When an invisible entity making up 85% of the universe's mass stumps the greatest scientific minds of our time, awe is an understandable response.

Do constants of nature—the numbers that determine how things behave, like the speed of light—change over time as the universe expands? Does light get a little tired traveling vast cosmic distances? It ...

Modern cosmology assumes dark matter exists. But what makes us so certain that dark matter is the answer—and what if we're wrong?

This is read by an automated voice. Please report any issues or inconsistencies here. Physicists studying dark matter — an invisible substance comprising 85% of the universe — turn to religious and ...