Before discussing more about the expansion of the space-time fabric, want to discuss what exactly is the space-time fabric?
In physics, spacetime is a mathematical model that combines the three dimensions of space and one dimension of time into a single four-dimensional manifold. Spacetime diagrams can be used to visualize relativistic effects, such as why different observers perceive differently where and when events occur.
The fabric of space-time is a conceptual model combining the three dimensions of space with the fourth dimension of time.
Nowadays, when people talk about space-time, they often describe it as resembling a sheet of rubber. This, too, comes from Einstein, who realized as he developed his theory of general relativity that the force of gravity (opens in new tab) was due to curves in the fabric of space-time.
Although we can discuss space-time as being similar to a sheet of rubber, the analogy eventually breaks down. A rubber sheet is two dimensional, while space-time is four dimensional. It’s not just warps in space that the sheet represents, but also warps in time.
This rubber sheet model allows us to visualize how light is bent by gravity due to the curvature of the sheet.
One common way to visualize the geodetic effect is to think of Earth as a bowling ball and spacetime as a trampoline. Earth’s gravity warps spacetime the same way a bowling ball weighs down the middle of a trampoline.
According to Einstein’s General Relativity Theory,light will be affected in the same way matter is affected by gravity. This is because under this theory, we should think of gravity not in terms of vector like forces, but as a consequence of the “shape” of the universe.
But, though we can model and understand space-time as a “fabric”, it does not mean there is actually a “fabric”. It is only a mathematical model.
When Einstein concocted his general theory of relativity, one of the great advances was to recognize that space and time were combined into a single entity: spacetime. Another was that the presence of matter and energy curved the very fabric of this spacetime, and that curved spacetime, in turn, dictated how matter moved.
As ubiquitous as pictures of bent sheets or coordinate systems are, they aren’t exactly reflective of the reality we inhabit.
But under no circumstances should you conceive of space as though it’s a material, physical thing; it isn’t. This is only a mathematical structure that we can write down equations to describe: the equations of Einstein’s General Relativity. The fact that matter and radiation respond to that curvature in the exact ways that the equations predict validates this theory, but it doesn’t mean that space is actually a fabric.
“The space time fabric is a mathematical abstraction which doesn’t exist as such.”
https://socratic.org/questions/what-is- … made-up-of