the way. There are no supersonic
propeller
> > airplanes.
>
> Interestingly enough, this is also what keeps the maximum speed of
> helicopters around 200 MPH. At higher speeds, the speed of the rotor tip
> on the forward moving side, combined with the overall speed of the
helicopter,
> exceeds the speed of sound, which causes the rotor to do some strange
things.
>
There is another effect, which I believe is the dominant factor. The speed
of the rotor on the other side (the retreating blade) is diminished by the
forward speed of the helicopter. At some point, the retreating blade is no
longer able to generate sufficient lift and stalls, (known, not
surprisingly, as retreating blade stall). The helicopter then enters a
rather violent roll but, I understand, this is a recoverable event provided
max. stresses are not exceeded (I can't attest to this, since I am not a
helicopter pilot).
Wayne Throop
: Fred McGalliard <frederick.b...@boeing.com>
: consider two reference frames and an instantenious travel system. In
: frame A, this system would work as expected, but in frame B it would
: be seen that the transmission actually sends objects back (or forward)
: in time an amount t1, a function of the relative velocity and
: direction of the translation in the A frame.
And the distance moved. The term from the lorentz transforms
that implies this is -vx/sqrt(1-v^2/c^2).
: Considering an identical system in frame B, we find that traveling
: back to the starting point in frame A/B, which hasn't moved much since
: the experiment doesn't take much time. Frame A would observe the
: return leg to involve exactly the same sort of time translation t1, in
: the same sense. This suggests that causality must be violated, and
: time travel must be possible if FTL travel is possible.
Right.
: I have not found a clear way to evaluate this but I feel very
: uncomfortable with the fact that the time shift is not fixed but a
: function of the relative velocity of the observing frame.
And the distance. Don't forget the distance. But the key point isn't
that the time shift is a function of the "observing" frame. The time
shift in terms of physical clock ticks on physical clocks is a function
of the relative velocity of the sending frame and the receiving frame.
It really does have to do with the real live physics of the situation,
not just related to who's watching.
: Perhaps actual calculations would help here. If I have three frames,
: would I find that the time shift predicted conflicts between frames?
: Would frame C predict that the return clock is punched in at -t1, +t1
: or t2, (correctly adjusted to match frame translation of course)?
Well, an actual case is pursued on
http://sheol.org/throopw/tachyon-pistols.html
with both numbers and a spacetime diagram, and further diagrams
that may help make what's going on clear are at
http://sheol.org/throopw/jumpship-timetravel.gif
http://sheol.org/throopw/noninstant-ftl-timetravel.gif
If you want to understand how to read the spacetime diagrams I draw,
and the significance of the "lines of simultaneity", then
http://sheol.org/throopw/sr-ticks-n-bricks.html
may be of use. See also the Hinson FTL pages:
http://www.physics.purdue.edu/~hinson/ftl/FTL_intro_html.html
And of course for general background, the relativity FAQ
http://www.public.iastate.edu/~physics/sci.physics/faq/relativity.html
Or for more general background, try textbooks: Epstein's
"Relativity Visualized", or Taylor and Wheeler's "Spacetime Physics"
are good starting places. (Note that Epstein's diagrams are different
from the more usual kind of spacetime diagrams most folks use...)
--
Wayne Throop thr...@sheol.org http://sheol.org/throopw
thr...@cisco.com
Alan DeKok
In article <Forum.860095382.30...@OSF25.oklaosf.state.ok.us>,
Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote:
>
>In Article Re: faster than light travel , Sylvia Else <syl...@xip.com.au> wrote:
>
>> Actually, I doubt that it validly does even that. If you plug a velocity
>> greater than that of light into the equations for special relativity, you
>> do indeed get answers that are imaginary. But it's only reasonable to do
>> this if the original equations can be derived for such velocities. I
>> think you'll find that the arguments used for the derivation simply don't
>> work in those circumstances, so the imaginary mass is meaningless.
>
No, 'imaginary' means the square root of -1, or 'i'. It has a
well-accepted definition.
Don't confuse the inadequate colloquial English term 'imaginary' with
the mathematical definition of 'i'.
> So, "imaginary mass" would be undefined, which implies that it is
> meaningless. Therefor, tachyons, which some people accept as a proven
> fact (probably from watching Star Trek), are, in fact, a purely
> hypothetical particle with meaningless mass. They are like the faeries
> that dance on the head of a pin.
Tachyons have not been observed, so their existence is purely
hypothetical. Your argument is incorrect.
> Of course, one must remember that neutrinos also were hypothetical.
> But, the difference is that their existence was *required* by the laws of
> conservation of energy and momentum for nuclear reactions. Therefore, it
> was a matter of finding a particle that *must* exist, not one that
> some theoretician suggested *might* exist.
That's correct, at least. Physicists had the choice to either throw
out umpteen conservation laws, or postulate a particle which was _really_
difficult to detect. Once they were observed in an experiment, everyone
pretty much accepted that neutrinos existed, and the conservation laws
were correct.
Alan DeKok.
me...@cars3.uchicago.edu
In article <Forum.860095382.30...@OSF25.oklaosf.state.ok.us>, Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> writes:
>
>In Article Re: faster than light travel , Sylvia Else <syl...@xip.com.au> wrote:
>
>> Actually, I doubt that it validly does even that. If you plug a velocity
>> greater than that of light into the equations for special relativity, you
>> do indeed get answers that are imaginary. But it's only reasonable to do
>> this if the original equations can be derived for such velocities. I
>> think you'll find that the arguments used for the derivation simply don't
>> work in those circumstances, so the imaginary mass is meaningless.
>>
>
>That's my point, exactly. In mathematics, "imaginary" implies undefined.
Only in your imagination :-)
Mati Meron | "When you argue with a fool,
me...@cars.uchicago.edu | chances are he is doing just the same"
Richard Logan
Richard Caldwell wrote:
>
> That's my point, exactly. In mathematics, "imaginary" implies > undefined.
False. Imaginary numbers are in no way undefined. The definition if i
is just the square root of -1. Imaginary numbers are used to describe
phase shifts (for instance, the phase shift in current and voltage
across a capacitor) among other useful things.
me...@cars3.uchicago.edu
In article <Forum.860105292.26...@OSF25.oklaosf.state.ok.us>, Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> writes:
>
>In Article Re: faster than light travel , me...@cars3.uchicago.edu wrote:
>
>> In article <Forum.860095382.30...@OSF25.oklaosf.state.ok.us>, Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> writes:
>
>> >In Article Re: faster than light travel , Sylvia Else <syl...@xip.com.au> wrote:
>> >
>> >> Actually, I doubt that it validly does even that. If you plug a velocity
>> >> greater than that of light into the equations for special relativity, you
>> >> do indeed get answers that are imaginary. But it's only reasonable to do
>> >> this if the original equations can be derived for such velocities. I
>> >> think you'll find that the arguments used for the derivation simply don't
>> >> work in those circumstances, so the imaginary mass is meaningless.
>> >>
>> >> Sylvia.
>> >
>>
>
>terms, what it means for a particla to have an "imaginary mass".
I was commenting on your math, not physics. In mathematics "imaginary"
is very well defined.
>I know the mathematical definition of "imaginary" (* -1^0.5)
OK
> but that's an abstract mathematical concept. I don't know what it
> means in physical terms, so I call that "undefined".
Than you didn't express yourself very well. You should've said
"imaginary mass is undefined" not "in mathematics imaginary mass
implies undefined". It is like the difference between saying "red
swans don't exist" and "the color ""red"" doesn't exist".
Richard Caldwell
In Article Re: faster than light travel , me...@cars3.uchicago.edu wrote:
> In article <Forum.860095382.30...@OSF25.oklaosf.state.ok.us>, Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> writes:
> >In Article Re: faster than light travel , Sylvia Else <syl...@xip.com.au> wrote:
> >
> >> Actually, I doubt that it validly does even that. If you plug a velocity
> >> greater than that of light into the equations for special relativity, you
> >> do indeed get answers that are imaginary. But it's only reasonable to do
> >> this if the original equations can be derived for such velocities. I
> >> think you'll find that the arguments used for the derivation simply don't
> >> work in those circumstances, so the imaginary mass is meaningless.
> >>
> >> Sylvia.
> >
> >That's my point, exactly. In mathematics, "imaginary" implies undefined.
>
> Only in your imagination :-)
Well then, fire up your superior imagination and explain to me, in physical terms, what it means for a particla to have an "imaginary mass".
I know the mathematical definition of "imaginary" (* -1^0.5) but that's an abstract mathematical concept. I don't know what it means in physical terms, so I call that "undefined". If you do know what it means in physical terms, pleas explain it to me. 8-]
Richard
Alan Kohler
In article <ph3et95...@xanadu.mcs.anl.gov>, pu...@mcs.anl.gov says...
>> wrong, but it WAS indeed believed that to travel too fast would
>> steal ones breath - admitedly, not too scientifically grounded,
>> but that was widely beleived.
>
>``Widely believed'' by =whom= ???
>
>As at least one poster has already observed, the is a =VERY= significant
>difference between ``uncritically accepted as fact by the general public,''
>versus ``accepted as probably valid by the scientific communitee, based
>on the best experimental evidence available.''
I don't have the reference that I pulled that from handy to tell you exactly
what "widely believed" meant (I'm an engineer, not a historian - it was just
an interesting quip that I read once, and didn't pay much regard to
remembering where I read it - I was just throwing in with the original poster
because everyone else was categorically denying that this beleif existed,
which just isn't the case.), but if I remember correctly, it extended to the
scientific community as well.
But even if I did dig it up, I think your missing the point. You appear to
think that I'm using that as an argument to suggest that relativity is false -
which is not the case, as you would see if you paid a little more attention
and read a little deeper into the thread before you hit the "reply to" button.
The point is that even scientists have misconceptions simply because they are
relying on incomplete
models and incomplete knowledge. There's nothing in newtonian mechanics which
says that if enough force is applied to an object, it won't go faster than
light; it turns out, however, newtonian mechanics are a very specific sub-set
of einteinian relativity which tells us that simply accelerating an object
will not make it go faster than light. In a similar vein (but different
field), doctors once did not beleive that not washing thier hands before
examining an expectant mother would affect the health of the expectant mother.
>Your ``fact'' is an example of the former, not the latter: a folk-tale
>or superstition believed by the more ignorant and/or uncritical members
>of the public, having =NO= basis in fact, =NOT= generally accepted by
>the scientific communitee of the time,
Do you know it was *NOT* accepted by the scientific community at the time? I
beleive it probably was (as I said, I have not been able to re-locate the
reference for that - but nor have you presented evidence to the contrary.)
And my "fact" was a historical statement about BELIEFS; I was never asserting
that the "wind sucking" limit was a fact.
>I submit, therefore, that the so-called ``lightspeed barrier'' is
>NOT AT ALL similar to the ``30MPH breath-sucking barrier'' ---
>it is based on the VERY BEST EXPERIMENTAL EVIDENCE scientists
>currently have available, rather than the ignorant superstitions of a
>poorly-educated public, exacerbated by muckracking yellow-journalists
>eager for a story that would damage the railroad ``Robber-Barons''...
I never said it was similar (though the original poster probably meant to
imply such...) The whole point is that to assume we know everything
concerning physics - or any other subject - would be folly. Note your own
wording:
VERY BEST EXPERIMENTAL EVIDENCE scientists *currently have available*
(starred emphasis mine)
Let me emphasize a point that you and some other equally unatentive posters
seemed to have missed: I'm not suggesting that a VELOCITY greater than light
is possible. What I am suggesting is that it MAY BE possible for an object to
"traverse" a distance between 2 points in a shorter time than light would.
There are some highly qualified theoretical physicists who have some
facinating theories on wormholes and their paractical contruction (esp.
Michael Morris, Kip Thorne, and Matt Visser). Just because we cannot
explicity prove these theories today does not mean they are not possible.
Alan Kohler
In article <Forum.860095382.30...@OSF25.oklaosf.state.ok.us>,
richard....@OSF25.oklaosf.state.ok.us says...
>>
>> > Even if we do eventually detect tachyons, eventually, the hypothesis
>> >states that their mass is an "imaginary number" (in the mathematical
>> >sense).
>>
>> greater than that of light into the equations for special relativity, you
>> do indeed get answers that are imaginary. But it's only reasonable to do
>> this if the original equations can be derived for such velocities. I
>> think you'll find that the arguments used for the derivation simply don't
>> work in those circumstances, so the imaginary mass is meaningless.
>>
>> Sylvia.
>
>That's my point, exactly. In mathematics, "imaginary" implies undefined.
"Implies" ... good choice of words. As anyone who works with electricity will
tell you, some quantities defined by imaginary numbers have very real effects
on the real world. However, if a tachyon interacts with the known universe
anything like known particles do, we would expect to see flashed of cherenkov
radiation in empty space - and we don't. That's the most compelling evidence
agaisnt tachyons.
>Of course, one must remember that neutrinos also were hypothetical. But, the
difference is that their existence was *required* by the laws of conservatio
the excessively long line was hacked off by my reader - I beleive he menat to
finish "conservation of momentum."
True, but there are many particles postulated by prominent theories that
haven't made a showing yet - sparticles and massive monopoles being two
examples. Perhaps tachyons do exist, they just don't interact strongly (or at
all) with the universe as we know it. Or perhaps they are just a mathematical
pipe-dream.
William Barwell
In article <Forum.860095382.30...@OSF25.oklaosf.state.ok.us>,
Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote:
>
>In Article Re: faster than light travel , Sylvia Else <syl...@xip.com.au> wrote:
>
>> Richard Caldwell wrote:
>>
>> > Even if we do eventually detect tachyons, eventually, the hypothesis
>> >states that their mass is an "imaginary number" (in the mathematical
>> >sense).
>>
>> Actually, I doubt that it validly does even that. If you plug a velocity
>> greater than that of light into the equations for special relativity, you
>> do indeed get answers that are imaginary. But it's only reasonable to do
>> this if the original equations can be derived for such velocities. I
>> think you'll find that the arguments used for the derivation simply don't
>> work in those circumstances, so the imaginary mass is meaningless.
>>
>> Sylvia.
>
>That's my point, exactly. In mathematics, "imaginary" implies undefined.
So, "imaginary mass" would be undefined, which implies that it is
>tachyons, which some people accept as a proven fact (probably from
watching Star Trek), are, in fact, a purely hypothetical particle with
meaningless mass. They are like the faeries that dance on the head of a pin.
Tachyons had specific and testable consequences. Several
careful tests disposed of the idea that they exist.
Even if they existed, they would not help us move faster
than light. As we are made of baryons, not tachyons.
Baryons cannot possible move faster than C, hypothetical tachyons were
supposedly unable to move slower than C.
Pope Charles
SubGenius Pope Of Houston
Slack!
Andrew Pliml
This is obviously crap. If you want FTL travel, see some REAL,
SCIENTIFIC discussion on the subject, not this religious garbage.
Andrew Pliml
Alan DeKok
[ extraneous newsgroups snipped ]
In article <Forum.860105292.26...@OSF25.oklaosf.state.ok.us>,
Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote:
>
> I know the mathematical definition of "imaginary" (* -1^0.5) but that's
> an abstract mathematical concept.
Like 1, or 2, or even 5.
> I don't know what it means in physical terms, so I call that "undefined".
Perhaps you should try to use something other than your own personal
naming convention.
> If you do know what it means in
> physical terms, pleas explain it to me.
What does '1' mean in physical terms? You can't explain it.
Sure, you can point to a rock, but it's just a rock. It doesn't
physically signify '1'.
Alan DeKok.
thomas.kalbfus
William Barwell <wbar...@Starbase.NeoSoft.COM> wrote in article <
> Tachyons had specific and testable consequences. Several
> careful tests disposed of the idea that they exist.
>
> Even if they existed, they would not help us move faster
> than light. As we are made of baryons, not tachyons.
> Baryons cannot possible move faster than C, hypothetical tachyons were
> supposedly unable to move slower than C.
But if tachyons and Baryons can interact with each other, then real time
communication with points in space that are light years away becomes
possible. Using telerobotics, a person can experience the conditions on a
planet that is light years away without leaving Earth. The only technology
thats missing is a faster than light communication system. If we substitute
tachyons for radio waves, faster than light travel becomes unnecessary. The
lowest energy tachyons are the ones that trave the fastest which means near
instantaneous speeds, its only when you try to slow them down does reverse
time dialation come into effect.
Anthony Potts
On Wed, 2 Apr 1997, Richard Caldwell wrote:
>
> Interestingly enough, this is also what keeps the maximum speed of helicopters around 200 MPH. At higher speeds, the speed of the rotor tip on the forward moving side, combined with the overall speed of the helicopter, exceeds the speed of sound, which causes the rotor to do some strange things.
Actually, I believe that a Lynx has exceeded 400mph.
Not that I used to work for the military or anything...
Anthony Potts
Kensington, London
me...@cars3.uchicago.edu
In article <Pine.GSO.3.95a.970404101643.3927A-100000@cms2>, Anthony Potts <po...@cms.cern.ch> writes:
>On Wed, 2 Apr 1997, Richard Caldwell wrote:
>
>>
>> Interestingly enough, this is also what keeps the maximum speed of helicopters around 200 MPH. At higher speeds, the speed of the rotor tip on the forward moving side, combined with the overall speed of the helicopter, exceeds the speed of sound, whic
>
>
>Not that I used to work for the military or anything...
>
Anthony Potts
On Thu, 3 Apr 1997, Richard Caldwell wrote:
>
> I know the mathematical definition of "imaginary" (* -1^0.5) but that's an abstract mathematical concept. I don't know what it means in physical terms, so I call that "undefined". If you do know what it means in physical terms, pleas explain it to me. 8-]
>
It generally refers to a phase change.
Anthony Potts
Kensington, London
Simon Cast
Richard Caldwell wrote:
>
> Well then, fire up your superior imagination and explain to me, in physical terms, what it means for a particla to have an "imaginary mass".
>
>
Think of speed of light as a barrier. On this side imaginary numbers are
imaginary and so particles based on them are considered undefined,
however travel on the other side of the barrier than then the imaginary
number's become real and the real numbers become imaginary and so the
imaginary particles become real.
At least that's one way to look at it. Since for all we know the math on
the other side could easily be the reverse of what it is on this side.
SImon
Simon Cast
William Barwell wrote:
>
> Tachyons had specific and testable consequences. Several
> careful tests disposed of the idea that they exist.
>
> Even if they existed, they would not help us move faster
> than light. As we are made of baryons, not tachyons.
> Baryons cannot possible move faster than C, hypothetical tachyons were
> supposedly unable to move slower than C.
>
> SubGenius Pope Of Houston
> Slack!
Possible you could create a field(barrier) of tachyons around the
baryons so while the baryons don't travel faster than light within the
field the overall field including the baryons could.
A possibility, slim, but still a possibility.
Simon
The Spy
Richard Caldwell wrote:
>>>The light speed barrier is not technical barrier, not an engineering
>>>barrier, but a local speed limit throughout the whole universe.
>>>
>>>Yes, the theory might be incorrect, but there is definitely something
>>>going on at light speed, and making better rockets will never take us past
>>>that limit.
I read that as you approach the speed of light, matter and energy become
interchangeable. Any attempt at reaching the speed of light would cause a
breakdown of the entire ship.
Richard Caldwell
In Article Re: faster than light travel , Alan DeKok <aland@z[achilles.net]> wrote:
> In article <Forum.860095382.30...@OSF25.oklaosf.state.ok.us>,
> Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote:
> >
> >In Article Re: faster than light travel , Sylvia Else <syl...@xip.com.au> wrote:
> >
> >> Actually, I doubt that it validly does even that. If you plug a velocity
> >> greater than that of light into the equations for special relativity, you
> >> do indeed get answers that are imaginary. But it's only reasonable to do
> >> this if the original equations can be derived for such velocities. I
> >> think you'll find that the arguments used for the derivation simply don't
> >> work in those circumstances, so the imaginary mass is meaningless.
> >
> >That's my point, exactly. In mathematics, "imaginary" implies undefined.
>
> No, 'imaginary' means the square root of -1, or 'i'. It has a
> well-accepted definition.
>
> Don't confuse the inadequate colloquial English term 'imaginary' with
> the mathematical definition of 'i'.
I'm not confusing anything. I am well aware of the mathematical definition of "imaginary". However, this is an abstract, mathematical definition. It tells us *nothing* about the real physical characteristics of a particle that has an "imaginary mass". Therefore, in the physical sense, such a mass is undefined.
> > So, "imaginary mass" would be undefined, which implies that it is
> > meaningless. Therefor, tachyons, which some people accept as a proven
> > fact (probably from watching Star Trek), are, in fact, a purely
> > hypothetical particle with meaningless mass. They are like the faeries
> > that dance on the head of a pin.
>
> Tachyons have not been observed, so their existence is purely
> hypothetical. Your argument is incorrect.
Apparently, you didn't even read my argument. I draw your attention to the phrase "tachyons, .... , are, in fact, a purely hypothetical particle" in the paragraph above. I realize that I tend to write long sentences, with lots of commas. Maybe you just missed it.
> > Of course, one must remember that neutrinos also were hypothetical.
> > But, the difference is that their existence was *required* by the laws of
> > conservation of energy and momentum for nuclear reactions. Therefore, it
> > was a matter of finding a particle that *must* exist, not one that
> > some theoretician suggested *might* exist.
>
> That's correct, at least.
Gee, thanks, professor. I guess I finally wrote something clearly enough for you to understand it. Or, you actually bothered to read what I wrote, one or the other. 8-]
> Physicists had the choice to either throw
> out umpteen conservation laws, or postulate a particle which was _really_
> difficult to detect. Once they were observed in an experiment, everyone
> pretty much accepted that neutrinos existed, and the conservation laws
> were correct.
>
> Alan DeKok.
Agreed.
Richard
Richard Caldwell
In Article Re: faster than light travel , me...@cars3.uchicago.edu wrote:
> In article <Forum.860105292.26...@OSF25.oklaosf.state.ok.us>, Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> writes:
> >
> >In Article Re: faster than light travel , me...@cars3.uchicago.edu wrote:
> >
> >> In article <Forum.860095382.30...@OSF25.oklaosf.state.ok.us>, Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> writes:
> >
> >> >In Article Re: faster than light travel , Sylvia Else <syl...@xip.com.au> wrote:
> >> >
> >> >> Actually, I doubt that it validly does even that. If you plug a velocity
> >> >> greater than that of light into the equations for special relativity, you
> >> >> do indeed get answers that are imaginary. But it's only reasonable to do
> >> >> this if the original equations can be derived for such velocities. I
> >> >> think you'll find that the arguments used for the derivation simply don't
> >> >> work in those circumstances, so the imaginary mass is meaningless.
> >> >>
> >> >> Sylvia.
> >> >
> >> >That's my point, exactly. In mathematics, "imaginary" implies undefined.
> >>
> >> Only in your imagination :-)
> >
> >Well then, fire up your superior imagination and explain to me, in physical
> >terms, what it means for a particla to have an "imaginary mass".
>
> I was commenting on your math, not physics. In mathematics "imaginary"
> is very well defined.
Fine. Since I am not a mathematician, you take "my math" and sell it to the highest bidder. My point was one about physical reality. Unfortunately, your precious mathematics doesn't supply us with any definition of what it means for a particle to have an "imaginary mass". Therefore, in physical terms, imaginary -> undefined.
> >I know the mathematical definition of "imaginary" (* -1^0.5)
>
> OK
>
> > but that's an abstract mathematical concept. I don't know what it
> > means in physical terms, so I call that "undefined".
>
> Than you didn't express yourself very well. You should've said
> "imaginary mass is undefined" not "in mathematics imaginary mass
> implies undefined". It is like the difference between saying "red
> swans don't exist" and "the color ""red"" doesn't exist".
At least I know the difference between "than" and "then". I suspect that you zeroed in on the phrase about mathematics above, lifted it out of context, and found something to pounce on me about. If nit-picking people on points about mathematics is your sport, have fun. I never much liked the mathematicians in my physics classes anyway. They got all the A's, while us physics majors had to settle for B's. 8-]
Richard
Richard Caldwell
In Article Re: faster than light travel , Richard Logan <rlo...@space.honeywell.com>
> Richard Caldwell wrote:
> >
> > That's my point, exactly. In mathematics, "imaginary" implies > undefined.
>
> False. Imaginary numbers are in no way undefined. The definition if i
> is just the square root of -1. Imaginary numbers are used to describe
> phase shifts (for instance, the phase shift in current and voltage
> across a capacitor) among other useful things.
Great! Now, would you please explain to me what it means, in real physical terms, for a particle to have a mass given by the expression m*-1^0.5? Until you can, my point stands. Of course, taken out of context, my statement above is false. But, in the context of the "imaginary mass" of the tachyon, which I was discussing, it's not the same.
Richard
Richard Caldwell
In Article Re: faster than light travel , Anthony Potts <po...@cms.cern.ch> wrote:
> On Wed, 2 Apr 1997, Richard Caldwell wrote:
>
> >
> > Interestingly enough, this is also what keeps the maximum speed of helicopters around 200 MPH. At higher speeds, the speed of the rotor tip on the forward moving side, combined with the overall speed of the helicopter, exceeds the speed of sound, which causes the rotor to do some strange things.
>
> Actually, I believe that a Lynx has exceeded 400mph.
Another mixing of units, here. The Lynx exceeded 400 *KPH*, which is around 250 MPH.
> Not that I used to work for the military or anything...
Nor I, but I do read rec.aviation.military. 8-]
> Anthony Potts
>
> Kensington, London
Richard
Richard Caldwell
In Article Re: faster than light travel , Simon Cast <s34...@student.uq.edu.au> wrote:
> Richard Caldwell wrote:
> >
> > Well then, fire up your superior imagination and explain to me, in physical terms, what it means for a particla to have an "imaginary mass".
> >
> > I know the mathematical definition of "imaginary" (* -1^0.5) but that's an abstract mathematical concept. I don't know what it means in physical terms, so I call that "undefined". If you do know what it means in physical terms, pleas explain it to me. 8-]
> >
> > Richard
>
> Think of speed of light as a barrier. On this side imaginary numbers are
> imaginary and so particles based on them are considered undefined,
> however travel on the other side of the barrier than then the imaginary
> number's become real and the real numbers become imaginary and so the
> imaginary particles become real.
>
> At least that's one way to look at it. Since for all we know the math on
> the other side could easily be the reverse of what it is on this side.
>
> SImon
Since nobody knows what "the other side" might be like, your guess (and that's all it is) is as good as anybody's. 8-]
Richard
Richard Caldwell
In Article Re: faster than light travel , "thomas.kalbfus" <thomas....@MCIONE.com> wrote:
> William Barwell <wbar...@Starbase.NeoSoft.COM> wrote in article <
> > Tachyons had specific and testable consequences. Several
> > careful tests disposed of the idea that they exist.
> >
> > Even if they existed, they would not help us move faster
> > than light. As we are made of baryons, not tachyons.
> > Baryons cannot possible move faster than C, hypothetical tachyons were
> > supposedly unable to move slower than C.
>
> But if tachyons and Baryons can interact with each other, then real time
> communication with points in space that are light years away becomes
> possible. Using telerobotics, a person can experience the conditions on a
> planet that is light years away without leaving Earth. The only technology
> thats missing is a faster than light communication system. If we substitute
> tachyons for radio waves, faster than light travel becomes unnecessary. The
> lowest energy tachyons are the ones that trave the fastest which means near
> instantaneous speeds, its only when you try to slow them down does reverse
> time dialation come into effect.
That's all based on the assumptions that tachyons even exist. To date, all experiments to detect tachyons, or their effects, have had negative results.
Richard
Richard Caldwell
In Article Re: faster than light travel , Anthony Potts <po...@cms.cern.ch> wrote:
> On Thu, 3 Apr 1997, Richard Caldwell wrote:
>
> >
> > I know the mathematical definition of "imaginary" (* -1^0.5) but that's an abstract mathematical concept. I don't know what it means in physical terms, so I call that "undefined". If you do know what it means in physical terms, pleas explain it to me. 8-]
> >
> It generally refers to a phase change.
So, what does "phase change" mean when talking about the mass of a particle?
Richard
Richard Caldwell
What you read is probably some Sci-Fi clap-trap. Matter and energy are interchangeable at any speed. This relationship is described by the famous equation, E=mc^2. Of course, getting them to "interchange" is another trick.
What you *should* have read (in a physics text) was, as you approach the speed of light, your mass approaches infinity. Not good news for those of us who would like to lose some weight. 8-]
Richard
Richard Caldwell
In Article Re: faster than light travel , Edward Edmondson <Edw...@yendor.demon.co.uk> wrote:
> Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote
> >That's my point, exactly. In mathematics, "imaginary" implies undefined. So,
> >"imaginary mass" would be undefined, which implies that it is meaningless.
> Imaginary implies undefined? I thought imaginary, and complex
> mathematics was completely well defined. Admittedly it may not have much
> relevance in nature - almost always complex numbers get multiplied by
> their conjugates before giving an answer to any physical problem so that
> imaginary numbers don't tend to have a hard physical meaning in the same
> way that real numbers do.
> Multiplication by a conjugate makes the imaginary component of a complex
> number into a real bit, and so a complex number is transformed to a real
> one, after all the clever maths needing complex numbers is done.
> [I think.]
My, my! This thread is full of mathematicians who read that one sentence, evidently out of context, and jumped all over it.
OK, I STAND CORRECTED. THE TERM "IMAGINARY" IS VERY WELL DEFINED IN MATHEMATICS.
Of course, that defintion tells us nothing about the physical reality of a particle that has "imaginary mass", so the original meaning of what I said still stands. I will rephrase it:
If a particle has an "imaginary mass", as defined in mathematics, this implies that the mass of the particle is "undefined" in any real, physical sense.
Does that satisfy you nit-picking mathematicians? 8-]
I always hated the mathematicians in my physics classes. They got all the A's, while we physics majors got B's, and they wouldn't go to the local pub for a few pithchers of beer. 8-]
Richard
Steve Giblin
In article <Forum.860170392.12...@OSF25.oklaosf.state.ok.us>,
Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote:
#
#In Article Re: faster than light travel , "thomas.kalbfus"
<thomas....@MCIONE.com> wrote:
#
#> William Barwell <wbar...@Starbase.NeoSoft.COM> wrote in article <
#> > Tachyons had specific and testable consequences. Several
#> > careful tests disposed of the idea that they exist.
#> >
#> > Even if they existed, they would not help us move faster
#> > than light. As we are made of baryons, not tachyons.
#> > Baryons cannot possible move faster than C, hypothetical tachyons were
#> > supposedly unable to move slower than C.
#>
#> But if tachyons and Baryons can interact with each other, then real time
#> communication with points in space that are light years away becomes
#> possible. Using telerobotics, a person can experience the conditions on a
#> planet that is light years away without leaving Earth. The only technology
#> thats missing is a faster than light communication system. If we substitute
#> tachyons for radio waves, faster than light travel becomes unnecessary. The
#> lowest energy tachyons are the ones that trave the fastest which means near
#> instantaneous speeds, its only when you try to slow them down does reverse
#> time dialation come into effect.
#
#That's all based on the assumptions that tachyons even exist. To date, all
#Richard
#
#
Does anyone know who made up the word 'tachyon' and under what circumstances?
I understand that it comes from the greek 'tachos', for very fast. It would
be interesting to find out the scientific origin for this concept of a
hypothetical faster then light particle which is causing so much consternation
on the newsgroup.
Steve G
Steve Giblin
In article <Pine.GSO.3.95a.970401143646.19042T-100000@cms2>,
Anthony Potts <po...@cms.cern.ch> wrote:
#On Wed, 19 Jun 1996, Sandro Gisler wrote:
#
#> History shows that:
#>
#> Science considered speed of over 30 kph would be deadly for the human
body...
#> Until the railroad was invented.
#>
#
#That is not true.
#
#> Science considered moving faster than acoustic waves would be impossible
for mankind...
#> Until the jet plane was invented.
#>
#That is not true.
#
#
#> Science considered moving faster than light would be impossible for any
matter...
#> Until ... I don't know either, but remember that although our race is
gathering knowledge
#> faster than ever before, we don't know yet everything!
#>
#Please, you will have to try harder than that.
#
#
#Anthony Potts
#
#CERN, Geneva
#
I'd just like to add for the record that no-one ever thought faster than
sound motion was impossible. It was known since about 1880 that
rifle bullets travelled faster than sound. It was a tricky technical
problem to design planes that went faster than sound but it was only
a technical problem! the situation with regard to FTL is completely
different.
Steve G
Gordon D. Pusch
In article
<Forum.860169844.321...@OSF25.oklaosf.state.ok.us>
Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> writes:
> Great! Now, would you please explain to me what it means, in real
> physical terms, for a particle to have a mass given by the expression
> m*-1^0.5? Until you can, my point stands. Of course, taken out of
> context, my statement above is false. But, in the context of the
> "imaginary mass" of the tachyon, which I was discussing, it's not
> the same.
Richard, you should recall that withing relativity, ``mass'' is not
an observable, only energy and momentum --- and the energy and momentum
of a (admittedly hypothethical) tachyon turn out to be REAL-valued,
rather than complex numbers...
Trying to construct a theory that allows for interacting tachyons
causes an =ENORMOUS= number of logical problems --- not the least
of which are the apparent violations of both causality and the
2nd Law of Thermodynamics (for more detail, see Terletskii's
``Paradoxes in Relativity'') --- but the fact that certain
physically-unobservable quantities become formally imaginary
in such a theory is =NOT= one of them, in my opinion...
P.S. --- Richard, could you =PLEASE= start tossing in a hard carriage-
return somewhere around column 72 ??? Running everything together in
a single =ENORMOUSLY= long line as you do makes your posts a *little*
hard to read... :-/
-- Gordon D. Pusch <pu...@mcs.anl.gov>
Disclaimer: I'm a consultant --- I don't speak for ANL or the DOE,
and they *certainly* don't speak for =ME= !!!
Gordon D. Pusch
In article <E84GB...@fsa.bris.ac.uk> ph...@siva.bris.ac.uk
(Steve Giblin) writes:
> Does anyone know who made up the word 'tachyon' and under what
> circumstances? I understand that it comes from the greek 'tachos',
> for very fast. It would be interesting to find out the scientific
> origin for this concept of a hypothetical faster then light particle
> which is causing so much consternation on the newsgroup.
Gerald Feinberg, in his seminal paper ``On the possibility of
faster-than-light particles'' [Phys.Rev. v.159, pp.1089--1105 (1967)]
(BTW, according to charter, it *shouldn't* be in this Newsgroup,
or most of the *other* seven groups it's in --- it should be in
'sci.physics.relativity'...)
me...@cars3.uchicago.edu
Richard Caldwell
In Article Re: faster than light travel , Alan DeKok <aland@z[achilles.net]> wrote:
> [ extraneous newsgroups snipped ]
>
> In article <Forum.860105292.26...@OSF25.oklaosf.state.ok.us>,
> Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote:
> >
> > I know the mathematical definition of "imaginary" (* -1^0.5) but that's
> > an abstract mathematical concept.
>
> Like 1, or 2, or even 5.
I can show you 1, 2, or even 5 fingers. Can you show me -1^0.5 fingers?
My point is that some abstract mathematical concepts are easier to represent in ordinary, 3-dimensional reality than others are. The point being that you can write a mathematical expression for something that has no defined meaning in the real, physical world.
After all, mathematics is an ideal abstract system that is sometimes used to model physical things, but it is not limited to physical reality. In other words, just because you can write a mathematical expression for something doesn't mean it exists.
> > I don't know what it means in physical terms, so I call that "undefined".
>
> Perhaps you should try to use something other than your own personal
> naming convention.
Do you have a better word to mean "nobody knows what the Hell it means" than "undefined"? If so, I'll gladly use *your* personal naming convention. Note, I didn't use the word "undefined" in regard to the mathematical term. It was the physical reality of "imaginary mass" that I said was "undefined". Sorry if I didn't make myself clear.
> > If you do know what it means in
> > physical terms, pleas explain it to me.
>
> What does '1' mean in physical terms? You can't explain it.
It means a single unit of something. Not a tough concept to grasp.
> Sure, you can point to a rock, but it's just a rock. It doesn't
> physically signify '1'.
Of course not. Physical reality does *not* signify mathematical numbers or expressions. It's the other way around. Mathematics is used to signify physical reality, sometimes. Therefore the number 1, with the descriptor (or unit) "rock" behind it clearly indicates 1 rock. No problem. The rock doesn't symbolize anything. It simply *is*.
Now, my original question is this. If we are using mathematics to model the characteristics of particles, like protons, neutrons, electrons, neutrinos, etc. We say that there *might* be a particle that goes faster than light, lets call it a tachyon, but that it's mass is given by the expression (m*-1^0.5). What does that mean, in physical terms?
For that matter, what does negative mass mean? Anti-matter particles don't have negative mass. They have positive mass and the opposite electrical charge from their "normal" counterparts. I know such particles have been theorized, but I wonder what one would look/behave like, if we could put it in a bottle and study it.
Richard
me...@cars3.uchicago.edu
In article <Forum.860169844.321...@OSF25.oklaosf.state.ok.us>, Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> writes:
>
>In Article Re: faster than light travel , Richard Logan <rlo...@space.honeywell.com>
>> >
>> > That's my point, exactly. In mathematics, "imaginary" implies > undefined.
>>
>> is just the square root of -1. Imaginary numbers are used to describe
>> phase shifts (for instance, the phase shift in current and voltage
>> across a capacitor) among other useful things.
>
>
getting chopped.
Richard Caldwell
In Article Re: faster than light travel , "Gordon D. Pusch" <pu...@mcs.anl.gov> wrote:
> Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> writes:
>
> > Great! Now, would you please explain to me what it means, in real
> > physical terms, for a particle to have a mass given by the expression
> > m*-1^0.5? Until you can, my point stands. Of course, taken out of
> > context, my statement above is false. But, in the context of the
> > "imaginary mass" of the tachyon, which I was discussing, it's not
> > the same.
>
> Richard, you should recall that withing relativity, ``mass'' is not
> an observable, only energy and momentum --- and the energy and momentum
> of a (admittedly hypothethical) tachyon turn out to be REAL-valued,
> rather than complex numbers...
>
> Trying to construct a theory that allows for interacting tachyons
> causes an =ENORMOUS= number of logical problems --- not the least
> of which are the apparent violations of both causality and the
> 2nd Law of Thermodynamics (for more detail, see Terletskii's
> ``Paradoxes in Relativity'') --- but the fact that certain
> physically-unobservable quantities become formally imaginary
> in such a theory is =NOT= one of them, in my opinion...
Now *this* is what I call a relevant reply. Instead of nit-picking about the symantics
of terms like "imaginary" and "undefined", you actually tried to answer my question. I
appreciate your lack of pettiness.
To the subject, what you seem to be describing is a whole different kind of "reality",
where the very notion of "existence" is different from what we 3-dimensional critters
perceive and comprehend.
> P.S. --- Richard, could you =PLEASE= start tossing in a hard carriage-
> return somewhere around column 72 ??? Running everything together in
> a single =ENORMOUSLY= long line as you do makes your posts a *little*
> hard to read... :-/
Is this better? I recently upgraded my TCP/IP software, and the new newsreader has a
lot more settings than the old one. I found a box that tells it to put a CRLF at line
breaks when posting. I hope it improves my readability. Perhaps the truncation
problem is causing some of the misunderstanding of my posts.
Thanks for the tip.
Richard
me...@cars3.uchicago.edu
In article <Forum.860170392.12...@OSF25.oklaosf.state.ok.us>, Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> writes:
>
>In Article Re: faster than light travel , "thomas.kalbfus" <thomas....@MCIONE.com> wrote:
>
>> But if tachyons and Baryons can interact with each other, then real time
>
>
Jay Denebeim
In article <Forum.860169844.321...@OSF25.oklaosf.state.ok.us>,
Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote:
> Great! Now, would you please explain to me what it means, in real
> physical terms, for a particle to have a mass given by the
> expression m*-1^0.5?
Oh, that's an easy one. Any real mass near an imaginary mass is
subject to non-sensical random events and is unable to proceed for
more than an hour without ending up exactly where it started.
Jay
--
* Jay Denebeim, Moderator, rec.arts.sf.tv.babylon5.moderated *
* newsgroup submission address: b5...@deepthot.cary.nc.us *
* moderator contact address: b5mod-...@deepthot.cary.nc.us *
* personal contact address: dene...@deepthot.cary.nc.us *
Wayne Throop
Discussing what "imaginary mass" or "imaginary proper time" might mean.
::: I know the mathematical definition of "imaginary" (* -1^0.5) but
::: that's an abstract mathematical concept.
:: Like 1, or 2, or even 5.
: I can show you 1, 2, or even 5 fingers. Can you show me -1^0.5 fingers?
: My point is that some abstract mathematical concepts are easier to
: represent in ordinary, 3-dimensional reality than others are. The
: point being that you can write a mathematical expression for something
: that has no defined meaning in the real, physical world.
First of all, the physical interpretation of "imaginary" in the physical
world is normally "an orthogonal vector". That is, associated with the
number plane in stead of the number line. It turns out to be physically
meaningful in lots and lots of situations, from electrical engineering to
bridge building. Not really esoteric and conceptual at all.
But on the other hand.
The specific situations where imaginary numbers come up in SR for
FTL travel are real problems. Especially the "imaginary rest mass"
needed for tachyons: rest mass is a scalar, not a vector; turning
rest mass into a vector willy nilly is fairly problematical.
Feinberg did it when he coined the term "tachyon", but (IMHO) largely
by simply ignoring the problem instead of really resolving it.
Turning *time* into a vector as Hawking does is less problematical.
But doing it in the context of locally-SR-flat-spacetime as needed
for FTL at the scale of stellar distances and human lifetimes is
*not* any less problematical. The spacetime metric is a pythagorean-
theorem-like relationship between proper time, coordinate time, and
coordinate distance. The notion of "going faster than light" is
a notion much like "having a right triangle with the hypotenuse
shorter than another of the sides". The third side would have
an "imaginary length", but there's no vector interpretation of this.
Similarly with FTL: there's no consistent interpretation of the
imaginary passage of time that's involved in an FTL trajectory
in the usual sense.
The point being, I agree with Richard Caldwell: simply making the
equation come out right isn't quite enough to give a physical meaning to
the equation with those values. Just as in the triangle discussed above.
This doesn't render FTL "totally and completely unthinkable", or any such
radical thing. It's just that it's not as trivial as saying "Oh, the mass
turns out imaginary? So it turns out imaginary, la-de-da!".
--
Wayne Throop thr...@sheol.org http://sheol.org/throopw
thr...@cisco.com
Francis Litterio
Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote:
> > phenomonon such as wormholes are widely theorized by physicists as existing in
> > a variety of forms, and it has been suggested that some such wormholes may
> > even be traversable. By taking a shortcut through another dimention, it may
> > be possible to circumvent the "speed of light" without ever violating
> > relativity or making it invalid.
> Agreed, and I sure hope you are right. Otherwise, we're stuck in a pretty small
> neighborhood. 8-[
It's a common misconception that the speed of light barrier prevents
us from travelling great distances in short amounts of proper time.
With a sufficiently large expenditure of engery, rapid interstellar
travel within one's lifetime is possible. If you travel fast enough,
it is possible to get from Earth to Alpha Centauri (four light years
distant) with only three months of food, water, and air on the ship.
None of this contradicts Special Relativity. Just get ready to say
goodbye to friends and familly forever (or take them with you).
--
Francis Litterio PGP Key Fingerprint:
fr...@world.RemoveThis.std.com 02 37 DF 6C 66 43 CD 2C
http://world.std.com/~franl/ 10 C8 B5 8B 57 34 F3 21
Email address altered to protect against spamming.
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety." -- Ben Franklin, ~1784
me...@cars3.uchicago.edu
In article <3344FF...@oregoncoast.com>, The Spy <s...@oregoncoast.com> writes:
>Richard Caldwell wrote:
>>>>The light speed barrier is not technical barrier, not an engineering
>>>>barrier, but a local speed limit throughout the whole universe.
>>>>
>>>>Yes, the theory might be incorrect, but there is definitely something
>>>>going on at light speed, and making better rockets will never take us past
>>>>that limit.
>
>I read that as you approach the speed of light, matter and energy become
>interchangeable. Any attempt at reaching the speed of light would cause a
>breakdown of the entire ship.
No.
George Herbert
Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote:
>> >That's my point, exactly. In mathematics, "imaginary" implies undefined.
>> >meaningless.
>My, my! This thread is full of mathematicians who read that one sentence,
>evidently out of context, and jumped all over it.
>OK, I STAND CORRECTED. THE TERM "IMAGINARY" IS VERY WELL DEFINED
>IN MATHEMATICS.
Well, your origional statement, taken as literally written, indicated
a profound misunderstanding of complex and imaginary numbers...
however, I can easily understand you having not meant that.
I consider it a good year that I don't make a mind-numbingly
glaring mistake in a serious technical posting to a technical
Usenet group... and have had precious few good years since 1987.
>Of course, that defintion tells us nothing about the physical reality
>of a particle that has "imaginary mass", so the original meaning of what
>I said still stands. I will rephrase it:
>
>If a particle has an "imaginary mass", as defined in mathematics,
>this implies that the mass of the particle is "undefined" in any real,
>physical sense.
>
>Does that satisfy you nit-picking mathematicians? 8-]
I suggest you look around at the speculations that physicists
were making when the neutrino appeared to have imaginary mass.
[Specifically, measuring it's total energy in a particular way
to try and find its rest energy and thence rest mass,
some measurements indicated a negative rest energy which
should imply imaginary rest mass, as I remember the report]
More recent reports appear to contradict those observations
but they haven't been entirely repudiated yet that I know of.
I don't regularly read all the right physics journals and
newsgroups, though, so please correct if this has changed 8-)
I saw someone mention interpreting it as a swap of one of the space
dimentions and the time dimention in the neutrino's reference frame,
similarly to what happens at the event horizon of a black hole.
-george william herbert
Retro Aerospace
gher...@crl.com
Sylvia Else
The Spy wrote:
> I read that as you approach the speed of light, matter and energy become
> interchangeable. Any attempt at reaching the speed of light would cause a
> breakdown of the entire ship.
Matter and energy are the same thing anyway. As for the ship breaking
down - from the point of view of the ship, nothing changes internally as
its velocity relative to the 'static' universe increases. Colliding with
particles and more substantial objects at those sorts of speeds tend to
spoil the polished finish, though.
Sylvia.
amol dighe
In article <5i17qn$8...@mars.hyperk.com>, hwk...@REVOVE2REPLYpoky.srv.net (Alan Kohler) writes:
|>
|> Let me emphasize a point that you and some other equally unatentive posters
|> seemed to have missed: I'm not suggesting that a VELOCITY greater than light
|> is possible. What I am suggesting is that it MAY BE possible for an object to
|> "traverse" a distance between 2 points in a shorter time than light would.
|> There are some highly qualified theoretical physicists who have some
|> facinating theories on wormholes and their paractical contruction (esp.
|> Michael Morris, Kip Thorne, and Matt Visser). Just because we cannot
|> explicity prove these theories today does not mean they are not possible.
In fact, no need to go to wormholes for this. Inside material medium,
where the speed of light is less than c, particles can travel faster than
light [in that medium] - though not faster than c, of course. And this is
observed. [Refer to any discussion about Cerenkov radiation].
But how does this contradict anything in SR ?
Simon Cast
Richard Caldwell wrote:
>
> Since nobody knows what "the other side" might be like, your guess (and that's all it is) is as good as anybody's. 8-]
>
> Richard
I never said that it wasn't but on the same note there is nothing to say
that it couldn't be a possibilty. I guess that it gives a theoretical
mathematician or physicst something to fill in there spare time.
Simon
I H Spedding
On Fri, 4 Apr 1997 22:21:49 GMT, ph...@siva.bris.ac.uk (Steve Giblin)
wrote:
>#That's all based on the assumptions that tachyons even exist. To date, all
>experiments to detect tachyons, or their effects, have had negative results.
>#
>#Richard
>#
>#
>Does anyone know who made up the word 'tachyon' and under what circumstances?
>I understand that it comes from the greek 'tachos', for very fast. It would
>be interesting to find out the scientific origin for this concept of a
>hypothetical faster then light particle which is causing so much consternation
>on the newsgroup.
My understanding is that the term "tachyon" was coined by Gerald
Feinberg of Columbia University.
Apparently, particles which exist only at FTL speeds are allowed by
relativity theory. Physicists are in the habit of assuming that
anything not specifically forbidden by theory must exist and have
been looking for signs of the elusive little beasties - thus far,
unsuccessfully.
Ian
-----------------------------------------------------------------------
Ian H Spedding (sped...@mognet.u-net.com)
There is certainly nothing impossible about abduction by aliens in
UFO's. But on the grounds of probability it should be kept as an
explanation of last resort. It is unparsimonious, demanding more than
routinely weak evidence to support it.
Richard Dawkins: Richard Dimbleby Lecture (12 November 1996)
-----------------------------------------------------------------------
Simon Cast
me...@cars3.uchicago.edu wrote:
> >
> >That's all based on the assumptions that tachyons even exist. To date, all experiments to detect tachyons, or their effects, have had negative results.
> >
>
Why shouldn't they exist? Does it really need a reason to exist?
Simon
Sherilyn
In article <Pine.GSO.3.95a.970401143646.19042T-100000@cms2>, Anthony
>On Wed, 19 Jun 1996, Sandro Gisler wrote:
>
>>
>> Science considered speed of over 30 kph would be deadly for the human body...
Science considered bullshit was limited to the speed of the bull.
Until USENET was invented.
--
Sherilyn
John D. Gwinner
Folks:
There's an even more concrete realization of imaginary components, and
that's in electrical engineering. Solving maxwell's equations for certain
types of components (inductors and capacitors with certain waveforms)
generally makes use of i -- you find imaginary numbers used all over the
place in this type of electrical engineering. (Sine waves for example).
So, as your computer uses AC power, you couldn't read this if it weren't
for imaginary numbers; the math used in picking the components for your
monitor or power supply at some point relied on i
== John ==
John D. Gwinner
Richard:
> > Don't confuse the inadequate colloquial English term 'imaginary' with
> > the mathematical definition of 'i'.
>
> I'm not confusing anything. I am well aware of the mathematical
> definition of "imaginary". However, this is an abstract, mathematical
> definition. It tells us *nothing* about the real physical
> characteristics of a particle that has an "imaginary mass".
> Therefore, in the physical sense, such a mass is undefined.
Not true at all; abstract mathematical definitions of i are extremely
important, or your TV set would have blown up a long time ago.
i is used quite a bit in certain types of electrical engineering when
working with AC waveforms. So (as even laptops running on batteries need
AC when working with LCD screens) if you are reading these letters, you are
seeing a concrete non-abstract use of i
i mass I don't know about; we return you to your previously scheduled
debate <G>
== John ==
Dan Evens
Simon Cast wrote:
[referring to tachyons]
> Why shouldn't they exist? Does it really need a reason to exist?
Tachyons are generally considered to be a pathological aspect of
a field theory. Tachyon states allow negative energy of arbitrary
value. This is often referred to as unstable vacuum. Out of
nothing you can produce an arbitrary number of tachyons of
arbitrary energy. The result would be an explosion of particles
of all types from all directions and locations. All the time.
For all time.
This does not SEEM to be happening, so people are suspicious of
any theory containing tachyons.
Dan Evens
Dan Evens
This is slightly misleading. You could certainly do the same
calculation using matrices and vector representations, at least
at a classical (that is, non quantum) level. In this case, the
insertion of i is very nearly only a convenience. The point is,
the imaginary number system is isomorphic to a different set of
objects which can be used to represent the same physical thing.
This kind of thing is usual in much of physics. We don't absolutely
HAVE to use imaginary numbers. It's just that it is amazingly more
easy to use them in many cases.
Dan Evens
me...@cars3.uchicago.edu
In article <334631...@student.uq.edu.au>, Simon Cast <s34...@student.uq.edu.au> writes:
>me...@cars3.uchicago.edu wrote:
>> >
>> >That's all based on the assumptions that tachyons even exist. To date, all experiments to detect tachyons, or their effects, have had negative results.
>> >
>> Moreover, nobody even came with a good reason why should they exist.
>>
>
>
particles was postulated for experimental or theoretical reasons. Few
cases of the sort are:
1) The neutrino: Postulated by Pauli based on observed non
conservation of energy, momentum and angular momentum in beta decays.
2) The positron: Postulated (sorta) by Dirac based on his
relativistic equation.
3) The omega minus: Postulated independently by Gel-Man and Neeman
based on an observation of specific regularity in the grouping of
hyperons (heavy barions).
What all these cases had in common was that you could observe some
pattern, either theoretical or experimental and this pattern indicated
that there is a missing piece in the puzzle. Just like Mendeleyev
predicted the existance of some yet unobservad (at his time) elements
based on his periodic table. That's what I call "reason for
existance". There is nothing like this regarding tachyons.
Harry H Conover
Sherilyn (sher...@sidaway.demon.co.uk) wrote:
:
: Science considered bullshit was limited to the speed of the bull.
: Until USENET was invented.
Roger that!
Harry C.
me...@cars3.uchicago.edu
In article <01bc41ef$1a91c040$265ee8cd@sal9000>, "John D. Gwinner" <gwi...@northnet.org> writes:
>Folks:
>
> There's an even more concrete realization of imaginary components, and
>that's in electrical engineering. Solving maxwell's equations for certain
>types of components (inductors and capacitors with certain waveforms)
>generally makes use of i -- you find imaginary numbers used all over the
>place in this type of electrical engineering. (Sine waves for example).
>
> So, as your computer uses AC power, you couldn't read this if it weren't
>for imaginary numbers; the math used in picking the components for your
>monitor or power supply at some point relied on i
>
are performed using complex functions could be performed (albeit in a more
awkward fashion) using purely real notation. It is a matter of
convenience, not necessity, in this case.
Harry H Conover
Dan Evens (dev...@inforamp.net) wrote:
:
: This is slightly misleading. You could certainly do the same
: calculation using matrices and vector representations, at least
: at a classical (that is, non quantum) level.
You first!
A 100-Volt battery is connected though an open switch to a series
circuit consisting of a 50-Ohm resistor, a 5-mFd. capacitor, and
a 500-mHy inductor. The capacitor is initially uncharged.
Compute (using matrices and vector representations), the current
through the circuit (as a function of time) from switch closure
until equilibrium conditions are achieved. (Consider all the
components to be ideal.)
Computers and calculators are not allowed, and please show
your work.
Harry C.
p.s. This is a standard 1st or 2nd year undergraduate EE problem
in a.c. circuits. I have never seen a solution that did not
involve differential equations and imaginary numbers (actually
complex numbers) but am willing to learn!
Tim Hollebeek
In article <334631...@student.uq.edu.au>, Simon Cast <s34...@student.uq.edu.au> writes:
> me...@cars3.uchicago.edu wrote:
> > >
> > >That's all based on the assumptions that tachyons even exist. To date, all experiments to detect tachyons, or their effects, have had negative results.
> > >
> > Moreover, nobody even came with a good reason why should they exist.
> >
>
> Why shouldn't they exist? Does it really need a reason to exist?
Yes. Calculations show that without a reason to exist, the vast majority
of tachyons would have committed suicide shortly after the Big Bang, and
certainly none would still be around some billions of years later.
---------------------------------------------------------------------------
Tim Hollebeek | Disclaimer :=> Everything above is a true statement,
Electron Psychologist | for sufficiently false values of true.
Princeton University | email: t...@wfn-shop.princeton.edu
----------------------| http://wfn-shop.princeton.edu/~tim (NEW! IMPROVED!)
Matt Austern
fr...@world.std.REMOVETHIS.com (Francis Litterio) writes:
> With a sufficiently large expenditure of engery, rapid interstellar
> travel within one's lifetime is possible. If you travel fast enough,
> it is possible to get from Earth to Alpha Centauri (four light years
> distant) with only three months of food, water, and air on the ship.
> None of this contradicts Special Relativity. Just get ready to say
> goodbye to friends and familly forever (or take them with you).
Ever done the calculation to find out just how large that
"sufficiently large" is? It's enlightening. (And depressing.)
You might want to consider the following setup. Suppose you have a
100% efficient drive. (Imagine matter+antimatter -> photons, for
example.) Suppose you want to get to Alpha Centauri, with constant
1g acceleration. That is, you accelerate at 1g until you're halfway
there, then you turn your drive around and slow down, again at 1g.
This trip turns out to take about three years ship time, and five
years Earth time. Question: what fuel-to-payload ratio do you have to
start out with? (Remember that you always have to accelerate the fuel
that you haven't burned yet...)
Avital Pilpel
Tim Hollebeek wrote:
>
> Yes. Calculations show that without a reason to exist, the vast majority
> of tachyons would have committed suicide shortly after the Big Bang, and
> certainly none would still be around some billions of years later.
>
> ---------------------------------------------------------------------------
> Tim Hollebeek | Disclaimer :=> Everything above is a true statement,
> Electron Psychologist | for sufficiently false values of true.
> Princeton University | email: t...@wfn-shop.princeton.edu
> ----------------------| http://wfn-shop.princeton.edu/~tim (NEW! IMPROVED!)
I think that the interest in the theoretical entities called tachions, not to
mention complete faith in their "scientific existence", is actually mainly
based on the fact that the Enterprise in "Star Trek" on TV "uses" tachyons for
propulsion... :-)
--
Avital Pilpel.
=====================================
The majority is never right.
-Lazarus Long
=====================================
Mark P. Line
Gordon D. Pusch wrote:
>
> P.S. --- Richard, could you =PLEASE= start tossing in a hard carriage-
> return somewhere around column 72 ??? Running everything together in
> a single =ENORMOUSLY= long line as you do makes your posts a *little*
> hard to read... :-/
I just assumed he'd been using imaginary carriage returns.
-- Mark
(Mark P. Line -- Bellevue, Washington -- <ml...@ix.netcom.com>)
Alan Kohler
In article <5i6ge2$n...@news.inforamp.net>, dev...@inforamp.net says...
>
>John D. Gwinner wrote:
>>
>> Folks:
>>
>> There's an even more concrete realization of imaginary components, and
>> that's in electrical engineering. Solving maxwell's equations for certain
>> types of components (inductors and capacitors with certain waveforms)
>> generally makes use of i -- you find imaginary numbers used all over the
>> place in this type of electrical engineering. (Sine waves for example).
>>
>> So, as your computer uses AC power, you couldn't read this if it weren't
>> for imaginary numbers; the math used in picking the components for your
>> monitor or power supply at some point relied on i
>
>calculation using matrices and vector representations, at least
>insertion of i is very nearly only a convenience. The point is,
>the imaginary number system is isomorphic to a different set of
>objects which can be used to represent the same physical thing.
>
>This kind of thing is usual in much of physics. We don't absolutely
>HAVE to use imaginary numbers. It's just that it is amazingly more
>easy to use them in many cases.
Are far as most people dealing with electrcity are concerned, imaginary number
notation and cartesian coordinates are essentially identical - however,
there's a reason that electical engineering problems usally include "j" (EEs
use "j" for -1^.5 rather than "i", BTW) becasue of the derivation of wave
functions in electronics (or in any field - electromagnetic radiation is
similar).
That reason is that while you can represent these fuctions with vectors, its
really just a simplification of what's really happend by means of what's known
as a "fourier transformation" or a tranformation between time and frequency
domains. When analyzing these functions, you get a lot of 2nd order
differential equations. These equations behave sort of like polynomials - and
like polynomials, you can end up with solution with imaginary roots. However,
unlike most polynomials, these imaginary numbers mean something, and can be
related by "euler's identity" to more familiar sines and cosines - which
describe waveforms that are also more familiar to anyone with any knowledge of
physical sciences.
The above paragraph might be beyond those without backgrounds in math,
physics, or engineering, but that point is this: imaginary numbers are not
just convenient representations, thay represent the "guts" of what's going on.
Contrary to what the above poster said, we DO have to use imaginary numbers
when we are describing phase shifts in wave fuctions - at least at the most
basic levels.
What bearing this has on tachyons, I'm not sure. Relativistic plots of mass
and energy have little to do with wave fuctions as I know it, but there may be
some obsure yet to be discovered theorom that is currently beyond are grasp
that makes meaning of the term "imaginary mass". Just maybe.
--
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is greater, for each violation."
Simon Cast
me...@cars3.uchicago.edu wrote:
>
> In article <334631...@student.uq.edu.au>, Simon Cast <s34...@student.uq.edu.au> writes:
> >me...@cars3.uchicago.edu wrote:
> >> >
> >> >That's all based on the assumptions that tachyons even exist. To date, all experiments to detect tachyons, or their effects, have had negative results.
> >> >
> >> Moreover, nobody even came with a good reason why should they exist.
> >>
> >
> >Why shouldn't they exist? Does it really need a reason to exist?
> >
> particles was postulated for experimental or theoretical reasons. Few
> cases of the sort are:
>
> 1) The neutrino: Postulated by Pauli based on observed non
> conservation of energy, momentum and angular momentum in beta decays.
>
> 2) The positron: Postulated (sorta) by Dirac based on his
> relativistic equation.
>
> 3) The omega minus: Postulated independently by Gel-Man and Neeman
> based on an observation of specific regularity in the grouping of
> hyperons (heavy barions).
>
> What all these cases had in common was that you could observe some
> pattern, either theoretical or experimental and this pattern indicated
> that there is a missing piece in the puzzle. Just like Mendeleyev
> predicted the existance of some yet unobservad (at his time) elements
> based on his periodic table. That's what I call "reason for
> existance". There is nothing like this regarding tachyons.
>
> me...@cars.uchicago.edu | chances are he is doing just the same"
I stand corrected.
Here's another question. Could the idea of tachyons be right but the
application of tachyons in theories be incorrect? In other words could
tachyons exist but we are looking in the wrong place and at the wrong
things to find them?
Simon
Alan Kohler
In article <E86sD...@midway.uchicago.edu>, me...@cars3.uchicago.edu says...
>>
>> There's an even more concrete realization of imaginary components, and
>>that's in electrical engineering. Solving maxwell's equations for certain
>>types of components (inductors and capacitors with certain waveforms)
>>generally makes use of i -- you find imaginary numbers used all over the
>>place in this type of electrical engineering. (Sine waves for example).
>>
>> So, as your computer uses AC power, you couldn't read this if it weren't
>>for imaginary numbers; the math used in picking the components for your
>>monitor or power supply at some point relied on i
>>
>are performed using complex functions could be performed (albeit in a more
>awkward fashion) using purely real notation.
This is WRONG. The only way we can relate time and frequency domains of a
wave function is by a fourier transformation and euler's identity, which
requires the use of imaginary numbers.
me...@cars3.uchicago.edu
In article <334709...@student.uq.edu.au>, Simon Cast <s34...@student.uq.edu.au> writes:
>
>Here's another question. Could the idea of tachyons be right but the
>application of tachyons in theories be incorrect? In other words could
>tachyons exist but we are looking in the wrong place and at the wrong
>things to find them?
>
let whoever knows better correct it): The idea of tachyons, in
combination with our current physical theories, gives rise to some
predictions which were not experimentally observed. Now, does it rule
out tachyons all together? No. Our theories may be incomplete, they
may not be applicable to the realm in question, etc. We look where
our knowledge directs us to look, so yes, we may be looking at the
wrong things. But so far, there isn't much in physics to support the
notion that tachyons exist.
me...@cars3.uchicago.edu
In article <5i71n7$n...@mars.hyperk.com>, hwk...@REVOVE2REPLYpoky.srv.net (Alan Kohler) writes:
>In article <E86sD...@midway.uchicago.edu>, me...@cars3.uchicago.edu says...
>>
>>In article <01bc41ef$1a91c040$265ee8cd@sal9000>, "John D. Gwinner"
><gwi...@northnet.org> writes:
>>>
>>> So, as your computer uses AC power, you couldn't read this if it weren't
>>>for imaginary numbers; the math used in picking the components for your
>>>monitor or power supply at some point relied on i
>>>
>>This is not quite true. All the electrodynamical calculations that
>>are performed using complex functions could be performed (albeit in a more
>>awkward fashion) using purely real notation.
>
>This is WRONG. The only way we can relate time and frequency domains of a
>wave function is by a fourier transformation and euler's identity, which
>requires the use of imaginary numbers.
>
cosine functions, within the real domain. It is terribly cumbersome
and very counterproductive as far as ease of insight is considered,
but mathematically it is perfectly possible. Wouldn't recommend it to
anybody, though.
me...@cars3.uchicago.edu
And, till you get this perfect drive, calculate the fuel to payload
ratio needed for a rocket using the best chemical rocket available
(exhaust velocity 5 km/s) in order to get to a mere 1000 km/s
velocity (corresponding to accelerating at 1 g for a bit more then a
day).
William L. Bahn
Harry H Conover <con...@tiac.net> wrote in article
<5i6npl$m...@news-central.tiac.net>...
>
>
> Dan Evens (dev...@inforamp.net) wrote:
> :
> : This is slightly misleading. You could certainly do the same
> : calculation using matrices and vector representations, at least
> : at a classical (that is, non quantum) level.
>
> You first!
>
> A 100-Volt battery is connected though an open switch to a series
> circuit consisting of a 50-Ohm resistor, a 5-mFd. capacitor, and
> a 500-mHy inductor. The capacitor is initially uncharged.
>
> Compute (using matrices and vector representations), the current
> through the circuit (as a function of time) from switch closure
> until equilibrium conditions are achieved. (Consider all the
> components to be ideal.)
>
> Computers and calculators are not allowed, and please show
> your work.
>
> Harry C.
>
> p.s. This is a standard 1st or 2nd year undergraduate EE problem
> in a.c. circuits. I have never seen a solution that did not
> involve differential equations and imaginary numbers (actually
> complex numbers) but am willing to learn!
>
>
I couldn't find Mr. Evens' post about matrices and vector representations,
but from the other posts in this thread I gather that the point is whether
imaginary mass (in the case of tachyons) has physical meaning. The claim
has been put forth that because imaginary and complex numbers are used in
describing physical systems that there is the implication that they can, in
fact, have physical meaning.
As a person who has taught intro EE and the solving of these types of
problems, let me tell you that there is NO need for imaginary (or complex)
numbers to obtain a solution. Differential Equations, yes, because you are
dealing with a system whose components have constitutive equations that
involve time differentials of the state variables. But none of that
REQUIRES complex numbers to obtain a solution.
So, you might ask, if we don't need complex numbers, why do we invariably
use them? Simple, it makes the math a hell of a lot easier! Exponential
functions are so well behaved (in this context, I mean only 'easy to
manipulate') with respect to multiplication, division, integration and
differentiation compared to sines and cosines that the ability to write a
sine (or cosine) function in terms of an exponential function drastically
simplifies the mathematical gyrations. The fact that complex numbers must
be used to employ this approach is merely an artifact of the mathematics.
But, are we using complex quantities to mean physical quantities? NO! If I
say that Jane walks -(2i)(0.5i) miles to school, have I implied that
imaginary distances have meaning? NO! As long as the imaginary and complex
values always appear in our answers in such a way as to evaluate to a real
quantity then no such claim is expressed or implied. If you look VERY
CAREFULLY at the use of complex values in the description and analysis of
real systems, you will find that the above condition ALWAYS holds true.
What we have done, in the name of simplifying the bookkeeping, is to
acknowledge that we are really only working with a part of the full
expression because we know how to deal with the result at the end.
For instance, say I have the function f=Asin(wt+q). I can write this as
f=Im(A(cos(wt+q)+isin(wt+q))=Im(A*e^(i(wt+q)))=Im(F(w)) where
F=A*e^(i(wt+q))
If I stipulate that it is understood that, once I get done, I must take the
Imaginary part of my answer because that is where I imbedded the very real
initial function, then I can work with F(w) in all of my calculations. But,
at no time am I ever claiming that the complex function F(w) itself has
physical meaning.
Personally, when developing the use of complex exponentials in circuit
analysis, I prefer to write the initial function in the form
f=Asin(wt+q)=(A/2)[e^(i(wt+q))+e^(-i(wt+q))]
This way, at NO TIME are you ever working with a complex function. You are
working with a real function that happens to be written in terms of complex
quantities but which, never-the-less, evaluates to a real value at every
point in its domain.
Whenever I teach this course, I have to fight the resistance that the
students have to working with complex numbers and exponentials. Most have a
very limited background in complex math and far too many have pitifully
weak math skills in general. So, after developing all of the theory that
allows the use of complex math to analyze these problems and tolerating all
the moaning and groaning about having to learn a new, harder way when they
already know how to do differential equations, I work a simple RC function
with sinusoidal driving voltage both ways in all of its gory detail. Using
direct differential equations, the solution takes about 30 minutes and
covers the entire blackboard. Using complex math, the solution takes three
lines and less than 30 seconds. I seldom hear any more complaints.
John D. Gwinner
Dan:
Dan Evens <dev...@inforamp.net> wrote in article
<5i6ge2$n...@news.inforamp.net>...
> John D. Gwinner wrote:
> >
> > Folks:
> >
> > There's an even more concrete realization of imaginary components,
and
> > that's in electrical engineering. Solving maxwell's equations for
certain
> > types of components (inductors and capacitors with certain waveforms)
> > generally makes use of i -- you find imaginary numbers used all over
the
> > place in this type of electrical engineering. (Sine waves for
example).
> >
> > So, as your computer uses AC power, you couldn't read this if it
weren't
> > for imaginary numbers; the math used in picking the components for your
> > monitor or power supply at some point relied on i
>
> This is slightly misleading. You could certainly do the same
> calculation using matrices and vector representations, at least
> at a classical (that is, non quantum) level. In this case, the
> insertion of i is very nearly only a convenience. The point is,
> the imaginary number system is isomorphic to a different set of
> objects which can be used to represent the same physical thing.
>
> This kind of thing is usual in much of physics. We don't absolutely
> HAVE to use imaginary numbers. It's just that it is amazingly more
> easy to use them in many cases.
> Dan Evens
It's been nearly fifteen years since I worked through these equations, and
it wasn't my specialty in EE, so some of this is a bit murky. However,
matrices ARE used. The i's in there are part of the matrices as near as I
remember. The size of the matrix is nxn with n being the number of
components in the circuit.
I don't have any of my old textbooks (had to give them back to Uncle Sam,
some 'paid scholarship' that was), so I can't comment in detail.
In any event, you may be right, there are often several ways of describing
something. But Occam's razor comes into play here also, as you point out.
== John ==
Gordon D. Pusch
In article <01bc424f$4f40d5f0$50664ccf@BAHN> "William L. Bahn"
<ba...@pcisys.net> writes:
[...snip of =EXCELLENT= pedagogical discussion of why complex numbers
are used to *simplify* certain problems, but are =NOT= _necessary_ to
solve them, and should not be taken to imply a ``physical'' meaning
for complex-valued quantities...]
...To which I only want to add that =ALL= such problems I personally
know of, the physical systems in question are =LINEAR=. Because
complex numbers are a LINEAR combination of ``real'' and ``imaginary''
quantities 'a + ib' in LINEAR systems, it is legitimate to to extend
the problem into the complex plane, then extract just the REAL part
at the end of the calculation to get the *physical* part of the answer.
In NON-linear systems, however, this ``complex-analytic extension''
process fails to be so simple, due to NON-linear mixing between the
``real'' and ``imaginary'' parts of the solution. Hence, in NON-linear
systems (which are actually dominant class of systems in the Universe),
complex numbers cease to be as convenient, and are much less often used.
IMO, the only really *impressive* attemp at assigning a ``physical''
meaning to ``complex'' numbers is David Hestenes' ``Spacetime algebra''
programme for a consistent and unified reformulation of all of physics
in terms of ``Clifford algebras'' (as opposed to the current, ad-hoc
mish-mash of vectors, tensors, spinors, and complex numbers). He finds
that in =ALL= the cases he's considered, the ``imaginary unit'' sqrt(-1)
can be interpreted as the Clifford-algebraic generator of a rotation.
(For example, the ``phase'' of the Schroedinger wavefunction can be
related to the electron's *spin*, in the limit that spin-precession
may be neglected.)
For more on Hestenes' work, see:
Hestenes, D. -- ``Space-Time Algebra,'' Gordon & Breach (1966)
Hestenes, D. & Sobczyk, G. -- ``Clifford Algebra to Geometric
Calculus: A Unified Foundation for Mathematics and Physics,''
Reidel (1984) [Note: =VERY= heavy going, mathematically,
and unfortunately contains numerous misprints --- but it
has an =EXCELLENT= bibliography...]
Hestenes, D. & Sobczyk, G. -- ``New Foundations for Classical
Mechanics'' Reidel (1988) [Note: This textbook is =VERY=
readable, and would be *emminantly* suitable for an Under-
graduate course, if it weren't so bleeding *expensive*... :-( ]
Baylis, Wm. (ed.) -- ``Clifford (Geometric) Algebras, With
Applications in Physics, Mathematics, and Engineering''
Birhauser (1996).
-- Gordon D. Pusch <pu...@mcs.anl.gov>
Disclaimer: I'm a consultant --- I don't speak for ANL or the DOE,
and they *certainly* don't speak for =ME= !!!
John D. Gwinner
me...@cars3.uchicago.edu wrote in article
<E874I...@midway.uchicago.edu>...
... lot's of refs snipped
> >>> So, as your computer uses AC power, you couldn't read this if it
weren't
> >>>for imaginary numbers; the math used in picking the components for
your
> >>>monitor or power supply at some point relied on i
> >>>
> >>This is not quite true. All the electrodynamical calculations that
> >>are performed using complex functions could be performed (albeit in a
more
> >>awkward fashion) using purely real notation.
...
> Nah. You can do all your fourrier transformations using sine and
> cosine functions, within the real domain.
But that doesn't change the facts; the values chosen in your computer's
power supply DID use i at some point. Engineers are practical; they use
the simplest solution that's accurate enough, and this almost certainly
involved 'i' at some point.
So I still stand by my statement; imaginary numbers put these letters on
the screen!
== John ==
P.S. If you still disagree, you're welcome to design a computer from the
ground up using only matrices, sine, and cosine's with real components (as
opposed to sine's of i components) and sell it on the marketplace. I bet
the cost of it will be extremely high due to the design costs. Good luck!
me...@cars3.uchicago.edu
In article <01bc429d$bbaeb920$2d5ee8cd@sal9000>, "John D. Gwinner" <gwi...@northnet.org> writes:
>
>me...@cars3.uchicago.edu wrote in article
><E874I...@midway.uchicago.edu>...
>
>... lot's of refs snipped
>
>> >>> So, as your computer uses AC power, you couldn't read this if it
>weren't
>> >>>for imaginary numbers; the math used in picking the components for
>your
>> >>>monitor or power supply at some point relied on i
>> >>>
>> >>This is not quite true. All the electrodynamical calculations that
>> >>are performed using complex functions could be performed (albeit in a
>more
>> >>awkward fashion) using purely real notation.
>
>...
>
>> Nah. You can do all your fourrier transformations using sine and
>> cosine functions, within the real domain.
>
>But that doesn't change the facts; the values chosen in your computer's
>power supply DID use i at some point. Engineers are practical; they use
>the simplest solution that's accurate enough, and this almost certainly
>involved 'i' at some point.
>
post that it would've been silly and counterproductive not to do so.
I just want to make clear the difference between things we do because
physical reality forces us to do them, versus things we do due to
convenience considerations. One should always be able to distinguish
between the principles and the technicalities of what one is doing.
Simon Cast
Avital Pilpel wrote:
>
> I think that the interest in the theoretical entities called tachions, not to
> mention complete faith in their "scientific existence", is actually mainly
> based on the fact that the Enterprise in "Star Trek" on TV "uses" tachyons for
> propulsion... :-)
>
> --
> Avital Pilpel.
>
> =====================================
> The majority is never right.
>
> -Lazarus Long
> =====================================
Watch more Star Trek. Propulsion is not by tachyons or tachions
(although they do use it for other uses i.e. sensor nets etc.). I wont
go into the "theory" of Star Trek propulsion as I think it is way of
topic (would it be?) for this group.
Simon
Dries van Oosten
On Mon, 7 Apr 1997, Simon Cast wrote:
> Avital Pilpel wrote:
> >
> > I think that the interest in the theoretical entities called tachions, not to
> > mention complete faith in their "scientific existence", is actually mainly
> > based on the fact that the Enterprise in "Star Trek" on TV "uses" tachyons for
> > propulsion... :-)
> >
> > --
> > Avital Pilpel.
> >
> > =====================================
> > The majority is never right.
> >
> > -Lazarus Long
> > =====================================
>
> Watch more Star Trek. Propulsion is not by tachyons or tachions
> (although they do use it for other uses i.e. sensor nets etc.).
Agreed
> I wont
> go into the "theory" of Star Trek propulsion as I think it is way of
> topic (would it be?) for this group.
Agreed
>
> Simon
>
>
Dries van Oosten
Eat any good books lately?
Richard Caldwell
In Article Re: faster than light travel , Francis Litterio
<fr...@world.std.REMOVETHIS.com> wrote:
> Richard Caldwell <richard....@OSF25.oklaosf.state.ok.us> wrote:
>
> > > phenomonon such as wormholes are widely theorized by physicists as existing in
> > > a variety of forms, and it has been suggested that some such wormholes may
> > > even be traversable. By taking a shortcut through another dimention, it may
> > > be possible to circumvent the "speed of light" without ever violating
> > > relativity or making it invalid.
>
> > Agreed, and I sure hope you are right. Otherwise, we're stuck in a pretty small
> > neighborhood. 8-[
>
> It's a common misconception that the speed of light barrier prevents
> us from travelling great distances in short amounts of proper time.
Since I have a degree in Physics, I'm not subject to most of the "common
misconceptions" about STOR.
> With a sufficiently large expenditure of engery, rapid interstellar
> travel within one's lifetime is possible. If you travel fast enough,
> it is possible to get from Earth to Alpha Centauri (four light years
> distant) with only three months of food, water, and air on the ship.
> None of this contradicts Special Relativity. Just get ready to say
> goodbye to friends and familly forever (or take them with you).
Sure, the time compression effect of travelling at near c would make it hunkey dorey
for the people in the spaceship. However, as you point out, this time compression
effect does not apply to those left behind on Earth. This situation would make it
possible to explore the nearby stars (a "pretty small neighborhood"), but would render
regular transportation between the more distant stars *very* impractical.
Richard