Imagine that you want to make something disappear—that unfortunate photograph of you in the sombrero, or the ill-advised iPhone video from your bachelor party, or that part of your seventh-grade diary describing your dream honeymoon with Kirk Cameron. Whatever it is, you want it gone.
You could shred it, but a motivated blackmailer could still piece it back together. You could burn it, but the laws of physics still promise that the information could be reassembled. So you decide to turn to the ultimate destruction: You launch that mortifying evidence right into a black hole and breathe a sigh of relief that now, finally, it is gone for good.
But is it really?
That question is at the heart of a problem that’s been called the black hole information paradox, and some theorists believe that it reveals a deep crack in the foundation of physics as we know it.
The pull of gravity inside a black hole is so strong that nothing can escape its grip. No one can fish your diary out from beyond the lip of the black hole; gravity’s pull on the fishing line would overpower your reel every time. And if a tech-savvy enemy tried to remotely link up with your iPhone and retrieve that embarrassing video, even the electromagnetic waves from your phone would still be trapped inside the black hole. To escape, they would somehow have to travel faster than the speed of light—and that is strictly forbidden by Einstein’s relativity.
But there is a hitch. Quantum mechanics has an equally strong rule that prohibits the loss of information. This principle, called unitarity, is intimately linked with other unbreakable laws of physics, like conservation of energy. “Conservation of information is what holds the world together,” says Steve Giddings, a physicist at the University of California, Santa Barbara.
To emphasize just how important information conservation is, Stanford physicist Leonard Susskind calls it the “minus-first” law of physics—“minus-first because I think it comes before everything else,” said Susskind in an online discussion sponsored by the Kavli Foundation. “If it’s true [that information conservation is violated], we go back to minus-first base.”
Now, you might argue that the information in the black hole isn’t truly lost. It’s just locked up and inaccessible. Theorists contented themselves with this view until 1975, when Stephen Hawking drew a revolutionary conclusion about black holes: Given enough time, a black hole will dematerialize, radiating away through a process we now call Hawking evaporation. And, according to Hawking’s accounting, that radiation would be random, revealing nothing of the black hole’s contents.
As Leonard Susskind wrote in “The Black Hole War,” his 2008 book on the problem of black holes and information loss, “The possibility of hiding information in a vault would hardly be a cause for alarm, but what if when the door was shut, the vault evaporated right in front of your eyes? That’s exactly what Hawking predicted would happen to the black hole.”
There is another possibility, though: Maybe this evaporation isn’t complete. Maybe it leaves behind a tiny ember that contains an enormously compressed version of all the information that ever fell into the black hole. “But this leads to some pretty crazy conclusions, too” says Giddings—specifically, you need to find a way for a single particle to take on infinitely many forms which, Giddings says, “results in equally disastrous consequences.”
This left physicists stuck between a rock and a hard place: Either information could be lost, or somehow something could escape from a black hole. A central tenet of quantum mechanics was pitted against the cornerstone of relativity. One theory, it seemed, had to give.
The debate went public in 1997, when Stephen Hawking and theoretical physicist Kip Thorne made a bet with John Preskill of Caltech that it would ultimately be shown that information was truly lost inside black holes. At stake: one encyclopedia of the winner’s choice, from “which information can be recovered at will.”
At the same time, and out of the media spotlight, string theorists were exploring a remarkable duality in their equations. They found that if you take a mathematical description of a system and add an extra spatial dimension and a negative curvature, you have something that looks very much like quantum fields in a three-dimensional universe without gravity. This observation sounds esoteric, but it gave mathematical chops to an idea called the holographic principle, which puts forward that all the information in our three (spatial) dimensional universe can be “stored” on a two-dimensional surface. In the context of the black hole information paradox, this suggested that information about the stuff in the black hole could somehow be encoded on the surface of the event horizon.
Still, the encyclopedia remained unclaimed as the bet dragged on, until 2004, when Hawking announced that he had changed his mind and was ready to concede. (Preskill’s prize: a baseball encyclopedia.) “My views have evolved,” he told Nature News. He published his results the following year.
To some theorists, Hawking’s concession came many years too late. “Stephen Hawking was like one of those unfortunate soldiers who wander in the jungle for years, not knowing that the hostilities have ended,” wrote Susskind in “The Black Hole War.” But others found Hawking’s explanation unsatisfying and, moreover, were irked at the public perception that one man’s change of heart had truly settled a debate that was still actively raging in the physics community. Still, there was a growing, if uneasy, consensus that this mathematical expression of the holographic principle, dubbed the anti-de Sitter/conformal field theory, or AdS/CFT, duality, pointed the way to a solution to the information problem, even if the roadmap was incomplete.
But now, we’ve hit another roadblock. A team of physicists out of the University of California, Santa Barbara has shown that if information thrown into the black hole is conserved, one of two other “unbreakable” rules of physics must give out. The first rule is that, once you’re a reasonable distance away from a black hole, the laws of physics work as usual. The second is that someone falling into a black hole would experience nothing “special” at the event horizon.
It’s that second rule, the Santa Barbara team argues, that is the weakest link in the chain. To protect the remaining postulate, they are willing to accept that something shocking might exist at the horizon: a “firewall” of broiling radiation that burns all that passes into a fiery crisp. Do they really believe that these firewalls exist? Probably not. But the possibility is enough to light a new fire (pardon the pun) under theorists.
Paradoxes and problems, after all, can drive great new discoveries. And, as science writer Jennifer Ouelette writes, “It comes at a time when theorists are hungry for a new challenge,” thanks to the maddening neatness of the Higgs result and physicists’ inability to spot cracks in the armor of the Standard Model.
So, back to that embarrassing thing you wanted to dump into the nearest black hole. Will it really be lost and gone forever? Will it burn up in a firewall, or be rewritten on a quantum screen at the edge of the universe? With the jury still out, perhaps you’ll do better just to hide it under the mattress.
Author's picks for further reading
arXiv: Black Holes: Complementarity or Firewalls?
The 2012 paper that laid out the firewall problem.
Cosmic Variance: Joe Polchinski on Black Holes, Complementarity, and Firewalls
Go inside the information paradox with physicist Joe Polchinski, one of the authors of the paper that sparked the firewall controversy.
John Preskill: On Hawking’s Concession
The winner of the famous bet on the information problem and the value of scientific wagers.
Physics Today: Black holes, quantum information, and the foundations of physics
In this comprehensive essay, Steve Giddings outlines the information problem and several proposed solutions.
Albert Einstein during a lecture in Vienna in 1921, the year of his Nobel Prize. Image credit: Ferdinand Schmutzer, via Wikimedia
It's 5 a.m. and you're sitting by the phone, hoping for that "magic call" from Stockholm that bears the news you've waited so long for: You've won the Nobel Prize in Physics! Whom will you tell first? How will you celebrate? And what color Bugatti should you buy with your prize money?1 But while you're mentally debating the relative merits of Obsidian Black and Italian Red, you realize that the sun has come up and the phone still sits silent: You've been passed over once again. How can you turn things around in 2013? With the announcement of the 2013 Nobel Prize in Physics expected to come on Tuesday, October 8, we consulted with winners and watchers of the Nobel Prize to prepare this helpful guide to nabbing your very own physics Nobel.
- Think big: What kind of discovery is most likely to earn Nobel laurels? Prize-winning work "runs the gamut" from basic to applied science and from lone-wolf labor to cast-of-thousands collaborations, says Adam Riess, who, along with Saul Perlmutter and Brian Schmidt, received the award in 2011 for the discovery of the accelerating expansion of the universe. Says Riess: "I think the key is its importance must be fundamental, generally involving new physics."
- Do an experiment: Physicists are often divided into two camps: theorists, who need nothing more than paper, pencil, and their prodigious brains to do their work, and experimentalists, who toil and tinker with arcane equipment in their attempts to prove (or disprove) the ideas thought up by the theorists. So, which group bags more Nobels? In The Nobel Prize: A History of Genius, Controversy, and Prestige, science historian Burton Feldman lands firmly on the side of experiment. Tallying up the winners from 1901 through 1999, he finds that experimentalists scooped up 87 awards while the theorists made do with a measly 51. Even Einstein, despite a bushel of nominations, was rejected year after year for the Nobel because his relativity theories were just that—theories. (He eventually won the 1921 prize, for his work on the photoelectric effect.) Experimentalists have continued to dominate in the last decade, with a few notable exceptions, like the 2004 award, which went to David Gross, David Politzer and Frank Wilczek for developments in the theory of the strong force, one of the fundamental forces of physics.
- Keep it in the family: Marie Curie shared the prize with her husband, Pierre Curie, and five father-son pairs have won the award (though only William and Lawrence Bragg won it in the same year for work done collaboratively). As David Kaiser, a physicist and science historian at MIT, puts it: To win the award, "one should select one's parents carefully."
- You can’t choose your family, but you can choose your thesis advisor: “As the great sociologist of science Harriet Zuckerman demonstrated years ago, among all the Nobel laureates who conducted their prize-winning research in the United States (at least up through 1972), more than half had been mentored early in their careers by other Nobel laureates,” reports Kaiser. “The proportion was highest—nearly 2/3—among Nobel Prize-winners in physics.”
- Be a man—and be eligible for the AARP: Of the 193 winners of the Nobel Prize in Physics, only two (Marie Curie and Maria Goeppert-Mayer) were female. Average age: 55.
- Get lucky: “They key to winning the Prize, I believe, is to be extremely lucky,” says Riess. Of course, as any fortune cookie can tell you, good luck alone isn’t enough: it has to be combined with the day-in, day-out hard work that often obscures the serendipitous path to the breakthrough. But it is possible to “court serendipity” by being open to surprising and unexpected new findings. The Institute of Physics has compiled a list of just such lucky breaks. There’s Jocelyn Bell’s “accidental” discovery of pulsars—radio signals so uncannily regular that she momentarily thought they might be beacons from an alien civilization. (They weren’t. Incidentally, Bell didn’t get the prize; it went to her supervisor, Anthony Hewish. See #5, above.) And then there’s the first detection of the radio buzz we now know as the cosmic microwave background radiation, which future Nobel laureates Arno Penzias and Robert Wilson chalked up to pigeon droppings before they realized it was actually an electromagnetic echo of the Big Bang.
- Be patient: The Nobel committee is not much for instant gratification. Though some Nobel prizes come quick on the heels of the work that they honor—the 2010 award, for instance, went to Andre Geim and Konstantin Novoselov for their work on graphene, just six years after the material was discovered—the prize more often comes a decade or two (or five) after the discoveries are first made. Subramanyan Chandrasekhar, for one, had to wait more than 40 years, and 53 years passed before Ernst Ruska was honored for building the first electron microscope that could out-magnify a traditional optical scope.
- Be prepared for life after Nobel: “What happens now to the rest of my life? What comes after this?” said Tsung-Dao Lee, who received the physics prize in 1957, when he was just 31. Indeed, some laureates, particularly those who receive the award early in their careers, founder after making the trip to Stockholm. As Mitchell Wilson put it in a 1969 essay in The Atlantic, "If, before winning the prize, the man has received very few, if any, of the signs of the scientific world’s recognition of the worth of his work, the sudden rise to stardom can completely distort the pattern of the rest of his life." But Nobel laureate Frank Wilczek, asked to weigh in on how to up your Nobel odds, has a more spirited outlook: "I'm more confident giving this tip, about what to do immediately after winning a Nobel Prize. And that is, you should take some dancing lessons. They'll pay off handsomely during the festivities."
1Just kidding; I'm not aware of any Nobel laureates who plunked down their prize money on a supercar. Nobel winners typically spend the purse on serious and practical things, like charitable donations or their children's college fund. TIME put this impolite question to a handful of winners back in 2009; here are their answers.
Author's suggestions for further reading
The Atlantic: How Nobel Prizewinners Get That Way
In this 1969 essay, physicist-turned-novelist Mitchell Wilson profiles prominent winners of the physics Nobel, including his onetime boss, laureate Enrico Fermi.
The Nobel Prize: A History of Genius, Controversy, and Prestige
The late science historian Burton Feldman's comprehensive history of the prize.
Scientific Elite: Nobel Laureates in the United States
Published in 1977, this book by sociologist Harriet Zuckerman looks at the life and career trajectories of the scientific super-elite.
Could the birth of a four-dimensional black hole have created our three-dimensional universe?
That’s the idea put forth by the authors of a new paper on the arXiv preprint server1. Traditional Big Bang cosmology aligns well with many of today’s precision astrophysical measurements, they write, but it still leaves some important questions unanswered: In particular, what happened at the infinitely dense point, or singularity, from which the Big Bang sprung?
Artist's impression of a growing supermassive black hole. Image credit: NASA/CXC/A.Hobart
As Niayesh Afshordi, an astrophysicist at the Perimeter Institute for Theoretical Physics and one of the paper’s authors, told Zeeya Merali for Nature News, “For all physicists know, dragons could have come flying out of the singularity.”
“In the current best theories that we have, we know that we don’t know,” says Sean Carroll, a theoretical physicist at Caltech who was not part of the team that published the new paper. “We have theories of the universe that work really, really well, but they just don’t say anything about the Big Bang. They fail to give an opinion.” And when the equations of general relativity are applied to the Big Bang singularity, they pop out infinite answers. “What that really means is that the equations are breaking down,” explains Carroll.
Many physicists can stomach that breakdown as long as the singularity is quarantined behind an event horizon, an invisible boundary beyond which no information can pass to an outside observer. “If they [singularities] are ‘hidden’ behind event horizons, they do not affect our predictions, and so we can still use laws of standard physics,” says Afshordi. But the Big Bang singularity is not shielded in this way; instead it is what physicists call “naked.”
“’Naked’ singularities are not hidden, and thus anything to the causal future of ‘naked’ singularities will be affected by laws beyond standard physics,” says Afshordi.
Searching for a way to avoid the naked singularity at the Big Bang—and perhaps explain other vexing properties of our universe in the process—the authors of the new paper turned to a model of the cosmos called the “braneworld.” In the braneworld, our observable, three-dimensional universe actually lives inside another universe which has extra spatial dimensions. To use a two-dimensional analogy, our universe is like the skimmable membrane (“brane”) of fat on top of the pea soup of the universe.
We can’t detect this soup, called “the bulk,” directly, but it could explain some bizarre quirks of physics, like why gravity is so much weaker than the other fundamental forces. Yet physicists have not had much to say about what kinds of objects might live in the bulk and how they might affect us here on the brane.
The new paper analyzes what would happen if a black hole formed within the bulk. Unlike a regular old three-dimensional black hole, which is surrounded by a two-dimensional event horizon, a four-dimensional black hole would have a three-dimensional event horizon. And that event horizon would be constantly expanding. Sound like any universe you know?
The paper’s authors argue that this picture could address other mysteries of Big Bang physics, like how the universe settled down to such a uniform temperature so quickly. Physicists typically explain this problem using a phenomenon called cosmic inflation, which is believed to have caused the universe to swell up rapidly soon after the Big Bang. This swift, early expansion means that parts of the universe that seem disconnected today—that is, they are so far apart that they can’t exchange photons—could have “touched” in the distant past.
Inflation has passed nearly every test we’ve put it to. It even matches up nicely with the latest data from the Planck space observatory, which made the most precise map ever of the cosmic background radiation. The new black hole model doesn’t agree as closely with the Planck data. Plus, physicist Paul Halpern points out, “The authors have constructed something that needs to be closely manipulated and tweaked to get the parameters that inflation gets very naturally.”
Halpern also isn’t convinced that the problems the new model sets out to solve are truly so dire. The naked singularity that plagues the equations of general relativity might melt away once we have a theory that combines general relativity with quantum mechanics, says Halpern. The Big Bang singularity “doesn’t really trouble people who think there will eventually be a theory of quantum gravity.” Plus, Halpern points out, there are practical limits on our ability to observe the naked singularity at the beginning of the universe. “As we go back in time, it's harder and harder to make observations.”
It doesn’t seem likely that the Big Bang is going to be dethroned by the Big Black Hole anytime soon. But, says Halpern, “It’s important to be generous in terms of allowing for a wide range of theoretical models. You never know which will help us, ultimately.”
1The paper has been prepared for submission to the Journal of Cosmology and Astroparticle Physics, though it has not yet been peer-reviewed and published.
Author's picks for further reading
arXiv: 4D Gravity on a Brane in 5D Minkowski Space
In this academic paper, physicists Gia Dvali, Gregory Gabadadze, Massimo Porrati propose the brane world scenario on which the new paper is based.
The Nature of Reality: A Journey Into Extra Dimensions
In this video pencast, theoretical physicist Delia Schwartz-Perlov explains what physicists talk about when they talk about extra dimensions.
The Question of Cosmic Censorship
Physicist Roger Penrose on the problem of naked singularities and the possibility that physics may prevent them through “cosmic censorship."
How would it feel to fall into a black hole? Would you cruise pleasantly toward your doom, only feeling the deadly tug-and-crunch long past the point of no return? Or would you slam headlong into a scorching wall of fire at the black hole's event horizon? It might sound the like the plot of the latest summer blockbuster, but this question turns out to have profound implications for physics.
On Wednesday, September 25 at 3 p.m. ET/noon PT, the Kavli Foundation will be hosting a live webcast on this question, known as the firewall paradox, with four of the top researchers in the field, Raphael Bousso (U.C. Berkeley), Juan Maldacena (Institute for Advanced Study), Joseph Polchinski (U.C. Santa Barbara) and Leonard Susskind (Stanford University). Members of the public are invited to submit questions via email, and you can watch the webcast here or on the Kavli Foundation site.
Want to read up in advance of the event? Try the following primers:
Nature News: Fire in the hole!
The New York Times: A Black Hole Mystery Wrapped in a Firewall Paradox
Slate: New York Times Wants to Fight Einstein, Einstein Declines
Where will you be in 10100 years?
Yes, I know, we'll all be long gone by then. But if you could somehow stick around around to experience the universe ten thousand trillion trillion trillion trillion trillion trillion trillion trillion years from now, what would it be like?
Answering that question is a professional hobby for astronomers Fred Adams and Gregory Laughlin. They divide the life of the universe into five distinct stages, beginning with, well, the beginning—the Big Bang and the short period of explosive expansion that followed, all the way through to the formation of the very first stars about one million years later. That’s followed by the second stage, which Adams and Laughlin dub the “stelliferous era”—the era during which stars generate most of the universe’s energy. We are creatures of the stelliferous era; this is the universe we recognize as home.
But while the stars are hitting their stride during the stelliferous era, dark energy—the mysterious energy that is causing the expansion of the universe to accelerate—is well on its way to cosmic domination. If the acceleration continues at its present rate, in another hundred billion years or so, most of the visible universe will pass beyond our cosmic horizon. Future denizens of the Milky Way will turn their telescopes to the sky and see just one galaxy: their own.
As Lawrence Krauss and Robert Scherrer pointed out in a 2007 paper, these future astronomers will see no evidence of cosmic expansion or the Big Bang. They will probably conclude that their universe is static; that it is as it has always been and always will be. Ironically, the very force that sculpted their universe—dark energy—will have erased its own fingerprints.
This idea troubled Harvard astronomer Avi Loeb, who imagined a future in which astronomers would look back on today’s cosmology textbooks (which would then be 100 billion years old) with the same combination of reverence and skepticism with which we view biblical origin stories today. “You will have all these textbooks, but their claims will be unverifiable,” says Loeb.
Loeb went looking for a way in which future astronomers could tease out the history of their universe. He found the answer in hypervelocity stars, stars traveling so fast that they escape the gravity of their home galaxy. Using their advanced telescopes to monitor these stars, says Loeb, future astronomers just might be able to probe the universe beyond their galactic boundaries.
But even those galactic boundaries will be erased in the course of time. Astronomers estimate that the longest-lived stars will begin to burn out some ten trillion years from now, throwing our universe into an era of cosmic twilight. Here, the universe is lit only by the feeble embers of white dwarfs and neutrons stars, stellar corpses that will give off energy as they “hoover up” dark matter particles, says Adams. Though galaxies and galaxy clusters have managed to hold themselves together until now, a slow and steady stream of stars—the very same hypervelocity stars Loeb saw as cosmic ambassadors—will absent themselves from their galaxies until, over a period of about 1020 years, galaxies will “evaporate” entirely, Adams and Laughlin calculate. The finely-woven tapestry of the universe will come undone.
A computer simulation of the cosmic web of dark matter and ordinary matter. Image credit: NASA, ESA, and E. Hallman (University of Colorado, Boulder)
Given sufficient time, even the protons and neutrons that make up the stuff of universe will fall to pieces. How long will it take? That is still a mystery, though a combination of experiment and theory suggests that it will happen some time between 1033 and 1045 years after the Big Bang.
At that point, all that’s left of the stars and galaxies that once illuminated our universe will be a smattering of black holes. But even the reign of the black holes won’t last forever. As Stephen Hawking showed theoretically, black holes slowly leak out their contents via a process we now call Hawking radiation. Given enough time—as long at 10100 years—even the biggest black holes will evaporate away.
Only now will we enter what Adams and Laughlin dub the “dark” era. The dark era isn’t just very, very dark; it is also very, very boring. Next to nothing actually happens in the dark era. Thanks to the accelerating expansion of the universe, even humdrum particle collisions will become rarities.
Will the lonely monotony of the dark era ever end? Maybe. The same energy that has been driving the accelerating expansion of the universe could suddenly change character, a phenomenon theorists call vacuum energy decay. It happened once before—when the era of inflation ground to a halt soon after the Big Bang—and theorists believe that it should happen again.
“You could imagine a new start” for the universe, says Adams, in which matter gets a second chance to coalesce into stars, planets, even people. Or, the vacuum energy could decay before the universe ever makes it to the dark era. “If that happens,” says Loeb, “we’re back to a situation where once again we can see all those galaxies that we lost.”
Of course, these scenarios are a strong cocktail of science and speculation—and the further we look into the future, the more speculation is poured into the mix. So why study a universe that even our most distant descendants will never live to see?
The numerical models scientists use to project into the distant future can yield new insights into stellar life cycles—like how small, long-lived stars evolve into red giants—that we can’t observe progressing over the course of one (or many) lifetimes, says Adams. It also gives us a way “to gauge the cosmic importance of various aspects of the standard model,” says Loeb, by watching how they play out over time.
“It is part of our worldview to want to know what will happen,” adds Loeb. Yet I don’t think I’m alone in enjoying the fact that the next plot twist is, ultimately, a mystery.
Editors picks for further reading
Astrobites: Avi Loeb and Freeman Dyson on the future of the universe
Can the universe be saved from the "dark era"? Astronomy blogger Nathan Sanders shares a conversation between Freeman Dyson and Avi Loeb on the prospect of "cosmic engineering."
FQXi: Predicting the End
Science writer Govert Schilling talks with Fred Adams and Greg Laughlin about how they became the authors of the future-biography of our universe.
The Five Ages of the Universe: Inside the Physics of Eternity
Fred Adams and Greg Laughlin had the bad fortune to publish this book just around the time that dark energy was discovered; their predictions therefore don't account for dark energy. Most of their conclusions about the distant future remain valid, though.
When I see those victorious Olympic athletes all bedecked on the podium, beaming their gold-medal smiles and crying their gold-medal tears, I can’t help thinking: Now what?
And now that the coming-out party for the Higgs (or the Higgs-like boson, if you must) is over—the bubbly popped, the headlines receded—are physicists asking themselves the same question?
Certainly, physicists are not crying into their champagne. The discovery of a new boson right where the Higgs should be is a scientific tour-de-force. “It confirms, as it completes, the Standard Model of fundamental physics,” Frank Wilczek wrote here on the morning of the announcement.
And yet, science thrives on observations that don’t match up with predictions. Dark energy and dark matter, two of the greatest discoveries in a century of astrophysics, were hit upon because of the yawning gap between prediction and observation. If the universe is a puzzle, dark energy and dark matter are odd-shaped pieces that puckishly refuse to be wedged into place and, in their refusal, open up the possibility that the puzzle is actually richer and more complex than we ever anticipated. The Higgs, on the other hand, snaps right into place with a satisfying “Eureka!”
But if the puzzle of the Standard Model is now complete, where does that leave physics?
“There’s this huge looming question: The Standard Model works impeccably, but it leaves a lot of things unexplained,” says David Kaiser, a physicist and science historian at MIT. The Standard Model does not account for gravity, for instance, and it provides no explanation for why the physical constants take the particular values that they do. Like the periodic table of the elements, the Standard Model is an utterly faithful census of the ingredients that make up our universe. But while we know the elegant atomic underpinnings of the motley periodic table, we are still seeking the deeper laws that are expressed in the Standard Model.
“I always felt the best possible thing for the LHC would be to not see the Higgs,” says Peter Woit, a theorist at Columbia University. That would have cracked the Standard Model wide open, perhaps giving scientists a glimpse of the deeper physics underlying it. In this sense, says Woit, “The Standard Model is a victim of its own success.” Though it fails to answer some fundamental questions about out universe, it is so impervious to experimental contradiction—so perfect in its predictions—that physicists may soon find themselves at an impasse.
“If this is really the Higgs, then we have completed the Standard Model,” says physicist Peter Fisher of MIT. “We have created this model that describes exquisitely the world around us. We could legitimately say that, as a field of endeavor, we’ve done all there is to be done, and ask: Is this a place to stop and reassess?”
Physicists do have some guesses at what may lie beyond the Standard Model. There’s supersymmetry, for one, which suggests that elementary particles have mirror-image “superpartners” that differ in spin. Yet, to the surprise of some physicists, even the LHC has been unable to turn up any evidence of these superpartners. That suggests that, if superpartners are out there, they don’t possess the neat mirror-image symmetry we expected. Instead, the mirror that divides “us” from “them” may be warped.
“With the Higgs, you knew exactly what to look for,” says Woit. But the mirror of supersymmetry, if it exists, “could be warped in any arbitrary way,” leaving physicists to pursue an almost limitless game of hide-and-seek. And what if the superpartners—or other hints of new physics—are hiding where the LHC can’t find them?
But the story of the Higgs isn’t over yet. Over the coming months, physicists on the CMS and ATLAS teams will look to see whether this thing they have found decays in the ways they expect. Perhaps the new boson will turn out to be not so “vanilla” after all. Historically, it is often the “one last measurement to nail it down” that ends up taking physics in a new direction, Kaiser points out.
To Nobel prize-winning physicist Frank Wilczek, finding the new boson is just the beginning. “Having won this glorious battle, I'm psyched up for complete victory. We need to see some of the new particles that low-energy supersymmetry predicts. I think that will eventually happen at the LHC.”
“There is also room for gratuitous, but not perverse, speculation about the Higgs being a ‘portal’ into hidden sectors—hypothetical worlds of particles that have neither strong nor weak nor electromagnetic interactions,” adds Wilczek.
Yet Steve Ahlen, a Boston University physicist who helped build the ATLAS detector, thinks that the story of the quest for the Higgs has a somewhat different moral: “The most impressive thing about the success of the LHC, CMS and ATLAS is that thousands of people from all over the world, supported by tax dollars from many hundreds of millions of people, achieved success without the promise of fortune, power or fame, but for the simple joy of observing the beautiful world we live in. I think there is an important lesson to be learned from that.”
Watch this space the week of July 2, 2012 for a series of live webcasts from Fermilab and CERN on the latest results in the search for the Higgs boson.
Wednesday, July 4: CERN
Come back at 3 am ET on July 4, 2012 for a live webcast from CERN revealing the latest results in the search for the Higgs boson. A scientific seminar will begin at 3 am ET followed by a press conference at 5 am ET. Stay tuned!
Latest update in the search for the Higgs boson ©CERN
Press Conference: Update on the search for the Higgs boson at CERN on 4 July 2012 ©CERN
Monday, July 2: Fermilab
Tune in at 10 am ET on July 2, 2012 for a live webcast from Fermilab revealing the latest results from the Tevatron's CDF and DZero experiments in the search for the Higgs boson.
Higgs week is here!
This week, the search for the Higgs boson—the elusive subatomic particle that is a critical piece of the Standard Model of physics—may reach its climax when, on Wednesday, two research teams announce the results of their work at the Large Hadron Collider (LHC) at CERN.
But before there was the LHC, there was the Tevatron, a particle accelerator at Fermilab. And before the LHC’s big announcement, there was a not-quite-so-big announcement from the Tevatron teams as they gathered with colleagues this morning to announce the results of the most detailed analysis so far of ten years'-worth of their Higgs search data.
The Tevatron at Fermilab. Image courtesy of Fermilab.
The Tevatron shut down last year, passing the baton to the newer, more powerful LHC. But the scientists working on two of the Tevatron’s detectors, CDF and DZero, haven’t given up searching for traces of the Higgs in their own data. Using ever-smarter computer algorithms, they aim to wring as much information as they can out of the data they’ve accumulated. As Wade Fisher, the Michigan State University scientist representing DZero at this morning’s conference, put it: “We’re still working, we’re not stopping….There’s still gas in the tank.”
What they’ve found so far is suggestive of the Higgs, but doesn’t rise to the level of discovery. Combining data from both CDF and DZero, they’ve eked out a signal that might be due to the Higgs, but there is also a one-in-550 chance that it is down to random fluctuations.
To claim a discovery, the physicists need to whittle that random-chance number down to one in three and a half million—“five sigma,” in stat-speak.
That’s what the physics world will be holding its breath for on Wednesday, when two LHC collaborations release their results.
Will they confirm the hints that the Tevatron has seen? Or will these inklings—and our hopes of completing the Standard Model of physics--evaporate into the mist of random fluctuations?
As Fermilab’s Eric James put it this morning: “We’re likely, after all this time, to find something out one way or the other.”
If you thought that physicists couldn’t take a joke, a web site called arXiv begs to differ.
Arxiv is a preprint server, meaning that it’s where you can get an advance look at papers that haven’t yet been published in scientific journals. Of course, not every paper that appears on the arXiv is bound for The Astrophysical Journal. And every year, just around April Fools' Day, a crop of unusual papers tends to appear on the site.
After all, April Fools' Day brings out the geeky best in us all. So let’s celebrate the week of pranks and pratfalls with some highlights from this year’s April Fools' day haul:
Non-detection of the Tooth Fairy at Optical Wavelengths: "A wisdom tooth, freshly removed from the author’s lower left jaw, was placed under a pillow, upon which the author subsequently laid her head and fell asleep. The telescope was programmed to obtain an eight-hour time series of a six-meter-radius circle centered on the author’s sleeping bag. For a distance of 17 meters, the limiting absolute magnitude M is 99.7."
On the influence of the Illuminati in astronomical adaptive optics: "It is clear that the Illuminati are alive and well in modern times (Brown 2000). For instance, it is well known that pop stars Britney Spears and Lady Gaga have been aided in their astronomical rise to the top by the Illuminati (YouTube 2012). The secret to success in ground-based diffraction-limited astronomical imaging is less well known."
Gods as Topological Invariants: "We show that the number of gods in a universe must equal the Euler characteristics of its underlying manifold. By incorporating the classical cosmological argument for creation, this result builds a bridge between theology and physics and makes theism a testable hypothesis. Theological implications are profound since the theorem gives us new insights in the topological structure of heavens and hells. Recent astronomical observations can not reject theism, but data are slightly in favor of atheism."
And one from last year:
Schrödinger's Cat is not Alone: "Cat interferometry will inevitably lead to the 'Many Cats' interpretation of Quantum Mechanics, allowing to shed new light on old mysteries and paradoxes. For example, according to this interpretation, conservative estimates show that decision making of a single domestic cat will create about 550 billion whole universes every day, with as many replicas of itself."
Of course, arXiv isn't the only place to find physics pranks. The Museum of Hoaxes maintains a colorful list of the top scientific April Fools' Day pranks, including:
The bigon: On April 1, 1996 Discover magazine announced the discovery of a new subatomic particle, the bigon. According to scientist responsible for the breakthrough, Discover reported, "Bigons could be responsible for ball lightning, migraines, the unexplained failures of equipment and soufflés, the spontaneous human combustion."
The lost day: In 2004, Nature got in on the fun with a report the trade winds had blown an entire day—specifically, April 1—off the calendar.
Have you been a part of a great science prank? Tell us about it—or tell us about the prank you only wish you could pull off.
Physicists are on the brink of a breakthrough discovery: They may have finally cornered the Higgs boson, the subatomic particle hypothesized to give mass to all the stuff in the universe. But should we really be calling this particle the “Higgs”?
A computer simulation of a detection of the Higgs boson. Or is that the ABEGHHK’tH boson? Credit: David Parker/Photo Researchers, Inc.
Peter Higgs, it turns out, wasn’t the only one to come up with the idea of a new field (the Higgs field) that endows particles with mass. In fact, he wasn’t even the first to publish the theory. That distinction goes to Robert Brout and Francois Englert at the Free University in Brussels, who wrote up the idea in August 1964. Higgs was close on their heels with his own paper in October of the same year. Just a few weeks later, Dick Hagen, Gerald Guralnik, and Tom Kibble published their take on what would come to be known as the Higgs field and Higgs boson.
This wasn’t plagiarism: It was a kind of synchronicity that is the norm in science, says MIT science historian David Kaiser. In fact, independent research groups simultaneously arrive at similar breakthroughs so often that Robert Merton, a sociologist of science, put a name to the phenomenon: multiples. One famous multiple is calculus, which was simultaneously “discovered” by both Isaac Newton and Gottfried Leibniz in the late 17th century. More recently, the accelerating expansion of the universe was observed at nearly the same time by two competing groups of astronomers, both of which were honored with the Nobel Prize in physics in 2011.
Higgs, Brout, Englert and the rest were continuing a tradition that is as old as physics itself. But why is “Higgs” the name that stuck? “Higgs expressed the challenge”—how do we get particles that have mass and still obey the rules of symmetry?—“and the expected solution especially sharply,” says Kaiser. Another recounting pins the name on Ben Lee, a physicist who used “Higgs” as shorthand in a 1972 Fermilab conference program after having had a productive lunch chat with Higgs.
Higgs himself has always been uncomfortable seeing his name ride solo. He prefers to call the particle the “scalar boson” or the “so-called Higgs,” Ian Sample writes in his book “Massive.” Higgs has also advanced the uncommonly inclusive acronym ABEGHHK’tH—that’s the Anderson, Brout, Englert, Guralnik, Hagen, Higgs, Kibble and ‘t Hooft—to honor all the scientists who played a part in originating the theory.
Frank Wilczek, a Nobel prize-winning physicist who has named a few particles of his own (anyons and axions—the latter inspired by a laundry detergent), thinks that the alphabet soup solution would be “especially absurd.” Says Wilczek: “History is complicated, and wherever you draw the line there will be somebody just below it!”
If the Higgs discovery is confirmed, though, someone will have to draw that line—and that someone will be the Nobel Prize committee. The discovery is seen as a shoo-in for the physics honor, but the prize can be divided among no more than three laureates. There are at least six scientists with reasonable claims on the Higgs—not to mention the cast-of-thousands teams whose instruments are responsible for the experimental evidence that the Higgs actually exists.
Complicating matters is physicists’ anarchic naming methodology. When astronomers have planets, moons, and asteroids in need of naming, they turn to the International Astronomical Union. Elements get their formal names from the International Union of Pure and Applied Chemistry. Physicists, who have no such official naming body, have historically opted for descriptive names, like “neutrino” (“little neutral one”), or names devoid of any physical meaning at all, like “up,” “down,” and “charm.” As a particle named after a person, the Higgs is essentially alone among the fundamental elementary particles.
So what should we be calling the Higgs? “By now it's so deeply embedded in the literature that changing to another name would be jarring, and might introduce a gratuitous complication in literature searches or eventually even a hurdle to parsing older papers,” says Wilczek. If he had to choose? “A possibly better choice might be ‘zeron,’ to connote that the particle has zero quantum numbers, and in some sense is an ingredient of what we call nothingness.”
“I’d find a fancy-sounding word in ancient Greek, to give it gravitas, and then add ‘on,’” says Kaiser. In the absence of a Greek dictionary, Kaiser nominates “lardon”—a particle that makes things heavy.
Ultimately, it may come down to branding. “In business, it would be considered destructive to take a well-known name and replace it with a long-winded, technical-sounding alternative that no one has heard of,” wrote the editors of Nature in a recent editorial. Indeed, “Higgs” seems to have captured the public imagination—and it makes a much better Twitter hashtag than #ABEGHHK’tH.
Now it’s your turn: If you could rename the Higgs, what would you call it?
Editor's picks for further reading
Facebook: Peter Higgs
No, you can't "friend" him, but you can "like" him.
FQXi: Higgs Almighty
Whatever you call it, please stop calling it the “God particle,” says blogger William Orem.
PHD Comics: Higgs Boson Explained
In this video, particle physicist Daniel Whiteson at CERN explains how the LHC is searching for the Higgs boson.