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First ‘habitable’ exoplanet confirmed

PARIS: A rocky world orbiting a nearby star was confirmed as the first planet outside our Solar System to meet key requirements for sustaining life.

Modelling of planet Gliese 581d shows it has the potential to be warm and wet enough to nurture Earth-like life, scientists have said. It orbits a red dwarf star called Gliese 581, located around 20 light years from Earth, which makes it one of our closest neighbours.

Gliese 581d orbits on the outer fringes of the star’s ‘Goldilocks zone’, where it is not so hot that water boils away, nor so cold that water is perpetually frozen. Instead, the temperature is just right for water to exist in liquid form.

Zarmina’s World

“With a dense carbon dioxide atmosphere – a likely scenario on such a large planet – the climate of Gliese 581d is not only stable against collapse but warm enough to have oceans, clouds and rainfall,” France’s National Centre for Scientific Research (CNRS) said.

More than 500 planets orbiting other stars have been recorded since 1995, detected mostly by a tiny wobble in stellar light. Exoplanets are named after their star and listed alphabetically, in order of discovery.

Until now, the big interest in Gliese 581’s roster of planets focussed on Gliese 581g. It leapt into the headlines last year as ‘Zarmina’s World’, after its observers announced it had roughly the same mass as Earth’s and was also close to the Goldilocks zone.

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ELASTIC “unparticles” could explain a mysterious signal glimpsed at a particle collider a year ago. That would link a tenuous but intriguing idea to one of the biggest mysteries in physics: why matter prevails over antimatter in the universe.

“I think this will increase the unparticle’s credibility as a theory,” says Run-Hui Li of Yonsei University in Seoul, South Korea, the leader of one of two teams proposing the link.

Matter and antimatter are thought to have been created in equal amounts after the big bang, yet something has caused matter to be far more dominant than antimatter, at least in our patch of the universe.

A possible explanation is that some physical processes favour matter. For example, according to the standard model of particle physics, particles known as B mesons constantly switch, or mix, between their matter and antimatter forms. Because it is slightly easier for an anti-B meson to become a normal B meson than vice versa, an imbalance accrues. This “uneven mixing” gets transferred to the particles produced when B mesons decay, but alone is not big enough to explain the observed matter-antimatter asymmetry.

Previously, several teams have glimpsed examples of asymmetry even larger than the standard model predicts. In May 2010, researchers at the Fermi National Accelerator Laboratory in Batavia, Illinois, reported a 1 per cent preference for the number of B mesons produced in their particle smasher, the Tevatron (arxiv.org/abs/1005.2757). This is 40 times larger than the imbalance predicted by the standard model.

Two separate groups now suggest an explanation for this larger asymmetry lies in the unparticle, a hypothetical entity conjured up in 2007 by theorist Howard Georgi of Harvard University. Georgi suggested that a property known as scale invariance – seen in fractal-like patterns that remain unchanged even when you zoom in and out to different scales, like the branching of redwood trees and the jagged edges of coastlines – could apply to individual particles too. The charge and spin of unparticles would be fixed but, counter-intuitively, their mass would somehow vary depending on the scale at which an observer viewed the particle.

Such unparticles could play a role in a popular proposed extension to the standard model, known as supersymmetry.

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The artificial leaf shows particular promise as an inexpensive source of electricity for homes of the poor in developing countries. Our goal is to make each home its own power station.

‘One can envision villages in India and Africa not long from now purchasing an affordable basic power system based on this technology.’

The device bears no resemblance to Mother Nature’s counterparts on oaks, maples and other green plants, which scientists have used as the model for their efforts to develop this new genre of solar cells.

About the shape of a poker card but thinner, the device is fashioned from silicon, electronics and catalysts, substances that accelerate chemical reactions that otherwise would not occur, or would run slowly.

Placed in a single gallon of water in a bright sunlight, the device could produce enough electricity to supply a house in a developing country with electricity for a day, Nocera said.

It does so by splitting water into its two components, hydrogen and oxygen.

The hydrogen and oxygen gases would be stored in a fuel cell, which uses those two materials to produce electricity, located either on top of the house or beside it.

Nocera, who is with the Massachusetts Institute of Technology, points out that the ‘artificial leaf’ is not a new concept.

The first artificial leaf was developed more than a decade ago by John Turner of the U.S. National Renewable Energy Laboratory in Boulder, Colorado.

Although highly efficient at carrying out photosynthesis, Turner’s device was impractical for wider use, as it was composed of rare, expensive metals and was highly unstable — with a lifespan of barely one day.

Nocera’s new leaf overcomes these problems.

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In order to detect signs of past or present life on Mars — if it is in fact true that we’re related — then a promising strategy would be to search for DNA or RNA, and specifically for particular sequences of these molecules that are nearly universal in all forms of terrestrial life. That’s the strategy being pursued by MIT research scientist Christopher Carr and postdoctoral associate Clarissa Lui, working with Maria Zuber, head of MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS), and Gary Ruvkun, a molecular biologist at the Massachusetts General Hospital and Harvard University, who came up with the instrument concept and put together the initial team. Lui presented a summary of their proposed instrument, called the Search for Extra-Terrestrial Genomes (SETG), at the IEEE Aerospace Conference this month in Big Sky, Mont.

The idea is based on several facts that have now been well established. First, in the early days of the solar system, the climates on Mars and the Earth were much more similar than they are now, so life that took hold on one planet could presumably have survived on the other. Second, an estimated one billion tons of rock have traveled from Mars to Earth, blasted loose by asteroid impacts and then traveling through interplanetary space before striking Earth’s surface. Third, microbes have been shown to be capable of surviving the initial shock of such an impact, and there is some evidence they could also survive the thousands of years of transit through space before arriving at another planet.

If the sun were just a tiny point of light and Earth had no atmosphere, then day and night would each be exactly 12 hours long on a spring equinox day.

But to begin with, as seen from Earth, the sun is nearly as large as a little fingertip held at arm’s length, or half a degree wide.

Sunrise is defined as the moment the top edge of the sun appears to peek over the horizon. Sunset is when the very last bit of the sun appears to dip below the horizon.

The spring equinox, however, occurs when the center of the sun crosses the Equator.

Plus, Earth’s atmosphere bends the sunlight when it’s close to the horizon, so the golden orb appears a little higher in the sky than it really is.

As a result, the sun appears to be above the horizon a few minutes earlier than it really is.

Therefore, on the spring equinox day, the daylight hours are actually longer than the length of time between when the sun crosses the horizon at dawn and when the sun crosses the horizon at sunset.

“The idea of consciousness as a “show” is ultimately derived from the bankrupt representational theory of the mind – a notion that things are present to us by virtue of being “represented” or “modelled” in the brain. You cannot get to representation, however, without prior (conscious, first-order) presentation, so the latter cannot explain the former. Neuroscientists of consciousness try to elude this obvious objection by asserting that representations are not (necessarily) conscious. In fact, all sorts of aspects of consciousness are not conscious after all.

According to Nicholas Humphrey, “before consciousness ever arose, animals were engaged in some kind of inner monitoring of their own responses to sensory stimulation”. What is “inner” about unconscious processes, material events in the material brain? And how can they amount to monitoring? These questions are not silenced by the author’s reassurance that consciousness is “the product of some kind of illusion chamber, a charade”. Nor does Humphrey tell us how he awoke from his consciousness to discover that it is an illusion.”

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