The Naked Scientists

The Naked Scientists Forum

Author Topic: Lifetime of Photons  (Read 3804 times)

Offline science_guy

  • Hero Member
  • *****
  • Posts: 701
  • I'm right there... inside neilep's head!
    • View Profile
Lifetime of Photons
« on: 11/09/2006 16:19:38 »
Do Photons have a Certain amount of time before they burn out or quit?  For example, If we were able to hold a photon to be travelling at our speed, how long would it take to die?

If Photons could die, than perhaps there reaches of space that we cannot possible see, because they are so far away that the photons die before they can reach us.  What scientists may have identified as the edge of the universe may only be the limit of how far photons can travel.  The universe could even be infinite!

Keep in mind that im taking relativity into account, so it would take much longer in space for the photon to die while travelling in space than being held at our speed.

_________________________________________________________________________________________

I would engage you in a battle of wits, but it is against my moral code to attack the unarmed.


 

Offline lightarrow

  • Neilep Level Member
  • ******
  • Posts: 4586
  • Thanked: 7 times
    • View Profile
Re: Lifetime of Photons
« Reply #1 on: 11/09/2006 19:52:06 »
I'm sorry we could never be able to "hold a photon to be travelling at our speed", the speed of light (C) doesn't depend on the reference frame. For this reason we write "C" as a constant.

If you are in A going to B with a speed v = 0.999999999999999999C and a laser beam is fired from A to B in the exact moment you pass by A, you will see it at the same speed c.

I know, it seems a paradox. Infact, from this only follow all the strange things about relativity, for example the relativity of simultaneity, the twin paradox and a lot of other things.

The fact is that we have chosen a "bad" definition of speed, when we have chosen v = S/t, since space and time are not actually independent from each other; but we didn't know it!

If we defined the speed of a body in a more appropriate way, that is, exactly in the way we define lenght, mass, time, that is, using a sample of it and adding  n equal samples to make a sample n-times bigger, it's possible to show, mathematically, that the speed of light would become infinite!

For this reason it's impossible to reach the speed of light.

The fact that is not infinite, with the definition S/t, is because, said in simple terms, moving at very high speed, you start to move not only through space, but through time also; so the "t" in the formula S/t can never be exactly zero, if S is not zero.

 

Offline Soul Surfer

  • Neilep Level Member
  • ******
  • Posts: 3345
  • keep banging the rocks together
    • View Profile
    • ian kimber's web workspace
Re: Lifetime of Photons
« Reply #2 on: 11/09/2006 23:34:27 »
A photon lasts for ever as long as it does not interact with matter ie get absorbed or deflected.  photons do not interact with each other and only interact with the gravitational field of dark matter by being deflected.

Learn, create, test and tell
evolution rules in all things
God says so!
 

Offline Soul Surfer

  • Neilep Level Member
  • ******
  • Posts: 3345
  • keep banging the rocks together
    • View Profile
    • ian kimber's web workspace
Re: Lifetime of Photons
« Reply #3 on: 11/09/2006 23:35:30 »
A photon lasts for ever as long as it does not interact with matter ie get absorbed or deflected.  photons do not interact with each other and only interact with the gravitational field of dark matter by being deflected.

Learn, create, test and tell
evolution rules in all things
God says so!
 

Offline bostjan

  • Sr. Member
  • ****
  • Posts: 107
    • View Profile
Re: Lifetime of Photons
« Reply #4 on: 12/09/2006 18:44:17 »
If you gave a photon a certain half-life, you would still never see it decay, as it moves at the speed of light always, therefore the internal clock of the photon stands still over any distance.
 

Offline science_guy

  • Hero Member
  • *****
  • Posts: 701
  • I'm right there... inside neilep's head!
    • View Profile
Re: Lifetime of Photons
« Reply #5 on: 13/09/2006 15:51:57 »
so, if the photon is unimpeded, than it could travel an infinite distance?

_________________________________________________________________________________________

I would engage you in a battle of wits, but it is against my moral code to attack the unarmed.
 

Offline lightarrow

  • Neilep Level Member
  • ******
  • Posts: 4586
  • Thanked: 7 times
    • View Profile
Re: Lifetime of Photons
« Reply #6 on: 13/09/2006 17:30:32 »
quote:
Originally posted by science_guy

so, if the photon is unimpeded, than it could travel an infinite distance?
Yes, for what we know now.

Anyway, the universe is expanding, that is, the more you look at distant objects, the more they are going farther from us, and the more light from those objects is red-shifted. This means that, at a certain distance, you can't see them anylonger, that is, the radiation goes out of the visible spectrum, becomes infrared, then microwaves. Infact, there is a cosmic microwave radiation background!
« Last Edit: 14/09/2006 12:44:40 by lightarrow »
 

The Naked Scientists Forum

Re: Lifetime of Photons
« Reply #6 on: 13/09/2006 17:30:32 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums