David Kirkpatrick

March 2, 2010

Going beyond radio in the search for ET

I’ve been a longtime supporter of SETI’s efforts, but I also welcome any new ideas in the search for extraterrestrial intelligence. These ideas from Paul Davies sound worthwhile.

The release

Widening the search for extraterrestrial intelligence

The Search for Extraterrestrial Intelligence (SETI) has been dominated for its first half century by a hunt for unusual radio signals. But as he prepares for the publication of his new book The Eerie Silence: Are We Alone?, Paul Davies tells Physics World readers why bold new innovations are required if we are ever to hear from our cosmic neighbours.

Writing exclusively in March’s Physics World, Davies, director of BEYOND: Center for Fundamental Concepts in Science at Arizona State University in the US, explains why the search for radio signals is limited and how we might progress.

As Davies writes, “speculation about SETI is bedevilled by the trap of anthropocentrism – a tendency to use 21st-century human civilisation as a model for what an extraterrestrial civilisation would be like… After 50 years of traditional SETI, the time has come to widen the search from radio signals.”

Questioning the idea of an alien civilisation beaming radio signals towards Earth, Davies explains that even if the aliens were, say, 500 light years away (close by SETI standards), the aliens would be communicating with Earth in 1510 – long before we were equipped to pick up radio signals.

While SETI activity has been concentrated in radio astronomy, from Frank Drake’s early telescope to the more recent Allen Telescope Array, astronomers have only ever been met with an (almost) eerie silence.

Davies suggests that there may be more convincing signs of intelligent alien life, either here on Earth in the form of bizarre microorganisms that somehow found their way to Earth, or in space, through spotting the anomalous absence of, for example, energy-generating particles that an alien life form might have harvested.

“Using the full array of scientific methods from genomics to neutrino astrophysics,” Davies writes, “we should begin to scrutinise the solar system and our region of the galaxy for any hint of past or present cosmic company.”

Following the publication of his book, The Eerie Silence, Davies will be giving a Physics World webinar at 4pm (BST) on Wednesday 31 March. You can view the webinar live at http://www.physicsworld.com or download it afterwards.

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Also in the March edition:

  • Getting intimate with Mars – robotic rovers are starting to unravel the secrets of the red planet but, according to one NASA expert, we would discover so much more if we brought samples back to Earth.
  • The Hollywood actor Alan Alda, star of M*A*S*H and The West Wing, who has a deep and passionate interest in science, is now part of an innovative US project to help scientists to communicate.

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July 31, 2009

Introducing graphane

Filed under: Science — Tags: , , , , , — David Kirkpatrick @ 3:58 pm

I’ve done plenty of blogging on the nanomaterial graphene, now here’s an introduction to graphane, its insulating offshoot. Just like with graphene, there’s high hopes for graphane applications.

The release:

From graphene to graphane, now the possibilities are endless

Ever since graphene was discovered in 2004, this one-atom thick, super strong, carbon-based electrical conductor has been billed as a “wonder material” that some physicists think could one day replace silicon in computer chips.

But graphene, which consists of carbon atoms arranged in a honeycomb lattice, has a major drawback when it comes to applications in electronics – it conducts electricity almost too well, making it hard to create graphene-based transistors that are suitable for integrated circuits.

In August’s Physics World, Kostya Novoselov – a condensed-matter physicist from the Manchester University group that discovered graphene — explains how their discovery of graphane, an insulating equivalent of graphene, may prove more versatile still.

Graphane has the same honeycomb structure as graphene, except that it is “spray-painted” with hydrogen atoms that attach themselves to the carbon. The resulting bonds between the hydrogen and carbon atoms effectively tie down the electrons that make graphene so conducting. Yet graphane retains the thinness, super-strength, flexibility and density of its older chemical cousin.

One advantage of graphane is that it could actually become easier to make the tiny strips of graphene needed for electronic circuits. Such structures are currently made rather crudely by taking a sheet of the material and effectively burning away everything except the bit you need. But now such strips could be made by simply coating the whole of a graphene sheet – except for the strip itself – with hydrogen. The narrow bit left free of hydrogen is your conducting graphene strip, surrounded by a much bigger graphane area that electrons cannot go down.

As if this is not enough, the physicists in Manchester have found that by gradually binding hydrogen to graphene they are able to drive the process of transforming a conducting material into an insulating one and watch what happens in between.

Perhaps most importantly of all, the discovery of graphane opens the flood gates to further chemical modifications of graphene. With metallic graphene at one end and insulating graphane at the other, can we fill in the divide between them with, say, graphene-based semiconductors or by, say, substituting hydrogen for fluorine?

As Professor Novoselov writes, “Being able to control the resistivity, optical transmittance and a material’s work function would all be important for photonic devices like solar cells and liquid-crystal displays, for example, and altering mechanical properties and surface potential is at the heart of designing composite materials. Chemical modification of graphene – with graphane as its first example – uncovers a whole new dimension of research. The capabilities are practically endless.”

 

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