Tag archives: astrobiology
By Michael Bishop
In the 60 years since James Watson and Francis Crick brought physics and biology together to unveil the molecular structure of DNA, the boundary between the two disciplines has continued to become increasingly blurred.
In this post-genomic era, ever more principles from physics have been applied to living systems in an attempt to understand complexity at all levels.
Yet cultural differences still exist between physicists and biologists, as is made clear in a set of excellent perspectives in the journal Physical Biology, published by IOP Publishing, which also publishes Physics World.
In “Perspectives on working at the physics–biology interface”, a group of eminent scientists give their accounts of working at the interface of physics and biology, describing the opportunities that have presented themselves and outlining some of the problems that they continue to face when working across two fields with quite different traditions.
By Tushna Commissariat
Early last week, astronomers announced that they had found the first Earth-sized exoplanet that is comfortably within the habitable zone of its parent star, using NASA’s Kepler telescope. The new planet, dubbed Kepler-186f, is a close cousin of the Earth as it has a radius that is only 10% larger than that of the Earth, meaning that it could have liquid water on its surface, allowing for the tantalizing possibility of some form of life to exist upon it. At last count, Kepler has now discovered and confirmed 1706 exoplanets.
So it was rather interesting to come across two stories that looked at the implications of life beyond our planetary neighbourhood. Paul Gilster, who writes the Centauri Dreams blog had a rather interesting post on how artists and illustrators need to work with scientists to depict each new exoplanet, to make the images look visually stunning, while still being scientifically accurate. Gilster also talks specifically about the image (see above) that illustrates the newly found Kepler-186f.
By Michael Banks
Wagner, together with his colleague Luis Sancho, filed a federal lawsuit in the US District Court in Honolulu in 2008 to prevent the LHC from starting up. In the lawsuit, Wagner and Sancho claimed that if the LHC were switched on, then the Earth would eventually fall into a growing micro black hole, thus converting our planet into a medium-sized black hole, around which the Moon, artificial satellites and the International Space Station would orbit.
By Tushna Commissariat
Just when we thought that it couldn’t possibly have any more practical applications, everybody’s favourite “wonder material” graphene is going to be used to develop “stronger, safer, and more desirable condoms”. Thanks to a Grand Challenges Explorations grant of £62,123 from the Bill and Melinda Gates Foundation, scientists at the University of Manchester will use graphene to develop new “composite nanomaterials for next-generation condoms, containing graphene”. Unsurprisingly, the story made all the national newspapers with the BBC, the Guardian, the Telegraph and the Independent all having their say. The Guardian also noted that industrial graphene-producer Applied Graphene Materials’ shares jumped by 40% during its stock-market debut, the day before the above story broke. You can read more about graphene’s many potential applications on page 50 of Physics World’s anniversary issue, a free PDF download of which is available here.
By Ian Randall
In the modish hunt for exoplanets, the holy grail is discovering such a body within the habitable zone of a star – offering a tantalizing potential for extraterrestrial life. If our solar system is anything to go by, we can expect most planets to form outside of the confines of this zone. What if, however, the habitable zone is really larger than we thought?
This is the idea put forward by Sean McMahon from the University of Aberdeen, Scotland, and colleagues in a recent paper – proposing that the existing definition of the habitable zone overlooks the potential for life to survive below the surface of terrestrial planets that currently lie outside the zone’s reach.
By Hamish Johnston
Finding the fossilized remains of extraterrestrial life in a meteorite would surely be the biggest scientific discovery of the century. That’s what appears to be reported in a paper published in the Journal of Cosmology and available on the arXiv preprint server.
Gliese 667 is one of two multiple star systems known to host planets below 10 Earth masses. (Courtesy: ESO/L Calçada)
By Tushna Commissariat
If you have thought about planets with two or more suns ever since you saw the dual suns of Tatooine in the first Star Wars film, looks like you are on the same wavelength as some astrobiologists. Jack O’Malley-James, a PhD student at the University of St Andrews, Scotland, has been studying what kind of habitats would exist on Earth-like planets orbiting binary or multiple star systems. He shared his results with peers at the RAS National Astronomy Meeting in Llandudno, Wales on Tuesday 19th April.
O’Malley-James and his team have been running simulations for planets that would orbit multiple star systems and trying to understand the kind of vegetation that might flourish there, depending on the type of stars in the system. Energy via photosynthesis is the foundation for majority of life on Earth, and so it is natural to look for the possibility of photosynthetic processes occurring elsewhere.
With different types of stars occurring in the same system, there would be different spectral sources of light shining on the same planet. Because of this plants may evolve that photosynthesize all types of light, or different plants may choose specific spectral types. The latter would seem more plausible for plants exposed to one particular star for long periods, say the researchers.
Their simulations suggest that planets in multi-star systems may host exotic forms of the plants we see on Earth. “Plants with dim red dwarf suns for example, may appear black to our eyes, absorbing across the entire visible wavelength range in order to use as much of the available light as possible,” says O’Malley-James. He also believes the plants may be able to use infrared or ultraviolet radiation to drive photosynthesis.
The team simulated combinations of G-type stars (yellow stars like our Sun) and M-type stars (red-dwarf stars), with a planet identical to Earth, in a stable orbit around the system, within its habitable “Goldilocks zone”. This was because Sun-like stars are known to host exoplanets and red dwarfs are the most common type of star in our galaxy, often found in multi-star systems, and are old and stable enough for life to have evolved.
While the binary systems were not exact copies of any particular observed systems, plenty of M-G star binary systems exist within our own galaxy. O’Malley-James calculated the maximum amount of light per unit area- referred to as the “peak photon flux density” from each of the stars as seen on the planets for each set of simulations. This was compared to the peak photon flux density on Earth to determine whether Earth-like photosynthesis would occur.
Factors like star separation were taken into consideration, to give the best possible scenario for photosynthesis. “We kept the stars as close to the planet as we could, so that there would be a useful photon flux from each one [star] on the planet’s surface while still maintaining a stable planetary orbit and a habitable surface temperature,” says O’Malley James.