Replies to post #144 on Extraterrestrial

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Hawking: Humans Must Spread Out in Space
HONG KONG, Jun. 14, 2006

(AP) The survival of the human race depends on its ability to find new homes elsewhere in the universe because there's an increasing risk that a disaster will destroy Earth, world-renowned physicist Stephen Hawking said Tuesday.

Humans could have a permanent base on the moon in 20 years and a colony on Mars in the next 40 years, the British scientist told a news conference.

"We won't find anywhere as nice as Earth unless we go to another star system," added Hawking, who came to Hong Kong to a rock star's welcome Monday. Tickets for his lecture Thursday were sold out.

Hawking said that if humans can avoid killing themselves in the next 100 years, they should have space settlements that can continue without support from Earth.

"It is important for the human race to spread out into space for the survival of the species," Hawking said. "Life on Earth is at the ever-increasing risk of being wiped out by a disaster, such as sudden global warming, nuclear war, a genetically engineered virus or other dangers we have not yet thought of."

The 64-year-old scientist _ author of the global best-seller "A Brief History of Time" _ uses a wheelchair and communicates with the help of a computer because he suffers from a neurological disorder called amyotrophic lateral sclerosis, or ALS.

One of the best-known theoretical physicists of his generation, Hawking has done groundbreaking research on black holes and the origins of the universe, proposing that space and time have no beginning and no end.

However, Alan Guth, a physics professor at the Massachusetts Institute of Technology, said Hawking's latest observations were something of a departure from his usual research and more applicable to survival over the long-term.

"It is a new area for him to look at," Guth said. "If he's talking about the next 100 years and beyond, it does make sense to think about space as the ultimate lifeboat."

But, he added, "I don't see the likely possibility within the next 50 years of science technology making it easier to survive on Mars and on the moon than it would be to survive on earth."

"I would still think that an underground base, for example in Antarctica, would be easier to build than building on the moon," Guth said.

Joshua Winn, an astrophysicist at MIT, agreed. "The prospect of colonizing other planets is very far off, you must realize," he said.

Hawking's "work has been highly theoretical physics, not in astrophysics or global politics or anything like that," Winn added. "He is certainly stepping outside his research domain."

Hawking's comments Tuesday were reminiscent of the work of American astrophysicist Carl Sagan, who was a believer in the existence of extraterrestrial intelligence.

Sagan, a Cornell University professor and NASA-decorated scientist who died in 1996, noted that organic molecules, the kind that life on Earth is dependent on, appear to be almost everywhere in the solar system.

Sagan played a leading role in the U.S. space program, helping design robotic missions and contributing to the Mariner, Viking, Voyager and Galileo expeditions.

But his work also focused on the search for habitable worlds and intelligent life beyond the solar system, as well as theories about life's origins, ideas popularized in his best-selling 1985 novel, "Contact," which was made into a film starring Jodie Foster.

At Tuesday's news conference, Hawking said he too was venturing into the world of fiction. He plans to team up with his daughter, 35-year-old journalist and novelist Lucy Hawking, to write a children's book about the universe aimed at the same age group as the Harry Potter books.

"It is a story for children, which explains the wonders of the universe," said Lucy Hawking. They did not provide further details.

http://www.kurzweilai.net/news/frame.html?main=/news/news_single.html?id%3D5634

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"In a world that is in chaos politically, socially and environmentally, how can the human race sustain another 100 years?" -Stephen Hawking

Any of you genii or savants out there got an answer for Stephen? http://answers.yahoo.com/question/?qid=20060704195516AAnrdOD

http://biz.yahoo.com/ap/060707/people_hawking.html?.v=6

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Visualising invisibility
physorg.com, July 31, 2006

Invisibility has been an ingredient of myths, novels and films for millennia – from Perseus versus Medusa in Greek legend to James Bond’s latest car and Harry Potter’s cloak. A new study published today by the Institute of Physics reveals that invisibility is closer than we think.

The paper, Notes on conformal invisibility devices, published in the New Journal of Physics describes the physics of several theoretical devices that could create the ultimate illusion – invisibility.

“Objects are visible because they reflect light rays” says author Dr Ulf Leonhardt at St Andrews University, Scotland. “To be invisible, an object would have to let light pass through it, like H. G. Well’s Invisible Man. Alternatively light would have to bend around an object for it to be invisible. The ideas in this paper are based around devices that will bend light or radio waves around a hole inside the device. Any object placed inside the hole will become invisible. The light would flow round the hole like water around an obstacle.”

The bending of light is the cause of many optical illusions, such as mirages in the desert. Light bends in the hotter air near the ground in the desert and this causes a reflection of the sky on the ground – a mirage.

Dr Leonhardt went on to say “The devices work by bending light, as in a mirage. However, a mirage involves the reflection of light which produces the shiny image that can be seen: an invisibility device bends light without producing an image. To do this, the devices must have carefully designed refractive index profiles. The paper explains the physics and mathematics behind the devices using images rather than complex equations: it visualizes invisibility.”

The refractive index is a measure of the optical length that light has to travel in a medium: the higher the refractive index, the longer the optical path is to the light ray. Light rays bend when the refractive index of the medium they are travelling through varies. According to Fermat’s Principle of optical paths, light will follow the shortest optical path length. In the case of the mirage, air closer to the desert ground is hotter and has a lower refractive index than the cooler air higher up. Therefore light bends close to the desert floor in order to stay in the lower refractive index region.

Dr Leonhardt added “The next step is actually making one of these theoretical devices. There are advances being made in metamaterials that mean the first devices will probably be used for bending radar waves or the electromagnetic waves used by mobile phones. Such devices may be useful in wireless technology, for instance in protecting sensitive electronics from mobile-phone radiation in airplanes. After these have been developed, it is possible that devices that work for visible light are not too far behind.”

Abstract link: http://www.iop.org/EJ/abstract/1367-2630/8/7/118
Source: Institute of Physics
http://www.physorg.com/news73577617.html