Finding the Anti-World The Next Holy Grail for Physics
The apparent discovery of the Higgs boson was hailed as a historic milestone, but for particle physicists it mainly marks the beginning of a new search. Rival teams at CERN in Switzerland are trying to decipher the secrets of antimatter. If they succeed, the laws of physics will have to be rewritten.
Sheep are grazing to the left of the gate to the anti-world. On the right-hand side, a pair of rust-brown steel bottles is waiting to be picked up. A sign warns: "Caution. Radiation!" Another sign prohibits the use of bicycles.
A yellow steel door leads into the interior of the so-called AD building on the grounds of the CERN research center near Geneva, Switzerland. The machine that was built here is called the anti-proton decelerator. The rhythmic hissing and thumping sounds of vacuum pumps and cryo-aggregates combine with the dull droning of the air-conditioning system. This is where scientists are making a material that is highly mysterious because it probably doesn't exist anywhere else in the universe: anti-atoms.
About 4 meters (13 feet) off the ground, a catwalk leads through a bizarre landscape of cables, tubes and concrete. This vantage point offers a glimpse into laboratory rooms in which scientists climb around among magnets, electronic equipment, helium tanks and beamlines. Their goal is to explore the realm of antimatter.
Separated from each other by small gates, four teams are competing to unlock the secrets of nature. Their facility is a factory of sorts for so-called anti-particles. Here, the scientists guide, cool, slow down and centrifuge the artificially generated particles. In the process, they learn which forms of manipulation are possible with this material from a mysterious alternative world. One of them calls it "particle gymnastics."
'The Race Is On'
The words "The race is on" are written on the container where the measurements are done. Jeffrey Hangst, the director of the project, is proud of the fact that his team is ahead in the race. Hangst spent 15 years developing his equipment, and now he is reaping the benefits.
Hangst is the world's first scientist to successfully capture individual anti-hydrogen atoms in magnetic traps. No one else has managed to keep the atoms captive for an entire quarter of an hour. And then, in what was a sensation for physicists, he performed the first successful measurement of one of these antiatoms.
The accelerator ring where Hangst does his experiments was once the centerpiece of CERN, earning the center international fame and its developers, Simon van der Meer and Carlo Rubbia, the Nobel Prize. Today, however, the anti-proton decelerator is hidden in a dead-end street. The antimatter factory isn't easy to find among the office buildings, workshops and machine buildings at CERN.
Public attention has long since turned to the new, enormous super-accelerator called the Large Hadron Collider (LHC) -- especially in recent days.
Last week, physicists at CERN proudly announced that the LHC had achieved its first important partial victory: The data that were presented at the major summer conference of particle physicists in Melbourne leave almost no doubt anymore that the so-called Higgs boson, which gives other particles their mass, has finally been found. The discovery marks the end of a hunt that has lasted almost 50 years.
'The Work Has Just Begun'
"It's hard not to get excited by these results," says Sergio Bertolucci, the research director at CERN. He and his colleagues agree that this is a great moment in the history of their field -- perhaps the discovery of the century. And yet it was also a discovery that they had all expected. It would have been more surprising if they had not found the Higgs particle, because it would have destroyed the current standard theory of particle physics.
Seen in this light, the scientists are not as excited about what they have finally achieved as they are about what lies ahead. "The real work has just begun," says CERN Director General Rolf-Dieter Heuer.
That's because the discovery of the Higgs boson merely serves as yet another confirmation of an existing theory. Physicists agree that they are now entering terrain in which they will no longer be guided by the existing equations. What happens next is uncertain.
The known formulas are not sufficient to help us understand why the world is this way and not that, and to comprehend in detail how the universe was created during the Big Bang. To delve into those secrets, it will be necessary to decipher new laws of nature.
Whatever Happened to Antimatter?
One of the central puzzles that could pave the way into this new territory lies in the question that Jeffrey Hangst has chosen to pursue: Why does the world consist of matter? And what happened to antimatter?
Hangst is particularly interested in an unusual material. It behaves just like ordinary matter, and yet it's completely different. The properties are the same, meaning that anti-glass would splinter like glass, anti-gold would shine like gold and anti-water would splash like water. And there would also be no visible difference between a person made of normal matter and a person made of antimatter. They would be completely identical.
But heaven forbid that both -- matter and antimatter, image and copy -- come into contact with one another. If that happened, there would be a bright flash of light and suddenly both would have disappeared.
The most important thing, however, is the fact that antimatter doesn't actually exist on a sustained basis. The anti-world is nothing more than a possibility, one that nature has apparently not made into a reality. In the theorists' equations both the world and the anti-world play equal roles. But in the real, observable universe, everything consists of matter, not antimatter.
"Understanding why this is the case has always fascinated me," says Hangst. Physicists are convinced that properly understanding the relationship between matter and antimatter would be tantamount to a revolution in comprehending the universe.
Something Instead of Nothing
Back in the mid-19th century, German philosopher Friedrich Wilhelm Schelling came up with what he called the "final, desperation-filled question": Why is there anything at all? Why is there not nothing? In modern physics, Schelling's metaphysical astonishment has been rephrased: Why don't matter and antimatter exist in equal parts in the universe?
Physicists agree that the force of the Big Bang created both forms of existence in equal amounts. With each particle, its counterpart, the corresponding antiparticle, was born. And because nature gave both the capacity to destroy one another, the moment of their creation already included the seeds of their demise.
But then some providential change must have fundamentally altered the course of the universe. Physicists would love to understand what exactly happened shortly after the Big Bang. At this point, they only know the results of those events early in the history of the cosmos: They led to matter gaining the upper hand over antimatter.
But by no means was it by a large margin. On the contrary, the ratio that once existed between the two types of particles can be calculated using the density of particles in today's universe. The result is astonishing: There were 1,000,000,001 particles to 1,000,000,000 antiparticles. Can such a miniscule imbalance be significant?
Yes, it can. The subsequent evolution of the universe would reveal that this one particle was critical. If matter and antimatter had been exactly equal, cosmic existence would have destroyed itself within fractions of a second, leaving nothing behind but a monotonous desert of radiation.
No galaxies, no stars and no planets, and not even the most ordinary of atoms would have been created in the universe without this small imbalance -- and humanity would certainly not have had the opportunity to ponder the mysteries of existence. The universe would have been nothing but a massive, constantly expanding ball of light.
Thanks to this tiny imbalance, however, there were survivors of the cosmic conflagration. In a furious inferno, matter and antimatter were incinerated, yielding pure radiation energy, which still exists today in the form of the background radiation that fills the entire universe. But the small remnant, that tiny excess of matter, survived and formed the seed of everything we marvel at today in the starlit sky. And everything that forms mountains, oceans, plants, animals and human beings on the Earth also stems from the remnants of that huge orgy of destruction that marked the beginning of cosmic history.
Ever since physicists recognized that all the diversity and complexity in this world is attributable to the victory of matter over antimatter, one of the great challenges of their field has been to solve the question of what caused that mysterious imbalance in the first place. Although physicists have been able to reconstruct the processes of the Big Bang in astounding detail, this fundamental question still remains unanswered.
But now the big search for answers has begun, a search that involves the use of technology on a massive scale:
- At the Brookhaven National Laboratory outside New York City, scientists are smashing together gold ions at nearly the speed of light. Last year, they managed to identify 18 anti-helium nuclei, the largest antiparticles detected to date, in the inferno of many billions of particle fragments.
- In a bid to detect even larger particles of antimatter, particle physicists have set up experimental apparatus in space. Their detector, which is docked to the International Space Station (ISS), has been listening for signals from the anti-world since May of last year.
- In Japan, scientists are bombarding a tank filled with 50,000 tons of highly purified water with neutrinos. Their goal is to detect tiny differences in the properties of neutrinos and their antiparticles, anti-neutrinos.
- One of the four massive underground detectors at the LHC at CERN is devoted primarily to one task: detecting differences in the behavior of matter and antimatter.
- Part 1: The Next Holy Grail for Physics
- Part 2: How 'the Strangest Man' Revolutionized Physics
- Part 3: Searching for Antimatter in Space