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What do President Mohamed Morsy’s brain, the Constituent Assembly and Cairo traffic all have in common? None of them, alas, operate at the speed of light. In other words, they all have mass.
There’s nothing particularly astonishing about that observation, except that until earlier this month, scientists were a lot less certain about what gives the universe — including the elementary building blocks that make up brains, assemblies of people and cars — its mass.
One would think our high school physics teachers would have clarified this point, but it turns out that mass is not an inherent property of these building blocks. In fact, whenever physicists try to add the property of mass into their eye-aching equations, their mathematical models of the universe fall apart.
We can send people to the moon, but we don’t really understand where mass comes from. Fed up with this somewhat embarrassing problem, a few physicists in the ‘60s proposed something that sounds like it came out of a Deepak Chopra book.
There is a mysterious “field” that permeates the entire universe, the physicists cryptically suggested, and that field acts on other particles to give them their mass.
It was dubbed the Higgs field, named after British theoretical physicist Peter Higgs, one of the people to envision this ether-like solution to the problem of mass. But did it really exist, or was it just a mathematical trick that merely demonstrated how mass might come about, without actually bearing any relation to reality?
If it really did exist, the only way it could be detected was by hunting down any leftover excitations in that all-pervasive Higgs field. Such an excitation manifests itself as a particle called the Higgs boson. But could it ever be spotted?
‘The goddamn particle’
It may have cost US$10 billion and nearly 50 years to find it, but as of 4 July, scientists are now pretty certain they have spotted what is at least a “Higgs-like” particle.
Being so elusive yet critical to our understanding of the universe, American Nobel Prize winner Leon Lederman dubbed the Higgs boson “the God particle” — a moniker that stuck, much to the annoyance of physicists and especially Peter Higgs himself.
“I really, really don’t like it,” he told The Guardian on his 80th birthday three years ago. “It overstates the case. It makes us look arrogant. It’s rubbish.”
The frustration elicited by the particle’s elusiveness led Lederman himself to admit that “the goddamn particle” would have been a more appropriate term of endearment for the Higgs boson.
Ultimately, without finding it, the thing that was at stake of being termed “rubbish” was the Standard Model of particle physics — the so-called “theory of almost everything.”
While the Standard Model holds together neatly, having successfully predicted several elementary particles and force carries, nothing about this theory requires these particles to have mass. It was this glaringly missing ingredient that pushed physicists such as Higgs to postulate the existence of the mass-conferring boson named after him.
Its apparent discovery earlier this month lends further credence to the Standard Model.
How did they do it?
The process of spotting the Higgs boson entailed a lot of tiny collisions: 800 trillion of them, to be precise.
These collisions took place at the not-so-creatively-named Large Hadron Collider, an underground tunnel 27 km in circumference located at the European Organization for Nuclear Research, or CERN, near Geneva. The collider is a $10 billion physicists’ playground designed to smash together tiny particles, allowing scientists to investigate the resulting debris.
Two detectors, ATLAS and CMS, sifted through this debris, looking for intensity peaks associated with the Higgs boson. These were first detected and announced on 13 December.
By July, after making a few trillion more collisions just to be sure, the accumulated data suggested the boson was indeed detected. The chance that their findings were based on random fluctuations is only one in nearly 2 million — quite unlikely.
But you never know, hence the caution expressed in the discovery of what can only be officially described as a “Higgs-like” particle.
Ultimately, the mountains of data coming out of the collider will take months to interpret. Whether the results hint of new particles, bring us closer to a grand unified theory, or merely continue to confound us, remains to be seen.
The four forces
George Lucas never made it entirely clear which force he was referring to when he made Obi-Wan Kenobi intone those iconic words: “Use the force, Luke.”
Which one? The electromagnetic force? Gravitation? The strong nuclear force? The weak one? Those are the four fundamental forces of the universe known to scientists, and physicists are desperately trying to find evidence that they are all just a manifestation of one universal, unified force.
Uncovering a unified force is unlikely to endow physicists with Jedi powers, but it would bring them very close to formulating the Holy Grail of physics: a theory of everything.
Already, two of these fundamental forces — electromagnetism and the weak nuclear force, which is responsible for radioactive decay of subatomic particles — are known to be different manifestations of a single force called the electroweak force.
One of the goals of CERN’s Large Hadron Collider is to help determine whether this combined electroweak force, along with the strong nuclear force (which binds together the protons and neutrons that make up an atom’s nucleus), are also different manifestations of one universal unified force.
If discovered, the three forces would be unified, leaving only gravity — the fundamental force that has consistently refused to be made sense of using quantum physics. Even the fairly consistent and predictive Standard Model of particle physics has nothing at all to say about gravity, leaving its nature to be understood only through Albert Einstein’s general theory of relativity, which remains irreconcilable with quantum physics.
But some physicists insist that gravity must have a “force carrier,” an elementary particle called a “graviton” that mediates gravitational interaction. Force carriers have already been discovered for the other three forces: electromagnetism is mediated by photons, the strong force by gluons, and the weak one by W and Z bosons.
Likewise, with the mounting evidence for the Higgs boson, it appears there is an elementary particle to mediate the postulated Higgs field, which confers mass onto all things.
But what about gravitons, the hypothetical particles of gravity? If they exist, they are unlikely to be spotted any time soon. Gravitons theoretically require particle detectors far more massive than the Earth itself just to observe them.
Without evidence for their existence, or at least a fundamental shift in our understanding of the nature of particles, it is likely that physics will continue to fail to reconcile the Standard Model and general relativity for some time to come.
This piece was originally published in Egypt Independent's weekly print edition.