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Offline MikeS

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Is relativistic velocity a noticeable effect?
« on: 26/09/2011 16:13:12 »
If the Universe is expanding at a significant fraction of the speed of light then we are moving at a significant fraction of the speed of light.
Relativistic speed dilates time.  If the speed of the expansion is increasing then time is constantly dilating.  How should we interpret this in terms of what we observe?


 

Offline imatfaal

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Is relativistic velocity a noticeable effect?
« Reply #1 on: 26/09/2011 16:39:02 »
You need to get your frames of reference and relative velocities down pat.  Time dilation works on two frames - within your own frame time is never dilated, looked at from another frame then it often is.  What frame exterior to the universe are you looking from?  Relative speeds between galaxies and clusters within the universe is accounted for in cosmological working where precision is required.
 

Offline MikeS

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Is relativistic velocity a noticeable effect?
« Reply #2 on: 26/09/2011 17:25:33 »
If we look at a galaxy far far away and observe it to be receding at a relativistic speed then time has slowed down for it but to an individual in that galaxy they will see time progressing as normal.
If that individual observes our galaxy then they will observe time here as being slowed, while we think time is passing as normal.  So, if time has dilated at a distance and here then it must have dilated throughout the observable universe.
 

Offline Soul Surfer

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Is relativistic velocity a noticeable effect?
« Reply #3 on: 26/09/2011 23:50:21 »
You are tending to think of time as some sort of absolute thing like a clock ticking throughout the universe.  This is wrong.  Time is a local phenomenon and not absolute.
 

Offline MikeS

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Is relativistic velocity a noticeable effect?
« Reply #4 on: 27/09/2011 07:18:07 »
You are tending to think of time as some sort of absolute thing like a clock ticking throughout the universe.  This is wrong.  Time is a local phenomenon and not absolute.

Yes, that is how I think of time.  Time is an effect of 'something' in the universe, so it seems natural that the universe has an average 'passage' of time which can vary at any locality.

Even if this is incorrect the universe can be thought of as made up of an infinite number of space-time coordinates.  Any two of which, if they are of great distance and relative to each other are moving apart at relativistic speed.  Therefore, time must be dilating everywhere.  Whether time is absolute or not the result is the same.  Taking an average of all the 'local' times gives an 'average' time.


If my thinking on this is wrong then I would like to understand why.
« Last Edit: 27/09/2011 07:20:41 by MikeS »
 

Offline Soul Surfer

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Is relativistic velocity a noticeable effect?
« Reply #5 on: 27/09/2011 09:32:21 »
Time is just a convenient way of expressing the progression of events locally and how the rest of the universe appears from this local point of view it is nothing more than this it is most definitely not the big clock that keeps the computer going.
 

Offline MikeS

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Is relativistic velocity a noticeable effect?
« Reply #6 on: 27/09/2011 09:39:37 »
Time is just a convenient way of expressing the progression of events locally and how the rest of the universe appears from this local point of view it is nothing more than this it is most definitely not the big clock that keeps the computer going.

Is this a personal viewpoint or is there evidence (references) that this is true?
 

Offline MikeS

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Is relativistic velocity a noticeable effect?
« Reply #7 on: 27/09/2011 09:45:05 »
If we look at a galaxy far far away and observe it to be receding at a relativistic speed then time has slowed down for it but to an individual in that galaxy they will see time progressing as normal.
If that individual observes our galaxy then they will observe time here as being slowed, while we think time is passing as normal.
  So, if time has dilated at a distance and here then it must have dilated throughout the observable universe.

Surely, this is a prediction of Relativity?

We can not know that our clocks have slowed other than by an observation over a great distance.
« Last Edit: 27/09/2011 09:55:00 by MikeS »
 

Offline imatfaal

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Is relativistic velocity a noticeable effect?
« Reply #8 on: 27/09/2011 10:25:48 »
Time is dilated relative to somewhere else and is reciprocal - you cannot look at individual circumstances and sum to the whole.  If you take the universe as a frame then you need to step out - and you cannot.  If you take the milky way as your frame then other galaxies will be time dilated.  this has been shown by the evolution of primordial galactic clusters and their constituents in the distant sky being slower than those closer.
 

Offline simplified

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Is relativistic velocity a noticeable effect?
« Reply #9 on: 27/09/2011 13:00:25 »
Time is dilated relative to somewhere else and is reciprocal - you cannot look at individual circumstances and sum to the whole.  If you take the universe as a frame then you need to step out - and you cannot.  If you take the milky way as your frame then other galaxies will be time dilated.  this has been shown by the evolution of primordial galactic clusters and their constituents in the distant sky being slower than those closer.
That is not surprising if distance between galaxies increases.Because photons of first event arrive faster than photons of second event to us. :D
 

Offline imatfaal

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Is relativistic velocity a noticeable effect?
« Reply #10 on: 27/09/2011 13:24:01 »
Time is dilated relative to somewhere else and is reciprocal - you cannot look at individual circumstances and sum to the whole.  If you take the universe as a frame then you need to step out - and you cannot.  If you take the milky way as your frame then other galaxies will be time dilated.  this has been shown by the evolution of primordial galactic clusters and their constituents in the distant sky being slower than those closer.
That is not surprising if distance between galaxies increases.Because photons of first event arrive faster than photons of second event to us. :D

Note; I said slower, rather than at an later time.  After all other known effects are taken into account the slower pace is still there
 

Offline jartza

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Is relativistic velocity a noticeable effect?
« Reply #11 on: 27/09/2011 18:05:27 »
I would say that if we look at a clock that "moves" away from us at speed 0.5 c, because of expansion of space, and a clock that moves away from us at speed 0.5 c, then we see the clock that "moves" is running faster than the clock that moves.

Because: "moving" can reach speeds like 5 c, while moving is always slower than 1 c.

If we look at a galaxy that is "moving" at speed 0.9 c, and moving at zero speed, then we see no Lorentz contraction in the galaxy. Or do we see?

 

Offline simplified

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Is relativistic velocity a noticeable effect?
« Reply #12 on: 27/09/2011 18:13:34 »
Time is dilated relative to somewhere else and is reciprocal - you cannot look at individual circumstances and sum to the whole.  If you take the universe as a frame then you need to step out - and you cannot.  If you take the milky way as your frame then other galaxies will be time dilated.  this has been shown by the evolution of primordial galactic clusters and their constituents in the distant sky being slower than those closer.
That is not surprising if distance between galaxies increases.Because photons of first event arrive faster than photons of second event to us. :D

Note; I said slower, rather than at an later time.  After all other known effects are taken into account the slower pace is still there
Was I saying that 'later time'?
Photons of start of the event arrive by short way to us,photons of finish of the event arrive by long way.It increases time of our observing of flow of the event.
Even if it is taken into account,that is not the obligatory proof of twin paradox  . Only following experiment can be such proof:  a first clock and a second clock have synchronized on a satellite. Then the second clock travels to the earth (dominant mass),it exists long time on the earth, then travels back to insignificant mass(people check the result on the satellite ). The result of such experiment is  main thing to  proof of the paradox. :P
« Last Edit: 27/09/2011 18:50:49 by simplified »
 

Offline MikeS

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Is relativistic velocity a noticeable effect?
« Reply #13 on: 28/09/2011 17:44:54 »
Time is dilated relative to somewhere else and is reciprocal - you cannot look at individual circumstances and sum to the whole.  If you take the universe as a frame then you need to step out - and you cannot.  If you take the milky way as your frame then other galaxies will be time dilated.  this has been shown by the evolution of primordial galactic clusters and their constituents in the distant sky being slower than those closer.
[/quote}

"you cannot look at individual circumstances and sum to the whole." 
Why not?  Everywhere in the universe must be subject to the passage of time.  Can you quote any references please?
 

Offline imatfaal

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Is relativistic velocity a noticeable effect?
« Reply #14 on: 28/09/2011 17:59:40 »
Mike It's not called relativity just cos that's a nice name.  Measurements and calculations depend on the frame of reference.  there is no "fullgod frame" from which everything can be judged (h/t tar2 at SFN) and in which time is absolute and measurements are "correct".  A local frame on earth has no time dilation - the same point viewed from our observatory on pluto sees earthbound clocks running slow, from the edge of the oort cloud they seem slower still; which is correct?  They all are - so which are you going to put into your sum? 

Relativity Special General and Cosmological - Wolfgang Rindler
 

Offline imatfaal

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Is relativistic velocity a noticeable effect?
« Reply #15 on: 28/09/2011 18:09:11 »
Time is dilated relative to somewhere else and is reciprocal - you cannot look at individual circumstances and sum to the whole.  If you take the universe as a frame then you need to step out - and you cannot.  If you take the milky way as your frame then other galaxies will be time dilated.  this has been shown by the evolution of primordial galactic clusters and their constituents in the distant sky being slower than those closer.
That is not surprising if distance between galaxies increases.Because photons of first event arrive faster than photons of second event to us. :D

Note; I said slower, rather than at an later time.  After all other known effects are taken into account the slower pace is still there
Was I saying that 'later time'?
Photons of start of the event arrive by short way to us,photons of finish of the event arrive by long way.It increases time of our observing of flow of the event.
Even if it is taken into account,that is not the obligatory proof of twin paradox  . Only following experiment can be such proof:  a first clock and a second clock have synchronized on a satellite. Then the second clock travels to the earth (dominant mass),it exists long time on the earth, then travels back to insignificant mass(people check the result on the satellite ). The result of such experiment is  main thing to  proof of the paradox. :P

No you said photons "arrive faster" - as all photons travel at c, and faster means travelling at greater velocity I decided you meant something possible. 

After all things are taken into account (the greater distance to travel for photons emitted by the end of the event etc) then these stellar evolutions seem to take longer when the galaxy is moving with high relative velocity - this timing difference is correctly explained by time dilation due to rel vel. 

on the twin paradox - there is no paradox, only a misunderstanding of sr leading to people not being able to reconcile the strange results of relativistic velocities; no experiment is needed to prove or disprove the twin paradox as there is no paradox

here is a link to the physics faq twin paradox which shows in multiple ways why it isn't a problem
 

Offline MikeS

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Is relativistic velocity a noticeable effect?
« Reply #16 on: 29/09/2011 07:37:12 »
Mike It's not called relativity just cos that's a nice name.  Measurements and calculations depend on the frame of reference.  there is no "fullgod frame" from which everything can be judged (h/t tar2 at SFN) and in which time is absolute and measurements are "correct".  A local frame on earth has no time dilation - the same point viewed from our observatory on pluto sees earthbound clocks running slow, from the edge of the oort cloud they seem slower still; which is correct?  They all are - so which are you going to put into your sum? 

Relativity Special General and Cosmological - Wolfgang Rindler

My point being that from any distant reference frame time on Earth is dilated (as you mention).  The only place you can not see this directly is in the time frame of the Earth.  We can not see it because we are in that dilating time frame.  When we look outside the Earth's time frame and see all other distant time frames as dilated then that is evidence that our own time frame is dilated.

What is wrong with this argument?
« Last Edit: 29/09/2011 07:42:53 by MikeS »
 

Offline yor_on

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Is relativistic velocity a noticeable effect?
« Reply #17 on: 29/09/2011 14:47:08 »
Mike, my turn on it is this. There is a universal 'time'. That 'universal' time is proven each time you ala startrek 'teleport' to that other frame of reference which clock was so slow before, according to you. Presto, as soon as you're there its 'time' will be yours, no difference measurable. And if you had a defined 'life span' counted in heartbeats, then you will find it to be the same, no matter where you go, or how 'fast' you go.

So yes, there is a 'universal clock'. But, as Soulsurfer pointed out, it's always a 'local one' and also the one that defines all other 'clocks' you can find measuring other frames. It's not related to the 'whole of the universe' as a ocean might be seen as related to the fish, it's more of a 'same' very local 'beat'. If it wasn't that way you wouldn't have a time dilation as the clock then shouldn't differ at all, no matter at what 'frame' you measure it, relative yours. But it is indeed 'universal' in that that you never will find it to give you a different beat relative, for example, your heartbeats.

SpaceTime is like a mosaic, we see the pieces represented as different 'beats' or 'clocks' relative the piece we are at, but as soon as we go there the piece will fit our clock. And there is nowhere you will live any longer. You can't change your metabolic rate by falling towards the event horizon for example. Not as measured locally, and you won't get any more heartbeats to dispose of :)
==

And it's directly related to the way radiation 'ticks', invariantly. As long as 'c' will be found to be a 'constant' locally, this will be true. And the really weird thing to consider here, that too many ignores, is that 'c' doesn't care where you are, or how fast you go. Locally the speed of light in a vacuum always will give you the same value, be it measured from a speeding rocket, or at a neutron star.

« Last Edit: 29/09/2011 14:59:21 by yor_on »
 

Offline imatfaal

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Is relativistic velocity a noticeable effect?
« Reply #18 on: 29/09/2011 17:45:15 »
Mike It's not called relativity just cos that's a nice name.  Measurements and calculations depend on the frame of reference.  there is no "fullgod frame" from which everything can be judged (h/t tar2 at SFN) and in which time is absolute and measurements are "correct".  A local frame on earth has no time dilation - the same point viewed from our observatory on pluto sees earthbound clocks running slow, from the edge of the oort cloud they seem slower still; which is correct?  They all are - so which are you going to put into your sum? 

Relativity Special General and Cosmological - Wolfgang Rindler

My point being that from any distant reference frame time on Earth is dilated (as you mention).  The only place you can not see this directly is in the time frame of the Earth.  We can not see it because we are in that dilating time frame.  When we look outside the Earth's time frame and see all other distant time frames as dilated then that is evidence that our own time frame is dilated.

What is wrong with this argument?

Everything is dilated - so nothing is dilated.  There is no universal time; if everything is wrong by 1.5times then everything is correct (and you can ignore the factor).  to get the dilation to be apparent you need a set basis, and that set basis is everywhere (it is here, it is on pluto, it is on α-centuri and on the intergalactic equivalent of scotch corner - barnard's star). if we transfer our laboratory from earth to a space port orbiting barnard's star we would still see the same thing - so the easiest and most logical thing to do is to call that zero/baseline/normal.  to measure a galactic effect you need to be well o/s the galaxy - to measure a local galatic cluster effect... to measure a universal effect you need to be outside the universe, and at present that is an impossibility even to comprehend
 

Offline simplified

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Is relativistic velocity a noticeable effect?
« Reply #19 on: 30/09/2011 18:18:46 »
Time is dilated relative to somewhere else and is reciprocal - you cannot look at individual circumstances and sum to the whole.  If you take the universe as a frame then you need to step out - and you cannot.  If you take the milky way as your frame then other galaxies will be time dilated.  this has been shown by the evolution of primordial galactic clusters and their constituents in the distant sky being slower than those closer.
That is not surprising if distance between galaxies increases.Because photons of first event arrive faster than photons of second event to us. :D

Note; I said slower, rather than at an later time.  After all other known effects are taken into account the slower pace is still there
Was I saying that 'later time'?
Photons of start of the event arrive by short way to us,photons of finish of the event arrive by long way.It increases time of our observing of flow of the event.
Even if it is taken into account,that is not the obligatory proof of twin paradox  . Only following experiment can be such proof:  a first clock and a second clock have synchronized on a satellite. Then the second clock travels to the earth (dominant mass),it exists long time on the earth, then travels back to insignificant mass(people check the result on the satellite ). The result of such experiment is  main thing to  proof of the paradox. :P

No you said photons "arrive faster" - as all photons travel at c, and faster means travelling at greater velocity I decided you meant something possible. 

After all things are taken into account (the greater distance to travel for photons emitted by the end of the event etc) then these stellar evolutions seem to take longer when the galaxy is moving with high relative velocity - this timing difference is correctly explained by time dilation due to rel vel. 

on the twin paradox - there is no paradox, only a misunderstanding of sr leading to people not being able to reconcile the strange results of relativistic velocities; no experiment is needed to prove or disprove the twin paradox as there is no paradox

here is a link to the physics faq twin paradox which shows in multiple ways why it isn't a problem
'Good theory does not need new experiments' sounds like 'good dictator does not need honest elections'. :D
 

Offline MikeS

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Is relativistic velocity a noticeable effect?
« Reply #20 on: 03/10/2011 08:32:49 »
Mike It's not called relativity just cos that's a nice name.  Measurements and calculations depend on the frame of reference.  there is no "fullgod frame" from which everything can be judged (h/t tar2 at SFN) and in which time is absolute and measurements are "correct".  A local frame on earth has no time dilation - the same point viewed from our observatory on pluto sees earthbound clocks running slow, from the edge of the oort cloud they seem slower still; which is correct?  They all are - so which are you going to put into your sum? 

Relativity Special General and Cosmological - Wolfgang Rindler

My point being that from any distant reference frame time on Earth is dilated (as you mention).  The only place you can not see this directly is in the time frame of the Earth.  We can not see it because we are in that dilating time frame.  When we look outside the Earth's time frame and see all other distant time frames as dilated then that is evidence that our own time frame is dilated.

What is wrong with this argument?

Everything is dilated - so nothing is dilated.  There is no universal time; if everything is wrong by 1.5times then everything is correct (and you can ignore the factor). to get the dilation to be apparent you need a set basis, and that set basis is everywhere (it is here, it is on pluto, it is on α-centuri and on the intergalactic equivalent of scotch corner - barnard's star). if we transfer our laboratory from earth to a space port orbiting barnard's star we would still see the same thing - so the easiest and most logical thing to do is to call that zero/baseline/normal.  to measure a galactic effect you need to be well o/s the galaxy - to measure a local galatic cluster effect... to measure a universal effect you need to be outside the universe, and at present that is an impossibility even to comprehend

For an object traveling at relativistic speed their clocks run slower according to a distant observer.  This effect is reciprocal.  If the effect is reciprocal then how can we observe it?
Surely, we canít.  In which case how do we know the effect is real?  We can compare the passage of time at the present with the passage of time in the past to see if there is any difference.  How would this difference manifest itself?  It would show as a red or blue shift in the photons reaching us now that were emitted in the past.

A red shift would indicate that time is contracted now and was dilated in the past.
Explanation.  Light has a certain frequency  and wavelength.  Light emitted in the past had that same specific frequency and wavelength.  As time contracts, a second becomes, by comparison, shorter.  Fewer cycles arrive in a shorter second and their wavelength is longer.  This is a red-shift.  This red-shift is due to time contraction now in comparison to the past.  If the time contraction is continuous then the red-shift will increase.

A blue shift would indicate that time is dilated now and was contracted in the past.
Explanation.  Light has a certain frequency  and wavelength.  Light emitted in the past had that same specific frequency and wavelength.  As time contracts, a second becomes, by comparison, longer.  A greater number of cycles arrive in a longer second and their wavelength is shorter.  This is blue shift.  This blue-shift is due to time dilation now in comparison to the past.  If time dilation is continuous then the blue-shift will increase.



"Everything is dilated - so nothing is dilated."
You could argue that point if it didn't leave any evidence of change.  If time is continually dilating then it must have been more contracted in the past.  This would show as light from the past being red-shifted, which it is.

"There is no universal time;"
I really do not understand that argument.  Time, the same as gravity must exist everywhere in the universe.  Its dilation/contraction varies at different localities just the same as the strength of gravity varies.  If everywhere has a passage of time then the universe must have an average passage of time.

"to measure a universal effect you need to be outside the universe",
Yes, I believe if you were outside the universe you would see all clocks speeding up and you could measure this. 
If we knew that the time dilation/contraction red-shift was the only component of the cosmological red-shift then we could measure this and calculate time dilation/contraction.
Unfortunately, time dilation/contraction red-shift is 'mixed' up with the expansion red-shift (Hubble)and we have no way of knowing what proportion of the total red-shift either contributes.
 

Offline damocles

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Is relativistic velocity a noticeable effect?
« Reply #21 on: 03/10/2011 10:06:17 »
Might I suggest that we are looking at this issue on the wrong scale of distance and time. I am not a particle physicist, but it seems to me that the ball for direct proof of special relativistic time dilation is in their court, in the first instance.

Possible experimental approach: Do a fairly typical particle type experiment to produce some very short-lived particles, moving fast, no doubt, but nowhere near the speed of light.

Now repeat the experiment in a setup where the same particles are moving close to the speed of light in the laboratory frame.

The average lifetime of the first population of particles, as measured in the LAB frame should be significantly shorter than the average lifetime of the second lot, as measured in the LAB frame.
 

Offline CPT ArkAngel

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« Reply #22 on: 03/10/2011 12:04:53 »
Yes Damocles, it has been proved. What i don't know it is if the reverse frame experience has been done.

A simple experience would be to synchronize two atomic clocks on earth. An astronaut takes one of the clock on the International Space Station. A year later, an astronaut takes the other clock to the space station and compares their time. After separating the effects of general relativity and special relativity, what is the effect of special relativity?
 

Offline JP

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« Reply #23 on: 03/10/2011 15:45:00 »
Might I suggest that we are looking at this issue on the wrong scale of distance and time. I am not a particle physicist, but it seems to me that the ball for direct proof of special relativistic time dilation is in their court, in the first instance.

Possible experimental approach: Do a fairly typical particle type experiment to produce some very short-lived particles, moving fast, no doubt, but nowhere near the speed of light.

Now repeat the experiment in a setup where the same particles are moving close to the speed of light in the laboratory frame.

The average lifetime of the first population of particles, as measured in the LAB frame should be significantly shorter than the average lifetime of the second lot, as measured in the LAB frame.

You're right that this would be an easy test case of SR, and indeed it has been tested!
http://en.wikipedia.org/wiki/Time_dilation_of_moving_particles
 

Offline simplified

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« Reply #24 on: 03/10/2011 16:46:36 »
A traveling tiny mass (relatively of dominant mass) has a slowed time, this is proved.
 A traveling dominant mass (relatively of tiny mass) has a slowed time, this is not proved!
 

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