What controls time dilation?

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Offline abacus9900

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What controls time dilation?
« on: 10/10/2010 19:49:49 »
We have been told many times that two observers, one moving at a large fraction of the speed of light in a spaceship and the other one on earth (say), will each see the other's clock as moving much more slowly than their own clock and that this is somehow tied up with the constancy of the speed of light, but why? How does light decide how quickly or slowly clocks, either mechanical or biological, run?


[MOD EDIT - PLEASE PHRASE YOUR POST TITLES AS QUESTIONS, IN LINE WITH OUR FORM POLICY. THANKS. CHRIS.]
« Last Edit: 11/10/2010 10:09:08 by chris »

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Offline JP

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Re: What controls time dilation?
« Reply #1 on: 11/10/2010 08:44:32 »
Basically, it comes from enforcing two requirements in inertial reference frames.  These are frames moving at a constant velocity, so that acceleration isn't important.
1) The speed of light is constant no matter how fast you're moving.
2) The laws of physics are the same within your own reference frame no matter how fast you're moving. 

If you assume those two are true, then it turns out that observers in different frames don't end up agreeing on time or distance measurements.

The famous example would be a train passing a station.  There are two observers here: Tony is at the back of the train, and Paula is on the platform.  When Tony and Paula are right next to each other, a flash goes off at the front of the train.  Let's say they both have special watches that have been set so that one "tick" equals the time it takes for light to go from the front of the train to back. 

Tony on the train measures that it takes 1 tick for the light to reach him.  By the time the light has reached him, he's already moved past Paula, so he knows that the light will take longer than 1 tick to reach Paula.

Meanwhile, Paula is on the platform.  Since the light originated from 1 train length in front of her and appears to her to be moving at the speed of light, it only takes 1 tick of her clock for the light to reach her.  Since Tony is further ahead of her, she deduces that the light passed Tony in under 1 tick.

So Tony observes: It took 1 tick to reach Tony, and more than 1 tick to reach Paula,
while Paula observes: It took less than 1 tick to reach Tony and more than one tick to reach Paula


This disagreement happens because of point (1)--that light appears to move at the same speed to all inertial observers, regardless of how fast they're moving.  If we didn't require that, and the light came towards tony faster than it did towards Paula (because he was moving towards it), they could both agree that it took less than 1 tick to reach Tony and 1 tick to reach Paula.  However, there's overwhelming evidence that relativity is true and that the speed of light is constant for all observers, which requires that time measurements can disagree between observers.

Once you accept that time measurements disagree between observers, then point (2) tells you that the laws of physics for each observer within their reference frame seem to work according to their personal clock.  This includes biological processes, such as aging.  According to their own points of view, Tony and Paula would appear to age normally and time would appear to flow normally for them.  But if they compared their clocks, they'd find disagreement.

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Offline abacus9900

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What controls time dilation?
« Reply #2 on: 11/10/2010 11:23:09 »
Quote

Once you accept that time measurements disagree between observers, then point (2) tells you that the laws of physics for each observer within their reference frame seem to work according to their personal clock.  This includes biological processes, such as aging.  According to their own points of view, Tony and Paula would appear to age normally and time would appear to flow normally for them.  But if they compared their clocks, they'd find disagreement.


Thank you very much for that extensive reply JP, much appreciated.

I was wondering, though, if we knew why all physical processes (such as ageing) slow down at greater speeds. I know it's because time 'slows down', but what does this really imply?

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Offline JP

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What controls time dilation?
« Reply #3 on: 12/10/2010 01:59:05 »
I think it implies that our intuitive belief that time is constant for everyone isn't true.  Different observers won't agree on the time between events, and physical processes rely on a series of events to happen, so different observers say that the processes happen faster or slower...

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Offline Bill S

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What controls time dilation?
« Reply #4 on: 16/10/2010 20:37:59 »
Hi, abacus9900, we meet again.

Quote from: JP
Since the light originated from 1 train length in front of her and appears to her to be moving at the speed of light, it only takes 1 tick of her clock for the light to reach her.  Since Tony is further ahead of her, she deduces that the light passed Tony in under 1 tick.

No problem with this, but I do run into a problem with another observer. I'll work through it.


Let’s stick with Tony and Paula, and with their special clocks, but let’s alter the ticks slightly to simplify things.  I need simplicity.  Say the light takes 2 ticks to travel from source to Tony, then, in Tony’s F of R, a further tick to reach Paula. 
Tony observes: The light takes 2 ticks to reach him, then 1 tick to reach Paula.  However, Paula’s clock registers just 2 ticks for the light to reach her.  Thus, in Tony’s F of R, Paula’s clock takes 2 ticks while his takes 3.  Paula’s is running slower.

Paula observes: The light takes 2 ticks to reach her, so it must have reached Tony in 1 tick.  Thus, in Paula’s F of R, Tony’s clock takes 1 tick while hers takes 2. Tony’s is running slower.

What does an outside observer, who perceives himself as being stationary relative Paula, observe?  Assuming the light is a single, very brief flash he does not observe the source as moving, but he does see Tony moving towards the source.  He sees light travelling at “c” and Tony travelling at half that speed. Therefore, he sees the light as reaching Tony in 1 tick, but Tony’s clock took 2 ticks, so in the F of R of the outside observer, Tony’s clock is running faster, but he perceives Tony as moving relative to him.

There must be something wrong here, but I can’t see it.
There never was nothing.

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Offline Bill S

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What controls time dilation?
« Reply #5 on: 19/10/2010 18:56:20 »
Quote
There must be something wrong here, but I can’t see it.

Someone must be able to see it!
There never was nothing.

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Offline maffsolo

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What controls time dilation?
« Reply #6 on: 20/10/2010 04:51:19 »
I found this in under Time dilation in wikipedia if it might shead some light on the subject  [?]

"Time dilation: special vs. general theories of relativity
In Albert Einstein's theories of relativity, time dilation in these two circumstances can be summarized:

In special relativity (or, hypothetically far from all gravitational mass), clocks that are moving with respect to an inertial system of observation are measured to be running slower. This effect is described precisely by the Lorentz transformation.
 
In general relativity, clocks at lower potentials in a gravitational field—such as in closer proximity to a planet—are found to be running slower. The articles Gravitational time dilation and Gravitational red shift give a more detailed discussion. Special and general relativistic effects can combine, for example in some time-scale applications mentioned below.

Thus, in special relativity, the time dilation effect is reciprocal: as observed from the point of view of either of two clocks which are in motion with respect to each other, it will be the other clock that is time dilated. (This presumes that the relative motion of both parties is uniform; that is, they do not accelerate with respect to one another during the course of the observations.)

In contrast, gravitational time dilation (as treated in general relativity) is not reciprocal: an observer at the top of a tower will observe that clocks at ground level tick slower, and observers on the ground will agree about that, i.e. about the direction and the ratio of the difference. There is not full agreement, all the observers make their own local clocks out to be correct, but the direction and ratio of gravitational time dilation is agreed by all observers, independent of their altitude."

« Last Edit: 20/10/2010 04:54:50 by maffsolo »

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Offline JP

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What controls time dilation?
« Reply #7 on: 20/10/2010 12:11:51 »
What does an outside observer, who perceives himself as being stationary relative Paula, observe?  Assuming the light is a single, very brief flash he does not observe the source as moving, but he does see Tony moving towards the source.  He sees light travelling at “c” and Tony travelling at half that speed. Therefore, he sees the light as reaching Tony in 1 tick, but Tony’s clock took 2 ticks, so in the F of R of the outside observer, Tony’s clock is running faster, but he perceives Tony as moving relative to him.

Sorry--I didn't see this earlier.  I think it goes like this: If he sees Tony's clock take one tick, but Tony's clock actually took 2 clicks according to Tony, then the clock is ticking more slowly for the moving observer than it is for Tony, and therefore, appeared to slow down.

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Offline Bill S

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What controls time dilation?
« Reply #8 on: 20/10/2010 17:46:22 »
Still struggling! Let's split it into bite sized bits.


1.  Paula’s clock takes 2 ticks while Tony’s takes 3: Paula’s is running slower.

2.  Tony’s clock takes 1 tick while Paula’s takes 2:   Tony’s is running slower.

3.  Observer sees 1 tick while Tony sees 2 ticks. Is this equivalent to saying that the observer’s clock takes 1 tick while Tony’s clock takes 2?  If it is, then to keep our reasoning in line with points 1 & 2, we have to say that the observer’s clock is running slower than tony’s, but this is in the observer's F of R, in which we are regarding him as stationary, (relatively, of course).
There never was nothing.

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Offline Ron Hughes

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What controls time dilation?
« Reply #9 on: 21/10/2010 02:45:10 »
abacus, doesn't look like you are going to get an answer just a run around.
From a drop of water a logician could infer the possibility of an Atlantic or a Niagara without having seen or heard of one or the other. Sherlock Holmes.

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Offline maffsolo

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What controls time dilation?
« Reply #10 on: 21/10/2010 04:23:36 »
Tony is traveling in a train, near light speed.
Tony looks out the window everything is passing by near light speed.
Anything he views as an individual motion of the things he pasts, are moving slow, a wheel spinning, a person blinking etc…

Tony’s frame of reference within, to Tony, it is normal.
 It takes a person (4) ticks to blink.
Same goes for Paula’s frame of reference.

At a flash his train pasts Paula, as she begins to blink:
According to Tony’s clock… it takes her (8) ticks to blink.
He reads Paul’s clock from his frame as being (4) ticks. Her clock is referenced to her blink and its image is also paused at that number tick..

Paula observes Tony as he speeds by or view it as if Tony is at rest and Paula is speeding by in the opposite direction.
According to Paula’s Clock… it takes Tony (8) ticks to blink.
She reads Tony’s clock from her frame as being (4) ticks.

If distance were introduced, let’s say Tony’s train traveled a certain distance.
To Tony the round trip time would be shorter when compared to the time Paula observed, when both clocks are held side by side in the same frame of reference.
« Last Edit: 21/10/2010 04:35:13 by maffsolo »

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Offline Geezer

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What controls time dilation?
« Reply #11 on: 21/10/2010 05:10:39 »
Abacus,

Just in case you are not aware of an experiment that appears to confirm the theory, here's some information on it.

http://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
There ain'ta no sanity clause, and there ain'ta no centrifugal force æther.

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Offline jartza

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What controls time dilation?
« Reply #12 on: 21/10/2010 22:32:18 »
How does light decide how quickly or slowly clocks, either mechanical or biological, run?


Nobody knows, I guess.

But why does a "light clock" slow down when pushed? In other words, why does the spreading of
a beam of light get _slower_ when a spotlight pushed?

Well, for the light that is inside the reflector, when the reflector starts to move, the reflector appears to proceed farther.

Now we have explained one case of slowing down.

Next thing to explain might be: Why does a fast moving light bulb without any reflector
produce a beam of light, that spreads very slowly, if the speed is very high?
 


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Offline jartza

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What controls time dilation?
« Reply #13 on: 22/10/2010 08:12:04 »
Here is something interesting:
When a long compressed spring spinning along its long axis starts to vibrate, when the adhesive tape that keeps the spring compressed breaks, the spinning does not slow down.

This kind of contradicts the law of time dilation we have learned at the college, but slowing down of the spinning would contradict the law of conservation of angular momentum that we have learned at the college.

Now some might say the increase of mass of the spring allows the spin to slow down while angular momentum stays the same, but that would be very erroneous thing to say, because objects do not change their mass spontaneously.

So could you readers accept that the spinning does not slow down?

 







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Offline imatfaal

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What controls time dilation?
« Reply #14 on: 22/10/2010 10:10:40 »
Jartza - I have trouble linking the the spinning spring with time dilation.  I presume that spin and expansion are all at non-relativistic speeds and there is something in the combination of motions that triggers a similarity in your thoughts - I cannot see that similarity, perhaps you could explain.
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Offline jartza

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What controls time dilation?
« Reply #15 on: 22/10/2010 10:50:02 »
Jartza - I have trouble linking the the spinning spring with time dilation.  I presume that spin and expansion are all at non-relativistic speeds and there is something in the combination of motions that triggers a similarity in your thoughts - I cannot see that similarity, perhaps you could explain.

Well, a spinning particle in a particle accelerator slows down its spinning,
while accelerated, because of time dilation, doesn't it? This particle
could be an ion, a charged molecule, or a charged dust particle, if elementary
particles do not spin. So here we have a spin that slows down when linear speed
increases.








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Offline Bill S

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What controls time dilation?
« Reply #16 on: 22/10/2010 16:09:49 »
Quote from: Jartza
why does the spreading of a beam of light get _slower_ when a spotlight pushed?


I'm not sure that I have grasped this. The speed of light does not change, so in what sense does the "spreading" slow down; and in which F of R does this happen?
There never was nothing.

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Offline imatfaal

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What controls time dilation?
« Reply #17 on: 22/10/2010 17:05:54 »
Jartza - I think I will have to think about that.  But I find it difficult to make a judgment on a relativity question through a non-relativistic example that only provides insight because of its similarity to a different relativistic event (and one I am not convinced about). 

Particles travelling at relativistic speed need to be very carefully handled - when you say it slows down its rotation, as measured by whom? in which reference frame?  what sort of spin?
There’s no sense in being precise when you don’t even know what you’re talking about.  John Von Neumann

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Offline jartza

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What controls time dilation?
« Reply #18 on: 22/10/2010 19:41:20 »
Quote from: Jartza
why does the spreading of a beam of light get _slower_ when a spotlight pushed?


I'm not sure that I have grasped this. The speed of light does not change, so in what sense does the "spreading" slow down; and in which F of R does this happen?

The spotlight stands on a slippery table. We pick two random photons in the light beam.
The distance between the photons might grow at speed 0.2 c, for example.

Now we push the spot light, direction of the push is the direction of the light beam. When the spotlight is moving the distance between two randomly chosen photons grows slower, on the average, because the beam is a narrower beam now, in the F of R of the table.

« Last Edit: 22/10/2010 19:44:12 by jartza »

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Offline jartza

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What controls time dilation?
« Reply #19 on: 22/10/2010 23:44:48 »
Jartza - I have trouble linking the the spinning spring with time dilation.  I presume that spin and expansion are all at non-relativistic speeds and there is something in the combination of motions that triggers a similarity in your thoughts - I cannot see that similarity, perhaps you could explain.

When a clock moves it is slow. (this is from a physics book),
so therefore:
When a clock is shot from a cannon it slows down. (this my own reasoning)

Also when a gyroscope is shot from a cannon, it slows down. (also my own reasoning)

But when a spinning cannon shoots a cannon ball, the cannon ball's spinning does not change. (this is what I claim)
 

(if you want you can replace "slows down" with "slows down or speeds up depending on frame of reference", or "changes")



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Offline Bill S

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What controls time dilation?
« Reply #20 on: 23/10/2010 14:51:17 »
Thanks Jartza.

Quote from: J
Now we push the spot light, direction of the push is the direction of the light beam. When the spotlight is moving the distance between two randomly chosen photons grows slower, on the average, because the beam is a narrower beam now, in the F of R of the table.

I see this, but the spreading rate stays the same in the F of R of the spotlight, right?
There never was nothing.

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Offline Bill S

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What controls time dilation?
« Reply #21 on: 23/10/2010 15:04:34 »
Jartza, I've been thinking (always dangerous) about your earlier comments.


1. “When a clock moves it is slow.”  In the F of  R of the observer.
2. “When a clock is shot from a cannon it slows down”  In the F of  R of the observer.
3. “Also when a gyroscope is shot from a cannon, it slows down.”  In the F of  R of the observer.
4. “But when a spinning cannon shoots a cannon ball, the cannon ball's spinning does not change.”  Why would it not change in the F of R of the observer?
There never was nothing.

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Offline jartza

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What controls time dilation?
« Reply #22 on: 23/10/2010 19:15:44 »
4. “But when a spinning cannon shoots a cannon ball, the cannon ball's spinning does not change.”  Why would it not change in the F of R of the observer?


Very simple physics:
Cannon - cannon ball system's center of mass stays were it was, and cannon - cannon ball
system spins the same way as it did.

The spinning spring example maybe illustrates this better, the spring stays in the
same F of R, and spins as before.

BUT a gyroscope shot from a cannon slows down. Why is that? What is the difference? Now
there is something to think about.

« Last Edit: 23/10/2010 19:47:18 by jartza »

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Offline Ron Hughes

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« Reply #23 on: 23/10/2010 19:42:31 »
Because of it's velocity with respect to the observer.
From a drop of water a logician could infer the possibility of an Atlantic or a Niagara without having seen or heard of one or the other. Sherlock Holmes.

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Offline Bill S

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What controls time dilation?
« Reply #24 on: 23/10/2010 21:02:05 »
Quote from: Ron H
Because of it's velocity with respect to the observer.

Would the same not apply to the canon ball?  The canon is spinning, but is otherwise stationary relative to the observer. After firing, the ball is spinning, but is travelling, relative to the observer, so its apparent rotation, in the F of R of the observer is slower.
There never was nothing.

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Offline jartza

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What controls time dilation?
« Reply #25 on: 24/10/2010 07:52:12 »
Because of it's velocity with respect to the observer.

The gyroscope shot from a cannon spins slowly, because of its velocity with respect to the observer? OK I accept that.

Also a cannon ball shot from a spinning cannon spins slowly, because of its velocity with respect to the observer.

BUT the cannon ball shot from a spinning cannon spins at the SAME rate that it did spin when sitting in the barrel, in F of R of the observer.

Now this SAME rate is a slowed down rate, so when a observer starts chasing the cannon ball, the cannon ball's spinning speeds up in the
F of R of the accelerating observer.

I have been misleadingly saying the cannon ball's spinning is "not slowed down", I should have said that "it is the same as before" instead.

So the spinning of a flying gyroscope is slower than the spinning of a gyroscope sitting in the barrel, in the F of R of a still standing observer.

And the flying cannon ball's spinning rate is same as the spinning rate of the cannon ball sitting in the barrel, in the F of R of a still standing observer.


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Offline jartza

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What controls time dilation?
« Reply #26 on: 24/10/2010 16:37:26 »
A little bit of maths about spinning cannons


rest spin of flying cannonball = rest spin of cannonball in the barrel + rest spin of gunpowder that disappears, or changes into energy


Rest spin meaning the angular momentum of an object in the F of R of the object.


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Offline Bill S

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« Reply #27 on: 24/10/2010 17:12:18 »
Quote from: Jartza
BUT the cannon ball shot from a spinning cannon spins at the SAME rate that it did spin when sitting in the barrel, in F of R of the observer.

When the canon ball was in the barrel, it, the canon and the observer were in the same inertial frame. Once fired, it is no longer in that inertial frame, so although its rotational rate, in its own F of R remains the same, it appears slower when viewed from the F of R of either the observer or the canon.  Right?
There never was nothing.

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Offline jartza

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What controls time dilation?
« Reply #28 on: 24/10/2010 18:19:09 »
When the canon ball was in the barrel, it, the canon and the observer were in the same inertial frame. Once fired, it is no longer in that inertial frame, so although its rotational rate, in its own F of R remains the same, it appears slower when viewed from the F of R of either the observer or the canon.  Right?


Nope. If you go to the flying cannonball's frame to observe how fast it spins,
you will observe that firing increased the spinning rate.

And I mean AFTER the firing you go to the flying cannonball's frame.








 


« Last Edit: 24/10/2010 18:23:59 by jartza »

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Offline jartza

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What controls time dilation?
« Reply #29 on: 25/10/2010 02:08:01 »
What happens if a spinning cannon shoots a cannonball that is NOT spinning with the cannon?

Answer: cannonball starts to spin.
A torque is felt by the cannonball when it is put to spin.
Let's call this torque "time dilation torque", because this same torque is responsible for the slowing down of gyroscope that is shot from a cannon.

Now what if we accelerate ourselves into the flying gyroscope's F of R ?
Well, we observe that spinning of the gyroscope accelerates when we accelerate.
So we ask ourselves: what time dilation torque causes this acceleration of spinning?
To answer that we need general relativity. When we are accelerating we experience
there being a gravity field, and all the time that we are accelerating the gyroscope is losing its energy in this gravity field. Now it happens to be so that spinning objects always accelerate their spinning when losing energy in a gravity field, without feeling any torque.

So do we have time dilation of spin now figured out? Is there something to be explained left?

 







« Last Edit: 25/10/2010 02:24:38 by jartza »

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Offline Bill S

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What controls time dilation?
« Reply #30 on: 25/10/2010 13:21:16 »
Quote from: Jartza
Now what if we accelerate ourselves into the flying gyroscope's F of R ?
Well, we observe that spinning of the gyroscope accelerates when we accelerate.

I'm not clear what you are saying here.  Are you saying (1)that the spinning of the gyroscope accelerates relative to us as we accelerate in the course of moving ourselves into the F of R of the gyroscope; or (2)that it would accelerate if the whole system accelerated, after we had arrived in the gyroscope's F of R?

If (1), I see no problem.
If (2), why?
There never was nothing.

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Offline jartza

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What controls time dilation?
« Reply #31 on: 25/10/2010 15:15:01 »
Quote from: Jartza
Now what if we accelerate ourselves into the flying gyroscope's F of R ?
Well, we observe that spinning of the gyroscope accelerates when we accelerate.


I'm not clear what you are saying here.  Are you saying (1)that the spinning of the gyroscope accelerates relative to us as we accelerate in the course of moving ourselves into the F of R of the gyroscope; or (2)that it would accelerate if the whole system accelerated, after we had arrived in the gyroscope's F of R?

If (1), I see no problem.
If (2), why?



I am saying number 1.





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Offline jartza

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« Reply #32 on: 25/10/2010 15:52:00 »
Are you guys following me in this spinning cannon story? Well here is a better story:
 

When we observe an accelerating spinning rocket whose exhaust is spinning like the rocket itself, we do not observe the spinning of the rocket slowing down or speeding up.

When we observe an accelerating spinning rocket whose exhaust is not spinning, because there are some kind of rudders at the nozzle, we observe that the spinning of the rocket speeds up.

When we observe an accelerating spinning rocket whose exhaust is spinning faster than the rocket itself, because there are some kind of rudders at the nozzle, that are adjusted to make the exhaust spin as mentioned, we observe that the spinning of the rocket slows down.

When we observe the first two rockets we see that they have a "speed limit", which is not c. Particularly rocket number two has a low speed limit, like 0.5 c. Rocket number three can achieve speeds arbitrarily close to c, relative to us.










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Offline Bill S

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What controls time dilation?
« Reply #33 on: 10/11/2010 21:25:04 »
Jartza, I've just returned to this thread and read your last post, several times.  there are a couple of things I don't understand.
1. Why should the spinning/not spinning of the exhaust make a difference to our perception of the spinning of the rocket?
2. Why should these factors impose any speed limit (other than c) on the rocket? 
There never was nothing.

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Offline jartza

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« Reply #34 on: 11/11/2010 02:30:39 »
Jartza, I've just returned to this thread and read your last post, several times.  there are a couple of things I don't understand.
1. Why should the spinning/not spinning of the exhaust make a difference to our perception of the spinning of the rocket?

That's how rockets work: exhaust is accelerated this way, the rocket is accelerated the opposite way, this also applies to spinning motion.
(I thought saying "when x observes y then x observes z" was a good way to tell what the F of R is)
Quote
2. Why should these factors impose any speed limit (other than c) on the rocket? 

When a rocket is accelerated to near c, it is not possible to something inside the rocket to continue moving at speed near c.
When something inside a rocket has a speed near c, and it's not possible for that thing to slow down, then it's not possible to accelerate the rocket to near c.
And it's not possible to the spinning of a rocket to slow down without adjustable nozzles, or "rudders", or "spin adjustment rockets".





By the way, this whole thing is based on law of conservation of mass. They don't teach the law of conservation of mass at school. So maybe I should start a thread about conservation of mass.
« Last Edit: 11/11/2010 02:56:31 by jartza »

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Offline Bill S

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What controls time dilation?
« Reply #35 on: 11/11/2010 12:23:30 »
Quote from: jartza
They don't teach the law of conservation of mass at school. So maybe I should start a thread about conservation of mass.

Yes,please.  Then I might not have to step up the Ginkgo biloba, just to get the hang of this spinning stuff. [:I]
There never was nothing.

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Offline jartza

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What controls time dilation?
« Reply #36 on: 19/11/2010 01:45:07 »
Oh yes time dilation mechanism needs an explanation.


Let's attach some radioactive material on the center part of a big flywheel.
The radioactive stuff starts heating the flywheel. No heat is lost to anywhere else.
The flywheel is frictionless. Then we make the flywheel spin. What can we say about
the spinning rate?


Flywheel slows down, as heat mass-energy travels from center to periphery, it's the
Coriolis force thing.


Let's attach a spring on the center of a flywheel disk. Then we attach another disk
into the other end of the spring. Then we press the disks together. The spring becomes
compressed. Then we tie this thing with a string. This thing we have constructed is a
flywheel. It's frictionless flywheel. Now we make the flywheel spin. At some moment
the sting breaks. What can we say about the spinning rate, when the string breaks?


Flywheel slows down, it's the Coriolis force again. The mass-energy that was stored
in the spring travels from center to periphery of the flywheel.

Relativity says that when a flywheel is made to spin very fast the thermal motion
of molecules is slowed down, they call it time dilation. When thermal motion of the
molecules of a spinning flywheel increases the flywheel is slowed down, what do we
call this, reverse time dilation?

If I would claim that heat causes time dilation, then people in science forums would
say I'm nuts. So I claim that heat does NOT cause time dilation. So in the case
of a flywheel made of two parts, when these two parts are made to vibrate, then there
is no time dilation related to the motion. (The vibration energy is equivalent to heat
energy you see)

So the explanation of time dilation is that there is no time dilation, but there
are some cases when something slows down when something else speeds up.





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Offline JP

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What controls time dilation?
« Reply #37 on: 19/11/2010 11:42:25 »
So the explanation of time dilation is that there is no time dilation, but there
are some cases when something slows down when something else speeds up.

 [???]

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Offline jartza

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« Reply #38 on: 20/11/2010 07:39:18 »
JP here's a question to you:

How do we accelerate a spinning object, so that we don't disturb the spinning?

(There are different ways, that have different effects on spinning rate)


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Offline jartza

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« Reply #39 on: 22/11/2010 07:25:56 »

One way to accelerate a flywheel is to put it in a rocket. In the rocket a clock slows down because of time dilation, and the flywheel slows down because of Coriolis force. If we eliminate the Coriolis force, a person with his brain slowing down observing a flywheel that is not slowing down, will say that "this flywheel is speeding up".





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Offline peppercorn

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What controls time dilation?
« Reply #40 on: 22/11/2010 10:55:24 »

One way to accelerate a flywheel is to put it in a rocket. In the rocket a clock slows down because of time dilation, and the flywheel slows down because of Coriolis force. If we eliminate the Coriolis force, a person with his brain slowing down observing a flywheel that is not slowing down, will say that "this flywheel is speeding up".

No he won't. if "his brain is slowing down" - you mean he is in the rocket too, yes? But the flywheels being exposed to the same time dilation as the astronaut so his observation of it would be as normal.

If the flywheel were back on Earth and slowing (although I'm not certain how this would be down to the Coriolis effect), he might observe no change in its speed if the acceleration of his ship was just acceleration of his right.

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Offline jartza

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« Reply #41 on: 22/11/2010 12:51:06 »
No he won't. if "his brain is slowing down" - you mean he is in the rocket too, yes? But the flywheels being exposed to the same time dilation as the astronaut so his observation of it would be as normal.

If the flywheel were back on Earth and slowing (although I'm not certain how this would be down to the Coriolis effect), he might observe no change in its speed if the acceleration of his ship was just acceleration of his right.

Here's a method to accelerate a spinning disk:
You place the disk horizontally. Under the disk there should be an "under disk"
The under disk must always spin like the upper disk, sensors and motors take care of that. Then there is a mechanism that gives every part of the upper disk regular kicks, this "kick unit" is attached to the under disk. Now we have managed to produce such kicks that don't affect the spinning of the upper disk.

...And this way time dilation effect is eliminated from the spinning of the disk.


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Offline peppercorn

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What controls time dilation?
« Reply #42 on: 22/11/2010 14:46:36 »
Here's a method to accelerate a spinning disk:
You place the disk horizontally. Under the disk there should be an "under disk"
The under disk must always spin like the upper disk, sensors and motors take care of that. Then there is a mechanism that gives every part of the upper disk regular kicks, this "kick unit" is attached to the under disk. Now we have managed to produce such kicks that don't affect the spinning of the upper disk.

...And this way time dilation effect is eliminated from the spinning of the disk.

This may be too far beyond my intellect, but I've really no idea what this device is or what relevance it has to time or its modulation.

I may regret suggesting this, but how about a diagram?

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Offline jartza

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« Reply #43 on: 22/11/2010 16:04:12 »
This may be too far beyond my intellect, but I've really no idea what this device is or what relevance it has to time or its modulation.

I may regret suggesting this, but how about a diagram?


Here is very simple device:
A spinning hotplate. (we call it SH) (the hotplate is hot)
This device exerts radiation pressure and radiation torque on objects.
Let's say SH is exerting radiation torque on an object that is free to spin. The object starts to spin to the same direction as the SH, this spinning is slowly accelerating. When the SH and the object spin at the same rate the torque that SH exerts on the object is zero. Now SH is exerting on the object radiation pressure, but no radiation torque.

SH can be used to accelerate spinning objects without disturbing the spinning, by adjusting the SH so that torque is zero .

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Offline Bill S

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What controls time dilation?
« Reply #44 on: 22/11/2010 16:08:20 »
Quote from: jartza
And this way time dilation effect is eliminated from the spinning of the disk

In which F of R is the time dilation effect eliminated?
There never was nothing.

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Offline peppercorn

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What controls time dilation?
« Reply #45 on: 22/11/2010 16:22:06 »
Let's say SH is exerting radiation torque on an object that is free to spin.

One of these?
http://en.wikipedia.org/wiki/Crookes_radiometer

All these 'devices' are lovely, but they seem to have little to do with time or effects on it.
Please stick to the thread (if you must at all).

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Offline jartza

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« Reply #46 on: 22/11/2010 21:27:07 »

In which F of R is the time dilation effect eliminated?

Any F of R. Not accelerating F of R though.

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Offline jartza

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« Reply #47 on: 22/11/2010 21:49:22 »

One of these?
http://en.wikipedia.org/wiki/Crookes_radiometer

All these 'devices' are lovely, but they seem to have little to do with time or effects on it.
Please stick to the thread (if you must at all).

Quit fretting [:)]
'Device' 2 is the same device as 'device' 1.
By device 2 if was clarifying device 1 for you.
So here's device 2:
Spinning hotplate emits photons, that carry angular momentum to a black object, that experiences torque.

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Offline peppercorn

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What controls time dilation?
« Reply #48 on: 22/11/2010 22:29:41 »
One of these?
Quit fretting [:)]
'Device' 2 is the same device as 'device' 1.
By device 2 if was clarifying device 1 for you.
So here's device 2:
Spinning hotplate emits photons, that carry angular momentum to a black object, that experiences torque.

Again, perhaps diagrams have a chance to 'illuminate' me and any others not so able to make the, erm, intuitive jumps.

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Offline jartza

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« Reply #49 on: 23/11/2010 16:12:33 »
Again, perhaps diagrams have a chance to 'illuminate' me and any others not so able to make the, erm, intuitive jumps.

You are just complaining all the time [:)] "don't post this stuff", "post diagrams"
This is how really fast moving black body radiates:

[diagram=610_0]

So how does a really fast spinning black disk radiate?