Photo by Hassaan Qaiser on Unsplash

We have made a couple of posts lately about scientific concepts that we don’t really understand (here and here). I don’t know if this will be an ongoing thing or not, but I decided to add to it with a little bit about gravity.

Gravity is one of those things that, according to my teachers and textbooks, I understand. I took a college level physics class. I can say a bunch of things about it. Anything with mass has gravity. The more mass, the more gravity. The closer two objects are, the stronger the attraction. On Earth, things fall at 9.8 meters per second squared. But, if we’re being real, none of that gets me any farther than, “What goes up must come down.”

What is gravity? Above, I described some of the effects it has, but what is it? How does mass have gravity? Does mass have gravity? Or does mass create gravity? Is gravity its own thing or is it part of things with mass?

I’ve often seen the picture that’s supposed to show how gravity works. The one where it looks like every object in outer space is actually sitting on a huge trampoline. The more massive the object, the bigger the indentation in the trampoline. I think the trampoline is supposed to be space-time and as things get near an indentation, they fall into it. But that doesn’t make any sense to me. Is space-time two dimensional like a trampoline? If not, how can it have indentations? And why would objects fall into the indentations? Isn’t that question begging? It also implies that there is a limit to gravity’s reach, but I’m told that’s not the case.

And that’s a whole other thing. Whenever I read anything about quantum physics, I invariably run across Einstein’s famous complaint about “spooky action at a distance” with quantum entanglement. But my understanding is that Einstein is the guy who really figured gravity out with General Relativity and such. If it’s true that every single object in the universe is constantly pulling on every other object in the universe, how is that not spooky action at a distance? Why is it fine for gravity, but not quanta?

I suspect I’m not the only one who finds it bewildering. It’d be great if someone could explain it to me. We need to stop settling for explanations that don’t explain anything. Unless no one actually knows what it is or how it works. Maybe they can just describe what happens and there is no real explanation. That would be awfully disappointing.

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