Spooky influences might leap not just across space, but across time, too.
The mysteries of quantum mechanics are usually portrayed as mysteries of space: how strange that the fates of particles on opposite sides of the universe could be joined. But they are also mysteries of time. A particle you create today could be connected in some unaccountable way to one that does not exist yet. Einstein […]
Entanglement is not the only type of nonlocality in quantum theory.
It stands to reason that electromagnetism is a theory of electric and magnetic fields. But since when is anything in physics so straightforward? Although Maxwell’s equations of electromagnetism in their usual formulation do contain electric and magnetic fields, those equations can be rewritten in terms of a mathematical function called the potential. So what is […]
The atoms of space may be tiny, but could have huge effects.
If spacetime is made of atoms, as many theoretical physicists these days speculate, could we ever know? You might doubt it. Conventional wisdom says those atoms would be too small, too energetic, or just plain too weird. But Daniele Oriti thinks we have a shot. Oriti, an Italian theorist working at the Max Planck Institute […]
Short answer: It’s largely a self-reinforcing expectation.
Every area of journalism presents its challenges, but quantum physics is in a molecular orbital of its own. It demands more time per word than anything else I’ve written about. Why is that? Earlier this month I offered some thoughts to fellow science journalists attending a philosophy-of-physics workshop at the University of Leeds. Although my […]
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 […]
To test the interpretation of quantum mechanics, look to cosmology.
Quantum physicists do love their beer. By day they build instruments, measure numbers, solve equations. By night they retire to the bar or pub and muse about the philosophical puzzles of quantum theory. By “philosophical” they mean “fun but impractical.” Maybe quantum theory betrays the existence of parallel universes, maybe it exposes causal influences coming […]
When physicists get stuck, call in the philosophers.
The nice thing about philosophers of physics is that they have no dog in the fight among string theory, loop quantum gravity, and other competing approaches to a fundamental theory of nature. They can stand back and offer some third-party perspective. One who specializes in this is Karen Crowther, a postdoc in the University of […]
Thumb your noise at government surveillance with a highly simplified form of quantum cryptography.
“Are you telling me that this could be of practical use?” exclaimed the Irish physicist John Bell. He had shown in the 1960s that quantum entanglement burrowed deep into the foundations of physics, but even he hadn’t thought it could have real-world applications. That was the brainstorm of Artur Ekert, then a graduate student at […]
Here’s a talk I gave at the Centre for Quantum Technologies in Singapore on March 24, 2016. Note that it was the first time I’d given this particular talk and it had a couple of first-iteration glitches.
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 […]
The debate over quantum nonlocality awaits its resolution in a unified theory of physics.
If anyone is the Kissinger of quantum physics—in a good way, striving to forge peace in the century-old dispute over the meaning of the quantum—it is Howard Wiseman. A theoretical physicist at Griffith University in Brisbane, Australia, Wiseman thinks the debate hasn’t been resolved because it can’t be, given our present state of knowledge. Only […]
“Atoms” of space are too small to see, but betray themselves indirectly.
I’m fascinated by how the humblest observations can lead you to the profoundest conclusions, and here’s one I learned from Thanu Padmanabhan, an eminent theoretical physicist at the Inter-University Centre for Astronomy and Astrophysics in Pune, India. Suppose you cup your hands around a glass of cold water to warm it up. From this simple […]
The eminent Israeli physicist explains the peculiar type of action at a distance that bears his name.
In 1959 physicists Yakir Aharonov and David Bohm startled their colleagues by predicting a new type of quantum nonlocality, distinct from the phenomenon that had spooked Einstein. They showed that an electric or magnetic field can have an effect on a particle at a distance: even when the field exerts no force on that particle, […]
How quantum correlations transcend space and time.
The great mystery of quantum mechanics is that particles can be connected without a connector. They can coordinate their behavior in ways that are too complicated to be preprogrammed into them, even though no process is acting across the distance between them. “We can’t say that one thing led to another,” Nicolas Gisin of the […]
A simple model of the phase transition that begat space.
Could space as we know it be just one possible phase of the universe, able to undergo a transition to or from an entirely alien structure? This video animation shows how that might happen, according to a model known as quantum graphity, developed by theoretical physicists Tomasz Konopka, Fotini Markopoulou, Lee Smolin, and others. (The […]
Einstein's underappreciated argument for the strangeness of quantum physics.
“This onslaught came down on us as a bolt from the blue,” recalled Léon Rosenfeld, a young colleague of the physicist Niels Bohr. They were shocked, shocked, by Einstein’s famous 1935 critique of their interpretation of quantum mechanics. But why the surprise? Einstein’s argument did not originate in 1935 or even with his storied confrontation […]
By thinking of nature as a hierarchy, scientists dissolve the dichotomies they have wrestled with.
Is the universe deterministic or indeterministic? A clockwork or a craps table? In this month’s issue of Scientific American, I have an essay arguing that the answer is: both. The world can be deterministic on some levels and indeterministic on others; these two categories are not mutually exclusive. To me, this is the essence of […]
A leading theorist explains quantum entanglement and what it might mean for the structure of spacetime.
Some of the most interesting conversations I’ve had in my life have been with Ted Jacobson, a theoretical physicist at the University of Maryland. A musician, an amateur baker, and co-creator of loop quantum gravity, he is deeply self-reflective—a man who always questions his own thinking, who used to criticize string theory but then came […]
Spacetime seems to have a granular structure, but what the heck are the grains?
Joe Polchinski, based at the Kavli Institute for Theoretical Physics in Santa Barbara, is one of the world’s leading string theorists and an avid cyclist. (Many colleagues have challenged him to a race, to their later chagrin.) He is best known for showing that string theory isn’t just about strings—it predicts a huge diversity of […]
Spacetime derives from a deeper quantum reality, suggests the U.C. Santa Barbara theoretical physicist.
One of the scientists I follow in my book is Steve Giddings, a theoretical physicist at U.C. Santa Barbara who is also a highly skilled mountain-climber. In this video, he explains how quantum mechanics, when applied to black holes, calls the principle of locality into question and suggests that spacetime is not a fundamental ingredient […]
David Bohm's longtime collaborator explains why he thinks quantum physics describes a holistic reality.
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 […]
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 […]
Four times the circumference, seven times as much energy: Is that really what it’ll take to test multiverse theories?
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 […]
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 […]
The cheapest and easiest way to do the famous Einstein-Podolsky-Rosen experiment.
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 […]
The cheapest and easiest way to do the famous Einstein-Podolsky-Rosen 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 […]
Who’d have thought viscous fluids would act like gravitational waves caroming off a black hole?
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 […]