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Posted

The time for light to travel back to Bob from that transition point would establish how long Alice would age at 2c which would give a total time Alice has aged more than Bob once she hits the event horizon at c and blows up the entire universe in the process. 

 

 

 

To kinda paraphrase good ole Winston:  "Never have so many words been used to convey so little meaning to so few."

 

Posted (edited)

Ah, somebody worth talking to.

 

My understanding is that the observer outside the black hole would see you, falling into the hole, eventually stop at the event horizon, your clock frozen, and then see you red-shift out of the visible spectrum.

Not quite. A distant observer never sees the falling observer reaching the event horizon. They see time dilation, length contraction and red shift of the observer continually increasing and approaching would what be infinite time dilation, length contraction and red shift at the horizon but the object is never frozen in time, contracted to no length or infinitely redshifted.

The important point here is that from the perspective of the distant observer, the falling object can always accelerate away from the black hole. Now can the falling observer can reach the event horizon in their own accelerated frame? It is true that they do reach the event horizon at a specific time on their own watch and of course time is progressing normally from their perspective.

The problem is the amount of time that passes on the watch of the distant observer from the frame of the falling observer before they reach the horizon. If it's a finite amount of time then this contradicts the fact in the frame of the distant observer the falling observer can still accelerate away from the black hole after the distant observer's watch passes this time.

The only conclusion is that an infinite amount of time has to pass on the watch of the distant observer before the falling observer reaches the horizon, from not only the frame of the distant observer but also in the frame of the falling observer so it's something that never happens in either frame. Although there is a time on the watch of the falling observer when they would reach the event horizon, it's a time that is never reached.

~And to link it to the second question.~

If the distant observer were to move towards the black hole then the falling observer will still never be able to reach the event horizon in front of them because if they did then they would have to reemerge from inside the horizon if the more distant observer were to move away again.

Also it well and truly shatters the time reversible aspect of gravity because again, an object would have to reemerge from inside the event horizon, this time if the arrow of time is reversed.

 

The falling person would — depending on how quickly she was approaching the event horizon — see the future history of the universe unfold, but not all of it before she crossed the horizon.

It would have to be the entire future history of the universe and that still wouldn't be enough time, no amount of time is enough. If there was a time when the falling observer reaches the horizon, say when the light from a distant supernova reaches the two observers then after this time it would be impossible for the falling observer to move away from the black hole but this would contradict the Schwarzschild coordinate system showing that from the frame of a distant observer it's always possible for them to accelerate away.

 

Thanks, I'll check that out.

Edited by A-wal
Posted

Someone who thinks he changes the nature and relationship of objects in the entire universe every time he writes the words "from the perspective of" might have some slight delusions of grandeur, know what I'm sayin?

Posted

In your case mediocrity would be a delusion. If you understood any of this you'd know that my arguments are actually based on the fact that frame independent events can't be changed by switching perspectives.

Posted (edited)

In your case mediocrity would be a delusion. If you understood any of this you'd know that my arguments are actually based on the fact that frame independent events can't be changed by switching perspectives.

 

 

Virtually every frame in the universe is accelerating, so they're all frame independent for that reason alone.   Of course so are inertial frames, which you deny, but there aren't any, so in that sense the point is moot.

 

But that aint the point, and it aint moot as a matter of common sense. It is ridiculous to assert that any mere "change of frame" can reverse which of two or more objects are actually moving (faster).  Reciprocal time dilation is impossible, for example.  Assuming that the earth is stationary does not, and cannot, force it to cease its revolutions around the sun.

 

Having an infinite number of observers in inertial motion "see" the earth going at an infinite number of different speeds, etc., doesn't affect the earth at all.  It just keeps on chugging along, at its regular rate of speed, as always.

Edited by Moronium
Posted (edited)

One thing that you don't seem to understand is what "relative," or for that matter, what "absolute" motion even is, Awol  You think that if you need to say that an object's motion is "relative to" something in order to give context to the word "motion" then that means that its motion is now relative.

 

Wrong.  Even absolute motion is always "relative to" something. (i.e. a preferred frame).

 

As a purely theoretical matter, all you have to do is establish, however arbitrarily, a preferred frame in order to make all motion absolute.

 

The preferred frame could be your girlfriend's treehouse.  That wouldn't change the concept at all.  But from there on, you would never ask how fast the sun is going relative to mars or any other such questions.  That would be irrelevant.  The only question would be how fast each is going relative to your girlfriend's treehouse, and that speed, whatever it is, would be an absolute speed, theoretically.  It would be frame independent.  Mars would agree with the established absolute speed of the sun, and the sun would agree about the absolute speed of Mars.  How they "saw each other" would be irrelevant.

 

NOTE: I am NOT saying that your girlfriend's treehouse in an appropriate choice to serve as a preferred frame.  I'm just explaining the concept of absolute motion as a strictly theoretical matter.

 

Do you continue to erroneously maintain that the GPS does not employ a PFT rather than SR, by the way?

Edited by Moronium
Posted (edited)

 that speed, whatever it is, would be an absolute speed, theoretically.  It would be frame independent.  Mars would agree with the established absolute speed of the sun, and the sun would agree about the absolute speed of Mars.  How they "saw each other" would be irrelevant.

 

To illustrate:  Let's say you have three objects, like this:   A<-------E-------->B

 

E is the earth, and you elect to treat it as a preferred frame.  A and B are each moving away from E at equal speeds of .4c, OK?  Employing a PFT, the earth's speed would be seen by all parties to be zero.

 

A and B would both see their own speed as being .4c, and each would calculate that, since they are going the same speed (relative to earth), then there is no time dilation as between them. Their respective clocks will be ticking at the same rate. This is notwithstanding that they are separating from each other at the relative rate of .8c. 

 

.4c is their absolute speed; .8c is merely their (irrelevant) relative speed.  A and B would both consider their own clocks to be slower than the earth's, and the earth would see it the same way (its clock would be faster).

 

I wonder if you're even capable of understanding that.

 

If you prefer to hear it in symbolic form, it's very simple, to wit:  t = t'  Time, like motion, is absolute, not relative.  Of course, relative to the earth, A and B's clocks would both slow down, and their lengths would contract.

 

And, for that reason, A and B would each measure the speed of light to be c in their own frames IF they relied on the instruments available to them and IF they ignored their own motion.

Edited by Moronium
Posted (edited)

Do you continue to erroneously maintain that the GPS does not employ a PFT rather than SR, by the way?

 

 

For the benefit of any one who cares to know the correct answer to this question, I will repaste this post from another thread:

 

Posted 05 March 2019 - 01:24 PM

 

Ashby is widely recognized as an expert regarding the GPS.  This paper tells you more than you'd ever want to know about the GPS and how it works, and has lots of math for those who love math.  I'm just quoting pertinent excerpts.

 

Relativity in the Global Positioning System

 

Neil Ashby, Living Reviews in Relativity December 2003, 6:1

 

The Global Positioning System (GPS) uses accurate, stable atomic clocks in satellites and on the ground to provide world-wide position and time determination. These clocks have gravitational and motional frequency shifts which are so large that, without carefully accounting for numerous relativistic effects, the system would not work.

 

The purpose of this article is to explain how relativistic effects are accounted for in the GPS. Although clock velocities are small and gravitational fields are weak near the earth, they give rise to significant relativistic effects. These effects include first- and second-order Doppler frequency shifts of clocks due to their relative motion, gravitational frequency shifts, and the Sagnac effect due to earth’s rotation. If such effects are not accounted for properly, unacceptably large errors in GPS navigation and time transfer will result.

 

Almost all users of GPS are at fixed locations on the rotating earth, or else are moving very slowly over earth’s surface. This led to an early design decision to broadcast the satellite ephemerides in a model earth-centered, earth-fixed, reference frame (ECEF frame), in which the model earth rotates about a fixed axis with a defined rotation rate...

 

Although the ECEF frame is of primary interest for navigation, many physical processes (such as electromagnetic wave propagation) are simpler to describe in an inertial reference frame. Certainly, inertial reference frames are needed to express Eqs. (1), whereas it would lead to serious error to assert Eqs. (1) in the ECEF frame.

 

The time transformation t = t′ in Eqs. (3) is deceivingly simple. It means that in the rotating frame the time variable t′ is really determined in the underlying inertial frame. It is an example of coordinate time.

 

Now consider a process in which observers in the rotating frame attempt to use Einstein synchronization to establish a network of synchronized clocks...Observers fixed on the earth, who were unaware of earth rotation, would use just ƒ dσ′/c for synchronizing their clock network. Observers at rest in the underlying inertial frame would say that this leads to significant path-dependent inconsistencies, which are proportional to the projected area encompassed by the path.

 

Synchronization is thus performed in the underlying inertial frame in which self-consistency can be achieved.... For atomic clocks in satellites, it is most convenient to consider the motions as they would be observed in the Earth-Centered Inertial (ECI) Frame.  Then the Sagnac effect becomes irrelevant...For the GPS it means that synchronization of the entire system of ground-based and orbiting atomic clocks is performed in the local inertial frame, or ECI coordinate system.

 

 

 

https://link.springer.com/article/10.12942/lrr-2003-1

 

Anyone who understands that, and who also understands the basic premises of SR (who I've yet to run across in this forum) would immediately understand that the GPS system rejects SR and adopts a Preferred Frame Theory of relativistic motion, with the ECI serving as the preferred frame.

 

SR simply will not work in the "real world."

 

A PFT treats all motion, simultaneity, and time as absolute, not relative.  It has to, for the GPS to be a viable practical system.  Although SR cannot be used, the Lorentz transformations can and are, of course.  The GPS abandons SR's formulation of the LR, and implements them in the way Lorentz designed them. This of course means that the speed of light is not constant in every inertial frame.  The speed of light is variable in GR, too, of course.

Edited by Moronium
Posted (edited)

 

The conclusion of your link does not agree with the emboldened statement

 

 

14 Conclusions

The GPS is a remarkable laboratory for applications of the concepts of special and general relativity. GPS is also valuable as an outstanding source of pedagogical examples. It is deserving of more scrutiny from relativity experts.

Alternative global navigation systems such as GLONASS, GALILEO, and BEIDOU are all based on concepts of clock synchronization based on a locally inertial reference system freely falling along with the earth. This concept, fundamentally dependent on a relativistic view of space and time, appears to have been amply confirmed by the success of GPS.

Plans are being made to put laser-cooled clock(s) having stabilities of 5×1014/τ5×10−14/τ and accuracies of 1 × 1016, on the International Space Station. This will open up additional possibilities for testing relativity as well as for making improvements in GPS and in other potential navigational satellite systems.

 

 

 

The "concepts" of SR include time dilation, incorporation of the mathematical formulations of the LT, etc. but those are not SR.  I don't know why so many people don't seem to understand this.

 

GR is not a theory of relative motion and has nothing to do with SR.  Einstein himself said as much later in his career, as have many other physicists.

 

SR uses, exclusively, Newton's definition of an "inertial frame" not that later proposed by GR.  In short, GR really has nothing directly to do with SR, which is the topic at hand.

 

Whatever the author said in this one sentence does not change the contents of the entire paper, however subject to misinterpretation that one sentence  might be to some.

 

The paper itself supports only one possible conclusion, to wit:  Insofar as dealing with the velocity (not gravitational) time distortions go, the GPS engineers have rejected SR and relied on a preferred frame theory.

 

The part you quote even goes so far as to point out that all alternative systems do the same:  "Alternative global navigation systems such as GLONASS, GALILEO, and BEIDOU are all based on concepts of clock synchronization based on a locally inertial reference system freely falling along with the earth."  They all synchronize clocks with a preferred frame, and "einstein synchronization" is rejected.  You'll note that I have bolded the same words you did.  The bolded words support my conclusions, but undermine yours, in this case.

 

Do you deny that, Flum?

Edited by Moronium
Posted

Assuming that the earth is stationary does not, and cannot, force it to cease its revolutions around the sun.

 

 

Do you deny this, Awol?  As always, you evade giving any substantive response to any criticisms made of your religion.  Instead you run away and start your dubious thread all over again with the same title.

Posted

GPS takes into account both SR and GR.

 

SR predicts that the orbiting clocks will tick 7 microseconds per day slower than ground clocks. But GR predicts that the orbiting clocks will tick 45 microseconds per day faster than the ground clocks. When the two correct predictions are combined, it turns out that the orbiting clocks tick faster than the ground clocks by 38 microseconds per day. All of this must be, and is, compensated for by GPS; otherwise the system would cease to work in very short order.

Posted (edited)

GPS takes into account both SR and GR.

 

SR predicts that the orbiting clocks will tick 7 microseconds per day slower than ground clocks. But GR predicts that the orbiting clocks will tick 45 microseconds per day faster than the ground clocks. When the two correct predictions are combined, it turns out that the orbiting clocks tick faster than the ground clocks by 38 microseconds per day. All of this must be, and is, compensated for by GPS; otherwise the system would cease to work in very short order.

 

Yes, that's what the paper I cited said.  Is there some point to your post?

 

When the two correct predictions are combined...

 

 

The issue here relates to the BASIS for making these predictions. I.e., how does the GPS make the "correct" prediction, and why is it correct?  There's no issue or dispute about the fact that corrections are made.

Edited by Moronium
Posted (edited)
I am not going to argue with the conclusions of the paper you put forward in support of your argument.

 

 

 

Nor am I.  I am merely pointing out your misinterpretation of a conclusion.  Obviously, you don't want to address that either.  Rather than address the substance of the paper, you want to revert to, and "stand on," a semantic mistake.  I'm truly sorry to see that, Flum.  I didn't expect that from you.

Edited by Moronium
Posted (edited)

GPS engineers do not rely on a preferred frame theory. I don't think you even know what a preferred frame is. It does NOT mean, "I prefer this frame to that frame, because the color is ever so much lovelier!"

 

 

I've already explained, at some length above, what a "preferred frame" means, and I certainly didn't say it was about subjective personal preference.  What does it mean, Amp?  Do you even know?

 

Are you even capable of addressing the substantive issues?  So far you have only demonstrated your complete inability to do so, all while talking BIG with nothing to back it up.

 

In the process, however, you do prove your own lack of understanding.  Like when you say this, for example:

 

GPS engineers do not rely on a preferred frame theory

 

Edited by Moronium
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