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They call it the "fabric of reality" because that's a good metaphor to describe how gravity works. (Or at least I assume that's where it came from, I could very well be wrong.)
When you stretch a fabric thin, and place something heavy in it, it's going to sink and stretch the fabric down with it. Then, if you place a smaller object next to the larger one, it's going to roll around the larger one, gradually moving closer as it goes down the slope created by the larger object.
That might be hard to visualize, so here's a neat video I found.
Edit: guys I think you're reading too much into this I wasn't trying to provide a foolproof explanation of how gravity works I was just trying to relate an interesting metaphor to a piece of linguistics.
And I wasn't even right, a quick google search says the term predates our understanding of the universe. Its probably a coincidence.
It's worth noting that spacetime isn't static. Space "flows" into mass. It's akin to a treadmill, you need to constantly move "upwards" to stay in place.
This is also the reason that uniform gravity, and acceleration are identical. With acceleration, the "ground" is constantly moving upwards into new space, pushing you along. With gravity, space is constantly moving down through the floor, trying to push you into the floor. It's functionally the same thing.
That's a really interesting perspective. I don't think I've ever seen it described that way before, but it's very easy for me to grasp. Do you have any resources I can look into for more information? Does that concept have a name I can look up?
It was the initial description used in my 1st year physics degree course. Not sure if it has an explicit name. We also jumped fairly quickly from there to the maths.
Basically space time can stretch infinitely, and flows towards mass. Anything on that spacetime is drawn along. It's functionally identical to a standard force. Straight lines twist into spacetime spirals (aka orbits etc).
Physics has lots of interesting mental models for different things. Unfortunately, most are flawed, so dont lean on tgem too hard. What actually happens is way beyond what our monkey brains can interpret. The best we can do if follow the maths, and try and fit something to the end result.
Yeah, I'm aware that all or numbers and models are, at best, representative of what is really happening. That's what I love about the limits of our knowledge: there always something more to learn.
I wonder how spacetime around a black hole's ergosphere is represented by the "flow" analogy. Maybe like water swirling around a drain?