Brian Greene

In the decades that ended in the mid 1920s, Scientists did work that resulted in a fundamental understanding of the world like we never could have before.

The contributions of quantum mechanics stand on their own. People don’t understand the basics of quantum mechanics. He showed some examples of “quantum” being misused. He’s going to try and give us the basics of quantum physics.

Quantum Sleeper

Here’s how it goes: quantum mechanics is based upon one concept and one imaginative leap. The concept is waves, how they move and interact. Whenever you see data that looks like bright band, dark band, an interference pattern, it tells you that you’re dealing with a wave phenomenon. If you have a bb machine gun and fine it a two slits, the BBs stick in two lines aligned with the two silts. If you fire electrons through the same wall, you see a wave pattern. What does that mean?

There must be some sort of wave associated with particles. But waves of what? These are individual pellets, where could the wave idea come into the story. Here’s the imaginitive leap, mid 1920s, people are struggling with this data. The wave associated with a particle must be a wave of probability. We are used to a reality where things are definite. You can predict what will happen. This introduction into probability into the laws of physics, is a radical departure from any way of thinking about physics or reality.

Why is it so unfamiliar if underlying everything is a probabilistic under bearing to everything around us. For a large object there is a spiky probability curve, you’re 99.999% certain the ball will follow Newton’s law. If you measure an electron you have a spiky probability wave, but an instant after that the location it goes to just becomes a much flatter set of probabilities, until you measure it again.

Every particle in a world has something called spin. Einstein found a “spooky” action, you could measure a particle and if it’s spinning up its mirror particle that could be thousands of miles away the other one will spin down at exactly that moment. A non-local interaction between distant objects.

Quantum computing, people are trying very hard to make use of the spread out nature of quantum mechanics. One particle to do many calculations at the same time. Final thing, if you think that any of this stuff feels esoteric, bear in mind, your personal computer, your cell phone, everything you see around us is based on the integrated circuit, which you wouldn’t have without quantum mechanics. Not only does this change our understanding of the nature of reality.

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