SCIENCE & ENGINEERING NEWS
San Francisco, CA — For a century, physicists have assumed that the electron – that subatomic workhorse of science and technology – is indivisible: You can’t chop it in half like a meatloaf. But as Keay Davidson reported for the San Francisco Examiner, that old wisdom may be dead wrong, judging by the puzzling results of experiments that have thrown the physics world into a tizzy.
Electrons may be divisible after all, reports leading physicist Humphrey Maris of Brown University. He bases his claim on experiments involving electrons trapped in bubbles that float through an eerie, super-cold substance called liquid helium.
Physicists have reacted to Maris’ claim with emotions ranging from amazement to bafflement to disbelief. “It’s fascinating. My immediate response was it’s not possible, but I’ve been wracking my brains for why it’s not possible and I’m not sure. I just don’t know one way or the other,” said Princeton University physicist Philip Anderson, co-winner of the 1977 Nobel Prize in physics.
If Maris’ theory is verified, then “it means that elementary particles are no longer what everybody thinks. It’s a major change,” says physicist Sebastien Balibar, director of research at the Ecole Normale SupÈrieure in Paris, who also is associated with Harvard University.
Without electrons, modern civilization would fall apart. These subatomic particles make possible innumerable gizmos from TVs to toasters and computers to camcorders. From coast to coast, Niagaras of electrons stream through electrical transmission lines.
In fact, without electrons, all matter – you and the surrounding Earth and universe – would dissolve like fog. Electrons are the primary electrical “glue” that binds atoms into molecules, the building blocks of visible reality.
The electron has been intensely scrutinized by physicists for the last century, ever since British scientist J.J. Thomson confirmed its existence and Caltech researcher Robert Millikan measured its minuscule electrical charge. Billions of taxpayers’ dollars have bankrolled giant particle accelerators that spin electrons about like angry bees, bashing into other particles and exposing their innards.
After all that hard work, physicists can’t be blamed for assuming that they had a pretty good idea what an electron is: the ultimate, indivisible, unsplittable “unit” of negative electrical charge.
There’s plenty at stake. According to the so-called “Standard Model” of physics – physicists’ version of the U.S. Constitution – the electron is one of the fundamental building blocks of matter. Matter supposedly comes in two broad classes: “quarks” (the building blocks of protons and neutrons, the guts of atomic nuclei), and “leptons” (the best-known being electrons).
All quarks and leptons are supposed to be indivisible. But Maris’ work suggests that at least one type of lepton, the electron, can be split. On this basis he suggests that other subatomic particles might also be divisible.
Maris first openly challenged the assumption that electrons are indivisible in June, when he reported his experimental findings at the “Quantum Fluids and Solids” conference in Minneapolis.
“Some in the audience believed him, others did not; all were interested in what he had to say,” said physicist Robert Hallock of the University of Massachusetts-Amherst in an e-mail interview with The Examiner. “His ideas are likely to be very controversial because they question what has been solid scientific belief about electrons and quantum physics for decades.”
At the meeting, “although he (Maris) received a lot of flak – a huge number of critical questions and objections – he stood his ground and, in my opinion, dealt effectively with them all,” said physicist P.V.E. McClintock of Lancaster University in England, who also attended.
Although Maris realizes he’s challenging scientific shibboleths, he has a sense of humor about it: “I’m not a crank physicist by any means – I’m a conservative old fuddy-duddy,” he said with a laugh. Still, if he’s right, his discovery would be “a pretty amazing thing for physicists . . . a radical change (in thinking).”
Maris has “a superb scientific reputation” and “the (scientific) stature to be taken seriously,” Hallock said. Anderson calls Maris “a highly respected person.” Ben Stein, a spokesman for the American Institute of Physics in Washington, called Maris “a distinguished and reputable physicist.”
In the early 20th century, scientists assumed electrons were distinct particles, like marbles. But reality is more complicated, as researchers showed in the 1920s. Back then, the concept of “quantum mechanics” was revolutionizing physics. Quantum mechanics held that on the subatomic level, matter and energy are “fuzzier” than they appear on the everyday, macroscopic level – the level of human beings, TVs, and toasters.
In seeming violation of common sense, matter and energy take on ghost-like qualities at the quantum scale: Particles move instantaneously from one place to the next in a random manner that can’t be predicted with classical rules of physics, only with statistics.
Indeed, an electron has a “wave function” – it’s less like a hard, indivisible particle than like a series of ripples on a pond. The ripples indicate where a single electron is statistically likely to materialize at any given moment. (It’s sort of like the gopher in the movie “Caddyshack” that momentarily pops its head up at the golf course, then a moment later pops up somewhere else, and so on.)
This notion of “electron waves” was first suggested in the 1920s by the French physicist-aristocrat Louis de Broglie, whose work Albert Einstein welcomed with near-religious praise: “He (de Broglie) has lifted a corner of the great veil.”
Bizarre though it seemed, de Broglie’s idea was readily verified in experiments by Bell Laboratories physicists C.J. Davisson and L.H. Germer, who subsequently shared the Nobel Prize in physics. (De Broglie won a separate Nobel.)
So when Maris says that an electron can be split, what he literally means is that the electron wave function can behave even more oddly than de Broglie, Davisson and Germer thought: Literally, the electron “waves” can be split apart, over an unknown distance – at least a few feet apart.
In effect, one moment an electron can be at point A, then instantaneously reappear at Point B a few feet away, as if “teleporting,” to use “Star Trek” lingo, between the two points.
Maris’ theory relates to lab experiments that involve a frigid vat of liquid helium. This is a liquefied form of the second-lightest element, helium. Inside the vat, he generates electron “bubbles,” each one hundred-billionths of an inch wide.
His theory predicts that these bubbles can be divided into smaller bubbles, each containing a part of the “wave function” of the electron. In the process, he appears to have split individual electrons into fragments, although this clearly violates the Standard Model of physics. He calls the electron fragments “electrinos.”
Is Maris right? Is fundamental physics due for an overhaul? Or will future historians of science remember him as one of many esteemed-but-wrong researchers who thought they had overturned, or at least shaken, Mother Nature’s apple cart?
“He may be wrong, and many do not accept what he has proposed,” Hallock said. “Others, including me, have some questions about what he has proposed, but accept the ideas as interesting, potentially very exciting, and look forward to the experimental tests that should enhance our understanding and ultimately test whether Humphrey is right or not.”
If validated, does Maris’ work offer practical applications? It’s too early to say, but he suggests that the ability to split electrons might lead to faster microchips, semiconductors and computers – exactly how, he can’t be sure.
In any case, Maris’ work reinforces Einstein’s famous crack that reality is not only weirder than we imagine, but perhaps weirder than we can imagine. As Maris observes, that’s why physicists, when asked by lay people to explain what is “really” going on at the subatomic level, may sound more like philosophers than scientists.
As Maris says with a laugh: “It’s a little bit like President Clinton saying, ‘It depends what you really mean by is.’ ”