Measurement Shows the Electron's Stubborn Roundness (scientificamerican.com) 103
OneHundredAndTen writes: A new article in Nature reports of a new, extremely precise measurement of the electric dipole moment of the electron. The conclusion is that, within the margin of error of the measurement, the electron remains a perfect sphere. This implies that supersymmetric theories keep running out of corners to hide, that another nail is driven into their coffin, and that string theory looks less and less compelling. By lighting up the molecules with lasers, "the scientists were able to interpret how other subatomic particles alter the distribution of an electron's charge," reports Scientific American. "The symmetrical roundness of the electrons suggested that unseen particles aren't big enough to skew electrons into squashed oblong shapes, or ovals. These findings once again confirm a long-standing physics theory, known as the Standard Model, which describes how particles and forces in the universe behave."
Re:They don't confirm the Standard Model (Score:5, Informative)
I do not think they are claiming anything of the sort. They are saying that, as alternative theories become less likely, there is more reason to believe the Standard Model could be correct.
Re:They don't confirm the Standard Model (Score:4, Insightful)
Re: (Score:1)
You'll just have to go with your GUT on that for now.
It is a theory (Score:5, Informative)
Now if only the Standard Model were an actual theory, instead of a list of empirical observations.
It is a theory that made testable predictions (like the Higgs boson [wikipedia.org]) that were later proven to be correct via experiment. If that's not a theory then nothing is.
Re: (Score:2)
The standard model is...a model, not a theory.
Ah, no, The Standard Model of particle physics is the theory describing three of the four known fundamental forces. [wikipedia.org] Too bad you didn't make the slightest attempt to get a clue WTF you are talking about before farting out onto the internet.
Re: (Score:3, Interesting)
Now if only the Standard Model were an actual theory, instead of a list of empirical observations.
There's plenty of theory behind the Standard Model. It's the core of modern physics. Observed results are explained mathematically, those models make predictions, and the predictions keep being verified. It's a very solid theory.
No one like it, because it's not elegant. There are just too many seemingly arbitrary fields and quantum numbers, and the math is nearly intractable. It's a big stinking mess that keeps successfully predicting all observations.
It's very clear now that string theory has failed a
Re: (Score:3)
Are you saying.. they've been stringing us along? I guess they're at the end of their rope now.
Ughh.. I won't be here all week.
Re: (Score:2)
Perhaps we'd have a better alternative to the Standard Model if decades of brilliant minds weren't wasted chasing string theory nonsense.
I don't mind letting brilliant minds spend decades, and mere billions, trying out an alternative theory of how the universe works. It's still money better spent than the trillions that have been spent over the same period on things with little or no social value.
Re: (Score:2)
All theories are a list of empirical observations that are generalized more or less elegantly, and they all eventually break. Seems like the more elegant a theory is, the sooner it breaks.
Re: (Score:2)
Right, just like General Relatively broke. Oh wait.
Re: (Score:2)
Yes, exactly -- wait.
It will never break on where it works now, it will just be discovered that in some special circumstances the theory no longer predicts correctly.
That said conceivably some postulates and constants on which the theory is based may change over eons -- who is to say they must remain fixed to what they now appear to have been through time -- but in practical terms it will never break for us.
And then, there are exceptions to everything, maybe this particular theory, unlike most others, will
What is proven cannot be unproven (Score:3)
They are saying that, as alternative theories become less likely, there is more reason to believe the Standard Model could be correct.
The Standard Model IS correct. It has been tested and the once a theory is tested the results cannot be unproven. Now it might be that the Standard Model only works for certain conditions or it might be a subset of a more comprehensive theory. Newton's laws of motion very correctly describe large objects moving slowly but the theory was subsumed into Einstein's theory of general relativity. Newton's laws fall out of relativity under certain conditions to a high degree of accuracy and utility. We might
Re: (Score:1)
They are saying that, as alternative theories become less likely, there is more reason to believe the Standard Model could be correct.
The Standard Model IS correct.
Scientific theories can never be proved to be correct. They will agree with experiments, and they will make predictions that are later verified, but that doesn't imply that they are correct. They are useful, that's all. Newton's theory of gravity is (extremely) useful, even if it is known NOT to be correct. The Standard Model is probably similar - it is an extraordinary computational tool, but (maybe) nothing more.
What "Correct" means regarding theories (Score:3)
Scientific theories can never be proved to be correct.
They most certainly can be proven correct and are routinely. You are confused about what being falsifiable means and what being correct means. Being falsifiable means that we can state what data would cause us to declare a theory to be incorrect. It does not mean the theory cannot be proven correct. Correct in the context of a theory means it provides useful predictions. Arguments to the contrary are nothing but philosophical masturbation about whether we really know anything [wikipedia.org] for certain.
To give an exa
Re: (Score:2)
Re: (Score:2)
scientific theories are never "proven" to be correct
Not so, theories are regularly proven to be correct, often by discovering the underlying mechanisms that give rise to the phenomena described by the theory. For example, Gregor Mendel theorized that genes come in pairs and that was later proven by direct observation.
The entire point of experiments (Score:2)
If you want to get really pedantic, scientific theories are never "proven" to be correct, they are only shown to make correct predictions.
A distinction without a difference. Think for half a moment about what the word "correct" really means. The whole point of going out to gather evidence is to prove whether or not the predictions of the theory are correct. You make a prediction and and then you go gather evidence to see it matches your prediction. If the evidence supports the prediction then QED it is a correct model at least for the conditions tested. A theory might only work for some conditions and there might be better models but if
Re: (Score:2)
They most certainly can be proven correct and are routinely.
No theory has ever been proven correct, and they cannot be by definition. They can only be invalidated or not-yet-invalidated-in-known-contexts.
Re: (Score:2)
No theory has ever been proven correct
No random internet pounder could ever be trusted to tell you the truth.
You mean falsifiable (Score:2)
No theory has ever been proven correct, and they cannot be by definition.
Common misconception. You are confused about the fact that all theories are falsifiable but that's NOT the same thing as saying that they cannot be correct. Theories that make testable predictions supported by evidence are by definition correct. Where you argument goes of the rails is that you are confusing what being falsifiable means. All scientific theories are falsifiable, meaning that you can specify the evidence required to prove them false and that you must always be willing to accept such eviden
Re: (Score:1)
Common misconception. You are confused about the fact that all theories are falsifiable but that's NOT the same thing as saying that they cannot be correct
I'm not confused, I'm a scientist. I'm also not some pop-sci hack who believes in absolute truth irregardless to the measurement context.
Re: (Score:1)
Theories are "correct" within some bounds. Within some range of conditions, and to some accuracy, theories can be show to make reliably accurate predictions. The Standard Model just keeps growing those bounds.
Re: (Score:2)
But weren't string theories just supposed to be abstract models of computation rather than a theory that subatomic particles were literally n-dimensional strings? Similarly, even if an electron is measured to be a sphere does not mean it is literally a particle.
Re: (Score:2)
I'm sure the scientist understands the concept.
Does it even make sense? (Score:1)
Does it even make sense to say an electron is "round"? Roundness to me seems to be a decidedly macroscopic idea. At those small scales, all you can really say is that there's something there that has a certain effect on the surrounding particles. But it's not like you can touch it and feel its shape. You can't even tell its exact position and speed (certainly not at the same time). So what does this roundness really mean? Its fields are perfectly symmetrical, maybe?
Re:Does it even make sense? (Score:5, Interesting)
Yes [wikipedia.org].
Huh, + represents negative (Score:2)
That's really intriguing because it allows traditional positive view to be imposed without trying to negate the p.o.v.
I wonder if that has always been the norm for physics.
Re: (Score:1)
That linked Wikipedia page doesn't mention the word "round" anywhere. Do they mean it's a point-shaped dipole? (Which is the only occurrence of the word "shape" in that article).
Calling it "round" brings to mind an image of little tennis balls which electrons, as far as I understood, are not.
Re:Does it even make sense? (Score:4, Insightful)
It does mention the word "sphere" 13 times though. The words "Cube" or "Pyramid" are not present either.
Re: (Score:1)
I still don't see the link with electrons, though. The spheres in that article are macroscopic examples. None of that seems to apply to electrons, nor suggest they have some sort of shape.
Anyway, after some googling I found that they are not actually talking about the shape of the electron itself (which is a point particle as far as we know) but the cloud of virtual particles around it. Here's the link [stackexchange.com].
Little tennis balls (Score:5, Funny)
Everyone always wants to talk about the little tennis balls, but no one ever talks about the tiny little golden retrievers chasing them around.
Re: (Score:2)
Alright, to be less glib, electron is a constituent-less particle (an elementary particle). It doesn't make technical sense to talk about any shape at all, because if it had shape, that would imply it's not an elementary particle (and with the exception of string theory—which I do not well know and am contemptuous of—all theories beyond the Standard Model treat the electron as being an elementary particle).
Even so, the electric dipole moment of an electron is a way to describe "non-roundness" t
Re: (Score:2, Informative)
The part that's "round" is the electric dipole moment, not the electron. The electron's charge is perfectly uniform with spherical symmetry, i.e., "round".
That means the electron can't be made up of smaller particles, or spontaneously decay into particles which quickly re-combine into an electron, or any other sort of hidden complexity, as that would reveal itself in a lack of roundness: a non-zero EDM.
Re: (Score:2)
This is a robotic response to any post with "Well, actually" in it.
Re:Does it even make sense? (Score:5, Insightful)
Re: (Score:2)
If I understand correctly (I am not a particle physicist), describing an electron as a point is orthogonal to the idea of particles having both particle-like and wave-like behavior. That is, when physicists say it's a point, they're not saying it's a particle and not a wave, they're saying it has no dimension, unlike particles such as neutrons and protons, which have a diameter. Somehow (and I admit I do not understand how this is possible) electrons do not have any size - thus they are a point.
Re:Does it even make sense? (Score:4, Informative)
Bingo. You answered the apparent contradiction yourself.
Electrons are point-like particles -- meaning they're so small as to not have a well defined size if any. You describe the electron density for the orbitals of electrons -- which can be many shapes. That's more about the probability of where to find an electron in relation to the type of atom or the molecular bond between atoms.
This article is about the magnetic moment of the electron. So, if an electron were in a known position, this experiment shows that it doesn't matter from what direction in 3-D space another particle approaches this hypothetical electron, it will still get the exact same response. So, the field force-lines around the electron are perfectly spherical in strength.
This was important because electrons have a magnetic moment (like a bar magnet) that we call spin -- either spin up or spin down... which you're likely familiar with in chemistry as the rule that 2 electrons can share the same orbital as long as they are opposite spins. Some alternate theories propose that this means some parts of the electron are more charged than others or that the shape was more like a spinning charged ring instead of a sphere.
We've long known that nothing is actually spinning to create "spin." It's just a label for a quantum property that was somewhat useful as an analogy long ago. Yet, there remains this strange source of angular momentum. This experiment just confirmed that even though there is a magnetic dipole moment, that property doesn't mean the particle itself is distorted in order to express the property.
What's even weirder is that "spin" being a quantum property, is in a strange superposition state until measured and the spin axis can change depending upon the experiment.... with no intermediary direction for the spin. It's a binary choice -- spin up or spin down for any axis tested.... and seemingly random.
TL,DR -- this test just showed that the particle we call an electron is the same when approached from all angles - same charge, same interaction. So, it's "spherical" even though it's point-like. The probability distribution of an electron's location in atomic orbitals or molecular bonds is a different subject.
Re: (Score:1)
Re: (Score:2)
That is a great explanation. Thank you.
Re: (Score:2)
There are still a lot of questions on how the standard model actually works. String Theory was made to try to explain the results they see, however if you apply such theory there are aspects that are expected to happen which may be able to observe. If such aspects are found the theory is stronger, if they are absent then the theory is weaken, and perhaps may need to be altered, or even tossed out.
Real Science is all about observing and measuring. The theoretical stuff is just the first part of the process
One-Electron (Score:2)
Well, if electrons are so perfect, that only makes me wonder is Feynman's One-Electron postulate is actually true....
Re: (Score:2)
because it was not Feynman who postulated it?
Re: (Score:2)
As the proverb says (Score:2)
Re: (Score:2)
Supersymmetry? Really? (Score:3)
Re: (Score:2)
By no means an expert, but I though string theory was essentially some sort of extension of super symmetry.
Re: (Score:2)
My favorite line in Contact is during the first party where Drumlin is saying, "i just think grant money should be spent for the benefit of The People."
Nerdy young physicist: "Not unlike my L-band globular clusters."
Re: (Score:3)
Super symmetry is technically a standalone idea, but super string theory, which is the modern version of string theory, includes super symmetry as a pretty essential part.
Re: (Score:3)
Re: (Score:2)
Not Supersymmetry, T-Violation (Score:2)
I'm trying to think of the last time an experiment to try to prove supersymmetry actually worked
None ever have which is why we are still looking for it since it is still one of the most promising theories to explain both why the Higgs is so low in mass and what Dark Matter is. However, this result really has nothing to do with Supersymmetry. Discovering an electric dipole moment for an electron would be an example of time reversal (T) violation (as the paper says in its abstract).
Supersymmetry does not require any new T-violation. While it is possible for SUSY to include new T-violation not includ
Re: (Score:2)
Supersymmetry has been added to String Theory, they call it SuperStrings. It is postulating there are more massive partners to particles we see in the particle zoo. However, the LHC has failed to detect any supersymmetric partners. So the S. Theorists adjust their parameters to make the supersymmetric partners more massive so they can hide from the LHC. Think of it as a physicist's version of the G-d of the Gaps that we get from the Intelligent Design folks. Those supersymmetic partners are devilish little
Re: (Score:2)
You make it all sound sinister. Supersymmetry has a range of masses, depending on the precise version. Currently, LHC's inability to find evidence of supersymmetrical partners at its current energy levels would appear to falsify some versions of supersymmetry, but not all. That being said, what I've read from some supersymmetry researchers seems to suggest that they are getting a bit worried, as what are viewed as the strongest supersymmetry contenders may already have to be abandoned. At the same time, pre
Re: (Score:2)
even string theory is more plausible than supersymmetry
Just like Scientology believes in Xenu, I was under the impression that String Theory's hidden ultimate idea is that God is a Cat. It that not right?
The Gist of TFA (Score:2, Informative)
The abstract:
"The standard model of particle physics accurately describes all particle physics measurements made so far in the laboratory. However, it is unable to answer many questions that arise from cosmological observations, such as the nature of dark matter and why matter dominates over antimatter throughout the Universe. Theories that contain particles and interactions beyond the standard model, such as models that incorporate supersymmetry, may explain these phenomena. Such particles appear in the va
Re: (Score:2)
I tried to type a response, but didn't have time.
Re: (Score:2)
Re: (Score:3)
Good question. I found this helpful: https://www.quora.com/How-does-refraction-work-If-a-photon-interacts-with-matter-it-is-absorbed-but-it-passes-through-a-transparent-material-Therefore-it-is-not-absorbed-therefore-it-does-not-interact-So-what-happens-to-slow-the-speed-of/ [quora.com]
How can it be a sphere anyway? (Score:2)
According to quantum theory its a probability volume which is not necessarily round depending on the enviroment.
Re: (Score:1)
Re: (Score:2)
Several parts of quantum theory have proven useful. Like Plank's quantum theory and its applications on the photoelectric effect (which was in fact Einstein's first paper). These have lead to things like solar panels and LED lights becoming possible. Dirac's work has also had several applications. Other parts have had mixed success. I think the most controversial parts are things like Heisenberg's work.
Re: (Score:2)
Circular logic? (Score:2)
Ever heard of a ball of string?
(Probably a rounding error anyway)
"perfect" sphere (Score:2)
Interesting point (Score:2)
They have falsified many forms of string theory. Specifically, all forms requiring supersymmetry to squash the electron.
This shows superstrings can be falsified.
It also falsifies many other extensions to the standard model.
This is interesting as it shows you can falsify categories of solutions, which may help physics advance more rapidly.
90% confidece? (Score:2)
That is kind of a large gap to trot around stating you have determined a constraint, no?
topological question (Score:2)
Strings are 1D and this is a test in 3D - don't we expect to see an electron in 3D space? The 1D projection would be a point plus a radius ... if I recall correctly.
Maybe the equations say something else?
This is why I keep my electrons in a box (Score:2)
Then you can't tell if they're round, or if they're square, man.
It's the Hufflepuff Electron Uncertainty Principle.
Of course, they escape when you open the box, and it takes forever to catch them again.
The Standard Model is known to be incomplete (Score:2)