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Virtual Photons


  03:32:04 am, by Nimble   , 599 words  
Categories: Thoughts, Science

Virtual Photons

Have you ever wondered where forces in nature come from?

In mainstream physics, the theory goes that forces happen because matter exchanges little particles between them. Now, these are no ordinary particles, these are virtual particles. They 'borrow' energy from space, exist for a while, and then give it back.

Now, the lower the mass of these virtual particles, the longer they can exist. The strong force is supposed to be responsible for keeping nuclei together - otherwise, the balls of positive charge would blow themselves apart from a like repels like rule. It has a very limited range, so the virtual particle they imagine is somewhat massive.

Electromagnetism, on the other hand, is supposed to be of potentially infinite (though dropping off rapidly with distance) range. The virtual particle that fits the bill is a virtual photon.

Wait, though. Photons do not have very much to distinguish amongst them, except for their wavelength, and the wavelength is already used up in this theory to determine how far the virtual photon can go - the longer it is, the lower the energy, the further it can go.

So how, pray tell, do virtual photons count for both attractive and repulsive forces. Repulsive forces, you can imagine being just like little bullets. Attractive ones, though? Like between an electron and a positron? Or an electron and a proton?

I've seen a number of explanations. Very few of them are convincing, and the closest ones to convincing do not attempt a physical explanation, but a mathematical one. Let's survey the field...

There's the it wraps around the other side and hits the particles closer together because of the uncertainty principle explanation.

There's the the photon wave is spiky and somehow depends on the charge of the particle which spewed it explanation.

There's the a minus sign appears in the matrix explanation.

There are a number of other, not so helpful explanations such as "it's like a boomerang" or the "virtual photons transmit negative energy". Do a few Google searches... there are a lot of different explanations.

Personally, I think that the Uncertainty Principle, which in my mind is just a way of saying that measuring a wave two different ways (as Nick Herbert would point out, like trying to represent a sound as digitized values and sines waves at the same time) can only be done so accurately, does not imply a seething sea of not-real particles that hide underneath the measurement limit.

I've heard an explanation of where some of it comes from. Quantum electrodynamics comes up with "infinity" as the answer to many important questions, like the charge of an electron. Plugging in the "real" values makes everything work again, but how to explain it? If perhaps the infinite charge were "shielded" by virtual positrons (anti-electrons), then the infinity could go away. There are other ways virtual particles and the like can be used to renormalize quantum electrodynamics.

I'm sure there are more explanations than that. I'll have to brush up on a little more history.

Personally, I think the real explanation is going to be tied up in whatever may come of a future revolution in quantum mechanics. Repulsion and attraction change the shape of the probability waves (the equations that say "there's an x% chance that at this time, we'll find the particle at this spot"), and probability waves have a certain disturbing 'reality' to them (making it look like individual particles can "interfere with themselves" to create an interference pattern)

There, now you have 200% of your Recommended Daily Allowance of nerdiness. Megadoses may be harmful, so be careful :)

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