Eli5: Why does gravity work? Like I get what it is but why does gravity exists?


Eli5: Why does gravity work? Like I get what it is but why does gravity exists?

In: Physics

Like most things, it doesn’t have a reason for existing but rather just is. Even if we find and prove the existence of some other thing that causes gravity (such as curvature of spacetime, the currently preferred explanation), then that thing will have no reason to exist.

We don’t know *why* it exists.

There are interesting philosophical arguments that if some aspect of the universe wasn’t the way it is, we couldn’t exist, but that doesn’t really explain why. Like a fish could ask “why does water exist?”. If it didn’t, the fish asking the question couldn’t exist. But that’s not really a good answer to why water exists.

There are cool mathematical models of universes that are very different from our universe, and some may have no gravity. But a cool concept may not (and probably doesnt) answer the question either.

It would take a physics theory which gives gravity (and all the other basic aspects of the universe) plus a way to prove that it is the one correct theory of the universe. That probably will never happen.

Jeeronian is right. Gravity is one of the fundamental forces of the universe and it exists because it exists. Sometimes you just have to accept things like that.

Anthropic principle.

If gravity didn’t exist, we wouldn’t either, so you wouldn’t be here to wonder about it.

I.E. Don’t worry about it!

Ignore the other commenters that say “there is no why.” .

In the standard model of physics there are a bunch of parts that are mathematically dependent on each other. What this means is if one number was even slightly different, the whole system could not work (ELI5). So gravity exists as one of several factors necessary for a balanced system. It would be similar to a nuclear decay where a neutron turns into an electron and a proton and asking “why is there an electron?” [ELI5] Or if you took apart a BLT and asked “why are there tomatoes?” It’s a necessary part to complete the set.

Now we can imagine some other arbitrary system of numbers that also happens to balance out, but gravity and the other mathematical constants like magnetism and the strong nuclear force already exist as a balanced set in the world we live in. The “big bang” is some kind of [preceding event where these forces were merged together and broke apart](https://openstax.org/resources/96e3d538be70bcf75a7c459302ab50e08e4294a5); so in this case the big bang is the BLT and gravity is tomatoes.