Forumchem - Forum with AI(ALICE BOT & HAL9000) and TTS

Climate cycles persisting for millions of
years on ancient Mars left a record of rhythmic patterns in thick
stacks of sedimentary rock layers, revealed in three-dimensional detail
by a telescopic camera on NASA"s Mars Reconnaissance Orbiter.

Gamma-ray bursts (GRB) are the most powerful explosions known in the Universe; most originate in distant galaxies. A large percentage of bursts likely arise from the explosion of stars over 15 times more massive than our Sun. Experts believe that a burst from a nearby star could cause severe damage to the Earth’s protective ozone layer. All observed GRBs have originated from outside the Milky Way galaxy, although a related class of phenomena, soft gamma repeater flares, have been linked to magnetars within the Milky Way.

Scientists at NASA and the University of Kansas say that a mass extinction on Earth hundreds of millions of years ago could have been triggered by a star explosion called a gamma-ray burst. The scientists do not have direct evidence that such a burst activated the ancient extinction. The strength of their work is their atmospheric modeling -- essentially a "what if" scenario. The scientists believe GRB are the birth cries of black holes.

The scientists calculated that gamma-ray radiation from a relatively nearby star explosion, hitting the Earth for only ten seconds, could deplete up to half of the atmosphere"s protective ozone layer. Recovery could take at least five years. With the ozone layer damaged, ultraviolet radiation from the Sun could kill much of the life on land and near the surface of oceans and lakes, and disrupt the food chain.

Gamma-ray bursts are the most powerful explosions known. Most originate in distant galaxies, and a large percentage likely arise from explosions of stars over 15 times more massive than our Sun. A burst creates two oppositely-directed beams of gamma rays that race off into space.

Thomas says that a gamma-ray burst may have caused the Ordovician extinction 450 million years ago, killing 60 percent of all marine invertebrates. Life was largely confined to the sea, although there is evidence of primitive land plants during this period.

In the new work, the team used detailed computer models to calculate the effects of a nearby gamma-ray burst on the atmosphere and the consequences for life.

Thomas, with Dr. Charles Jackman of NASA"s Goddard Space Flight Center in Greenbelt, Md., calculated the effect of a nearby gamma-ray burst on the Earth"s atmosphere. Gamma rays, a high-energy form of light, can break molecular nitrogen  into nitrogen atoms, which react with molecular oxygen to form nitric oxide. More nitric oxide means more ozone destruction. Computer models show that up to half the ozone layer is destroyed within weeks. Five years on, at least 10 percent is still destroyed.

Next Thomas and fellow student Daniel Hogan, an undergraduate, calculated the effect of ultraviolet radiation on life. Deep-sea creatures living several feet below water would be protected. Surface-dwelling plankton and other life near the surface, however, would not survive.

This simulation image above shows the regions of the planet most susceptible to DNA damage (shown in red) if a large gamma ray burst were to occur close to Earth.

Though there is no direct evidence, scientists say a nearby gamma-ray burst may have caused the great extinction of the late Ordovician period 450 million years ago, which killed 60 percent of all marine invertebrates.

Dr. Bruce Lieberman, a paleontologist at the University of Kansas, originated the idea that a gamma-ray burst specifically could have caused the great Ordovician extinction, 200 million years before the dinosaurs. An ice age is thought to have caused this extinction. But a gamma-ray burst could have caused a fast die-out early on and also could have triggered the significant drop in surface temperature on Earth.

"One unknown variable is the rate of local gamma-ray bursts," said Thomas. "The bursts we detect today originated far away billions of years ago, before the Earth formed. Among the billions of stars in our Galaxy, there"s a good chance that a massive one relatively nearby exploded and sent gamma rays our way."

Swift launched in 2004 is a first-of-its-kind multi-wavelength observatory dedicated to the study of gamma ray burst (GRB) science. Its three instruments will work together to observe GRBs and afterglows in the gamma ray, X-ray, ultraviolet, and optical wavebands. Swift is designed to solve the 35-year-old mystery of the origin of gamma-ray bursts.

Posted by Casey Kazan.

Image credit: Credit: NASA/U. of Kansas

http://www.nasa.gov/centers/goddard/news/topstory/2005/gammaray_extinction.html

http://www.nasa.gov/centers/goddard/news/topstory/2005/gammaray_extinction.html

In further proof that NASA are cooler than most people manage without liquid hydrogen, they"ve started analyzing a meteorite - on Mars.  This scores them a double "Space Stuff" bonus, and proves that no matter how incredible things get, the universe always has more to offer.

The Opportunity rover (still running after five years despite being built for ninety-day mission) made the mega-Martian discovery when it spotted "Block Island" - a half-meter chunk of rock absolutely nothing like anything anywhere else on the planet so far.  Because it probably isn"t from the planet, with scientists saying it"s a meteor which made Mars its final resting place.

Opportunity will examine this second-order spacerock with its alpha-particle X-ray spectrometer to see what it"s made of, and therefore where it came from.  Those worried about the science-fiction effects of bathing an other-worldly artifact in radiation from such a polysyllabic device should remember that
a)  This is science, not fiction
b)  It"s on Mars anyway.  If we do release some extraplanetary horror we"re got a few hours to hire Bruce Willis.

That this happened at all is a triumph of human curiosity, coincidence, and extremely well put together space engineering: three factors we"re going to need to become what we can.  Here"s hoping we keep up the effort in future space scheduling.

Opportunity to examine "Block Island"

Scientists have been up to their space-examining tricks again, looking eleven-billion light-years away and wondering "What"s going on over there?"  And since it affects how the universe began and everything that"s been happening since, you should wonder too.  They"ve spotted super-squeezed, massive, high speed galaxies - and they don"t know why.

The first factor is that eleven billion light-years away means eleven billion years ago, which is nearly as much ago as there is.  The universe is only about fourteen billion years old meaning that these early observations tell us about early universal conditions.  The intense galaxies observed so far cram the mass of a "modern" galaxy into one fifth of the size, and are spinning four times faster than the Milky Way (accounting for differing radii). 

What happened to these turbo-galaxies?  The leading theory is that if those existed then, and these big slow ones exist now, then they must have simply expanded until they became what we see today.  Except you don"t get to use "simply" saying things about cosmological evolution, and nobody can explain exactly how things turned from one to the other - or how they formed in the first place.

The data was gathered by scientists of Yale University, using the GEMINI telescope and the Hubble satellite, and soon they"ll be able to examine more closely.  Both systems are now upping their abilities: Hubble recently unveiled a new Wide Field Camera and GEMINI is off undergoing upgrades as you read.  Increased ability to observe things near the edge of everything, in both space and time, will mean we better understand how things happened. 

Luke McKinney

Hyperactive Galaxies in the Early Universe

nbsp;

Imagine a planet dominated by cities like Mega-City One, a megalopolis of over 400 million people across the east coast of the United States, featured in the Judge Dredd comic or "San Angeles,"nbsp; formed from the joining of Los Angeles, Santa Barbara, San Diego, and the surrounding metropolitan regions following a massive earthquake featured in the 1993 movie "Demolition Man."

Don"t hold your breath: the 21st century will soon have 19 cities with populations of 20 million or more.

The history of the human species is a history of migration.
In 1000 A.D. Cordova, Spain was the largest city. By 1500, Bejing began its rise to power, and 300 years later it was the first city to be over
a million people. By 1900 London emerged the world"s supercity with over
6 million people. In 1950 New York was proclaimed the first
"megacity" with a population of over 10 million people in the greater
metropolitan area.

How is increasing mass urbanization affecting the quality of life? 1.4
million people are moving into cities each week. How will this vast migration change the way we live and die; how we treat the elderly, the poor, the
way work, trade, learn, the way we eat, consume, recycle, power, engineer,
innovate?

"While some say the world is flat, supercities are rising - vast, intensely urban hubs will radically redefine the world"s future macroeconomic and cultural landscape. Most of the world"s population right now lives and works in cities. Many more will. It"s critical to gain a truer understanding of what"s happening: the rise of supercities is the defining megatrend of the 21st century," says futurist Richard Saul Wurman, founder of the TED Conference and 19 20 21.org -devoted to the effect of mass urbanization on the planet.

In 1800 only 3% of the world"s population lived in cities; 47% by
the end of the twentieth century. In 1950, there were 83 cities with
populations exceeding one million; by 2007, this had risen to 468 urban areas of more than one million.

If the current trend continues, the
world"s urban population will double every 38 years. The UN forecasts
that today"s urban population of 3.2 billion will rise to nearly 5
billion by 2030, when three out of five people will live in cities. By 2050 two-thirds of the world’s population will live in cities, up
from about 50% right now.

The world’s population of “slum” dwellers increases by 25 million every year. The majority of these numbers come from the fringes of urban margins, located in legal and illegal settlements with insufficient housing and sanitation. This has been caused by the massive migration, both internal and transnational, into cities.

The greatest population increase will be most dramatic in the poorest and least-urbanized
continents, Asia and Africa. Surveys and projections indicate that all
urban growth over the next 25 years will be in developing countries, where one billion people, one-sixth of the world"s population, now live in slum-level conditions -breeding grounds for crime, drug addiction, alcoholism, poverty and
unemployment. By 2030, over 2 billion people in the world
will be living in these mega-ghettoes.

In the video below Jon Kamen describes the impact of the rise of the cities in a" flat world." It"s a fascinating, if not a pretty picture.

Posted by Casey Kazan.

In 1964, astrophysicists in Fred Hoyle"s scifi novel, The Black Cloud, become aware of an immense black cloud of gas that enters the solar system. The cloud, moving to interpose itself between the sun and the earth, could wipe out most of the life on earth by blocking solar radiation and ending photosynthesis. Astronomers and other scientists gather in England, where they discover that the cloud is a super-organism, many times more intelligent than our human species.

Hoyle"s Black Cloud  lives in the vacuum of space held together by electric and magnetic interactions, lives in the vacuum of space and is composed of dust-grains instead of cells. It derives its energy from gravitation or starlight, and acquires chemical nutrients from the naturally occurring interstellar dust. The cloud has a network of long-range electromagnetic signals that transmit information and coordinate its activities, much like our nervous system. Like silicon-based life and unlike water-based life, the Black Cloud can adapt to arbitrarily low temperatures of a cold universe, making it immortal, impervious to the eventual death of a star.

In his essay, "Is Life Analog or Digital?" Freeman Dyson of the Princeton Institute for Advanced Studies suggests that "an analog form of life, such as Hoyle"s black cloud, adapts better to low temperatures, because a cloud with a fixed number of grains can expand its memory without limit by increasing its linear scale."

In a fascinating case of life imitating art, physicists have discovered over the apst few years intriguing evidence of life-like double-helix structures formed from inorganic substances in space which raises the question of  whether extraterrestrial life could be composed of corkscrew-shaped formations of interstellar dust. The findings hint at the possibility that life beyond Earth may not necessarily use carbon-based molecules as its building blocks and they may also point to a possible new explanation for the origin of life on Earth.

The international team has discovered that under the right conditions, particles of inorganic dust can become organized into helical structures. These structures can then interact with each other in ways that are more usually associated with organic compounds and life itself.

Led by V.N. Tsytovich of the Russian Academy of Science and the Max-Planck Institute for Extraterrestrial Physics and the University of Sydney, the team studied the behavior of complex mixtures of inorganic materials in a plasma.

However, using a computer simulation of molecular dynamics, Tsytovich and his colleagues demonstrated that particles in a plasma can undergo self-organization as electronic charges become separated and the plasma becomes polarized. This effect results in microscopic strands of solid particles that twist into corkscrew shapes, or helical structures resembling DNA. These helical strands are themselves electronically charged and are attracted to each other.

Tsytovich reported they can divide to form two copies of the original structure and can also interact to induce changes in their neighbors. They can even evolve into yet more structures as less stable ones break down, leaving behind only the "fittest" structures in the plasma.

Could helical clusters formed from interstellar dust be somehow alive? "These complex, self-organized plasma structures exhibit all the necessary properties to qualify them as candidates for inorganic living matter," muses Tsytovich, "they are autonomous, they reproduce and they evolve." He added that the plasma conditions needed to form these helical structures are common in outer space.

Plasmas can also form under terrestrial conditions, such as the point of a lightning strike. The researchers speculate that perhaps an inorganic form of life emerged on the primordial earth, which then acted as the template for the more familiar organic molecules we know today.

Posted by Casey Kazan.

Sources: Institute of Physics
http://www.edge.org/3rd_culture/dyson_ad/dyson_ad_index.html

BL Lacertae is a blazar, a supermassive galactic-core black hole
emitting vast and variable beams of energy.  Please understand that
giving this thing a name like "blazar" is like calling a speeding
sixteen wheeler truck full of professional wrestlers, grizzly bears and
dynamite a "gentle prodder." The English language simply lacks the
ability to get across the staggering scale of these events - because it
doesn"t have a case above upper or letters bigger than capital.  You
can try writing down the values as numbers, but they end up being so
stupidly huge that our monkey brains, programmed to deal with "one two
three lots", just don"t comprehend them.

This image of the Victoria Impact Crater in the Meridiani Planum region of Mars was taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA"s Mars Reconnaissance Orbiter at more of a sideways angle than earlier orbital images of this crater. The camera pointing was 22 degrees east of straight down, yielding a view comparable to looking at the landscape out an airplane window. The crater is named after Victoria -one of the five ships of Ferdinand Magellan and the first ship to circumnavigate the globe . Along the edges of the crater are many outcrops within recessed alcoves and promontories, named for bays and capes that Magellan discovered. Opportunity traveled for 21 months to Victoria before finally reaching its edge on September 26, 2006.

This view is a cutout from a HiRISE exposure taken on July 18, 2009. Some of Opportunity"s tracks are still visible to the north of the crater (left side of this cutout). Image Credit: NASA/JPL-Caltech/University of Arizona