So there's some really interesting applications of accelerators, way outside of the realm of particle physics, that we're starting to get a handle on. - Suzie Sheehy

Now it's not obvious to most people how this acceleration mechanism of using a wave to accelerate particles actually works. So I have a little demonstration... of an everyday example where I can use a wave to accelerate some particles. This is just an ordinary fluorescent tube that you have in the ceiling... Over here I have a plasma ball which has a 30 kHz oscillating AC voltage supply. So there's a voltage, it's a couple of kilovolts that's going up and down, up and down, up and down in the center of that thing, 30,000 times a second. And because of that, out of the plasma ball... comes an electromagnetic wave that's traveling... through space. So move towards the plasma ball and point the fluorescent tube toward the plasma ball. [It lights up] ...So actually if you move it away, notice that it's still on. Now a lot of people show this demonstration with the fluorescent tube touching the plasma ball and say that it's something about completing a circuit... It's not. It's the electromagnetic wave that's coming out... which is traveling through the fluorescent tube, exciting the electrons inside. ...you know how a fluorescent tube works.

So when we're thinking about radiation and radioactivity, it is worth keeping in mind that just the fact that something is radioactive does not means it's harmful...

So what is ? It's energy in the form of moving particles or waves, emitted by an atom or another body as it changes from one energy state to another. That's the official definition.