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Author Topic: What happens when time slows down at light speed?  (Read 11576 times)

Offline David Cooper

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Re: What happens when time slows down at light speed?
« Reply #25 on: 24/02/2014 19:32:39 »
       There has been a wealth of experiments and observations showing that neutrinos travel at the speed of light and that they can change flavor while moving at that speed.  If they where frozen in time they could not undergo the change.

The contortions introduced by SR/GR reduce the distance to zero for any trip made by anything that travels at the speed of light, so that leaves no room for neutrinos to change flavour at regular intervals along the way. Of course, give a neutrino the tiniest bit of mass and the problem may go away for both theories because it presumably won't quite be travelling at the speed of light.
« Last Edit: 24/02/2014 19:34:10 by David Cooper »
 

Offline David Cooper

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Re: What happens when time slows down at light speed?
« Reply #26 on: 25/02/2014 18:56:39 »
Out of interest, if neutrinos really do travel at the speed of light, how far do they normally travel through our frame of reference before changing flavour, and could this be used to pin down a preferred frame?
 

Offline jeffreyH

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Re: What happens when time slows down at light speed?
« Reply #27 on: 25/02/2014 20:28:55 »
Out of interest, if neutrinos really do travel at the speed of light, how far do they normally travel through our frame of reference before changing flavour, and could this be used to pin down a preferred frame?

Surely they would be affected by gravity as light is. Are you thinking of the distance between 2 consecutive changes?
 

Offline jeffreyH

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Re: What happens when time slows down at light speed?
« Reply #28 on: 25/02/2014 20:35:17 »
Any particular frame in the entire universe is running at a different speed to everything else that has a frame not equivalent with it's own by a particular amount. This amount could be 1 nanosecond or 8 years slower or faster.
I have understood nothing of this passage. Can you please make a specific example?

To lightarraow: All with respect to relative time dilation.

If two frames are running parallel to each other at the same velocity
"velocity" measured in which frame?
Quote

To lightarrow If the vector direction and velocity of two frames are the same they can be considered equivalent. They will be separated by distance n but be parallel to each other.

they are equivalent. Any difference in vector direction makes them un-equivalent and therefore they run at different speeds however minute the difference.
What does "they run at different speeds" means? Are you referring to time rhythm or something of this kind? Or?

Time dilation.
« Last Edit: 25/02/2014 20:37:02 by jeffreyH »
 

Offline sciconoclast

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Re: What happens when time slows down at light speed?
« Reply #29 on: 26/02/2014 02:02:24 »
Good to see some interest:
                                               The first neutrinos and the first photons from event sources billions of light years away reach detectors on earth simultaneously.

Neutrinos traveling from an earth bound source to an earth bound detector ( within the same reference frame ) arrive simultaneously with gamma rays, but more importantly the distance or time required for a change in neutrino type is short. 

I had mentioned in a post some time ago the possibility that the reason for the apparent contradictions could be our limited ability to determine minute differences in speed and minute mass.  I am currently leaning towards neutrinos as having mass and traveling at the speed of light.  There is a possibility that the parameters defining the differences between mass and energy are much more muddled than we currently believe.

When I heard the same sentiment from someone working in this field I asked them what this would mean for relativity.  They replied that they were not interested in theory, only measurements.  Perhaps we do need more data.
 

Offline lightarrow

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Re: What happens when time slows down at light speed?
« Reply #30 on: 26/02/2014 11:53:59 »
Any particular frame in the entire universe is running at a different speed to everything else that has a frame not equivalent with it's own by a particular amount. This amount could be 1 nanosecond or 8 years slower or faster.
I have understood nothing of this passage. Can you please make a specific example?

To lightarraow: All with respect to relative time dilation.

If two frames are running parallel to each other at the same velocity
"velocity" measured in which frame?
Quote

To lightarrow If the vector direction and velocity of two frames are the same they can be considered equivalent. They will be separated by distance n but be parallel to each other.

they are equivalent. Any difference in vector direction makes them un-equivalent and therefore they run at different speeds however minute the difference.
What does "they run at different speeds" means? Are you referring to time rhythm or something of this kind? Or?

Time dilation.
Ok. Then your statement:
<<Any particular frame in the entire universe is running at a different speed to everything else that has a frame not equivalent with it's own by a particular amount.>>
has no meaning.

--
lightarrow
 

Offline jeffreyH

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Re: What happens when time slows down at light speed?
« Reply #31 on: 26/02/2014 14:36:09 »
<<Any particular frame in the entire universe is running at a different speed to everything else that has a frame not equivalent with it's own by a particular amount.>>
has no meaning.

--
lightarrow

It could have been worded better.
 

Offline David Cooper

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Re: What happens when time slows down at light speed?
« Reply #32 on: 26/02/2014 18:47:27 »
Out of interest, if neutrinos really do travel at the speed of light, how far do they normally travel through our frame of reference before changing flavour, and could this be used to pin down a preferred frame?

Surely they would be affected by gravity as light is. Are you thinking of the distance between 2 consecutive changes?

If there is a distance they have to travel before they change form, that distance will be either be measured as different for different frames (with one frame maximising them) or else the distance will vary depending on the rest frame of the source of the neutrinos. The latter would need to be the case if there is no preferred frame.
 

Offline sciconoclast

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Re: What happens when time slows down at light speed?
« Reply #33 on: 07/03/2014 01:20:29 »
Justin:
           Your comment that time stops at the speed of light according to relativity is correct despite some of the comments such as you can't make such blanket statements.  Einstein made them.

All of the discussion about different frames of reference are irrelevant as your example can take place completely within one reference frame.

The speed of light is universal and the same in all reference frames.  For this reason it is often called the universal yard stick.

This was already known when Einstein was developing his theories.  He needed a way to account for this in his concept for doing away with preferred reference frames.  He accomplished this by having time intervals contract with velocity the same as other dimensions;  making the time dimension's value zero in any reference frame at the speed of light.

Some of the questions I raised can also be dealt with within a single reference frame.  Neutrino speed and osculation can be measured on earth.

The Michelson-Gale-Pearson experiment was a variation of the Sagnac experiment in which the earth itself was the turntable.  Even though the light paths were traveling against and with the earth's rotation over different portions of the distance they returned simultaneously.  The speed of light had adjusted relative to the rotating reference frame of the rotating gravitational field or earth mass.

By the way, Einstein incorrectly predicted the results in both the Sagnac and MGP experiments.  He was later saved by Minkowski who re-interpreted the experiment.  Einstein was often said to be the worst interpreter of his own theory [ Herman Minkowski was responsible for most of the math in Einstein's GR and SR ].

In the Hafele-Keating experiment atomic clocks are flown in opposite east and west directions at the same speed relative to the earth.  Einstein correctly predicted that the east atomic clock would have been slower.
Supposedly this was because the east clock was moving faster having had the motion of the earth added to it.
For the earth's speed to be added and subtracted then the reference frame could not be rotating with the earth.   

One experiment is a SR experiment and the other is a GR experiment but it seems to me that the reference frame should still be the same in both experiments.

I agree with Justin that time is not a factor.  I think that what could be called the time vector remains the same ( at least within the shock wave of the Big Bang ) and that everything else adjust to maintain their defining parameters relative to the gravitational filed and other  background ambients ( as per the video I mentioned earlier in this thread ).
 

Offline JP

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Re: What happens when time slows down at light speed?
« Reply #34 on: 07/03/2014 01:46:15 »
Justin:
           Your comment that time stops at the speed of light according to relativity is correct despite some of the comments such as you can't make such blanket statements.  Einstein made them.

Since we're a science forum and simply stating your opinion doesn't make it true, here's some arguments that show you cannot, indeed, move at light speed and asking about "If I'm moving at light speed, what do I see?" are unanswerable:
 http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/headlights.html

(Or indeed refer to any any textbook covering the postulates of special relativity, since the postulates implicitly preclude dealing with light-speed reference frames).

Since you disagree with these sources, could you provide counter-references of your own, Sciconoclast?
 

Offline jeffreyH

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Re: What happens when time slows down at light speed?
« Reply #35 on: 07/03/2014 02:22:49 »
Justin:
           Your comment that time stops at the speed of light according to relativity is correct despite some of the comments such as you can't make such blanket statements.  Einstein made them.

Since we're a science forum and simply stating your opinion doesn't make it true, here's some arguments that show you cannot, indeed, move at light speed and asking about "If I'm moving at light speed, what do I see?" are unanswerable:
 http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/headlights.html

(Or indeed refer to any any textbook covering the postulates of special relativity, since the postulates implicitly preclude dealing with light-speed reference frames).

Since you disagree with these sources, could you provide counter-references of your own, Sciconoclast?

This is always a very difficult subject to debate. Although light has a wavelength and can be shifted it preserves its information content over vast distances. Otherwise it could not be used to determine the composition of stars, planets etc. So while one aspect of light, the wavelength, is a variable the informational content is fixed until observed, absorbed or reflected. With reflection the informational content is necessarily changed due to the change in the composition of the light. This fixation of information content could be argued to be via time dilation but that could never be proven anyway.
 

Offline JP

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Re: What happens when time slows down at light speed?
« Reply #36 on: 07/03/2014 15:21:27 »
Justin:
           Your comment that time stops at the speed of light according to relativity is correct despite some of the comments such as you can't make such blanket statements.  Einstein made them.

Since we're a science forum and simply stating your opinion doesn't make it true, here's some arguments that show you cannot, indeed, move at light speed and asking about "If I'm moving at light speed, what do I see?" are unanswerable:
 http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/headlights.html

(Or indeed refer to any any textbook covering the postulates of special relativity, since the postulates implicitly preclude dealing with light-speed reference frames).

Since you disagree with these sources, could you provide counter-references of your own, Sciconoclast?

This is always a very difficult subject to debate. Although light has a wavelength and can be shifted it preserves its information content over vast distances. Otherwise it could not be used to determine the composition of stars, planets etc. So while one aspect of light, the wavelength, is a variable the informational content is fixed until observed, absorbed or reflected. With reflection the informational content is necessarily changed due to the change in the composition of the light. This fixation of information content could be argued to be via time dilation but that could never be proven anyway.

It's not really a hard topic to debate at all if you're precise about things.  The problem is that we're arguing on the internet, rather than debating based on science, so posters can say what they "feel" is correct based on a misunderstanding of what relativity says rather than drilling down precisely into details.  When I first learned relativity, I had the same misunderstandings, so I can't fault anyone for it.

The hard fact is that we cannot define a reference frame in special relativity that is traveling at light speed.  So describing what a photon "experiences" as we would do for an observer with mass is meaningless.  We simply don't have a theory or model that covers it. 

What we can say, as you point out, is that photons appear to not decay as massive particles would, so in a sense they don't change their structure over time as other particles with mass do.  Furthermore, particles like neutrinos can change their flavor, but would not be able to do so if they had no mass.  So in that sense, masslessness is tied to static behavior of the particles.  But in a very obvious way, photons aren't static--they are created and destroyed. 
 

Offline sciconoclast

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Re: What happens when time slows down at light speed?
« Reply #37 on: 08/03/2014 01:24:09 »
JP; we may be miss-reading each others comments.

I assumed that when Justin stated, "while moving at speeds near that of light time passes slower" he was including the possibility of a physical observer; but, when he stated, "and stops at the speed of light" he was only referring to energy that is capable of the speed of light.  When I stated that he was correct that time stops at the speed of light I was not implying that a physical observer could experience that.

There is nothing in your reference to disagree with that.  I have never met a physicist  who did not know that according to relativity time changes for an observer as velocity changes, that the speed of light is universal, that time is frozen at the speed of light, and that matter cannot reach the speed of light [ usually this is stated as matter having to obtain infinite mass - I think your reference stating that infinite accelerating energy is required is basically saying the same thing ]. 

As for time being frozen at the speed of light here is a quote from Brian Green in Special Relativity in a Nut Shell. "Because motion through both time and space must always add up to the speed of light, when an object (such as a photon) moves through space at light speed, Einstein reasoned, there's no room for motion and time, consequently, stops."          www.pbs.org/wgbh/nova/physics/special-relativity-nutshell.html

 

Offline JP

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Re: What happens when time slows down at light speed?
« Reply #38 on: 08/03/2014 03:22:56 »
I'm not misreading you, Sciconoclast.  Science can only talk about what we, as massive observers, can access via experiments.  Saying that time is frozen at the speed of light is ambiguous at best and probably meaningless.  Because we, nor any observer, nor our experimental apparati can take measurements from the point of view of a photon (or other light-speed entity), we can't measure time (or distance) from its point of view.  We can talk about how we as massive observers experience photons and say some thing about photons from that perspective.

If we do make the mistake of thinking that time stops for a photon at light speed as we'd assume by naively applying the equations of special relativity, we end up with a paradox--we as massive observers DO see photons changed.  They can be emitted and absorbed, for example.  But if photons experience no time, how can they ever be emitted and absorbed? 

What Brian Greene seems to be doing in that post is to define clock measurements in terms of a particle's world line.  Unfortunately, in dumbing the science down for a lay article, he's made it somewhat misleading (a problem with a great deal of pop-sci work).  The fact is that however we want to define "time" for photons or other massless particles, it is not the same thing as time experienced by massive particles.  We have to pick a definition precisely and tell others what we mean by that definition. 

Again, as I said in my first post, blanket statements like "photons experience no time" are misleading and fairly meaningless (until we define what we mean by time).
 

Offline jeffreyH

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Re: What happens when time slows down at light speed?
« Reply #39 on: 08/03/2014 10:33:13 »
I'm not misreading you, Sciconoclast.  Science can only talk about what we, as massive observers, can access via experiments.  Saying that time is frozen at the speed of light is ambiguous at best and probably meaningless.  Because we, nor any observer, nor our experimental apparati can take measurements from the point of view of a photon (or other light-speed entity), we can't measure time (or distance) from its point of view.  We can talk about how we as massive observers experience photons and say some thing about photons from that perspective.

If we do make the mistake of thinking that time stops for a photon at light speed as we'd assume by naively applying the equations of special relativity, we end up with a paradox--we as massive observers DO see photons changed.  They can be emitted and absorbed, for example.  But if photons experience no time, how can they ever be emitted and absorbed? 

What Brian Greene seems to be doing in that post is to define clock measurements in terms of a particle's world line.  Unfortunately, in dumbing the science down for a lay article, he's made it somewhat misleading (a problem with a great deal of pop-sci work).  The fact is that however we want to define "time" for photons or other massless particles, it is not the same thing as time experienced by massive particles.  We have to pick a definition precisely and tell others what we mean by that definition. 

Again, as I said in my first post, blanket statements like "photons experience no time" are misleading and fairly meaningless (until we define what we mean by time).

It can be said that the spectrum of light remains unchanged barring any interactions. Time is a problematic concept to apply generally but it is all we have for purposes of measurement.
 

Offline yor_on

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Re: What happens when time slows down at light speed?
« Reply #40 on: 08/03/2014 12:44:23 »
Sorry but "What happens when time slows down at light speed?" is wrong. Time stops for noone. It's observer dependencies, I thought I had made that one clear by the example of three observers at different speed, each one defining different time dilations for the others, noone agreeing with another's local measurements? What is unclear with that example? That time dilations is measurable as in a twin experiment, is a result of 'c', locally giving you a same answer (equilibrium) in each uniformly moving frame of reference, no matter your speed or mass.

As for massless 'photons' they have a speed that is a limit. If a neutrino has a ever so slight rest mass it can't be 'moving' at 'c'. If it could Einstein would be wrong.

Time does not slow down locally.
 

Offline dlorde

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Re: What happens when time slows down at light speed?
« Reply #41 on: 08/03/2014 14:16:00 »
It can be said that the spectrum of light remains unchanged barring any interactions.
A spectrum is the range of frequencies of many photons; it isn't relevant to a discussion of individual photons and how they may or may not experience time.
 

Offline jeffreyH

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Re: What happens when time slows down at light speed?
« Reply #42 on: 08/03/2014 15:36:45 »
It can be said that the spectrum of light remains unchanged barring any interactions.
A spectrum is the range of frequencies of many photons; it isn't relevant to a discussion of individual photons and how they may or may not experience time.

All the photons making up the spectrum remain unchanged. Sorry for not being specific enough. I thought that was a given.
 

Offline dlorde

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Re: What happens when time slows down at light speed?
« Reply #43 on: 08/03/2014 17:03:21 »
All the photons making up the spectrum remain unchanged. Sorry for not being specific enough. I thought that was a given.
OK - I see what you mean - but why would any photon change without an interaction, and don't photon interactions involve absorption and re-emission (i.e. a 'new' photon emerges) ? I'm struggling to see what your point is - I'm not well up on this stuff...
 

Offline jeffreyH

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Re: What happens when time slows down at light speed?
« Reply #44 on: 08/03/2014 23:39:27 »
All the photons making up the spectrum remain unchanged. Sorry for not being specific enough. I thought that was a given.
OK - I see what you mean - but why would any photon change without an interaction, and don't photon interactions involve absorption and re-emission (i.e. a 'new' photon emerges) ? I'm struggling to see what your point is - I'm not well up on this stuff...

They remain unchanged when they don't interact, when they leave a distant star and reach a telescope they have avoided collisions all the way along their path.
 

Offline dlorde

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Re: What happens when time slows down at light speed?
« Reply #45 on: 09/03/2014 00:08:31 »
They remain unchanged when they don't interact, when they leave a distant star and reach a telescope they have avoided collisions all the way along their path.
That was my point; I wondered why it was necessary to say that...

I don't suppose it matters.

« Last Edit: 09/03/2014 00:10:42 by dlorde »
 

Offline sciconoclast

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Re: What happens when time slows down at light speed?
« Reply #46 on: 09/03/2014 01:44:22 »
JP; you have not yet provided a reference stating that time does not stop at the speed of light.  It only provided an explanation for why things with mass cannot achieve the speed of light and a biographers note on Einsteins musings from before he came to relativity.

Technically, a better wording would be that the value for light in the fourth dimension is always zero.

As for the reference I gave as being simplified, I looked especially for a simple explanation.  Based on the e-mail that you sent me some time ago, as to why this was not a good forum to introduce my recent experiments, I thought that this is the kind of reference that you wanted. It was easy to understand and in agreement with the more complicated mathematical explanations that I have seen.
 
"Every thing should be as simple as possible, but not simpler", Albert Einstein.
"If you can't explain your theory so that a bar tender can understand it, then it is probably wrong", I think this was by Maxwell but it may have been one of the others.

It may be that the emission absorption contradiction that you mentioned may be because we have dumbed down and are talking about particles and photons and speed.  This may help: "Sense  the theory of general relativity implies the representation of physical reality by a continuous field, the concept of particles or material points cannot play a fundamental part, nor can the concept of motion", Albert Einstein, Metaphysics of Relativity, 1950.

What Einstein actually proposed is not in question whether or not he was completely correct is.
 

Offline jeffreyH

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Re: What happens when time slows down at light speed?
« Reply #47 on: 09/03/2014 11:44:27 »
JP; you have not yet provided a reference stating that time does not stop at the speed of light.  It only provided an explanation for why things with mass cannot achieve the speed of light and a biographers note on Einsteins musings from before he came to relativity.

Technically, a better wording would be that the value for light in the fourth dimension is always zero.

As for the reference I gave as being simplified, I looked especially for a simple explanation.  Based on the e-mail that you sent me some time ago, as to why this was not a good forum to introduce my recent experiments, I thought that this is the kind of reference that you wanted. It was easy to understand and in agreement with the more complicated mathematical explanations that I have seen.
 
"Every thing should be as simple as possible, but not simpler", Albert Einstein.
"If you can't explain your theory so that a bar tender can understand it, then it is probably wrong", I think this was by Maxwell but it may have been one of the others.

It may be that the emission absorption contradiction that you mentioned may be because we have dumbed down and are talking about particles and photons and speed.  This may help: "Sense  the theory of general relativity implies the representation of physical reality by a continuous field, the concept of particles or material points cannot play a fundamental part, nor can the concept of motion", Albert Einstein, Metaphysics of Relativity, 1950.

What Einstein actually proposed is not in question whether or not he was completely correct is.

Can you elucidate the emission absorption contradiction as if explaining it to a bar tender? I would like to know more.
 

Offline sciconoclast

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Re: What happens when time slows down at light speed?
« Reply #48 on: 09/03/2014 12:48:26 »
Einstein and Bohr only agreed on a few things.  One of them was that reality is only mathematical probability fields that governed where and when things actualize.  The probability for a photon's incorporation into an electron or its existence outside of it are already present in the quantum field and occur when the probability is greatest. I am not the best person to explain this because I am not a true believer.

"The field thus becomes an irreducible element of physical description.....The particle can only appear as a limited region of space in which the field strength or the density are particularly high." Albert Einstein.

"Einsteins Relativity is a Theory of posteriori Effects not a priori causes..." from Geoff Hasehurst on Time and Reality.

I am also troubled by suggestion that we as massive observers cannot contemplate things from the viewpoint at the speed of light.   The reference sight that JP listed reveals that Einstein was attempting this at a very early age.  This of course continued throughout his life.  The most famous of these mind experiments was when he was on a bus traveling away from a clock on a building and how the information from the clock would be frozen if the bus was traveling at the speed of light.  It is not famous because it is a good representation of relativity but because it led him to relativity.

"The true sign of intelligence is not knowledge but imagination." Albert Einstein.
"Imagination is more important than knowledge". Albert Einstein
 

Offline Ethos_

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Re: What happens when time slows down at light speed?
« Reply #49 on: 09/03/2014 14:22:24 »


"The true sign of intelligence is not knowledge but imagination." Albert Einstein.
"Imagination is more important than knowledge". Albert Einstein
Excellent quote my friend! It might be good for our cookie cutter scientists of today to start using a little of this vanishing quality!
 

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Re: What happens when time slows down at light speed?
« Reply #49 on: 09/03/2014 14:22:24 »

 

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