# What are Gravitons and Why Can't We See Them?

Gravitons are tiny particles that carry the "force" of gravity. They are what brings you back down to Earth when you jump. So why have we never seen them, and why are they so impossibly complicated we need string theory to figure them out? Find out here!

# How ​Music Proves We Live In Three Dimensions

String theory has dimensions popping up all over the place. We are currently at over 10 dimensions. But how would living in that many dimensions affect us? The first thing to do would be to throw out all your albums, because they won't sound right anymore.

# What the Hell Are Tachyons?

Tachyons cause a lot of problems in movies with starships, but they also cause problems for people in real life. Specifically, they cause problems for students of relativity and string theorists. Learn about the ins and outs of tachyons, and why they need extra dimensions.

# Brian Greene explains string theory to us in just 14 words

Theoretical physicist Brian Greene joined us for a Q&A today where he answered several of our most burning questions about string theory, starting with the most basic: Just what is string theory anyway?

# 10am-11am PST: Brian Greene Q&A on string theory

Renowned physicist Brian Greene is here to answer all your questions about theoretical physics, superstring theory, and his new online science education website, World Science U, launching today.

# Scientists May Have Finally Found a Practical Test for String Theory

String theory a beautiful, elegant piece of science which claims to unify all the forces in the Universe by representing tiny point-like particles as one-dimensional vibrating strings. It's as clever as it is wacky but is—conveniently—untestable. Until, perhaps, now.

Question: What do you get when you mix a cappella, sock puppets, string theory and Queen? Answer: The geekiest (and astonishingly good, musically speaking) cover of "Bohemian Rhapsody" EVAR. Easily the greatest physics-themed cover of the classic we've ever heard. Seriously. The thing's a masterpiece.

# Does infinity really exist?

Our universe appears to be bound by a finite set of laws, yet we often talk about things that go on for an eternity. "Infinity" is a strange idea. But it's crucial if you want to understand anything from philosophy to mathematics. Here’s why.

# Humanity Will Never Be Overrun By Spontaneously Forming Space Brains

Good news, everyone! A new interpretation of string theory is proposing that Boltzmann Brains — those disembodied brains that could emerge spontaneously in outer space — will never outnumber humans.

# Must Watch: Neil deGrasse Tyson Moderates a Debate on Nothingness

For 14 years now, the American Museum of Natural History has hosted the Isaac Asimov Memorial Debate – an annual meeting of scientific and philosophical minds, held in honor of one of modern history's most formidable intellects. The debates are always fantastic, but this year's topic – the existence of nothing –…

# How Do You Count Parallel Universes?

Cosmologists have been thinking for years that our universe might be just one bubble amid countless bubbles floating in a formless void. And when they say "countless," they really mean it. Those universes are damned hard to count.

# Why Physicists Need Philosophers

There's a spat brewing between some theoretical physicists and philosophers of science recently, and NPR's Adam Frank has all the details. It started when one philosopher of science, David Albert, questioned the notion that the universe came "from nothing," as the title of Laurence Krauss' new book claims. This…

# The Trouble With String Theory

Particle physics is to physics what big game hunting is to field biology. While theoretical physicists pore over their mathematical models, particle physicists are out in the brush with their pith helmets and shotguns, speaking softly, carrying big accelerators and blowing stuff up real good.

# Faster-than-light neutrinos could be proof of extra dimensions

The recent announcement that neutrinos had been observed seemingly going faster than the speed of light sent shockwaves through the physics community. But there's one possible explanation that could keep Einstein's relativity intact and open up a whole new cosmos.

# The universe probably isn't a giant hologram after all

One of the strangest and most exotic theories to come out of theoretical physics is that the entire universe is a projection of a two-dimensional shell. But the latest evidence suggests the cosmic hologram really is just a crazy theory.

# Five weird theories of what lies outside the universe

Physicists have long studied the nature of the universe. But some go a step further into the unknown (and probably unknowable), contemplating what lies outside the boundaries of our universe.

# How the Large Hadron Collider could create time-travelling Higgs particles

A crucial goal for the Large Hadron Collider is to find the long-sought Higgs boson. It might also create another Higgs particle that only travels through hidden dimensions, meaning it can pop in and out of any point in time.

# String theory fails first major experimental test

String theory is one of the more popular candidates to combine quantum mechanics and relativity into a grand unified theory. But it had remained completely untestable until recent experiments at the Large Hadron Collider. The early results don't look good.