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New light on black holes Apr 30, 2002
Age of the Universe: 14 billion years or infinite? Apr 27, 2002
And now antifreeze in space Apr 21, 2002
Super ant colonies, myxobacteria, and Borg collectives Apr 17, 2002
Ancient dust pushes back age of oldest stars Apr 13, 2002
Chlorophyll detected at Mars Pathfinder landing site? Apr 3, 2002

black hole
New light on black holes
(Apr. 30, 2002)

When is a black hole not a black hole? When it's a (kind of) bubble, say physicists Emil Mottola and Pawel Masur (Los Alamos and Univ. of South Caroline, respectively). Or, more precisely, when it's a gravastar – a gra(vitational) va(cuum) star – effectively, a spherical void of twisted spacetime surrounded by an exotic form of matter. Mottola and Pawel offer an alternative scenario for what happens when a massive dead star collapses. Instead of collapsing all the way down to a black hole, they argue, the rapidly contracting stellar material reaches a critical point at which it undergoes a phase transition similar to the Bose-Einstein condensation, which had been long predicted and was recently observed in the lab. The two theoreticians, presenting their ideas at this year's American Physical Society annual meeting in Albuquerque, think that collapsing stars drop down to the size of the event horizon (where the escape velocity reaches the speed of light), at which point the internal gravitational energy suddenly switches to the new condensate state. "Anything that became trapped by its intense gravity and smashed into it would be obliterated and then assimilated into the shell of the gravastar," explained Mottola. For more, go here (Los Alamos press release).

Age of the Universe: 14 billion years or infinite?
(Apr. 27, 2002)

So now we know: the Universe is just under 14 billion years old. At least, this is the figure that emerges from a recent survey of ancient white dwarfs in a cluster some 7,000 light-years away, carried out using the Hubble Space Telescope. White dwarfs – the degenerate remains of stars up to a few solar masses in size – cool down at a rate pretty well established in theory. NASA scientists used Hubble to take the temperature of these old dwarfs and came up with an age of slightly less than 13 billion years, which, allowing a billion years or so for the first stars to form, places the age of the cosmos at about 14 billion. This is in good agreement with the value obtained from measuring distant galaxy redshifts. For more on this, go here (BBC).

But wait a minute. In the same week, two cosmologists, Neil Turok (University of Cambridge) and Paul Steinhardt (Princeton), have revived the old oscillating model of the Universe in which spacetime goes through an endless series of expansions and contractions. Their new version of the cyclic scenario of growth and shrinkage springs from the astonishing discovery, made a few years ago and more recently confirmed, that the current rate of expansion of the Universe is increasing – a completely unexpected result that indicates there is a negative energy field at work pushing matter apart. Turok and Steinhart believe that this "dark force" drives an unending series of Big Bangs and Big Crunches. So, take your choice: the cosmos we live in is either approaching its 14 billionth birthday or is just the latest incarnation of something that is infinitely old.

For a question & answer session with the two researchers on this, go here (BBC).

Sagittarius B2 molecular cloud
And now antifreeze in space
(Apr. 21, 2002)

Don't bother going to the supermarket for your basic necessities – most of them seem to be floating around for free between the stars. First it was alcohol, then a form of sugar, and now car antifreeze (the 10-atom ethylene glycol). This latest molecule in space was found in a favorite hunting ground of astrochemists: the Sagittarius B2 molecular cloud, in the central region of our Galaxy (see photo). For more on this discovery, go here ( It seems the more we look, the more evidence we find that the clouds from which new star (and planetary) systems form are teeming with surprisingly complex carbon molecules, born on the surface of interstellar ice grains. Hopefully, the Astrobiology Explorer (ABE) infrared telescope project, further development of which has just been given the green light by NASA, will progress through to deployment stage and will then shed much more light on exactly what substances are present between the stars and how they may have influenced the origin of life throughout the cosmos.

Super ant colonies, myxobacteria, and Borg collectives
(Apr. 17, 2002)

The recent discovery of what may be the largest superorganism in the world opens up some interesting lines of speculation for astrobiologists. How far might the phenomenon of the superorganism be carried on other worlds? Is it possible that high intelligence could, in some cases, arise from collectives in which the individuals have very little in the way of brains?

The new-found supercolony, reported by Swiss, French and Danish researchers in The Proceedings of the National Academy of Sciences, has been formed by a species of Argentine ant introduced into Europe about 80 years ago. It stretches 6,000 km – from northern Italy, through the south of France to the Atlantic coast of Spain – with many billions of related ants occupying millions of nests. While ants from rival nests normally fight each other to the death, ants from the supercolony can recognize each other and cooperate, even if they come from nests at opposite ends of the colony's range. The Argentine species (Linepithema humile) probably came into Europe on imported plants, pushing back the 20 or so indigenous species of European ant, though why the supercolony emerged isn't clear. The scientists who identified it suggest that the initial success of the alien invaders would have led to high nest densities, which in turn would have favoured cooperative behaviour over aggression. Evolution would then have reinforced this superiority because nests devoid of internal strife would have had time and resources to fight off their enemies. As Laurent Keller, of the University of Lausanne, Switzerland, point out: "It is interesting to see that introduction in a new habitat can change social organization."

Of course, there are many other examples of supercolonial organisms on Earth. At the microscopic level, it's long been known that Myxobacteria spend part of their lives as superorganisms-effectively, multicellular life-forms in which each cell is a bacterium. Such superorganisms display emergent properties that are quite beyond the capabilities of the individual members of which they're composed. Borg In their collective state, for example, roaming colonies of Myxobacteria show impressive responsiveness in identifying and attacking solitary prey microbes. They veer out of their way if they detect what might be food, and then turn to continue their search if the object proves inedible.

If creatures as lowly as ants, or even bacteria, can display intelligence en masse, it raises the question of what really smart individuals, like ourselves, could do, if we formed a genuine superorganism (the future Internet?). The idea has been explored many times in science fiction, most recently by the script-writers of Star Trek with their "Borg collective." For more speculation on intelligent superorganisms and hive intelligence, go here.

quasars in the early universe
Ancient dust pushes back age of oldest stars
(Apr. 13, 2002)

In case you're worried how long it's been since you dusted behind that row of books on your shelf, look at it in perspective. Astronomers have just found evidence of dust that's at least 90% of the age of the Universe – more than 10 billion years old. It has been detected in quasars that existed only a billion years or so after the Big Bang by astronomers using the James Clerk Maxwell Telescope on Mauna Kea, in Hawaii. The quasars examined appear to contain large amounts of carbon and silicate dust, indicating they have already witnessed the birth and death of a good many stars that produced this "heavy" interstellar debris. Of course, the presence of such dust also suggests that the raw building materials for planets were available at this early juncture. And for those SETI fans who care to indulge in a little hypothesizing, this means that if intelligent life evolved on any of those worlds, and surivived to this day, it would be quite a few billion years ahead of us by now!

For more on this, go here (BBC).

Mars Pathfinder
Chlorophyll detected at Mars Pathfinder landing site?
(Apr. 3, 2002)

The Second Astrobiology Science Conference begins at NASA Ames Research Center on April 7 and surely one of the most intriguing announcements to be made is of the suggested possible detection of chlorophyll at the Mars Pathfinder landing site. These results, to be presented at the poster session by Carol Stoker and Pascal Ashwaden, both of NASA Ames, are summarized in the following abstract from the Conference proceedings:

The Superpan, an image product from the Pathfinder lander camera, is a multispectral panorama of the Pathfinder landing site acquired in 15 wavelengths in the spectral range 440-1100 nm. We have performed an automated search of the Superpan image cubes for the spectral signature associated with chlorophyll. First, images were calibrated to radiance values and then the multispectral images were co-registered to subpixel accuracy. An automated pixel-to-pixel search was performed on a 3-filter set of images (530 nm, 670 nm, 980 nm) to identify pixels where the following condition was met: 530 nm > 670 nm, and 980nm > 670 nm. Thus, we searched for the spectral signature associated with red light absorption by chlorophyll. When this case was met by the search routine, we plotted a full spectrum for the involved pixels and carefully examined the images. The condition was met for small areas in six image cases. All of these cases occur in near field images, where resolution is highest. Four of the cases occur on the spacecraft and appear to be associated with spacecraft structure. Two intriguing cases occur in small areas on the ground near the spacecraft.


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