Twin paradox (Pete and MacM)

[MacM]

****From Cut and paste of your post.

"One can compute at which point the mass of the fuel required to keep the ship accelerating becomes so high that its self gravity would cause it to collapse as a black hole. Of course the observer (assumed human) would have been crushed long before due to the intense gravitational field of his own ship"

Which of course is utter nonsense since the pilot, spacecraft, etc all see absolutely no change in mass, time, etc. of their own inertial system.

 

[MacM]

Mac, all you've shown is that simultaneity is not invariant across refrence frames. According to A, when A's clock stopped (at 36,000 ticks), B's clock read 15,692 ticks. According to B, when B's clock stopped, A's clock read 6,840 ticks. According to A, both clocks stopped simutaneously. According to B, they didn't. This is exactly what relativity predicts.

Your faulty conclusion comes from an invalid, unspoken, assumption that simultaneity *is* invariant.

P.S. Why would B predict that A's clock would stop at 6,840 when he knew ahead of time that it would stop at 36,000, since that is what you set it to stop at? There is nothing requiring that A's clock stop when B's clock does in B's reference frame.

Don't let the test throw you a curve. It has been done in this manner simply because members here would never agree on a method of synchronizing clocks to perform the test of time dilation affects of relative velocity according to Relativity.

By assuming Relativity valid and using the timers was to insure they stopped simultaneously, according to Relativity. It is nothing more than a means of comparing numbers and of course makes no actual test.

Now the oint was that according to "A" when it reaches 36,000 seconds, B would has slowed down and only be 15,692 seconds. Further according to B A slowed down such that after 15,692 seconds at B's local time "A" would have only accumulated 6,840 seconds. Stopping the clocks simultaneouls according to Relativity shows that this is not the case "A" actually reads 36,000 seconds, not B's viw of "A" of 6,840 seconds. Hence B's view is NOT physical reality, it is only an illusion of motion, a perception and not actual time dilation.

 

[Persol]

Which of course is utter nonsense since the pilot, spacecraft, etc all see absolutely no change in mass, time, etc. of their own inertial system.

That's not what it's saying. It is saying that you need a lot of fuel... more fuel then is possible. If you manage to get that much fuel, you just made a black hole.

 

[MacM]

That's not what it's saying. It is saying that you need a lot of fuel... more fuel then is possible. If you manage to get that much fuel, you just made a black hole.

You are right. But we would disagree on the fuel requirement thing.

 

[Persol]

Yes, we would.. but it's pointless arguing that with you when you don't really understand the reason/math behind it.

 

[MacM]

Yes, we would.. but it's pointless arguing that with you when you don't really understand the reason/math behind it.

Wrong again. I understand that the math is based on your acceptance of the reality of Relativity disregarding that it involves an unjustified assumption.

 

[2inquisitive]

OK, Persol, another little thought experiment dealing with this situation. I am an alien
in my spaceship that has become lost in space. I am located between the Earth and
a Quasar that is spewing out ejecta in my direction. There is only a 2 degree difference
between the heading directly toward the Quasar and directly toward the ejecta from
the same Quasar. I am in an inertial frame and want to accelerate toward the Quasar,
which is relatively stationary to me, at a rate of 1g. The ejecta from the Quasar has
a relative velocity of .95c wrt my inertial frame. From my frame of reference, does it
take more energy to accelerate to 1g, measured by my on-board instrument, toward the ejecta than it does toward the Quasar? From the Earth's frame of reference, the
Quasar and my ship are receeding at .95c and the ejecta has no relative velocity. From
the Earth's FOR, are there any differences in energy requirements for my 1g acceleration toward either object?

 

[Persol]

From my frame of reference, does it take more energy to accelerate to 1g

No.

are there any differences in energy requirements for my 1g acceleration toward either object

No, but the work done is frame dependent.

 

[2inquisitive]

So I don't have to worry about being crushed by the gravity of the additional fuel
requirements because there are none in my frane of reference? I don't have to worry
about turning into a black hole IN MY FRAME OF REFERENCE. This whole infinite energy
thing is only from the Earth's frame of reference? (or from the frame of reference of
any observer that has a great relative velocity to me)

 

[Persol]

If you want to get to .95c then it is with respect to something. You'll never get above 0c in reference to your ship.

Reaching .95c relative to something else WOULD require alot of fuel.

 

[2inquisitive]

Yes, but in my reference frame, the fuel requirement to accelerate from an inertial
frame to 1g by my instruments would be the same. The relative velocity between
myself and any outside frame of reference would make no difference. I could choose
any other frame of reference I want, and the fuel requirements would be the same amount for my acceleration.
High relative velocity wrt any other frame would have no effect.

 

[Persol]

Yes, but in my reference frame, the fuel requirement to accelerate from an inertial frame to 1g by my instruments would be the same.

you are missing the point. You have no idea what your initial velocity is, so you have no way of saying when you are going .95c.

the fuel requirements would be the same amount for my acceleration.

Be careful here. Your measured g force is not neccessarily your acceleration.

High relative velocity wrt any other frame would have no effect.

On your g force, no.. it wouldn't. On your distance travelled and externally calculated acceleration, it would.

 

[GMontag]

Don't let the test throw you a curve. It has been done in this manner simply because members here would never agree on a method of synchronizing clocks to perform the test of time dilation affects of relative velocity according to Relativity.

By assuming Relativity valid and using the timers was to insure they stopped simultaneously, according to Relativity. It is nothing more than a means of comparing numbers and of course makes no actual test.

Mac, this is the point that you don't seem to be getting. Simultaneity is frame dependant. There is no such thing as "simultaneous in reality". Depending on what reference frame you are using, simultaneaity changes. This is not an illusion.

Now the oint was that according to "A" when it reaches 36,000 seconds, B would has slowed down and only be 15,692 seconds. Further according to B A slowed down such that after 15,692 seconds at B's local time "A" would have only accumulated 6,840 seconds. Stopping the clocks simultaneouls according to Relativity shows that this is not the case "A" actually reads 36,000 seconds, not B's viw of "A" of 6,840 seconds. Hence B's view is NOT physical reality, it is only an illusion of motion, a perception and not actual time dilation.

Again, let me reiterate, using the timers ensures simultaneity in A's frame only. There is absolutely no reason why the clocks should stop simultaneously in B's frame as well. If you want to, you can program the timers so that they will stop simultaneously in B's frame (i.e. B's clock stops at 36,000 ticks and A's clock stops at 15,692 ticks). Then B will see the clocks stop simultaneously, and A won't. There is no possible way in this test to program the timers so that the clocks will stop simultaneously in both frames.

 

[Persol]

There is no possible way in this test to program the timers so that the clocks will stop simultaneously in both frames.

Just to avoid the obvious... 'unless relativity is wrong'.

This though experiment proves nothing in itself.... although MacM seems to have been pushing it as a reason relativity is wrong.

 

[MacM]

Mac, this is the point that you don't seem to be getting. Simultaneity is frame dependant. There is no such thing as "simultaneous in reality". Depending on what reference frame you are using, simultaneaity changes. This is not an illusion.

Again, let me reiterate, using the timers ensures simultaneity in A's frame only. There is absolutely no reason why the clocks should stop simultaneously in B's frame as well. If you want to, you can program the timers so that they will stop simultaneously in B's frame (i.e. B's clock stops at 36,000 ticks and A's clock stops at 15,692 ticks). Then B will see the clocks stop simultaneously, and A won't. There is no possible way in this test to program the timers so that the clocks will stop simultaneously in both frames.

You seem to misunderstand my position. I fully agree with everything you just said.

You (and others) however, seem to miss the point that the fact that B doesn't see "A" stop has no bearing on the clocks real accumulated time.

Clocks stopped simultaneously in "A's" frame record the respective actual accumulated times and those recorded times do not reflect B's view. The fact that B sees "A" continueing to run does not translate into a physical time change for clock "A". B NEVER sees "A" continue to run and accumulate time beyond that which it had accumulated before it stopped.

The test was to determine if time dilation is perception or reality. The test is to see clock readings per time dilation predictions of all observers. When B's clock stopped the test was over and his monitor of A's clock stopped and displays what the "A" clock should read per it being slower and his stopped clock with the accumulated time of 15,692 seconds. "B" says that "A" should read 6,840 seconds but "A" actually at that instant reads 36,000 seconds but B sees "A" continue to run but upto and only its true stopped time of 36,000 seconds and his view of 6,840 seconds is shown to not be physical reality.

It is the reality vs perception that is at issue and not simultaneity.

 

[Persol]

You (and others) however, seem to miss the point that the fact that B doesn't see a stop has no bearing on the clocks real accumulated time.

So you say, but you have nothing to back that up besides a belief that relativity is false.

We all agree that you are right if time is not relative... do you actually have a point beyond that?

It is the reality vs perception that is at issue and not simultaneity.

They are the same issue.

 

[2inquisitive]

"you are missing the point. You have no idea what your initial velocity is, so you have no way of saying when you are going .95c"
=============================================================

I guess that is the point. .95c is a relative value, the relative velocity between an
observer and another frame of reference. Choosing one reference point over another
does not change the observer's mass or increase his resistance to acceleration, at
least the way I see it. Of course the increase in relative velocity will differ
greatly according to which reference point the observer chooses.

quote:
"On your g force, no.. it wouldn't. On your distance travelled and externally calculated acceleration, it would."
===========================================================

SR's calculations of mass and fuel requirements are calculated from an external
frame of reference, the Earth usually. That is why I chose an alien from an unknown
location, so the lorentz transforms couldn't collapse everything to Earth's frame of
reference.

 

[Persol]

Choosing one reference point over another
does not change the observer's mass or increase his resistance to acceleration, at
least the way I see it.

More specifically.... the way the observer sees it

SR's calculations of mass and fuel requirements are calculated from an external
frame of reference, the Earth usually.

Yeah, if you aren't concerned with your position/time compared to another reference frame than reativity isn't needed... but just because you feel 1g doesn't mean that is your acceleration realtive to an outside point, and it's therefore not a valid way of computing your velocity.

 

[2inquisitive]

NO, I would compute my relative velocity by the Doppler shift of the light comming
from my chosen point of reference, for instance the Quasar that initially had zero
relative velocity to me, or the light from the Quasar ejecta that was already blue-shifted in my initial inertial frame.
But, maybe you are right and that is how I got lost in the first place!

 

[MacM]

Just to avoid the obvious... 'unless relativity is wrong'.

This though experiment proves nothing in itself.... although MacM seems to have been pushing it as a reason relativity is wrong.

It is simply amazing that you can say what you say.

The test does not claim the clocks stopp simultaneously in both frames.

But stopping in "A's" frame shows that "B's view is not reality. It is perception only. The only reality it the times accumulated on the clocks.

So it isn't that Relativity is so wrong as it is that you (and others) are wrong to claim Relativity is physical reality. It is clear with no room for reasonable doubt that Relativity is perception only.