What a great way to start the week: the Foundational Questions Institute has just announced its fifth essay contest. The topic is the physics of information. It could hardly be more timely, and not just because of the cultural Zeitgeist. Going to a physics conference these days is like landing in The Village of the [...]

The first time I ever saw quantum entanglement for myself was in August 2011 on a road trip to Colgate University. Goodness knows how many blog posts and magazine articles have been written about the quantum realm, invariably describing it as weird. But I’d never actually seen this supposed mind-blowingness with my own eyes, which [...]

For physicists trying to make sense of quantum mechanics, Albert Einstein’s thinking remains highly relevant. “This guy saw more deeply and more quickly into the problems that plague us today,” one quantum physicist told me. The latest volume of the Collected Papers of Albert Einstein, which contains Einstein’s publications, draft papers, letters, and scribblings from [...]

In my last post, I scrounged the parts for a very crude, but very cool, experiment you can do in your basement to demonstrate quantum entanglement. To my knowledge, it’s the cheapest and simplest such experiment ever done. It doesn’t give publishable results, but, to appropriate a line from Samuel Johnson, a homebrew entanglement experiment [...]

Quantum entanglement experiments are not something you can buy in the science kit aisle at Toys ’R Us. The cheapest kit I know of is a marvel of miniaturization, but still costs 20,000 euros. In the past month, though, I’ve put together a crude version for just a few hundred dollars. It’s unbelievably simple—so simple [...]

The whole point of an explanation is to reduce something you don’t know to something you do. By that standard, you don’t gain much by explaining anything in terms of black holes. Appealing to the most mysterious objects known to science as an explanation sounds like using one mystery to explain another. Yet this is [...]

In chatting with colleagues after a talk this week, Joe Polchinski said he’d love to fall into a black hole. Most theoretical physicists would. It’s not because they have some peculiar death wish or because science funding prospects are so dark these days. They are just insanely curious about what would happen. Black holes are [...]

For years I’ve been thinking and hoping that quantum physics would become the next hacker revolution. DIYers in their basements, garages, and hackerspaces have already pioneered radio communications, PCs, household robots, and cheap 3-D printers—why not quantum entanglement, cryptography, computers, and teleportation? In recent years, physics educators have streamlined quantum experiments to the point where [...]

In about 10 minutes, using stuff you probably already have lying around your house, you can watch atomic nuclei and elementary particles for yourself using a diffusion cloud chamber—a rudimentary particle detector. There are lots of websites and YouTube videos giving step-by-step instructions to build such a chamber, but all require some component that’s hard [...]

It may well have been the liveliest hour and a half I’ve ever spent in the company of theoretical physicists. In April, during a workshop I was attending on black holes, Bill Unruh gave a talk that challenged his colleagues on a point almost all of them thought had been settled in the mid-1980s. His [...]

I’m a believer in wishful thinking, in the power of our hopes to become self-fulfilling. I even believe that war is going to end! But at some point, if wishful thinking diverges too sharply from what we can reasonably expect from reality, it morphs into denial or delusion. David Deutsch’s hope that science will keep [...]

Two teams of researchers have extended the reach of quantum teleportation to unprecedented lengths, roughly equivalent to the distance between New York City and Philadelphia. But don’t expect teleportation stations to replace airports or train terminals—the teleportation scheme shifts only the quantum state of a single photon. And although part of the transfer happens instantaneously, [...]

There’s something unnerving about unifying physics. The two theories that need to be unified, quantum field theory and Einstein’s general theory of relativity, are both highly successful. Both make predictions good to as many decimal places as experimentalists can manage. Both are grounded in compelling principles. Both do have flaws — including an unfortunate tendency to [...]

SANTA BARBARA—”Maybe we’re just too dumb,” Nobel laureate physicist David Gross mused in a lecture at Caltech two weeks ago. When someone of his level wonders whether the unification of physics will always be beyond mortal minds, it gets you worried. (He went on to explain why he doesn’t think we are too dumb, though.) [...]

PASADENA—The theory is so obscure there’s not a Wikipedia page about it yet. It might be impossible to formulate mathematically. One theoretical physicist calls it the Emperor Palpatine of theories, even more powerful and inscrutable than the Darth Vader theory that he and others have been studying intensively. And yet it has a purity and [...]

Conventional wisdom has it that putting the words “quantum gravity” and “experiment” in the same sentence is like bringing matter into contact with antimatter. All you get is a big explosion; the two just don’t go together. The distinctively quantum features of gravity only show up in extreme settings such as the belly of a [...]

Simply put, bottomlessly deep: that is the definition of a great discovery in science. From the principle of relativity to evolution by natural selection, the concepts that govern our world are actually not that hard to state. What they mean and what they imply—well, that’s another matter. And so it is with quantum entanglement. One [...]

Just when you thought you’d heard every quantum mystery that was possible, out pops another one. Jeff Tollaksen mentioned it in passing during his talk at the recent Foundation Questions Institute conference. Probably Tollaksen assumed we’d all heard it before. After all, his graduate advisor, Yakir Aharonov—who has made an illustrious career of poking the [...]

The late philosopher Robert Nozick, talking about the deep question of why there is something rather than nothing, quipped: “Someone who proposes a non-strange answer shows he didn’t understand the question.” So, when Scott Aaronson began a talk three weeks ago by saying it would be “the looniest talk I’ve ever given,” it was a [...]

Light makes for a terrific carrier of information—witness the prevalence of fiber optics in telecommunications—and the realm of quantum communication is no different. Photons are key quantum objects that can carry information over large distances and that can be entangled in relatively large numbers. But photons are a hyperactive lot, zipping around at light speed, [...]