the zero body problem

Posted on: Fri, 10/29/2010 - 18:01 By: Tom Swiss

"It might be noted here, for the benefit of those interested in exact solutions, that there is an alternative formulation of the many-body problem, i.e., how many bodies are required before we have a problem? G.E. Brown points out that this can be answered by a look at history. In eighteenth-century Newtonian mechanics, the three-body problem was insoluble. With the birth of general relativity around 1910 and quantum electrodynamics in 1930, the two- and one-body problems became insoluble. And within modern quantum field theory, the problem of zero bodies (vacuum) is insoluble. So, if we are out after exact solutions, no bodies at all is already too many!" -- Richard D. Mattuck, A Guide to Feynman Diagrams in the Many-Body Problem

did we say 2012? would you believe...2062? Or 2112? Or 1962?

Posted on: Tue, 10/19/2010 - 11:05 By: Tom Swiss

If I haven't stated it clearly before, let me do so here: the disaster hype around 2012 is a bunch of muddleheaded nonsense. The Mayans themselves didn't believe that some great disaster was due when their "long count" calendar wraps around; it was just time for a big party, same way 2000 was for us.

And no, there will not be some grand alignment with the center of the galaxy on December 21, 2012: the Milky Way is too blobby for the idea of a visual center to be meaningful, and the winter-solstice sun will never actually eclipse the galaxy's central black hole (which shows up as a point-like radio source) -- it doesn't even make its closest alignment in the sky with that black hole for another 200 years, not that this means anything anyway.

So there's no big deal in 2012. seems that maybe the Mayan calendar doesn't actually wrap around in 2012 after all. A new review of the conversion of the ancient Mayan calendar to our Gregorian one suggests that it may be off by as much as 50 to 100 years. Gerardo Aldana, associate professor at UC Santa Barbara, looked at the arguments anthropologist Floyd Lounsbury made in support of the so-called "GMT constant", and found them wanting, throwing the conversion into doubt.

So it might not wrap around until decades from now -- or it might have already happened decades ago. (Rather than taking this as a debunking, I'll bet that at least one 2012 disaster entrepreneur will try to take advantage of this when the world fails to end in 2012, and start hyping some other date for the apocalypse.)

Now, some folks think that 2012 is a convenient time to think about making a change -- just as with a New Year's resolution, there's actually nothing special about January 1, just a social convention. Fine, great, and wonderful: just don't assign unwarranted supernaturalism to the date.

Me, I'll be turning 42 in 2012, and as a big Hitchhiker's Guide to the Galaxy fan that means more to me than any old Mayan calendar. Also, 2012 fits the Law of Fives: 2 + 0 + 1 + 2 = 5, so as a Discordian it's significant. But Mayan prophecy? Astronomical disaster scenarios? Poppycock.

Newton the Alchemist

Posted on: Wed, 10/13/2010 - 21:57 By: Tom Swiss

You may know that Issac Newton is a contender for the greatest physicist of all time. You may know that he invented calculus to amuse himself. But did you know he was a serious alchemist? Natalie Angier discusses Newton's fascination with alchemy in The Hindu.

How did one of the greatest scientists of all time get caught up in what is usually thought of today as superstition? She cites William Newman, a professor of the history and philosophy of science at Indiana University in Bloomington, who has extensively studied Newton's alchemical work. "Alchemy was synonymous with chemistry," says Newman, "and chemistry was much bigger than transmutation."

signs of the apocalypse: accidental death rays and monkey security forces

Posted on: Tue, 10/05/2010 - 18:11 By: Tom Swiss

Two signs that the End Times are surely nigh:

  • The new Vdara hotel in Vegas has a problem with its pool. It's not the chlorine balance or a leak: it's an accidental death ray. The glass skyscraper is focusing sunlight to a degree that's burning people and has melted plastic. The "solar convergence phenomenon" was taken into account when the hotel was designed, and owner MGM Mirage hired a consultant -- who placed a filter over the window, reducing the effect by 70 percent, apparently not enough. (Imagine if this filter were to be removed, bwah-ha-ha.)
  • The upcoming Commonwealth Games in Delhi also have a problem: monkeys. Rhesus macaques often cause property damage and occasionally attack people (they were indirectly responsible for the death of Delhi's Deputy Mayor S.S. Bajwa), but are protected by devout Hindus. Delhi has decided that the solution to monkey problems is more monkeys; in a scene that could be part of the next remake of Planet of the Apes, officials are deploying langurs, a larger species of monkey, to keep the macaques at bay.

    (Yes, I know monkeys aren't apes.)

more evidence that meat-heavy diets kill

Posted on: Sat, 09/11/2010 - 10:40 By: Tom Swiss

New research published in the Annals of Internal Medicine uses data from the Nurses' Health Study and the Health Professionals' Follow-up Study to compare the overall mortality effects -- i.e., how likely something is to help you to your death -- of two different sort of low-carb diets: those based on animal products, and those based on plant foods.

Unsurprisingly, overall low-carb diets were associated with an increase in overall mortality. But what's interesting is that when they broke it down by plant-based versus animal-based diets, people consuming animal-based low-carb diets had higher mortality overall and also from cardiovascular disease and cancer, while vegetable-based low-carb diets were actually associated with lower all-cause and cardiovascular disease mortality.

Bjorn Lomborg and other climate "skeptics" who have come to their senses

Posted on: Wed, 09/01/2010 - 23:09 By: Tom Swiss

Bjorn Lomborg was one of the first high-profile "climate change skeptics". In 2001, he argued in his book The Skeptical Environmentalist that fighting global warming would be a waste of money.

Now, in a new book Smart Solutions to Climate Change, Lomborg is calling climate change "undoubtedly one of the chief concerns facing the world today", and calling for a carbon tax to collect $50 billion a year.

The Week has a brief on him and five other climate "skeptics" who have come around.

saturated fat blocks leptin and insulin, and is addictive

Posted on: Tue, 08/24/2010 - 18:40 By: Tom Swiss

Scientific American reports on research showing that a diet high in saturated fat causes the brain to become resistant to leptin and insulin, hormones that let us know when our need for food has been fulfilled.

The research in question was done on rats, and it's always tricky to extrapolate such work to humans; and there are serious ethical issues with killing rats to find our why humans become such pigs when they eat cows. But the phenomenon in question is expected to apply to humans as well.

The researchers also performed in vitro experiments where they directly observed palmitic acid (a common saturated fatty acid) inhibiting the signaling of nerve cells exposed to insulin.

On the other hand, oleic acid, a monounsaturated fatty acid, did not produce this result.

What evolutionary mechanism might produce such a result, that too much fat in the system actually tells the body to increase rather than decrease food uptake? Here's what one leptin expert quoted in the SciAm article says:

getting root -- square root, that is

Posted on: Tue, 08/24/2010 - 11:56 By: Tom Swiss

If you're a bit of a math geek, you may know Newton's method for finding the square root of a number. It's fairly simple; you start with a guess, divide the number by the guess, and take the average of the quotient and the guess as a new guess. (Remember, to take the average of two numbers, we add them and divide by two.) Lather, rinse, repeat, and you'll get closer and closer the the root.

For example, let's say I want to find the square root of 110 -- which is going to be close to 10, but let's say I don't know that, so I pick 55 as my guess. 110/55=2, so my next guess is (55+2)/2=28.5. Getting closer already.

110/28.5 is 3.8596 (we'll say four places is enough), so our next guess is (28.5+3.8596)/2=16.1798.

110/16.1798 is 6.7986, so our next guess is (16.1798+6.7986)/2=11.4892.

110/11.4892 is 9.5742, so our next guess is (11.4892+9.5742)/2=10.5317.

Let's do one more round: 110/10.5317=10.4447, (10.5317+10.4447)/2=10.4882

You can see that we're getting close and closer to the real value, which is around 10.4881, and that we could repeat this over and over to get as close as we want.

That's pretty cool, but you can't easily use this to get a specific number of digits of accuracy in the result. Plus, you have to keep doing division. Yuck. I used a calculator (actually, bc, the Unix desktop calculator) above, but what if we were doing this by hand?

I've had this trace of memory stuck in the back of my head for about thirty years, that I once saw a method for computing square roots digit-by-digit, that looked something like long division. And finally, thanks to Google, I found it again!

Shelley and science

Posted on: Wed, 08/04/2010 - 20:16 By: Tom Swiss

In honor of the birthday of Percy Bysshe Shelley, here's a fascinating article I just stumbled upon about his attitude toward science:

From the days at Eton however when the embryo poet set trees on fire with gunpowder and a burning glass, or "raised the devil" -- and his tutor -- with electric batteries; even from earlier days, when he brought stained hands and singed clothing to the nursery at Field Place and tried to "shock" his little sisters into a cure for chilblains; Shelley's great interest lay in chemical and physical experiments that gave free scope to fancy and were too primitive to call for the exactness alien to the romantic nature of the experimenter.

During his short stint at Oxford, Shelley wrote:

"What a mighty instrument would electricity be in the hands of him who knew how to wield it? What will not an extraordinary combination of troughs of colossal magnitude, a well arranged system of hundreds of metallic plates, effect? The balloon has not yet received the perfection of which it is surely capable; the art of navigating the air is in its first and most helpless infancy. It promises prodigious facilities for locomotion, and will enable us to traverse vast tracts with ease and rapidity, and to explore unknown countries without difficulty. Why are we still so ignorant of the interior of Africa ? -- why do we not despatch intrepid aeronauts to cross it in every direction, and to survey the whole peninsula in a few weeks?"

Ah, Shelley: nonviolent anarchist, atheist, vegetarian, poet, worshiper of Pan and fan of the Goddess, and now lover of technology when applied for humane ends. Is there anything you did that I don't love?

risibly bad nutrition studies

Posted on: Tue, 08/03/2010 - 23:38 By: Tom Swiss

Reuters is reporting on a study that claims to show that low-carb diets can have an advantage over low-fat ones for heart health. I'm sure that fans of Atkins-style diets, the folks who want to believe that bacon is a health food, will be touting the results. (If you actually read the article, you'll see that the small differences in HDL levels and blood pressure are no big deal, but I doubt that will stop low-carb fans from latching on to the headline.)

What this study actually shows, however, is just how utterly bad some nutrition research can be.

What was this "low-fat" diet like? The supposed low-fat diet had a target of 55 percent of calories from carbs, 15 percent from protein and 30 percent from fat.

But 30 percent of calories from fat is not a low-fat diet. The 30% recommendation was based on what was seen as an achievable goal in a fat-addicted culture, not as a health optimum; it's like, "hey, can you cut the cigarettes down to a pack a day?"

The average intake is estimated at 35.4% calories from fat in industrialized nations, so 30% is only a little below that. (I've seen estimates that the American average is 45%, but that only shows how fat-addicted we are, not that 30% is low.) In developing nations it's 19.6% -- close to the 20% estimated for Late Paleolithic humans. That's much higher than other primates, and almost certainly well in excess of our needs, but we might call 20% a moderate-fat diet. An actual low-fat diet like the Ornish plan gets around 10% of its calories from fat.

Considering 30% to be a "low-fat" diet is an all-too-common flaw in diet studies. But this one addds another big whopper. Where did the low fat, high carb diet get its carbs? Were those on this arm of the study getting complex carbs from vegetables and whole grains? Well, no: study participants

were instructed to start exercising regularly -- mostly brisk walking -- and learned tactics for weight management, such as writing down what they ate every day and setting reasonable short-term goals (if you normally eat 10 candy bars a week, for instance, first try cutting out a couple rather than going cold-turkey.)

(Emphasis added.) So it seems sugar was on the menu, even in high amounts.

Meanwhile, the low-carb group got their small ration of carbs from a strictly regimented selection of vegetables, fruits, grains, and dairy.

So the "low-fat" diet here was a high-fat, sugar-laden, nutritional nightmare, and the "low-carb" one was an even higher-fat, sugar-free nutritional nightmare. It's not surprising that the low-carb diet, bad as it is, might look good in comparison -- even with the side effects this study found common: hair loss, bad breath, and constipation.

And this passes for science?

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