If You Think Quantum Physics Is Weird, Try These Theories

As strange as quantum entanglement is, the world would have been even stranger without it.

It’s quite a trick to picture a theory even weirder than quantum mechanics. Yet many physicists think the best way to make sense of quantum mechanics is to imagine what might have been. Within a vast radiation of conceivable theories, they look for principles that single out the quantum. In so doing, they aim to […]

FAQ: How Are Entangled Particles Created? [Video]

Shine a laser on a nonlinear optical crystal to get streams of entangled photons.

The number-one question that people ask me when I talk about nonlocality is: how are entangled particles created? I didn’t say much about this in the first edition of my book because the details don’t matter for my overall argument, but since everyone wants to know, I figure I should elaborate. (I’ve also added an […]

A Hologram Shows How Space Could Pop Into Existence

The holographic principle—with a real hologram

I remember buying my first hologram as a college student in the mid-1980s. It showed a bed of nails. I came across it at a gallery in what was then the world’s capital of spacey trinkets, Haight Street in San Francisco. When I picked it up, the hologram looked like a featureless sheet of film, […]

Does Some Deeper Level of Physics Underlie Quantum Mechanics? An Interview with Nobelist Gerard ’t Hooft

Is the notorious randomness of quantum mechanics just a front?

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 […]

George and John's Excellent Adventures in Quantum Entanglement, Part 2 [Video]

Here’s what an entanglement experiment actually looks like.

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 […]

When You Fall into a Black Hole, How Long Have You Got?

Maybe not long at all, if black holes are ringed by “firewalls.”

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 […]

How Do You Count Parallel Universes? You Can't Just Go 1, 2, 3, ...

Introducing a whole new breed of number, the p-adics.

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 […]

Does It Matter If Black Holes Are Popping into Existence Around Us All the Time?

Black holes are not just distant cosmic monsters. Microscopic ones may exist all around us, with potentially momentous consequences.

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 […]

Quantum Horse Races and Crystals of Light

Start with a row of rubidium atoms, place your bets, let ’em go.

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 […]

Is Dark Matter a Glimpse of a Deeper Level of Reality?

Many theoretical physicists speculate that space and time arise from deeper physics. Erik Verlinde goes them one further.

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 […]

Where Do Space and Time Come From? New Theory Offers Answers, If Only Physicists Can Figure It Out

Vasiliev theory might extend string-theoretic ideas to new settings. But dang, is it hard.

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.) […]

The Emperor, Darth Vader and the Ultimate Ultimate Theory of Physics

This physics theory is like Darth Vader: you think it’s the ultimate power, until you meet the Emperor.

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 […]

Could Simple Experiments Reveal the Quantum Nature of Spacetime?

Gravity might muck with the quantum by distorting the uncertainty principle and introducing ambiguities in sequences of cause and effect.

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 […]

George and John's Excellent Adventures in Quantum Entanglement [Video]

A metaphorical version of John Bell’s famous entanglement.

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 […]

Proving You Are Where You Say You Are

Philandering spouses and students playing hookey, beware: quantum cryptography may make it impossible for you to hide your location.

SINGAPORE—When a speaker brings a tangle of garden hoses, a bottle of water, and a towel to the podium, you know it’s going to be a fun talk. Computer scientist Harry Buhrman of the Centrum Wiksunde & Informatica in Amsterdam recently visited Singapore to help celebrate the fourth anniversary of the Centre for Quantum Technologies. […]

Quantum Cheshire Cat: Even Weirder Than Schrödinger's

A box can contain all the properties of a particle, even though no particle is there.

COPENHAGEN—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 […]

Free Will and Quantum Clones: How Your Choices Today Affect the Universe at its Origin

Just when you thought the debates over free will couldn’t get any weirder.

COPENHAGEN—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 […]

Deep in Thought: What Is a “Law of Physics,” Anyway?

Physicists and philosophers struggle with the most basic of questions.

WATERLOO, Ontario—One thing that’s both disconcerting and exhilarating about physics is how many seemingly simple questions remain unanswered. When you hear the questions that physicists struggle with, you sometimes say to yourself, Wait, you mean they don’t even know that? Physics might be defined as the subject that tries to figure out why the world […]

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