Thus all theories which assume a constant view of time or space have been physically invalidated. Einstein's theory has been shown to hold in many different situations, and tested up to speeds very close to that of light in particle accelerators. The closer an object travels to the speed of light, the slower its internal clock goes. The very highest energy particles that we know of take 5 minutes of their own time to traverse the width of a galaxy, while an observer at rest with respect to the galaxy sees them take several thousand years. To the particles, space and not time has been distorted they see the whole enormous width of the galaxy compressed by a factor of a billion.
Gravity can also have a dramatic effect upon space and time.
The tremendous gravity produced by black holes and neutron stars means that time slows down in their vicinity, and light no longer travels in straight lines but bends to follow the warped curvature of space. Philosophers also have difficulties with the notion of the passage of time. We find it natural to think of time as flowing, of ourselves as moving through time. But this suggests that time could flow quicker or slower than it actually does, that we might move more or less quickly through time. One unpromising suggestion is that there is a second-order time, within which time flows more or less quickly.