Category Archives: Universe

Don’t mess with gamma rays. Gamma ray photons, with their super short wavelength, are more energetic than a million visible photons combined. Energetic enough to damage cells, they can wreak havoc on a human body. Luckily for us, our atmosphere’s ozone layer filters out gamma rays. Certain black holes can emit “gamma ray bursts”, two ridiculously powerful, tightly-focused jets of gamma rays that unleash more energy in a second than our Sun will produce in its entire lifetime. If one of these happened anywhere within a few thousand light years of us, we would be toast.

Even though they interact very rarely with matter, neutrinos are absolutely everywhere — after photons, they’re the second most abundant particle we know of in the Universe, with trillions passing through your body every second. They don’t really have a size, because they are quantum mechanical particles, which means they follow their own weird rules. As “leptons”, neutrinos are cousins of the electron, but they carry no electric charge.

When you get on x-ray at the doctor’s office, here’s what’s happening: A machine shoots x—ray radiation through your whole body, and a detector on the other side of you absorbs the radiation that makes it through. X-rays have just the right wavelength such that they easily pass through the soft parts of your body (like your organs) while they are absorbed by the harder parts of your body, like bones. So the detector can see your skeleton by looking at what’s missing from the resulting x-ray image.

Developed in the 1930a, the electron microscope can “see” objects too small to be “seen” using light waves. Instead of relying on photons to bounce off the specimen the way on optical microscope does, the electron microscope fires a stream of electrons at the specimen through coil electromagnets.

Our eyes can see things as small as 100 μm. Optical microscopes let us go 1,000 times smaller. Electron microscopes can go 1,000 times smaller still, letting us see individual atoms. For now, that’s our limit — but microscopes of the future should be able to do even better!

About 99.999% of the mass and solid matter in an atom is in its nucleus, which only takes up one quadrillionth of the atom’s space. How small is that? Imagine scaling an atom up to the size of a basketball arena. The nucleus is a grain of sand floating in the middle of the arena — and the mass of the whole atom is the same as the mass of the grain of sand. (The diameter is calculated from the van der Waals radius.)

Helium is the creation of most solar fusion. When hydrogen atoms are squished tightly enough together, they combine into helium atoms in the process of nuclear fusion, which releases the energy that powers you and everything else on Earth!

When you have water in a bottle and there’s a bubble of air in it, the bubble always goes to the highest part of the bottle — because air is less dense than water. That’s the same reason helium balloons float. Helium is less dense than air, so it’s like an air bubble in the water bottle of the atmosphere. (The diameter is calculated from the van der Waals radius.)

Water is a big deal. Often called “the solvent of life” because of its remarkable ability to dissolve other substances. Water is also a rare substance whose solid, liquid, and gas forms all exist at human-friendly temperatures. Adult human bodies are 60% water and babies are 78% water. Babies are basically water balloons.

When water is ice, its molecules are arranged in a solid configuration. As heat increases past 0°C, water molecules come loose from the rigid configuration and start rolling around each other. As heat increases even more, the molecules start jiggling so vigorously that some fly off from the rest and into the air as water vapor. Once water passes 100°C, the jiggling becomes too much to keep any of the molecules together and they boil away.

Carbon atoms, arranged one way, form a soft graphite. Arranged another way, they form super hard diamonds. Arranged another way (along with a few other things), they form you — because carbon is a primary component of all living things. Carbon is so versatile because of its four covalent bonds, which allow it to bond with hydrogen, oxygen, nitrogen, and other elements.

You shed carbon from your body when you exhale carbon dioxide (C02), and plants do the opposite. Plants breathe in C02, which is then broken up into carbon to make more plants and oxygen as a waste product. Combustion is the process of oxygen in the air reuniting with the carbon in the tree to form CO2. Climate change is the result of ancient buried plants being dug up and burned for energy, which releases a whole lot of long—buried carbon back into the atmosphere as C02. (The diameter is calculated from the van der Waals radius.)

Imagine taking a two—dimensional sheet of carbon atoms arranged in a hexagonal pattern that looks like a honeycomb and rolling it into a cylinder with a diameter of a nm. That’s a carbon nanotube. It’s an incredible material: it has 400 times the mechanical tensile strength of steel at one sixth of steel’s density, and it has better thermal conductivity than a diamond. There are nearly endless uses for a material like that, which is why engineers are trying to figure out how to produce it cheaply.

Hydrogen atoms are really sweet romantic souls: they are partially-positive, and always on the lookout for a partially-negative oxygen atom to skip towards the sunset with. When these two meet it is love at first sight: they form a hydrogen bond. When this happens between amino acids, they are bound together and a long, twisted, rod-shaped alpha helix is created that repeats its structure every 0.5 nm. Alpha helices are the most common form of proteins and extremely stable.

What you see in this illustration is the length of one repetition of an alpha helix within a much longer spiral formation.