Date: Thu Oct 22 22:08:07 1998
Posted by Ricky J. Sethi
Supposedly, time slows down as you approach the speed of light.
Therefore, does time exist for a photon? When a photon leaves
a transitioning electron, does time not pass for the photon until
it is absorbed by another electron (maybe Billions of our years
later) at which point it ceases to exist.
Sorry - entered all my questions in the wrong area of science....
Hello Dr. Frankart,
Yes, it is very much as you suppose... time, the way we conceive of
it, at least, does not pass for the photon. To the photon, the
universe "appears" infinitely tiny. However, there is a trap in
thinking of a photon's "existence" in terms of our own macroscopic
existence (which is, after all, a necessary bias on our part). This
is a very good question but, despite it's undeniable fascination, is
also, in a way, unanswerable because the photon cannot be subjected to
our experiences. I'm basically reiterating what others have
articulated better, so I'll defer to them now. I'm including two of
the online sources below (a previous madsci answer and a link to the
Relativity FAQ). In addition, there are numerous books available on
this subject that address this very idea... a few good ones are, in
order of increasing detail:
- Mr. Tompkins in Paperback by George Gamow: an EXCELLENT
book that's incredibly fun to read,
- Mould's Basic Relativity: a general introductory book on
Relativity for undergrads, and
- D'Inverno's Introducing Einstein's Relativity: a very nice
- Here is an excerpt from a previous MadSci answer that can be
- II. A photon does not experience its own existence. To a photon
the moment of its creation is the moment of its annihilation and all
distances in the universe are equal to zero from every point to every
other point - hence, to a photon, the universe is still infinitely
small... Like it was when it was created. Remember: everything in the
universe is ultimately made of waveforms of some sort.
- And here is an excerpt from the Relativity
- Sometimes people persist: What would the world look like in the
reference frame of a photon? What does a photon experience? Does space
contract to two dimensions at the speed of light? Does time stop for a
photon? .... It is really not possible to make sense of such questions
and any attempt to do so is bound to lead to paradoxes. There are no
inertial reference frames in which the photon is at rest so it is
hopeless to try to imagine what it would be like in one. Photons do
not have experiences. There is no sense in saying that time stops when
you go at the speed of light. This is not a failing of the theory of
relativity. There are no inconsistencies revealed by these
questions. They just don't make sense.
- Despite these empty answers, nobody should feel too put down for
asking such questions. They are exactly the kind of question that
Einstein often asked himself from the age of 16 until he discovered
special relativity ten years later.
Well, I hope this helps... if you have any further questions or would
like any clarifications, please drop me a line at firstname.lastname@example.org and I'll
be more than happy to go into this in more detail.
For more information on Physics, try the
in the MadSci Library
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