## What Is Spacetime in Einstein Theory

Published: July 2, 2024

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the laws of physics and the speed of light must be the same for all uniformly moving observers, regardless of their state of relative motion.

For this to be true, space and time can no longer be independent. Rather, they are “converted” into each other in such a way as to keep the speed of light constant for all observers.

(This is why moving objects appear to shrink, as suspected by FitzGerald and Lorentz, and why moving observers may measure time differently, as speculated by PoincarĂ©.) Space and time are relative (i.e., they depend on the motion of the observer who measures them) and light is more fundamental than either.

** Note: I don’t have intuition about spacetime in Einstein theory. **

#### What is spacetime in Einstein theory ?

- It’s like all objects in the universe sit in a smooth, four-dimensional fabric called space-time.
- This fabric is curved by the mass and energy of objects in it.
- The curvature of space-time causes objects to move on curved paths. We see these paths as the force of gravity.
- This fabric is not just space and time, but a combination of both. It’s like a 4D fabric where 3D is space and 1D is time.

Now to me this fabric thing confuses me. This just doesn’t feel right to me.

Reference:

- https://einstein.stanford.edu/SPACETIME/spacetime2.html
- https://www.space.com/end-of-einstein-space-time

It will help me to improve/learn.