Replies to post #146 on Extraterrestrial

[SeriousMoney]

According to Ray Kurzweil & his law of accelerating returns, Hawkings may be behind the curve, so to speak.

http://en.wikipedia.org/wiki/Law_of_Accelerating_Returns

http://www.kurzweilai.net/articles/art0134.html?printable=1

[SeriousMoney]

Kurzweil is also optimistic about radical life extension. "I expect that within 15 years, we'll be adding more than a year each year to remaining life expectancy. So my advice is: take care of yourself the old-fashioned way for a while longer and you may get to experience the remarkable century ahead."

http://www.kurzweilai.net/news/frame.html?main=/news/news_single.html?id%3D5644

[SeriousMoney]

Mysterious quasar casts doubt on black holes
18:21 27 July 2006
NewScientist.com news service
David Shiga



The hole in the disc of matter in quasar Q0957+561 shown in this artist's impression could be the sign of an exotic compact object called a MECO (Image: Christine Pulliam/CfA)A controversial alternative to black hole theory has been bolstered by observations of an object in the distant universe, researchers say. If their interpretation is correct, it might mean black holes do not exist and are in fact bizarre and compact balls of plasma called MECOs.

Rudolph Schild of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, US, led a team that observed a quasar situated 9 billion light years from Earth. A quasar is a very bright, compact object, whose radiation is usually thought to be generated by a giant black hole devouring its surrounding matter.

A rare cosmological coincidence allowed Schild and his colleagues to probe the structure of the quasar in much finer detail than is normally possible. Those details suggest that the central object is not a black hole. "The structure of the quasar is not at all what had been theorised," Schild told New Scientist.

A black hole, as traditionally understood, is an object with such a powerful gravitational field that even light is not fast enough to escape it. Anything that gets within a certain distance of the black hole's centre, called the event horizon, will be trapped.

A well accepted property of black holes is that they cannot sustain a magnetic field of their own. But observations of quasar Q0957+561 indicate that the object powering it does have a magnetic field, Schild's team says. For this reason, they believe that rather than a black hole, this quasar contains something called a magnetospheric eternally collapsing object (MECO). If so, it would be best evidence yet for such an object.

Flickering clues

The researchers used gravitational lensing to make their close observation of the quasar. This technique exploits rare coincidences that can occur when a galaxy sits directly between a distant object and observers on Earth.

The gravity of the intervening galaxy acts like a lens. As the intervening galaxy's individual stars pass in front of the quasar, this bending varies, making the quasar appear to flicker.

Carefully scrutinising this flickering allowed the researchers to probe fine details of the quasar's structure that are normally far too small to be resolved by even the most powerful telescopes.

Magnetic sweep

The researchers found that the disc of material surrounding the central object has a hole in it with a width of about 4000 Astronomical Units (1 AU is the distance between the Earth and the Sun). This gap suggests that material has been swept out by magnetic forces from the central object, the researchers say, and must therefore be a MECO, not a black hole.

"I believe this is the first evidence that the whole black hole paradigm is incorrect," says Darryl Leiter of the Marwood Astrophysics Research Center in Charottesville, Virginia, US, who co-authored the study. He says that where astronomers think they see black holes, they are actually looking at MECOs.

According to the MECO theory, objects in our universe can never actually collapse to form black holes. When an object gets very dense and hot, subatomic particles start popping in and out of existence inside it in huge numbers, producing copious amounts of radiation. Outward pressure from this radiation halts the collapse so the object remains a hot ball of plasma rather than becoming a black hole.

Extremely complex

But Chris Reynolds of the University of Maryland, in College Park, US, says the evidence for a MECO inside this quasar is not convincing. The apparent hole in the disc could be filled with very hot, tenuous gas, which would not radiate much and would be hard to see, he says. "Especially if you're looking with an optical telescope, which is how these observations were made, you wouldn't see that gas at all," he told New Scientist.

Leiter says this scenario would leave other things unexplained, however. The observations show that a small ring at the inner edge of the disc is glowing, which is a sign that it has been heated by a strong magnetic field, he says. In Reynolds's scenario, one would expect a much broader section of the disc to be heated, he says.

In any case, says Reynolds, it is difficult to draw conclusions from the team's detailed comparisons of their observations with models of black holes because those models are far from definitive. "We know the accretion of gas into black holes is an extremely complex phenomenon," he says. "We don’t know precisely what that would look like."

"It would be truly exciting if there was compelling evidence found for a non-black-hole object in these quasars," Reynolds adds. "I just don't think that this fits."

Journal reference: The Astronomical Journal (vol 132, p 420)

http://www.newscientistspace.com/article/dn9620-mysterious-quasar-casts-doubt-on-black-holes.html

[SeriousMoney]

Reverse-engineering the brain... or "Way of the Borg?

Nanowire arrays can detect signals along individual neurons
Merger of nanowires and neurons could boost efforts to measure and understand brain activity
By Steve Bradt
FAS Communications

Opening a whole new interface between nanotechnology and neuroscience, scientists at Harvard University have used slender silicon nanowires to detect, stimulate, and inhibit nerve signals along the axons and dendrites of live mammalian neurons.

Harvard chemist Charles M. Lieber and colleagues report on this marriage of nanowires and neurons this week in the journal Science.

"We describe the first artificial synapses between nanoelectronic devices and individual mammalian neurons, and also the first linking of a solid-state device -- a nanowire transistor -- to the neuronal projections that interconnect and carry information in the brain," says Lieber, the Mark Hyman Jr. Professor of Chemistry in Harvard's Faculty of Arts and Sciences and Division of Engineering and Applied Sciences. "These extremely local devices can detect, stimulate, and inhibit propagation of neuronal signals with a spatial resolution unmatched by existing techniques."

Electrophysiological measurements of brain activity play an important role in understanding signal propagation through individual neurons and neuronal networks, but existing technologies are relatively crude: Micropipette electrodes poked into cells are invasive and harmful, and microfabricated electrode arrays are too bulky to detect activity at the level of individual axons and dendrites, the neuronal projections responsible for electrical signal propagation and interneuron communication.

By contrast, the tiny nanowire transistors developed by Lieber and colleagues gently touch a neuronal projection to form a hybrid synapse, making them noninvasive, and are thousands of times smaller than the electronics now used to measure brain activity.

Lieber's group has previously shown that nanowires can detect, with great precision, molecular markers indicating the presence of cancer in the body, as well as single viruses. The group's latest work takes advantage of the size similarities between ultra-fine silicon nanowires and the axons and dendrites projecting from nerve cells: Nanowires, like neuronal offshoots, are just tens of nanometers in width, making the thin filaments a good match for intercepting nerve signals.

Because the nanowires are so slight -- their contact with a neuron is no more than 20 millionths of a meter in length -- Lieber and colleagues were able to measure and manipulate electrical conductance at as many as 50 locations along a single axon.

The current work involves measurement of signals only within single mammalian neurons; the researchers are now working toward monitoring signaling among larger networks of nerve cells. Lieber says the devices could also eventually be configured to measure or detect neurotransmitters, the chemicals that leap synapses to carry electrical impulses from one neuron to another.

"This work could have a revolutionary impact on science and technology," Lieber says. "It provides a powerful new approach for neuroscience to study and manipulate signal propagation in neuronal networks ata level unmatched by other techniques; it provides a new paradigm for building sophisticated interfaces between the brain and external neural prosthetics; it represents a new, powerful, and flexible approach for real-time cellular assays useful for drug discovery and other applications; and it opens the possibility for hybrid circuits that couple the strengths of digital nanoelectronic and biological computing components."

Lieber's co-authors on the Science paper are Fernando Patolsky, Brian P. Timko, Guihua Yu, Ying Fang, Andrew B. Greytak, and Gengfeng Zheng, all of Harvard's Department of Chemistry and Chemical Biology. Their work was supported by the Defense Advanced Research Projects Agency and Applied Biosystems.

http://www.news.harvard.edu/gazette/2006/08.24/99-nanowire.html