New research suggests that scientists can split the electron. Is nothing sacred, asks Philip Ball?
Philip Ball
2,400 years after the Greek philosopher Democritus proposed the irreducible atom and more than 80 years after Ernest Rutherford first split it, the idea that these building blocks of matter are not, as their name implies, indivisible, is commonplace. Atoms are split daily in nuclear reactors.
Now Humphrey Maris at Brown University in Rhode Island, USA, is proposing something even more shocking to scientific orthodoxy. He thinks that electrons can also be split -- into fragments called 'electrinos'.
The British physicist J. J. Thompson discovered the electron in 1897 (for which he won the 1906 Nobel Prize in physics). He deduced that the 'cathode rays' that now brighten television screens are beams of these tiny, electrically charged subatomic particles.
Then around 1912, Rutherford and the Danish physicist Niels Bohr proposed that atoms consist of electrons orbiting around a dense nucleus of other subatomic particles. In essence this is the prevailing picture of the atom today.
The nuclear particles -- protons and neutrons -- are believed to comprise still more fundamental particles called 'quarks'. Electrons, conversely, are thought to be indivisible. They are 2,000 times lighter than protons and at least 100 million times smaller than an atom.
If the electron were 'splittable', one might expect to detect particles with some fraction of the electron's negative electrical charge. None such have ever been reported (although electrons in solids can sometimes conspire to appear to have smaller charges). One could be forgiven for thinking that there is not a scrap of evidence in support of an 'electron fragment'. But Maris has found some.
He has looked again at experiments first conducted in the 1960s and 1970s. In these, electrons were injected into liquefied helium (which exists only at minus 269°C, about 4 degrees above absolute zero).
Electrons in helium behave in a puzzling way, for which there is not, as yet, a fully satisfactory explanation. They create tiny bubbles, about 4 millionths of a millimetre (roughly 400 atom widths) in diameter, that no helium can enter. When light is shone on these bubbles, new unidentified, negatively charged particles seem to appear.
Low-temperature physics is full of such oddities. The puzzle was that the light did not simply kick the electrons back out of the helium. In fact, it was not clear what had happened to them. Maris suggests that the electrons had split apart.
He proposes that light causes the bubbles to oscillate, until they break up like shaken raindrops. Within the initial bubble, he says, the electron behaves as a kind of wave. When the bubble splits, each fragment takes a part of the electron wave with them -- an 'electrino'.
Maris says that this behaviour is possible in liquid helium because it behaves as a 'superfluid', which flows with apparently zero viscosity. So the bubble oscillations leading to break-up are not muffled as they would be in a normal liquid.
Maris has published his idea quietly in the Journal of Low Temperature Physics1, but it is sure to arouse controversy. Some physicists, such as Gary Ihas at the University of Florida, say that more conventional explanations for the mysterious charged particles produced by the light have not yet been ruled out. But Peter McClintock at Lancaster University in the UK, an expert in low-temperature physics of helium, calls Maris's paper, "extremely interesting".
http://www.nature.com/news/2000/000915/full/news000921-1.html
New research suggests that scientists can split the electron. Is nothing sacred, asks Philip Ball?
Philip Ball
2,400 years after the Greek philosopher Democritus proposed the irreducible atom and more than 80 years after Ernest Rutherford first split it, the idea that these building blocks of matter are not, as their name implies, indivisible, is commonplace. Atoms are split daily in nuclear reactors.
Now Humphrey Maris at Brown University in Rhode Island, USA, is proposing something even more shocking to scientific orthodoxy. He thinks that electrons can also be split -- into fragments called 'electrinos'.
The British physicist J. J. Thompson discovered the electron in 1897 (for which he won the 1906 Nobel Prize in physics). He deduced that the 'cathode rays' that now brighten television screens are beams of these tiny, electrically charged subatomic particles.
Then around 1912, Rutherford and the Danish physicist Niels Bohr proposed that atoms consist of electrons orbiting around a dense nucleus of other subatomic particles. In essence this is the prevailing picture of the atom today.
The nuclear particles -- protons and neutrons -- are believed to comprise still more fundamental particles called 'quarks'. Electrons, conversely, are thought to be indivisible. They are 2,000 times lighter than protons and at least 100 million times smaller than an atom.
If the electron were 'splittable', one might expect to detect particles with some fraction of the electron's negative electrical charge. None such have ever been reported (although electrons in solids can sometimes conspire to appear to have smaller charges). One could be forgiven for thinking that there is not a scrap of evidence in support of an 'electron fragment'. But Maris has found some.
He has looked again at experiments first conducted in the 1960s and 1970s. In these, electrons were injected into liquefied helium (which exists only at minus 269°C, about 4 degrees above absolute zero).
Electrons in helium behave in a puzzling way, for which there is not, as yet, a fully satisfactory explanation. They create tiny bubbles, about 4 millionths of a millimetre (roughly 400 atom widths) in diameter, that no helium can enter. When light is shone on these bubbles, new unidentified, negatively charged particles seem to appear.
Low-temperature physics is full of such oddities. The puzzle was that the light did not simply kick the electrons back out of the helium. In fact, it was not clear what had happened to them. Maris suggests that the electrons had split apart.
He proposes that light causes the bubbles to oscillate, until they break up like shaken raindrops. Within the initial bubble, he says, the electron behaves as a kind of wave. When the bubble splits, each fragment takes a part of the electron wave with them -- an 'electrino'.
Maris says that this behaviour is possible in liquid helium because it behaves as a 'superfluid', which flows with apparently zero viscosity. So the bubble oscillations leading to break-up are not muffled as they would be in a normal liquid.
Maris has published his idea quietly in the Journal of Low Temperature Physics1, but it is sure to arouse controversy. Some physicists, such as Gary Ihas at the University of Florida, say that more conventional explanations for the mysterious charged particles produced by the light have not yet been ruled out. But Peter McClintock at Lancaster University in the UK, an expert in low-temperature physics of helium, calls Maris's paper, "extremely interesting".