I need help with an analogy here because I simply don’t know/can’t visualise the true physics here.
Many people use an analogy for gravity acting on space-time as a sheet of material stretched across a plane and a heavy object in its center acting as a celestial body.
This is great for envisioning orbits, the curvature of spacetime and so on.
Now this is a “2D” sheet/plane that deforms “downward” in the 3rd dimension, I get it… But how does it translate to the actual universe? The universe is always 3D in all directions, isn’t it?
I’m stuck here guys, science help me!
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It’s really tricky to get your head around. Even physicists have a hard time with this unless they are looking at the maths.
How I try to get my head around it is instead of a flat sheet of rubber, think of a giant sponge. You are in the center of the sponge and pull the sponge material toward you to make a dense little point from all directions. The point you make is the center of mass of the object you are trying to represent. That point can be very dense (an object with a lot of mass) but as you look at the sponge, the further away from that point the less dense the sponge is. And it will describe a sphere in the sponge that is getting less and less dense the further you get away from the center.
Now if try to move through the sponge your path will curve depending on how close you are to the “center of mass”
It’s not perfect, but it can help visualize it in 3D.
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