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Recap: Radiation is a mechanism for a large array of pseudosciences out there today, almost on par with quantum mechanics. The purpose of this episode is to provide a primer of radiation - what it is, what it isn't, why some is scary, and why some isn't. In going through this discussion, I also address numerous pseudosciences, including claims by proponents that the Apollo missions were hoaxed, that granite countertops are deadly, that microwave ovens are irradiating your food, and that cell phone and wifi signals are harming you in some way.

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Episode Summary

Topic: There is no specific claim that I'm addressing in this episode. Instead, I want to do a very basic science episode so that you, the listener, have a thorough background to understand the term "radiation." The idea of deadly radiation doing ... something— anything, really ... is pervasive in many different kinds of pseudoscience, including things I have talked about on the show like the Apollo moon landings to things I haven't talked about on the show and don't plan on addressing in their own episodes, like cell phones and whether your pretty granite countertops are slowly killing you. The term "radiation" has become one of the catch-all boogymen of conspiracies, and personally, I've found that the attempts to explain it in other podcasts by saying things like, "cell phone signals are non-ionizing," to be not incredibly useful. So, let's try to demystify this concept.

The Very Very Basics: Waves and Particles

The fundamental physics definition of radiation is simply the emission or the transmission of energy through anything, be it space or something we would perceive as solid. That energy can be in the form of waves or particles.

That's it, that's all radiation is.

So then it's the different energy levels of radiation that we have to explore, and that's where we get to ionizing vs nonionizing radiation.

Structure of an Atom: Ionizing vs Nonionizing Radiation

In chemistry, the basic building blocks of everything we do are atoms. All you need to define an atom is a single proton which is a relatively massive, positively charged piece of matter. Protons can be joined by neutrons in the core of an atom, and you can try to cram a bunch of neutrons together in an atom, but eventually it goes unstable and the neutrons will fly away, much like the last time I tried to pack too many clothes in a suitcase. Sometimes, a couple of protons will leave along with the neutrons.

Atoms can also have negatively charged particles bound to them, also known as electrons. These are relatively light particles compared with the proton or the neutron, weighing a little under 1/1800th as much. Just like you can cram in neutrons, you can add or subtract electrons to an atom. If you have just as many electrons as you have protons, then the atom is electrically neutral. If you add more electrons to an atom than there are protons, it will become electrically negative; the opposite is also true, such that if you have fewer electrons than there are protons, the atom is positively charged.

If an atom - or a group of atoms called a molecule - is NOT neutral, as in the number of electrons is not the same as the number of protons, then it is called an ion. So an ion is just a molecule that has a net electric charge, either positive or negative.

Therefore, following the terminology, ionizing radiation is radiation - that's either a particle or a wave - that has enough energy to change the number of electrons in an atom. It always does this by removing the electron, so that the atom becomes more positively charged. The reason this is bad is that chemistry in your body, like basic DNA replication, requires atoms and molecules to be charged the way they want them charged, and changing that will interfere with normal body processes.

More on that later.

"Types" of Radiation: Overview

With that all said as more of an overview into the terminology, I want to spend the bulk of this really talking more about what radiation "is." I already gave the basic physics definition, but that's not necessarily meaningful to most people. So what I'm going to do now is talk about a lot of examples of radiation.

"Types" of Radiation: Cosmic Rays

The first kind I want to talk about are cosmic radiation, or cosmic rays. "Rays" here is a bit of a misnomer because pretty much anything identified as a cosmic ray is actually a particle. A lot of these are from the sun and they form the solar wind. This is mostly composed of energetic protons. In particle physics, when we refer to a specific particle as "energetic," we mean that it's moving really fast: The energy of motion. Usually.

Cosmic rays also come from outside the solar system, originating from other stars or much more energetic events like supernovae, gamma-ray bursts, or black holes. Galactic cosmic rays - as in, ones that don't come from the sun, are even more energetic than solar cosmic rays.

On Earth, our atmosphere shields us from most cosmic rays. The particles will enter the atmosphere and usually hit an atom or molecule in our atmosphere, interacting with it, and releasing its energy in the form of other particles. Those secondary particles can still reach the ground, or interact with other molecules in the atmosphere. But, the safety of our atmosphere extends only so high, and if you are in an aircraft flying at a standard 12 km or about 40,000 ft, you are exposed to 10 times the cosmic rays you're exposed to on the ground, at sea level.

Earth's magnetic field will also help shield us from cosmic rays, but only ones that are positively or negatively charged. Electrically neutral cosmic rays won't, effectively, "see" Earth's magnetosphere.

And, cosmic rays can do significant damage to humans and to electronics. They are one of the major engineering problems to sustained human exploration of space because of their high energy and therefore their ability to interact with molecules in the human body and do bad things. They also will interact with electronic systems and they have not only led to faults in spacecraft computer systems, but also just fried the electronics beyond recovery.

That's not to say that you can't survive in space. It's all about the dosage, and it's all about playing the statistics. Just like there's no hard limit of the number of airplane flights you can take and then you die -- like, you can take 38 flights in a year and you'll be fine but don't you dare take that 39th flight or you'll die -- the same thing goes for spaceflight. It's the cumulative dosage that causes problems, in people. If one cosmic ray interacts with one cell over your lifetime, your body will be able to recover. Or 100 in a year. But maybe once you start getting past interacting over a million times in a one-week period, then we have issues. And for the record, I'm making up the numbers here. I don't want to actually get into radiation monitoring and dosage levels specifically in this episode, the point is just to understand the concepts.

And with that said for people, the same goes for electronics. Let's say you have a spherical spacecraft that is 1 meter in radius. And, one cosmic ray that can do damage will pass through the cross-section of that sphere every second. But, the electronics that could be damaged are only a small part of the spacecraft. So, you just play the numbers. If the electronics that could be damaged are only 1% of the volume, then in any given batch of 100 seconds, you are likely to have one cosmic ray hit the electronics and do damage. But let's say you have some way to shield them from most cosmic rays. So now, the ones that can both get past your shield and do damage will only hit once a year. Now, if you have thousands of these spacecraft out there, you would expect that half of them would have died after 100 years by playing the numbers. One you care about may die instantly, it just got "unlucky." Another one you care about may last 1000 years, it got "lucky."

So, that's the basic idea behind cosmic radiation as well as shielding humans and electronics from that radiation, or at least what shielding does or tries to do. In practice, because cosmic rays are so energetic - meaning they're moving really fast and so when they slam into you they can release a lot of energy - they are among the most dangerous forms of radiation in the universe. They are ionizing because they have enough energy to remove electrons from molecules within living cells in your body.

"Types" of Radiation: Ionizing Particle Radiation

The next kind of radiation I want to discuss are also ionizing radiation - remember: that's the radiation that can remove electrons from an atom. But now, I want to talk about the particle form of ionizing radiation in a more general sense. Namely, alpha, beta, and neutron radiation.

Alpha radiation is formed through the alpha decay process of heavy atoms. This gets back to what I talked about early in this episode, that if you cram a bunch of neutrons into an atomic nucleus, it can become unstable and will spit out stuff. Depending on exactly what's going on, one of the things it can spit out is called alpha radiation.

Alpha radiation is something that you'd never really think of as being "radiation" -- it's helium. Specifically, helium-4. Helium is defined as any atom with two protons. Helium-4 means that the total protons and neutrons in the nucleus of the atom add up to 4, so it has two protons and two neutrons.

Usually, helium is perfectly safe. People breathe it in at parties to sound like a chipmunk. What can make helium - or alpha particles - or even more scary-sounding alpha radiation - dangerous is when it's energetic, meaning from before, that it's moving really fast.

Helium itself, when stationary, is the heaviest form of radiation. Therefore, it doesn't have to move as fast as other types of particle radiation in order to do the same kind of damage, IF it can get to something that it can damage. What I mean by that is that not only is helium heavy, it's big. A bowling ball traveling slowly is going to hurt just as much if it hits your foot as if you throw a light tennis ball at your foot. But, if you have a gate that is small enough to let tennis balls through but not bowling balls, then it doesn't matter how fast that bowling ball moves, it's not going to hit your foot. Unless it breaks the gate.

So, typically, alpha particles are harmless unless they somehow get into your body, or something that emits alpha particles gets into your body. So helium won't get through the dead layers of your skin. Effectively, it's nonionizing radiation outside your body. But if you ingest something, like eat it or breath it, and that something then emits helium atoms in your body, that can do damage.

So, let's say you have a granite countertop. That granite is a rock, and just like any rock that's a combination of lots of different minerals, it has some heavy elements in it, and some of those are radioactive. Such as radium, uranium, and thorium. What that means is that these atoms are unstable over the long run because they have too much crammed into the nucleus of the atom. And, over time, they will decay, emitting other particles.

Let's take uranium. Uranium-238 is actually quite stable, with a half-life of the age of the solar system. But that doesn't mean every atom of uranium-238 will live 4.5 billion years and then all at once decay. It means that after 4.5 billion years, half of it has decayed, which is why the 4.5 billion years is called a half-life. So, uranium-238 will decay into thorium-234, emitting an alpha particle. Thorium-234 has a half-life of only 24 days, at which point it decays into protactinium-234 by emitting a beta particle, which I'll discuss in a minute or two. This only has a half-life of a minute, then it decays again, then that only has a half-life of 7 hours, and it decays again. There is a whole complicated series of different decay products, but they all decay by alpha or beta radiation and eventually end up as the very stable atom, lead-206. In this process, it will emit 8 helium atoms.

And, one of the intermediate products is a gas: Radon-222. Radon-222, as a gas, can escape from a nice pretty granite countertop and be inhaled. It only has a half-life of 35 ms, but remember we're talking about a single atom here. If you're working at your countertop all day, chances are you WILL inhale some radon gas. And, its byproducts will release 4 alpha particles before they turn into lead. According to an old episode of The Reality Check I was listening to on a drive through northern Arizona, and double-checked on WebMD, radon gas is the third leading cause of lung cancer with an estimated 12% of all lung cancer deaths attributed to radon gas in the US, or 15,000-22,000 per year. All because of helium atoms.

With that said, when I redo my kitchen, I'm getting rid of the tile countertops and putting in granite. And putting a lot of sealant on it. I'm much more likely to die of a car crash, or since I'm in the US, of a stray bullet, than I am to die of radon gas poisoning.

Moving on, the second kind of particle radiation I want to talk about is beta radiation. Beta radiation is either an electron or, if positively charged, the antimatter form of an electron, the positron. The electron form of beta radiation occurs when a neutron decays into a proton, releasing a beta-minus particle (electron) and an antineutrino. Together, alpha and beta radiation are exclusively the methods by which heavier atoms will decay into lighter atoms.

Because it's the size of an electron, beta radiation is much smaller than an alpha particle, and so it can get through the outer layers of your skin. But, a few centimeters or about an inch of plastic, or a few millimeters of most metals will stop beta radiation. But, if the beta radiation is highly energetic -- again, moving really fast -- or if it somehow gets inside your body, it can do damage by stripping electrons from atoms.

The third kind of particle radiation is neutron radiation. As an electrically neutral particle, it's hard to make neutrons an ionizing form of radiation, but it can do so indirectly. Let's say you have a really fast moving neutron. The neutron itself can't do anything to ionize an atom. But, if it slams into something, like a hydrogen atom which can just be a proton, it will transfer some of its energy of motion. Just like hitting billiard balls. Then, that now-fast-moving hydrogen atom is charged, is energetic, and it can do damage by stripping other atoms of their electrons.

BUT, unlike alpha and beta particles which are reasonably stable (except for positrons, which annihilate with an electron and release a gamma ray which I'll talk about in a moment), neutrons are surprisingly UNstable. Much like my chickens, when they're caged in with other particles like protons, they are quite stable and will have a long and healthy lifetime. But, if let out, a free neutron just like a free chicken up here in the mountains won't last very long. The half-life is just under 15 minutes. That means that for neutrons to really do much damage to a person, you have to be in a place that has a lot of neutrons, that gets them up to high speeds, and you're likely to get them into your body. Typically, a nuclear reactor will satisfy these, and not much else.

So, at the end of this section of the episode, about ionizing particle radiation, you are typically pretty safe in most of your daily life. You likely don't work inside a nuclear reactor, and you probably have a little bit of radon-gas-emitting rock in or in the bedrock underneath your domicile, but there's lots of other stuff that'll probably kill you first.

"Types" of Radiation: Ionizing Light Radiation

Next up in this discussion is the final type of ionizing radiation: light. It's also nonionizing, but I'll talk about that next. What makes light ionizing or not is its energy level. Because light can act both as a particle and as a wave, I'm just going to refer to it as a photon.

In order, from the most energy to the least energy, photons are classified by physicists as gamma rays, x-rays, ultraviolet, visible, infrared, microwaves, and radio. On the ends, gamma rays have no high-energy cutoff point, and radio waves have no low-energy cutoff point. While there are formal cutoffs between each type, this is to a certain extent an artifact of the human desire to classify things. In nature, it's not like a photon is a gamma ray and it loses a quantum of energy and then suddenly its entire nature changes and it becomes an x-ray. These are really just fairly arbitrary delineations in physics, though they are useful in a couple of ways.

For example, perhaps obviously, visible light is light that the human eye can see. But, even that is not as exact as you may think, because each eye is different and the high and low cutoffs are different for each person. For example, there's an absorption line in the sun's spectrum that is in the infrared, but it was defined before we knew how to predict them and before we had technology to see infrared light, meaning that the person who discovered that line was able to see a little bit into the infrared that most other people can't.

The delineations are also useful when classifying ionizing versus nonionizing types of light. All gamma rays have enough energy to be ionizing radiation. All x-rays have enough energy to be ionizing radiation. MOST ultraviolet has enough energy to be ionizing radiation. Visible light, infrared, microwave, and radio do not have enough energy to be ionizing radiation.

If a gamma ray is headed towards you, it is so high energy that it easily gets through your skin and can impact denser muscle or bone tissue, knocking off electrons as it gets absorbed or absorbed and re-emitted at lower energies and absorbed again. As with anything, though, if you have enough material between the gamma ray and you, that material will absorb the gamma ray and you'll be safe.

Same goes for an x-ray. X-rays have enough energy to get through most tissue in the body except for bone, and that's why x-rays are used to image bones. What happens is that you are placed between the x-ray generator and the film. The x-rays pass through the soft, lower density tissue of your body and are absorbed by the film, but the x-rays do not pass through the denser bone and so do not hit the film.

By the very fact that x-ray imaging works, your body is absorbing that x-ray radiation and causing damage to your cells. But, as with everything discussed so far in this episode, it's all about the dosage.

All of these forms of light are also emitted by the sun and all other stars. While it's true that the majority of the sun's light is emitted in visible and near-visible energy levels, some is emitted as gamma rays, and some as radio waves. Some as x-rays, some as microwaves. Some as ultraviolet, and a lot as infrared. If you are on the dayside of our planet and can see the sky, you are being constantly hit by gamma, x, and ultraviolet photons from the sun. So to my colleague who just got the window office with several windows and a beautiful view of the mountains, you're getting more radiation than I am in my office where my window faces an office building and I can't really see the sky. So there!

But more seriously, we are all getting exposed to this kind of radiation constantly, and we don't all develop cancer at age zero and die. So it's all about the dosage. From RadiologyInfo.org, a quick bone x-ray of an extremity, like your hand or foot, is equivalent to being outside for 3 hours. "Big whoop" as the kids may or may not be saying these days. A chest x-ray is longer, where you get two years' worth of x-rays during the imaging. A dental x-ray is between the two, at one day's worth of x-rays. That's why it's not dangerous for you to get a few x-rays at the dentist once a year, but the dental hygienist who may perform several on patients per day should be behind a protective screen. It's all about the dosage.

In comparison, the Apollo astronauts did wear radiation detectors. The maximum dose was absorbed by the Apollo 14 astronauts at 28.5 mSv, which is equivalent to about 9-10 years of normal background radiation on Earth's surface. So in the space of a few days, they got nearly a decade's worth of radiation. Not good. But not deadly. You get almost the same amount from getting a PET scan. But if this had been a mission to Mars, where they were traveling in space for 6 months as opposed to 10 days, we're talking about literally more than an order of magnitude difference, and we're getting to the point where that is a lethal amount of radiation. That's why we were able to go to the moon with Apollo and radiation wasn't a problem, but radiation is a significant issue when designing a human mission to Mars.

With that said, I got side-tracked a bit. I talked about gamma rays and x-rays, what's left for ionizing is ultraviolet. Ultraviolet, or UV, not to be confused with the insanely obnoxious digital rights management system called UV that just came with my Star Trek 4K blu-ray, comes in yet again three sub-types which have varying levels of danger for people. And, unhelpfully, not only are there three sub-types of UV light, but there are two different ways to make three sub-types, the second way adds another three to make six sub-types, and they're all used more or less commonly.

Going from most dangerous to least dangerous, so from highest energy or shortest wavelength to longest wavelength or lowest energy, there's extreme UV, or EUV. EUV is just as ionizing as x-ray but it's completely absorbed by Earth's atmosphere so almost every human doesn't have to worry about it. Next is vacuum UV or VUV which is ALMOST completely absorbed by Earth's atmosphere, so we again don't really have to worry about it. Next is a very very narrow range of UV that's emitted by the hydrogen atom. This is ionizing radiation, but yet again, almost all of it is absorbed by the atmosphere. There aren't really any natural sources of UV radiation on Earth itself, though humans have created plenty of artificial lights that generate UV at this hydrogen emission line. But, just as the upper atmosphere absorbs the majority of these three kinds of UV, the lower atmosphere absorbs them, too, so unless you decide to go tanning under an EUV light, you'll be fine.

Next up is UVC, roughly equivalent to far-UV through middle-UV. This is also absorbed by the atmosphere, but it is dangerous if you were to sit under a UVC light. UVB is next. This is mostly absorbed by the ozone layer, but not entirely, and some UVB light from the sun will hit the ground. This is especially true if you live in an area of Earth where the ozone is particularly thin, including some equatorial areas, the south pole, and also Australia, but it changes seasonally and is really only a big issue during their autumnal months. And Chile in South America has really thin ozone.

Finally, there's UVA, roughly the equivalent of near-UV. This is not absorbed by ozone, and almost all of the UVA from the sun makes it to Earth's surface. It's also UVA that most artificial sources of UV light will create, including UV LEDs, most UV lasers, and "black lights."

In humans, fortunately, UVA does not do much damage at all. UVA photons are generally nonionizing and won't damage your DNA. UVB, however, does. And, as I said when I first introduced this section on light as radiation, nature doesn't really care how humans have sub-divided things. That means that some of the higher energy UVA photons will cause harm. But once you get into the middle of the UVB and definitely into UVC, you start to have issues.

It's because of this continuum, and it's because of how this continuum interplays with atmospheric absorption, that medical professionals say you shouldn't spend too much time in tanning beds or out in the sun. If you do spend a lot of time outside, you should protect your skin in some way. The UVB photons can penetrate the dead layers of skin and get to the living cells underneath and cause damage. Sunscreen lotion has specific molecules in it that are designed to absorb or reflect these wavelengths of light and prevent them from making it to and through your skin.

There are plenty of other podcasts or places you can get more information on that so I'm not going to go into more detail on how these work, but the fundamental concept still comes down to the idea of blocking the radiation -- in this case, higher energy photons of UV light -- from making it to and through your skin to then interact with the molecules in your body, stripping electrons and doing bad things as a result, like interfering with proper DNA replication. And again, it all comes down to dosage. If you have melanin in your skin, which is the molecule that darkens skin, spending an hour outside probably won't do much damage. If you have albinism and so lack any melanin, it will. If you have a lot of melanin in your skin and so have a darker skin tone, you could probably spend all day outside at latitudes where there's a lot of ozone, such as most of the United States or Europe, and not have any issues. If you have less, or you're lilly-white and semi-translucent like me, then you may have some issues if you try to do that.

"Types" of Radiation: Nonionizing Light Radiation

The almost-last type of radiation I'm just going to briefly touch on is nonionizing light radiation. I've talked about particles which are bad and light which is bad, but there's other light that isn't bad. Once you reach visible, you're good. Visible, infrared, microwave, and radio do not have enough energy to ionize matter in your body and cause any damage.

It really doesn't matter how much radio wave energy is beamed towards you, it's not going to do damage to you because it doesn't interact with the matter in your body.

This is what Einstein won a Nobel Prize for, the Photoelectric Effect. It doesn't matter how intense the beam of energy is, so for example, how strong the microwave signal is: It's not going to dislodge electrons from the material. It will only dislodge electrons if the energy level of the individual photon is enough to do so, so you have to go up the energy spectrum and hit it with something like ultraviolet, x-ray, or gamma-ray photons. (And to those who are pedantic, this is not a 100% accurate and generalized description of the Photoelectric Effect, I know that, but I tailored it to fit into the situation I'm talking about.)

With that in mind, the same goes for cellular phones and wireless internet. I don't care what people who claim they have EHS (electromagnetic hypersensitivity) claim: Infrared, microwave, and radio energy does not interact with your body, the individual photons – regardless of how many photons there are – do not have enough energy to hurt you. With a tiny asterisk.

That asterisk has two caveats. The first caveat is how a microwave oven works. The oven works by emitting a SINGLE frequency of light in the microwave range. That single frequency coincides with the frequency that is absorbed by water. And so, the way the microwave oven works is by emitting that light and it's absorbed by the water molecules in the food or drink inside the oven. As those water molecules heat up, by simple conduction -- which is touching -- the surrounding molecules will heat up, too. Like if you're in a tightly packed room and someone starts to move, everyone around them has to move, too. That's it. The microwave photons can't escape the microwave oven because it has shielding that is extraordinarily efficient at reflecting those photons back inside the oven so they are absorbed by the food.

And through this we can examine one of the common pseudoscientific claims, that microwave ovens irradiate food and render it either radioactive or devoid of any nutritional value. First off, we have to define "irradiate." All irradiate means is to expose to radiation. Meaning that we expose it to energy in the form of particles or waves. In the case of a microwave oven, it's waves. Therefore, the implication that the food is somehow absorbing deadly particles is completely wrong even though technically it is being irradiated. But those microwaves are absorbed by the food, and nothing is left but heat. As to the claim that it destroys the nutrition in food, that's correct ONLY in the sense that when you cook food, you are destroying some of the chemical bonds in the molecules which are beneficial. Cooking over a stove, a grill, a fire pit, or a microwave, in broad brushstrokes, is not going to be very different in terms of destroying micronutrients. In fact, very generally speaking, most micronutrients are lost due to leaching into water when cooking, so the faster cook times in microwave ovens tends to decrease the overall nutrient loss than if you were to cook over a stove.

But getting back to this basic idea, there is no basis for the idea that microwave ovens do bad things to food.

The second caveat in my statement that EHS is bogus is infrared light. Infrared light can be felt as "heat" energy. When these photons are absorbed by the outer layers of your skin, they increase the energy level of the dead layers of your skin, heating them up. In that sense, infrared light can interact with the human body, but it doesn't do damage unless you're in an infrared oven and so get cooked.

"Types" of Radiation: Thermal Radiation

Which formally brings up the final kind of radiation, and that's "thermal" radiation, so-called because we feel it as heat. Any kind of light that your skin can absorb, if exposed to enough of it, you will feel as heat. This is pretty much ultraviolet, visible, and infrared in most peoples' general experience. This is the concept behind "heat lamps" in a cafeteria, or if you have a high-wattage laser pointer, you can light a match or burn yourself. In these cases, the skin is literally absorbing the light energy, and by absorbing it, that energy is being converted into heat. If your skin can't re-radiate it to the environment, or distribute it throughout your body faster than it is absorbing it from the light source, then its temperature will increase.

This can also happen with microwave ovens, but it can never happen under natural circumstances. If you were somehow able to break your microwave oven such that the microwaves could escape, then you can burn your skin and muscles because the microwaves are at a frequency that will penetrate into the body to about 17 mm, or a bit over half an inch, where muscle lies. In the few case studies where this has happened, different people have had different amounts of damage, though it's almost all been temporary. And, most other microwave photons will go less deep.

For example, the Active Denial System, nicknamed the "pain ray," uses microwave energy at a frequency that penetrates only 1/64th of an inch, or 0.4mm, into the human body, which is still skin, and in two seconds can heat the tissue to 130°F or 54°C, which they claim will cause pain with no lasting damage. But again, it must be said that this is a dosage issue: The pain ray works by focusing the beam of microwaves and using a very high wattage. Significantly higher than any microwave oven: The wattage the US military was using about a decade ago was around 100 kW, while the average microwave oven is closer to 500 W, or 0.5% as much.

With microwaves, the higher the frequency, which means shorter wavelength and closer to infrared light, the LESS deep it will penetrate into the skin before being absorbed. That means that once you get to radio waves, most will pass through the body without being absorbed at all. Effectively, the radio photon doesn't even "see" the human body.

Summary

With that said, we've reached the summary part of the episode where I'm going to try to put all these different parts together and hopefully you will be able to better understand the dangers and non-dangers of the term, "radiation," and then I'm going to talk about another example or two of pseudoscientific claims.

First, to recap the most basic thing, radiation is simply the emission or transmission of energy. This is done through particles or through light.

There are two ways that radiation can hurt you.

First is what's called ionizing radiation, which means that when the particle or light hits you, it has enough energy to remove electrons from atoms. That means that all the careful chemistry that goes on in the body is now messed up for wherever that atom is. This happens all the time, the issue is just how much happens at once, or cumulatively over time. In particular, this can mess up DNA replication which can lead to bad things like different types of cancer.

For radiation to be ionizing, it has to first have enough energy to knock an electron off, and second it has to be able to get to live tissue in your body. That "enough energy" comes in the form of moving very quickly for particle radiation, or being really short wavelenghts for light energy.

But, it still has to get into your body. Alpha particles are just helium atoms, and so unless you ingest the substance that's going to emit alpha particles, it's not going to hurt you. Beta particles are a bit more able to get into your body, but if you're wearing a tinfoil suit, you're fine. Neutrons are also bad, but unless you work in a nuclear reactor, normal people don't have to worry about that. Cosmic rays are similar, but typically much higher energy than any of these and are a real issue for prolonged spaceflight if you're not protected from them. Short flights are fine -- again, it's all about the dosage.

Which brings us to gamma rays, x-rays, and ultraviolet (which I initially wrote in my notes as "ultraviolate"). In order, those will go through your body more to less easily, but fortunately ultraviolet is blocked by our atmosphere for the most part.

The other way radiation can do damage is through thermal heating. If the radiation is nonionizing, it can still be absorbed by anything, and that absorption of the energy is just going to cause the substance doing the absorbing to heat up. Put your hand under a heat lamp, and your hand will heat up. Those infrared light rays are absorbed by the very upper-most layers of your skin. You're not being irradiated in the sense that the radiation cannot alter the chemical structure of your body in and of itself. The only way this becomes an issue is if you absorb too much of the energy, you can be burned, just like touching a hot stove.

That means that wireless internet and phone signals, which operate at microwave wavelengths, also do not irradiate you in the sense of doing damage to your cells which could cause cancer. Yes, if you strapped a giant power source to your cell phone and boosted the strength perhaps 100-fold, you might start to feel some heat from the microwave emissions, but all that's going to do is heat the upper few millimeters of your skin. The fact that if you place a glass of water in the microwave oven for a minute and it gets hot, but you could place a glass of water next to a cell phone or a wifi router all day and nothing changes temperature-wise SHOULD be evidence enough that these claims by fear-mongers and hypochondriacs are baseless.

And, again, when we say it's "nonionizing," that means that there is not enough energy in the individual light particles to change the structure of the atoms, to move electrons. All it does is heat things up. These might sound like they are the same, but they are very different.

And so, there you have it, a primer on radiation. Hopefully this helped you to understand the dangers and not-dangers of radiation in a clearer way that you may have heard on other podcasts and will help you to understand and combat pseudoscience in a wide variety of instances. For example, the next time a parent complains that wifi in a school is harming children, you can use what you learned in this episode to understand why that's wrong, and even point to the experiment of placing a glass of water near the wifi router for hours to show that nothing happens.