Radiation: causing horrible things like cancer and warmth and food and cellphones and sunsets since the beginning of time. Sorry what are we, what are we talking about? [Intro] Welcome, to another edition of I Don't Think It Means What You Think It Means. Radiation. It's when energetic particles or waves move through space, and it's pretty much the best thing ever. Radiation includes:

• Visible light, which is always bouncing off of stuff and hitting our retinas, allowing us to not stub our toes and generally enjoy the splendor of the world. It's also what plants convert into the food we eat.
• Infrared, or IR radiation, which is the stuff that actually warms the earth, so it's the reason that we're not all freezing to death right now.
• Microwaves, which not only heat up our hot pockets, but also transmit our cellphone calls. A huge amount of study into whether these microwaves cause cancer indicates that they probably do not, and the World Health Organization classifies them in the "Needs more study" category along with coffee and pickled vegetables.
• Radio waves, which carry, yes, radio signals. Yes also 3G and Wi-Fi and all that good stuff.
• And then we have the extremely low and very low frequency waves, which aren't super useful, but don't hurt anybody either.

Unlike all the above examples, some kinds of radiation can transfer their energy into atoms and ionize them, removing electrons, which is where the problems begin. When most people think of radiation, what they're really thinking of is this radiation, which is Ionizing Radiation. Including:

• X-rays, that can ionize atoms, but it's generally worth it to take a peek at your broken bones.
• Ultraviolet Radiation, which is mostly non-ionizing, but can excite atoms enough to cause some unwanted reaction, like in our skin, which is why we put on UV protection in our sunblock.
• Gamma Rays, which are pretty much the worst kinds of all the radiation, because they can travel through pretty much any material, and then ionize an atom right out of your DNA, leading to some pretty serious problems.

Now thus far we've only been talking about waves, but as I said at the beginning, radiation is energetic waves OR particles, so there are some forms of radiation that are actually particles with mass. These kinds of radiation are only caused by nuclear reactions.

• An Alpha Particle is a flying bit of nucleus: two protons and two neutrons stuck together. They're so big and slow that they don't generally cause much damage, unless you ingest something that's emitting them, so I'd suggest you don't do that
• Beta Particles are energetic electrons that are more ionizing than alpha particles, less ionizing than Gamma rays, so they cause some serious damage as well.

So now you know. And if you're friends don't know, send this to them, because if we use the word 'radiation' like it's evil, all of the helpful forms of radiation might get angry and go on strike and then we would all die! Thank you for watching this episode of Sci Show: I Don't Think That Means What You Think It Means If you would like to suggest future topics for this program, please leave them in the comments, or you can connect with us on facebook or twitter. We'll see you later, goodbye. [transcribed by Ana Pond]