Perhaps the greatest mystery in science today is why are we here – and not metaphorically.
Material existence confounds a pet theory of physics, which is that every creation of matter simultaneously creates an equal amount of antimatter, and matter and antimatter cancel each other out. But everything we observe is made of matter. Where’s the antimatter?
Maybe we’ll gain insight into that conundrum and many more after the CERN Council last month accepted the recommendations of its strategy-guiding committee, the European Strategy Group for Particle Physics, chaired by the celebrated physics professor Halina Abramowicz of Tel Aviv University’s Faculty of Exact Sciences.
“We still don’t understand how come we exist,” Abramowicz tells Haaretz. And addressing matter-antimatter asymmetry, what happened in the early universe to basically make antimatter vanish, is just one of the existential mysteries to which CERN intends to devote itself.
CERN – the Conseil Européen pour la Recherche Nucléaire (the European Organization for Nuclear Research) – was established in 1954, in the wake of World War II. It was founded by “smart people” to pursue large, expensive projects that the war-scarred individual countries couldn’t afford. Building the famed Large Hadron Collider cost over $6 billion, albeit over a decade. CERN’s current yearly budget, to put things in proportion, is $1.3 billion. Its electricity bill alone is tens of millions of dollars a year. (A "hadron" is any particle made of quarks; protons contain quarks, among other things, and are therefore hadrons; the LHC smashes protons together. That's what it does.)
CERN operates out of Switzerland with some operations in France, but the convention ensures member nations can treat its territory as their own: their people have a status akin to diplomatic. Israel has been a full member since 2014 and gets to “eat at the table” – ergo, vote on CERN decisions. Naturally, it has to contribute to CERN’s budget too, ponying up about $15 million a year. Israel’s representative on the CERN council is Prof. Eliezer Rabinovici of the Hebrew University.
Abramowicz, who had previously represented Israel on the scientific committee devoted to ensuring that the goals of the giant particle accelerator at CERN and of the countries’ own small accelerators did not compete, was elected chairwoman of the strategy committee in 2017.
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CERN’s newly embraced strategy includes building an even larger proton-proton collider, 100 kilometers (60 miles) long, at a projected cost of at least $25 billion.
How to put this: Given the mounting desperate nature of the times, with the coronavirus and global recession around one corner and climate change around the other, why should Europe invest that much and more in particle physics?
“We are the language of science. It permeates the sciences,” Abramowicz answers. The purpose of delving into the mysteries of particle physics is precisely to make order in our bewildering universe.
The mystery of being
Before peering into the future, this is a good point to ask what CERN has done for us in the past, besides satisfying at least some scientific curiosity and being a “muse” for sci-fi B-movies about the inadvertent creation of homegrown black holes.
The answers include saving lives and the ability to almost instantly exchange cat pictures.
CERN develops particle accelerator technology and measurement techniques that benefit society at large: thousands of small accelerators around the world now serve in medical, industrial and security applications, Abramowicz explains. Israel also has a bitty one, at Nahal Soreq, to study the structures of molecules and materials. Jordan houses a Middle Eastern accelerator collaboration of its own, wonderfully known as the Synchrotron-light for Experimental Science and Applications in the Middle East (SESAME).
In addition, the concept of the internet was initially developed by the U.S. military in the late 1960s, but CERN took it to the next level as a tool for scientists to communicate. “Browsers are based on technology invented at CERN,” Abramowicz says, slaking the human thirst for data-heavy cat photos.
For the scientists, CERN’s key value is basic research driven by curiosity, not applications. “Our ambition is to understand the basic constituents of matter and their interactions,” Abramowicz explains.
It’s been a long time since the atom was considered the most basic particle of matter. By now, the list of subatomic particles has grown to include multiple quarks, leptons, bosons and gluons, and, most recently, the Higgs boson – dubbed the “God particle” by the media. Haaretz promises not to dwell on what these are.
Physics is the base of everything. Chemistry and biology have to obey the laws of physics. A kangaroo will hop based on the physical and biological laws governing its existence. Which brings us back to why the kangaroo or anything else exists. We don’t know, and elucidating the matter-antimatter asymmetry conundrum is one of the major goals for CERN set by the strategy committee.
The language of dark matter
Another goal is to learn about dark matter beyond the indirect evidence that it exists.
“Everybody knows we have dark matter,” says Abramowicz, perhaps overstating the case. Nobody has seen it or has any notion of how to sense it or what it might be. Dark matter (and dark energy) are theorized to exist because, based on the matter we can recognize, physics today can’t explain the existence and movement of the galaxies. The “missing mass” that would explain the galaxies’ behavior is called “dark matter” – as in, we’re in the dark about it.
“It’s very frustrating,” she admits. “From the point of view of particle physics, dark matter should be a particle, or some particles. We wanted to create it at the Large Hadron Collider and still want to, but haven’t managed yet.” After some 12 years of endeavor and collecting data, they have no candidate particles. The hope is that the new 100-kilometer proton-proton collider they envision will contribute to this endeavor.
A third goal set by the strategy committee is to shed light on the mass of neutrinos, which in contrast to past theory that these subatomic particles have no mass, actually do. Not much perhaps. They also oscillate, and one neutrino can change into another type of neutrino. “We know how neutrinos are created, but don’t know what mechanism is responsible for their mass, what its origin is,” Abramowicz says. This field is very exciting to particle physicists.
And that is the upshot of the strategy committee. CERN has a policy of periodically updating its strategy, about every 10 years. Thus, the strategy committee was set up about two years ago: it takes time to design the road map, Abramowicz points out. The chairperson of the strategy committee is elected by the CERN council based on recommendations, and neutrality.
Abramowicz, born and educated in Poland and today an Israeli too and a leading figure at Tel Aviv University, was nominated among one of many candidates, she says. Her election is just the latest of a string of international achievements in her résumé.
So, again, why should Europe invest $25 billion in a new proton-proton collider? “I think the future of physics is essential,” she explains. “It’s the language of all science, as mathematics is the grammar. There’s no science without physics. It’s at the top of every single science. They all use the tools of physics. Science has cultural merits; it gives us tools to better understand the universe.”
If you hate protons and crazy people, stop reading here
The futuristic 100-kilometer collider the council recommends building will, like the Large Hadron Collider, smash protons into protons. Why protons? “Because we know how to control the proton. As far as we can tell, it has an infinite lifetime. It doesn’t decay and that’s very important to our existence,” she explains.
Now, electrons don’t decay either – they’re also elementary particles – but they’re like particle fairies, light and relatively insubstantial, while protons are heavy. “We know how to accelerate them. Electrons are very light and if we try to manipulate them, they have the nasty property of immediately starting to radiate energy.” In a circular accelerator, the faster they go at high energies, the more energy they lose, which isn’t useful for our purposes.
Apropos energy, if generating it is the goal, then the optimal collision would be between electrons and positrons (aka antielectrons, or the antimatter counterpart of the electron), Abramowicz says: their meeting annihilates both, resulting in “fully democratic energy that can be spent on anything the universe has – almost like going back to the Big Bang.”
The snag about the proton-proton colliders is that protons aren’t elementary (indivisible) particles, they’re like bags full of elementary particles, quarks and gluons. So when they collide, the result is messy. “If we’re lucky, we can produce quarks and antiquarks. But there’s lots of background noise that floods our data and detectors,” Abramowicz explains. The output of a collider for elementary particles would be cleaner.
And that is the highest priority in the new CERN strategy, she says: to design an electron-positron collider (this is beyond the 100-km proton-proton collider). For an electron-positron collider they need to build a “Higgs factory” that would produce a wealth of Higgs particles – the elementary particles whose discovery in 2012, based on work at CERN, was hailed worldwide. Particle physicists tend to cringe at the “God particle” soubriquet. But let’s face it, for the rest of us, accepting what they’re doing there is a matter of faith.
That said, even the futuristic Higgs collider may not have enough energy to shed light on that most mysterious thing: dark matter, which is why CERN aspires to build that 100-kilometer circular collider, about four times longer than the LHC, which is presently the biggest machine in the world. And ultimately, for the faithful among us, Abramowicz explains: they could theoretically achieve electricity transfer systems that do not dissipate energy. “None of this will happen without very strong motivation by very crazy people,” she sums up. We have faith.