Galaxy Simulations Offer a New Solution to the Fermi Paradox

As far as anyone knows, we have always been alone. It’s just us on this pale blue dot, “home to everyone you love, everyone you know, everyone you ever heard of,” as Carl Sagan so memorably put it. No one has called or dropped by. And yet the universe is filled with stars, nearly all those stars have planets, and some of those planets are surely livable. So where is everybody?

The Italian physicist Enrico Fermi was purportedly the first to pose this question, in 1950, and scientists have offered a bounty of solutions for his eponymous paradox since. One of the most famous came from Sagan himself, with William Newman, who postulated in a 1981 paper that we just need patience. Nobody has visited because … Read the rest

Neuroscience Readies for a Showdown Over Consciousness Ideas

Some problems in science are so hard, we don’t really know what meaningful questions to ask about them — or whether they are even truly solvable by science. Consciousness is one of those: Some researchers think it is an illusion; others say it pervades everything. Some hope to see it reduced to the underlying biology of neurons firing; others say that it is an irreducibly holistic phenomenon.

The question of what kinds of physical systems are conscious “is one of the deepest, most fascinating problems in all of science,” wrote the computer scientist Scott Aaronson of the University of Texas at Austin. “I don’t know of any philosophical reason why should be inherently unsolvable” — but “humans seem nowhere close to solving it.”

Now a new … Read the rest

The Universe’s Ultimate Complexity Revealed by Simple Quantum Games

One of the biggest and most basic questions in physics involves the number of ways to configure the matter in the universe. If you took all that matter and rearranged it, then rearranged it again, then rearranged it again, would you ever exhaust the possible configurations, or could you go on reconfiguring forever?

Physicists don’t know, but in the absence of certain knowledge, they make assumptions. And those assumptions differ depending on the area of physics they happen to be in. In one area they assume the number of configurations is finite. In another they assume it’s infinite. For now, at least, there’s no way to tell who’s right.

But over the last couple years, a select group of mathematicians and computer scientists has been busy … Read the rest