From: Eliezer S. Yudkowsky (email@example.com)
Date: Sun Dec 10 2000 - 15:41:18 MST
This is one of the strangest things I've ever heard. Preliminary poking
around on the 'Net seems to confirm that Humphrey Maris is a genuine,
respected physicist, and that the people quoted in the articles are
likewise genuine. Though with news like this I wouldn't be in the least
surprised if someone corrected me and said he had known newts in the
belfry. If it is true, I'm very surprised there's been less flap about
Can the electron be cut in half?
AT THE TIME no one even realised it had happened.
More than thirty years ago, researchers in Minnesota did
the unthinkable and broke the "indivisible" electron into
fragments. This, at least, is the contention of British
physicist Humphrey Maris, and no one has yet been able
to prove him wrong. "Electron fragments behave to all
intents and purposes like entirely separate particles," says
Maris, who is based at Brown University in Rhode Island.
"I call them electrinos."
Pause a moment to consider what Maris is saying. The
electron is the lightest subatomic particle and the one with
the greatest claim to being absolutely fundamental. In fact,
in the 103 years since its discovery, there has been no
other evidence whatsoever that the electron is divisible. It
is the modern incarnation of Democritus's "uncuttable"
The claim that electrons are divisible is therefore nothing
short of a bombshell dropped into the world of physics. "If
Humphrey is correct, it means a Nobel Prize," says Gary
Ihas of the University of Florida. Nobel prizewinner Philip
Anderson of Princeton University thinks Maris must be
wrong. "But it's not obvious why," he admits.
Maris does not have definitive proof of his hypothesis. But
earlier this year he published a paper that put it on a firm
theoretical basis, and marshalled supporting evidence
from past experiments. Now he is doing his own
experiments, trying to break up the electron.
Whether Maris succeeds or not, he may have found a
large crack in one of the foundation stones of modern
physics. "Humphrey has succeeded in exposing a
fundamental flaw in the framework of quantum theory,"
says Peter McClintock of the University of Lancaster.
This astonishing heresy is centred around the electron's
wave function, the mathematical entity that, according to
quantum theory, encapsulates everything about the
electron that it is possible for us to know. Among other
things, an electron's wave function describes the
probability of finding it at any particular location. The wave
function of an electron confined to, say, a spherical cavity
is the three-dimensional description of how the electron's
location is "smeared out" over the space.
In its lowest energy state, the wave function is spherical.
The next highest energy level gives the wave function a
dumb-bell shape. "It was while thinking about this state I
was led to the conclusion that an electron might split in
two," says Maris. If the dumb-bell could be stretched and
pinched, he reasoned, might it simply divide?
Maris is expert in liquid helium, a substance that gives
physicists the perfect opportunity to test this idea because
electrons can exist independently and autonomously within
it. When electrons from a radioactive source are fired into
a vat of helium, repeated interactions with the electrons of
the helium atoms slow them down until, finally, they grind to
a halt. The intruding electrons do not attach themselves to
helium atoms as a third electron, however. The Pauli
exclusion principle makes sure of that, because it forbids
more than two electrons from sharing the same quantum
state. Faced with helium atoms whose electrons have
bagged the lowest energy state-the ground state-an
interloper with no spare energy has no choice but to lodge
in the space between atoms. There it clears a bubble of
space around itself-an electron bubble.
Electron bubbles form only in certain types of liquid-those
in which the van der Waals force of attraction between
atoms is weak enough to allow an electron to push them
apart. In fact only two substances fit the bill: liquid helium
and liquid hydrogen. At very low temperatures in helium,
electron bubbles displace more than 700 helium atoms,
creating a cavity around 38 angstroms (3.8 nanometres)
across. Inside this cavity quantum mechanics rules,
ensuring that the electron can occupy only a limited set of
Maris worked out that an electron in a bubble could be put
into the dumb-bell-shaped excited state by illuminating the
helium with light that had a wavelength of about 10
micrometres, which is easily supplied by a carbon dioxide
laser. In this state, Maris calculated, the electron imparts
most of its force to the ends of the dumb-bell; this force is
enough, he realised, to make the bubble wall wobble
violently. "I found that the force exerted by the electron was
enough to elongate the bubble until it formed a thin neck,"
he says. "If the pressure in the liquid was great enough,
there was the possibility of it pinching off the neck so that
the bubble might actually split in two."
This sounds harmless enough, but the implications are
staggering. If the bubble split, half of the electron's wave
function would be trapped in each of the two daughter
bubbles (see Diagram). As the wave function is the
essence of an electron, the electron would be split into
two. The indivisible would have been divided.
Maris planned to test his idea in the laboratory but first
decided to search back through the literature to see
whether anyone had done the kind of experiments he had
in mind. He soon found what he was looking for. In the late
1960s, Jan Northby and Mike Sanders at the University of
Minnesota studied the speed of electron bubbles moving
in an electric field in liquid helium. They measured the
electric current that flowed as the bubbles moved, and
then illuminated the helium with light. The researchers
expected this to increase the current. They reasoned that
light would eject some of the electrons from the bubbles,
and that these would whiz through the helium, boosting the
current-and that is exactly what they observed.
But as physicists have since realised, this reasoning was
flawed. "We now know that knocked-out electrons form
new electron bubbles," says Maris. "The current should not
have increased." Inexplicably, however, it did. In 1990 and
1992, researchers at Bell Labs in New Jersey ran a
similar experiment, with the same result. No explanation
has ever been found-until now, perhaps.
Maris suggests that, instead of ejecting the electrons, the
light boosted them from the ground state to the
dumb-bell-shaped excited state, and the electron bubbles
split. "There were more bubbles, and being smaller they
were more mobile," says Maris. Although the total charge
in the system remained the same, the smaller bubbles felt
less drag in the helium, and thus moved faster.
"Consequently, the current went up," Maris explains.
Maris believes he has further evidence to support his
explanation. Northby and Sanders saw the increased
current only below 1.7 kelvin, exactly the temperature at
which Maris's theory says the effect should take hold.
According to his calculations, electron bubbles should split
apart only below a critical temperature of 1.7 K. The
crucial factor is viscosity. If it is too great, says Maris, the
liquid will behave like treacle, resisting the elongation of
the bubble and squeezing it back to a sphere. Below
2.19K liquid helium becomes a superfluid: as you cool it,
its viscosity starts to disappear. By 1.7 K, Maris
calculated, the liquid would be so slippery that it couldn't
stop the bubbles dividing.
Other experimenters have studied the mobility of electrons
in a more precise way. They include Gary Ihas and Mike
Sanders at the University of Michigan in 1971 and Van
Eden and McClintock of the University of Lancaster in
1984. These physicists created a short burst of about a
million bubbles which they carefully timed as they moved
through liquid helium in an electric field. Since the bubbles
were created together, they should have crossed the
finishing line together. To the surprise of the
experimenters, most of the bubbles arrived in three
Maris's explanation is again simple. Unlike the electrons
in the Minnesota experiment, these electrons had been
created in an electrical discharge-a miniature bolt of
lightning. This produced light, and Maris says that some of
this light boosted electrons within the bubbles to the
excited state, causing them to split, and split again. Hence
the spread of arrival times, with whole, half and quarter
charges making up most of the current.
McClintock is not yet convinced by Maris. But he admits
that nobody else has come up with a plausible
explanation. "The electrino idea offers a possible way
out," he concedes.
Maris has long realised the furore his ideas would cause.
He spent several years working out the details of electron
bubble fission and gathering experimental evidence
without ever telling anyone what he was thinking. "It took
time to get used to the idea and pluck up the courage to
announce it," he admits. Finally, in June this year, he
decided to go public. He presented his work at a
Minneapolis conference on quantum fluids and solids, and
then published it in a paper in the Journal of Low
Temperature Physics (vol 120, p 173).
The conference organisers thought Maris's work important
enough to give him an extra two-hour session. At the end,
more than 100 physicists questioned every aspect of the
theory. "My first reaction was extreme scepticism, like
everyone else," McClintock says. Maris, though, had an
answer for everything. "He'd obviously thought long and
hard about the whole thing," McClintock concedes.
Maris was encouraged by the response -or lack of it-from
his peers. "I was nervous someone would find a hole," he
admits. "But to my relief nobody dismissed the idea out of
Experts in quantum theory are not so accommodating,
though. "The idea of an electron splitting into fractionally
charged fragments is totally incompatible with quantum
field theory," says Anthony Leggett of the University of
Illinois at Urbana-Champaign. He admits that there could
be something wrong with quantum field theory. "However,
given its overwhelming success in explaining the world,
this is highly unlikely," he says.
According to quantum theory, it is possible to have
strange "superposition states", where the whole electron
exists in both bubbles until a measurement forces it to be
in one or the other. "But we cannot consider states which
have half an electron on each," Leggett insists. It is
impossible to solve the equations of quantum mechanics
with anything other than a whole-charge electron. The
formulations of quantum electrodynamics, the area of
physics that deals with the behaviour and properties of
electrons, don't allow for half electrons, or any other
"If the electron splits and you can measure a fractional
charge, this flies in the face of standard quantum
mechanics as well as high-energy physics," agrees David
Pritchard of the Massachusetts Institute of Technology.
"The idea that the electron is a point particle without
structure is established up to very high energies."
Like Leggett and Pritchard, most physicists are convinced
that Maris's claim falls at the first fence, though they cannot
pinpoint why. Their scepticism is understandable. If Maris
is right then quantum theory is wrong-and nobody has the
slightest idea what they would use to replace it.
Maris being right would have some positive practical
consequences, however. He speculates about building a
device which introduces a partition into a cavity to divide
the wave function of an electron. This could lead to circuits
which exploit the properties of fractionally charged
particles, he says. Half-mass, half-charge electrons might
give electronics a whole new dimension. Then there's the
possibility of a new kind of chemistry. Maybe you could
take an electron bubble out of the liquid, attach the
electron fragment to an atom and do novel chemistry with
fractional electrons. Could this really happen? Maris says
he doesn't know.
The electron fragments, having once been part of the
same electron, might even be "entangled", sharing a
strange telepathic link. Quantum physicists have already
managed to achieve this with photons, and used these
entangled particles of light to perform astonishing feats
such as teleportation and elementary quantum computing.
Fractional charge might add a new string to their bow.
The most profound consequences of splitting the electron,
though, would be on theoretical physics. Maris's only
concrete claim is that an electron's wave function can be
split and mimic a fractional electron. He has no idea of the
full consequences of this-and neither has anyone else.
Maris's hypothesis seems to throw everything we know
about quantum theory into confusion. At the very least, he
believes, his work challenges physicists to be specific
about what they mean by the fuzzy entity that describes
quantum systems. "People are going to have to hone their
ideas of the wave function," he says. "Most importantly,
they are going to have to address the question: what is a
wave function? Is it a real thing, or just a mathematical
Physicists have always been content to think of the wave
function as a mathematical device with observable
consequences. But Maris believes the time has come for
the idea to be grounded in reality. For the electron
bubbles in helium, he says, the size of the bubble is
determined by how much of the wave function is trapped
inside the bubble. If there is no part of the wave function
inside the bubble, the bubble will collapse. "This makes
the wave function seem to be a tangible object," he
Maris remains an experimentalist at heart, though. Since
the theorists have nothing to say about the myriad
questions he has raised, he believes answers won't be
found until there is some more evidence to go on-and that
means doing more experiments. Maris and others, he
believes, are now looking for that evidence. "Already, the
results of my experiments are encouraging," he says.
But Maris also insists that he won't be upset if his idea is
eventually disproved. Having lobbed in his bombshell, he
seems to have decided to sit on the sidelines, enjoying
the ensuing chaos. "What I have come up with is an
intriguing puzzle," he says. "I want people to think. I would
be happy if I was completely wrong but made a lot of
New Scientist issue: 14th October 2000
PLEASE MENTION NEW SCIENTIST AS THE SOURCE
OF THIS STORY AND, IF PUBLISHING ONLINE,
PLEASE CARRY A HYPERLINK TO:
-- -- -- -- --
Eliezer S. Yudkowsky http://intelligence.org/
Research Fellow, Singularity Institute for Artificial Intelligence
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