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Author Topic: Does light travel forever?  (Read 3691 times)

Offline colarris

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Does light travel forever?
« on: 03/05/2013 21:03:22 »
Can light travel forever? The light reflected from me, will it travel off into space for infinity?
« Last Edit: 03/05/2013 22:41:00 by chris »


 

Offline Pmb

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Re: Does light travel forever?
« Reply #1 on: 03/05/2013 23:16:39 »
Can light travel forever? The light reflected from me, will it travel off into space for infinity?
There are photons arriving at the eath today which were released shortly after the big bang which was about 14.5 billion years ago. Light reflected from you travels through the atmosphere and goes through a process of absorption and re-emssion. In one the sense of the waves that leave your body, some of it, if you're outside, will reach space and travelt forever. In the sense of the photons leaving your body I would imagine that they all get absorbed and re-emitted so in that sense they don't, but copis of them due.
 

Offline evan_au

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Re: Does light travel forever?
« Reply #2 on: 04/05/2013 10:45:39 »
Some photons bouncing off you now could continue indefinitely - but other photons will be absorbed by the walls in the room you are in, or get reflected by clouds back down to Earth and absorbed....

The photons that travel the longest will get red-shifted by the expansion of the universe until they are no longer visible light, but become infra-red or microwaves.
 

Offline yor_on

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Re: Does light travel forever?
« Reply #3 on: 04/05/2013 22:20:05 »
You can define such as all light ever existing, should be able to reach us at some point, unless there are some barrier quenching or otherwise hiding it from our measurements. That's why we can see those most distant galaxies, because of the light informing us of them
=

There are two ways I know light won't reach us, from main stream definitions. One is space expanding, and accelerating, 'faster than light' meaning that light won't be able to cross that space, as it has finite 'speed'. The other is the 'curtain of light' hiding the earliest effects from a Big Bang, before rest mass particles and matter came into existence. Of the top of my head that is, there might be more effects.
« Last Edit: 04/05/2013 22:25:29 by yor_on »
 

Offline dlorde

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Re: Does light travel forever?
« Reply #4 on: 05/05/2013 21:30:54 »
... there might be more effects.

Blocking by gas and dust?
 

Offline CliffordK

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Re: Does light travel forever?
« Reply #5 on: 06/05/2013 06:42:16 »
Don't forget the inverse square law, where the intensity of the light is proportional to the inverse of the square of the distance.

Thus, the farther one goes, the less light that gets to the viewer.
 

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Re: Does light travel forever?
« Reply #5 on: 06/05/2013 06:42:16 »

 

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