Relative Speed of Observers --> Time Flow
Green Bishop
example to illustrate how observers moving relative to each other
observe the other's time flow. It is said that, given a fast-moving
observer, perhaps a person in an ultra-high-speed sports car which
approaches the realm of the speed of light, this observer will see a
stationary person's time to pass extremely slowly. However, the book
also tells me that the stationary observer will see the sports car and
its driver to have a slowed time flow. How is this possible? I thought
that as one approached the speed of light, one would experience time
slowed, not observe a slowed time flow in the rest of the universe.
How can both observers realize slowed time flow in the other? Please
clarify for young student interested in relativity.
Simon G Best
The first thing that I'd like to suggest (and which comes partly from
your subject line) is that you might be thinking of time itself flowing
with respect to ... ?
Consider the following: if time really did slow down for you, how would
you even experience that? After all, all your perceptions would be
slowed down, too, and your brain would we slowed down, and so on. So,
no matter how fast you're travelling, when you look at your watch (which
is moving with you), you'll always find that it's running at the right
speed. This is because either you and your watch have been slowed down,
or because neither you nor your watch have been slowed down.
But that's not really relativity. It's just to clarify what isn't meant
by time dilation (the phenomenon you're interested in).
Another idea to get clear about is that there's no such thing as
absolutely stationary. The "stationary" observer is only stationary
relative to that "stationary" observer. The person in the sports car is
similarly stationary relative to the sports car. The sports car is
travelling at high speed relative to the "stationary" observer, and the
"stationary" observer is travelling at high speed relative to the sports
car.
Time dilation is only part of the story. As well as the person in the
sports car observing the "stationary" observer's watch running slow, and
the "stationary" observer observing the person in the sports car's watch
running slow, each will observe the other to be contracted along the
direction of movement (movement being relative). Furthermore, two
events which are simultaneous for one of the observers won't (generally)
be simultaneous for the other (and, again, this works both ways round).
Put time dilation, length contraction and relativity of simultaneity
together, and all the apparent contradictions and paradoxes there all
nicely disappear (as if they're all cancelling each other out).
The FAQ for this newsgroup (which, I suspect, can be found somewhere in
the archives at http://www.faqs.org) will probably be of interest to
you, and will probably answer your questions better than I have here!
:-)
Simon
Dirk Van de moortel
"Green Bishop" <green_...@hotmail.com> wrote in message news:4ac05ed0.03072...@posting.google.com...
> In "Black Holes and Time Warps" by Kip Thorne, the author gives an
> example to illustrate how observers moving relative to each other
> observe the other's time flow. It is said that, given a fast-moving
> observer, perhaps a person in an ultra-high-speed sports car which
> approaches the realm of the speed of light, this observer will see a
> stationary person's time to pass extremely slowly. However, the book
> also tells me that the stationary observer will see the sports car and
> its driver to have a slowed time flow. How is this possible? I thought
> that as one approached the speed of light, one would experience time
> slowed, not observe a slowed time flow in the rest of the universe.
One experiences nothing. Every inertial observer feels nothing
and cannot tell that she is moving. Her time ticks quite normally
and she will notice nothing special about it. This is called her
"proper time".
> How can both observers realize slowed time flow in the other? Please
> clarify for young student interested in relativity.
When two inertial observers are moving with respect to each
other with constant velocity, neither one of them can find out
who is moving, at least not without looking outside. If they are
far away from masses, all they can do is look at each other
and send signals to each other. If for some reason A finds
that B's clock is somehow ticking slower than his, B will also
find that A's clock is ticking slower than hers.
You will find a decent and well written introduction on
http://phyun5.ucr.edu/~wudka/physics7.html
http://phyun5.ucr.edu/~wudka/Physics7/Notes_www/pdf_notes.html
Enjoy.
... and beware Usenet ;-)
Dirk Vdm
Hayek
Time flow is rubbish. There is no time flow.
There is inertial increase, and a clock is an
inertiameter. (and biochemical processes too)
That the rest of the universe's time slows down is
plain rubbish, due to a false interpretation of
the name "relativity".
You should never see "relativity" loose from the
gravitational background metric of the masses in
the universe.
Read this :
http://www.mathpages.com/home/albro/albro2.htm
"
I must say, this entire discussion has a strong
ironic element, because in the age-old debate
between absolute and relational theories of space,
time, and motion, the theory of relativity
represents the absolute side. It's well known
(outside of internet discussions) that the theory
of relativity is most definitely NOT a relational
theory of motion, i.e., it does not attribute all
physical effects to the relations between material
bodies.
The effects are ultimately determined by the
absolute background metric, which is affected by,
but is not determined by, the distribution of
material objects (except arguably in some specific
cosmological models that are not currently in
favor among cosmologists). Thus, relativity, no
less than Newtonian mechanics, relies on
space(time) as an absolute entity in itself,
exerting influence on material bodies. (This is
typically introduced to relativistic treatments by
a set of boundary conditions necessary to
determine a solution of the field equations.)
There actually have been attempts to create true
*relational* theories of motion, notably the
interesting work of Barbour and Bertotti in the
1970's. It's just an unfortunate historical
accident that the name "relativity" was given to
Einstein's theory. The word actually refers to
the covariance of spatial and temporal intervals,
not to any Leibnizian notion that only the
relations between material objects are
physically significant. Admittedly Einstein was
sympathetic to this philosophy, especially early
in his career, and entertained hopes of banishing
absolute space from physics, but like Newton
before him he was forced to abandon this hope in
order to produce a theory
that satisfactorily represents our observations.
It is therefore doubly ironic to see Einstein
daily excoriated in this newsgroup for foisting a
relational theory of motion on the world."
http://www.mathpages.com/rr/s4-07/4-07.htm
4.7 The Inertia of Twins
"
The puzzling asymmetry of the spinning globes is
essentially just another form of the twins
paradox, where the twins separate and reconverge
(one accelerates away and back while the other
remains stationary), and they end up with
asymmetric lapses of proper time. How can the
asymmetry be explained? According to Einstein:
"The only satisfactory answer must be that the
physical system consisting of S1 and S2 reveals
within itself no imaginable cause to which the
differing behavior of S1 and S2 can be referred.
The cause must therefore lie outside the system.
We have to take it that the general laws of
motion...must be such that the mechanical behavior
of S1 and S2 is partly conditioned, in quite
essential respects, by distant masses which we
have not included in the system under consideration."
"
http://www.mathpages.com/rr/s7-01/7-01.htm
7.1 Is the Universe Closed?
"
Nevertheless, the idea of a closed finite universe
is still of interest, partly because of the
historical role it played in Einstein's thought,
but also because it
remains (arguably) the model most compatible with
the spirit of general relativity. In an address to
the Berlin Academy of Sciences in 1921, Einstein
said :
"I must not fail to mention that a theoretical
argument can be adduced in favor of the hypothesis
of a finite universe. The general theory of
relativity teaches that the inertia of a given
body is greater as there are more ponderable
masses in proximity to it; thus it seems very
natural to reduce the total effect of inertia of a
body to action and reaction between it and the
other bodies in the universe... From the general
theory of relativity it can be deduced that this
total reduction of inertia
to reciprocal action between masses - as required
by E. Mach, for example - is possible only if the
universe is spatially finite. On many physicists
and astronomers
this argument makes no impression... "
"
http://www.mathpages.com/home/albro/albro16.htm
"
To put this in more familiar terms, Einstein would
say to all the people who claim that special
relativity is adequate to "handle" the twins
paradox: We can say that
the twin who followed the unaccelerated worldline
will have aged the most, but if we are asked which
twin had the unaccelerated worldline we can only
answer: the one
who aged the most! Accelerometers can't rescue us
from this circle, because the Equivalence
Principle implies that the lapse of proper time
along a given worldline
cannot be inferred from the locally "felt"
accelerations. For example, both twins could
spend the entire interval from A to B experiencing
1g of local
acceleration, and yet the lapses of proper time
could be vastly different.
Thus, as soon as the Equivalence Principle is
adopted, it's clear that special relativity is
epistemologically unsatisfactory, and can only be
salvaged by a suitable theory of gravitation
(e.g., general relativity), within which SR may
serve as a useful approximate simplification in
appropriate limiting cases. However,
we can only assess the appropiateness of SR in a
given circumstance by evaluating it in the context
of GR. In other words, SR can serve as a set of
convenient
computational recipes for technicians who don't
want or need to understand what they are doing,
but from an epistemological standpoint there is
only one modern
theory of relativity, and that is GENERAL
relativity. Special relativity had already been
discarded as a viable theory of knowledge by 1911.
I think it's also worth mentioning that when
ordinary non-physicists ask about relativity, they
aren't hoping to become technicians or
computational experts, they are asking from a
broad philosophical and epistemological
standpoint, i.e., they are curious to know, in
broad terms, the basis of relativity as a theory
of knowledge.
From this perspective, the custom of telling such
people that special relativity is "the answer" to
the twin's paradox is particularly unfortunate.
(I say this in spite of the undeniable fact that
most people who worry about the twins paradox have
actually failed to understand special relativity,
and aren't even close to the level of
comprehension on which the actual inadequacy of
special relativity appears. On the other hand,
most of the people who DON'T worry about the twins
paradox are equally far from understanding the
real issues involved.)
"
Hayek.
Dirk Van de moortel
"Dirk Van de moortel" <dirkvand...@ThankS-NO-SperM.hotmail.com> wrote in message
news:vXBTa.28762$F92....@afrodite.telenet-ops.be...
[snip]
> You will find a decent and well written introduction on
> http://phyun5.ucr.edu/~wudka/physics7.html
> http://phyun5.ucr.edu/~wudka/Physics7/Notes_www/pdf_notes.html
>
> Enjoy.
> ... and beware Usenet ;-)
... and frustrated individuals who point to www.mathpages.com .
Stay away from it during at least the first 5 years of your study.
If you go there now, you'll end up as frustrated as if you would
read Misner, Thorne and Wheeler's Gravitation at this stage :-)
Dirk Vdm
Hayek
Dirk Van de moortel wrote:
> "Dirk Van de moortel" <dirkvand...@ThankS-NO-SperM.hotmail.com> wrote in message
> news:vXBTa.28762$F92....@afrodite.telenet-ops.be...
>
> [snip]
>
>
>>You will find a decent and well written introduction on
>> http://phyun5.ucr.edu/~wudka/physics7.html
>> http://phyun5.ucr.edu/~wudka/Physics7/Notes_www/pdf_notes.html
>>
>>Enjoy.
>>... and beware Usenet ;-)
>
>
> ... and frustrated individuals who point to www.mathpages.com .
Like this one :
http://www.google.com/groups?selm=J%25Nz9.14833%24Nd.4010%40afrodite.telenet-ops.be&oe=UTF-8&output=gplain
Hayek.
Hayek
Dirk Van de moortel wrote:
>>... and beware Usenet ;-)
He knows his own act.
>
> ... and frustrated individuals who point to www.mathpages.com .
Hayek.
(replaces earlier cancelled message)
Dirk Van de moortel
"Hayek" <hay...@nospam.xs4all.nl> wrote in message news:3F1EF6FF...@nospam.xs4all.nl...
I was waiting for it :-)
Aren't we so predictable?
Dirk Vdm
Hayek
Dirk Van de moortel wrote:
> "Dirk Van de moortel" <dirkvand...@ThankS-NO-SperM.hotmail.com> wrote in message
> news:vXBTa.28762$F92....@afrodite.telenet-ops.be...
>
> [snip]
>
>
>>You will find a decent and well written introduction on
>> http://phyun5.ucr.edu/~wudka/physics7.html
>> http://phyun5.ucr.edu/~wudka/Physics7/Notes_www/pdf_notes.html
>>
>>Enjoy.
>>... and beware Usenet ;-)
>
>
> ... and frustrated individuals who point to www.mathpages.com .
> Stay away from it during at least the first 5 years of your study.
5 years ? You did 20 and still do not know what
you are talking about.
> If you go there now, you'll end up as frustrated as if you would
> read Misner, Thorne and Wheeler's Gravitation at this stage :-)
That would be : as Dirk reads the MTW and
concludes that if he does not understand, then
nobody will.
Hayek.
Martin Hogbin
"Simon G Best" <s.g....@btopenworld.com> wrote in message news:3F1EEE6E...@btopenworld.com...
.>
> The FAQ for this newsgroup (which, I suspect, can be found somewhere in
> the archives at http://www.faqs.org) will probably be of interest to
> you, and will probably answer your questions better than I have here!
The FAQ for this newsgroup is now part of the physics FAQ,
which can be found at:
http://www.physics.adelaide.edu.au/~dkoks/Faq/index.html
Martin Hogbin
Green Bishop
soon- I think I accidentally reposted when this first subject took a
very long time to come up. My apologies for the annoyancem and thanks
for the help. If anything, what's been said has only confused me more,
but that's all that this subject seems to bring up- more ideas leading
to more confusion. While I am nowhere near to understanding the
subject, at least I can have some idea about what I'm dealing with
Martin Hogbin
"Green Bishop" <green_...@hotmail.com> wrote in message news:4ac05ed0.03072...@posting.google.com...
Do not give up with this newsgroup, there are plenty of people
more than willing to help you understand the subject.
As you may have noticed, there are also many crackpots on
this group who post answers based on their own pet theories
rather than Einstein's theory of relativity, the only theory of
space and time accepted and used by physicists worldwide.
They are not too hard to spot, just ignore their replies.
So, what is it that is confusing you?
Martin Hogbin
alen
at the following link:
http://home.westserv.net.au/~alen1/Physics/index.htm
This solution doesn't rely on anything outside
special relativity itself, and allows the twins to be
perfectly identical in everything.
Alen
Green Bishop <green_...@hotmail.com> wrote in article
<4ac05ed0.03072...@posting.google.com>...
Dirk Van de moortel
"alen" <al...@westserv.net.au> wrote in message news:01c351ec$f5392300$437ea6cb@default...
> I have suggested a different solution to the twins paradox
> at the following link:
> http://home.westserv.net.au/~alen1/Physics/index.htm
>
> This solution doesn't rely on anything outside
> special relativity itself, and allows the twins to be
> perfectly identical in everything.
>
> Alen
Replacing your tau with t' and gamma with g, you write:
| To get the total time accumulated by the travelling clock, the
| Lorentz equation is used to integrate dt' in terms of dt as
|
| Int{ dt' } = Int{ (1/g) dt }
|
| and this is less than the accumulated time on the stationary clock,
| which is said to be simply Int{ dt } because, for the stationary
| clock, since its velocity in its own frame is zero,
|
| g = 1, and Int{ (1/g)dt } = Int{ dt }.
No problem, but then you go on:
| The problem with this is that the first of these equations cannot be
| integrated as it stands, in the accelerated case, because dt does not
| remain a constant interval. dt is a function of velocity in the
| Lorentz differential equation since dt' is, by definition, an invariant,
| and independent of velocity, and g is not. Since acceleration can be
| regarded as a stepwise series of inertial reference frames, each at
| a slightly different velocity, and, since the integral is equivalent
| to a summation of the times for which each of these lasts, the values
| of dt change incrementally with velocity.
This seems not right.
Of course dt and g are not invariants, but that is no reason why
the integral
Int{ (1/g) dt }
would not be an invariant.
The fact that it is equal to Int{ dt' } clearly shows that it is
an invariant.
The integral Int{ (1/g) dt } is to be taken over the worldline
of the clock. As soon as you have a description of the worldline
in *any* frame (using for example coordinates x and t), the
line integral can directly be calculated because
v(t) = dx/dt
and
g(t) = 1/sqrt[1-v(t)^2/c^2].
So you get
Int{ dt' } = Int{ t1 to t2; 1/g dt }
= Int{ t1 to t2; sqrt(1-v(t)^2/c^2) dt }
There is a well known calculus theorem that says that the
value of a line integral is independent of the parameterization.
And the parameterization we have here is as good as any
other, so the integral is ready to be calculated.
To take the example of an object that feels a constant proper
acceleration a, where the velocity v(t) = dx/dt of the object as
seen by the original frame is given by
v(t) = a*t / sqrt[1+(a*t/c)^2]
you get
Int{ dt' } = Int{ 0 to T; 1/g dt }
= Int{ 0 to T; sqrt(1-v(t)^2/c^2) dt }
= Int{ 0 to T; sqrt(1- [ a*t / sqrt[1+(a*t/c)^2] ]^2 /c^2) dt }
= Int{ 0 to T; sqrt[1/(1+(a*t/c)^2] dt }
to be solved numerically.
To take the example of the twins: the stay at home twin uses time t
and the travelling twin uses tau (t').
Suppose infinite acceleration from 0 to v and infinite deceleration
from v to -v. Suppose the stay at home twin measures his sister to
move away between t=0 and t=T/2, and to move back between
t=T/2 and t=T. The total time would then be T.
The velocities are given by
v(t) = v for 0 =< t =< T/2
v(t) = -v for T/2 < t =< T
So the total proper time can be easily calculated as follows:
Int{ dt' } = Int{ 1/g dt }
= Int{ 0 to T/2; 1/g dt } + Int{ T/2 to t1; 1/g dt }
= 1/g * Int{ 0 to T/2; dt } + 1/g * Int{ T/2 to t1; dt }
= 1/g * T/2 + 1/g * T/2
= T/g
So you immediately have the well known result
T' = Int{ dt' } = T/g < T.
Dirk Vdm
Jon Hurwitz
> If anything, what's been said has only confused me more,
> but that's all that this subject seems to bring up- more ideas leading
> to more confusion. While I am nowhere near to understanding the
> subject, at least I can have some idea about what I'm dealing with
This time last year I made a first concerted effort to get to grips with
relativity, and there were plenty of people in the group who helped a lot.
Unfortunately that didn't stop it taking a couple of months of hard thought
before even the basics started to click into place.
To understand why time is said to slow down, it's worth remembering that
physics is all about modelling the physical aspects of the universe. (I
simplify because I'm not a physicist, and I assume you aren't either, so
clarity over precision, okay.) With our model we can interpret measurements
to understand what has happened (bright new star in the sky- that'll be a
supernova), and we can predict what we think will happen in the future (I
drop the pen - it will fall). In special relativity (SR), all these
measurements take place against a backdrop of time and space.
We define our background of space and time however we choose and we end up
with what is called a frame. Then we stick some coordinates against our
frame so we can think about it more easily. "Normally" that's three
distance coordinates all at right angles to each other and one time
coordinate. In SR we assume that the frame is not being accelerated, what
is called an inertial frame.
The first thing that needs to be grasped is that we can chose our spacetime
background arbitrarily. I can centre it on me, orient it using Orion, pick
the date of my birth as time zero and make all my measurements accordingly.
You can centre it on you, orient it using the pole star, pick your mother's
fifth birthday as your time zero and make your measurements accordingly.
The principle of relativity says that the rules of physics will work just as
well for both of us. Of course the numbers we come up with will differ.
The time we predict something will happen can't be the same if we have
different time zero on our calendars, but in our own frames according to our
own schema we can make our separate predictions and we will agree: the pen
will hit the floor. We will be able to say when in our own measuring
systems, and we will both be right.
Even though we both have different numbers, asking who has the "right"
numbers is pointless. It's a bit like asking which is right, Centigrade or
Fahrenheit. This includes measurements of speed. Of course if my frame is
centred on me I am not moving. In fact I am always at (0, 0, 0) spatially
and I "travel" at zero speed. But you would disagree if we are moving
relative to each other. You have picked your frame to be centred on you and
according to your measurements it is you who are not moving, but I am. Just
remember though that both our measurement systems work equally well, so it
is futile to ask who is *really* moving.
Of course it is possible to convert between the systems. We can subtract
our start dates, allow for orientation and origin. When we do, our
predictions can be shown to match.
Nearly there now.
According to SR, two different observers moving relative to each other do
not measure time as progressing at the same rate. Time moves at different
rates in different frames that move relative to each other.
In order for us to reconcile the time rates, we must make allowances and we
find that we have to assume that time slows down for the other frame. We
can't just subtract start times. Even if we choose the same start time,
things will get out of synch. We must allow for different time rates. And
we each must allow for a slower rate in the other frame.
This does not mean that you or I experience time differently just because
someone or something else is moving past us. How could it? There are
galaxies flying away from us at near lightspeed. In their frame it is we
who are travelling at near lightspeed, and I don't feel any different
because of it. Do you? It means that to reconcile the way we measure
things we must make these allowances. So it does affect what we measure.
It does mean that light getting to us (hence what we see) will be affected.
If you travel toward me at three quarters of light speed flashing a beacon
once a second (as you measure it), I will see it, after allowing for Doppler
shift, every one and a half seconds.
And if I flash my beacon at you once a second (as I measure it), you will
see exactly the same slowdown.
Because we define our understanding of what space and time mean to us using
our frames, this slowdown is real. For example, the faster we measure a
sub-atomic particle to go, the longer we measure its half life to be. But
it is an effect of what we measure in others, rather than something
intrinsic in ourselves. We can both measure time going slower in the
other's frame because we all have our own systems of measurement.
It is the fact that different observers carry their own view of time with
them that is so very difficult to grasp. So many of our expectations, even
languages, are based on the idea that there is a real consistent universal
time, and that there is a real something called now. We believe that if you
run slower than me I must run faster than you, but it doesn't work like
that. We each carry our own independent time and you can measure me running
slower than you while I measure you running slower than me. Weird, but
that's what the theory predicts. And the universe seems to back it up!
Cheers,
Jon
alen
> Of course dt and g are not invariants, but that is no reason why
> the integral
> Int{ (1/g) dt }
> would not be an invariant
The integral is an invariant across all frames. I made a point only of the
fact that dt is not a constant interval, and this interferes with normal
integration.
> ... the
> value of a line integral is independent of the parameterization.
If I want to integrate f(x)dx, and dx is very small, changing the value of
dx may not
materially affect the result, if it remains independent of x.
But if dx is a function of x, that cannot be assumed to apply, and
normal integrals cannot be relied on.
> ...the stay at home twin uses time t
> and the travelling twin uses tau (t').
What I argued about this was that t is a future time on the stay at home
twin's clock, and not his current, or visible, or proper time, and the
summation
of dt, greater than dtau, will not be the summation visible when the
travelling
twin returns, but will occur only in the future.
Alen
Dirk Van de moortel
"alen" <al...@westserv.net.au> wrote in message news:01c352b2$f9afa500$0b7ea6cb@default...
> Dirk
>
> > Of course dt and g are not invariants, but that is no reason why
> > the integral
> > Int{ (1/g) dt }
> > would not be an invariant
>
> The integral is an invariant across all frames. I made a point only of the
> fact that dt is not a constant interval, and this interferes with normal
> integration.
It most certainly does not.
>
> > ... the
> > value of a line integral is independent of the parameterization.
>
> If I want to integrate f(x)dx, and dx is very small, changing the value of
> dx may not
> materially affect the result, if it remains independent of x.
> But if dx is a function of x, that cannot be assumed to apply, and
> normal integrals cannot be relied on.
You seem to have no idea about elementary calculus.
Have you ever even *looked* at how Int{ f(x)dx } is
defined?
>
> > ...the stay at home twin uses time t
> > and the travelling twin uses tau (t').
>
> What I argued about this was that t is a future time on the stay at home
> twin's clock, and not his current, or visible, or proper time, and the
> summation
> of dt, greater than dtau, will not be the summation visible when the
> travelling
> twin returns, but will occur only in the future.
All this sounds like complete rubbish.
Dirk Vdm
alen
> Have you ever even *looked* at how Int{ f(x)dx } is
> defined?
Can you, for example, convert Int{x^2dx} to Int{xdx'}, where dx' = xdx
and use normal integration on the converted integral?
Alen
Dirk Van de moortel
"alen" <al...@westserv.net.au> wrote in message news:01c3533f$435e3b80$297ea6cb@default...
> > You seem to have no idea about elementary calculus.
> > Have you ever even *looked* at how Int{ f(x)dx } is
> > defined?
Did you ever follow a proper calculus course?
> Can you, for example, convert Int{x^2dx} to Int{xdx'}, where dx' = xdx
> and use normal integration on the converted integral?
There is no such thing as a 'converted integral'.
An integral is an integral. Period.
The integral
Int{ t1 to t2; 1/g dt }
can be immediately and straightforwardly calculated when
you know g as a function of t.
I gave two perfectly valid examples. Tear them apart if you
can.
Dirk Vdm
alen
I am not satisfied with that.
If you have simply Int{1/gdt}, where dt
can have an arbitrary value, I agree
that there is no problem.
But if you have dt' = 1/gdt, and then fix
the value of dt' as an invariant, dt cannot
be arbitrary, but becomes a kind of
function corresponding to g.
I think that that is significant.
Alen
Dirk Van de moortel
"alen" <al...@westserv.net.au> wrote in message news:01c35389$469990c0$547ea6cb@default...
> > An integral is an integral. Period.
>
> I am not satisfied with that.
>
> If you have simply Int{1/gdt}, where dt
> can have an arbitrary value, I agree
> that there is no problem.
Well, *I* would not agree at all, because the phrase
"dt can have an arbitrary value" is utterly meaningless.
>
> But if you have dt' = 1/gdt, and then fix
> the value of dt' as an invariant, dt cannot
> be arbitrary, but becomes a kind of
> function corresponding to g.
>
> I think that that is significant.
I know by now that you think it is significant.
Go for a good calculus course. Unless you do, I'm afraid
there is no way you will be able to communicate about this
with anyone.
But looking at the effort you have put in those webpages
of yours, I suspect you might not be inclined to give it up.
That's your problem of course. You are the one who can
do something about it.
Hint: in stead of stating 'facts' and telling that everyone
has been wrong all the time, try saying that you have a
problem, and ask questions.
Dirk Vdm
Hayek
Since only DVdm and I answered I take it you
target me as a crackpot. I find that odd since I
illustrated my point of view with quotes from
Einstein himself, as you can read in my post.
So, if you talk about "Einstein's theory of
relativity, the only theory of space and time
accepted and used by physicists worldwide" , are
you sure what the theory is about and what is
accepted and what not ?
Hayek.
John Anderson
Green Bishop wrote:
You should look in the FAQ for this newsgroup.
Briefly, when to two observers compare their clocks
and they are spatially separated, they disagree about
which events are simultaneous (predicted by SR).
Therefore, they compare clock readings at different
events and this leads to each one believing that
the other's clock runs slower than his/her own.
John Anderson
alen
> there is no way you will be able to communicate about this
> with anyone.
> But looking at the effort you have put in those webpages
> of yours, I suspect you might not be inclined to give it up.
> That's your problem of course. You are the one who can
> do something about it.
> Hint: in stead of stating 'facts' and telling that everyone
> has been wrong all the time, try saying that you have a
> problem, and ask questions.
You, and not I, are the one saying that I have a problem.
That means to me only that you don't agree with me, and
not automatically that what I am saying is meaningless.
Therefore I respond by saying merely that we disagree, and
you are entitled to your view.
Alen
Dirk Van de moortel
"alen" <al...@westserv.net.au> wrote in message news:01c353f4$853d0440$4d7ea6cb@default...
Okay, I'll try to sketch the generally accepted view so you
can show what is wrong with it.
An observer uses coordinates x, y, z and t to describe a clock
that is moving in spacetime and that ticks away time t' (tau).
The observer notices that the motion of the clock can be
described with 3 functions:
x(t), y(t) and z(t)
He decides to concentrate on what happens between two
events: one event E1 where his own clock says t=t1 and
the moving clock says t' = t'1, and another event E2 where
his own clock says t=t2 and the moving clock says t' = t'2.
Using standard calculus he can calculate the functions
dx/dt, dy/dt and dz/dt
Using standard calculus he can calculate the function
v(t) = sqrt[ (dx/dt)^2 + (dy/dt)^2 + (dz/dt)^2 ]
Using standard calculus he can calculate the function
g(t) = 1 / sqrt[ 1 - v(t)^2/c^2 ]
Using standard calculus he can calculate the integral
Int{ t1 to t2; 1/g(t) dt }
According to relativity theory the value of this integral is
invariant, i.e. it is the same for every inertial observer who
measures coordinate functions to describe the motion of
the clock, and calculates the integral. This includes the
observer who is sitting *on* the clock itself, and for whom
the functions are zero and therefore g = 1, i.o.w. the value
of the integral is
Int{ t'1 to t'2; dt' } = t'2 - t'1
Since all these integrals have the same value for every
observer, it made sense to give it a name, and the name
has been chosen to be: "the proper time of the clock
between the events E1 and E2".
Now what exactly is wrong and why?
Dirk Vdm
alen
> events: one event E1 where his own clock says t=t1 and
> the moving clock says t' = t'1, and another event E2 where
> his own clock says t=t2 and the moving clock says t' = t'2.
I say that this standard view about what each clock 'says', ie
at present, is an unjustified assumption. We have a valid relationship
of clock times, yes, but to assume that, in the equations, they are
always 'present' times, excluding the past and future,
assumes what has not been established.
> Using standard calculus he can calculate the integral
> Int{ t1 to t2; 1/g(t) dt }
Despite the fact that this is written as a perfectly ordinary
integral, I have disputed that it really is so, as you know.
If I want to calculate S{dt'} = S{1/g(t)dt}, (S for summation),
specifying always dt'=1/gdt, and then take dt infinitesimally small,
I should let dt' always be a resultant value and not fix it
as a constant in advance. But dt' is specified in advance
as an invariant, independent of g.
I am quite happy to acknowledge your right, if you feel it
necessary to adopt the view that this is all nonsense.
Alen
Dirk Van de moortel
"alen" <al...@westserv.net.au> wrote in message news:01c3544a$16fb8000$427ea6cb@default...
> > He decides to concentrate on what happens between two
> > events: one event E1 where his own clock says t=t1 and
> > the moving clock says t' = t'1, and another event E2 where
> > his own clock says t=t2 and the moving clock says t' = t'2.
>
> I say that this standard view about what each clock 'says', ie
> at present, is an unjustified assumption.
I knew you would run away at this early stage, even *before*
we get to the elementary calculus part.
I just did some research and found that you seem to be in the
process of developping a habit of saying something silly and
then run away with your fingers in your ears:
http://superstringtheory.com/forum/relboard/messages18/9.html
culminating in
http://superstringtheory.com/forum/relboard/messages18/62.html
"Yes, I'm not listening because I don't agree"
If you want to be treated like an idiot or like a troll, do continue
to act like one.
Dirk Vdm
Ken S. Tucker
To Alen,
regrets that you had to meet Dirk, he is NOT
characteristic of our NG. It's quite evident he is infatuated
with his own intelligence, and even more so with any tiny
ignorance within anyone else. His manuever to find some
invention to refer to you as an "idiot and a troll" proves
my point, and having reviewed this thread, and anyone
else can verify your sustained verbal objectiveness inspite
of Dirks evident wisecracks.
I mention this because Dirks a bit like the local watch
dog, he barks, but don't take it too serious, and so I hope
this thread settles down so the more educated of the group
may respond to the issue you have presented.
Regards as usual to Dirk and to Alen
Ken S. Tucker
Hayek
Dirk Van de moortel wrote:
> "Yes, I'm not listening because I don't agree"
That would be perfect as your sig.
When was the last time you listened, or agreed on
something ?
Hayek.
Dirk Van de moortel
"Hayek" <hay...@nospam.xs4all.nl> wrote in message news:3F242474...@nospam.xs4all.nl...
He inertia idiot, this was a quote from "alen":
http://superstringtheory.com/forum/relboard/messages18/62.html
>
>
> Hayek.
>
>
Dirk Van de moortel
"Ken S. Tucker" <dyna...@vianet.on.ca> wrote in message news:2202379a.03072...@posting.google.com...
Fantastic, just what we needed: regards from
Ken Temperature Vector Tucker:
http://groups.google.com/groups?&threadm=I11Na.5108$7h....@afrodite.telenet-ops.be
Dirk Vdm
alen
more than simply that you don't agree
with me.
Is it the case that in Physics, unlike in some other
spheres of discussion, people don't know how
to acknowledge that independent individuals
can have independent viewpoints?
Alen
alen
I appreciate your post.
Since I am here I will mention that I have
just changed the website text dealing with
integration, that Dirk made such a point of.
The original remarks were somewhat careless
and incomplete, since I was more interested
in the argument about SR.
However, I don't expect this to make any
difference to Dirk, since the underlying
argument remains the same.
Alen.
Dirk Van de moortel
"alen" <al...@westserv.net.au> wrote in message news:01c354d2$ef8d8340$0b7ea6cb@default...
> The sum total of your remarks is nothing
> more than simply that you don't agree
> with me.
Yes, I know you claim to think that is a question of
agreement.
>
> Is it the case that in Physics, unlike in some other
> spheres of discussion, people don't know how
> to acknowledge that independent individuals
> can have independent viewpoints?
There is no reason to be afraid :-)
You are entitled to have any viewpoint you like.
You can tell the silliest things about any subject you want.
You can ignore anything anyone cares to offer to help.
You can go to a physics group and say that all physicists
have been wrong all the time.
You can say "This solution doesn't rely on anything
outside special relativity itself" and show that you haven't
understood the first letter of relativity to begin with.
When you are told what the definitions of the theory are
and how events are used in the theory, you can brush
everything aside with a fantastic remark "I say that this
standard view about what each clock 'says', ie at present,
is an unjustified assumption."
You can talk about integrals and use phrases like
"converted integrals" and
"normal integration" and
"dt changes incrementally with velocity" and
"t is a future time of a clock" and
"fixing dt' as an invariant" and
"dx depending on x" and
"dt having an arbitrary value" and
"becoming a kind of function" and
"taking dt infinitesimally small"
and show that you haven't understood the first letter
about calculus either.
You can ignore all the detailed examples that prove you wrong.
You can say "I don't listen because I don't agree".
You can do all that.
You will even get support (well, erm, support... sort of) from
hayeks ("AIDS is not caused by HIV") and kentuckers.
Isn't Usenet a fantastic place?
Dirk Vdm
Hayek
alen wrote:
> Ken
>
> I appreciate your post.
>
> Since I am here I will mention that I have
> just changed the website text dealing with
> integration, that Dirk made such a point of.
> The original remarks were somewhat careless
> and incomplete, since I was more interested
> in the argument about SR.
I repeat these texts again with an emphasis on
this excerpt :
"
...In other words, SR can serve as a set of
convenient computational recipes for technicians
who don't want or need to understand what they are
doing, but from an epistemological standpoint
there is only one modern theory of relativity, and
that is GENERAL relativity. Special relativity had
already been discarded as a viable theory of
knowledge by 1911....
"
http://www.mathpages.com/home/albro/albro2.htm
"
I must say, this entire discussion has a strong
ironic element, because in the age-old debate
between absolute and relational theories of space,
time, and motion, the theory of relativity
represents the absolute side. It's well known
(outside of internet discussions) that the theory
of relativity is most definitely NOT a relational
theory of motion, i.e., it does not attribute all
physical effects to the relations between material
bodies.
The effects are ultimately determined by the
absolute background metric, which is affected by,
but is not determined by, the distribution of
material objects (except arguably in some specific
cosmological models that are not currently in
favor among cosmologists). Thus, relativity, no
less than Newtonian mechanics, relies on
space(time) as an absolute entity in itself,
exerting influence on material bodies. (This is
typically introduced to relativistic treatments by
a set of boundary conditions necessary to
determine a solution of the field equations.)
There actually have been attempts to create true
*relational* theories of motion, notably the
interesting work of Barbour and Bertotti in the
1970's. It's just an unfortunate historical
accident that the name "relativity" was given to
Einstein's theory. The word actually refers to
the covariance of spatial and temporal intervals,
not to any Leibnizian notion that only the
relations between material objects are
physically significant. Admittedly Einstein was
sympathetic to this philosophy, especially early
in his career, and entertained hopes of banishing
absolute space from physics, but like Newton
before him he was forced to abandon this hope in
order to produce a theory
that satisfactorily represents our observations.
It is therefore doubly ironic to see Einstein
daily excoriated in this newsgroup for foisting a
relational theory of motion on the world."
http://www.mathpages.com/rr/s4-07/4-07.htm
4.7 The Inertia of Twins
"
The puzzling asymmetry of the spinning globes is
essentially just another form of the twins
paradox, where the twins separate and reconverge
(one accelerates away and back while the other
remains stationary), and they end up with
asymmetric lapses of proper time. How can the
asymmetry be explained? According to Einstein:
"The only satisfactory answer must be that the
physical system consisting of S1 and S2 reveals
within itself no imaginable cause to which the
differing behavior of S1 and S2 can be referred.
The cause must therefore lie outside the system.
We have to take it that the general laws of
motion...must be such that the mechanical behavior
of S1 and S2 is partly conditioned, in quite
essential respects, by distant masses which we
have not included in the system under consideration."
"
http://www.mathpages.com/rr/s7-01/7-01.htm
7.1 Is the Universe Closed?
"
Nevertheless, the idea of a closed finite universe
is still of interest, partly because of the
historical role it played in Einstein's thought,
but also because it remains (arguably) the model
most compatible with the spirit of general
relativity. In an address to the Berlin Academy of
Sciences in 1921, Einstein said :
"I must not fail to mention that a theoretical
argument can be adduced in favor of the hypothesis
of a finite universe. The general theory of
relativity teaches that the inertia of a given
body is greater as there are more ponderable
masses in proximity to it; thus it seems very
natural to reduce the total effect of inertia of a
body to action and reaction between it and the
other bodies in the universe... From the general
theory of relativity it can be deduced that this
total reduction of inertia to reciprocal action
between masses - as required by E. Mach, for
example - is possible only if the universe is
spatially finite. On many physicists and
astronomers this argument makes no impression... "
"
http://www.mathpages.com/home/albro/albro16.htm
"
To put this in more familiar terms, Einstein would
say to all the people who claim that special
relativity is adequate to "handle" the twins
paradox: We can say that the twin who followed
the unaccelerated worldline will have aged the
most, but if we are asked which twin had the
unaccelerated worldline we can only answer: the
one who aged the most! Accelerometers can't
rescue us from this circle, because the
Equivalence Principle implies that the lapse of
proper time along a given worldline cannot be
inferred from the locally "felt" accelerations.
For example, both twins could spend the entire
interval from A to B experiencing 1g of local
acceleration, and yet the lapses of proper time
could be vastly different.
Thus, as soon as the Equivalence Principle is
adopted, it's clear that special relativity is
epistemologically unsatisfactory, and can only be
salvaged by a suitable theory of gravitation
(e.g., general relativity), within which SR may
serve as a useful approximate simplification in
appropriate limiting cases. However, we can only
assess the appropiateness of SR in a given
circumstance by evaluating it in the context of
GR. In other words, SR can serve as a set of
convenient computational recipes for technicians
who don't want or need to understand what they are
doing, but from an epistemological standpoint
there is only one modern theory of relativity, and
that is GENERAL relativity. Special relativity had
already been discarded as a viable theory of
knowledge by 1911. I think it's also worth
mentioning that when ordinary non-physicists ask
about relativity, they aren't hoping to become
technicians or computational experts, they are
asking from a broad philosophical and
epistemological standpoint, i.e.,
they are curious to know, in broad terms, the
basis of relativity as a theory of knowledge.
From this perspective, the custom of telling such
people that special relativity is "the answer" to
the twin's paradox is particularly unfortunate.
(I say this in spite of the undeniable fact that
most people who worry about the twins paradox have
actually failed to understand special relativity,
and aren't even close to the level of
comprehension on which the actual inadequacy of
special relativity appears. On the other hand,
most of the people who DON'T worry about the twins
paradox are equally far from understanding the
real issues involved.)
"
Dirk Van de moortel
"alen" <al...@westserv.net.au> wrote in message news:01c3551d$49932b20$357ea6cb@default...
Well... I must admit, I had a look at it, and apparently
you managed to make it even worse. Good job :-)
Dirk Vdm
Ken S. Tucker
>"Ken S. Tucker" <dyna...@vianet.on.ca> wrote in message news:2202379a.03072...@posting.google.com...
>> "Dirk Van de moortel" <dirkvand...@ThankS-NO-SperM.hotmail.com> wrote in message news:<xtRUa.35846$F92....@afrodite.telenet-ops.be>...
[snip]
>> I mention this because Dirks a bit like the local watch
>> dog, he barks, but don't take it too serious, and so I hope
>> this thread settles down so the more educated of the group
>> may respond to the issue you have presented.
>> Regards as usual to Dirk and to Alen
>
>Fantastic, just what we needed: regards from
>Ken Temperature Vector Tucker:
> http://groups.google.com/groups?&threadm=I11Na.5108$7h....@afrodite.telenet-ops.be
>Dirk Vdm
Dirk, Thank you for the praise.
In the post you cited, it was clear from the presented context,
that temperature, examined microscopically, is indeed a vectorial
quantity, and depends on the masses of the particles and their
relative motion, ultimately w.r.t the observer. A case in point,
a shuttle re-entering Earth's atmosphere measures a very high
temperature of the atmosphere, but a balloon at that same
altitude might measure freezing temperatures. Naturally this
temperature difference is accountable by differing speeds of
the reference frame holding the thermometer.
The presumption that temperature is a scalar is based
on obsolete conditions, and your rush to find fault in my
view, by embracing these obsolete conditions, indicates
a desire to find fault at the expense of thought.
Given your evident proclivity to find and archive stupid
postings, I will provide freely my posting....
Subject: Inflationary Red Shift Explanation?
In which I make a complete fool of myself, and working
to retract. And with regards, I will keep you informed of
my stupidity as it arises, if you're ok working over-time.
Regards
Ken S. Tucker
Dirk Van de moortel
"Ken S. Tucker" <dyna...@vianet.on.ca> wrote in message news:2202379a.0307...@posting.google.com...
> "Dirk Van de moortel" <dirkvand...@ThankS-NO-SperM.hotmail.com> wrote in message
news:<KxXUa.36435$F92....@afrodite.telenet-ops.be>...
>
> >"Ken S. Tucker" <dyna...@vianet.on.ca> wrote in message news:2202379a.03072...@posting.google.com...
> >> "Dirk Van de moortel" <dirkvand...@ThankS-NO-SperM.hotmail.com> wrote in message
news:<xtRUa.35846$F92....@afrodite.telenet-ops.be>...
> [snip]
> >> I mention this because Dirks a bit like the local watch
> >> dog, he barks, but don't take it too serious, and so I hope
> >> this thread settles down so the more educated of the group
> >> may respond to the issue you have presented.
> >> Regards as usual to Dirk and to Alen
> >
> >Fantastic, just what we needed: regards from
> >Ken Temperature Vector Tucker:
> > http://groups.google.com/groups?&threadm=I11Na.5108$7h....@afrodite.telenet-ops.be
> >Dirk Vdm
>
> Dirk, Thank you for the praise.
> In the post you cited, it was clear from the presented context,
> that temperature, examined microscopically, is indeed a vectorial
> relative motion, ultimately w.r.t the observer.
This deserves the prize for the lamest excuse of the century :-)))
Brilliant!
Too bad you agreed in your reply:
|
| >I certainly did not suggest, nor can I possibly imagine
| >that temperature could have a direction. But YMMV.
| >Dirk Vdm
|
| Agreed, fluid flow would have been a better interpretation,
| on my part.
|
Really brilliant, don't you agree, "alen"?
Dirk Vdm
Hayek
Dirk Van de moortel wrote:
> You will even get support (well, erm, support... sort of) from
> hayeks ("AIDS is not caused by HIV") and kentuckers.
> Isn't Usenet a fantastic place?
Well, I got news for you.
A new discovery was made earlier this year,
concerning cellular biology.
Earlier it was assumed that dna was the
orchestrator of everything that happened in the
cell. This turned out to be different. Now, it is
assumed that cell rna orchestrates everything, and
that it merely uses dna as a sort of library. This
means that reverse transcribing is common in human
cell biodynamics, and that the whole retroviral
theory was at fault to begin with. By the end of
the year more results will be in and the picture
will be clearer.
Two more epicycles : 9% of new aids-cases in
Western Europe seem to be resistent to medication.
For the Netherlands that means 4 cases and for
Belgium 10. (45 new cases in 2001, resp. 110 new
cases in 2001).
And AIDS translates now in strokes, heart attacks
and liver failure. Immune deficiency ? Sounds more
like medication deficiency.
And to come back to our different views on
relativity :
You are satisfied when you can calculate and
predict results for devices or experiments. That
is fine, but it does not give you the right to
scorn people that want to know how and why
relativity (and qm) works. The "why" does not
intrest you, and that is your privilege, and it is
mine and other's here to be intrested in the
"why". You do not have any answers in this realm,
or even have a clue and you try to hide this by
insulting everybody that asks "why".
http://www.mathpages.com/rr/s4-01/4-01.htm
4.1 Immovable Spacetime
"
However, it remains possible to regard fields
as only representations of effects, and to insist
on materiality for ontological objects, in which
case the absolute-relational question remains both
relevant and unresolved.
"
Hayek.
Dirk Van de moortel
"Hayek" <hay...@nospam.xs4all.nl> wrote in message news:3F2596F...@nospam.xs4all.nl...
>
>
> Dirk Van de moortel wrote:
>
> > You will even get support (well, erm, support... sort of) from
> > hayeks ("AIDS is not caused by HIV") and kentuckers.
> > Isn't Usenet a fantastic place?
>
> Well, I got news for you.
You always have news. Good for you.
Dirk Vdm
shuba
> You can talk about integrals and use phrases like
> "converted integrals" and
> "normal integration" and
> "dt changes incrementally with velocity" and
> "t is a future time of a clock" and
> "fixing dt' as an invariant" and
> "dx depending on x" and
> "dt having an arbitrary value" and
> "becoming a kind of function" and
> "taking dt infinitesimally small"
> and show that you haven't understood the first letter
> about calculus either.
I've always been under the impression that "dummy" is supposed to
refer to a variable, not the person with a pencil.
---Tim Shuba---
Hayek
Dirk Van de moortel wrote:
> "Hayek" <hay...@nospam.xs4all.nl> wrote in message news:3F2596F...@nospam.xs4all.nl...
>
>>
>>Dirk Van de moortel wrote:
>>
>>
>>>You will even get support (well, erm, support... sort of) from
>>>hayeks ("AIDS is not caused by HIV") and kentuckers.
>>>Isn't Usenet a fantastic place?
>>
>>Well, I got news for you.
>
>
> You always have news. Good for you.
Another fine case of Dirk's motto :
"Yes, I'm not listening because I don't agree"
It really fits you like a glove.
Hayek.
Dirk Van de moortel
"shuba" <tim....@eudoramail.com> wrote in message news:tim.shuba-E4A12...@corp.supernews.com...
:-)
Dirk Vdm