CAN A PHOTON DIE? IF SO, WHERE DOES IT GO?

[rigney]

I ask such a question simply because I haven't arrived at an answer. I've searched and searched into everything I can imagine and have yet to find anything conclusive. If someone has a viable answer, please let me know?

Edited February 25, 2011 by rigney

[Cap'n Refsmmat]

Photons can be absorbed by atoms. When they do, they give up their energy to the atom; for example, a photon striking a hydrogen atom with the right amount of energy will be entirely absorbed, and its energy will go to boosting the hydrogen's electron to a higher energy level.

[ydoaPs]

Photons cannot die, because they were never alive.

[ajb]

We don't have conservation of photon number in quantum electrodynamics. Energy-momentum of course must be conserved, as is electric charge and spin.

 

So, we have absorption of a photon by an atom which excites the electrons of the atom. You can not on kinematic grounds have a photon just "disappear".

[lemur]

Maybe he means by red-shifting as the photon travels increasingly farther through expanding spacetime. In that case, I would not think the photon would ever terminate unless there is some lower-limit to radio-wave frequency. I would just expect the wavelength to continue growing infinitely.

[rigney]

Photons cannot die, because they were never alive.

 

I honestly liked your answer. So, let me rephrase the question in another manner. Does a radio wave speed up or slow down in frequency over time, or eventually fade into nothingness? And is there anyway to substantiate this as fact? Edited February 26, 2011 by rigney

[Cap'n Refsmmat]

I honestly liked your answer. So, let me rephrase the question in another manner. Does a radio wave speed up or slow down in frequency over time, or eventually fade into nothingness? And is there anyway to substantiate this as fact?

In a vacuum with nothing else going on, a radio wave (or light wave, or whatever else) will just keep going. It will, however, gradually spread out (even a laser beam), until it spreads so wide that you can't even tell it's there. In a conducting medium (or in an atmosphere that scatters radiation), a portion of the wave will be absorbed as it passes through, and it'll die out.

 

As lemur points out, in an expanding universe, the wavelength will gradually get longer (lower frequency), but there's no limit, so it'll just stretch until the wave is unnoticeable by instruments.

[swansont]

I honestly liked your answer. So, let me rephrase the question in another manner. Does a radio wave speed up or slow down in frequency over time, or eventually fade into nothingness? And is there anyway to substantiate this as fact?

 

Changing physical constants can be checked. One does this by looking at dimensionless constants; one often looks at what is called the fine structure constant which includes c — it's a measure of the strength of the electromagnetic interaction. Pretty stringent limits on how much it could have changed have been measured, and include zero (as one might expect).

[rigney]

Changing physical constants can be checked. One does this by looking at dimensionless constants; one often looks at what is called the fine structure constant which includes c — it's a measure of the strength of the electromagnetic interaction. Pretty stringent limits on how much it could have changed have been measured, and include zero (as one might expect).

 

Let me try explaining my thoughts another way. Working with electricity my entire adult life, there are certain anomalies that are strange, yet consistant. For instance, a standard A/C 60 cycle 120V system. Unless the mechanics break down, or we deliberately alter the frequency, electrons in the wire move only fractionally. D.C. is another animal entirely, of which I'm sure you understand. But then, I've never seen an empty (wire) conductor. What if the Higgs boson becomes a factor to begin another chapter in our universe? How do we cope with it? Supposidly the Higgs keeps everything in prospective. A baseball thrown at a 100 mph. A bullet @ 3,300 fps and a rocket, 17,000 + mph. My question is, a photon striking earth at this very instant, is it the same one that left a super nova 13 billion light years ago, a replica, or just giving another photon a boost? Edited February 26, 2011 by rigney

[swansont]

Let me try explaining my thoughts another way. Working with electricity my entire adult life, there are certain anomalies that are strange, yet consistant. Say for instance a standard A/C 60 cycle 120V system. The current swings back and forth at that frequency and doesn't change unless the mechanics break down, or we deliberately alter the system. Eelectrons in the wire move only fractionally. D.C. is another animal entirely, of which i'm sure you know. But then, I've never seen an empty (wire) conductor. What if the Higgs boson become a fact and plays a like part in our universe? How do we cope with it? Supposidly this higgs keeps everything in prospective. A baseba thrown at a 100 mph. A bullet, 3,300 fps and a rocket, 17,000 + thousand mph. My question is, a photon striking earth at this very moment, is it the exact same one that left a super nova 13 billion light years ago, a replica or just giving another photon a boost?

 

Not seeing an empty conductor is pretty easy — current flows in a closed loop. Any electron leaving the conductor is match by one entering. What I can't fathom is how you get from "never seen an empty wire" to the Higgs boson.

 

if the photon didn't interact, it's the same photon. But that doesn't matter, because you couldn't tell the difference between it and another with the same properties. So the answer makes no difference with the physics.

[lemur]

As lemur points out, in an expanding universe, the wavelength will gradually get longer (lower frequency), but there's no limit, so it'll just stretch until the wave is unnoticeable by instruments.

If enough energy was redshifted this much and it tended to re-circulate around existing gravitational fields, could that account for the expansion of the universe? After all, wouldn't there be a great deal of low-frequency energy-waves big enough to slightly shift entire galaxies?

 

 

 

[rigney]

Not seeing an empty conductor is pretty easy — current flows in a closed loop. Any electron leaving the conductor is match by one entering. What I can't fathom is how you get from "never seen an empty wire" to the Higgs boson.

 

As a professional you are likely not to see the humor as this layman does. Over the years it was fun using the empty wire gag, plus Wiggies and Hickeys while working with electrical apprentices. But I'm sure you are more attuned to the Higgs Boson theory. A well thought out theory, but theory nonetheless. Supposedly, we are restricted to light speed due to the Higgs Boson permeating our entire universe. Without it enveloping our world, it seems light speed would be like a walk in the park. If the theory should become factual, what happens then? Do we just write a new book and toss everything else out? Doubtful. But if we find a way around "this barrier", many theories will have to be altered, if not totally scrapped. As a scientist, do you think the Higgs theory has merit?

Edited February 27, 2011 by rigney

[swansont]

As a professional you are likely not to see the humor as this layman does. Over the years it was fun using the empty wire gag, plus Wiggies and Hickeys while working with electrical apprentices. But I'm sure you are more attuned to the Higgs Boson theory. A well thought out theory, but theory nonetheless. Supposedly, we are restricted to light speed due to the Higgs Boson permeating our entire universe. Without it enveloping our world, it seems light speed would be like a walk in the park. If the theory should become factual, what happens then? Do we just write a new book and toss everything else out? Doubtful. But if we find a way around "this barrier", many theories will have to be altered, if not totally scrapped. As a scientist, do you think the Higgs theory has merit?

 

The Higgs is out of my area of study. But AFAIK if it's confirmed, not much changes, since it's predicted by the standard model, so it introduces no new physics beyond the standard model that needs to be explained. Not finding the Higgs has more ramifications than finding it does. But the extent of those ramifications has limits. I don't see how it would affect relativity and light speed, for example. Objects still have mass.