Can light be compressed?

[want to learn]

Can light be compressed?
If light were compressed could it be turned into a solid,gas or liquid?

 

[tablariddim]

It can be concetrated, such as in lasers.. maybe that is a kind of compression?

 

[DaleSpam]

Hi, welcome to SciForums!

This is actually an idea that I played around with for a while. If you had a perfectly reflective material then you could make a box or bottle out of it and you could "store" light in it. Of course, there is no such material, but we can pretend. In any case, if you reduced the size of the box without letting any light "leak out" then you would just get a higher energy density box of light.

At some point I don't know if the energy density would get high enough for particles to form, but even so they would probably form in matter-anti-matter pairs and anihlate back into photons. My quantum mechanics is not strong enough to talk authoritatively about that.

-Dale

 

[James R]

At some point I don't know if the energy density would get high enough for particles to form, but even so they would probably form in matter-anti-matter pairs and anihlate back into photons. My quantum mechanics is not strong enough to talk authoritatively about that.

That's right. At high enough energy densities, you'd have a plasma of particles and anti-particles, mixed with the photons, in some kind of thermal equilibrium.

 

[CANGAS]

Let's regain our focus, gentlemen.

The compression of light, given a certain vagueness of the original question, most likely means can the wavelength of a pulse of electromagnetic radiation be made into a shorter wavelength.

It can be, and is very often observed to be so. A prime example is Doppler effect, used by astronomers and military surveilance and other numerous activities.

There are other ways that science recognizes that a light wavelength can be shortened. Perhaps the original questioner can clarify and expand the query.

 

[Billy T]

...If you had a perfectly reflective material then you could make a box or bottle out of it and you could "store" light in it. Of course, there is no such material, but we can pretend. In any case, if you reduced the size of the box without letting any light "leak out" then you would just get a higher energy density box of light. ...

Yes, but see Cangas also. The number of photons in Dale's box will not change, but as each is reflected off the inwardly moving wall(s) the Doppler effect will add energy to it. (No quantum mechanics required for this one, but if you are good in thermodynamics you will get the same results, with no "Doppler details" as the even spin (zero) photons are a "compressible fluid." I am not so sure that a "perfect lossless box" of odd spin particles can be equally well treated by thermo. Perhaps Physics Monkey reads and tells us.)

By edit: More I think about it the less certain I am that Thermo works even for photons, etc. My worry is that thermo will want a temperature to exist and I do not see how the Maxwell - Boltzman distribution is preserved via the Dopper shift equations alone, especially if I am mean and move the walls at two or more different speeds. Help PM (or anyone who can - this is getting serious! - I have stepped into "deep yoguart" again. Perhaps photons can scatter off each other, via some usually neglected high order effect, so all is well in "thermoland."?)

 

[Billy T]

To James R & DaleSpam:

Both of you are compressing much more than I was considering, but even so, why are you expecting anything but ever more energetic gama rays? Are you suggesting the "higher order effects" I aluded to in my edit below? If so what are they?

Also, James alone:
Why must it be "equlibrium"? (In this highly idealized case.)

More worries (and reasons why I hope PM is reading): I no longer am even sure we can neglect QM as when the distance across the box is less than the "photon length" (long if energy is well defined), we may need to be speaking "particle in box" terms etc. Lets start with galaxy size box. - They are on sale now at GD (galaxy depot) and compress only down to solar system size, to avoid this one, at least initially.

Please help soon PM, et. al. - The yoguart is entering my ears and I can only breath with my head tilted way back.

 

[ecclesiastes]

since a photon is a boson..any number of photons can be concentrated in a given quantum level...would this be compression? this occurs in the plasma region of stars yeah?

 

[Chatha]

I think so, light is energy, neither particle or wave. photons themselves are packets of energy, compressed energy.

Let's regain our focus, gentlemen.

The compression of light, given a certain vagueness of the original question, most likely means can the wavelength of a pulse of electromagnetic radiation be made into a shorter wavelength.

It can be, and is very often observed to be so. A prime example is Doppler effect, used by astronomers and military surveilance and other numerous activities.

There are other ways that science recognizes that a light wavelength can be shortened. Perhaps the original questioner can clarify and expand the query.

Them lasers are compressed variant of light, fire is in fact also a compressed form of light since it has a relatively shorter wavelength than fluorescent white light. Given that short wavelengths usually have a high energy, as in microwaves for example. So yes light can be compressed.