14
   

Why in the world would Einstein suggest....

 
 
layman
 
  -1  
Reply Thu 19 Feb, 2015 03:00 pm
@parados,
Got interrupted on that last post--ignore it. It's too late to edit it now.

You say:
Quote:
When accelerating, the time at the ceiling will move at a different rate than the time at the floor, all part of the non inertial state.


I'm not even sure what your point is, but you have left out a critical part of the excerpt you cut and pasted, to wit:

Quote:
(1) an observer stationed on the ceiling measures the light on the ceiling to be travelling with speed c, (2) an observer stationed on the floor measures the light on the floor to be travelling at c, but (3) within the bounds of how well the speed can be defined (discussed below, in the General Relativity section), a "global" observer can say that ceiling light does travel faster than floor light.


Note 3--a "global observer will say that one "is correct."

The whole premise here is that BOTH gravitational (GR) and speed (SR) dilation are being considered together. Unlike speed dilation, gravitational dilation is NOT relative. It is absolute.

But it is also separate from, and completely independent of, speed dilation (SR). He is saying one observer is "near the ceiling" precisely so that the GR effect can be eliminated.
0 Replies
 
layman
 
  -1  
Reply Thu 19 Feb, 2015 03:04 pm
@parados,
Quote:
The Minkowski diagram would show how it plays that part.
A minkowski diagram "shows" nothing with respect to the PHYSICS involved--only the math, as Einstein himself said. I just quoted him (and could quote more) but here it is again:

Quote:
"Geometry predicates nothing about relations of real things, but only geometry together with the purport of physical laws can do so... The idea of the measuring rod and the idea of the clock coordinated with it in the theory of relativity do not find their exact correspondence in the real world." (Einstein, 1921)


A minkowski diagram can show lines on a piece of graph paper, but that piece of graph does not, and can not, cause time dilation. Nor can it "explain" time dilation in any physical sense. It can only give you the result of applying math

Once again: Al: "Geometry predicates nothing about relations of real things..."
parados
 
  3  
Reply Thu 19 Feb, 2015 03:14 pm
@layman,
Are you arguing that the math is wrong?
layman
 
  -1  
Reply Thu 19 Feb, 2015 03:17 pm
@parados,
Quote:
Are you arguing that the math is wrong?


No. Not at all.

The math is entirely correct. But it is what it is, i.e., math. It is not physics.
parados
 
  3  
Reply Thu 19 Feb, 2015 03:22 pm
@layman,
The math predicts that clocks traveling at a faster speed will slow down. The physics confirms the math.
layman
 
  -1  
Reply Thu 19 Feb, 2015 03:27 pm
@parados,
Quote:
The Minkowski diagram would show how it plays that part.


Einstein himself pointed out that the exact same 1 hour (or one day) turn-around could give a "mathematical" difference of 1 year, 100 years, 1000 years, 1,000,000 years, one billion years, etc., all depending on the length of the flight prior to turn-around.

For that reason, he immediately rejected the turn-around as in any way causing or explaining the time dilation involved.
0 Replies
 
layman
 
  -1  
Reply Thu 19 Feb, 2015 03:29 pm
@parados,
Quote:
The math predicts that clocks traveling at a faster speed will slow down. The physics confirms the math


No. "Math" doesn't make the predictions. The physical theory does that. Math attempts to implement, in representational form, the presumptions of the physical theory. It doesn't (and can't) "confirm" anything.

You have it completely backwards.
parados
 
  2  
Reply Thu 19 Feb, 2015 03:41 pm
@layman,
That's an interesting argument layman. So, you are arguing that before Einstein published his theory of relativity we already knew that clocks slowed down when they moved faster. Care to point me to that physics from the late 1800s or early 1900s?
layman
 
  -1  
Reply Thu 19 Feb, 2015 03:50 pm
@parados,
Quote:
So, you are arguing that before Einstein published his theory of relativity we already knew that clocks slowed down when they moved faster.


Yeah, Lorentz formulated the math, about 15 years before Al used it in his theory. But again, the math didn't jump up, from out of nowhere, and tell anybody anything. Math doesn't talk, or predict.

The math was developed to put the predictions in a precise form.

The Lorentz equations "say" the moving clock will slow down. Because that's what the theory predicts. But the equations do not, and cannot, tell you which one (as between a clock on a moving train and one on the ground) will run slower (i.e., which one is moving faster).

Ultimately, empirical experiment has to make that determination. In the case of time dilation, it has been shown that the train clock slows down, not the earth clock. Therefore, it is the train clock which is (or was) moving. As if we didn't already know....
0 Replies
 
layman
 
  -1  
Reply Thu 19 Feb, 2015 04:31 pm
@parados,
Quote:
... So, you are arguing that before Einstein published his theory of relativity we already knew that clocks slowed down when they moved faster.


To be precise, we didn't "know" anything. But it had long been "theorized" that clocks would slow down. It wasn't until relatively recently that our clocks became accurate enough to actually measure the difference.
0 Replies
 
layman
 
  -1  
Reply Thu 19 Feb, 2015 04:49 pm
@parados,
Quote:
Both would see the other clock as moving slower. Both would be correct.


Well, there you go, Parados. Now you are creating the "paradox." But it aint a paradox, it's merely a flat contradiction.

No physicist (or any other sensible person) contends that "each is correct" in an objective sense. It's impossible for each clock to be running slower than the other.
parados
 
  3  
Reply Thu 19 Feb, 2015 05:59 pm
@layman,
Quote:

Well, there you go, Parados. Now you are creating the "paradox." But it aint a paradox, it's merely a flat contradiction.

No, it isn't a paradox. They are different frames of reference. You just can't seem to understand the concept.

Quote:
It's impossible for each clock to be running slower than the other.
Why do you think that is so? Is it because you are insisting on only using one frame of reference? That kind of defeats the entire point of SR and GR.
layman
 
  -1  
Reply Thu 19 Feb, 2015 06:03 pm
@parados,
Quote:
No, it isn't a paradox. They are different frames of reference.


You could have 10 million frames of reference. And each and every one of those 10 million could "claim" (assume, or argue) that THEY were motionless. But, as a logical matter, ONLY ONE could possibly be objectively correct when making this claim. ALL of them could be wrong, but no more than one could possibly be right (assuming they were all moving with respect to each other).

I asked two different kids what 5 & 3 was the other day. They gave me different answers. Each one thought HE was right. Sure, they can both think that. But CAN they both be right? Of course not.

Turns out they were both wrong (one said 7, the other said 9).
layman
 
  -1  
Reply Thu 19 Feb, 2015 06:18 pm
@parados,
I'm starting to get a better feel for what this Hayes guy (who I quoted earlier) was saying:

Quote:
[Hayes says]: "Precisely because Einstein's theory is inconsistent, its supporters have drawn on contradictory principles in a way that greatly expanded their apparent ability to explain the universe. Most crazes die out when it becomes obvious that they were overblown. The amazing thing about Einstein's theory of relativity is that it has kept going. It is built on contradictions, but these very contradictions means that almost anything ‘proves' that it is right. It is a bit like a theory where you say 1 + 1 = 2, but also that 1+ 1 = 3."
0 Replies
 
parados
 
  3  
Reply Thu 19 Feb, 2015 06:19 pm
@layman,
Quote:
In Einstein's theory, there is a definition of simultaneity that employs light signals going back and forth (cf. The definition of "now"). However, simultaneity thus defined is relative. Observers that are in motion relative to each other (and that employ Einstein's definition of simultaneity) will generally end up with different results: events that one observer judges to be simultaneous will not necessarily be simultaneous for the other.

This insight allows relativity to escape the apparent contradiction that one and the same clock is both slower and faster than another clock. When I come to the conclusion that the clocks in the other space-station are slower, I rely on my own concept of simultaneity for the comparison. The other observer, coming to the conclusion that my clocks run slower, relies on his own concept of simultaneity. (A simple geometric analogy to this is explored in the spotlight topic Time dilation on the road.)

http://www.einstein-online.info/spotlights/dialectic



Quote:
Hold on, I hear you say, how can both clocks run slow? Surely that's impossible? Puzzling, but not impossible. Let's suppose that they synchronise clocks when they pass each other. What happens when they compare time later? Now remember that their relative speed is a substantial fraction of the speed of light. Consequently, when Zoe looks at Jasper's clock, the light will take a while to reach her eyes. So she will see the time that the clock read when the light that she is seeing reflected off Jasper's clock. (Think of astronomers looking at very distant galaxies: they emitted the light we see when they and the universe was much younger than it is now.) So distant observes can't just use the time that they see on the clock, they have to correct this for the time of transmission of light (or radio etc) that is used to send the local time.

This synchronisation effect is important enough to need another page on its own, because it is tempting to try to use this symmetry to create a paradox that would disprove relativity. See the twin paradox for an explanation.

http://newt.phys.unsw.edu.au/einsteinlight/jw/module4_time_dilation.htm

Quote:
Since that procedure yields different judgments of simultaneity for different frames of reference, there is no longer an absolute fact as to whether two events are simultaneous; that judgment can vary from frame to frame.

http://www.pitt.edu/~jdnorton/Goodies/rel_of_sim/




http://www.sparknotes.com/physics/specialrelativity/kinematics/section2.rhtml
parados
 
  3  
Reply Thu 19 Feb, 2015 06:26 pm
@layman,
Quote:
ONLY ONE could possibly be objectively correct when making this claim.

There is no objective reference. There is only a relative reference. Both are correct within their own reference.

Assume a sound is being played over a speaker at a pitch of middle C. There are two observers listening to that speaker. One is moving toward the speaker and one is moving away from the speaker. They each hear a pitch different than middle C because of the Doppler effect. They are clearly hearing a sound. You are arguing they are hearing an incorrect sound. They just have a different reference compared to the speaker. It doesn't make their sound wrong.
layman
 
  -1  
Reply Thu 19 Feb, 2015 06:42 pm
@parados,
Quote:
Now remember that their relative speed is a substantial fraction of the speed of light. Consequently, when Zoe looks at Jasper's clock, the light will take a while to reach her eyes. So she will see the time that the clock read when the light that she is seeing reflected off Jasper's clock.


You fall for this kind of sophistry, Parados? All physicists agree that the inherent delay caused by the time it takes light to travel has NOTHING to do with time dilation. That is always factored out before determining the amount of dilation. It is a non sequitur.
0 Replies
 
layman
 
  -1  
Reply Thu 19 Feb, 2015 06:51 pm
@parados,
Quote:
In Einstein's theory, there is a definition of simultaneity that...


Yes, indeed, there is such a "definition." You can define things any way you want, so what? Einstein never even tried to claim it was the "right" definition. On the contrary, he stressed that he was just giving a definition of his own choosing---not something that could be proved right or wrong.

Quote:
Since that procedure yields different judgments of simultaneity for different frames of reference, there is no longer an absolute fact as to whether two events are simultaneous; that judgment can vary from frame to frame.


Correct BY that definition. It is not a definition that is required. Al uses mere (dubious) assumptions (such as that a guy on a train is "correct" when he claims he's not moving relative to the earth) to establish a concept of simultaneity that is "relative."

Theories which define simultaneity as absolute work just as well as (and better in many cases) than SR. They "define" simultaneity differently.

Your definition does not, and cannot, prove your assumption (in the case of either theory).
layman
 
  -1  
Reply Thu 19 Feb, 2015 07:01 pm
@parados,
Quote:
each hear a pitch different than middle C because of the Doppler effect. They are clearly hearing a sound. You are arguing they are hearing an incorrect sound. They just have a different reference compared to the speaker. It doesn't make their sound wrong.


Parados, I have responded to this type of claim repeatedly in this thread. It gets wearisome. I assume that you have not read much said in the thread before you got involved. This post sited below, and the several following it, are just a few of the one's I'm referring to.

http://able2know.org/topic/265997-3#post-5875171
layman
 
  -1  
Reply Thu 19 Feb, 2015 07:10 pm
@parados,
I will take the time to repeat one prior post in it's entirety here (from page 7 of this thread):

An analogy similar to Al's "passenger on a train who insists he's motionless" explanation of "relative simultaneity" can be seen in a lightning vs thunder scenario.

A guy who is right next to a lightning-struck cloud will both see the lightning and hear the thunderclap simultaneously.

On the other hand, a guy a few miles away will see the lightning, but not hear the thunder for maybe 10 to 15 seconds later.

Do physicists then say that the thunder was generated at two distinct times because subjective observers heard the thunder at different times? Of course not.

They simply explain why the second observer heard the thunder later. They do NOT say that he is "correct" when he claims the lightning and thunder were "not simultaneous."
 

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