Best of Science 2005

At the Relativistic Heavy Ion Collider (RHIC) on Long Island, the four large detector groups agreed on a consensus interpretation of several year’s worth of high-energy ion collisions: the fireball made in these collisions -- a physical model of the primordial universe only a few microseconds after the Big Bang -- is a liquid of strongly interacting quarks and gluons (PNU 728).

This story of the top physics experiment of 2005 chosen by the American Institute of Physics is revealing about the nature of modern physics research.

First, let’s look at the science. In the RHIC accelerator two beams of gold ions beam along with energy of up to 100 GeV 9100 billion electron volts) then meet in a head-on collision event. The total collision energy is 40 TeV (40 trillion electron volts). Of this, typically 25 TeV serves as a stock of surplus energy---call it a fireball---out of which new particles can be created. The outward streaming particles provide evidence for determining the properties of the model Big Bang fireball.

This is an example of what could be called BIG physics. It requires large amounts of money and lots of scientists and technicians. In fact budget woes forced the cancellation of two major US physics experiments just as researchers were about to start. In one case the DOE nixed the BTeV experiment, a $140 million experiment that would have run at the Fermi National Accelerator Laboratory in Batavia, Illinois. Using beams from Fermilab's Tevatron collider, BTeV would have studied bottom quarks, the heavier, unstable cousins of the down quarks (presumably) found in protons and neutrons.

Another thing to note is the philosophical nature of the enterprise. It takes a sizable leap of faith to conclude that the experimental fireball replicates what happened ten microseconds after the Big Bang. The so called “Standard Models” of the universe and of particle physics are so well established that few realize the degree of uncertainty in these theories.

Related to that orthodoxy is the politics of the physics establishment. Note that physics now proceeds by “consensus.” It’s the same consensus that denies telescope time to astronomers who have a different view of the origin. But that is another story.

SCIENCE, the premier magazine in the greater world of science, just published the list of the top scientific breakthroughs of 2005. I was surprised to find that the winner was Evolution. That’s right -- the theory developed by Charles Darwin a century and a half ago was named the breakthrough of 2005. Today evolution is the foundation of all biology, so basic and all-pervasive that scientists sometimes take its importance for granted. So what exactly is the “breakthrough?”

One of the most dramatic results was genome mapping of our closest relative, the chimpanzee. The genome data confirm our close kinship with chimps: We differ by only about 1% in the nucleotide bases that can be aligned between our two species, not including a chunk of noncoding material bringing the total difference in DNA between our two species to about 4%.

2005 was also a standout year for researchers studying the emergence of a new species when a single, contiguous population splits in two. For example, European Blackcap bird populations seem to be splitting up as ever more of these warblers migrate to northern grounds in the winter rather than heading south. Isotopic data revealed that northerly migrants reach the common breeding ground earlier and mate with one another before southerly migrants arrive. This difference in timing may one day drive the two populations to become two species. It’s not exactly a “missing link” but it’s not chopped liver either.

Evolutionary breakthroughs are not just ivory-tower exercises as they hold promise for improving human well-being. Take the chimpanzee genome. While humans are susceptible to AIDS, coronary heart disease, and malignant malarial infections, chimps aren't. Studying the differences between our species will help pin down the genetic aspects of many such diseases.

It’s all very nice, but “breakthrough” of the year? The journal's editor in chief, Don Kennedy, said SCIENCE picked evolution as the year's biggest breakthrough in part because it was a hot topic, but stressed there was a wealth of research that justified the choice. He wrote: "Ironically, also this year, some segments of American society fought to dilute the teaching of even the basic facts of evolution," a reference to the rise of the theory of Intelligent Design, which holds that some aspects of nature are so complex that they must be the work of an unnamed creator rather than the result of random natural selection. Could science be so politicized? Ya think??