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Friday, September 12, 2008

'Galactic internet' proposed

Aliens might have sent messages by tweaking variable stars.

galaxyGalaxy NGC 1309, snapped by the Hubble Space Telescope, is packed with Cepheid stars of the type that could form a communication network.NASA, The Hubble Heritage Team and A. Riess (STScI)

Just by gazing at the stars, earthling astronomers might have unwittingly picked up broadcasts from extraterrestrial civilizations. So says a neutrino physicist, adding that it might take researchers just a few months of searching to find evidence of this alien internet.

John Learned at the University of Hawaii in Honolulu and his colleagues think that signals could be sent by manipulating Cepheid variable stars. These rare stars can be seen in other galaxies more than 60 million light years from our own.

Cepheids dim and brighten regularly, in a pattern that depends on their brightness. This lets astronomers measure the distance to the stars, helping to resolve mysteries such as the Universe's age and how fast it is expanding. As such, any sufficiently advanced civilization would want to monitor such stars, the scientists reasoned.

To send messages using a Cepheid, Learned and his colleagues suggest that extraterrestrials might change the star's cycle. A Cepheid becomes dimmer as ionized helium builds up in its atmosphere. Eventually, the atmosphere expands and deionizes, restarting the cycle.

Firing a high-energy neutrino beam into a Cepheid could heat its core and brighten the star early — "just as an electric pulse to the heart can make it skip a beat," Learned says.

The neutrinos could be made by blasting a proton beam at a target — sapphire, carbon or tungsten would work, says Learned. The target produces subatomic particles, mostly pions, which decay to produce neutrinos.

The normal and shortened pulses could be used to encode data, to form what the researchers call a 'galactic Internet' in a paper posted to the arXiv preprint server1.

Low bandwidth

"It's an interesting idea that can be tested — somebody should look at the archives on these stars and see if there are any light variations of the kind they are describing," says physicist Freeman Dyson of the Institute for Advanced Study in Princeton, New Jersey.

Adds Seth Shostak, senior astronomer at the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California: "It's a great idea, reminiscent of an old Russian idea about bouncing high-energy radiation off the 100 or 200 real supergiant stars in the galaxy to generate anomalous radiation as signals others could see."

Learned admits that the galactic internet would be slow — a Cepheid with a roughly one-day period could transmit about 180 bits per year. Such a transmission would require roughly a millionth of the star's energy, the researchers estimate.

"A millionth of a star's output is a heck of a lot of energy," says Shostak, adding that a high-powered radio beacon could probably transmit more data over similar distances.

Learned says that finding a signal from the galactic internet is a long shot — but, he says, we've got 100 years of data on Cepheids in which to look.

"Analyzing that data would take a graduate student a couple of months, and just think if it turned out to be correct," says Learned. "The implications would be astounding."

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The Yin-Yang of Ultraviolet Radiation

By Lynn J. Rothschild
Research Scientist, NASA Ames Research Center

Now that we have passed through summer, replete with warnings about the health hazards of exposure to ultraviolet radiation, the subdued light of autumn provides the ambiance in which to take a more balanced look at what UV radiation has meant to life on Earth. We need UV radiation to synthesize vitamin D, which is critical for calcium absorption. UV radiation is used by some organisms as an environmental cue, and it aids in some repair mechanisms for DNA damage. Further, UV-catalyzed reactions in the atmosphere and on the early Earth were critical to providing the conditions for life to arise. But the fact remains: UV radiation itself is hazardous to carbon-based life such as ours. Why should this be so, and how has life overcome this obstacle to thrive on Earth?

The apparent diversity of organisms masks the fact that all life on Earth, and possibly in the universe, is based primarily on a few types of organic compounds. Principal among these are proteins and nucleic acids (RNA and DNA), respectively the primary structural and hereditary components of terrestrial biology. Unfortunately, the maximum absorption of radiation for both compounds is in the UV portion of the solar spectrum, 280 nm for proteins and approximately 260 nm for nucleic acids, and such absorption could destroy these molecules. While solar radiation below about 290 nm does not reach the surface of the Earth today, it is still dangerously close to these peak absorptions.

If this weren't enough, UV radiation can catalyze the production of reactive oxygen species, such as the hydroxyl radical, which themselves damage organic compounds. And the situation was far worse on early Earth, prior to the formation of a protective ozone shield. Without the ozone shield (but with CO2 in the atmosphere, which we have had from the earliest times), we would be bathed in UV radiation down to 200 nm — a horrifically dangerous situation for life.

Natural sunscreens

With this background, one might forgive an extraterrestrial biologist from assuming that all life on Earth seeks refuge underground. But yet we know this not to be universally true. In fact, life underground is at a disadvantage as it cannot access other portions of the solar spectrum, specifically the longer wavelengths that bacteria, algae and plants exploit for photosynthesis and we animals use for vision.

A common evolutionary solution to this problem is to produce biological "sunscreens" for protection from UV radiation while allowing access to the longer wavelengths, and indeed many organisms from prokaryotes to humans use this approach. But it is also possible to exploit minerals that are transparent to longer wavelengths, but attenuate UV radiation. My lab has found that organisms that live under sand grains do just that, as do organisms that live in salt crusts such as the ones in San Francisco Bay's Cargill Salt Company. In collaboration with SETI Institute Principal Investigator Janice Bishop, and under the auspices of an NAI grant to the SETI Institute, we are exploring the possibility that iron-based compounds were particularly important in protecting the earliest organisms on Earth.

Why iron? Iron is one of the most abundant metals in the universe, found in stars such as our sun, in planets, and as a principal constituent of certain types of meteorites and asteroids known as iron meteorites and M-type asteroids. On Earth it accounts for about 5.6% of the crust, and nearly the entire core. Iron is arguably the most important metal for life because of its role in many metabolic processes, including being the critical component of hemoglobin, the compound that transports oxygen in red blood cells.

Near the surface of the ocean, iron concentrations exist in the nanomolar to picomolar range. But the iron compounds that are there, for example nanophase ferric oxides/oxyhydroxides, are capable of absorbing UV radiation. Thus, we have proposed that such compounds allowed early organisms to become photosynthetic — on the one hand, the iron compounds were available for use in metabolism, while on the other they attenuated harmful UV radiation while transmitting the longer wavelengths needed for photosynthesis. Through combining our expertise in biology and geochemistry, and through lab and field work, we plan to test this hypothesis in the coming years.

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Satellite That Predicts Climate Change About to Launch

World's Top Scientists Ponder: What If The Whole Universe Is, Like, One Huge Atom?

PALO ALTO, CA—Gathering for what members of the international science community are calling "potentially the most totally out-to-lunch freaky head trip since Einstein postulated that space and time were, like, curved and shit," a consortium of the world's top physicists descended upon Stanford University Monday to discuss some of the difficult questions facing the cutting edge of theoretical thinking.

Enlarge Image World's Top

Cal Tech physicist Dr. Jonathan Friedrich postulates a bunch of freaky shit that makes his colleagues' heads spin right the hell off.

Among the revolutionary ideas expected to be raised at the historic week-long summit is the possibility that, like, our whole friggin' universe might be just one big atom in, say, some super-duper huge thing out there somewhere, or something.

"Whoa, man," Dr. Jacob "The Boz" Bozeman of MIT told reporters. "The implications of this deceptively simple hypothesis are, like, completely blowing my mind. Like, we could all be nothing more than this little dot in the fingernail of some huge-ass giant dude. Or maybe a seed in the mustard of, like, some really big sandwich, or even a germ on the back of a flea that's, like, sitting on a hair on some giant dog's ass. Truly, it boggles the freakin' mind, man. It freaks me the fuck right out."

The universe-as-possible-giant-atom theory originated in May with a team of Cal Tech particle physicists, who developed the theory late one night while sitting around on a couch in the Physics Department's cyclotron and foosball facility, "just shooting the shit." The theory, which was reportedly conceived after the group became highly engrossed in ceiling-tile patterns for several minutes while waiting for a pizza to arrive, is said to be so advanced that only a few scientists in the world even have their heads together enough to really, you know, deal. Yet even among this elite group, many are said to be "seriously thrown for a loop" by its implications.

"I'm like, 'Whoa there, man, slow down,'" said Dr. Dieter Gerhardt, a low-temperature physicist at Cornell University. Pausing for a moment to collect himself, the renowned scientist then placed his hands on his forehead before extending them outward in a sweeping gesture and making a buzzing "space-noise" sound effect with his lips, non-verbally indicating the degree to which his mind was blown by the whole freaky deal.

Among other topics to be explored at the Stanford conference, according to Bozeman: the concept of parallel, or "alternate," Earths; the theory of multi-dimensional "superstrings" that fold backward and forward throughout the fabric of the universe; and "a whole bunch of other shit I totally can't even handle thinking about right now."

On Monday, the most high-profile conference attendee, Cambridge's Dr. Stephen Hawking, discussed his recent research exploring the possible existence of "sideways," or lateral, time, a concept most scientists in attendance described as "way out there."

"I don't want to fuck with anybody's head here," Hawking told the assembled scientists via his voice-simulation device, "but if time goes sideways as well as forward, there might be, like, other versions of this reality, where, say, the Roman Empire is still in charge and stuff."

"By the way," Hawking added, "ever think about what'd happen if you, say, went back in time and accidentally killed your own younger self? Man, that shit would be so fucked up."

Hawking's ideas provoked strong reaction. "I remember I was pretty wigged out when Feynman came up with that shit about antiparticles just being normal particles traveling backwards in time," said Dr. Wei Lo-Huang of Princeton. "That was heavy enough to have to deal with. But now Hawking comes up with this? What is with that?"

"Fuck, man... if this turns out to be true, it will require a total recalibration of all our methods for measuring space-time flux, and that means all my old equations are gonna be, like, for shit," Wei said. "Aw, man."

Though Hawking's lateral-time theory may prove significant, most scientists in attendance said they plan to avoid it for now, explaining that the "whole one big atom deal" (or "WOBAD" theory, as it has come to be known within physics circles) is more than enough to completely freak their shit, and that they would prefer to take these mind-blowing questions one at a time, just so they don't completely, you know, lose it.

"I totally can't get with where my head is at, if you dig what I'm saying," said Dr. Sanjay Gupta, renowned for his work in advanced quantum hydroponics theory. "It's like, one big atom? Forget about it, man. Even weirder is, like, if we're just one big atom in a larger universe, how do we know all the little atoms don't have, you know, little universes in them, with, like, little people living on them, with little cars and little houses, and maybe even itsy-bitsy tiny-ass international symposiums on cutting-edge theoretical physics, even."

"That shit would be too much," Gupta said. "It'd be like that Dr. Seuss book Horton Hears A Who and shit. I read that when I was, like, six, and it totally weirded me out."

"Say, can I get another handful of those chips, dude?" Gupta asked.

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Fermilab Looks for Visitors from Another Dimension

By Mark Alpert

Neutrino Hunters Bonnie Fleming and Mitchell Soderberg inspect a prototype liquid-argon detector called ArgoNeuT that will pave the way for the MicroBooNE facility at Fermilab.
Fermilab

The detection of extra dimensions beyond the familiar four—the three dimensions of space and one of time—would be among the most earth-shattering discoveries in the history of physics. Now scientists at the Fermi National Accelerator Laboratory in Batavia, Ill., are designing a new experiment that would investigate tantalizing hints that extra dimensions may indeed exist.

Last year researchers involved in Fermilab’s MiniBooNE study, which detects elusive subatomic particles called neutrinos, announced that they had found a surprising anomaly. Neutrinos, which have no charge and very little mass, form out of nuclear reactions and particle decays. They come in three types, called flavors—electron, muon and tau—and oscillate wildly from one flavor to another as they travel along. While observing a beam of muon neutrinos generated by one of Fermilab’s particle accelerators, the MiniBooNE researchers found that an unexpectedly high number of the particles in the low-energy range (below 475 million electron volts) had transformed into electron neutrinos. After a year of analysis, the investigators have failed to come up with a conventional explanation for this so-called low-energy excess. The mystery has focused attention on an intriguing and very unconventional hypothesis: a fourth kind of neutrino may be bouncing in and out of extra dimensions.

String theorists, who seek to unify the laws of gravity with those of quantum mechanics, have long predicted the existence of extra dimensions. Some physicists have proposed that nearly all the particles in our universe may be confined to a four-dimensional “brane” embedded within a 10-dimensional “bulk.” But a putative particle called the sterile neutrino, which interacts with other particles only through gravity, would be able to travel in and out of the brane, taking shortcuts through the extra dimensions. In 2005 Heinrich Päs, now at the University of Dortmund in Germany, Sandip Pakvasa of the University of Hawaii and Thomas J. Weiler of Vanderbilt University predicted that the extradimensional peregrinations of sterile neutrinos would increase the probability of flavor oscillations at low energies—exactly the result found at MiniBooNE two years later.

Energized by the prospect of discovering new laws of physics, the MiniBooNE team soon proposed a follow-up experiment called MicroBooNE that could test the sterile neutrino hypothesis. The new detector, a cryogenic tank filled with 170 tons of liquid argon, would be able to detect low-energy particles with much greater precision than its predecessor could. A particle emerging from a neutrino interaction would ionize the argon atoms in its path, inducing currents in arrays of wires at the perimeter of the tank. Scientists could then pinpoint the trajectory of the particle, allowing them to better distinguish between electron neutrino interactions and other events and thus determine whether there really is an excess of oscillations at low energies.

Estimated to cost about $15 million, the MicroBooNE tank would be located near the MiniBooNE detector at Fermilab so that it could observe the same beam of neutrinos. This past June the lab’s physics advisory committee approved the design phase for the project; if all goes well, the detector could begin operating as soon as 2011.

Researchers hope that MicroBooNE will lead to the development of much larger detectors, containing hundreds of thousands of tons of liquid argon in tanks as big as sports arenas. Such facilities could search for other hypothesized phenomena such as the extremely rare decay of protons. “It’s a fantastic new technology,” says Bonnie Fleming, a physicist at Yale University and spokesperson for MicroBooNE. “And it’s crucial for taking the next step in physics.”

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