Einstein’s Theory of Relativity does not preclude the development of a Time Machine.
A Time Machine may be possible, but it would be impractical.
The Universe is not static: everything in it is in constant motion.
Even if you were to create a ‘Time Machine’ it would kill you if you ever used it.
Even if you travelled to just one second in the past or future, you would find yourself in inter-galactic space with no air to breathe and no way to get back................
Not to be pedantic about it, but in 1 sec (counting earth’s rotational velocity vector, orbital velocity vector and the Sun’s galactic orbital velocity vector) plus assuming all vectors are aligned in the same direction (which they aren’t) gives you roughly 50 km of movement in 1 sec.
Earth’s orbital: ~29.8 km/s
Earth’s rotational: ~0.46 km/s at equator
Sun’s orbital: ~20 km/s
Not enough to reach intergalactic space, if the above numbers are correct.