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Researchers At Brown University Shattered a Quantum Wave Function

blueg3 Actual abstract (139 comments)

"An electron in liquid helium forces open a cavity referred as an electron bubble. These objects have been studied in many past experiments. It has been discovered that under certain conditions other negatively charged objects can be produced but the nature of these “exotic ions” is not understood. We have made a series of experiments to measure the mobility of these objects, and have detected at least 18 ions with different mobility. We also find strong evidence that in addition to these objects there are ions present which have a continuous distribution of mobility. We then describe experiments in which we attempt to produce exotic ions by optically exciting an electron bubble to a higher energy quantum state. To within the sensitivity of the experiment, we have not been able to detect any exotic ions produced as a result of this process. We discuss three possible explanations for the exotic ions, namely impurities, negative helium ions, and fission of the electron wave function. Each of these explanations has difficulties but as far as we can see, of the three, fission is the only plausible explanation of the results which have been obtained."

Research group website
Non-paywalled copy of paper

TLDR: This research group studies exotic electron effects in superfluid helium. They see a particular effect that is not currently explained. There are a few possible explanations, and they argue that a particular one is probably true.

Inaccurate "news" articles ensue.

(The physics is subtle enough that, despite reading the abstract and bits of the paper, I would not venture to try to summarize it. You can smell a mile away, though, that this article is poor understanding mixed with hyperbole. The specific flavor is, "Quantum Mechanics is Philosophical Magic".)

yesterday
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Black Swan Author: Genetically Modified Organisms Risk Global Ruin

blueg3 Re:Nonsense. Again. (403 comments)

requires massive amounts of pesticides to live

Since when is this true of any organism?

because your dog Sniffles is actually the product of genesplicing of a dog and fish genes

At the breeding level, no, your dog is the product of many generations of selective inbreeding, to the point that most purebred dogs have serious genetic defects and health problems. But your dog does undoubtedly have quite a bit of DNA from other species. Retroviruses are helpful like that.

2 days ago
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Soda Pop Damages Your Cells' Telomeres

blueg3 Re:'Regardless of... income and education level' ? (422 comments)

They generally don't know that it's an organic process without controlling for those factors. You can't shove a microscope up someone's ass and just observe why a particular diet is having a particular effect.

Remember how people always like to harp on how correlation is not causation? Well, it's said too often and too zealously, but it's still true. One of the most important lessons is that you need to control for confounding factors, or the effect you observe could simply be a correlation. It's very, very hard to control for the entire set of a human's behavior, though -- which is what you'd want to do in a classic, traditional experiment.

There are a handful of confounding factors that are constantly problems -- they correlate with tons of things. Any good study about humans will control for them. Income and education level are two of them. So you will always see a paper controlling for these and, if they find an interesting effect, you will see a statement about how the effect is independent of income and education level -- because if that wasn't true, it's not a very valuable finding.

about two weeks ago
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Password Security: Why the Horse Battery Staple Is Not Correct

blueg3 Re: Objection One: (549 comments)

I wasn't disagreeing with you. (Weird, for the Internet, I know.) I was just answering your semi-rhetorical question of "how would they think of random words"? The answer is that they can't.

If you want some disagreement: while picking spots in a dictionary is random, it's not a uniform distribution and it's not as random as you might suspect. It's much safer to use a mechanical method that your brain has as little control over as possible to do the selection: dice, for example.

about two weeks ago
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Password Security: Why the Horse Battery Staple Is Not Correct

blueg3 Re:Objection One: (549 comments)

Humans can't think of random words. There's not a sufficiently random process available. Humans can think of semi-random arbitrary words, which are totally different.

about two weeks ago
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FBI Says It Will Hire No One Who Lies About Illegal Downloading

blueg3 Re:Fewer candidates to draw from... (580 comments)

"Seeding" is simply the mode BitTorrent is in when you no longer have any parts of the file that still need to be downloaded. Prior to that, even though you are not "seeding" yet, you are still transmitting the pieces that you *have* downloaded to any peers that ask for them.

That's sort of the whole idea behind BitTorrent: peers trade pieces of partially-downloaded files with one another to reduce demand on seeders.

about three weeks ago
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FBI Says It Will Hire No One Who Lies About Illegal Downloading

blueg3 Re:Fewer candidates to draw from... (580 comments)

Technically you could turn off all uploading, and hence not be distributing....

True, though most BitTorrent clients don't support this.

about three weeks ago
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Physicists Observe the Majorana Fermion, Which Is Its Own Antiparticle

blueg3 Re:Fermion that is its own antiparticle (99 comments)

Particles are interesting bundles of localized energy present in particular fields that happen to have a particular set of properties.

Quasiparticles are interesting bundles of localized energy present in particular fields that happen to have properties similar to particles and also happen to be describable in terms of collective effects of what we call "particles".

Particles simply aren't as "fundamental" as you seem to think they are.

about a month ago
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Physicists Observe the Majorana Fermion, Which Is Its Own Antiparticle

blueg3 Re:Fermion that is its own antiparticle (99 comments)

Perhaps you think it's uninteresting because you mistakenly think that there's some deep, fundamental difference between a particle and a quasi-particle that makes one "real" and the other "not real".

about a month ago
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Physicists Observe the Majorana Fermion, Which Is Its Own Antiparticle

blueg3 Re:Fermion that is its own antiparticle (99 comments)

That's hard to answer for a few reasons. I'm not a particle physicist, the subject is kind of complicated, and most people start off ill-informed (sorry!).

Antiparticles are not particularly weird and particle-antiparticle interactions are, in particular, not some kind of physical witchcraft. I always have disliked that it's called annihilation. At the subatomic level, particle interactions are common and they generally involve the "creation" and "destruction" of particles. For example, maybe a neutron decays into a proton, an electron, and an electron antineutrino (by way of one of its down quarks changing into an up quark). Particle interactions are all sort of a shuffling of energy between the different flavors of bundles of energy we call particles. Lots of different physical quantities, like charge, are conserved, limiting what interactions can happen.

In the interest of simplicity, a lot of what I'll say next is slightly wrong.

Antiparticles aren't particularly weird. Particles all have a set of physical properties. It turns out that for each particle, there is another particle that is basically exactly the same, except all these physical properties are opposite. So an electron has charge -1 and an antielectron (positron) has charge +1. In fact, if you look at a legal particle interaction and replace all of the particles with their antiparticles, it's still a legal particle interaction.

An implication of this is that if a particle and its antiparticle interact (not a particle and *any* antiparticle, but *its* antiparticle), the net total for any of their conserved quantities (like charge) is zero. That means the major legal interaction is that the two particles are destroy and produce photons. While photons are particles, we tend to think of them as just energy, so the particle-antiparticle interaction is an "annihilation": two particles go in, energy and zero particles come out.

The "its antiparticle" bit is important. You don't see a lot of antielectrons because a free antielectron would easily encounter an electron and annihilate. But there are plenty of antineutrinos because they interact weakly with the rest of the world. An antineutrino interacting with, say, a proton does not cause annihilation. Even an antielectron interacting with, say, a proton doesn't do anything special.

Oh, also, it turns out that, at least for the "normal matter" particles like electrons and protons, the universe seems to contain pretty much only the normal-matter particles and (relatively) no antiparticles. There doesn't seem to be any reason, in physics, for one to be preferred over the other. (It's just that in one region of space, you couldn't have a mixture and also have stable matter.) So that's weird.

This is all a long-winded way of getting to the answer that particles that are their own antiparticles aren't particularly exciting. They all have the property that conserved quantities (at least, those that are negated in antiparticles) are zero. So they all naturally have annihilation interactions: when two collide, they can annihilate and form protons. But the annihilation interaction isn't particularly dramatic or weird, it just sounds interesting. The particles all probably also have interactions with all sorts of other types of particles, too, and it really comes down to what particle it happens to collide with first. Maybe a photon and an antineutrino interact with a proton and form a neutron.

Most of the particles that are their own antiparticles are relatively neutral to normal matter (and consequently, also to normal antimatter). But they're all a very different kind of particle from normal matter. They're things like force-carriers (photons) and muons, and they interact with electrons and protons differently from how electrons and protons interact with each other.

For some real fun, look up Feynman diagrams, a neat way of writing down different legal particle interactions. One axis is space (in one dimension) and one axis is time. Now, any 90-degree rotation of a legal interaction is still a legal interaction.

about a month ago
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Physicists Observe the Majorana Fermion, Which Is Its Own Antiparticle

blueg3 Fermion that is its own antiparticle (99 comments)

The summary (and the article!) imply that it is rare and strange for a particle to be its own antiparticle. This is not the case. Plenty of boson and mesons are their own antiparticles: photons, gluons, pions, etc. This isn't a particularly weird situation.

However, fermions are another story. Fermions and bosons are the two kinds of fundamental particles. They behave very differently. While there are bosons that are their own antiparticle, there are no known fermions that have this property. All the fermions we know of are Dirac-type. It's been long postulated that there could be Majorana-type fermions, which, among other things, are their own antiparticles.

It's interesting, but not quite as crazy as implied.

about a month ago
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Obama Administration Argues For Backdoors In Personal Electronics

blueg3 Re:Before the digital age ... (575 comments)

Before the digital age, they seized physical documents, which were usually trivial to access (with a warrant) and decipher.

about a month ago
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iOS Trojan Targets Hong Kong Protestors

blueg3 Re:Attention Slashdot Editors (72 comments)

It doesn't just require a jailbreak. It also requires the user to install the software.

about a month ago
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David Cameron Says Brits Should Be Taught Imperial Measures

blueg3 Re:Idiot (942 comments)

I think it also tends to be much faster, for the same reason. Add ingredient, zero, add ingredient, zero, etc. You can tear through measuring a complicated set of ingredients in no time.

I tend to use grams unless the recipe actually specifies weight in US customary or if there is some particular motivation for using lb/oz. (Brewing supplies here, for example, are all sold by the pound or ounce, so it's useful to stick with those units.

about a month ago
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David Cameron Says Brits Should Be Taught Imperial Measures

blueg3 Re:Idiot (942 comments)

Right. This is specifying the recipe by weight, though. It's just specifying it by relative weights, using a very convenient custom unit system.

about a month ago
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David Cameron Says Brits Should Be Taught Imperial Measures

blueg3 Re:Size of a cup (942 comments)

Weren't "words with multiple meanings" like "mile" exactly what crashed that Mars lander?

The Mars Climate Orbiter was never intended to land, but it did.

And no. It had nothing to do with words with multiple meanings. Nobody in the US in engineering (or science, really) should be confused about what pound-seconds are. (This is despite the fact that both "pound" and "second" have multiple definitions.) What crashed the Mars Climate Orbiter is that the spec for a piece of software required that it produce results with one unit, and it instead produced results with a second unit. That's going to be a problem, regardless of whether the incorrect unit it produces is kN-s, dyn-s, lbf-s, cm-g/s, or kg-km/hr. (And if you think that scientists and engineers who use metric always use the SI base unit, you clearly don't do science or engineering.)

about a month ago
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David Cameron Says Brits Should Be Taught Imperial Measures

blueg3 Re:Size of a cup (942 comments)

Now you're misstating the precision of the measurement and using units that aren't necessarily marked on the measuring devices. (Dry-measure cups are not often not graduated.)

The ambiguity doesn't really exist. People are either being intentionally difficult or users of the metric system are too stupid to handle words with multiple meanings.

about a month ago
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David Cameron Says Brits Should Be Taught Imperial Measures

blueg3 Re:Idiot (942 comments)

Note that they are actually measuring by weight, using a custom unit system.

about a month ago
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David Cameron Says Brits Should Be Taught Imperial Measures

blueg3 Re:Idiot (942 comments)

Basically, no, the kitchen is exactly the place I want metric measurement

You are confusing two issues: metric vs. US customary units, and measurement by volume vs. by mass.

I assure you that both metric and US customary unit systems have units for volume and mass, so you can measure either way using either system. It's also the case that neither unit system specifies how one is to measure ingredients in the kitchen.

It is European convention to measure many kitchen dry ingredients by weight. It is, unfortunately, US convention to measure many dry ingredients by volume. This is okay, even convenient, for some things where the real quantity doesn't particularly matter. (While cherry tomatoes will vary, you could probably use twice as much or half as much without any trouble.) For precision measurements, you need to use weight. This is what's used by professional cooks in the US already and is becoming increasingly common in cookbooks.

Incidentally, if you buy your butter in sticks, it's easy to measure a cup of butter. Otherwise, it's convenient to post a list of standard densities for things like butter.

about a month ago
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David Cameron Says Brits Should Be Taught Imperial Measures

blueg3 Re:Idiot (942 comments)

While cup is a standard and precise unit of measurement, there are lots of materials in cooking you should not measure by volume (whether that volume is in cups or mL).

about a month ago

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