“Science, however, gives me the feeling of steady progress: I am convinced that theoretical physics is actual philosophy. It has revolutionized fundamental concepts, e.g., about space and time (relativity), about causality (quantum theory), and about substance and matter (atomistics), and it has taught us new methods of thinking (complementarity) which are applicable far beyond physics.” -Max Born
The farther away we look in the Universe, the farther back in time we look as well, since light has a finite speed. But if a galaxy’s light takes a million years to reach you, that galaxy is going to be farther away than a million light years by time that light arrives, because the fabric of the Universe itself is expanding.
This leads to a puzzling fact of nature: even though the Universe is 13.8 billion years old (since the Big Bang), the most distant galaxies are upwards of 30 billion light years away, with the current record sure to be broken in the coming years.