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Frames of reference are identified by the objects which have zero velocity relative to them. A photon cannot have zero velocity, so there is no frame of reference for a photon.

You can tell how much nonsense it is by reading the conclusions of the posters above: that 'time doesn't pass' and 'length is contracted to zero', which are just funny ways of saying spacetime doesn't exist and that's not a position any physicist will take seriously.




So if you are on planet A and want to get to planet B that is 1 lightyear away. You have a magical space ship that can accelerate to c in one minute planet A relative time.

How long does it take to to planet A on the travelers watch. No copping out and saying they've been destroyed by inertia.

I am going to assume it takes one year and and one minute-ish compared to synced clocks in the AB pair.


Your assumption is not supported by another current theories I’m aware of. Our physics doesn’t give any answer to that question - they throw a divide-by-zero error.

The fundamental fact that led Einstein to special relativity is that light in a vacuum appears to be traveling at c regardless of the observer’s frame of reference.

If the observer is a photon, however, it must be able to observe a photon traveling at 0 m/s relatice to it (is, the photon itself). This removes the cornerstone of special relativity and the whole thing comes apart. Using it to make predictions at this point is pointless.

There may be a way to describe the perspective of a photon - we haven’t discovered all of physics yet - but none of our current theories do so.


> You have a magical space ship that can accelerate to c in one minute planet A relative time.

> How long does it take to to planet A on the travelers watch.

You're the one who discovered magic; the answer to this question depends completely on how magic works.

But without magic, it is impossible for an object with mass to accelerate to c. Why do you believe the question has an answer?


We can approach this problem while avoiding all those annoying "you can't"s by considering what would happen if your magical space ship accelerated to almost c in one minute.

The answer is that the distance from A to B would be length-contracted, and would take (from the traveller's point of view) very little time to traverse. In the limit, once the traveller has reached the speed of light, the entire universe in front of them contracts to zero length, and they (from their point of view) can cross the entire universe in no time. Like a photon, they would experience no time between achieving the speed of light, and hitting something.

From the point of view of planet A and B, it still takes a whole year for the traveller to make the journey.


No. Not like a photon. Why do would taking the limit give you an accurate answer?

This is like saying that if you put two protons in exactly the same place they would repel each other with infinite Coulombic force.


Real question: aren’t photons in coherent light in the same frame of reference?

If not, why not?


Based on Retra's earlier comments, the answer to "if not, why not?" is pretty simple -- two photons are not in the same frame of reference because neither photon is in any frame of reference, and therefore there is no frame of reference which both photons are in.

If you were willing to assume that one photon did belong to a frame of reference, you would see that that photon was moving at 0 (impossible, but necessary for it to be part of the frame of reference) and all other photons were moving at c (since the velocity of a photon is c in any inertial frame of reference). Thus, all other photons would not be part of the same frame of reference as the reference photon; no two photons can belong to the same frame of reference.




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