Bill Bryson uses the metaphor of a mattress to explain the counterintuitive notion of spacetime in Einstein’s relativity theory. Most people imagine that space is a vast, empty region in which our solar system (and everything else in the universe) resides. Relativity theory, however, posits that space and time are interwoven like a fabric, and that this comprises the structure of our universe. The mattress represents spacetime: if there’s a heavy object on the mattress that makes it sag, then any ball that’s rolled across the mattress won’t roll straight across, but rather toward the sagging part. This is what we perceive as gravitational pull. Gravity, in fact, is the effect of heavy objects warping spacetime. Bryson invokes this symbol to help the reader imagine and visualize this aspect of relativity theory, as he believes that science is much more engaging when it’s free of technical jargon and instead populated with visual metaphors like this one.
Mattress Symbol Timeline in A Short History of Nearly Everything
