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Splitting the electron.

By Rand Race in MLP
Fri Jan 26, 2001 at 03:31:23 PM EST
Tags: Science (all tags)
Science

An article at the New Scientist covers the contention of British physicist Humphrey Maris that electrons may be divisible.


Maris proposes that a lone electron embedded in a superfluid (liquid helium in this case) can be split by illuminating it with a 10 micrometer beam from a CO2 laser if the temperature and pressure of the medium are just right. Although Maris' contention is purely theoretical at the moment, evidence that supports the theory has surfaced in a series of experiments done in the late sixties that, until now, produced results that have never been theoretically explained.

If Maris' theory proves true then quantum physics will have to be rebuilt from scratch. The implications for electrical engineering would be profound as well.

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Splitting the electron. | 9 comments (7 topical, 2 editorial, 0 hidden)
Two comments (3.66 / 3) (#2)
by DesiredUsername on Fri Jan 26, 2001 at 01:21:56 PM EST

First let me say I'm no physicist.

That said, how would this be revolutionary? I thought we already knew electrons were divisible--that's what all this talk of quarks and superstrings is about, isn't it?

There is one thing I'm skeptical about, though: the use of lasers to split an electron. Ummmm...lasers are just photons...the "l" stands for "light". Using a whole "laser-full" of photons is surely overkill. And splitting an electron with a photon sounds like a pretty chancy business.

Play 囲碁
Electrons aren't divisible (as far as we know) (3.00 / 2) (#3)
by Flavio on Fri Jan 26, 2001 at 01:32:20 PM EST

Electons are leptons. Leptons aren't quarks. Leptons live by themselves and don't bind to make larger particles as quarks do.

I'm also skeptical about using pure energy to split electrons precisely because we're actually splitting their wave functions. We usually learn that electrons are _by definition_ indivisible, so we'd only get a stream of energy back when the electron settled down to its lower energy state.

Flavio

[ Parent ]
physicists (4.33 / 3) (#4)
by ana on Fri Jan 26, 2001 at 01:36:14 PM EST

Well, I am a physicist...

That said, how would this be revolutionary? I thought we already knew electrons were divisible--that's what all this talk of quarks and superstrings is about, isn't it?

Umm, no. The quarks go together to make up heavy particles like neutrons and protons. As far as we know, electrons are indivisible. Quantum Electrodynamics, mentioned in the article as being a very successful theory, can predict the magnetic properties of the electron to an accuracy of one part in a hundred billion (11 significant digits); it's gotta be doing something right.

And they're just using the laser (actually a maser, so sue them) to excite the electron in the bubble into a quantum state which is dumbell shaped. A single, very low energy, photon interacts with one electron. You use a laserfull of them so it happens fairly often.

My take on this is the quantum one mentioned at the end: it's not fractional electrons, it's a peculiar quantum effect where you don't know which of the sub-bubbles has the electron in it until you do an experiment to find out. If you find the electron in one of them, the other one will be empty, every time.

But it's an interesting story. Further work (i.e. experiments) can nail down some of this stuff.

Ana

Years go by; will I still be waiting
for somebody else to understand?
--Tori Amos

[ Parent ]

Sounds like 1 and 0 (none / 0) (#9)
by turtleshadow on Sat Jan 27, 2001 at 12:22:10 AM EST

Unfortunate all that quantum physic stuff isn't soon to be harvested to define and store value states like 1 or 0. perhaps thats why I'd better stick to software.
Turtleshadow

[ Parent ]
The article is confusing in some parts (4.00 / 4) (#5)
by Flavio on Fri Jan 26, 2001 at 01:37:19 PM EST

I'm referring specially to the part about the 1960's experiment:

"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."

How can light eject eletrons from bubbles? They mean eject eletrons from helium atoms.

And they carry on to say:

"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."

And why exactly not? I can't see any flawed reasoning. Nothing forbids bubbles from moving in the "perfect fluid" that is liquid helium. Therefore, they have more moving bubbles than before and a larger current than before.

Does anyone have any ideas on how to interpret this?

Flavio

endemic problem (none / 0) (#8)
by ana on Fri Jan 26, 2001 at 05:16:50 PM EST

It's often nearly impossible to figure out what's going on from science stories in the media; this is a good example. It's not at all clear from what's there why the current should do what it does in the one model but not the other.

So I wonder--Since, every time I know something about a news story from other sources, it contains mistakes or distortions (or, in this case, dumbing down to the point that it's not true any more), why do I trust the media to tell me about things I don't know about?

Ana

Years go by; will I still be waiting
for somebody else to understand?
--Tori Amos

[ Parent ]

Probability waves vs. "Bubbles" (4.14 / 7) (#7)
by HiRes on Fri Jan 26, 2001 at 02:24:36 PM EST

I am a physicist, but this topic is out of my particular field...

This appears to be the crucial point, buried near the end of the article:

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 argues.

The current popular interpretation of the electron (or any other particle) wavefunction --at least, the way I learned it -- is as a "probability wave", whose squared amplitude gives you the probability that the particle will be found at that place upon measurement. Basically what it seems Maris is proposing is that the wavefunction is more "real" (for lack of a better word) than that, and can be split up by carefully choosing and tweaking its surroundings.

If his claims prove true, then it ought to be possible to chop the electron into any fractional bits you like, simply by exciting it into higher energy states which would assume more exotic spatial distributions, then "squeezing" the bits apart as before.

On the other hand, the skeptic in me believes the notion is an application of a flawed interpretation of the nature of the wavefunction. I think Maris realizes this though, and it seems to be a no-risk position to take. In other words, "Hey, everyone thinks this is what the wavefunction really is, but what if it isn't -- not that I'm making any claims, mind you?"

Now, I'm no low-temp guy and I don't understand the specific physics involved, so I could be way off base. But that's the way it looks to me.
--
wcb
wait! before you rate, read.

Splitting the electron. | 9 comments (7 topical, 2 editorial, 0 hidden)
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