It’s not usually put like this, but the discovery of primordial gravitational waves two weeks ago has given us our first direct glimpse of a period before the big bang. [The discovery was later retracted, but I’ll keep this post here to show why theorists at the time found it so exciting.] The term “big […]

A couple of weeks ago, I was writing up a description of Einstein’s general theory of relativity, and I thought I’d compare the warping of spacetime to the motion of Earth’s tectonic plates. Nothing on Earth’s surface has fixed coordinates, because the surface is ever-shifting. Same goes for spacetime. But then it struck me: if […]

VIENNA—One night in 1952, Richard Feynman and David Bohm went bar-hopping in Belo Horizonte. Louisa Gilder reconstructs the night in her brilliant book on the history of quantum mechanics, The Age of Entanglement. Feynman was on a sabbatical in Rio and, ever exuberant, raved about local beers, drumming lessons, and Brazilian girls. Bohm, teaching at […]

VIENNA—Over the past several days, I attended a fascinating conference that explored an old idea of Einstein’s, one that was largely dismissed for decades: that quantum mechanics is not the root level of reality, but merely a hazy glimpse of something even deeper. A leading advocate is Gerard ’t Hooft of Utrecht University, who shared […]

The Large Hadron Collider has only just begun its explorations, so it might seem a little premature to begin thinking about what new particle projects might come next. But given how long these things take to plan, is it ever too soon? This summer, particle physicists held a huge planning retreat in Minneapolis, which Peter […]

Could time come to an end? What would that even mean? In April 2013 I gave a talk about this strange physics idea at a TEDx event in Trento, Italy, based on a Scientific American article I wrote in 2010. My conceit was that time’s end poses a paradox that might be resolved if time […]

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 […]

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 exactly 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 […]

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. Angels on a pin are nothing to this. There’s no unambiguous way to count items in an […]

SANTA BARBARA—Someone once asked me to describe string theory in 26 seconds, so, a couple of months ago, I went down to Goleta Beach with my iPhone and recorded this little video. It’s kind of spacey, I admit. Soundtrack and dog were entirely unintentional.

Last Thursday, my colleague John Matson described a truly amazing galaxy known, somewhat unromantically, as BX442. It has a majestic spiral pattern while hundreds of its galactic contemporaries were gawky and misshapen—a peculiar and special anomaly which suggests to many astronomers that cosmic pinwheels are ephemeral art forms, like Tibetan sand mandalas. John’s piece spurs […]

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 […]

SINGAPORE—I’d heard of quantum dice, quantum poker, quantum roulette, and even quantum Russian roulette, but a quantum horse race? I learned about this surreal game of chance last December during a symposium at the Centre for Quantum Technologies in Singapore. Start with a row of rubidium atoms, place your bets, let ʼem go, and measure […]

At a lecture I went to some years ago, astrophysicist Trevor Weekes compared garden-variety elementary particles to mosquitoes. They are plentiful and easy to find—indeed, they find you. But ultra-high-energy gamma rays, he said, are like elephants. They are fairly rare, but among the greatest of creatures. They often roam in spectacular habitats. Their sheer […]

SANTA BARBARA—Two years ago several of my Sci Am colleagues and I had an intense email exchange over a period of weeks, trying to figure out what to make of a new paper by string theorist Erik Verlinde. I don’t think I’ve ever been so flummoxed by physicists’ reactions to a paper. Mathematically it could […]

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—Physics has always been one of the most globalized of professions. Physicists think of themselves as supranational, rising above national and cultural concerns. They may not always live up to this ideal, but at least they try. I got a glimpse of this as a college student in 1987 when I spent my spring […]

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 […]

Here’s the sort of crazy idea that animates our office conversation at Scientific American. It all started with my colleague Michael Moyer’s joke that a certain politician could build his moon base using a balloon: just capture the hot air and float all the way up. Ha ha, we all know that balloons don’t work […]

AUSTIN, Texas—Astrophysicists have a funny attitude toward magnetic fields. You might say they feel both repelled and attracted. Gravitation is assumed to rule the cosmos, so models typically neglect magnetism, which for most researchers is just as well, because the theory of magnetism has a forbidding reputation. The basic equations are simple enough, solving them […]