Question: how can you predict the future and think its right?

Scott Melville answered on 14 Nov 2017:

Good question!
Imagine you flipped a coin, and it came up heads. Then you flipped it again, and it was still heads. So you keep flipping, and you keep getting heads. After about 100 heads in a row, you’d probably be pretty convinced that the next toss was also going to be heads, right? What about 1000 heads? Or a million heads? Then you’d be almost CERTAIN that the next toss was going to be heads too.
This is essentially what science does. I predict that the Sun will rise tomorrow morning. Why? Because in all of the millions of previous mornings, the Sun has always risen – so it’s almost certainly going to rise tomorrow as well. That’s why we do experiments – we try to find patterns in how things behave (like a dodgey coin or the Sun), and then repeat them over and over again to make sure that we got the pattern right.
We can do a very similar thing when we simulate the whole Universe. I start by telling my computer some simple rules about how things should interact with each other, and then just leave it with a bunch of matter to see what happens. All the matter clumps up into nice galaxies and clusters – just like the Universe we live in today. We do this over and over again, many millions of times, and EVERY time the matter clumps up in a way very similar to our Universe. So that’s why we think that those simple rules are almost certainly correct – for the same reason we think that the Sun will come up to tomorrow: it just always does 🙂