What if I told you that I could tell you your future?

That I could stare at you long enough and tell you exactly where you're going to be,

what you're going to be doing, who you'll fall in love with, what kind of job you'll have,

how you'll die, and even more.

I can tell you what your carbon and oxygen atoms will end up doing billions of years from now.

You'd probably wonder if you're listening to the right show, and the answer is you are listening to the right show because I can tell you your future. I can stare at you long

enough and tell you your entire future history. It's true. Why? Because this is physics and physics can

predict the future. If I'm studying a system, which system here is just a generic, vaguely

physicsy jargon word for a bunch of stuff

doing their own things, anything from a particle in a box to you.

Congratulations.

When it comes to physics, you are just a system.

If I'm studying a system and I know it's state, and state here's just a generic physics-e jargon word for the current status of the system, where all the particles right now in this slice of time, what they're doing, with their speeds and spins, and momentum, and positions, everything, just all the contents of that system.

If I know the system and it's state, then I can predict the future of that system. If I know the system and its state, then I can predict the future of that system. Why? Because this system evolves in time according to the laws of physics.

And the laws of physics tell us how one state evolves into another state, evolves into

another state, evolves into another state, evolves into another state, evolves into another state,

evolves into another state, evolves into another state, et cetera, I think you get the picture.

So if you are a system, and you are, and you're made of a bunch of physical stuff, and if the

laws of physics are correct, then I can simply crunch the numbers and tell you how

your state evolves with time. In other words, I can predict your future. This is called

determinism and it's kind of a big deal. And what's really cool about determinism is that it can be run in reverse. Time here, when it comes to physical systems in their states, in their evolution with time, time is just a parameter. It's just a number that steadily increases. And you see how the state changes as this thing called time changes.

But the thing called time in principle, not in reality, but you know, that's another episode

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