While calling NASA’s “manned” space flight programs (such as [the International] Space Station) worthless with regards to science, Steven Weinberg calls NASA’s “unmanned” space flight programs (such as Martian robots Spirit and Opportunity robots and Hubble Telescope) very important to the advancement of science.

Steven Weinberg stated at the Tuesday, September 18, 2007 Science Writers’ Workshop called “Dark Energy: A Decade of Discovery and Mystery” at the Space Telescope Science Institute [home of the Hubble Space Telescope] in Baltimore, Maryland, U.S.A., “The International Space Station is an orbital turkey. No important science has come out of it. I could almost say no science has come out of it. And I would go beyond that and say that the whole manned spaceflight program, which is so enormously expensive, has produced nothing of scientific value.”

(From Nobel Laureate Weinberg calls space station an “orbital turkey”)

Allen Mills/UC Riverside

Dance of death

By soaking a silica sponge with antimatter, physicists have made the first matter-antimatter molecules. With further refinement, the technique might be used to briefly condense antimatter into fluid or solid states or even to create the first gamma-ray laser.

About 10 years ago, researchers created atoms of antihydrogen by combining antiprotons and positrons, the antimatter equivalents of protons and electrons. By itself, antihydrogen is as stable as hydrogen, though it’s difficult to store in our matter world because of antimatter’s propensity to vanish in a flash of gamma rays as soon as it comes into contact with matter.

For more than 50 years, however, physicists have been able to create nucleus-free “atoms” consisting of one electron and one positron. Attracted by their opposite charges, electrons and positrons will orbit each other, as the stars in a binary system do.

Unlike antihydrogen, however this unusual matter-antimatter hybrid, called positronium, is unstable. It enjoys just a brief dance of death as the two particles spiral in toward mutual annihilation.

(Read the rest of my article Alliance of Opposites, freely available on the Science News Web site)

Making the world flat

The economies of poor and developing countries often depend almost exclusively on a single product—perhaps timber or coffee—or on a handful of products at most. That’s hardly a startling observation, but what’s puzzled economists over the years is why it’s been so difficult for these countries to start up new activities in the hope of spurring economic growth and lifting themselves out of poverty.

While there have been a few success stories, such efforts have often ended up consuming heaps of money to little lasting effect.

A team of economists and physicists [led by network theory expert Albert-László Barabási and by former Venezuelan Minister of the Economy Ricardo Hausman] is now proposing a new way to look at development. The researchers have shown that a country’s competitive edge can spread from one kind of product to another along a well-defined network of links, much as disease epidemics tend to spread among people who are socially connected.

The newly charted map of products could help countries design good policies by indicating the most promising paths to creating new industries. The network’s structure also presages the hurdles that many developing countries will face along that path.

(more…)

Everything was ready for the celebratory feast. Weeks earlier, the alien fleet had entered Earth’s orbit and made radio contact, and now the visitors would receive their official welcome. Dozens of heads of state would greet humanity’s guests during an official dinner at the White House.

The aliens looked remarkably similar to us—apart from their green scales, that is. Moreover, the chemistry of their bodies and of ours was also very similar, scientists from the two worlds had concluded. Sure, the alien cells produced molecules not found in human biochemistry, but the building blocks of those molecules were essentially the same carbon-based amino acids and sugars as the ones in our bodies.

But on the eve of the great meeting, the science adviser to the President burst into the Oval Office. “The dinner must be called off, or the aliens might die!” the adviser told the startled President. “We forgot to check their chirality!”

Photo Researchers, Inc.

WHAT’S WRONG WITH THIS PICTURE? (See illustrations at the end of this post for the answer)

That’s a word that few politicians—indeed, few people outside science—will know. But chirality, or handedness, is an essential characteristic of the molecules of life. Most naturally occurring organic molecules are chiral, meaning that they are distinct from their mirror images in the same way that our right and left hands differ.

In the lab, chemical reactions that synthesize amino acids and sugars create the right- and left-handed versions of the molecules in equal amounts. Life on Earth, however, uses one version almost exclusively, preferring what are conventionally called right-handed sugars and left-handed amino acids. A molecular preference for only one handedness is what chemists call homochirality.

In principle, organisms could exist that use both kinds of molecules or that exclusively adopt the opposite forms from those used in life on Earth. This is what troubled the scientists in the alien state dinner scenario: Just as our bodies can’t absorb organic matter of the wrong handedness, so too the aliens might find our food equally indigestible—and perhaps even toxic.

Most scientists believe that Earth life’s choice of chemical handedness was purely random. “The most plausible idea is that it was an accident,” says biochemist David Deamer of the University of California, Santa Cruz. It’s possible, then, that the chemistry of some alien forms of carbon-based life—assuming such things exist—may well have the opposite chirality to ours. We might find alien pizza even harder to digest than deep-dish.

On the other hand, a few scientists say that something more fundamental might be going on. They argue that throughout the universe, nature might consistently choose one handedness over the other. That intrinsic preference, these scientists suggest, might originate from the influence of the weak nuclear force, the only fundamental force of nature that can tell left from right. In recent years, a number of experiments have provided tentative—if controversial—support for this proposal.

(more…)

Just when the universe had barely begun to get us used to a new level of weirdness — what with the pervasiveness of dark energy, the anti-gravitational push that wasn’t even on the map until ten years ago — here comes a new discovery that seems to contradict even the little we thought we knew.

NASA/CXC/M.Weiss

Even dark matter isn’t what it used to be

The weirdness in this case is that of dark energy’s lugubrious pal, dark matter.

Last year, astrophysicists reported remarkable evidence for the existence of dark matter by observing the results of the collision of two clusters of galaxies, collectively known as the bullet cluster. (See Dark Matter Really Exists, the article I wrote about what I declared my favorite science story of 2006.)

In the bullet cluster, the collision had taken the clusters apart. While the intergalactic gas from the two clusters had bungled up together, the galaxies themselves had sped through each other, apparently unaffected. The galaxies’ halos of dark matter in that case had kept traveling along with the galaxies themselves. Dark matter is invisible, but its presence was revealed by how it curved space around itself, squeezing the images of galaxies in the background.

Dark matter has never been caught in the lab, and its nature is largely unknown. The fact that it has never been detected means that it tends to zip through ordinary matter without interacting. In the bullet cluster, scientists saw evidence that dark matter particles from one cluster also did not interact with those from the other cluster.

While the clouds of intergalactic gas from the two clusters were slowed down by mutual friction, the dark matter particles simply kept going, even though the dark matter clouds were probably denser than the gas ones. Dark matter can zip not only through ordinary matter, but also through dark matter itself.

Or not. The new mapping of dark matter, galaxies, and intergalactic gas around Abell 520, a “train wreck” of a galaxy cluster, announced today by NASA (see the NASA Web site) seems to throw everything into discussion. By imaging Abell with multiple methods, astrophysicists found a chaotic dismemberment that no theory seems to explain too well now.

In the artist’s illustration above,

the bulk of the matter (blue) is found compared to the individual galaxies (yellow) and the hot gas (red) in the aftermath of a massive galaxy cluster collision. The material shown in blue is dominated by dark matter. As with the Bullet Cluster there are large separation between the regions where the galaxies are most common (peaks 2 and 4) and where most of the hot gas lies (peak 3). However, unlike the Bullet Cluster, a concentration of dark matter is found (peak 3) near the bulk of the hot gas, where very few galaxies are located. In addition, there is an area (peak 5) where there are several galaxies but very little dark matter [courtesy of the X-ray observatory Chandra].

What this means for our understanding of dark matter, it is probably too early to say (I haven’t talked to any experts about this yet). But one thing is for sure: the universe is a bizarre place.