SECTION

The Universe.

How does the cosmos really work?

Black holes, dark matter, the speed of light, antimatter and the search for a theory of everything—explained plainly, with the evidence labelled.

What Is a Black Hole, Really?

Not really holes and not cosmic vacuum cleaners, black holes are places where matter is packed so tightly that not even light can climb back out.

Established6 min read

Galaxies spin too fast and light bends too much, so something unseen seems to be out there, but nobody yet knows what it is.

Open question6 min read

In 1998 astronomers found that the universe's expansion is speeding up, and "dark energy" is the name for a cause nobody yet understands.

Open question6 min read

Shadows, stretching space and a famous neutrino scare all seem to break the cosmic speed limit. Here is why the limit still stands.

Established6 min read

The Big Bang should have left an almost empty universe. A tiny surplus of matter built everything we know, and nobody yet knows why.

Open question6 min read

Physicists have merged forces of nature before. Gravity is the holdout, and no candidate theory of everything has yet passed a decisive test.

Open question6 min read