Swans on Tea

It also comes with great current times potential difference.

Click the cartoon to go to XKCD and see the hover tag.

Rhett analyzes a football collision. Momentum and Football

Bookends for physics geeks

We said that it’s simple, and it is: it’s a brick wrapped in a piece of paper.
If you don’t have a couple of bricks (and we didn’t), they turn out to be cheap at hardware and home improvement stores. These are “cement bricks” — red dyed cement– and cost about $0.25 each. Wrapping them up keeps them from scratching up your shelves and books, but also from depositing cement debris everywhere.

The geek part is on the outside.

Quaternion Julia Fractals

The definition of a Julia set can get a bit complicated, but it can be thought of as an object that carves up four-dimensional space into two categories – belonging to the set, and not belonging to the set. How exactly the shape is carved depends on some very deep mathematics.

The Onion: NFL Scientists Postulate Theoretical Down Before First Down

Citing the extremely low level of entropy present before a normal set of football downs, scientists from the NFL’s quantum mechanics and cosmology laboratories spoke Monday of a theoretical proto-down before the first.

“You can say that again” — The King of Id

My molar has apparently abdicated — it rejected its crown. Ugh. Fortunately I was able to have the dentist see me and fix my little problem.

An assassination attempt, with emphasis on ass: the bomb was concealed in the orifice of choice for concealing items. I’d say convenient orifice, but it’s probably not all that convenient.

The bomb couldn’t be that big, and water (being a large fraction of the human body) isn’t very good shrapnel.

While the assassination proved unsuccessful, AQAP had been able to shift the operational paradigm in a manner that allowed them to achieve tactical surprise. The surprise was complete and the Saudis did not see the attack coming — the operation could have succeeded had it been better executed.

We know this wasn’t The Onion because there is no remark about how hindsight is 20-20, mention of a thorough probe of the incident, or talk of a push for new security measures. Or discussion of market penetration of security technology. (Oh, strike that last one. They say it here)

Via Schneier, who cautions us not to tell the TSA.

I don’t generally watch the teen-coming-of-age drama shows, unless forced (as I was on vacation; the episode of Degrassi was a cheap ripoff of Pump Up the Volume without the benefit of a topless shot of Samantha Mathis), but I’m sure this plot has been covered somewhere: Awkward Teen asks the Beautiful Cheerleader to the prom; she has recently split with Handsome Quarterback, but doesn’t immediately say yes to AT, so he assumes she will say no and asks Safety Date, who is much more likely to want to go with him, and she says yes. Immediately thereafter, BC also says yes. Depending on the context, either tremendous angst or hilarity ensues. Possibly both, depending on the quality of the writing.

How does this apply to me? A while back I got an invitation from an old navy buddy to give the keynote talk at the Southern Atlantic Coast Section of the American Association of Physics Teachers Conference. Keynote speakers are typically either famous, to some degree, within either the physics or pop-physics communities, or are attempting to become so by promoting a book, so I am not the Beautiful Cheerleader in this scenario. I figured this was an act of desperation, but I agreed, thinking it would be fun. Lo and behold, it turns out that the other speaker can make it. (Cut to commercial)

All is not lost. I’m getting my own slot during the conference, though that will be a tad awkward — the after-dinner talk (and the public talk that some conferences have) has more leeway in not being directly related to the theme of the conference. I don’t have any particular insight into teaching to share; certainly not an hour’s worth. Same goes for a lot of themes that show up here — I don’t want to make the mistake of trying to turn a 5-minute skit into a feature movie, because it rarely works (are you listening, Saturday Night Live?) So I’ll go with my plan and talk about clocks and timekeeping, with a few cartoons thrown in, and leave the connection to teaching as an exercise for the interested viewer. I was going to do a bit about how I’m at least a little bit famous, and promote the blog, and I may leave that in.

I was also toying with the idea of going with a minimalist presentation, with very few slides in the first part of the talk. The show-and-tell part, though, really needs the “show” as much as the “tell.” Still working on that. I lose the comfort of the “1 – 1.5 minutes per slide” guideline, and since talks will follow mine, there’s pressure to finish on time.

Throwies are simple LED circuits — the LED and a battery, with an optional magnet so they will stick to ferromagnetic materials.

Evil Mad Scientist Laboratories does a pretty exhaustive analysis on the circuits, looking at battery life and potential danger of these simple circuits. Some thoughts on throwies

This data shows a couple of interesting things. First is that the power-law model seems to hold fairly well. Second, the power function that pops out is not very different from that of the data from only the first half hour– integrating both out to 24 hours gives two answers– 150 mAh and 186 mAh –that differ by only 25%. The estimate based on the long data record (150 mAh) is the more accurate one, but this does suggest that we should be able to use the data from the first half hour alone to get a fairly good “factor of two” estimate of the performance over 24 hours.

(Wired) Reader Photo Gallery: Awesome DIY Astronomy

Entanglement in the Macro World

By linking the electrical currents of two superconductors large enough to be seen with the naked eye, researchers have extended the domain of observable quantum effects. Billions of flowing electrons in the superconductors can collectively exhibit a weird quantum property called entanglement, usually confined to the realm of tiny particles, scientists report in the Sept. 24 Nature.

That sounds pretty cool, though they don’t go into any details about why exposing the currents to microwaves would entangle them. If the microwaves were linearly polarized, and the current loops are acting as antennae, I can see this; linear polarization can be expressed as a superposition of right- and left-circular polarization, so that might do the trick.

However, I have some objections to the reporting.

After interacting in a certain way, objects become mysteriously linked, or entangled, so that what happens to one seems to affect the fate of the other.

This is ambiguous, so I’m not sure if it fall into the trap of the “doing something to one changes the other” error, but even ambiguous is bad. Entanglement means knowing the state of one tells you the state of the other. And the real kicker here is “mysteriously,” which implies that nobody knows what the heck is going on. There are unanswered questions in entanglement, as there are in all areas of science, but it’s not the same as scientists fumbling and bumbling around, saying, “OMG! WTF?” Entanglement is a prediction of quantum mechanics, and the fact that people are exploiting it shows that it’s not really Sphinx-y (terribly mysterious) at all. Physics ain’t easy, but there’s no need to hamstring the understanding of it by selling it as mysterious.

In the new study, researchers used a microwave pulse to attempt to entangle the electrical currents of the two superconductors. If the currents were quantum-mechanically linked, one current would flow clockwise at the time of measurement (assigned a value of 0), while the other would flow counterclockwise when measured (assigned a value of 1), Martinis says. On the other hand, the currents’ directions would be completely independent of each other if everyday, classical physics were at work.

This can’t be right. If they are independent of each other you expect the currents to have no correlation, so half the time they should be in the opposite direction — so simply measuring currents in the opposite direction is not an indication that they are entangled. That could hold only if classically you always expected them to be in the same direction. The indication that they are entangled is the much higher incidence of finding the opposite currents, as was observed.

STUDY: U.S. subsidises fossil fuels 2.5 times more than renewables

Fossil fuels were given about $72 billion during the seven years, while renewable fuels got just $29 billion. The money the U.S. spends on renewables isn’t all that great, either. Of the $29 billion, $16.8 billion went to producing corn-based ethanol. Just two tax credits – the Foreign Tax Credit and the Credit for Production of Nonconventional Fuels – account for about $30 billion.

To be fair, normalized to the amount of energy, renewables probably win, but this still seems backwards. Weaning ourselves from foreign oil and reducing CO2 emissions isn’t going to be painless. I think it’s time that we recognize that, stop being like children afraid of getting a shot at the doctor’s office, and suck it up a little bit.