How a photon experiments time

1. Jan 3, 2004

Tachyon son

These are sentences Ive red regarding this subject:

- Time doesn´t flow for a photon travelling at c.
- There is no after neither before for it.
- Therefore, no causes and effects.
- A photon doesnt have age, it doesn´t matter if it was born in Big Bang or in a experiment yesterday.

So, how does it "experiment" time? And how does thermodynamics and entrhopy affect it if the time is not running for it?
Any chance of describing the (impossible) experience of a human travelling at c?

Thanks for the explanation. Im quite curious, but mentally unable to learn maths and technical physics...

2. Jan 4, 2004

tenzin

Good question

I think before we answer the question we need to define time. For me the most general definition of time is change. If we measure the time between two events we are measuring the number of occurences of a particular event that happened between the two events. These occurences could be ticks on a second hand or oscilations of an atomic clock. Either way, what is being measured here is change, something that is constantly moving. Therefore if something experiences time it must be changing and vice versa. From this logic it is impossible for something to not experience time and also be produced, abide and then disintegrate. How could we talk about the lifetime of a photon without the idea of the photon experiencing time.

I would encourage you to not be discouraged in trying to understanding physics from a more techincal view. From my own personal experience the most important factor in gaining understanding is the desire to know. In fact, something the people who are really good at the technical aspect loose sight of the interpretation. It is sometimes better to have one foot in the ocean and one on the shore.

3. Jan 5, 2004

Tachyon son

Im still quite confused

I understand what you mean tenzin, obviously everything suffer changes, so I suppose everything is affected by time. Its a matter of reference frame then (the photon sees our clocks running very fast)?

Quoted from Gribbin´s "Schrodinger´s kittens":
The Lorentz transformations tell us that time stands still for an object moving at the speed of light. From the point of view of the photon, of course, it is everything else that is rushing past at the speed of light. And under such extreme conditions, the Lorentz-Fitzgerald contraction reduces the distances between all objects to zero. You can either say that time does not exists for an electromagnetic wave, so that it is everywhere along its path (everywhere in the Universe) at once; or you can say the distance does not exist for an electromagnetic wave, so that it "touches" everything in the Universe at once.

Im confused when he says "...the Lorentz-Fitzgerald contraction reduces the distances between all objects to zero...you can say the distance does not exist for an electromagnetic wave."

If a photon needs about 8 min to travel from Sun to Earth, why does he say that? [?] [?] [?] What happens with that REAL 150.000.000 kilometers?

4. Jan 5, 2004

tenzin

Good quote from that book. This is the problem with some of the arguments here. First off they are saying that there is no such thing as a rest frame for a photon. Then they say that a photon experiences no passage of time and all distances are zero. Now how can be make measurements of space and time from the photon's perspective if there is no reference frame associate with the photon's rest frame?