What's Higgs boson? We, Fermilab try to explain
I grew up in the 1970s, which should explain a lot about my education.
If I recall correctly, only one year of science was required of high schoolers. Being the nerdy child of strict parents, I took three: biology, chemistry and special topics in biology. You'll note "physics" is not on the list.
I suspect many of us are in the same boat, then, when it comes to understanding why it was considered big news a couple of weeks ago that scientists think they have discovered evidence of the existence of the Higgs boson.
As a reporter who covers Fermi National Accelerator Laboratory, I've learned the boilerplate about the Higgs boson: Scientists think it gives mass to matter. If matter didn't have mass, gravity couldn't act on it, and matter would just fly around.
I'm suspicious enough about neutrinos, which are so tiny they are invisible but are apparently powerful enough to pass through hundreds of miles of rock from here to be registered at a detector in northern Minnesota. (Unlike, say, my index finger, which couldn't manage to get more than 2 inches into the drought-baked ground the same day as the announcement.)
So where in a clod of dirt do I find the Higgs boson?
And why was the July 4 announcement such a huge deal?
The announcement was "a pivotal moment" in explaining why things are the way they are, said Don Lincoln, the Fermilab scientist who tries to explain this to the general public and author of "The Quantum Frontier." Lincoln is one of about 1,000 U.S.-based scientists working on the Compact Muon Solenoid experiment being conducted at the Large Hadron Collider in Europe.
If matter did not have mass, we would not have atoms, he said. Without atoms (which make up molecules), there would be no life, he said.
On Earth, we tend to think of mass in terms of weight. But weightless objects in space still have mass. Lincoln suggested thinking of mass in terms of inertia. To move an inert object, a force must be applied.
In 1964, Scottish scientist Peter Higgs theorized that there was an energy field, through which subatomic particles passed and in which an unknown particle (a boson) acted on them, giving them mass. The proposed field and the boson were named after him. Higgs and other scientists outlined how they thought such a boson would behave, including how it would decay.
Scientists have been working to prove or disprove the idea since. And after accelerating protons and smashing them together, they looked at the decay patterns recorded and saw that some looked like Higgs thought they would. If they can prove there is a Higgs boson, then they can prove there is a Higgs field. Prove there is a Higgs field and you complete the Standard Model theory of physics.
Am I in the Higgs field? Does it pass through me?
It is everywhere, Lincoln said.
"Anywhere there is space there is a field. You cannot escape the Higgs field," he said. That includes the spaces inside atoms.
And how would a Higgs boson impart mass? Does it just glom on?
"We like to think of them bouncing off particles, in all directions," making it difficult for the particles to travel, Lincoln said. The particles become inert, and gravity can act on them. How that happens depends on the specific properties of the subject particles. In a video made for Fermilab, he likened it to the difference between a barracuda and a large man swimming through water.
"It is deeply, deeply fundamental," he said. "If you really turned off the Higgs field, the planet would just evaporate."
Scientists have a rating system for the credence of evidence. At a 4.9 sigma rating, the July announcement was pretty close to the "magic threshold" of 5, at which they think there is a 1-in-3.5 million chance the find was a fluke. Think of it like throwing a six-sided die. If it comes up 6 all the time, you would probably conclude the dice was loaded. But it could happen without being loaded.
The experiments at the Large Hadron Collider in Switzerland and France verified a few properties of what could be a Higgs boson, Lincoln said. They looked at five properties and were able to precisely measure two of them. What they saw behaved just as Higgs thought would happen. The other three are harder to measure, but they "did not do anything silly," Lincoln said.
The particle they think they found has nothing inside of it and has no electrical charge, as predicted.
But couldn't there really be something in there? Maybe another Higgs field, or another particle? And what would make a Higgs boson act the way it does?
It turns out there are people looking into that, Lincoln said.
Let's say everybody decides they've found the first Higgs boson.
Are there any practical applications? Not likely, Lincoln said.
So why spend nearly 50 years and billions of dollars, euros, lira, yen, rubles, francs and pounds looking for it, including building the Large Hadron Collider?
One answer is you don't know what you may come upon along the way (think Roentgen accidentally discovering the X-ray when he was studying cathode rays or Fleming discovering penicillin after mold infiltrated a bacteria-laden petri dish). And all the tools developed to look for subatomic particles -- the particle accelerators, the detectors, the computers -- "have tremendous applications," Lincoln said.
For example, look to the cancer-treatment centers that use linear particle accelerators to target tumors. Even the World Wide Web owes its existence to physicists stationed at CERN, who wanted a way to communicate and share data by computer with others around the world without having to cart tapes around.
But science isn't just about practicality. It is about human beings' constant quest to answer the ubiquitous question "why?"
As of July 4, "the universe is less mysterious than it was," Lincoln said.
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