- Gallery: 10 Visions of the Postnatural World
- NASA Finds New Arsenic-Based Life Form in California
- NASA Finds New Life Form
- Twinkling Stars May Reveal Human-Size Wormholes
Posted: 02 Dec 2010 12:12 PM PST
<< Previous | Next >>
Able to lament the tragedy of nature's disruption and glory in the vitality of its survivors, Alexis Rockman is the perfect artist for the anthropocene.
The son of an archaeologist, the New York-based painter's spanned both rural Peru and the American Museum of Natural History, prefiguring the fascinations that would shape his career: time, biology, ecology and humanity.
Traces of museum dioramas can be seen in works like his 1992 mural-sized Evolution (detail, above). So can the Hudson River school landscape tradition, Renaissance realism and a prehistory-infused apocalyptic futurism in which humans shape but can't short-circuit the continuum of life.
The Smithsonian American Art Museum is now hosting the first major Rockman retrospective, entitled -- with a nod to Rachel Carson's Silent Spring -- "Alexis Rockman: A Fable Tomorrow". He talked to Wired.com about his work.
Posted: 02 Dec 2010 11:37 AM PST
When cooking up the stuff of life, you can't just substitute margarine for butter. Or so scientists thought.
But now researchers have coaxed a microbe to build itself with arsenic in the place of phosphorus, an unprecedented substitution of one of the six essential ingredients of life. The bacterium appears to have incorporated a form of arsenic into its cellular machinery, and even its DNA, scientists report online Dec. 2 in Science.
Arsenic is toxic and is thought to be too chemically unstable to do the work of phosphorus, which includes tasks such as holding DNA in a tidy double helix, activating proteins and getting passed around to provide energy in cells. If the new results are validated, they have huge implications for basic biochemistry and the origin and evolution of life, both on Earth and elsewhere in the universe.
"This is an amazing result, a striking, very important and astonishing result — if true," says molecular chemist Alan Schwartz of Radboud University Nijmegen in the Netherlands. "I'm even more skeptical than usual, because of the implications. But it is fascinating work. It is original, and it is possibly very important."
The experiments began with sediment from eastern California's Mono Lake, which teems with shrimp, flies and algae that can survive the lake's strange chemistry. Mono Lake formed in a closed basin — any water that leaves does so by evaporation — making the lake almost three times as salty as the ocean. It is highly alkaline and rich in carbonates, phosphorus, arsenic and sulfur.
Led by Felisa Wolfe-Simon of NASA's Astrobiology Institute and the U.S. Geological Survey in Menlo Park, California, the researchers cultured microbes from the Lake Mono sediment. The microbes got a typical diet of sugar, vitamins and some trace metals, but no phosphate, biology's favorite form of phosphorus. Then the team started force-feeding the critters arsenate, an analogous form of arsenic, in greater and greater quantities.
One microbe in particular — now identified as strain GFAJ-1 of the salt-loving, mostly marine family Halomonadaceae — was plucked out and cultured in test tubes. Some were fed loads of arsenate; others got phosphate. While the microbes subsisting on arsenate didn't grow as much as those getting phosphate, they still grew steadily, doubling their ranks every two days, says Wolfe-Simon. And while the research team couldn't eliminate every trace of the phosphate from the original culture, detection and analytical techniques suggests that GFAJ-1 started using arsenate as a building block in phosphate's place.
"These data show that we are getting substitution across the board," Wolfe-Simon says. "This microbe, if we are correct, has solved the challenge of being alive in a different way."
Arsenic sits right below phosphorus in the periodic table and so, chemically speaking, isn't that different, Wolfe-Simon notes. And of the six essential elements of life — carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur (aka CHNOPS) — phosphorus has a relatively spotty distribution on the Earth's surface. If a microbe in a test tube can be coerced to live on arsenic, perhaps life's primordial home was also arsenic-rich and life that used phosphorus came later. A "shadow biosphere" of arsenic-based life may even exist unseen on Earth, or on some lonely rock in space.
"It isn't about arsenic, and it isn't about Mono Lake," says Wolfe-Simon. "There's something fundamental about understanding the flexibility of life. Any life, a microbe, a tree, you grind it up and it's going to be CHNOPS. But we have a single sample of life. You can't look for what you don't know."
Similarities between arsenic and phosphorus are also what make the element so poisonous. Life often can't distinguish between the two, and arsenic can insinuate itself into cells. There, it competes with phosphorus, grabs onto sulfur groups, or otherwise gums up the works, causing cell death. Some microbes "breathe" by passing electrons to arsenic, but even in those cases the toxic element stays outside the cell.
Researchers are having a hard time wrapping their minds around arsenate doing the job of phosphate in cells. The 'P' in ATP, the energy currency for all of life, stands for phosphate. And the backbone of the DNA double helix, the molecule containing the genetic instructions for life, is made of phosphate. Basic biochemistry says that these molecules would be so unstable that they would fall apart if they were built with arsenate instead of phosphate.
"Every organism that we know of uses ATP and phosphorylated DNA," says biogeochemist Matthew Pasek of the University of South Florida in Tampa. He says the new research is both fascinating and fantastic. So fantastic, that a lot of work is needed to conclusively show exactly how the microbe is using arsenate.
Both phosphate and arsenate can clump up into groups, and with their slightly negative electric charge, slightly positive DNA would be attracted to such clumps, says Pasek. Perhaps the arsenic detected in the DNA fraction was actually a nearby clump that the DNA wrapped itself around, he speculates.
The microbe may be substituting for phosphate with discretion, says geochemist Everett Shock of Arizona State University in Tempe, using arsenic in some places but not others. But Shock says the real value of the work isn't in the specifics. "This introduces the possibility that there can be a substitution for one of the major elements of life," he says. Such research "stretches the perspective. Now we'll have to see how far this can go."
Posted: 02 Dec 2010 09:36 AM PST
By Jesus Diaz, Gizmodo
Hours before its special news conference today, the cat is out of the bag: NASA has discovered a completely new life form that doesn't share the biological building blocks of anything currently living on planet Earth. This changes everything.
At its conference today, NASA scientist Felisa Wolfe-Simon will announce that NASA has found a bacteria whose DNA is completely alien to what we know today. Instead of using phosphorus, the bacteria uses arsenic. All life on Earth is made of six components: carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. Every being, from the smallest amoeba to the largest whale, shares the same life stream. Our DNA blocks are all the same.
But not this one. This one is completely different. Discovered in poisonous Mono Lake, California, this bacteria is made of arsenic, something that was thought to be completely impossible. While Wolfe-Simon and other scientists theorized that this could be possible, this is the first discovery. The implications of this discovery are enormous to our understanding of life itself and the possibility of finding beings in other planets that don't have to be like planet Earth.
No details have been disclosed about the origin or nature of this new life form. We will know more today at 2 p.m. EST but, while this life hasn't been found in another planet, this discovery does indeed change everything we know about biology. I don't know about you, but I've not been so excited about a bacteria since my STD tests came back clean. And that's without counting yesterday's announcement on the discovery of a massive number of red dwarf stars, which may harbor trillions of Earths.
For more current in-depth coverage, read Science News.
Source: [NOS — in Dutch]
Images: 1) New bacteria./Science/AAAS. 2) Mono Lake./Henry Bortman.
Posted: 02 Dec 2010 04:00 AM PST
If wormholes big enough to fit a human or a spaceship exist, telescopes should be able to detect any wavering starlight the space-time shortcuts cause while moving in front of a distant star.
Star brightness would fluctuate from a wormhole because of gravitational lensing, caused when a massive object (such as a galaxy) warps the fabric of space and bends light around it. The effect, which resembles the distortion of objects behind a thick lens, exaggerates with increasingly massive objects.
When it comes to wormhole hunting, said Nagoya University astrophysicist Fumio Abe, looking for the distant signatures of smaller gravitational lenses, called microlenses, is the way to go.
"Gravitational microlensing in stars has already been observed, but the variation of the brightness by a wormhole would be different from any ordinary star," said Abe, whose wormhole-detecting methodology appears Dec. 10 in The Astrophysical Journal.
Wormholes are yet-to-be-observed warpings of space and time so extreme that they connect one point to another through a tunnel-like throat. Such connections may be able to transport something — a photon of light or a spaceship — to another galaxy, the edge of the universe, another universe entirely or possibly backward or forward in time.
"Wormholes can be a very uncomfortable subject for scientists who study general relativity because they make it possible to create time machines and travel faster than light," said John G. Cramer, a University of Washington experimental physicist who was not involved in the study.
Albert Einstein's theory of general relativity implied the existence of gravitational microlensing, an effect proven to exist in 1919 when the sun's gravity shifted the apparent position of a star during a total solar eclipse. There are now more than a dozen efforts underway to study the phenomenon.
"We already have lots of data on gravitational lensing, so we can study the existence or nonexistence of wormholes simply by reanalyzing the data," Abe said. "We can find wormholes if they exist or set some kind of limit on their abundance."
Physicists from around the world are intrigued by and supportive of the proposal, but all of them, Abe included, emphasize the words "if" when it comes to pondering wormhole existence.
"This is a neat calculation showing that, if wormholes are out there, this would give us a fighting chance to see them," said Matt Visser, a theoretical physicist at Victoria University of Wellington in New Zealand (also not involved in the study). "But wormholes are speculative stuff. A lot of work has been done with them, but primarily as a theoretical tool to stretch Einstein's ideas to their limits, to break them and see what drops out the other end."
Einstein and physicist Nathan Rosen proposed the existence of wormholes in 1935, dubbing them Einstein-Rosen bridges. Decades later, the objects were mathematically shown to be unstable: Before even a piece of light could have a chance to fly through, the throat of the wormhole would close up for good.
More recent work by Michael Morris and Kip Thorne, however, suggests that highly exotic negative mass and energy — thought to behave counter to gravity — could prop open a wormhole's throat long enough for a courageous human to sneak through.
Nevertheless, the challenges to create wormholes in the lab are enormous.
"For a wormhole about 1 meter across, big enough to fit a person, you'd need a Jupiter's worth of negative mass converted into negative energy — think E = mc2 — to hold the throat open and hope it remains stable," Visser said. "That's an incredible amount."
Alien technology advanced enough to collect negative energy and create a wormhole is a more likely than a natural scenario, said Cramer and Visser, but not much can be ruled out because our knowledge is purely theoretical.
"Some say wormholes may have formed at a very early stage of the universe, right after the Big Bang," Abe said, noting that the energy density then may have been extreme enough to both pop wormholes into existence and stabilize them.
Such large and traversable Ellis wormholes, as they're called (among other names), are the kind Abe's method may find if they're lurking in the nearby cosmos and pass in front of a star.
"On a graph (see below), the star's changing brightness would look something like some bump at the center, but with gutters on both sides of the peak," Abe said. "Gravitational lensing by ordinary stars does not show the gutters."
With minor tweaks to telescope software, a couple of instruments could look for Abe's distinctive light signatures and confirm or constrain the existence of wormholes within a few years, Abe said. One is the Microlensing Observations in Astrophysics telescope, and the other is the Optical Gravitational Lensing Experiment telescope.
"If the wormhole exists, it shows some possibility of a traveling or time machine. But practically, using them in this way is almost impossible because they're likely very distant from Earth, probably at least 10,000 light-years," Abe said. "It may not make sense to go through a wormhole because it would take such a long time to travel to one."
What many scientists would be excited about is the potential to reconcile conflicting ideas about gravity on both universe and quantum scales.
"If they do turn out to exist, I'll be ecstatic," Visser said. "In the meantime, they're great props for science-fiction novels and movies."
Images: 1) A Shanghai subway tunnel. Credit: Flickr/Stuck in Customs
|You are subscribed to email updates from Johnus Morphopalus's Facebook notes |
To stop receiving these emails, you may unsubscribe now.
|Email delivery powered by Google|
|Google Inc., 20 West Kinzie, Chicago IL USA 60610|