On our fairly macroscopic level of perception, the universe is one of causality; things happen because of other things in a logical progression. On the subatomic scale, things are different of course. There reign probabilities and randomness. You may know in broad strokes what is going to happen, but detail cannot be refined arbitrarily. It’s like how we can know that a coin flip will result in either heads or tails, and that – over time – the amount of tails will equal the amount of heads, but not being able to predict in each instance which outcome will occur.
Well, if we indeed live in a clockwork universe at our level, we probably could predict the outcome, if we had data on every atom in the coin and the table, how fast they are moving and in which direction.
However, this would only work if it was a completely isolated system. If someone suddenly comes into the room, altering air currents, temperature, pressure and so on, our model would be slightly off. Perhaps not to a great significance, but still.
And ensuring a completely isolated test environment is kind of impossible, since a burst of gamma rays might be heading our way right now to cook our brains in our skulls. Since information can (probably) not be sent faster than the speed of light, we could never know before the interference had already happened.
But let’s say we scale it up to the size of the universe. Surely that is a closed system? Kind of probably, yeah. Let’s just say it is; I mean, we’re assumimg shit left and right already.
So if we had information (mass, momentum, direction of movement, etc) on all the particles in the universe, then we could predict our coin toss. We could in fact predict everything.
There is of course a big problem here; where do we store the information about all the particles? If we store it in some gigantic computer, then that computer is part of the universe and would have to contain information about itself as well. How can something contain itself? Perhaps if we compress the data? Well… The problem is just bumped a step. The memory banks would still have to contain the configuration of all the atoms the memory banks are made of, which would change according to what you stored, which would change with the configuration…
And so on.
Point is, you can’t save all the information about the universe inside this universe. Well, you can, actually; just look at the universe as a memory bank describing itself. That’d work. But where then would you put the program, the algorithms? You’d need some sort of rules, and those rules would have to perfectly mirror the laws of nature. Things is… if you consider the universe to be a memory describing itself, then the laws of nature in that universe already are reshaping the data.
So you could say that the universe is in fact running a simulation of itself.
Oh boy! It’s just like those far-too-frequent moments during math tests when I used to prove that x = x.
No matter how much we learn and know, we will never be able to predict the future completely, because the only way to make predictions about anything is to isolate the system and pretend like you can watch anything while it’s completely cut off from you.
No wonder weather forecasts are so hard to make.