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Wednesday, December 10, 2008

Scientists: Space Lasers Could Measure Atmospheric Carbon Dioxide

Proof that Albert Einstein's black holes do exist, claim scientists

By Richard Alleyne, Science Correspondent

Milky Way: the team proved the existence of black holes by tracking the motions of 28 stars circling around the Milky Way
The team proved the existence of black holes by tracking the motions of 28 stars circling around the Milky Way Photo: PA

Ever since Albert Einstein came up with his general theory of relativity, black holes has been central to our knowledge of the Universe.

Now experts say they have shown that the theoretical phenomenon, whose gravitational pull is thought to hold galaxies together, exist "beyond any reasonable doubt".

The team of scientists spent 16 years studying the existence of a super massive black hole thought to be at the centre of our galaxy, the Milky Way.

While the black hole itself is invisible to the eye, the team proved its existence by tracking the motions of 28 stars circling around it.

Just as swirling leaves caught in a gust of wind can provide clues about air currents, so the stars' movements reveal information about forces at work at the galactic centre.

The observations show that the stars orbit a central concentration of mass four million times greater than that of the Sun, claim the team from the Max-Planck Institute for Extraterrestrial Physics in Garching, near Munich, Germany.

"Undoubtedly the most spectacular aspect of our long term study is that it has delivered what is now considered to be the best empirical evidence that super-massive black holes do really exist," said study leader Professor Reinhard Genzel.

"The stellar orbits in the galactic centre show that the central mass concentration of four million solar masses must be a black hole, beyond any reasonable doubt."

The astronomers were also able to measure with great accuracy how far the Earth is from the centre of the galaxy - a distance of 27,000 light years.

Usually the central region of the Milky Way is hard to see because the view from Earth is blocked by interstellar dust.

To overcome this problem, the astronomers, who published their findings in the Astrophysical Journal, focused on infrared light wavelengths that can penetrate the dust clouds.

The galaxy's central mass, long suspected of being a giant black hole, is known as "Sagittarius A star".

The European Southern Observatory study, which began in 1992, was made using the 3.5 metre (11ft) New Technology Telescope at the La Silla observatory and the Very Large Telescope - an array of four 8.2 metre (26ft) telescopes at the Paranal observatory. Both operate from the Atacama desert in Chile.

The team, who found that one particular star made a full orbit of the black hole in the 16 year study, now hope to use even more powerful telescopes to further test Einstein's theories.

A black hole is a theoretical region of space in which the gravitational field is so powerful that nothing, not even electromagnetic radiation (visible light), can escape its pull. They are believed to be the remnants of burnt out suns.

While the idea of a black hole dates back as far as 1783, it was only after Einstein published his general relativity theory in 1916 that the modern concept was introduced by the German physicist Karl Scharzchild. The actual phrase black hole was not, however, coined until 1968.

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Black hole confirmed in Milky Way

By Pallab Ghosh

Core of the Milky Way galaxy, taken with Nasa's Spitzer space telescope
The Milky Way was tracked from an observatory in Chile

There is a giant black hole at the centre of our galaxy, a study has confirmed.

German astronomers tracked the movement of 28 stars circling the centre of the Milky Way, using two telescopes in Chile.

The black hole is four million times more massive than our Sun, according to the paper in The Astrophysical Journal.

Black holes are objects whose gravity is so great that nothing - including light - can escape them.

According to Dr Robert Massey, of the Royal Astronomical Society (RAS), the results suggest that galaxies form around giant black holes in the way that a pearl forms around grit.

'The black pearl'

Dr Massey said: "Although we think of black holes as somehow threatening, in the sense that if you get too close to one you are in trouble, they may have had a role in helping galaxies to form - not just our own, but all galaxies.

The most spectacular aspect of our 16-year study, is that it has delivered what is now considered to be the best empirical evidence that super-massive black holes do exist
Professor Reinhard Genzel
Head of the research team

"They had a role in bringing matter together and if you had a high enough density of matter then you have the conditions in which stars could form.

"Thus the first generation of stars and galaxies could have come into existence".

The researchers from the Max Planck Institute for Extraterrestrial Physics in Germany said the black hole was 27,000 light years, or 158 thousand, million, million miles from the Earth.

"Undoubtedly the most spectacular aspect of our 16-year study, is that it has delivered what is now considered to be the best empirical evidence that super-massive black holes do really exist," said Professor Reinhard Genzel, head of the research team.

"The stellar orbits in the galactic centre show that the central mass concentration of four million solar masses must be a black hole, beyond any reasonable doubt."

Observations were made using the 3.5m New Technology Telescope and the 8.2m Very Large Telescope (VLT) in Chile. Both are operated by the European Southern Obsevatory (Eso).

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With Treats, Dogs Seem to Know What's Fair

By HENRY FOUNTAIN

To the list of the qualities of dogs — enthusiastic and steadfast come to mind — can be added another. That pooch of yours, researchers say, may be envious.

Scientists in Austria report in The Proceedings of the National Academy of Sciences that a dog may stop obeying a command if it sees that another dog is getting a better deal.

In this way dogs may be showing a sensitivity that is similar to, although perhaps more primitive than, that shown by chimpanzees and some monkeys. Until now those primates were the only nonhumans to show what is called “inequity aversion” in the absence of a reward.

The finding may come as no surprise to some dog owners, and it didn’t completely surprise Friederike Range, a postdoctoral researcher at the University of Vienna who led the study.

“We have a dog at home,” she said, “and I know how jealous she is of different people and situations.”

The study tried to quantify the behavior by using well-trained dogs that readily offer a paw on command. The researchers used two dogs side by side but treated them differently, giving one a better reward (sausage) and the other a lesser one (bread) when the paw was given, or giving one dog no reward at all.

They found that the quality of the reward made little difference. But in the case in which one dog got no treat at all, that dog became less and less inclined to obey the command.

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Fire Ants Win Out Through Land Changes, Not a Better Build

Walter R. Tschinkel

A nest of fire ants, “disturbance specialists,” in Tallahassee, Fla.

Fire ants love a disturbance. Plow up some ground just about anywhere in the South, and chances are the red imported fire ant, Solenopsis invicta, will take over from native ant species. That’s why S. invicta, a major invasive pest, is found in subdivisions, shopping centers and other areas where the natural environment has been disturbed.

But is it the human-caused disturbance that makes S. invicta have such a negative impact on other ants, or something about the ant itself? One school of thought holds that the reason many invasive species succeed is that they are superior to other species and can outcompete them no matter what the situation.

A large study by Joshua R. King and Walter R. Tschinkel of Florida State shows that for fire ants, at least, human disturbance of the environment is the main force behind their negative impact.

They demonstrated this by introducing fire ants into forest plots that were mowed and plowed. In The Proceedings of the National Academy of Sciences, they report that plowing by itself reduced the number and diversity of native ants greatly. Fire ants by themselves had less of an effect.

The researchers suggest that fire ants may not be so much an invasive species but a “disturbance specialist,” and that other species may fit that description, too.

By HENRY FOUNTAIN

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Scientists turning CO2 from coal-fired plants, algae into oil

By Jim Warren, General Science / Chemistry

They propose to employ algae to scrub carbon dioxide from the flue-gases of coal-fired power plants - of which Kentucky has many - and use the algae to produce an oil that could then be refined into fuel.

Carbon dioxide, or CO2, is the principal pollutant associated with global warming. But under UK's plan, algae would consume the power-plant CO2 as food, converting it into biomass from which algae oil could be removed and processed into biodiesel, jet fuel or similar products, researchers say.

Algae-based facilities to trap the CO2 would probably be located adjacent to coal-fired power plants in order to quickly receive and process their emissions.

"The reason algae is so interesting is that it can directly convert CO2 into biomass very quickly, more efficiently than anything else we know of," says Rodney Andrews, director of UK's Center for Applied Energy Research.

"Then, you basically squeeze the oil out of the algae and refine it as you would other natural oils."

The energy center is working on the project along with the UK College of Agriculture's Department of Biosystems and Agricultural Engineering. The state of Kentucky has provided more than $500,000 for the effort.

UK scientists say they hope to have a test facility operating within three to four years. If the algae-based system works, it could benefit both the electrical power industry and Kentucky's coal industry.

"The appeal is that if you have a power plant where you burn coal, and you capture the CO2 and use that to produce fuel with algae, you effectively become twice as efficient in the amount of energy achieved per ton of CO2 emitted," Andrews said.

As a first step in the research, Czarena Crofcheck, a biological engineer with the UK biosystems and agriculture engineering department, is searching for a strain of algae that would remove CO2 from power plant gases with the greatest efficiency.

In her search, Crofcheck watches over bubbling tanks called photo-bioreactors that contain various strains of algae in shifting shades of green. The darker the green, the more efficiently the algae in the tank is growing.

"These are my babies," she quips. "We're primarily interested in strains that grow quickly and consume CO2 very quickly."

Finding the right strain could take a while. Crofcheck notes that there are at least 50,000 species of algae.

And, as in many alternative energy projects, there are some problems to be overcome.

According to Andrews, capturing the carbon dioxide emitted from a 500-megawatt power plant would require 5,000 to 6,000 acres of ponds containing algae. To get around that, UK hopes to contain the algae in vessels that would operate more efficiently at much smaller size.

Expense is another issue. As of now, it costs $18 to $30 a gallon to produce algae oil, which then has to be refined into fuel.

But Andrews says producing fuel really is a secondary goal of the UK effort.

"The main idea is to get rid of the CO2 and then figure out what you do with the algae," he said.

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EU wants end to old-style bulbs

Light bulb above boxes of bulbs
Improvements to conventional bulbs reached a limit 50 years ago

A European Union report has recommended banning conventional incandescent light bulbs by 2012 to save energy and cut down on greenhouse gas emissions.

Most light bulbs sold in the EU are of the type pioneered by Thomas Edison in 1879.

But the report says the EU could save up to $12bn (£8bn) a year in energy bills by switching to low-energy bulbs.

The report needs the backing of the European parliament and all 27 member states to become law.

"It's very clear that this is a measure that will change the way that we consume energy," EU Energy Commissioner Andris Piebalgs told journalists.

Phase out

Once approved, the EU would phase out conventional bulbs between September 2009 and September 2012.


European homes will keep the same quality of lighting, while saving energy, CO2 and money
Andris Piebalgs
EU Energy Commissioner

Consumers will choose between long-life fluorescent bulbs or halogen lamps.

The EU says the measure will save households up to 50 euros ($64, £43) a year and pump up to 10bn euros ($13bn) into the economy.

The new-style lamps carry energy savings of 25% to 75% compared to traditional incandescent bulbs, which are little changed since they were invented almost 130 years ago.

The report also says the switch will reduce carbon dioxide emissions by 12 million metric tonnes (13.2 million tonnes) a year, and save energy equivalent to the consumption of 11 million European households.

Mr Piebalgs said that the phasing out had to be gradual so that "production facilities could adapt to the new lighting" and the quality of illumination could be ensured.

"European homes will keep the same quality of lighting, while saving energy, CO2 and money," he said.

Several nations including Australia, New Zealand, Canada and the Philippines have already announced they will phase out or restrict sales of traditional bulbs.

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2008 Will Be Just a Second Longer

By Andrea Thompson

Like the more well-known time adjustment, the leap year, a "leap second" is tacked on to clocks every so often to keep them correct.

Earth's trip around the sun — our year with all its seasons — is about 365.2422 days long, which we round to 365 to keep things simpler. But every four years, we add 0.2422 x 4 days (that's about one day) at the end of the month of February (extending it from 28 to 29 days) to fix the calendar.

Likewise, a "leap second" is added on to our clocks every so often to keep them in synch with the somewhat unpredictable nature of our planet's rotation, the roughly 24-hour whirl that brings the sun into the sky each morning.

Historically, time was based on the mean rotation of the Earth relative to celestial bodies and the second was defined from this frame of reference. But the invention of atomic clocks brought about a definition of a second that is independent of the Earth's rotation and based on a regular signal emitted by electrons changing energy state within an atom.

In 1970, an international agreement established two timescales: one based on the rotation of the Earth and one based on atomic time.

The problem is that the Earth is very gradually slowing down, continually throwing the two timescales out of synch, so every so often, a "leap second" has to be tacked on to the atomic clock.

The International Earth Rotation and Reference Systems Service is the organization that monitors the difference in the two timescales and calls for leap seconds to be inserted or removed when necessary. Since 1972, leap seconds have been added at intervals varying from six months to seven years — the most recent was inserted on Dec. 31, 2005.

In the United States, the U.S. Naval Observatory and the National Institute of Standards and Technology keep time for the country. The Naval Observatory keeps the Department of Defense's Master Clock, an atomic clock located in Washington, D.C.

The new extra second will be added on the last day of this year at 23 hours, 59 minutes and 59 seconds Coordinated Universal Time — 6:59:59 pm Eastern Standard Time.

Mechanisms such as the Internet-based Network Time Protocol and the satellite-based Global Positioning System (GPS) depend on the accurate time kept by atomic clocks.

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