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> Another Time Dilation Paradox, Dilation physically tied to no dilation.
photo_guy
Posted: Mar 3 2012, 01:27 AM


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QUOTE (Robittybob1 @ Mar 2 2012, 07:36 PM)
The difference I see is the satellite is affected by the two opposing effects: gravity and velocity.  Whereas the disk is only affected by velocity.  So one is time dilated but the other is at the point in space where the two cancel each other out.


The satellite is affected by all three... Mass, centrifugal and inertia... Mass and centrifugal cancel each other out so the sat can stay in freefall orbit.

It's the inertial gravity that's slowing their clock down. Although I don't rule out the possibility that both mass and centrifugal both play a part too... I strongly suspect they do. They balance each other out as far as keeping the sat in orbit but that's not necessarily saying they don'e affect the sat clocks's time keeping ability to some extent too...

They may be like two cars chained to something in the middle and pulling in opposite directions. The thing in the middle isn't moving either way but it would certainly be under some stress....


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Robittybob1
Posted: Mar 3 2012, 01:53 AM


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QUOTE (photo_guy @ Mar 3 2012, 01:27 AM)

The satellite is affected by all three...  Mass, centrifugal and inertia...  Mass and centrifugal cancel each other out so the sat can stay in free fall orbit. 

It's the inertial gravity that's slowing their clock down.  Although I don't rule out the possibility that both mass and centrifugal both play a part too...  I strongly suspect they do.  They balance each other out as far as keeping the sat in orbit but that's not necessarily saying they done affect the sat clock's  time keeping ability to some extent too... 

They may be like two cars chained to something in the middle and pulling in opposite directions.  The thing in the middle isn't moving either way but it would certainly be under some stress....

Satellites are held in their orbits at many different heights and the closer to the Earth they are the faster they are orbiting. So if relativity is correct the Space Station might be a place to confirm that there is time dilation.

But I feel you still haven't understood that the higher the orbit the slower the satellite moves, so the time dilation due to velocity declines the higher you go. But the other time-speeding-up effect of lower gravity is increased the further from the Earth you go so there is a point where the two opposing effects balance.
What height does that happen?

This post has been edited by Robittybob1 on Mar 3 2012, 01:55 AM
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photo_guy
Posted: Mar 3 2012, 11:05 AM


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QUOTE (Robittybob1 @ Mar 3 2012, 01:53 AM)
Satellites are held in their orbits at many different heights and the closer to the Earth they are the faster they are orbiting.  So if relativity is correct the Space Station might be a place to confirm that there is time dilation.

But I feel you still haven't understood that the higher the orbit the slower the satellite moves, so the time dilation due to velocity declines the higher you go.  But the other time-speeding-up effect of lower gravity is increased the further from the Earth you go so there is a point where the two opposing effects balance. 
What height does that happen?


I understand satellites fairly well.. I worked at Western Union's Glenwood Earth Station for a while in the late 70's. At one time there were 7 Westars up at once.

So I've always been thinking geo-sync orbits... 24 k miles up where mass and centrifugal nutralize each other and the sat has enough inertia to keep it in free fall orbit.

So inerta is what is slowing the clocks. Although I suspect mass and centrifugal still play a part... They may balance as far as keeping the sat in orbit but I'm sure they're affecting the clock's atoms to do that. Like two cars tied to something in the middle and pulling in opposite directions. The something wouldn't be moving but it would certainly be under stress.

In any case, I never got into the physics end of it at the time so I don't know if there was a relative time slowing. I don't remember any being mentioned... The only delay I knew about was up and down transmission times.

So as for your question at what height 'speed up' from height and 'slow down' from velocity washes.., it's still a question. 24 k miles up may very well be where it happens. When all three are in sync to keep the sat in one place above the earth. ?

But right now, to me, it's only just a possible. And only possible because it IS a balance point that's locked to the earth's rotation. And you don't need a ladder on a mountain top to be there.

Cause with sats at least.., their velocity is going to be what's needed to keep the mass and cf balanced. If you went real close to earth and didn't have that mountain top to put a ladder on.., a sats velocity would be too intense to get a meaningful measurement.

It certainly wouldn't be in geo sync, which I believe is what your question ultimately requires...



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Remembering my mother... Margaret McGough. Died 1948
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Robittybob1
Posted: Mar 3 2012, 04:56 PM


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That is right - the GPS satellites do have clocks which are slowed and the problem must only get worse as you come in closer. For your velocity rises and the G force increases as the radius is shorter.
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Guiri
Posted: May 3 2012, 10:39 PM


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I just love reading about GPS and Relativity,

Time Dilation is pure fantasy.

Here's an easy question for the logically challenged.
Read the second section of Einsteins paper (1905) Electrodynamics of moving bodies.

tB-tA and t'A-tb = Time taken for the rod travelling between A and B
c-v and c+v = Velocities of the rod travelling between A and B
rAB = Length of the Rod (not distance travelled)

What is the length of the rod at rest and at velocity c?

Velocity of rod at rest is 0, therefore rAB = 0
Velocity of rod at c is c, therefore rAB = 2c

This means the rod at rest is zero length and if it travels at c then it is twice the length it has actually travelled,

Does something look wrong?
[Moderator: Your abuse of math and physical assumptions looks wrong. A rod cannot travel between locations at well-defined times because one end arrives before the other. There are other problems and a lack of clear explanation. For a better introduction to length contraction, you are required to go read and understand this post before making any assertions in physics. The penalty for not fully understanding this post before continuing will be a complete loss of faith in your good intentions by the moderator.]

This post has been edited by rpenner on May 4 2012, 02:51 PM
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Guiri
Posted: May 5 2012, 12:04 AM


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QUOTE (Guiri @ May 3 2012, 10:39 PM)
I just love reading about GPS and Relativity,

Time Dilation is pure fantasy.

Here's an easy question for the logically challenged.
Read the second section of Einsteins paper (1905) Electrodynamics of moving bodies.

tB-tA and t'A-tb = Time taken for the rod travelling between A and B
c-v and c+v = Velocities of the rod travelling between A and B
rAB = Length of the Rod (not distance travelled)

What is the length of the rod at rest and at velocity c?

Velocity of rod at rest is 0, therefore rAB = 0
Velocity of rod at c is c, therefore rAB = 2c

This means the rod at rest is zero length and if it travels at c then it is twice the length it has actually travelled,

Does something look wrong?
[Moderator: Your abuse of math and physical assumptions looks wrong. A rod cannot travel between locations at well-defined times because one end arrives before the other. There are other problems and a lack of clear explanation. For a better introduction to length contraction, you are required to go read and understand this post before making any assertions in physics. The penalty for not fully understanding this post before continuing will be a complete loss of faith in your good intentions by the moderator.]

Thank you for your comment moderator,

I make no assumptions nor abuse maths, they are Einstein's straight out of his 1905 paper.

"where rAB denotes the length of the moving rod—measured in the stationary system" (not the length).

First equation
Stationary rod at origin of x-axis v = 0 and t = 0
rAB = (tB-tA).(c-v)

tB-tA = 0 rod has not moved
and c-0 = c velocity is zero

rAB = (0).(c-0) = 0

Length of rod is zero

Second equation
rAB = (t'A - tB).(c+v)

v = c
t'A - tB = assume 1 second

rAB = 1.c+c = 2c

Alternatively

tB = d/c and t'A = 2(d/c)
d/c(2c) = 2d

rAB = 2d.2c

the math is simple
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