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,

00:06the behavior of the very very small. I'm talking like atoms, molecules, and

00:12subatomic particles. I'm Paul Sutter and this is Paul Explains, the show where I,

00:19you know, explain. There's three big pieces to quantum mechanics. One of the

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

00:35of subatomic systems like energy or angular momentum come in discrete levels

00:44or packets or what we call quanta, hence the name quantization. For example, an

00:50electron in an atom can't have any old energy that it feels like. No, it can

00:57have only certain energy levels. That's because the energy levels in an atom are

01:03quantized. This is a fundamental core tenant of quantum mechanics and it's very

01:08different than the physics of the macroscopic world. Another key

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

01:17where tiny things sometimes act like particles, like tiny little bullets, tiny

01:25little billiard balls, tiny little ping pong balls bouncing around doing

01:28everything that particles do, and sometimes also act like waves, where they're more

01:35sloshing around or they interfere with each other. Depending on what you're looking

01:41for and how you're looking for it, sometimes, sometimes it might act like a

01:46little bit of both. And the last bit is that quantum mechanics and subatomic systems

01:52are ruled by probabilities and uncertainty. Up here in the macroscopic world, if you can

01:59know exactly where something is and exactly how fast it's moving and you can predict,

02:05using the laws of physics, exactly where it's going 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. You don't always know where an

02:21electron is or how fast it's going. And once you do know where it is, or at least have some idea,

02:29you don't know exactly where it's going to go. Instead, it's going to be a range of probabilities.

02:36Our understanding of quantum mechanics underlies so many things. Atomic and nuclear power,

02:44all of that is thanks to our understanding of quantum mechanics, microchips, semiconductors,

02:50lasers and LED, and even biology. So, you know, a bunch of physicists playing around in the early 20th

02:57century gave us this major cornerstone of many fields of science.

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