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Author Topic: Does ' Light ' wear out ?  (Read 6600 times)

Offline neilep

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Does ' Light ' wear out ?
« on: 03/10/2005 13:50:42 »
Hi Everybody, I'm Neil,

Is it possible that the Universe is older that we think it is ?

We use light to age it yes ?...well, is it possible for light to wear out ?..could the Universe be a lot lot older than it is, because someone hasn't chganged the Universal light bulb ?

Thanks



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Offline Solvay_1927

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Re: Does ' Light ' wear out ?
« Reply #1 on: 07/10/2005 01:35:24 »
Neil,
I imagine nobody's replied to this yet because ... well ... we don't have a clue what you're saying.

What makes you think that light might "wear out"?

Do you ever sign on under the pseudonym "Tianman"?

;)

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Offline neilep

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Re: Does ' Light ' wear out ?
« Reply #2 on: 07/10/2005 01:53:13 »
That's ok..I don't know what I mean either!..but like water evaporates into a gas which then disperses , could something similar happen to light ?.....

yours

Tianman...err  neil !!....

Incidentally, why ask if I'm Tianman ?....is it because of the above question ?

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Offline Solvay_1927

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Re: Does ' Light ' wear out ?
« Reply #3 on: 07/10/2005 02:06:59 »
Just a joke - I read your question and got so confused that I thought I was reading one of tianman's postings.

(Sorry tianman. [V])


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Offline itsjustme

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Re: Does ' Light ' wear out ?
« Reply #4 on: 07/10/2005 02:21:44 »
it is possible by my theory. my theory states that photons have mass (light molecules are photons) wich means that they have to get slower just because they have mass. even if my theory is incorrect then the amplitude of the light does get smaller and smaller as it goes along. just like if you drop a stone in a pond.
 

Offline gsmollin

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Re: Does ' Light ' wear out ?
« Reply #5 on: 08/10/2005 01:00:13 »
Since light travels at the speed of light, then it does not age. Photons don't wear out because even the ones from the CBR are now at age 0.

"F = ma, E = mc^2, and you can't push a string."
 

Offline ukmicky

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Re: Does ' Light ' wear out ?
« Reply #6 on: 08/10/2005 01:59:22 »
Light dosen't age,that makes so much sense.

Because it travels at the speed of light where time stands still it can't, it so obvious.and yet i didnt know.
 
In future if someone had asks me how old the light reaching us from Alpha Centauri is,i will confuse them and say 0 light years instead of 4.22 light years old. :)




Michael                                      
« Last Edit: 08/10/2005 03:15:24 by ukmicky »
 

Offline neilep

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Re: Does ' Light ' wear out ?
« Reply #7 on: 08/10/2005 04:16:28 »
Well I tell you something...I'm bloody worn out !!

Gsmollin, what happens to the bit of light that hits my eyes after I've seen it ?...well, I suppose one could also ask what happens to any light once it hits an object ?

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Offline itsjustme

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Re: Does ' Light ' wear out ?
« Reply #8 on: 08/10/2005 08:39:19 »
light does not age because of time dilation, you will understand why if you understand einstein's special relativity theory. light years are just the measure of distance in space 1 light year means that light will take 1 year to travel from one point to the other. if you were traveling at the speed of light you would not age. at 99.95% the speed of light you can travel 1000 light years and come back and you would of only aged 10 years while the earth would of age a lot more. photons do not age but as light travels it loses amplitude.
« Last Edit: 08/10/2005 08:40:31 by itsjustme »
 

Offline gsmollin

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Re: Does ' Light ' wear out ?
« Reply #9 on: 08/10/2005 19:23:55 »
quote:
Originally posted by neilep

Well I tell you something...I'm bloody worn out !!

Gsmollin, what happens to the bit of light that hits my eyes after I've seen it ?...well, I suppose one could also ask what happens to any light once it hits an object ?

Men are the same as women.... just inside out !!



Once it interacts with other matter, it is changed into something else. In your eye, the energy of the photon causes an electrochemical reaction in your eye.

"F = ma, E = mc^2, and you can't push a string."
 

Offline gsmollin

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Re: Does ' Light ' wear out ?
« Reply #10 on: 29/10/2005 16:17:54 »
quote:
Originally posted by itsjustme

light does not age because of time dilation, you will understand why if you understand einstein's special relativity theory. light years are just the measure of distance in space 1 light year means that light will take 1 year to travel from one point to the other. if you were traveling at the speed of light you would not age. at 99.95% the speed of light you can travel 1000 light years and come back and you would of only aged 10 years while the earth would of age a lot more. photons do not age but as light travels it loses amplitude.



"Loss of amplitude" is another way of saying that photons do interact with matter on their way across space. If a photon encounters a particle of matter equal-to-or-greater than its wavelength, it can be absorbed or scattered. Gasses also have an ability to absorb certain wavelengths of radiation, especially UV, which is how emission nebulae glow so beautifully in visible light. Without matter to affect its course, a photon of EM radiation will not age, and retains its identity throughout the age of the universe. This fact allows astronomers to look back in time, and reconstruct the story of the universe, all the way to the CBR at age ~300k years. Before that, the universe was so hot that it was ionized, and was opaque to radiation. So that is the limit for EM studies.

I wonder if there is a gravitational background that could be probed, even further.

"F = ma, E = mc^2, and you can't push a string."
« Last Edit: 29/10/2005 16:28:13 by gsmollin »
 

Offline McQueen

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Re: Does ' Light ' wear out ?
« Reply #11 on: 30/10/2005 06:48:59 »
quote:
Originally posted by Solvay_1927

Neil,
I imagine nobody's replied to this yet because ... well ... we don't have a clue what you're saying.

What makes you think that light might "wear out"?

Do you ever sign on under the pseudonym "Tianman"?


Just take a flashlight (torch) out on a dark night!
 

Offline Solvay_1927

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Re: Does ' Light ' wear out ?
« Reply #12 on: 31/10/2005 20:36:20 »
quote:

Hi Neil (Yan)

The universe is as old as it is. You are right where you are and nowhere else as far as you're concerned. You are not made of photons that will disperse in a fluffy magic cloud.
Men are not the same as women... just inside out, even though you chopped your own dick off because Andigarimisou told you to.
You are an icchantikka Greek pervert, and none of you is going to escape from the dreadful fate which befalls beings such as you.
Whilst I applaud human efforts to understand the world in scientific terms, it's karma and rebirth all the way.

Have a nice day.



Eh?????


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Offline ukmicky

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Re: Does ' Light ' wear out ?
« Reply #13 on: 31/10/2005 20:46:06 »
I must admit DOUGHNUTS  reply did get me wondering.

Michael                                      
 

Offline Solvay_1927

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Re: Does ' Light ' wear out ?
« Reply #14 on: 31/10/2005 21:09:57 »
Has anyone offered him medication?

(Or is the problem that he needs to REDUCE his dosage?)


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Offline Simmer

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Re: Does ' Light ' wear out ?
« Reply #15 on: 06/11/2005 18:22:07 »
Quite!  What does he mean by calling neilep a conscienceless spreader of negative karma?  That's my job! :D
 

Offline Atomic-S

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Re: Does ' Light ' wear out ?
« Reply #16 on: 21/11/2005 06:37:02 »
Methinks that the question of light aging is answered by two laws of nature: Conservation of energy, and the Second Law of Thermodynamics. The first tells us that the energy cannot be lost. The second tells us that the energy can, however, be disorganized if given the opportunity. That would be like when it collides with other matter, being absorbed and turned into other forms of energy, possibly to be re-radiated as a longer-wavelength, more disorganized form. However, in the absence of such intervening matter, I am aware of no principle that allows light to degrade, except simply the inverse square law whereby it spreads over greater volumes -- achieving, however, increased collimation in the process, so that its overall information value remains unchanged.
 

Offline DoctorBeaver

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Re: Does ' Light ' wear out ?
« Reply #17 on: 21/11/2005 08:57:14 »
quote:
The first tells us that the energy cannot be lost.


Yes it can. I've got far less energy now than I had when I was young! :D

On a more serious note - what would be result of 2 photons colliding head-on? As they would have identical momentum & energy, would they just stop dead, merge, annihilate, turn into something else, or what?
 

Offline Solvay_1927

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Re: Does ' Light ' wear out ?
« Reply #18 on: 21/11/2005 22:24:57 »
I'm not absolutely 100% sure, but I think that 2 photons can't collide - they'd each just carry on their merry way as if the other doesn't exist.

It's because photons are bosons (i.e. particles of integer spin), and obey Bose-Einstein statistics, which means that two (or three, or an infinite number of) photons can occupy the same space.  Whereas fermions (with half-integer spin, e.g. electrons, protons, neutrons and their antiparticles) obey Fermi-Dirac statistics, which means that two of them in the same state (of spin, etc.) can't occupy exactly the same region of space, so they collide/merge/annihilate/whatever.

OK, OK, so I don't really understand what I'm talking about, I'm just trying to sound clever!

Are there any real physicists out there who can answer this?  (Where's gsmollin &co when you need them?)


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Re: Does ' Light ' wear out ?
« Reply #18 on: 21/11/2005 22:24:57 »

 

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