What’s a day to a mayfly?
What’s a decade to a man?
What’s a millennium to the universe?
It’s time to put time in perspective with this awesome graphical journey from Wait But Why. <- Start there, and then we’ll continue our adventure.
Our brains have a hard time putting the immense scale of Time (as in “all of it”, which is why it’s capitalized) into perspective. We’re just not built for that kind of thing. While we’re at it, scales of size throw us for a loop too.
That scale of that time, be it seconds, years or atomic oscillations of cesium atoms, is just the construction of humans, signposts along the way so that we can mark how different now-now is from then.
But wait, is now inherently different from then? Yes. That’s where time comes from in the first place. Time only moves in one direction. There’s a reason that the universe can not be reversed, a rule that makes today different from yesterday.
The arrow of time points forward. As long as the universe is getting messier, time will continue to tick on. Entropy, man. All the things are in a more disordered place than they just were, just then.
Life itself depends on the fact that the universe is not in thermal equilibrium. There are simply many more ways that matter can be disordered than it can be organized neatly, and our biochemical reactions take advantage of that. Be thankful for entropy.
Like Brian Cox says, there are more sand dunes than sand castles. I mean, probability says sometimes you’ll get a sand castle spontaneously forming on the beach, but you’ll get a gazillion random piles of sand in the meantime. So entropy marches on, and the universe gets disordered, and new nows become different from just thens.
Then why isn’t our world just some strange exception among the mess?
If ordered piles of molecules named Joe are just some rare, low-probability fluctuation in a universe that would much rather be in all kinds of disordered non-Joe-ness, then why does so much of the universe seem to look organized? I mean, there’s you, and there’s the rest of Earth, and the rest of everything. Why isn’t this the only planet, star, galaxy, etc?
Well, maybe we’re only a chicken that’s come out of a larger egg. Maybe we’re not a closed system. Maybe, there’s more beyond this universe?
That’s Sean Carroll’s idea anyway. Well, it’s not just his, but here he is talking about it in rather entertaining form at TEDxCaltech:
If any of this time business turns out to be too stressful, there’s a way out. But there’s a catch, it involves moving close to the speed of light. And if you dilate yourself out of this time scale, you’ll leave all of us behind, and we don’t want to see you go. Unless you take us with you. It’s that pesky twin paradox:
Gotta stop now. I’m out of time.