Wednesday, December 29, 2010

Replication Fall Offs

The replication of experimental results is a fundamental part of the scientific process. If you get some interesting results, someone else should try it too, to make sure what you got wasn't just a fluke. The Truth Wears Off: Is there something wrong with the scientific method? in the New Yorker documents many examples of scientific research in which there was an initial report of significance, followed by a sequence of replication attempts which yielded poor confirmation. Many of these cases were in medicine and psychology, fields in which experimental trials are extremely difficult and expensive.
This really isn't surprising at all. Scientific research is now a major industry. Thousands upon thousands of people are out there racking their brains to come up with new results. Each individual may try and discard dozens or hundreds of ideas before stumbling across something interesting and apparently significant. Now let's imagine a million people around the world are flipping coins every day. On some days, some of the flippers will get a very skewed outcome. A tiny number of people might even get a skewed result several days in a row. But if they keep trying to "replicate" their results, they will eventually find that the significance falls off due to a regression toward the mean. Alas, despite all the training and talent that goes into science, most of the novel ideas researchers try out will not end up being significant. But when thousands of insignificant ideas are tested, a small percentage will end up looking good - initially. Researchers are paid to get results, they will keep trying new ideas until they get a skewed result. But was that result truly significant, or was it just a statistical fluke? There are billions of circuit elements following Ohm's law in the computer I'm typing this with - that's not a statistical fluke. Some scientific results have been tested and replicated an astronomical number of times, especially when they prove useful in technology. But it shouldn't be surprising if difficult experiments - especially involving complicated living organisms - often prove to be disappointing despite some initial promise.
The Journal of Irreproducible Results collects science humor. Some of the examples in the New Yorker article aren't too funny however, especially in the medical field.

Tuesday, December 28, 2010

Human Activity and Fires

Humans cause fires, right? Only You Can Prevent Forest Fires! It might seem that in places and times with less human presence and activity there should be fewer fires. But there is now evidence to the contrary: The Burning Issue in Science reports that evidence from Antarctic ice cores shows declining levels of fire in the Southern Hemisphere until the 1600's, followed by a dramatic peak in the 1800's and now unprecedented low levels of burning.

Sunday, December 26, 2010

Origins of Life at Higher Temperatures

Modern biology depends on an intricate web of chemical reactions, many of which are vastly accelerated by enzymes, which themselves are typically large molecules made by complicated machinery. How did this extraordinary network manage to evolve from a nonliving environment? This paper in PNAS, The Impact of temperature on the time required for the establishment of primordial biochemistry, and for the evolution of enzymes, points out in that many important biochemical reactions proceed much faster in higher temperature environments, which might have been typical in the early earth.

Monday, December 13, 2010


I've been scuba diving at Sipidan in Malaysia for five weeks now. Some of the highlights have included: swimming in the middle of school of 80 bumphead parrotfish, helping my dive guide Niger rescue a sea turtle which had a rope tied to its arms (today), watching two tiny (3 cm) cuttlefish apparently gobbling up even tinier shrimp by shooting out a long thin retractable tentacle out from the midst of their other tentacles (yesterday).
Allister Lee's blog Aquatastic has lots of nice pictures of Sipidan.

Saturday, December 11, 2010

Money Spoils the Fun

People will do some things just for the fun of it. What happens if you provide a financial reward for the same task? The task in this case is to try to press a button exactly 5 seconds after a cue. This study shows that that the financial reward can undermine the appeal of a task people will do for fun: Neural basis of the undermining effect of monetary reward on intrinsic motivation and Removing financial incentives demotivates the brain

Friday, December 10, 2010

Entanglement at High Temperature

Entanglement is one of the most characteristic attributes of "quantum weirdness". Entangled systems are usually microscopic and low temperature. But when the system is not in thermal equilibrium, it should be possible to create entanglement at higher temperatures. Applications may include photosynthesis and perhaps even practical devices some day. See Quantum physics: Hot entanglement in Nature.

Tuesday, December 07, 2010

Is there a problem with Quantum Theory?

Jeremy Bernstein recounts the history of controversies in the interpretation of quantum theory in the preprint Dear Fellow Quantum Mechanics. In particular to we need to take a quantum/probabilistic view of past events as well as future ones? Creepy.