Solar Sails
Charles Allen
the following violated some laws of physics.
You have some space ship.
The ship has reflecting solar sails attached to the front of the ship.
Somewhere behind the ship there exists an electro-magnetic or gravitational
field of sufficient magnitude to cause a photon to "slingshot" back towards
the front of the ship.
The re-directed photon would reflect off the front sail, slingshot a second
time, reflect of the other side, and so on.
First question: Can anyone think of a way that wolud allow the use of
electrons instead of photons?
Second question: Where would the energy to propel the ship come from, if
this is even a plausable event?
Thanks,
Chuck
Mathew Orman
"Charles Allen" <cra...@purdue.edu> wrote in message
news:b1sdem$m0d$3...@mozo.cc.purdue.edu...
Light travel in straight lines only.
Mathew Orman
Bruce
"Mathew Orman" <or...@nospam.com> wrote:
>Light travel in straight lines only.
Really? Then Einstein was wrong.
Spaceman
"Bruce" <nu...@damn.business.com> wrote in message news:3e41c112...@news.houston.sbcglobal.net...
YUP!
on some stuff.
Mathew Orman
He was able to convince relevant people that he was right using his modified
version of mathematics.
Learn on!
Mathew Orman
Charles Allen
>
> Light travel in straight lines only.
So is gravitational lensing a myth?
Spaceman
"Charles Allen" <cra...@purdue.edu> wrote in message news:b1sgom$nhp$2...@mozo.cc.purdue.edu...
>
> >
> > Light travel in straight lines only.
>
>
> So is gravitational lensing a myth?
Partly the way the "time travel dupes and SR Queens and Kings describe it."
It is a real effect of light being "refracted"
but lights propagation path from refraction point to point is always
in a straight line.
It can not take a corner without a driver.
it needs to "reflect or refract" (bounce or be directed differently)
Uncle Al
A closed system cannot propel anything. Momentum is conserved, so is
energy.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!
Gregory L. Hansen
Charles Allen <cra...@purdue.edu> wrote:
>I was discussing solar sailors with a friend of mine and was wondering if
>the following violated some laws of physics.
>
>You have some space ship.
>The ship has reflecting solar sails attached to the front of the ship.
>Somewhere behind the ship there exists an electro-magnetic or gravitational
>field of sufficient magnitude to cause a photon to "slingshot" back towards
>the front of the ship.
>The re-directed photon would reflect off the front sail, slingshot a second
>time, reflect of the other side, and so on.
>
>First question: Can anyone think of a way that wolud allow the use of
>electrons instead of photons?
Magnetic dipole. The electrons would follow the field lines and bounce
away from the regions of higher intensity.
>
>Second question: Where would the energy to propel the ship come from, if
>this is even a plausable event?
You would get thrust only from the stuff that escapes to infinity. You
can't lift yourself into the air by pulling up on your own shoelaces (at
least I've never been able to), and you won't get thrust by bouncing
photons or electrons back and forth.
--
"A nice adaptation of conditions will make almost any hypothesis agree
with the phenomena. This will please the imagination but does not advance
our knowledge." -- J. Black, 1803.
Charles Allen
>> >
>> > Light travel in straight lines only.
>>
>>
>> So is gravitational lensing a myth?
>
> but lights propagation path from refraction point to point is always
> in a straight line.
Charles Allen
>>I was discussing solar sailors with a friend of mine and was wondering if
>>the following violated some laws of physics.
>>
>>You have some space ship.
>>The ship has reflecting solar sails attached to the front of the ship.
>>Somewhere behind the ship there exists an electro-magnetic or
>>gravitational field of sufficient magnitude to cause a photon to
>>"slingshot" back towards the front of the ship.
>>The re-directed photon would reflect off the front sail, slingshot a
>>second time, reflect of the other side, and so on.
>>
>>Second question: Where would the energy to propel the ship come from, if
>>this is even a plausable event?
>
> You would get thrust only from the stuff that escapes to infinity. You
> can't lift yourself into the air by pulling up on your own shoelaces (at
> least I've never been able to), and you won't get thrust by bouncing
> photons or electrons back and forth.
>
I understand that ;-) I suppose I need to brush up on my gravitational
theory. It was my understanding that gravity distorts the space around it
to the point where two ships traveling in euclidian paralell lines wolould
no longer be travelling in said state after passing a gravitational field.
I was thinking that it would be possible to create some mass that causes
enough of a field that one of those paralell lines would actually return
towards the source.
Mathew Orman
Two real reflecting or refracting points.
On the macro surface of the body (reflection)
Volume of the body (refraction)
On the atomic level it is the shortest path from one atom to the other atom.
Mathew Orman
Robert Kolker
Spaceman wrote:
>
> YUP!
> on some stuff.
Nope. A light beam in free space follows a geodesic. Just like Dr. E
said it does.
Bob Kolker
Eric Gisse
Spaceman
"Charles Allen" <cra...@purdue.edu> wrote in message news:b1sj73$obm$3...@mozo.cc.purdue.edu...
> a straight line with respect to what?
With respect to a straight line.
What is the matter?
You don't know what a straight line is anymore?
Spaceman
"Charles Allen" <cra...@purdue.edu> wrote in message news:b1sjpk$obm$4...@mozo.cc.purdue.edu...
> I understand that ;-) I suppose I need to brush up on my gravitational
> theory. It was my understanding that gravity distorts the space around it
> to the point where two ships traveling in euclidian paralell lines wolould
> no longer be travelling in said state after passing a gravitational field.
That is all parrot speak,
"distorting space" is the same as saying distorting nothing.
space is not curved.
space has no sturcture of it's own.
matter can create structure,
not space alone.
Charles Allen
>> a straight line with respect to what?
>
> With respect to a straight line.
> What is the matter?
> You don't know what a straight line is anymore?
So you're saying a straight line is the timewise shortest possible travel
distance petween two points?
Spaceman
"Charles Allen" <cra...@purdue.edu> wrote in message news:b1tpi8$bl8$1...@mozo.cc.purdue.edu...
No not the shortest "possible" "route".
the shortest period as in "straight line"
The "shortest possible" may end up way to curved and therefore not a "straight line at all".
The shortest length between without need for "possible route at all".
The shortest distance to the other side of the planet is directly through
the middle towards the point you wish to end the line.
The shortest possible route is a joke for "actual distance away"
Gregory L. Hansen
Oh, I get what you're saying now. The ship fires [propellant], getting a
little kick, and then the [propellant] slingshots around [astronomical
object] and hits the ship again, and again, and so on. Where [propellant]
is light, or electrons, or whatever, and [astronomical object] is a
planet or a black hole or whatever it takes.
You could always just say there's a black hole back there. That will turn
anything to any direction if you choose the right orbit. Or a mirror that
reflects light, or a magnetic mirror that reflects a plasma exhaust, or an
induction motor with a U-turn that returns chunks of metal. Supposing
light, it will lose energy with each bounce. I wonder what total impulse
it could provide in that scenario? Seems like a simple problem that I
don't want to work out just now as I sit here at the keyboard.
Mitchell Jones
***{A geodesic, by definition, is the shortest distance between two points
on a curved surface. A surface, by definition, is two dimensional.
Therefore three-dimensional space, by definition, cannot be a geodesic.
Since "a light beam in free space" obviously has three spatial degrees of
freedom, not two, the only curved surface it could follow would be an
imaginary construct which someone fantisized into existence by
deliberately fitting it to the known path of the beam of light. But, in
that case, it would be the fictive surface that followed the path of the
light beam, rather than the other way around--which means: your statement
has no actual physical content whatsoever, and that is also true of the
same words when uttered by "Dr. E." --MJ}***
> Bob Kolker
===============================================
Sci.physics crackpot list and suggested killfile: Charles Cagle, Stephen
Speicher, Mati Meron, Franz Heymann, Mike Varney, Dirk Van de moortel, Bob
Zombiewoof, Old Man.
Mitchell Jones
<cra...@purdue.edu> wrote:
***{A straight line is the *spacewise* shortest distance between two
points. If, for example, A is on one side of a mountain and B is on the
other side, you will have to tunnel through the mountain to follow the
straight line from A to B. Thus while the straight line is the shortest
*distance* between the two points, it will obviously take more time to get
to B that way than by going around the mountain. (Unless the tunnel has
already been dug, of course.) --MJ}***
Spaceman
"Mitchell Jones" <mjo...@jump.net> wrote in message
news:mjones-0602...@66-105-229-96-aus-02.cvx.algx.net...
> ***{A geodesic, by definition, is the shortest distance between two points
> on a curved surface. A surface, by definition, is two dimensional.
> Therefore three-dimensional space, by definition, cannot be a geodesic.
> Since "a light beam in free space" obviously has three spatial degrees of
> freedom, not two, the only curved surface it could follow would be an
> imaginary construct which someone fantisized into existence by
> deliberately fitting it to the known path of the beam of light. But, in
> that case, it would be the fictive surface that followed the path of the
> light beam, rather than the other way around--which means: your statement
> has no actual physical content whatsoever, and that is also true of the
> same words when uttered by "Dr. E." --MJ}***
:)
Charles Allen
>>>>if the following violated some laws of physics.
>>>>
>>>>You have some space ship.
>>>>The ship has reflecting solar sails attached to the front of the ship.
>>>>Somewhere behind the ship there exists an electro-magnetic or
>>>>gravitational field of sufficient magnitude to cause a photon to
>>>>"slingshot" back towards the front of the ship.
>>>>The re-directed photon would reflect off the front sail, slingshot a
>>>>second time, reflect of the other side, and so on.
>>>>
>>
>>>>Second question: Where would the energy to propel the ship come from, if
>>>>this is even a plausable event?
> Oh, I get what you're saying now. The ship fires [propellant], getting a
> little kick, and then the [propellant] slingshots around [astronomical
> object] and hits the ship again, and again, and so on. Where [propellant]
> is light, or electrons, or whatever, and [astronomical object] is a
> planet or a black hole or whatever it takes.
>
> You could always just say there's a black hole back there. That will turn
> anything to any direction if you choose the right orbit. Or a mirror that
> reflects light, or a magnetic mirror that reflects a plasma exhaust, or an
> induction motor with a U-turn that returns chunks of metal. Supposing
> light, it will lose energy with each bounce. I wonder what total impulse
> it could provide in that scenario? Seems like a simple problem that I
> don't want to work out just now as I sit here at the keyboard.
>
*claps hands* that's a much better explination than my origonal post :-)
Big Bird
> A surface, by definition, is two dimensional.
False.
The surface of a three-dimensional volume is two-dimensional, but the
surface of a volume of some other dimension can have any dimension
that you care to work out mathematically.
===============================================
Sci.physics crackpot list and suggested killfile: Mitchell Jones
Mitchell Jones
con...@biosys.net (Big Bird) wrote:
> mjo...@jump.net (Mitchell Jones) wrote in message
news:<mjones-0602...@66-105-229-96-aus-02.cvx.algx.net>...
>
> > A surface, by definition, is two dimensional.
>
> False.
>
> The surface of a three-dimensional volume is two-dimensional, but the
> surface of a volume of some other dimension can have any dimension
> that you care to work out mathematically.
***{All attributes are carried by entities. All entities have three
spatial dimensions. Therefore all surfaces have two spatial dimensions.
Q.E.D.
Let me elaborate.
If you deny premise number one, you have no basis for believing that
sensations have sources--which means: you lose all basis for believing in
the existence of any entity, including yourself. If you deny premise
number two--i.e., if you claim the existence of entities with more than
three spatial dimensions--then I say "Show me." You can't do it, of
course. :-)
Bottom line: your argument is toast.
--Mitchell Jones}***
> ===============================================
> Sci.physics crackpot list and suggested killfile: Mitchell Jones
***{My, my! The above looks to me like an introduction of ad hominems into
our discussion--a "firing of the first shot," so to speak. Well let me
see, this is such an unprecedented situation, what shall I do? :-)
Hey, here's an idea:
____ _ _ _ _ _
| _ \ | | ___ _ __ | | __ | | | | | |
| |_)| | | / _ \ | '_ \ | |/ / | | | | | |
| __/ | | | (_) | | | | | | < |_| |_| |_|
|_| |_| \___/ |_| |_| |_|\_\ (_) (_) (_)
Bye! :-)
--Mitchell Jones}***
================================================
Sci.physics crackpot list and suggested killfile: Charles Cagle, Stephen
Speicher, Mati Meron, Franz Heymann, Mike Varney, Dirk Van de
moortel, Bob Zombiewoof, Old Man, Big Bird.
Craig Graham
Interesting problem. Let's stick with light. Assume two solar sail
spacecraft opposite each other. Assume one fires, for a short time, a
perfectly non-diverging laser beam at the other. Assume both mirrors are
perfect. Photons will bounce between the mirrors and the spacecraft will
accelerate. They're both going along the same line, all is perfect, no
photons are lost from the system. Thrust will decrease over time simply
because of the increase in photon round trip time. The photons do not lose
energy. Momentum is conserved, but energy is blatantly not conserved since
both spacecraft are accelerating away from each other.
Can a photon become redshifted when bouncing off a mirror that is moving
away from it? That would mean that energy truly is being lost from the
photons and could get rid of the problem, but it's not something I've ever
heard of. Feasible if the wave packet takes a finite time to entirely
reflect.
--
Dr. Craig Graham, Software Engineer
Advanced Analysis and Integration Limited, UK. http://www.aail.co.uk/
Big Bird
> sensations have sources--which means: you lose all basis for believing in
> the existence of any entity, including yourself.
I do not believe anything whatsoever. "Belief" is not a mode of
operation I engage in. In particular, the very *idea* of "belief in
ones own existence" is proof positive that you are a robot, a
mechanism, a trained puppet without any kind of self-awareness. See,
for example here:
http://users.lycaeum.org/~greyfox/certainty.html
Every self-aware being in the universe *knows* that it exists, for it
is this knowledge that *makes* it a self-aware being: the knowledge of
its own existence.
> If you deny premise
> number two--i.e., if you claim the existence of entities with more than
> three spatial dimensions--then I say "Show me." You can't do it, of
> course. :-)
Yes, I can. It isn't even terribly hard.
Just as it isn't terribly hard to "show you" atoms. It is so easy that
the classical greeks already figured out atoms, but the retards like
yourself insisted that"show" means "visible to the naked eye" and so
you deny the existence of atoms because YOU can't "see" them.
Funny how we've been able to "show" things that are invisible to the
naked eye for a long time now. We can "show" that air exists, that
electromagnetic interactions exist, that stars exist that are to faint
for the naked eye. At some point your insistence that things don't
exist because you cannot see them with the naked eye becomes quite
silly.
> > ===============================================
> > Sci.physics crackpot list and suggested killfile: Mitchell Jones
>
> ***{My, my! The above looks to me like an introduction of ad hominems into
> our discussion--a "firing of the first shot," so to speak.
It is a direct copy of your .signature. If you find it insulting, then
you're merely admitting how insulting you are yourself.
I am merely rubbing your nose in your own shit, as it seems to be the
only way to train lower life forms not to soil the carpet...
Ed Keane III
Craig Graham <cr...@twolips-translations.co.uk> wrote in message
news:b1vui5$fgj$1
> Can a photon become redshifted when bouncing off a mirror that is moving
> away from it? That would mean that energy truly is being lost from the
> photons and could get rid of the problem, but it's not something I've ever
> heard of. Feasible if the wave packet takes a finite time to entirely
> reflect.
It would become redshifted. It can even move the mirror itself.
As for the time the *bounce* takes the process is instantaneous.
The amount of redshift depends on relative motion and on how
tightly bound the electrons are in the reflecting material The
energy that is lost in this redshift is transferred to momentum
and heat.
Would someone like to discuss what physics has to say about
whether it takes a finite time to *entirely reflect*?
Craig Graham
> Craig Graham <cr...@twolips-translations.co.uk> wrote in message
> news:b1vui5$fgj$1
> It would become redshifted. It can even move the mirror itself.
> As for the time the *bounce* takes the process is instantaneous.
> The amount of redshift depends on relative motion and on how
> tightly bound the electrons are in the reflecting material The
> energy that is lost in this redshift is transferred to momentum
> and heat.
>
> Would someone like to discuss what physics has to say about
> whether it takes a finite time to *entirely reflect*?
I don't see how an instantaneous bounce can generate a redshift; if time is
zero then the mirror does not move at all during the event.
My feeling is it does take a finite time to reflect- as I recall, a photon
is considered a wave packet and the position of any point-like particle is
indeterminate within that packet. Since the length of the non-infinitesimal
amplitude part is finite the reflection time will also be finite, and hence
the mirror will be in a different position at the end of the event than at
the start. Alas, it's been years since I last looked in Eisberg&Resnick.
G=EMC^2 Glazier
ship is moving at 35,000 mph you are ready to retire from NASA. Bert