The Vacuum is an Interesting Place

Vacuum has friction from an effect similar to the casimir effect

The phenomenon of vacuum friction for spinning objects is somewhat different than for the static parallel plates: the accelerating charges in a spinning conductive object interact with the vacuum fluctuations and can emit photons.

A quick scan of the paper (pdf) indicates that the thermally radiated photons have a different net angular momentum than the ones absorbed from the reservoir, i.e. the effect is that the emitted light has a net polarization which carries off the angular momentum as the particle slows down.

The Non-Physics of Rockets

Space Stasis: What the strange persistence of rockets can teach us about innovation.

The development of rockets — driven by war and the invention of nuclear weapons, and the relationship the story has with recent economics and innovation.

The above circumstances provide a remarkable example of path dependency. Had these contingencies not obtained, rockets with orbital capability would not have been developed so soon, and when modern societies became interested in launching things into space they might have looked for completely different ways of doing so.

Before dismissing the above story as an aberration, consider that the modern petroleum industry is a direct outgrowth of the practice of going out in wooden, wind-driven ships to hunt sperm whales with hand-hurled spears and then boiling their heads to make lamp fuel.

That's Infralife!

The Virtuosi: Life in the Infrared

Modified-webcam pictures.

[I]f we get an object hot enough, it will glow visibly. However, warm objects (say, humans, cars, tanks) while not emitting enough visible light to glow, will emit easily detectable infrared light. This makes infrared imaging a handy technology for finding warm things in the dark. And, since many opaque things in the visible are transparent in the infrared (or vice versa), you can dream up a lot of fun to be had if you could only see in the infrared.

Not only fun, but also easy, and I know because I’ve done it, too.

Q & A

I mention from time to time that this blog is hosted by Science Forums (dot net), which is a discussion board for science, mainly, and because I don’t teach anymore, I spend a lot of my time answering physics questions or discussing/debunking topics that are posted (or moved) to our “Speculations” forum, where threads on “alternative” science live. The kinds of threads can generally be divided into two categories: those that ask a question, and those that try and tell you the answer. The latter is pretty exclusively the domain of the crackpot; they have “found” the answer to some corner of science, and want to tell the world. They are predictable, even to the point of being able to play bingo with the tenor of their responses. The path they take depends on what flavor of crackpot they happen to be. (For example, to me a crank is the subset of the crackpot species who gets angry at being contradicted. They will yell at you when you tell them they are wrong, and then complain about being persecuted. Just like Galileo was.)

The former — the askers — do share a few characteristics of the crackpot, though, namely a lack of familiarity with the process of science, because most of the people that originate threads fall somewhere on the spectrum of being amateurs or nonscientists. This makes the process is very Gumpian — when a question is posted, you don’t know what you’re gonna get in terms of physics background, and more importantly, you don’t know what you have in terms of scientific literacy (facts, concepts and/or science process). This makes for some interesting dynamics. As I recently observed, the act of correcting someone’s misconception is often considered rude in a social setting (or so I’m told. I’m a geek and have no social skills) but it’s de rigueur as science. There’s no shame attached to blurting out a wrong idea and having it shot down; it’s what we’re trained to do — both the blurting and the shooting. Let as many smart people as you can try and find a flaw, see if you can fix any problems, and what survives is probably worthwhile. But an outsider may not have developed a thick enough skin to be comfortable with this.

Another issue that arises is the lack of appreciation of the history of science, or the appearance of science as dogma. The person who wonders why their wonderful idea for perpetual motion won’t work may not be satisfied with “it violates the first and/or second law of thermodynamics.” If one does not have an awareness of the history and the process, one might not appreciate the enormous weight of the statement. There is no dogma behind the laws, but unless you’ve sat through a semester of thermodynamics, you might not see this. Worse than this, there are sites on the intertubes that propose and support a panoply of wacky —and demonstrably wrong — concepts, and you have people who think that finding a site that agrees with them makes them right. There’s no a priori reason to accept one source over another when you don’t understand the concept. Ignoring Sturgeon’s Law — that 90% of everything is crud — is dangerous when drinking from the internet.

A third issue is the problem of jumping into the deep end, or biting off more than you can chew, or some other metaphor for not having properly learned the basics. A lay person might read about quantum entanglement and want to learn more about it, but as much as one would wish to study it, at the end of the day it’s advanced quantum mechanics. Analogies can only go so far, and quite often the curious one will try and construct a model of what’s going on, and be hampered by the lack of a physics foundation. The model almost instantly fails because some common misconceptions persist, which might have been driven out in a semester or two of classroom instruction, and science discussion boards, like blogs, aren’t the best method of that kind of information transfer — the kind of high-volume, strongly-interacting information transfer that the classroom tends to be (or to which it aspires). It’s like someone showing up one day to some upper-level class without having taken the prerequisite course; not understanding the basics (or the math) is a huge impediment. Sadly, another trait shared by the eager amateur and the crackpot is often a disdain for math.

But one thing I must note is where the amateur differs from the crackpot: while the amateur is simply unaware of the volume of evidence that is behind a brief debunking of their toy model or a seemingly dogmatic statement, the crackpot, by positing that he knows “the truth,” is making a de facto assertion that this evidence either doesn’t exist or is all wrong. That’s a huge difference.

So it’s tough to figure out the right response to questions and often the difficulty has little to do with the physics, but I do it because I enjoy it. (Blogging is somewhat different, in that SFN is directed toward interaction, while a blog is somewhat more “preachy,” in the sense that a response is not integral to the process.) The payoff is that sometimes you get asked really good questions, and you are working with people who really want an answer; most of them work at developing an understanding even when the topic is over their head (though occasionally you do uncover the attitude of “this should be easy” and blame you when they don’t instantly understand the intimate details of relativity). The questions that come from those not constrained by what’s been taught in a classroom give me the occasional idea for a post as well.

A Bar Walks Into a Physicist

… oops, wrong reference frame.

I mentioned Brian Malow, the science comedian, in one of my Science Online 2011 summary posts. Here he is discussing (bad) science in Star Wars. Yes, you probably know the scene, and it has nothing to do with who shot first.

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and some X walks into a bar jokes, some of which you already know

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He Ain't Heavy

Uncertain Principles: Heavy Heavy Water

So is it plausible that barrels of heavy water might’ve sunk, while barrels that contained ordinary water floated?

One thing not considered, or another way of looking at the problem: given the conditions of February in Norway, what if the heavy water had already frozen inside the full barrel. Would heavy ice float? It has a density of 1.0177 g/cm^3 (vs 0.917 for regular frozen water) and freezes/melts at 3.82 °C. Water has a maximum density of 1.0 g/cm^3. Even not inside of a metal barrel it would definitely sink, if it were 100% D2O. If the barrel were 10 kg, then we could suffer 50g/L of “missing” deuterium, which is roughly 50% “heavy.” More if the barrel were slightly more massive. 200 L of regular ice would give displace up to an extra (1000-917)*0.2 = 16.6 kg of water, meaning it could support 36.5 lbs of metal at neutral buoyancy. I thing we’re still in “plausible but not proven” territory.

Just Passing Through

What is a Neutrino…And Why Do They Matter?

Brief summary of neutrinos. There’s a strange quote at the end, though, which bothers me more than the “give off puffs of energy” tucked into the explanation.

“If 100 years ago, I told someone that the universe was filled with massless, chargeless particles with no energy, I wonder if they’d have believed you,” Conway said

I’m not believing you now. The article just got done saying that neutrinos aren’t massless, and how do they have no energy? I wonder of the quote was mangled or is out of context.
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Hägar the not-so-Horrible Physicist

Did Vikings navigate by polarized light?

The saga describes how, during cloudy, snowy weather, King Olaf consulted Sigurd on the location of the Sun. To check Sigurd’s answer, Olaf “grabbed a sunstone, looked at the sky and saw from where the light came, from which he guessed the position of the invisible Sun”2. In 1967, Thorkild Ramskou, a Danish archaeologist, suggested that this stone could have been a polarizing crystal such as Icelandic spar, a transparent form of calcite, which is common in Scandinavia2.