Brian Greene - The Mind-bending Physics Of Eternity | Modern Wisdom Podcast 308

When you realize how unlikely it is that collections of particles would come together to yield a living system called a human being, and how spectacular it is that this collection of particles called a human being can invent, manufacture notions of value and meaning and purpose, how spectacular is that? (wind blows)

Brian Greene, welcome to the show.

Thank you.

Thank you for being here. I am a massive fan of your work. I'm very, very glad that you're joining me today.

Oh, thank you. That's great to hear.

We hear a lot about the big bang and the beginning of the universe 13 and a bit billion years ago, but I wanna start at the end. Have you got any predictions for the end of the universe? If the big bang is when time began, then when will time stop?

Well, we don't know. But there certainly are ideas that people have developed, so it's not as though we're just shooting in the dark. The most straightforward interpretation of the data and the mathematics suggests that the universe may continue to expand forever. Forever's a kind of funny concept. It's an idea where time wouldn't literally end, but en route to that eternity, everything that we know about will end. Every star will end, every galaxy, every planet. Matter itself will, according to some of our cutting-edge theories, disintegrate into a spray of more refined particles, electrons, neutrinos, that will just continue to waft through that ever-expanding cosmos. So we don't know that that's how things will end up, but if you were to ask me to place bets, based on what we know today and what we've observed today, that would probably where the bulk of my money would go.

Is that what's referred to as the big freeze?

It is, because the universe will just continue to get ever colder as it gets ever larger. And weirdly enough, it's also referred to as the heat death. It seems to be a kind of tension between the big freeze and the heat death. But they're actually the same thing, because the idea is that you'll reach a kind of equilibrium, where every place in the universe will come to the same temperature, and it's that equal distribution of heat that is what we refer to at the heat death. But, but the temperature, the common temperature will be so low that you can also think of it as a kind of big freeze.

What is a way that people can wrap their heads around how far away from us that is now?

Uh, that's a tough one. I, I have a metaphor that I like to use when taking people on a journey toward the far future. I use the Empire State Building in Manhattan, where I envision that every floor is 10 times the duration of the previous floor in this sort of poetic representation. So the ground floor is one year, the next floor, 10, the next floor, 100. So it's an exponential scale, where 10 to the floor number is representing the year that you're on at a given floor. And that approach takes you to 10 to the 100 years into the future. Today, we're 10 to the 10 years from the big bang, so we're on the 10th floor. So everything that we know about from the big bang till today only gets to the 10th floor, and exponentially far into the future as you climb. Now, by the time you reach 10 to the 100 years into the future, we'd be en route, if the ideas that we currently have are correct, we'd be en route toward that heat death. We'd be en route toward that big freeze. But again, if it keeps on going forever, then even the 100th floor of the Empire State Building, 10 to the 100 years in the future, at some point, that will be a mere blink of an eye en route to the (laughs) timescales that we'll ultimately encounter. So it's hard to have a metaphor. It's hard to have an image, but I think the Empire State Building and that exponential growth at least takes you part way toward the incredibly long timescales that we're talking about here.