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Author Topic: A light paradox?  (Read 3021 times)

Offline MikeS

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A light paradox?
« on: 12/05/2012 15:39:35 »
If photons do not experience either time or distance how is it possible for light to be a wave?


 

Offline Pmb

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Re: A light paradox?
« Reply #1 on: 12/05/2012 16:07:29 »
If photons do not experience either time or distance how is it possible for light to be a wave?
Hard to say unless it is known what your understanding of the wave-particle duality is and unless it is known what your understanding of the meaning of uncertainty is.
 

Offline JP

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Re: A light paradox?
« Reply #2 on: 12/05/2012 16:10:03 »
There is no scientific theory that says that "photons do not experience either time or distance."  So you're starting from a flawed premise here. 

Since the premise doesn't hold, there is no paradox.


Edit: In fact, we know they experience both time and distance.  If I shoot a photon at a distant observer, it takes time to cover that distance.  We can measure that (hence measuring distances to distant stars in light years).  We also know that light behaves like a wave, and have been able to experimentally detect its wavelike behavior since the early 1800s. 
« Last Edit: 12/05/2012 16:14:40 by JP »
 

Offline Pmb

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Re: A light paradox?
« Reply #3 on: 12/05/2012 16:36:17 »
Edit: In fact, we know they experience both time and distance.  If I shoot a photon at a distant observer, it takes time to cover that distance.  We can measure that (hence measuring distances to distant stars in light years).
That means that we can measure said time interval. Since a photon can't carry a clock it implies that photons cannpt measure that time interval. I'm using "measure" in place of experience.
We also know that light behaves like a wave, and have been able to experimentally detect its wavelike behavior since the early 1800s. 
I don't follow.It was Newton who studied interference rings in 1717
http://en.wikipedia.org/wiki/Newton's_rings

If one observes interference then one is experience wave phenomena.
 

Offline Geezer

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Re: A light paradox?
« Reply #4 on: 12/05/2012 18:21:31 »
Of course, when it's a wave, it's not really an "it" at all. If I understand correctly (which I probably don't!), light only takes on particle-like behavior when it interacts with matter.

I can't remember if I asked this before, but is it possible to reproduce the particle experiments using radio frequencies, or do the scales and available detectors prevent that?
 

Offline JP

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Re: A light paradox?
« Reply #5 on: 12/05/2012 18:45:36 »
Edit: In fact, we know they experience both time and distance.  If I shoot a photon at a distant observer, it takes time to cover that distance.  We can measure that (hence measuring distances to distant stars in light years).
That means that we can measure said time interval. Since a photon can't carry a clock it implies that photons cannpt measure that time interval. I'm using "measure" in place of experience.
We also know that light behaves like a wave, and have been able to experimentally detect its wavelike behavior since the early 1800s. 
I don't follow.It was Newton who studied interference rings in 1717
http://en.wikipedia.org/wiki/Newton's_rings

If one observes interference then one is experience wave phenomena.

Good point.  Of course, Newton rejected the wave theory of light and explained it as particles (it would be interesting to find out how he explained those fringes with particles...)  The early 18th century was when a rigorous wave theory of light was proposed and tested (Young's two slit experiment being the major experimental milestone.)
 

Offline Pmb

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Re: A light paradox?
« Reply #6 on: 12/05/2012 19:52:45 »
Of course, when it's a wave, it's not really an "it" at all.
It isn't a particle. It isn't a wave. It's something else. That's the weird part about it. Consider the double slit experiment again. Suppose you have a source of light which is very weak, that when the beam hits the screen it hits one photon at a time and when it does that you see a single blip on the screen. That one blip is located with a small region of space on the screen. That is the particle part of QM. If one were to record where every single blip hit the screen and then recorded it later then ploted them out on a screen then what you'd see is a patter form. That pattern has a wave shape to it. That's where the wave part of QM. Who do you imagine is the one who experiences the wave-particle duality part of it?
 

Offline MikeS

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Re: A light paradox?
« Reply #7 on: 13/05/2012 07:36:05 »
There is no scientific theory that says that "photons do not experience either time or distance."  So you're starting from a flawed premise here. 



JP

My statement above was based up what I understand as part of GR. 

Light travels at the null point of time.  At the speed of light time ceases to pass for a photon (or anything).  At the speed of light distance in the direction of travel shrinks to zero.

Would you please clarify what mainstream does consider being the correct premise?
 

Offline JP

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Re: A light paradox?
« Reply #8 on: 13/05/2012 14:57:10 »
Mike, the big problem is that special and general relativity are derived by considering reference frames that always move at less than the speed of light.  You can never talk about something moving at the speed of light since the theory doesn't work for those objects.  You can only describe space and time for things going close to, but less than the speed of light.

The reason for this is that one of the postulates of relativity is that  the speed of light is the same for all observers.  If you violate this assumption, the whole theory breaks down and you'd need to come up with a new one.  The problem is that light is obviously not moving at the speed of light with respect to itself, so relativity breaks down as a theory when you try to apply it to the point of view of light itself. 
 

Offline MikeS

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Re: A light paradox?
« Reply #9 on: 16/05/2012 08:24:05 »
Mike, the big problem is that special and general relativity are derived by considering reference frames that always move at less than the speed of light. You can never talk about something moving at the speed of light since the theory doesn't work for those objects.  You can only describe space and time for things going close to, but less than the speed of light.

The reason for this is that one of the postulates of relativity is that  the speed of light is the same for all observers.  If you violate this assumption, the whole theory breaks down and you'd need to come up with a new one.  The problem is that light is obviously not moving at the speed of light with respect to itself, so relativity breaks down as a theory when you try to apply it to the point of view of light itself. 

The reasoning seems to be a photons do not have a reference frame as reference frames require rulers and time both of which are meaningless to a photon.  So, by definition a photon does not have a reference frame.  As a photon does not have a reference frame we cannot apply GR time dilation and length contraction to it.  Therefore, “There is no scientific theory that says that "photons do not experience either time or distance”.  This is a circular argument.

This is true for objects with mass but not for light.  Therefore , you can not apply the argument to light.

As an observer can not travel at the speed of light there is no observer.  Therefore, you can not consider there to be an observer.  So does the theory break down?

Light has no reference frame.  Therefore you can not consider it to have a reference frame.  So does the theory break down?

The argument that “There is no scientific theory that says that photons do not experience either time or distance” is based on a circular argument, so it can be ignored.  Therefore, I would argue that there is a theory that says “photons do not experience either time or distance”, that theory is GR.

I am just interested in what is real as opposed to being open to interpretation.
« Last Edit: 16/05/2012 08:40:10 by MikeS »
 

Offline JP

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Re: A light paradox?
« Reply #10 on: 16/05/2012 12:57:27 »
The argument that “There is no scientific theory that says that photons do not experience either time or distance” is based on a circular argument, so it can be ignored.  Therefore, I would argue that there is a theory that says “photons do not experience either time or distance”, that theory is GR.

Mike, we've had similar posts from you many times before.  It may not make you happy that no one's come up with a testable theory for a photon's reference frame, but that's how special and general relativity work.

If you want to propose speculative new physics, please do so in the New Theories forum.  In the meantime, stop misleading posters by promoting your own views on how general relativity works.  You are very wrong about it.
 

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Re: A light paradox?
« Reply #10 on: 16/05/2012 12:57:27 »

 

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