In the 19th century, scientists were working under the presumption that the universe was stable and, for practical purposes, infinite in all directions. They believed matter moved through a field that gave it form. They called this field an aether.
Then Einstein came along and discovered a way to calculate relativistic mechanics without the need for an aether. Einstein’s theory was subsequently backed up by experiments that seemed to show there was no aether of the type scientists had once presumed existed.
At the time Einstein first proposed his theories of bending space and relativity without an aether, he did not believe in a “Big Bang” expanding universe. The Big Bang was actually the brain child of a Catholic priest. It wasn’t until Hubble came along and showed that the spectra of distant galaxies seemed to shift toward the red end of the light spectrum in proportion to their brightness that Einstein finally conceded that the universe may actually be the product of a “Big Bang.” However, in the decades that followed, a mountain of contradictory evidence has been accumulating that undermines these assumptions.