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Comment: Re:'Regardless of... income and education level' ? (Score 4, Informative) 419

by blueg3 (#48182123) Attached to: Soda Pop Damages Your Cells' Telomeres

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.

Comment: Re: Objection One: (Score 1) 546

by blueg3 (#48141803) Attached to: Password Security: Why the Horse Battery Staple Is Not Correct

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.

Comment: Re:Fewer candidates to draw from... (Score 1) 578

by blueg3 (#48117591) Attached to: FBI Says It Will Hire No One Who Lies About Illegal Downloading

"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.

Comment: Re:Fermion that is its own antiparticle (Score 1) 99

by blueg3 (#48060907) Attached to: Physicists Observe the Majorana Fermion, Which Is Its Own Antiparticle

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.

Comment: Re:Fermion that is its own antiparticle (Score 4, Informative) 99

by blueg3 (#48057495) Attached to: Physicists Observe the Majorana Fermion, Which Is Its Own Antiparticle

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.

Comment: Fermion that is its own antiparticle (Score 5, Informative) 99

by blueg3 (#48056389) Attached to: Physicists Observe the Majorana Fermion, Which Is Its Own Antiparticle

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.

Comment: Re:Idiot (Score 1) 942

by blueg3 (#48039097) Attached to: David Cameron Says Brits Should Be Taught Imperial Measures

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.

Comment: Re:Size of a cup (Score 1) 942

by blueg3 (#48039033) Attached to: David Cameron Says Brits Should Be Taught Imperial Measures

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.)

Comment: Re:Size of a cup (Score 1) 942

by blueg3 (#48036843) Attached to: David Cameron Says Brits Should Be Taught Imperial Measures

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.

My idea of roughing it turning the air conditioner too low.