Acceleration/Deceleration

[michel123456]

In the rocket frame, the length is contracted by gamma; the rocket observer measures a shorter length as the speed increases. The resulting speed calculation from that frame will never exceed c.

 

In the rocket frame, the length is not contracted. The length is contracted as seen from another FOR. The traveler notices nothing, the lengths are measured by him as we do here on Earth: he doesn't know whether lengths are contracted or not. And you accepted inconsciously that speed increases.

 

The event "traveling" is measured differently from different observers. Relativity is the Theory that permits to calculate what each observer will measure. The one will see lengths contracting, the other will not, according to their relative displacement. None of the observers knows the truth. It's all about how one observer sees the other. It's all about observation.

 

When we observe a traveler at speed near to c, we observe his mass increasing. Reversely, the traveler looks at us and observes that our mass is increasing. What is happening? Does our mass increase because we sent some fellow to another galaxy? I don't think so. It is only deformed observation, ruled by Relativity.

 

As an analogy, think of the deformations caused by perspective. It is possible to build a geometrical theory that will assume that the edges of a road join at horizon, and make that theory work in any circumstance. In this theory, the distance to horizon would always be the same for all observators. No matter the velocity, the distance to horizon is a constant.

But do the edges of the road really coincide at horizon, or are they parallel?

 

Where is reality, and where is observation?

Edited June 26, 2010 by michel123456

[Moontanman]

Evidently i am just not intelligent enough to wrap my head around the idea of relativity. In my mind's eye I can't get around the idea that nearing the speed of light anything with mass would wrap it's self in a black hole and disappear from our universe...

[swansont]

In the rocket frame, the length is not contracted. The length is contracted as seen from another FOR. The traveler notices nothing, the lengths are measured by him as we do here on Earth: he doesn't know whether lengths are contracted or not. And you accepted inconsciously that speed increases.

 

The traveler sees his ship and anything on board as normal, but all external objects and distances will be contracted in the direction of his travel. If the markers were 1 LY apart, and he's going at 0.995c (gamma=10), then he will see the markers as being 0.1 LY apart.

 

The event "traveling" is measured differently from different observers. Relativity is the Theory that permits to calculate what each observer will measure. The one will see lengths contracting, the other will not, according to their relative displacement. None of the observers knows the truth. It's all about how one observer sees the other. It's all about observation.

 

When we observe a traveler at speed near to c, we observe his mass increasing. Reversely, the traveler looks at us and observes that our mass is increasing. What is happening? Does our mass increase because we sent some fellow to another galaxy? I don't think so. It is only deformed observation, ruled by Relativity.

 

We've been through this in other threads just recently; mass as normally defined does not increase. Mass redefined as E/c^2, i.e. the total energy, will change, because the kinetic energy changes.

[Moontanman]

Ok, so IF It were possible to be an outside observer in a universe wide time frame the moving object's mass increase with speed would not be real? I'm trying I really am...

[Cap'n Refsmmat]

Isn't 'application' hint that you 'applied' it?

Applied.. as opposed to theoretical....?

 

Computer modeling of relativistic events is an application of relativity, but not necessarily an experiment. "Application" means you apply it to something, but that something does not have to be an experiment. It could be a spreadsheet.

[swansont]

Ok, so IF It were possible to be an outside observer in a universe wide time frame the moving object's mass increase with speed would not be real? I'm trying I really am...

 

Not according to the definition of mass that is usually used.

 

Some people like to redefine mass to be proportional to the total energy. Unfortunately, instead of calling it "foo," they also call it mass. Foo increases with speed. Foo= E/c^2

[michel123456]

The traveler sees his ship and anything on board as normal, but all external objects and distances will be contracted in the direction of his travel. If the markers were 1 LY apart, and he's going at 0.995c (gamma=10), then he will see the markers as being 0.1 LY apart.

 

Emphasis mine.

So you really believe contraction is really happening.

 

If speed is relative, and you agreed about that, contraction is relative too. The traveler is as good observator as anyone else. The traveler observes that on Earth the distances are contracted.

......

 

I can't do anything else for you Swansont.

You have to unscrew something in your brain by yourself. I can't do that for you.

 

At the antipods, people observe imaginary roads.

[swansont]

Emphasis mine.

So you really believe contraction is really happening.

 

Yes. It is a result of relativity, just as time dilations is.

 

If speed is relative, and you agreed about that, contraction is relative too. The traveler is as good observator as anyone else. The traveler observes that on Earth the distances are contracted.

 

Distances on earth, and everywhere else, according to the rocket observer. Anything moving relative to him is subject to relativistic effects.

 

I can't do anything else for you Swansont.

You have to unscrew something in your brain by yourself. I can't do that for you.

 

No worries. I'm good.

[Sisyphus]

michel,

 

Instead of unconnected markers at origin and destination, imagine that there is a physical ruler stretching between them. If the ruler is 1LY long in its own reference frame, in the reference frame in which that ruler is moving 0.995C (i.e., the rest frame of the spaceship), it is contracted to 0.1LY. Therefore, observers on the spaceship will say they have traveled 0.1LY, while observers on Earth will say the spaceship has traveled 1LY.

Edited June 29, 2010 by Sisyphus

[michel123456]

No.

There is no preferential referential frame.

Earth's FOR is not THE referential frame.

The traveler is at rest in his own FOR. He believes he is the absolute FOR and decide that the ruler on Earth is contracting, and that time on Earth is under dilation.

 

Your descriptions are just as like we knew which one is traveling and which one is at rest. We don't know that.

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No worries. I'm good.

 

That is very worrying.

[swansont]

No.

There is no preferential referential frame.

Earth's FOR is not THE referential frame.

The traveler is at rest in his own FOR. He believes he is the absolute FOR and decide that the ruler on Earth is contracting, and that time on Earth is under dilation.

 

Your descriptions are just as like we knew which one is traveling and which one is at rest. We don't know that.

 

Which is precisely why the traveler cannot and will not rely on an earth-based measurement for distance. He will think it's wrong when measured from his own frame.

 

The spreadsheet you linked to was using an absolute frame. Not me.

[michel123456]

Which is precisely why the traveler cannot and will not rely on an earth-based measurement for distance. He will think it's wrong when measured from his own frame.

 

The spreadsheet you linked to was using an absolute frame. Not me.

 

Maybe.

But you believe contracting of distance really physically happens.

[Sisyphus]

Depends what you mean by "physically happens." Nothing changes, but it is true that the distance between origin and destination really is different in two different reference frames. Earth-destination is moving in the ship's rest frame, therefore it is compressed.

[michel123456]

Depends what you mean by "physically happens." .

 

Language barrier?

 

Physically happens, is really happening, pragmatically, Reality, fact, occurence.

[swansont]

Language barrier?

 

Physically happens, is really happening, pragmatically, Reality, fact, occurence.

 

Length contraction, like time dilation, is a real phenomenon. Reality, however, is frame-dependent. Using terms like "physically happens" implies that there is an objective measurement that all will agree on, and that's at odds with relativity. We can agree whether an event happens, but not about the time and location, and whether it was simultaneous with some other event.

[AlphaSheeppig]

My personal opinion (as meaningless as it is) is that the contraction and dilation does not "physically happen", because I will never see myself contract or fell any time dilation. I will only ever see it happen to other objects as they move toward or away from me or I move away from or toward them or what ever. It is only noticed by an observer, so it's sort of like an illusion (but with measurable effects). Slightly flawed logic, I know, but it's what makes sense to me.

[michel123456]

Length contraction, like time dilation, is a real phenomenon. Reality, however, is frame-dependent.

 

It is not a language barrier.

It is a conceptual barrier.

For me, if reality is frame-dependent, (and I surely agree on this) length contraction & time dilation cannot be a real phenomenon.

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Using terms like "physically happens" implies that there is an objective measurement that all will agree on, and that's at odds with relativity. We can agree whether an event happens, but not about the time and location, and whether it was simultaneous with some other event.

 

The "objective measurement that all will agree on" is the one which coincides with the FOR of the observed phenomena. It is the one we choose for determining the rest mass.

[rigney]

Moon, you've more than likely studied the animations of Einstein's, "eleavator experiment". It doesn't stop there, but is merely a prelude to the mans genius. I googled it up and, Wow!. The simplicity of these explanations is that they come across as so mundane, even I can understand them. And without the numbers or formulas, of which; would make it impossible for me.

Edited July 1, 2010 by rigney

[swansont]

It is not a language barrier.

It is a conceptual barrier.

For me, if reality is frame-dependent, (and I surely agree on this) length contraction & time dilation cannot be a real phenomenon.

 

This is contradictory. Do you agree that the observers will measure different distances and times, depending on their frame?

 

The "objective measurement that all will agree on" is the one which coincides with the FOR of the observed phenomena. It is the one we choose for determining the rest mass.

 

No, rest mass is an invariant. It does not depend on the frame of reference, which is one reason why it's useful.

 

There is no FoR for the observed phenomena if all observers in all frames can observe it. There is no physics reason to choose one frame over another frame. Choosing an object's rest frame would be a convention by agreement, but not one dictated by physics.

[Moontanman]

Moon, you've more than likely studied the animations of Einstein's, "eleavator experiment". It doesn't stop there, but is merely a prelude to the mans genius. I googled it up and, Wow!. The simplicity of these explanations is that they come across as so mundane, even I can understand them. And without the numbers or formulas, of which; would make it impossible for me.

 

I have seen them, i really have no problem wrapping my mind around the concepts ... all except one, time dilation, I think the conventional conclusion is fatally flawed. I can see how mass is frame dependent, speed up and your mass appears to be greater than the people you left behind, to you they appear to be more massive and contracted but the time contraction is only real for the guy who is moving, when he speeds up to him it looks like time has slowed down for the people he left, to them his time looks slower but when he comes back his time is still real but he find his observation of the people he left behind was wrong.

 

You could travel to the Andromeda Galaxy and back in one human life time but no matter how time dilated your take off point looks to you when you get back your time has been slower but the observed slowness of the people you left behind is not real.

 

Ok, go ahead, whip me, beat me, make me write bad checks....

[michel123456]

This is contradictory. Do you agree that the observers will measure different distances and times, depending on their frame?

 

Yes.

They will measure different distances & times. I agree on that.

But what they will measure will not be "real". When thousands of different observers are observing one single phenomena, they will all disagree on what they measure. From that fact I conclude that what one observer will measure cannot be considered as "really happening". I conclude that what one observer will measure is a deformation of what really happens. And all thousands observers will all measure different deformations of one single undeformed reality.

 

Look:

You believe I am contradicting, I believe you are contradicting.

It is useless to continue that way. I will make a pause and rethink the subject. I suggest you do the same.

[Sisyphus]

You emphasize "measure" as if you think it's an illusion or something. In the Earth's rest frame, the spaceship really is shorter, and it's time really does pass more slowly. And vice versa for the ship's rest frame. This has real physical consequences, not just appearances.

[swansont]

I have seen them, i really have no problem wrapping my mind around the concepts ... all except one, time dilation, I think the conventional conclusion is fatally flawed. I can see how mass is frame dependent, speed up and your mass appears to be greater than the people you left behind, to you they appear to be more massive and contracted but the time contraction is only real for the guy who is moving, when he speeds up to him it looks like time has slowed down for the people he left, to them his time looks slower but when he comes back his time is still real but he find his observation of the people he left behind was wrong.

 

You could travel to the Andromeda Galaxy and back in one human life time but no matter how time dilated your take off point looks to you when you get back your time has been slower but the observed slowness of the people you left behind is not real.

 

Ok, go ahead, whip me, beat me, make me write bad checks....

 

You are at odds with actual experiments. This is not some hypothetical musing or dorm-room conjecture. If you move clocks, their rates change. When you compare them to clocks that did not move, they read out different times. When you put clocks in a different gravitational potential, it ticks at a different rate.

 

None of this depends on the specific type of clock. It's not a mechanical effect — the clocks are not broken on some way.

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Yes.

They will measure different distances & times. I agree on that.

But what they will measure will not be "real". When thousands of different observers are observing one single phenomena, they will all disagree on what they measure. From that fact I conclude that what one observer will measure cannot be considered as "really happening". I conclude that what one observer will measure is a deformation of what really happens. And all thousands observers will all measure different deformations of one single undeformed reality.

 

Look:

You believe I am contradicting, I believe you are contradicting.

It is useless to continue that way. I will make a pause and rethink the subject. I suggest you do the same.

 

No such thing as a single undeformed reality. There is no preferred frame of reference from which to observe things. As I mentioned above, moving clocks really do run slow. These effects are measurable and have been measured.

 

I have ~100 years of experimental evidence on my side. What have you got?

[rigney]

While I can't disagree with time slowing or speeding up in "time pieces" at different speeds and altitudes since it is a fact, how is this correlation formulated into a Moon, Mars, and other projected space missions that somehow always seems to come out right?

Edited July 1, 2010 by rigney

[swansont]

While I can't disagree with time slowing or speeding up in "time pieces" at different speeds and altitudes since it is a fact, how is this correlation formulated as part of a moon, Mars, or other projected space mission that somehow always seem to come out right?

 

Because we know the theory, and we let smart people work on the projects.