That River in Egypt

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You Are Not So Smart

You Are Not So Smart is a blog devoted to self delusion and irrational thinking.

There’s a lot of research out there suggesting you have no idea why you act or think the way you do.

It feels awful to accept such things, so you create narratives to explain your own feelings and behavior.

On the Dunning-Kruger Effect

Have you ever wondered why people with advanced degrees in climate science or biology don’t get online and debate global warming or evolution? Yet, people without a degree in psychology will write 1,200 words about a psychological bias.

The less you know about a subject, the less you believe there is to know in total. Only once you have some experience do you start to recognize the breadth and depth you have yet to plunder.

Cap and Trade

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The Virtuosi: My Pepsi* Challenge

The basement of the Physics building has a Pepsi machine. Over the course of two semesters Alemi and I have deposited roughly the equivalent of the GDP of, say, Monaco to this very same Pepsi machine (see left, with most of Landau and Lifshitz to scale). It just so happens that Pepsi is now having a contest, called “Caps for Caps,” in which it is possible to win a baseball hat. There are several nice things about this contest. Firstly, I drink a lot of soda. Secondly, I like baseball hats. So far so good. Lastly (and most important for this post), is that it is fairly straightforward to calculate the statistics of winning (or at least simulate them).

On the surface this is a lesson in basic statistics and simulations. But the other lesson here is that physics graduate students have been conditioned to not value their time paricularly highly.

Magic Magic

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I’m confounded by magic.

Radioactive isotope of tin confirmed to have doubly magic nucleus

Magic proton or neutron numbers give the nucleus greater stability and stronger binding, and are therefore usually more common than nuclei with unfilled orbital shells. In doubly magic nuclei both proton and neutron shells are filled, leading to even stronger binding and stability. The outer shells of doubly magic nuclei are rigidly spherical.

OK, here’s an instance where someone is using inconsistent and/or confusing terminology. If magic numbers refer to filled shells, then Sn-132, having 50 protons and 82 neutrons, is doubly-magic by definition. The only thing you have to confirm is that it’s Sn-132. The Tin isotope whips out its ID card, and you’re done.

But no, apparently that’s not enough.

Other confirmed doubly magic nuclei include helium-4, oxygen-16, lead-208, calcium-49, and nickel-48, which are abundant and stable, and nickel-56, which was discovered in 1998 and is less stable than the others, having a half-life of just 5.9 days. Tin-132 is even more unstable with a half-life of only four seconds, which has made confirmation of its doubly magic nature difficult. It has 50 protons and 82 neutrons, and is the first confirmed doubly magic isotope that is both neutron-rich and radioactive.

The scientists investigating this seem to already know it has magic numbers of both, but that doesn’t confirm the doubly-magic nature of the isotope. They had to verify that it is spherical as well, by looking at Sn-133 and saw that it behaved as expected of having a single excess neutron (I assume in terms of a quadrupole moment). But if it hadn’t, would the nucleus still be doubly-magic? Or would it be that the model of doubly-magic nuclei was wrong? I think it’s the latter; magic numbers refer to the numbers (hence the name), and models of nuclear shape are something separate.

On a related note, I wonder if anyone is looking at Sn-100, which is also doubly-magic (using my definition). It’s listed on the table of nuclides as having a half-life of 0.94 seconds, which implies it’s been made in the lab and studied to some extent. Then again, the table of nuclides lists Sn-132 has having a half-life of 39.7 seconds, which is an order of magnitude longer than what’s given in the article. So I’m thoroughly confused. But as a Gemini, I never know what to expect.

Survivor Skills

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This may prove useful in in the event you absolutely must open a bottle of wine but have no corkscrew.

How to open a wine bottle with a shoe.

Technically a shoe and a wall. My French is pretty much limited* to Je ne parle pas Français (and croissant, so I would never say Je ne parle pas croissant) so I assume the narrator is telling you that pressure is force/area, and so any force you exert on the liquid at the base by whacking the bottom of the bottle will result in a much larger force being transmitted to the cork owing to the reduction in area.

What he is probably not telling you is that this is a poor technique for ketchup, and not because French cuisine and ketchup are incompatible or that it won’t work on screw tops (both true) but that ketchup is a non-Newtonian fluid, and when the ketchup clogs the neck of the bottle it prevents air from entering, which is necessary to let the ketchup flow. Don’t invert and bang on the bottom (this holds true for more than ketchup, but I digress). Hold it with the open end down at 45º and tap the neck to induce the shear-thinning.

(*My limited vocabulary also allows me to get the following joke: Why do French omelettes have only one egg? Because in France one egg is un oeuf.)

Violating the Violation

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Cosmic Variance: Marketing CP Violation

Sean discusses the recent CP violation results, and how they were reported.

The point is that the conclusion doesn’t hold — not everything about CP violation is necessarily related to baryogenesis. We don’t know how baryogenesis actually happened — there are many theories on the market, and any of them or none of them may be right. Therefore, there’s no way of knowing whether any particular manifestation of CP violation is in any way related to baryogenesis. There could be lots of different ways in which CP is violated. In particular, there’s no compelling theoretical reason why the CP violation being studied in the decays of B mesons has anything at all to do with baryogenesis. It’s possible — lots of things are possible. But what’s being studied isn’t baryogenesis; it’s CP violation.

Mea culpa. Ten 3-loop Feynman diagrams as penance.

Pick Your Poison

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Harmful Drinks in America

(Update: link dead. Try this one instead, seems to be the same list)

The 20 worst drinks, along with a food equivalent.

5. Worst Frozen Fruit Drink
Krispy Kreme Lemon Sherbet Chiller (20 fl oz)

980 calories
40 g fat (36 g saturated)
115 g sugars

Sugar Equivalent: 16 medium-size chocolate eclairs

Imagine taking a regular can of soda, pouring in 18 extra teaspoons of sugar, and then swirling in half a cup of heavy cream. Nutritionally speaking, that’s exactly what this is, which is how it manages to marry nearly 2 days’ worth of saturated fat with enough sugar to leave you with a serious sucrose hangover. Do your heart a favor and avoid any of Krispy Kreme’s “Kremey” beverages. The basic Chillers aren’t the safest of sippables either, but they’ll save you up to 880 calories.

Don't Drop any Mentos in it

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The Strangest Disaster of the 20th Century.

A recounting of the Lake Nyos CO2 eruption in Camaroon.

There is a physical limit to how much CO2 water can absorb, even under the tremendous pressured that exist at the bottom of a 690 foot deep lake. As the bottom layers become saturated, the CO2 is pushed up to where the pressure is low enough for it to start coming out of solution. At this point any little disturbance—a landslide, stormy weather, or even high winds or just a cold snap—can cause the CO2 to begin bubbling to the surface. And when the bubbles start rising, they can cause a siphoning or “chimney” effect, triggering a chain reaction that in one giant upheaval can cause the lake to disgorge CO2 that has been accumulating in the lake for decades.