Pure Energy?, What is it?

I was reading about antimatter the other day, and it mentioned that when antimatter collides with 'regular' matter, they produce pure energy... I was wondering, what exactly is PURE energy.
I asked a friend, but keep in mind that I am only a sophomore in high school, and my friends don't really know anything more than myself... They said that pure energy simply does not exist.

Thanks for your help.

when a particles and it's antiparticle annihilate they produce what classically we would call light. Since it's pretty high energy light we would probably call it X rays or gamma rays.

However, annihilation of a particle and antiparticle is not really a classical event - it's described by quantum field theory. in QFT, light appears as particles called photons. Photons are massless and travel only at the speed of light c.

Hope this helps.

Here's another way to look at it:

In quantum mechanics, every particle has certain "quantum numbers" associated with it, which describe its identity. For instance, the electron has a "lepton number" of +1, a charge of -1, and a spin of 1/2. When particles interact, all of these numbers are CONSERVED, like energy is conserved. This is very similar to balancing a chemical reaction: the numbers on both sides of the reaction must match to ensure that everything balances out.

There are other numbers, such as baryon number, strangeness, charm, (yes, physicists choose some odd names for things), which are USUALLY conserved, unless the so-called weak force gets involved. Anyway, the point is that when a particle and its antiparticle annihilate each other, all of their quantum numbers are precisely opposite, so the net number is zero. The photons that are created have all zeroes as their quantum numbers, except for spin. They have a spin of 1.

So the idea is that when other particles annihilate into photons, you can ask about the photons, is it a lepton? (no), is it a baryon? (no) is it charged? (no) is it strange? (no), is it charmed? (no), is it spinning? (yes). Therefore the photon seems to be nothing but "spinning energy" without any other identity. I think this is what people mean when they say that it is "pure" energy. Of course, there is a lot more to the story, but I think this is a fair representation of the point of view that labels photons as pure energy.

Hope that helps!

--Stuart Anderson

Stuart, thank you, as usual for bringing light to the discussion.

A photon is a wiggle between electric field and magnetic field, classically, I think. What handedness are photons? Does that have something to do with polarization?

Could one detect an 'anti-photon' as being any different from a 'pro-photon'? My assumption is no, but why?

Sorry for asking for an entire course précis on Saturday...

its also a form of theta radiation

OK.

Star Trek answers aren't real, for God's sake, spacepuppy.

Energy is simply motion.