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# The Twins Paradox and the speed of light

Author Topic:   The Twins Paradox and the speed of light
NoNukes
Inactive Member

 Message 181 of 230 (629986) 08-21-2011 7:25 PM Reply to: Message 180 by Maartenn10008-21-2011 5:05 PM

Re: gravitational theory of relativity
And I do not claim that it's science.
Good.
Hubble discovered that all starclusters are redshifting, from your point of view. Wherever you are, you will see everything redshifting at the bounderies of space and time-measurement form your point of view.
Why doesn' you see it between Earth and the moon? Or Earth and Mars?
First, the red shift produced by the expansion of space is extremely tiny on the scale of the solar system. Taking the Hubble constant to be 70 (km/s)/Mpc and the distance from Earth and Mars to be about 2.6 AU which is approximately the maximum separation between the two planets, gives a velocity on the order of 10^-9 km/second for the rate of expansion of space between Earth and Mars. That rate of expansion would produce an undetectable amount of red shift.
Of course even that tiny expansion of space does not translate into the Earth and Mars moving apart because:
The earth and moon, and the entire solar system are bound together by gravity, so that the separation between them is not directly affected by the expansion of space within the solar system. It's as if the earth and mars were connected together by relatively strong springs. The springs would oppose a an expansion force attempting to separate earth and mars. The expansion of space would not result in a velocity between earth and mars, but would instead produce an extremely tiny and undetectable increased between the planets. So there would actually be no expansion based redshift between earth and mars at all.
Finally, earth and mars, due to their orbital motions have their own relative motions sometimes towards each other and sometimes away. In fact galaxies also have proper motions relative to each other. Some galaxies are moving towards us and exhibit blue shift rather than red shift. So it is not even true that all star clusters are red shifting.

 This message is a reply to: Message 180 by Maartenn100, posted 08-21-2011 5:05 PM Maartenn100 has replied

 Replies to this message: Message 182 by Maartenn100, posted 08-27-2011 9:33 PM NoNukes has seen this message but not replied

Maartenn100
Member (Idle past 4136 days)
Posts: 39
From: Belgium Antwerp
Joined: 08-13-2011

 Message 182 of 230 (630788) 08-27-2011 9:33 PM Reply to: Message 181 by NoNukes08-21-2011 7:25 PM

Re: gravitational theory of relativity
Interesting.
I made two (short) videos of my theory:
and
have fun.
Edited by Maartenn100, : No reason given.

 This message is a reply to: Message 181 by NoNukes, posted 08-21-2011 7:25 PM NoNukes has seen this message but not replied

Bolder-dash
Member (Idle past 3174 days)
Posts: 983
From: China
Joined: 11-14-2009

 Message 183 of 230 (680063) 11-17-2012 12:57 PM

I enjoy this discussion, but as in everything in life, one must approach all "facts" with some skepticism. Here is a paradox I have with this paradox: If someone cares to answer it, (preferably without math formulas) I would be most grateful:
Premise: When one object is accelerating it will experience time slower relative to an object not accelerating.
So, what if the object (one of the twins in this case) is simply going in circles around the other twin, and they can see each other?
What if one of the twins is not changing his orientation at all, but is simply spinning on a fixed axis at close to the speed of light, is the parts on his body furthest from the axis experiencing time at a different rate from the parts of his body closer to the axis (which are obviously moving slower)?
Take it another step further...the object that is moving is a pocket-watch-does the way in which it is moving matter? Can it be spinning around an axis? How about if you could stare at the center of the face of the pocket-watch, but the numbers are spinning clockwise (or counterclockwise if you prefer)?
And what if it is just part of the watch that is accelerating, like a ring around the outside of it? Can parts of the watch age more while other parts age less?
And to take it even one step further if I may. What if one of the twins (or a watch) is simply vibrating at close to the speed of light, will it experience time differently than the twin not vibrating, even though they have not moved apart from each other at all? It is after all moving while it is being vibrated, correct?
A long time ago I asked this question, and the replies I got had to do with acceleration and deceleration as being the reason why a circular path is not equal to a linear path.
This seems to be an incorrect answer to my question, as according to this article Blog | Earthlink: Special relativity says nothing about acceleration or deceleration, but is simply concerned with the speed of the reference frame. It doesn't matter how it obtains that speed.
So I am wondering if anyone cares to give it another shot. What is the difference between traveling in a circle (or even just spinning around and axis), and traveling in a straight line according to the theory of relativity?

 Replies to this message: Message 184 by NoNukes, posted 11-17-2012 1:46 PM Bolder-dash has not replied Message 185 by NoNukes, posted 11-17-2012 3:54 PM Bolder-dash has replied

NoNukes
Inactive Member

 Message 184 of 230 (680071) 11-17-2012 1:46 PM Reply to: Message 183 by Bolder-dash11-17-2012 12:57 PM

Special relativity says nothing about acceleration or deceleration, but is simply concerned with the speed of the reference frame.
The above analysis not correct. An inertial reference frame is a frame in which there is no acceleration. This means that neither speed nor the direction associated with the speed can change. The forms of the time dilation and length contraction equation that everyone is used to using assume inertial reference frames. Special relativity can be used to handle accelerated frames, but the analysis is a bit difficult. In essence, the apparent paradox results from taking a short cut with the analysis from the view point of traveling twin.
The itineraries of the stay at home twin and the traveling twin are not symmetric. While the stay at home twin travels at constant velocity as measured any inertial reference frame, there is no single inertial reference frame from which the same can be said for the traveling twin. This is true regardless of whether the traveling twin moves in a circle at constant speed or travels out to a point and returns along a straight line path.
There is an explanation on this board from either cavediver or Son Goku in which the two paths are drawn on a space time diagram. I'd recommend looking up that diagram and the associated explanation.
Edited by NoNukes, : No reason given.
Edited by NoNukes, : No reason given.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison.
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass

 This message is a reply to: Message 183 by Bolder-dash, posted 11-17-2012 12:57 PM Bolder-dash has not replied

NoNukes
Inactive Member

 Message 185 of 230 (680098) 11-17-2012 3:54 PM Reply to: Message 183 by Bolder-dash11-17-2012 12:57 PM

The link below gives an explanation of the twin paradox and provides a space-time diagram of the relevant events from the perspective of the stationary twin and the traveling twin. The role of acceleration in explaining the distinction between the two views is explained.
Yet another explanation.
Twin Paradox (from Einstein Light: relativity in film clips and animations)
Edited by NoNukes, : No reason given.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison.
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass

 This message is a reply to: Message 183 by Bolder-dash, posted 11-17-2012 12:57 PM Bolder-dash has replied

 Replies to this message: Message 186 by Bolder-dash, posted 11-18-2012 4:19 AM NoNukes has replied Message 188 by Bolder-dash, posted 11-18-2012 5:18 AM NoNukes has replied

Bolder-dash
Member (Idle past 3174 days)
Posts: 983
From: China
Joined: 11-14-2009

 Message 186 of 230 (680159) 11-18-2012 4:19 AM Reply to: Message 185 by NoNukes11-17-2012 3:54 PM

Re: Twin paradox space time diagram
Nonukes, thanks for the attempt, but I am not sure you really read very clearly what I am questioning. You simply referred me back to an explanation of the twins paradox, without addressing the circling or direction problem with the paradox.
When I first proposed the problem with the twins paradox, I mentioned that the twins don't need to separate at all in order for one to move at or near the speed of light. One could just be spinning in a circle around the other, and thus still remain in the same approximate vectors. They could both look at the same clock.
Now Iblis tried to make the claim that because twin number 2 was moving in a circular direction, and thus was decelerating as much as he was accelerating, so that would nullify the effects of time dilation. But that is just false, and a misunderstanding of the Special Theory of Relativity.
Acceleration has nothing to do with it, it merely deals with the speed, it doesn't matter how it achieved that speed, the history of accelerating or decelerating before it achieved any speed is irrelevant.
From what I now understand, Einstein wasn't even able to answer the question of the twins paradox. It appears to just be a completely fabricated fun scientific exercise, with no basis in fact. Just anther way of playing with numbers, to create false ideas. That is why many try to restrict the paradox to one direction, because it makes it appear to satisfy a formula. But why only one direction, nobody can seem to explain that other then it is just convenient for making a paradox.
And as a side point, if all things are relative when considering speed, and one can always reverse which is the moving object, and which is the object at rest when comparing two frames of reference, why in my example can only one experience g force? In other words, if both are moving relative to the other, why does the twin circling feel g force, while the twin being circled feel nothing? It seems only one can be said to be truly moving.

 This message is a reply to: Message 185 by NoNukes, posted 11-17-2012 3:54 PM NoNukes has replied

 Replies to this message: Message 187 by cavediver, posted 11-18-2012 5:14 AM Bolder-dash has not replied Message 195 by NoNukes, posted 11-18-2012 9:44 AM Bolder-dash has replied

cavediver
Member (Idle past 3188 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 (1)
 Message 187 of 230 (680160) 11-18-2012 5:14 AM Reply to: Message 186 by Bolder-dash11-18-2012 4:19 AM

Re: Twin paradox space time diagram
Nonukes, thanks for the attempt, but I am not sure you really read very clearly what I am questioning.
Yes he did.
Acceleration has nothing to do with it
No, it has everything to do with it.
From what I now understand, Einstein wasn't even able to answer the question of the twins paradox.
where do you get this crap? He answered it in multiple ways. Just as with many aspects of Relativity (General and Special), there are multiple answers,explanations, or analogies because our non-relativistic intuition sees relativistically unified concepts as distinct.
And as a side point, if all things are relative when considering speed, and one can always reverse which is the moving object
No, you can't. Not when acceleration is involved.
...why in my example can only one experience g force? In other words, if both are moving relative to the other, why does the twin circling feel g force, while the twin being circled feel nothing?
But that's impossible, because, as you have so correctly stated, acceleration has nothing to do with it... it's a mystery.
It seems only one can be said to be truly moving.
Oh my god, you mean you have found an asymetry between the two travellers???? But, but, this changes, like EVERYTHING. Who would have guessed?
If you are seriously interested in this stuff, why not stop reading crap from the internet such as that paper to which you linked, and treat yourself to a copy of Misner Thorne and Wheeler's "Gravitation". It is a graduate text, but much of their Track 1 material (minus the mathematics) can be understood by an interested reader with sufficient determination.
If nothing else, it will open your eyes to level of thought that has gone into 20th Century Relativistic physics, and hopefully convince you that an interested amateur has as much chance of critiquing the science as a paper plane maker has of finding the design flaws in an Airbus A380.

 This message is a reply to: Message 186 by Bolder-dash, posted 11-18-2012 4:19 AM Bolder-dash has not replied

Bolder-dash
Member (Idle past 3174 days)
Posts: 983
From: China
Joined: 11-14-2009

 (1)
 Message 188 of 230 (680161) 11-18-2012 5:18 AM Reply to: Message 185 by NoNukes11-17-2012 3:54 PM

Re: Twin paradox space time diagram
In reading what you wrote again, I guess you did try to address the question of circular motion, but I still believe it is not answered adequately enough. I am having a hard time understanding why inertial and non inertial frames of reference would effect ones outcome in spacetime. Why does the the twins paradox become invalid once we remove single inertial frames? Isn't it simply because we have a cute little math formula which gets bugged up once we scrutinize it?
What are the reality of physics that allows one inertial frame to cause a paradox of time, while a shifted inertial frame invalidates the outcome?
In other words, aren't we throwing in these conditions of single inertial frames just for the sake of protecting the math formula, without any other valid reason for doing so?
Edited by Bolder-dash, : No reason given.

 This message is a reply to: Message 185 by NoNukes, posted 11-17-2012 3:54 PM NoNukes has replied

 Replies to this message: Message 189 by cavediver, posted 11-18-2012 5:35 AM Bolder-dash has replied Message 194 by NoNukes, posted 11-18-2012 9:22 AM Bolder-dash has not replied

cavediver
Member (Idle past 3188 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 (1)
 Message 189 of 230 (680162) 11-18-2012 5:35 AM Reply to: Message 188 by Bolder-dash11-18-2012 5:18 AM

Re: Twin paradox space time diagram
What are the reality of physics that allows one inertial frame to cause a paradox of time, while a shifted inertial frame invalidates the outcome?
Space-time is four-dimensional. Points in space-time are called events. Let's say event A occurs before event B ("before" meaning that it is possible that a signal can be sent from A to B without exceeding the speed of light.) For example, event A is 4pm GMT 18/11/2012 on Earth, and event B is 4pm GMT 18/11/2013 also on Earth.
The 4-dimensional distance along the 4-d path taken through space-time from A and B is the time experienced. Because the distance measure on 4d space-time is not your simple Pythagoras $\color{white} d^2=x^2+y^2+z^2$ but the more complex Minkowski metric $\color{white} d^2=t^2-x^2-y^2-z^2$, this means that the more curved the path through space-time, the *shorter" the distance (and hence time) between the two events.
To create a curved path through space-time, you will need to utilise non-inertial frames. i.e. you will need to accelerate / decelerate.
Thus, if non-inertial frames are involved in your path through space-time from A to B, you know that your path will be more curved than a path that does not involve non-inertial frames. And by simple 4d Minkowski geometry, your path will therefore be shorter, and you will experience less time on your path.

 This message is a reply to: Message 188 by Bolder-dash, posted 11-18-2012 5:18 AM Bolder-dash has replied

 Replies to this message: Message 190 by Bolder-dash, posted 11-18-2012 6:25 AM cavediver has replied

Bolder-dash
Member (Idle past 3174 days)
Posts: 983
From: China
Joined: 11-14-2009

 Message 190 of 230 (680164) 11-18-2012 6:25 AM Reply to: Message 189 by cavediver11-18-2012 5:35 AM

Re: Twin paradox space time diagram
cavediver,
Do you wish to make a wager as to whether or not Einstein believed he was able to satisfactorily answer the twins paradox problem?
Secondly, why does an accelerated-decelerated path necessary become a curved path?

 This message is a reply to: Message 189 by cavediver, posted 11-18-2012 5:35 AM cavediver has replied

 Replies to this message: Message 191 by cavediver, posted 11-18-2012 6:51 AM Bolder-dash has replied

cavediver
Member (Idle past 3188 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 Message 191 of 230 (680167) 11-18-2012 6:51 AM Reply to: Message 190 by Bolder-dash11-18-2012 6:25 AM

Re: Twin paradox space time diagram
Do you wish to make a wager as to whether or not Einstein believed he was able to satisfactorily answer the twins paradox problem?
Not sure exactly how we're going to prove that one without reanimating Albert, and last time I saw his brain, it had been thoroughly chopped up - so I wouldn't be entirely confident in what we'd get back.
Every attempt to show that Einstein was confused by the Twin's Paradox that I have seen was written by an idiot who while being thoroughly clueless of relativistic physics, was convinced that he understood it on a par with the rest of us professionals. So, bring it on...
Secondly, why does an accelerated-decelerated path necessary become a curved path?
Because that is what "curved" means... you know, 2nd derivatives and higher of displacement with respect to the time coordinate being non-zero, and all that?
Edited by cavediver, : No reason given.

 This message is a reply to: Message 190 by Bolder-dash, posted 11-18-2012 6:25 AM Bolder-dash has replied

 Replies to this message: Message 192 by Bolder-dash, posted 11-18-2012 7:09 AM cavediver has replied

Bolder-dash
Member (Idle past 3174 days)
Posts: 983
From: China
Joined: 11-14-2009

 Message 192 of 230 (680169) 11-18-2012 7:09 AM Reply to: Message 191 by cavediver11-18-2012 6:51 AM

Re: Twin paradox space time diagram
First, I suppose we could use quotes by Einstein himself, that display his own doubts about solving the twins paradox, if that suits you. Really, I thought you did this for a living, I would hate to embarrass you by having an uneducated fop like me, show you the emptiness of your arrogance.
Secondly, so if we have acceleration and declaration as part of the equation of the paradox, then the paradox becomes invalid, because it no longer deals with Special Relativity? And we can't accelerate and decelerate in a straight line, because by definition acceleration and deceleration is curved?

 This message is a reply to: Message 191 by cavediver, posted 11-18-2012 6:51 AM cavediver has replied

 Replies to this message: Message 193 by cavediver, posted 11-18-2012 7:27 AM Bolder-dash has replied

cavediver
Member (Idle past 3188 days)
Posts: 4129
From: UK
Joined: 06-16-2005

 (2)
 Message 193 of 230 (680170) 11-18-2012 7:27 AM Reply to: Message 192 by Bolder-dash11-18-2012 7:09 AM

Re: Twin paradox space time diagram
First, I suppose we could use quotes by Einstein himself, that display his own doubts about solving the twins paradox
Well, you can try. Of course, there would by necessity be times when he would be unsure - sure as before he had even entertained Special Relativity, and around the time that the apparent clock paradox (as he termed it) first occured to him. But I'm sure you have something much more concrete than that...
Really, I thought you did this for a living
Not for the best part of 20 years. And then, history has never been my strong point.
I would hate to embarrass you by having an uneducated fop like me, show you the emptiness of your arrogance.
What part of "bring it on" did you not understand?
Secondly, so if we have acceleration and declaration as part of the equation of the paradox, then the paradox becomes invalid, because it no longer deals with Special Relativity?
Why does it not deal with Special Relativity? Special Relativity is essentially the physics of Minkowski spactime. You're not believing all that bullshit about acceleration not being part of Special Relativity are you?
And we can't accelerate and decelerate in a straight line, because by definition acceleration and deceleration is curved?
accelerating in a straight line in 3d, is creating a curve in 4d. Did you not look at time-distance graphs in school for uniform motion and accelerating motion? Can you not see the connection?
ABE:
I would hate to embarrass you by having an uneducated fop like me, show you the emptiness of your arrogance.
Arrogance?????
You mean something like:
Nonukes, thanks for the attempt, but I am not sure you really read very clearly what I am questioning.
Acceleration has nothing to do with it, it merely deals with the speed
Einstein wasn't even able to answer the question of the twins paradox.
It appears to just be a completely fabricated fun scientific exercise, with no basis in fact.
Just anther way of playing with numbers, to create false ideas.
You need to look into the mirror Bolder-dash, and perhaps you'll understand why I treat many of your comments with the contempt they deserve.
Edited by cavediver, : No reason given.
Edited by cavediver, : graph

 This message is a reply to: Message 192 by Bolder-dash, posted 11-18-2012 7:09 AM Bolder-dash has replied

 Replies to this message: Message 198 by Bolder-dash, posted 11-18-2012 10:48 AM cavediver has replied

NoNukes
Inactive Member

 Message 194 of 230 (680174) 11-18-2012 9:22 AM Reply to: Message 188 by Bolder-dash11-18-2012 5:18 AM

Re: Twin paradox space time diagram
In reviewing what.you posted, I note that your original reference more than adequately explains the twin paradox.
At this point, I think you should take on some of the effort in understanding. Try drawing the space time drawings for the scenario you want to examine.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison.
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass

 This message is a reply to: Message 188 by Bolder-dash, posted 11-18-2012 5:18 AM Bolder-dash has not replied

NoNukes
Inactive Member

 (1)
 Message 195 of 230 (680177) 11-18-2012 9:44 AM Reply to: Message 186 by Bolder-dash11-18-2012 4:19 AM

Re: Twin paradox space time diagram
Why in my example can only one experience g force?
The twin that fires his retro rockets will feel the acceleration. The other twin will not. How could this be otherwise? Surely that should be enough to show you that acceleration is not "relative"

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison.
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass

 This message is a reply to: Message 186 by Bolder-dash, posted 11-18-2012 4:19 AM Bolder-dash has replied

 Replies to this message: Message 196 by Bolder-dash, posted 11-18-2012 10:21 AM NoNukes has seen this message but not replied

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