It's not too often that a giant of physics threatens to overturn an idea held to be self-evident by generations of physicists. Well, that may be the fate of the famous Penrose Singularity Theorem if we're to believe a recent paper by Roy...

There are four fundamental forces - the strong and weak nuclear forces, electromagnetism, and gravity. Except maybe gravity is no more fundamental than the force of a stretched elastic band. Maybe gravity is just an entropic byproduct—an...

So you’ve decided to jump into a black hole. Good news: as long as the black hole is big enough you can sail through the event horizon without harm and get to experience the interior of the black hole before you’re annihilated by the...

Meet Alice and Bob, famous explorers of the abstract landscape of theoretical physics. Heroes of the gerdankenexperiment—the thought experiment—whose life mission is to find contradictions in the deepest layers of our theories. Today our...

Black holes are inevitable predictions of general relativity—our best theory of space, time and gravity. But they clash in multiple ways with quantum mechanics, our equally successful description of the subatomic world. One such clash is...

The primary characteristic that defines black holes is in the name. Black holes are black. The gravitational pull at the event horizon is so powerful that not even light can escape. In this case, black means absence of light. We also...

If you track the motion of individual stars in the ultra-dense star cluster at the very center of the Milky Way you’ll see that they swing in sharp orbits around some vast but invisible mass—that’s the Sagittarius A* supermassive black...

Here’s the story we like to tell about the beginning of the universe. Space is expanding evenly everywhere, but if you rewind that expansion you find that all of space was once compacted in an infinitesimal point of infinite density—the...

Hollywood (and other fictional media) loves to show people dying in outer space. And it has several go-to causes of death, on a sliding scale of accuracy. But it turns out, reality has some ways to kill you that are far stranger than...

If there’s one thing cooler than a black hole it’s a rotating black hole. Why? Because we can use them as futuristic power generators, galactic-scale bombs, and portals to other universes.
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Black holes are self-sustaining...

From Stargate to Interstellar, wormholes are our favorite method for traveling across fictional universes. But they are also a very serious field of study for some of our greatest minds over the last century. So what’s the holdup? When...

The Nobel prize in physics this year went to black holes. Generally speaking. Specifically, it was shared by the astronomers who revealed to us the Milky Way’s central black hole and by Roger Penrose, who proved that in general...

Normal maps are useless inside black holes. At the event horizon - the ultimate point of no return as you approach a black hole - time and space themselves change their character. We need new coordinate systems to trace paths into the...

The holographic principle emerged from many subtle clues – clues discovered over decades of theoretical exploration of the universe. Over the past several months on Space Time, we’ve seen those close clues, and we’ve built a the...

It’s fair to say that black holes may be the scariest objects in the universe. Happily for us, the nearest is probably many light-years away. Unless of course, Planck relics are a thing - in which case they might be literally everywhere.

What is inside a black hole? Inevitable crushing doom? Gateways to other universes? Weird, multidimensional libraries? If you’ve ever wanted to know then you might be in luck - Some physicists have argued that you’re inside one right now.

When physicists talk about black holes they’re usually referring to highly theoretical objects – static, unchanging black holes viewed from “infinitely” far away. This makes everything clean and simple enough to attempt the already...

Niels Bohr, a Danish Physicist said “Everything we call real is made of things that cannot be regarded .” Is what we see perceived to be real or is it an illusion?

In the world of our mind’s eye, light travels in a straight line....

Sometimes our mathematical hacks point to strange new aspects of reality. For example Max Planck used a quantization trick to figure out the spectrum of light emitted by hot objects. The quantization part of his math trick was meant to...

So, how do you take a picture of a black hole? The beast in question is the supermassive black hole in the center of this – the M87 elliptical galaxy. It has an estimated mass of several billion times that of the Sun, which gives it an...

Black holes are about the worst subjects for direct study in the universe. But at this stage, it’s all we can do to convince ourselves of their existence. Actually studying the physics of real black holes is much, much harder. I mean, we...

Have you ever asked “what is beyond the edge of the universe?” And have you ever been told that an infinite universe that has no edge? You were told wrong. In a sense. We can define a boundary to an infinite universe, at least...

This is a map of the multiverse. Or in physics-ese, it’s the maximally extended Penrose diagram of a Kerr spacetime. And in english: when you solve Einstein’s equations of general relativity for a rotating black hole, the universe does...

Black holes are a paradox. They are paradoxical because they simultaneously must exist but can’t, and so they break physics as we know it. Many physicists will tell you that the best way to fix broken physics is with string. String...