What is Quantum Mechanics?

Live Science

Astrophysicist Paul Sutter explains Quantum Mechanics - the body of scientific laws that describe the wacky behavior of photons, electrons and the other particles that make up the universe.

Transcript

00:00Quantum mechanics is our fundamental framework for understanding the physics, the behavior

00:07of the very, very small.

00:09I'm talking like atoms, molecules, and subatomic particles.

00:15I'm Paul Sutter and this is Paul Explains, the show where I, you know, explain.

00:23There's three big pieces to quantum mechanics.

00:27One of the pieces is in the name itself, this idea of quantization, that certain properties

00:36of subatomic systems like energy or angular momentum come in discrete levels or packets

00:45or what we call quanta, hence the name quantization.

00:49For example, an electron in an atom can't have any old energy that it feels like.

00:57No.

00:58It can have only certain energy levels.

01:01That's because the energy levels in an atom are quantized.

01:04This is a fundamental core tenant of quantum mechanics and it's very different than the

01:10physics of the macroscopic world.

01:13Another key component of quantum mechanics is something we call wave particle duality,

01:18where tiny things sometimes act like particles, like tiny little bullets, tiny little billiard

01:25balls, tiny little ping pong balls bouncing around doing everything that particles do and

01:31sometimes also act like waves where they're more sloshing around or they interfere with each

01:38other.

01:39So depending on what you're looking for and how you're looking for it, sometimes, sometimes

01:45it might act like a little bit of both.

01:48And the last bit is that quantum mechanics and subatomic systems are ruled by probabilities

01:55and uncertainty.

01:56Up here in the macroscopic world, if you can know exactly where something is and exactly

02:02how fast it's moving, and you can predict, using the laws of physics, exactly where it's

02:08going to be, exactly where it's going to go.

02:10But you don't get that kind of precise knowledge in the subatomic world.

02:17You don't always know exactly where something is, like an electron.

02:20You don't always know where an electron is or how fast it's going.

02:25And once you do know where it is, or at least have some idea, you don't know exactly where

02:31it's going to go.

02:32Instead it's going to be a range of probabilities.

02:36Our understanding of quantum mechanics underlies so many things.

02:43Atomic and nuclear power, all of that is thanks to our understanding of quantum mechanics.

02:48Microchips, semiconductors, lasers and LED, and even biology.

02:54So a bunch of physicists playing around in the early 20th century gave us this major cornerstone

03:01of many fields of science.

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