Everything is made of matter, not antimatter, including black holes. If antimatter black holes existed, what would they do?

Do the laws of physics place a hard limit on how far technology can advance, or can we re-write those laws?

At four million solar masses, the Milky Way's supermassive black hole is quite small for a galaxy its size. Did we lose the original?

Time isn't the same for everyone, even on Earth. Flying around the world gave Einstein the ultimate test. No one is immune from relativity.

The idea of black holes has been around for over 200 years. Today, we're seeing them in previously unimaginable ways.

Popular media often frame scientists as having a cold, sterile view of the world. That couldn’t be further from the truth.

Astronomers in 2017 caught an image of a supermassive black hole in a galaxy far, far away. Doing it in our own galaxy is a huge milestone.

After years of analysis, the Event Horizon Telescope team has finally revealed what the Milky Way's central black hole looks like.

In Sun-like stars, hydrogen gets fused into helium. In the Big Bang, hydrogen fusion also makes helium. But they aren't close to the same.

We have long thought that Pluto was completely frozen solid, but the discovery of cryovolcanoes challenges that assumption.

Speculation about the existence of aliens goes all the way back at least to the Greek philosophers. Their arguments will sound familiar.

Could we finally detect the elusive Unruh effect?

Everything that gets heated up has to, somehow, radiate that energy away. Here's what we see when that happens in the Universe.

For a thousand light-years in all directions, there's a "bubble" that the Sun sits at the center of. Here's the story behind it.

Europa may be difficult to access. But if a recent study is correct, its subsurface ocean would be more accessible than previously thought.

Most potentially hazardous asteroids remain unidentified. NEO surveyor could change that, but only if it's funded, and soon.

Extremely precise atomic clocks are not just of theoretical interest; they could help detect impending volcanic eruptions or melting glaciers.

All life forms, anywhere in our Universe, are chemically connected yet completely unique.

Was there ever life on Mars? Is there life on Mars now? Did it originate there or here, on Earth? All possibilities are fascinating.

Look out at a distant object, and you're not seeing it as it is today. It's size, brightness, and actual distance are all different.

It was supposed to have a 5.5-10 year lifetime, and take 6 months to calibrate. It's performing better than anyone anticipated.

If there are human-sized creatures walking around on other planets, would we be able to view them directly?

There are pros and cons to sending interstellar messages to aliens that may or may not exist.

Singularities frustrate our understanding. But behind every singularity in physics hides a secret door to a new understanding of the world.

It didn't look like anything I'd seen before, but I'd be a great fool to consider "aliens" as a reasonable possibility.

We take for granted that time is real. But what if it's only an illusion, and a relative illusion at that? Does time even exist?

When the Hubble Space Telescope first launched in 1990, there was so much we didn't know. Here's how far we've come.

Spin, spin, spin — fire! The startup’s radical system could make satellite launches cheaper and cleaner.

Ancient helium-3 from the dawn of time leaks from the Earth, offering clues to our planet’s formation. A key question is where it leaks from.

Spirals, ellipticals, and irregulars are all more common than ring galaxies. At last, we know how these ultra-rare objects are made.