Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Search for alien life challenges current concepts, says U. of Colorado prof.

20.02.2006


For scientists eying distant planets and solar systems for signs of alien activity, University of Colorado at Boulder Professor Carol Cleland suggests the first order of business is to keep an open mind.



It may be a mistake to try to define life, given such definitions are based on a single example -- life on Earth, said Cleland, a philosophy professor and fellow at the NASA-funded CU-Boulder Center for Astrobiology. The best strategy is probably to develop a "general theory of living systems," she said.

Many biologists agree the best definition of living systems today is the "chemical Darwinian definition" involving self-sustaining chemical systems that undergo evolution at the molecular level, she said. But the theory is limited in that life on Earth probably resulted from physical and chemical "contingencies" present at the time of its origin on the planet.


"What we really need to do is to search for physical systems that challenge our current concept of life, systems that both resemble familiar life and differ from it in provocative ways," she said. Cleland participated in an astrobiology symposium at the annual American Association for the Advancement of Science meeting held in St. Louis Feb. 16 to Feb. 20.

In 1976, for example, NASA’s Viking 1 spacecraft conducted automated biology experiments on Mars by mixing soil samples with radioactively labeled nutrients to determine if metabolic "burps" from possible extraterrestrial microbes could be detected, she said. Although positive readings convinced at least some team scientists that life was present, a subsequent investigation by a second Viking instrument failed to find evidence of organic molecules on the planet’s surface.

"Initially, the scientists were ready to break out the champagne," said Cleland. "But because subsequent investigations yielded baffling results that didn’t fit the original metabolic definition of life they were working with, NASA eventually concluded the original signal was not evidence of life. This is an experiment that is still debated today, and it’s a classic example of an anomaly."

Although there are more than 100 combinations of nucleic acids in nature, terrestrial life constructs all of its proteins from only about 20 of them, suggesting a single origin for life on Earth, said Cleland. "It’s very difficult to generalize about life based on just one example," she said.

An article by Cleland and CU-Boulder molecular, cellular and developmental biology Professor Shelley Copley, published online in the Jan. 16 International Journal of Astrobiology, explores the idea that an "alternative microbial life" may exist on Earth. Such a "shadow biosphere" could have a different molecular architecture and biochemistry than known life and would be undetectable with current techniques like microscopy, cell cultivation and Polymerase Chain Reaction amplification, the authors wrote.

Despite new suites of sophisticated instruments developed in recent years, the ability of scientists to detect life on Mars or in another solar system is probably very limited, Cleland said. "If the DNA in an alien organism was even slightly different than the DNA in life on Earth, with a different suite of nucleotide bases to encode genetic information, we probably wouldn’t be able to recognize it. "

So what might be out there? "It’s not too far-fetched to imagine an alien microbe whose genetic material directly and adaptively changes in response to different environmental conditions," said Cleland. "Instead of looking for life as we know it, scientists may be better served to look for anomalies, which amounts to looking for life as we don’t know it."

In the past decade, scientists have discovered more than 170 new planets around other stars, a number that seems to grow by the month due to clever new planet-hunting techniques, Cleland said. In the future, astrobiologists surveying other planets will no doubt encounter non-living systems that are "really weird," she said.

"In such cases, it probably is best to suspend judgment," she said. "The great strength of science is its tentativeness, and through history, it has been the careful analysis of anomalies that have eventually changed scientific paradigms."

Carol Cleland | EurekAlert!
Further information:
http://www.colorado.edu

More articles from Physics and Astronomy:

nachricht Further Improvement of Qubit Lifetime for Quantum Computers
09.12.2016 | Forschungszentrum Jülich

nachricht Electron highway inside crystal
09.12.2016 | Julius-Maximilians-Universität Würzburg

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>