Steven Weinberg on Space

STEVEN WEINBERG ON SPACE

Posted November 10, 2011

What is space? Oh my god, I wish I had known you were going to ask that... That's hard to... Asking a person what is space is a little bit like asking a fish what is water. It's something we are so used to that it's hard to put into words.

Space can have something in it, or it might not. Aristotle thought that, in fact, there was no such thing as space without something in it, that that was a contradiction of terms. Well, today we don't think that way. In fact, even before Aristotle, Democritus thought that space was emptiness, and here and there there were atoms that banged into each other. But atoms in the void was what made up nature.

We lean today toward the view of Democritus rather than Aristotle. Space is mostly empty, and here and there there is stuff, and the stuff in our present universe mostly takes the form of atoms. In the very early universe it wasn't atoms, it was elementary particles, and in the very, very early universe it wasn't even elementary particles. It may have been just some kind of diffused energy filling the universe.

But even what we call empty space is not really, from a certain point of view, empty, even though there may not be any particles in it. There are fields, like the gravitational field, the electromagnetic field. So that from the point of view of modern physics, quantum mechanics, empty space is only empty in the sense that it may not have any particles in it but will always have fields in a continual state of fluctuation.

AUDIO

Produced by

David Levin

Original Interview by

Rush DeNooyer

IMAGE

(Steven Weinberg)

© WGBH Educational Foundation 2011

Major funding for "The Fabric of the Cosmos" is provided by the National Science Foundation and the Alfred P. Sloan Foundation.

Additional funding for this program is provided by the Arthur Vining Davis Foundations.