Fascinating. All the universe is math.
Source: reddit.comThe curvature of spacetime is described by a type of object called a field - which really just means it’s a set of numbers (matrices, in particular) with some value at each point in space and time, each saying how much curvature there is in various directions. There are lots of other fields - the electromagnetic field is a famous one - and while the spacetime field is certainly special, since it describes the background that all the other fields move on, it’s nonetheless the same kind of thing fundamentally.
Quantum theory tells us that fields and particles are inextricably linked - particles are nothing other than energetic excitations in a field. So just as the excitations or ripples in the electromagnetic field give rise to electromagnetic waves, or photons, so we expect the gravitational field to give rise to particles called gravitons. We already know half the story, we know that spacetime has classical (i.e., non-quantum) ripples called gravitational waves that are very much analogous to electromagnetic waves, and we know that when you throw quantum mechanics in the mix, the electromagnetic waves become photons.
But there are various technical difficulties with taking Einstein’s theory of spacetime and making it work as a quantum theory. As I said, they’re quite technical, but they have to do with the fact that at higher and higher energies, the theory “blows up” and starts spitting out infinities, making it impossible to calculate anything.
