Science Terms For Dummies

Cheat sheet

Science is real. Science is cool. Science uses a lot of terms that we all think we know. But, do we really know what we are talking about? In the spirit of scientific community and understanding, let's clear up some misconceptions around a few of the most misunderstood scientific terms. Let’s boldly go where no man has gone before.

Warning: You'll be hit with some pop-quiz questions and answers as you read through this list! Hope you studied!

And, if you think you're up on current science trending words and discoveries, take our real quiz to find out!

Pop quiz: Is it momentum or inertia that keeps you moving?

Here's a hint: In science, inertia is the property of matter that stays at rest or continues moving in a straight line, so long as it's not acted upon by an external force. As a side note, this is also Newton's First Law of Motion (file that away for trivia night).

Momentum is a term that describes the motion of an object equal to the product of its mass and its velocity. Saying something has momentum means it's moving in a specific direction and has a particular mass.

So, inertia describes an object's resistance to change in motion (or lack thereof), and momentum describes how much motion it has.

Pop quiz answer: Momentum is your force or speed of movement, but inertia is what keeps you going.

A force is an influence on a body or system, producing (or tending to produce) a change in movement or in shape of (or other effects on) an object. It's called a force regardless of how . . . forceful you're being.

Kicking a door open is you exerting a force on the door (a strong one). Politely opening the door in a normal way is also you exerting a force on the door (a gentle one).

The force, though, is totally different. To understand that, you’ll probably need to consult your local Jedi.

Pop quiz: Which of these (mass/weight/volume/density) would be different on another planet?

Here are some hints:

  • Your mass is the quantity of matter (which is just sheer stuff, in scientific terms) that you're made up of.
  • Your weight is a measure of the force of gravity on you.
  • Volume is the amount of space something occupies.
  • And, density is how tightly packed the matter is within said space.

Pop quiz answer: Your weight here on Earth is different from what it would be on the moon or Mars (both of which have lower gravity).

Your mass is the same no matter where you go because you'll still be made up of the same amount of matter. As for volume and density, assuming you take up the same amount of space on the moon or Mars, those should stay constant, too.

This isn’t a philosophical thing. Sir Isaac Newton—in his third law of motion—literally meant that “If object A exerts a force on object B, then object B also exerts a force of equal magnitude and opposite direction on object A.”

If a box exerts a force of 60 pounds on the ground, the ground is also exerting a force of 60 pounds on the box (to keep it from sinking). If you kick a ball, you’re exerting a force on the ball and the ball is exerting an equally-sized force back on you. If it didn’t, you’d just crush the ball and ruin the game for everyone.

Dictionary.com tip: Since this quote is specifically talking about physics, and since Newton himself was Christian, it doesn’t really make sense to quote Newton if you’re talking about the Hindu/Buddhist principle of karma. Sure it can sound similar, but they’re not really connected.

There’s a common misconception that gravity is a force that pulls you down toward the ground, no matter where the ground is. You'll see scenes in sci-fi movies where the artificial gravity fails and everything starts floating. Then, it gets fixed or comes back on and everything comes crashing down to the floor.

Those scenes are made of lies. There is no “up” or “down” in space. It’s way more likely they’d go crashing into a wall when the gravity came back.

Gravity on Earth is the force that pulls you and everything else on the planet toward Earth's center. It’s caused by a combination of the planet’s mass and its rotation (centripetal force). Likewise, the sun’s gravity pulls Earth into orbit around it, while the Earth also pulls the sun toward its core.

A long time ago, a physicist named Erwin Schrödinger proposed a thought experiment that was so weird it continues to haunt the internet to this day:

A cat is in a steel box with a Geiger counter, a tiny bit of radioactive substance, and a flask of cyanide. The radioactive substance has an equal chance of decaying or not decaying. If it does, it trips a mechanism that breaks open the cyanide, and the cat dies. Without opening the box to check, you obviously won't know whether this has happened or not, so there's an equal probability the cat is alive or dead. Therefore, you have to assume the cat is both alive and dead at the same time. (But, not as a zombie. That’s cheating.)

This hypothetical situation was designed to highlight a paradox in quantum mechanics where a particle is believed to exist in multiple states at the same time, but unless you observe the particle, you don't know for sure which state it's in. Therefore, until you observe, you must assume it's in all of the states.

No animals were harmed in the making of this experiment or slideshow.

  • It can't be emphasized enough that Schrödinger's cat was a thought experiment. There was no actual cat. There was no actual box. Sorry, internet.

Pop quiz: When something falls, does gravity give it velocity or acceleration? 

Hint: Velocity is the time rate that something is changing position (i.e., moving) in a specified direction. It's kind of like speed, but you're also required to specify direction. Acceleration is the time rate at which velocity is changing, with respect to magnitude or direction. It's how fast something is speeding up, slowing down, or changing direction.

As something falls toward the earth, its velocity changes at a rate of approximately 9.8 meters per second per second. This is known as the acceleration of gravity (thanks, Galileo).

Pop quiz answer: acceleration.

Nuclear (noo-klee-er) means “of, relating to, or forming a nucleus” (as in the nucleus of an atom). Nuclear fusion is a process where the nuclei of two small atoms are combined to form nuclei of bigger atoms. When this happens, it releases huge amounts of energy. This is the process that powers the sun.

Nuclear fission is the opposite: It’s when the nucleus of one big atom is split into the nuclei of several smaller atoms. This process also releases huge amounts of energy, as well as some radioactivity. It’s what happens inside nuclear-power reactors. Since the process obviously needs a big, heavy atom to get going, most reactors use uranium (which is one of the biggest ones available).

Not to be a downer, but we kind of need to mention bombs real quick: Atomic bombs use nuclear fission to create devastatingly big explosions. Hydrogen bombs explode in two phases: First they use fission, then amplify that by using fusion for a significantly bigger explosion.

Sonic means something is of or relating to sound. Contrary to what some hedgehogs (who shall remain nameless) would have you believe, it's not primarily about speed.

That being said: It is possible to go faster than the speed of sound (which is about 767 miles per hour, also known as Mach 1). As something accelerates, it builds up these invisible walls of air pressure in front of it. Kind of like the water that builds up in front of you as you swim. When you (or an aircraft) "break the sound barrier," you rip through that wall, and the result is a shock wave and a loud, sharp noise known as a sonic boom.

Interestingly, you've probably heard the sound barrier being broken before. Jets aren't the only things capable of it. If you ever hear a whip crack in the air, that sound comes from the tip of the whip going fast enough to break the sound barrier, creating a tiny sonic boom.

Mach 1 is exactly the speed of sound. Mach 2 is twice the speed of sound. Mach 5 would be five times the speed of sound (and so on).

Pop quiz: Which of these (ultraviolet/infrared) do you encounter on a day-to-day basis?

Here's a hint: Let's talk about rainbows and unicorns. A rainbow represents the full spectrum of visible light: red, orange, yellow, green, blue, indigo, and violet. It's in that order because that's how colors rank in terms of frequencies. Red light has the lowest frequency in the spectrum (longest wavelength), and violet has the highest frequency (shortest wavelength).

Ultraviolet (UV) means something sits above violet on the electromagnetic spectrum, just outside of the light humans can see. Ultra- even means "on the far side of, or beyond."

Infrared (IR) is the opposite of ultraviolet. Infra- means "below," which means infrared is electromagnetic radiation that's just below red on the spectrum. We also can't see it without help.

And, unicorns. They're cool, too. Not super scientific, but nice to think about once in a while.

Okay, this one was kind of a trick. Pop quiz answer: It’s both. The sun gives off both UV and IR radiation.

Everyone knows about the UV rays from the sun: They cause skin to tan, and in large doses they can cause some serious health risks. This is because UV rays have such a tiny wavelength they can penetrate your skin. Rude.

The sun also gives off infrared radiation, which you’ve actually seen examples of before. Think back to any science textbook or news article where you’ve seen a photo of the sun. Photos like that are taken with infrared. Because space is dark AF, there’d be no way to do that with visible light. This means you and the sun and other celestial bodies have something in common: Your body also emits infrared light in the form of heat, which is why you show up as a glowing blob in night vision.

Speaking of radiation, it is the process in which energy is emitted as particles or waves. It's worth knowing that radiation is all around us, and that not all of it is bad. Non-ionizing (low frequency) radiation includes things like heat, radio waves, visible light, and microwaves (the energy that heats your food, not the device itself). What's potentially not safe is ionizing (high-frequency) radiation, which has the power to affect living things at the molecular level.

Alpha particles are used in things like smoke detectors and can be blocked with a sheet of paper. Beta particles have some medical uses and can be blocked with stuff like aluminum foil, thin plastic, or a block of wood. Gamma rays and x-rays are higher energy/higher frequency and can pass through skin and wood. That property is what makes x-rays useful for . . . taking x-rays.

Gamma rays have the power to damage tissue and DNA. It's rare to encounter gamma rays, but they're the only ones you should really worry about.

You know that phrase light-years ahead? You hear it and most people think "Ah yes, it has the word year in it, so that must mean its several years ahead." Well, not exactly. Like the humble parsec, which was cruelly misconstrued by Star Wars decades ago, a light-year is a measure of distance, not time. One light-year is the distance traveled by light in one average solar year (because Earth scientists measure time in Earth years).

  • For the curious, that distance is about 5.88 trillion miles.

So, light-years ahead may not mean "years ahead," but it's still valid in the sense of "trillions of miles ahead."

As for the speed of light (which is about 186,000 miles per second in a vacuum): There's no denying it's really, really, ridiculously fast. In fact, it's the fastest thing in the known universe. You literally can't go faster than the speed of light.

Ready for that real quiz now?

Now that you've buffed up on your science terms for dummies, take our real quiz on current science trending words and discoveries to find out what you've really learned.

We bet you're not a dummy anymore.

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