I’m used to thinking of photons as visible light. But since visible light is simply a part of the EM spectrum, are terms we use for visible light equally applicable to non-visible wavelengths? Can we refer to a photon of radio energy or a photon of ultraviolet light?
Absolutely.
Yes. I’m not sure how much more discussion you’re looking for on this.
That pretty much answers it for me. Thanks.
Yes, yes, and yes.
Stranger
Only if it’s preceded by “Zarking.”
How about this: are photons energy or do they merely convey energy? If they are energy, then what about other bosons, especially W and Z bosons?
Thanks,
Rob
You usually hear photon used more with the higher-energy parts of the EM spectrum, and radio waves tend to be talked about more in terms of, well, waves.
Is there a reason for this (soft) distinction? Is it because the wave nature of RF is more apparent on macro scales due to the macro-scale wavelength?
In theory, of course radio waves are quantized into photons. But it seems pretty difficult to set up an experiment where the particle-like properties of radio waves can be demonstrated. Anyone got an example?
A single quasiparticle photon detector for mm photons using a niobium antenna and an aluminum absorber. Got the graphic right here but can’t find cite.
Because the wavelength in the radio spectrum is so large, it would be very difficult (though not impossible, I think) to perform double slit experiment with radio frequency photons. And photons in this band tend to have such low energies that the photoelectric effect on any real material is minimal compared to normal thermal effects. In short, radio frequency photons are so “smeared” that it really is much more applicable to talk about them in terms of fields rather than discrete particles.
sweeteviljesus, gauge (fundamental) bosons are particles that all act as force carriers and have the unique property of being able to occupy the same quantum state as other bosons; that is to say, two gauge bosons can occupy the same position at the same time with the same spin. Asking whether they are energy or convey energy begs the question of what this “energy” thing actually is. As a force carrier, they can be spontaneously created and then destroyed as part of the act of moderating interactions between one system and another. They may be real, as in a photon that is emitted and directly observed, or virtual, for instance, mediating “intermediate states” in interactions between electric and magnetic fields. “Virtual photons” might seem like, to dispense with pleasant language, complete and utter bullshit, but in fact the concept is imperative to quantum field theory. Of course, QFT also requires that these virtual photons have properties that real observable photons cannot, and also involves a lot of dividing infinities and renormalizing away all of the inconvenient speciousness, so it’s stupid, but it works so it’s not stupid.
Are gauge bosons energy? As much and as little as any other particle. Fundamentally, they control how one system interacts with another; that’s about as much as can be said.
Stranger
Page 17 of this:
http://www.mpe.mpg.de/ir/irretreat2005/poglitsch.pdf
Technically, the term is applicable.
But in practice, it would just be confusing. Like aerodave said, the common terminology uses waves vs. photons for different parts of the spectrum. If your goal is to communicate with others in the field, that communication will be easier if you use the commonly accepted terms.
Not only could they, they DO talk about photons of UV light all the time. It’s very common and accepted terminology. And the UV reghion is precisely where you see quantum effects, like the photoelectric effect, that are direct evidence for photons.
An optics geek like me might talk about photons in the radio region, since it’s a packet of EM energy, and we’re used to thinking in those terms. You can explain radiation pressure in terms of EM fields or in terms of photons striking your target, but the latter has a visceral appeal.
There is one quantum effect I can think of at radio frequencies – emission from Rydberg atoms:
From an X-ray and radio astronomer’s point of view, on a practical (well, as practical as astronomy gets) note, its just easier to refer to radio parts of the spectrum as waves. The reason for this (in astronomy anyway) is twofold:
-
A photon of radio emission has a very low energy – at 1.4GHz, a single radio photon carries about 9x10[sup]-43[/sup] J of energy, compared to say an X-ray photon carrying 2x10[sup]-16[/sup] J. But there are also significantly more radio photons (at least in the astronomy I do) than X-ray photons – it just becomes more practical to treat the radio photons as waves and refer to the flux of the radio source (basically energy per unit area). Unlike in X-ray astronomy, where the energy is high enough (and the photons sparse enough).
-
A lot of radio astronomy uses interferometric techniques which are best understood from a wave description of EM radiation, so we end up referring to radio waves, my old thesis advisor did try, once (he’s an old school X-ray astronomer), to try and explain interferometry in terms of photons, before giving up and deciding waves were easier.