Gas Rich Galaxies Confirm Prediction of Modified Gravity Theory

Recent data for gas rich galaxies precisely match predictions of a modified theory of gravity known as MOND, according to a new analysis by University of Maryland Astronomy Professor Stacy McGaugh. This -- the latest of several successful MOND predictions -- raises new questions about accuracy of the reigning cosmological model of the universe, writes McGaugh in a paper to be published in March in
Modern cosmology says that for the universe to behave as it does, the mass-energy of the universe must be dominated by dark matter and dark energy. However, direct evidence for the existence of these invisible components remains lacking. An alternate, though unpopular, possibility is that the current theory of gravity does not suffice to describe the dynamics of cosmic systems.

A few theories that would modify our understanding of gravity have been proposed. One of these is Modified Newtonian Dynamics (MOND), which was hypothesized in 1983 by Moti Milgrom a physicist at the Weizmann Institute of Science in Rehovot, Israel. One of MOND's predictions specifies the relative relationship between the mass of any galaxy and its flat rotation velocity. However, uncertainties in the estimates of masses of stars in star-dominated spiral galaxies (such as our own Milky Way) previously had precluded a definitive test.

To avoid this problem, McGaugh examined gas rich galaxies, which have relatively fewer stars and a preponderance of mass in the form of interstellar gas. "We understand the physics of the absorption and release of energy by atoms in the interstellar gas, such that counting photons is LIKE counting atoms. This gives us an accurate estimate of the mass of such galaxies," McGaugh said.

Using recently published work that he and other scientists had done to determine both the mass and flat rotation velocity of many gas rich galaxies, McGaugh compiled a sample of 47 of these and compared each galaxy's mass AND rotation velocity with the relationship expected by MOND. All 47 galaxies fell on or very close to the MOND prediction. No dark matter model performed as well.

"I find it remarkable that the prediction made by Milgrom over a quarter century ago performs so well in matching these findings for gas rich galaxies," McGaugh said. "

MOND vs. Dark Matter -- Dark Energy

Almost everyone agrees that on scales of large galaxy clusters and up, the Universe is well described by dark matter -- dark energy theory. However, according to McGaugh this cosmology does not account well for what happens at the scales of galaxies and smaller.

"MOND is just the opposite," he said. "It accounts well for the 'small' scale of individual galaxies, but MOND doesn't tell you much about the larger universe.

Of course, McGaugh said, one can start from the assumption of dark matter and adjust its models for smaller scales until it fits the current finding. "This is not as impressive as making a prediction ahead of [new findings], especially since we can't see dark matter. We can make any adjustment we need." This is rather like fitting planetary orbits with epicycles," he said. Epicycles were erroneously used by the ancient Greek scientist Ptolemy to explain observed planetary motions within the context of a theory for the universe that placed Earth in its center.

"If we're right about dark matter, why does MOND work at all?" asks McGaugh. "Ultimately, the correct theory -- be it dark matter or a modification of gravity -- needs to explain this."

Latest Pentagon Brainstorm: Nuke-Powered War Bases

Imagine the snow-capped peaks of mountainous eastern Afghanistan. Wouldn’t it be better topped off with a cooling tower for a nuclear reactor? The Pentagon’s way-out research arm thinks so. It’s all part of a big push to make the military more eco-friendly.

Buried within Darpa’s 2012 budget request under the innocuous name of “Small Rugged Reactor Technologies” is a $10 million proposal to fuel wartime Forward Operating Bases with nuclear power. It springs from an admirable impulse: to reduce the need for troops or contractors to truck down roads littered with bombs to get power onto the base. It’s time, Darpa figures, for a “self-sufficient” FOB.

Only one problem. “The only known technology that has potential to address the power needs of the envisioned self-sufficient FOB,” the pitch reads, “is a nuclear-fuel reactor.” Now, bases could mitigate their energy consumption, like the solar-powered Marine company in Helmand Province, but that’s not enough of a game-changer for Darpa. Being self-sufficient is the goal; and that requires going nuclear; and that requires … other things.

To fit on a FOB, which can be anywhere from Bagram Air Field’s eight square miles to dusty collections of wooden shacks and concertina wire, the reactor would have to be “well below the scale of the smallest reactors that are being developed for domestic energy production,” Darpa acknowledges.

That’s not impossible, says Christine Parthemore, an energy expert at the Center for a New American Security. The Japanese and the South Africans have been working on miniature nuclear power plants for the better part of a decade; Bill Gates has partnered with Toshiba to build mini-nuke sites. (Although it’s not the most auspicious sign that one prominent startup for modular reactors suspended its operations after growing cash-light last month.) Those small sites typically use uranium enriched to about 2 percent. “It would be really, really difficult to divert the fuel” for a bomb “unless you really knew what you were doing,” Parthemore says.

But Darpa doesn’t want to take that chance. Only “non-proliferable fuels (i.e., fuels other than enriched uranium or plutonium) and reactor designs that are fundamentally safe will be required of reactors that may be deployed to regions where hostile acts may compromise operations.”

Sensible, sure. But it limits your options: outside of uranium or plutonium, thorium is the only remaining source for generating nuclear fuel. The Indians and now the Chinese have experimented with thorium for their nuclear programs, but, alas, “no one has ever successfully found a way” to build a functioning thorium reactor, Parthemore says, “in a safe and economical manner.”

For now, Darpa proposes to spend $10 million of your money studying the feasibility of the project. But it’s just one part of the researchers’ new push to green the military. Another $10 million goes to a project called Energy Distribution, which explores bringing down energy consumption on the FOBs. An additional $5 million will look at ways to keep fuel storage from degrading in extreme temperatures. For $50 million, Darpa proposes to build a turbine engine that uses 20 percent less energy.

But all of that is mere isotopes compared to the Nuclear FOB. Darpa appears to have thought about it a lot. It says it plans to work with the Department of Energy “to ensure that existing advanced reactor development activities are being exploited and/or accelerated as appropriate, based on the military’s needs.”

Still, if it can’t find the right non-proliferable fuel, it suggests that it might look to the “development of novel fuels.” Says a stunned Parthemore, “I have no idea why you’d want to bring that upon the world.”

Photo: Nuclear Regulatory Commission

Herschel Measures Dark Matter for Star-Forming Galaxies

The Herschel Space Observatory has revealed how much dark matter it takes to form a new galaxy bursting with stars.
The findings are a key step in understanding how dark matter, an invisible substance permeating our universe, contributed to the birth of massive galaxies in the early universe.

"If you start with too little dark matter, then a developing galaxy would peter out," said astronomer Asantha Cooray of the University of California, Irvine. He is the principal investigator of new research appearing in the journal Nature, online on Feb. 16 and in the Feb. 24 print edition. "If you have too much, then gas doesn't cool efficiently to form one large galaxy, and you end up with lots of smaller galaxies. But if you have the just the right amount of dark matter, then a galaxy bursting with stars will pop out."

The right amount of dark matter turns out to be a mass equivalent to 300 billion of our suns.

Herschel launched into space in May 2009. The mission's large, 3.5-meter (11.5-foot) telescope detects longer-wavelength infrared light from a host of objects, ranging from asteroids and planets in our own solar system to faraway galaxies.

"This remarkable discovery shows that early galaxies go through periods of star formation much more vigorous than in our present-day Milky Way," said William Danchi, Herschel program scientist at NASA Headquarters in Washington. "It showcases the importance of infrared astronomy, enabling us to peer behind veils of interstellar dust to see stars in their infancy."

Cooray and colleagues used the telescope to measure infrared light from massive, star-forming galaxies located 10 to 11 billion light-years away. Astronomers think these and other galaxies formed inside clumps of dark matter, similar to chicks incubating in eggs.

Giant clumps of dark matter act like gravitational wells that collect the gas and dust needed for making galaxies. When a mixture of gas and dust falls into a well, it condenses and cools, allowing new stars to form. Eventually enough stars form, and a galaxy is born.

Herschel was able to uncover more about how this galaxy-making process works by mapping the infrared light from collections of very distant, massive star-forming galaxies. This pattern of light, called the cosmic infrared background, is like a web that spreads across the sky. Because Herschel can survey large areas quickly with high resolution, it was able to create the first detailed maps of the cosmic infrared background.

"It turns out that it's much more effective to look at these patterns rather than the individual galaxies," said Jamie Bock of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Bock is the U.S. principal investigator for Herschel's Spectral and Photometric Imaging Receiver instrument used to make the maps. "This is like looking at a picture in a magazine from a reading distance. You don't notice the individual dots, but you see the big picture. Herschel gives us the big picture of these distant galaxies, showing the influence of dark matter."

The maps showed the galaxies are more clustered into groups than previously believed. The amount of galaxy clustering depends on the amount of dark matter. After a series of complicated numerical simulations, the astronomers were able to determine exactly how much dark matter is needed to form a single star-forming galaxy.

"This measurement is important, because we are homing in on the very basic ingredients in galaxy formation," said Alexandre Amblard of UC Irvine, first author of the Nature paper. "In this case, the ingredient, dark matter, happens to be an exotic substance that we still have much to learn about."

Herschel is a European Space Agency cornerstone mission supported with important NASA contributions. NASA's Herschel Project Office is based at JPL, which contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the U.S. astronomical community. JPL is managed by Caltech.

More information is online at http://www.herschel.caltech.edu, http://www.nasa.gov/herschel and http://www.esa.int/SPECIALS/Herschel/index.html .

Ozone Layer’s Future Linked Strongly to Changes in Climate, Study Finds

The ozone layer -- the thin atmospheric band high-up in the stratosphere that protects living things on Earth from the sun's harmful ultraviolet rays, not to be confused with damaging ozone pollution close to the ground -- faces potential new challenges even as it continues its recovery from earlier damage, according to a recently released international science assessment. The report, prepared by the Scientific Assessment Panel of the U.N. Montreal Protocol on Substances that Deplete the Ozone Layer, also presents stronger evidence that links changes in stratospheric ozone and Earth's climate.

The report finds that over the past decade, global ozone levels, and ozone levels in the Arctic and Antarctic regions are at a turnaround point -- no longer decreasing but not yet increasing. The abundances of ozone-depleting substances in the atmosphere are responding as expected to the controls of the Montreal Protocol, with many now declining in both the lower and upper atmosphere.

By successfully controlling the emissions of ozone-depleting substances, the Montreal Protocol also has been beneficial for the climate, because many of these substances are heat trapping, or greenhouse, gases that are linked to Earth's warming.

"The Montreal Protocol has succeeded in protecting the ozone layer from much higher levels of depletion," said A.R. Ravishankara, director of NOAA's Chemical Sciences Division and co-chair of the Scientific Assessment Panel that produced the report. "But the ozone layer will increasingly be influenced by other factors related to the changing climate."

For example, climate change alters the atmosphere's temperature and circulation patterns, which in turn affect the processes that deplete the ozone layer. One projected outcome of this relationship is that ozone in the Arctic, where the most severe changes in climate are being observed, is projected to be more sensitive to climate changes than ozone in the Antarctic, where climate change is relatively less of an influence on the ozone layer.

Effects also work in reverse. Changes in the ozone layer have been linked to observed shifts in seasonal surface winds over the Southern Hemisphere, contributing to the Antarctic Peninsula warming and the high plateau cooling.

The Antarctic ozone hole was discovered in 1985. Soon after, scientists established that the recurring springtime ozone hole was caused by human-made substances such as chlorofluorocarbons, or CFCs, used in refrigeration and halons used in fire extinguishers. The findings became a "science success story" as governments recognized the need for measures to reduce the production and consumption of a number of CFCs, halons and other ozone-depleting substances.

The Montreal Protocol on Substances that Deplete the Ozone Layer was adopted in 1987 and came into force in 1989. It was designed so that the schedules for phasing out ozone-depleting substances could be revised based on periodic scientific and technological assessments, be amended or adjusted to introduce other kinds of control measures, and to add new controlled substances to the list. The 2010 scientific assessment just released provides information needed by the Protocol's decision-makers during the coming few years as they consider possible further actions to protect the ozone layer.

A return to pre-1980 levels of ozone is expected around mid-century in mid-latitude regions and the Arctic, with recovery in the Antarctic expected to follow later this century, according to the assessment.

The ozone layer's continued protection depends on future adherence to the provisions of the Montreal Protocol, as well as potential new influences, such as possible unintended consequences of proposals to deliberately add compounds to the atmosphere to counteract warming due to heat-trapping gases.

"The Montreal Protocol is doing what it was designed to do and we are seeing less of the ozone-depleting substances covered by the agreement," said Ravishankara. "This has protected the ozone layer. But the atmosphere and climate are changing, so the ozone layer will not exactly retrace its steps."

NOAA scientists and colleagues contributed findings that were critical to the assessment report. Namely, they led studies that determined the cause of the Antarctic ozone hole and elucidated the processes involved in ozone depletion in other regions of the globe. Teams have also tracked the state of the ozone layer and the abundances of ozone-depleting substances in the atmosphere, and modeled the past and projected future state of the ozone layer.

The 2010 assessment was conducted under the auspices of the United Nations Environment Programme and the World Meteorological Organization. It involved more than 300 international scientists as authors and reviewers.

The full report is posted on the UNEP website: http://www.unep.ch/ozone/Assessment_Panels/SAP/index.shtml

Underground Cave Dating From The Year 1 A.D. Exposed In Jordan Valley

An artificial underground cave, the largest in Israel, has been exposed in the Jordan Valley in the course of a survey carried out by the University of Haifa's Department of Archaeology. Prof. Adam Zertal, who headed the excavating team, reckons that this cave was originally a large quarry during the Roman and Byzantine era and was a "one of a kind." Various engravings were uncovered in the cave, including cross markings, and it is assumed that this could have been an early monastery.
"It is probably the site of "Galgala" from the historical Madaba Map," Prof. Zertal says.

The enormous and striking cave covers an area of approximately 1 acre: it is some 100 meters long and about 40 meters wide. The cave is located 4 km north of Jericho. The cave, which is the largest excavated by man to be discovered in Israel, was exposed in the course of an archaeological survey that the University of Haifa has been carrying out since 1978.

As with other discoveries in the past, this exposure is shrouded in mystery. "When we arrived at the opening of the cave, two Bedouins approached and told us not to go in as the cave is bewitched and inhabited by wolves and hyenas," Prof. Zertal relates. Upon entering, accompanied by his colleagues, he was surprised to find an impressive architectonic underground structure supported by 22 giant pillars. They discovered 31 cross markings on the pillars, an engraving resembling the zodiac symbol, Roman letters and an etching that looks like the Roman Legion's pennant. The team also discovered recesses in the pillars, which would have been used for oil lamps, and holes to which animals that were hauling quarried stones out of the cave could have been tied.

The cave's ceiling is some 3 meters high, but was originally probably about 4 meters high. According to Prof. Zertal, ceramics that were found and the engravings on the pillars date the cave to around 1-600 AD. "The cave's primary use had been as a quarry, which functioned for about 400-500 years. But other findings definitely indicate that the place was also used for other purposes, such as a monastery and possibly as a hiding place," Prof. Zertal explains.

The main question that arose upon discovering the cave was why a quarry was dug underground in the first place. "All of the quarries that we know are above ground. Digging down under the surface requires extreme efforts in hauling the heavy rocks up to the surface, and in this case the quarrying was immense. The question is, why?"

For a possible answer to this mystery, Prof. Zertal points to the famous Madaba map. This is a Byzantine mosaic map that was found in Jordan and is the most ancient map of the Land of Israel. Jerusalem and the Jordan Valley are depicted with precision on the map, and a site called Galgala is depicted next to a Greek inscription that reads "Dodekaliton", which translates as "Twelve Stones." This place is marked at a distance from Jericho that matches this cave's distance from the city.

According to the map, there is a church next to Dodekaliton; there are two ancient churches located nearby the newly discovered cave. According to Prof. Zertal, until now it has been hypothesized that the meaning of "Twelve Stones" related to the biblical verses that describe the twelve stones that the Children of Israel place in Gilgal. However, it could be that the reference is a description of the quarry that was dug where the Byzantines identified the Gilgal.

"During the Roman era, it was customary to construct temples of stones that were brought from holy places, and which were therefore also more valuable stones. If our assumption is correct, then the Byzantine identification of the place as the biblical Gilgal afforded the site its necessary reverence and that is also why they would have dug an underground quarry there," Prof. Zertal concludes. "But" he adds, "much more research is needed."

First Skyscraper Was a Monument to Intimidation: How Jericho's 11,000-Year-Old 'Cosmic' Tower Came Into Being

Discovered by archaeologists in 1952, a 28-foot-high stone tower discovered on the edge of the town of Jericho has puzzled scientists ever since. Now, eleven millennia after it was built, Tel Aviv University archaeologists at the ancient site Tel Jericho are revealing new facts about the "world's first skyscraper."

Recent computer-based research by doctoral student Roy Liran and Dr. Ran Barkai of Tel Aviv University's Jacob M. Alkow Department of Archaeology and Ancient Near Eastern Cultures at the Lester and Sally Entin Faculty of Humanities sheds light on who built the 28-foot-high tower -- and why.

The researchers note that this is the first instance of human beings erecting such a tall structure, even before the transition to agriculture and food production in the region. Liran and Dr. Barkai now believe that the tower, which required about ten years to build, is an indication of power struggles at the beginning of the Neolithic period, and that a particular person or people exploited the primeval fears of Jericho's residents in persuading them to build it. The new revelations about the ancient tower were recently published in the journal Antiquity.

"In the newly published article, we present a new and exciting discovery," Liran and Dr. Barkai said in a joint statement, "which is connected to the exact position of the tower on the edges of the village of Jericho, and the shadow that covers the site when the sun sets on the longest day of the year."

A stairway (and tower) to Heaven

"Reconstruction of the sunset revealed to us that the shadow of the hill as the sun sets on the longest day of the year falls exactly on the Jericho tower, envelops the tower and then covers the entire village," the researchers explained. "For this reason, we suggest that the tower served as an earthly element connecting the residents of the site with the hills around them and with the heavenly element of the setting sun." Its construction may be related to the primeval fears and cosmological beliefs of the villagers, they note.

Tel Jericho, located in modern day Jericho in the West Bank, is one of the most ancient sites in the world. The eight and half meter tower, which was built with a steep flight of stairs approximately one meter wide, rises above a four-meter wall that probably encompassed the city. The existence of the tower led to Jericho's identification as the first city in the world, even though it was in fact a settlement of pre-agricultural hunter gatherers.

"This was a time when hierarchy began and leadership was established," Dr. Barkai told the Jerusalem Post. "We believe this tower was one of the mechanisms to motivate people to take part in a communal lifestyle."

Debunking old theories

Some researchers have proposed that the tower and wall together comprised a system of fortification and a defense against flooding. Others have suggested the tower and wall as a geographical marker, defining the territory of the early residents of Jericho, and a symbol of the wealth and power of the ancient village.

In a 2008 article, the Tel Aviv University researchers proposed that the tower and wall of Jericho should be seen as cosmological markers, connecting the ancient village of Jericho with the nearby Mount Qarantal and sunset on the longest day of the year. The new paper fortifies their hypothesis.

This idea is based on the fact that the axis of the flight of stairs in the tower was built at a precise angle to the setting of the sun on the longest day of the year behind the highest peak overlooking Jericho, Mount Qarantal. They believe that it is humanity's first skyscraper, however small, and also the world's first public building.

Lystrosaurs

An artist's depiction shows lystrosaurs foraging near a stream. Flat-faced with a beak and two teeth that resembled tusks, lystrosaurs were synapsids, animals that arose in the Permian and eventually gave rise to mammals.