Solar System’s Rocky Beginning Confirmed

Rocks melted in the early solar system after electrical currents spiked through the cloud of dust circling around the young sun, according to new research.

The finding brings scientists a step closer to understanding the origin of the chondrules, or glass beads, that were some of the solar system’s first solids.

Because chondrules form far away from the sun, astronomers could not figure out how they heated to at least 2,420 degrees Fahrenheit (1,600 degrees Kelvin), since the surrounding environment is much colder, according to observations.

More mysteriously, the rocks apparently cooled within an hour or two after forming, instead of freezing instantly into a crystal, which would be expected in space.

“This was a puzzle, because quite a lot of material must have passed through this process,” said Mordecai-Mark Mac Low, the chair of astrophysical sciences at the American Museum of Natural History in New York. [Planetfall: Wonders of the Solar System (Photos)]

A typical early meteorite, called a chondrite, could be made up of 70 to 80 percent of this glassy material. “It’s a large fraction of mass, even in regions far away from the sun where the sun can’t [heat] it,” said Mac Low, who is also an adjunct professor at Columbia University.

Mac Low co-authored a paper reporting the findings that was published in the March 20 edition of The Astrophysical Journal Letters.

Bound by magnetism

Chondrules are one of two types of solids that made up the early solar system. Chondrules are clumps of dust that heated up and cooled rapidly, while the second type of solid — calcium-aluminum rich inclusions (CAIs) — was created from molten gas droplets.

A separate study, based on dating techniques, recently proposed that chondrules and CAIs formed at the same timein Earth’s solar system, just a few million years after the protoplanetary disc of spinning matter formed around the nascent sun.

This spinning disc of matter, Mac Low said, contained an enormous amount of kinetic energy. This was the biggest source of energy for disc motions. Differential rotation, and energy, increased the amount of kinetic energy in the disc as regions closer to the sun rotated faster than regions farther out.

Material was dragged on to the young sun through a process called magnetorotational instability. This occurs when a weak magnetic field runs through differentially rotating gas, connecting regions orbiting at different speeds. The turbulence mixed angular momentum outward, allowing the bulk of the gas to fall inward and accrete onto the sun.

“That appears to be one of the major mechanisms to drive accretion,” Mac Low said, adding that it could even be applicable to black holes.

In the solar system, however, Mac Low’s research team suspects magnetorotational instability may also fuel the formation of chondrules.

Fluorescent light bulb question

Magnetized turbulence bends magnetic fields, producing electrical currents. These currents travel through the resistive gas, heating it. This is the same process that allows heating to happen in toasters and electric ovens.

The bent magnetic fields in the disc form thin, flat regions of strong electrical current called “current sheets.” The production of current sheets by magnetized turbulence has been known by plasma researchers since the 1970s, but Mac Low’s team applied this understanding of current sheet formation to protoplanetary discs for the first time.

The question was, Mac Low said, how much the sheets heated the rocks.

“We might just get a fluorescent light bulb,” he joked, adding that it seemed quite possible given most of the protoplanetary disc was made of neutral gas. At first glance, there were not a lot of ions, or charged particles, to carry the current.

Museum researcher Alexander Hubbard, co-author of the study, then came upon the answer. A little heating will start to excite the atoms that are easiest to ionize — namely, salty substances such as potassium and sodium.

Warming those substances will ionize them, which will increase the available current. With more ions in the current, the substances would heat even more and increase ionization exponentially.

“It looks like something that could get us up to the temperature we needed,” Mac Low said.

Aiming for three dimensions

Next, the researchers tried to figure out why the chondrules cooled slowly in the cold reaches of space. Dust opacity, or thickness, changes with the temperature. As the dust melted, the highest temperature region formed a transparent cavity, surrounded by opaque material still warmed by radiation from the hottest gas.

“The newsworthy conclusion is that under conditions reasonable for protoplanetary discs, these regions can get plenty hot. Sometimes over 2,000 Kelvin (3,140 Fahrenheit), hot enough to melt rocks,” Mac Low said.

So far, the researchers have simulated this process in only one dimension. The next step will be to move toward a three-dimensional model to better simulate conditions in the early solar system.

While the paper did not include new observations, Mac Low pointed out that Chile’s Atacama Large Millimeter/submillimeter Array (ALMA) could, in time, partially confirm the findings.

“We won’t be able to observe individual current sheets … but ALMA will be able to tell us about dust grain size and distribution,” he said of the telescope, which was officially inaugurated this month.

The research was led by Denmark’s Niels Bohr International Academy and includes scientists from the American Museum of Natural History, Columbia University and the National Autonomous University of Mexico.

Courtesy-Space

 

Can CFCs Help Find Alien Life?

Hairspray might one day serve as the sign that aliens have reshaped distant worlds, researchers say. Such research to find signs of alien technology is now open to funding from the public.

Science fiction has long imagined that humans could transform hostile alien worlds into livable ones, a procedure known as terraforming. For instance, to colonize Mars, scientists have suggested warming the red planet and thickening its extraordinarily thin atmosphere so that humans can roam its surface without having to wear spacesuits. To do so, plans to terraform Mars often involve vast amounts of greenhouses gases to trap enough heat from the Sun, forcing carbon dioxide frozen on the planet’s surface to turn into gas.

If humans might one day terraform planets, aliens with more advanced technology might have already done so. If that’s the case, astronomers could look for telltale signs of such changes to reveal that intelligent extraterrestrial life exists. [The Search for Extraterrestrial Life (Video Show)]

that evidence of intelligent life might be evident in a planetary atmosphere,” said astrobiologist Mark Claire at the Blue Marble Space Institute of Science, a nonprofit network of scientists across the world.

One group of gases that might be key to terraforming planets are chlorofluorocarbons (CFCs). These nontoxic, long-lived chemicals are strong greenhouse gases and were once often used in hairspray and air conditioners, among many other products.

CFCs are entirely artificial, with no known natural process capable of creating them in atmospheres. Detecting signs of these gases on far-off worlds with telescopes might serve as potent evidence that intelligent alien civilizations were the cause, either intentionally as part of terraforming or accidentally via industrial pollution.

“An industrialized civilization will be one that will use its planetary resources for fabrication, the soon-to-be-detectable-from-Earth atmospheric byproducts of which could be a tell-tale sign of their activity,” said astrobiologist Sanjoy Som of the Blue Marble Space Institute of Science.

Telescopes have currently helped spot hundreds of exoplanets so far and should help detect hundreds more soon. Future observatories could analyze the atmospheres of these worlds, and CFCs should be easy to see, because the way they absorb light is very different from naturally-occurring chemicals.

“We are on the scientific verge of being able to actively look for extrasolar worlds inhabited by technological civilizations,” Som said. “We are about a decade away of being able to measure detailed compositions of the atmospheres of extrasolar planets.”

Using state-of-the-art computer models of atmospheric chemistry and climate, the researchers plan to discover what visible signs CFCs and other artificial byproducts of alien terraforming or industry might have on exoplanet atmospheres.

“We will then test if these features are detectable over interstellar distances, by severely downgrading our computed signal to mimic the signal quality of next-generation telescopes,” Claire said.

Scientists worldwide could then use this data to see if any of the exoplanets discovered so far or to come show evidence of these “technosignatures.”

“This SETI proposal is about looking at atmospheric chemistry rather than other previously proposed technosignatures like radio signals or pulsed light beams,” Claire said.

Claire added that sulfur hexaflouride is another industrial molecule and greenhouse gas that could serve as a technosignature. Other technosignatures may include unusually large amounts of ammonia or carbon dioxide, when observed alongside gases such as oxygen and water vapor, which are often thought to be common signs of life, Som said.

The researchers are now seeking startup money for their project from the public via the Petridish organization. They hope to raise $24,000 by January 9, 2013.

“This project will move forward only if it is funded. We invite the public to take part and be included in our adventures by pledging a small amount of money to our efforts,” Som said. “We are a small 501(c)3 non-profit science organization with a strong emphasis in science communication. All donations are tax-deductible!”

This research could also help astrobiologists discover signs of alien intelligence outside the so-called habitable zones where hunts for extraterrestrial life is often most focused on. There is life virtually wherever there is liquid water on Earth, so habitable zones are often thought of as the areas around stars where liquid water can persist on a planet’s surface, given temperatures that are neither too hot nor too cold.

“Artificially warming a body outside of the habitable zone to make it habitable could also be a tell-tale sign of intelligence,” Som said. “For example, suppose that in a few thousand years, humans have terraformed Mars. Suppose that an alien species is observing our solar system and finds Earth. In addition, it measures the atmospheric composition of Mars, a planet essentially outside the habitable zone of our sun, and finds elevated greenhouses gasses in addition to water vapor and oxygen. This two-planet system would be a strong indication to them of an intelligent civilization at work expanding its cradle outside of its home planet.”

This may be the first scientific investigation of what a terraformed planet might look like from afar, and could be a new tool in the search for extraterrestrial intelligence (SETI). It goes without saying that if these efforts help discover intelligent alien life, “the implications will be tremendous, as it will cause a major reassessment of what it means to be human,” Som said.

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Is Pluto’s Atmosphere Bigger Than Previous Estimates?

A new simulation of Pluto’s upper atmosphere shows that it extends so far from the planet that stray molecules may be deposited on its largest moon, Charon.

The new model predicts that Pluto’s atmosphere can extend as far as 6,456 miles (10,390 kilometers) into space, or about 4.5 times the diameter of Pluto. That’s more than halfway to Charon.

“That is amazing, from my perspective,” said Justin Erwin, the lead author of the paper and a Ph.D. student at the University of Virginia.

Researchers combined two previously known models of Pluto‘s atmosphere to better estimate the escape rate of molecules into space. Their refinement made a big difference.

“Our [calculated escape rate] is a little bit smaller, but the small change in the escape rate causes a large change in the structure of the atmosphere,” Erwin added.

Erwin’s supervisor at the University of Virginia, Robert Johnson, was a co-author of the paper reporting the findings, which was published on the preprint site Arxiv and has been submitted to the journal Icarus for publication.

Fire and ice

Pluto’s tenuous atmosphere is mainly composed of methane, nitrogen and poisonous carbon monoxide that likely comes from ice on the dwarf planet’s surface. The size of the atmosphere changes as Pluto moves closer and farther from the sun in its elliptical orbit.

When Pluto swings near the sun, the sun’s heat evaporates the ice and gases slowly escape into space. This process continues until Pluto moves away and the sun’s heat fades. Then, the ice builds up until Pluto approaches the sun again.

Pluto’s last close approach to the sun was in 1989. That is considered a fairly recent event, because it takes 248 years for the dwarf planet to orbit the sun once.

Researchers are trying to refine the escape rate of the gases ahead of the arrival of NASA’s New Horizons probe at Pluto in 2015, so that the spacecraft knows what to look for. For the new calculations, Erwin’s team used previously published research from themselves and other scientists. [Destination Pluto: NASA's New Horizons Mission in Pictures]

Uncertain atmospheric model

It’s difficult to figure out the size of Pluto’s atmosphere because of a debate over how best to measure it.

Pluto’s atmosphere is heated by infrared and ultraviolet light from the sun. Closer to the planet, ultraviolet light is absorbed in the atmosphere and only infrared heating takes place.

But farther away from the planet, the atmosphere is thin enough that the ultraviolet light affects the molecules. This is why researchers use ultraviolet heating models for the upper reaches of the atmosphere.

Molecules that are escaping from Pluto’s atmosphere move through a region called the thermosphere. The thermosphere is where much of the ultraviolet light is absorbed in the atmosphere; this heating drives the escape process.

In the exosphere, at the top of Pluto’s atmosphere, the atmosphere is so tenuous that collisions between particles do not happen as frequently.

The boundary between the thermosphere and the exosphere is called the exobase. Researchers aren’t sure where the “boundary” is. Because the mathematical model for each section of the atmosphere is different, this leads to vast uncertainties in calculating the size of Pluto’s atmosphere.

Last year, Erwin participated in an Icarus paper that demonstrated a new model to estimate the upper atmosphere’s extent during the solar minimum (when Pluto receives the least heat from the sun).

This time around, Erwin and his co-authors extended that model to include solar maximum — when Pluto is warmest — and solar medium, or average heating.

Pluto is so far from Earth, and so small, that its size isn’t precisely known. When forming their model, the researchers assumed that the diameter of Pluto is roughly 1,429 miles (2,300 kilometers). However, the accepted range for the diameter differs by as much as 62 miles (100 km).

The New Horizons team plans to better measure the size of Pluto and its atmosphere when the spacecraft swings by Pluto in 2015.

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New Procedure Being Used To Probe Hot Jupiter Planets

The atmospheres of alien planets can now be probed even if they are not illuminated by stars directly behind them, astronomers say.

A new method used to scan the atmosphere of a distant “hot Jupiter” world could eventually reveal insights about many distant alien planets — including, perhaps, whether or not they support life, the researchers added.

“If we could detect gases like oxygen, these could point to biological activity,” study co-author Ignas Snellen, an astronomer at Leiden University in the Netherlands, told SPACE.com.

A new look at exoplanet atmospheres

Scientists have analyzed the atmospheres of exoplanets before, but only when those worlds passed in front of their parent stars, much like Venus did during its recent transit of the sun.

The change in the light of a star as it streams through an exoplanet’s atmosphere can reveal details about the air’s composition. Different molecules absorb light in distinct ways, resulting in patterns known as spectra that allow scientists to identify what they are. [Gallery: The Strangest Alien Planets]

Now scientists have for the first time analyzed the atmosphere of an exoplanet that, like most such alien worlds, does not pass between its star and Earth.

The planet in question is Tau Boötis b, one of the first exoplanets to be discovered back in 1996 and one of the nearest exoplanets to Earth known, at about 51 light-years away. The world is a “hot Jupiter” — a gas giant orbiting very close to its parent star.

The exoplanet’s parent star, Tau Boötis, is easily visible with the naked eye, but the planet is not. Up to now, Tau Boötis b was only detectable through its gravitational pull on the star.

An international team caught the faint infrared glow from Tau Boötis b using the European Southern Observatory‘s Very Large Telescope (VLT).

“We were able to study the spectrum of the system in much more detail than has been possible before,” study lead author Matteo Brogi, of Leiden Observatory in the Netherlands, said in a statement. “Only about 0.01 percent of the light we see comes from the planet, and the rest from the star, so this was not easy.”

A wealth of information

Seeing the planet’s light directly also enabled the astronomers to measure the angle of the planet’s orbit, helping them deduce its mass — six times that of Jupiter’s — accurately for the first time.

“The new VLT observations solve the 15-year-old problem of the mass of Tau Boötis b. And the new technique also means that we can now study the atmospheres of exoplanets that don’t transit their stars, as well as measuring their masses accurately, which was impossible before,” Snellen said. “This is a big step forward.”

The spectra also yielded details about the temperature of the exoplanet’s atmosphere at different altitudes. Surprisingly, they found the planet’s atmosphere seems to be cooler higher up, the opposite of what is seen with other hot Jupiters.

Earth’s atmosphere is cooler at higher altitudes, the closer air gets to the frigid depths of space. Hot Jupiters, on the other hand, typically have atmospheres that are warmer farther up, perhaps due to gases present in their higher layers, such as titanium oxide.

Tau Boötis is a star very high in ultraviolet activity, radiation that may destroy these heat-absorbing gases and give Tau Boötis b an atmosphere with temperature features more like Earth’s, researchers said.

The researchers focused on the spectrum of carbon monoxide, which is expected to be the second-most common gas in the atmospheres of hot Jupiters, after hydrogen. Unlike hydrogen, carbon monoxide has very strong and observable infrared spectral features. Future research can concentrate on other common gases in hot Jupiter atmospheres, such as water vapor and methane.

“Our method shows that exoplanet atmospheres can be very well studied using ground-based telescopes,” Snellen said. Although Tau Boötis b is much too hot for any life, “possibly in the future we can extend this method to study much cooler planets like the Earth.”

The scientists detailed their findings in the June 28 issue of the journal Nature.

 

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Voyager 1 About To Kiss The Solar System Goodbye

NASA’s Voyager 1 spacecraft has encountered a new environment more than 11 billion miles from Earth, suggesting that the venerable probe is on the cusp of leaving the solar system.

The Voyager 1 probe has entered a region of space with a markedly higher flow of charged particles from beyond our solar system, researchers said. Mission scientists suspect this increased flow indicates that the spacecraft — currently 11.1 billion miles (17.8 billion kilometers) from its home planet — may be poised to cross the boundary into interstellar space.

“The laws of physics say that someday Voyager will become the first human-made object to enter interstellar space, but we still do not know exactly when that someday will be,” said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena, in a statement.

“The latest data indicate that we are clearly in a new region where things are changing more quickly,” Stone added. “It is very exciting. We are approaching the solar system’s frontier.” [Photos From NASA's Voyager 1 and 2 Probes]

Far-flung spacecraft

Voyager 1 and its twin, Voyager 2, launched in 1977, tasked chiefly with studying Saturn, Jupiter and the gas giants’ moons. The two spacecraft made many interesting discoveries about these far-flung bodies, and then they just kept going, checking out Uranus and Neptune on their way toward interstellar space.

They’re not quite out of the solar system yet, however. Both are still within a huge bubble called the heliosphere, which is made of solar plasma and solar magnetic fields. This gigantic structure is about three times wider than the orbit of Pluto, researchers have said.

Specifically, the Voyagers are plying the heliosphere’s outer shell, a turbulent region called the heliosheath. But Voyager 1′s new measurements — of fast-moving galactic cosmic rays hurled our way by star explosions — suggest the probe may be nearing the heliosphere’s edge.

“From January 2009 to January 2012, there had been a gradual increase of about 25 percent in the amount of galactic cosmic rays Voyager was encountering,” Stone said. “More recently, we have seen very rapid escalation in that part of the energy spectrum. Beginning on May 7, the cosmic ray hits have increased five percent in a week and nine percent in a month.”

More measurements needed

While it may be tough to identify the moment when Voyager 1 finally pops free into interstellar space, scientists are keeping an eye on the cosmic ray measurements and a few other possible indicators.

One is the intensity of energetic particles generated inside the heliosphere. Voyager 1 has recorded a gradual decline in these particles as it flies farther and farther away from Earth, but it hasn’t seen the dramatic dropoff that scientists expect would accompany an exit from the solar system.

The Voyager team also thinks the magnetic fields surrounding the spacecraft should change when it crosses the solar boundary. Those field lines run roughly east-west within the heliosphere, and researchers predict they’ll shift to a more north-south orientation in interstellar space. They’re currently looking at Voyager 1 data for any signs of such a transition.

In the meantime, both Voyagers just keep on flying and exploring. Voyager 2 trails its twin a little bit; it’s currently 9.1 billion miles (14.7 billion km) from home.

“When the Voyagers launched in 1977, the space age was all of 20 years old,” Stone said. “Many of us on the team dreamed of reaching interstellar space, but we really had no way of knowing how long a journey it would be — or if these two vehicles that we invested so much time and energy in would operate long enough to reach it.”

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The Universe Appears To Be Expanding Quickly

The pesky reality that the universe’s expansion is accelerating — an observation that prompted astronomers to invoke an unknown entity called dark energy to explain it — has been further confirmed by new measurements.

Scientists have used cosmic magnifying glasses called gravitational lenses to observe super-bright distant galaxies, giving a measure of how quickly the universe is blowing up like a giant balloon. They found, in agreement with previous measurements, that the universe’s expansion is indeed speeding up over time.

The first measurement of this phenomenon, based on exploding stars called supernovae, was made in the 1990s.

“The accelerated cosmic expansion is one of the central problems in modern cosmology,” Masamune Oguri, of the University of Tokyo’s Kavli Institute for the Physics and Mathematics of the Universe, said in a statement. “In 2011 the Nobel Prize in Physics was awarded to the discovery of the accelerated expansion of the universe using observations of distant supernovae. A caution is that this method using supernovae is built on several assumptions, and therefore independent checks of the result are important in order to draw any robust conclusion.”

Scientists still don’t have much of an idea why the universe is not only expanding doing so ever-faster. The gravity of all the mass in the universe would be expected to pull everything back inward, so scientists call whatever force is counteracting gravity “dark energy.”

“Our new result using gravitational lensing not only provides additional strong evidence for the accelerated cosmic expansion, but also is useful for accurate measurements of the expansion speed, which is essential for investigating the nature of dark energy,” Oguri said.

Ogiri led the new study of quasars with Naohisa Inada at Japan’s Nara National College of Technology.

Quasars are objects bright enough to be spotted halfway across the universe. They are thought to be powered by hungry black holes that gobble up copious amounts of matter in the centers of galaxies, releasing radiant jets of light that shoot out into space.

The light from quasars sometimes passes by massive objects on its way to telescopes on Earth, and the gravity from these objects bends space-time, causing the light to travel along a curved path. This can produce warped and distorted double images of a single distant quasar. [Video: Quasar Details Seen With Gravitational Lenses]

As the universe expands, the distance to quasars increases, and so do the chances that a quasar’s light will pass by a massive object and be gravitationally lensed.

Thus the frequency of gravitationally lensed quasars can indicate the expansion speed of the universe.

Ogiri, Inada and their colleagues searched for such quasars in the catalog of the Sloan Digital Sky Survey (SDSS), which took detailed observations of giant swaths of the night sky. In a collection of about 100,000 quasars, the researchers identified 50 that were being gravitationally lensed, significantly increasing the known total sample of these objects.

The researchers used their calculation of the frequency of gravitationally lensed quasars to deduce that the universe’s expansion is indeed accelerating.

The new results will be reported in an upcoming paper published in the Astronomical Journal.

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Courtesy-Space.com

 

Hackers Hit NASA 13 Times Last Year

NASA said hackers stole employee credentials and used the information to gain access to mission-critical projects last year in 13 major network intrusions that could compromise U.S. national security.

National Aeronautics and Space Administration Inspector General Paul Martin testified before Congress this week on the breaches, which appear to be among the more significant in a string of security problems for federal agencies.

The space agency discovered in November that hackers working through an Internet Protocol address in China broke into the -network of NASA’s Jet Propulsion Laboratory, Martin said in testimony released on Wednesday. One of NASA’s key labs, JPL manages 23 spacecraft conducting active space missions, including missions to Jupiter, Mars and Saturn.

He said the hackers gained full system access, which allowed them to modify, copy, or delete sensitive files, create new user accounts and upload hacking tools to steal user credentials and compromise other NASA systems. They were also able to modify system logs to conceal their actions.

“Our review disclosed that the intruders had compromised the accounts of the most privileged JPL users, giving the intruders access to most of JPL’s networks,” he said.

In another attack last year, intruders stole credentials for accessing NASA systems from more than 150 employees. Martin said the his office identified thousands of computer security lapses at the agency in 2010 and 2011.

He also said NASA has moved too slowly to encrypt or scramble the data on its laptop computers to protect information from falling into the wrong hands.

Unencrypted notebook computers that have been lost or stolen include ones containing codes for controlling the International Space Station, as well as sensitive data on NASA’s Constellation and Orion programs, Martin said.

A NASA spokesman told Reuters on Friday the agency was implementing recommendations made by the Inspector General’s Office.

“NASA takes the issue of IT security very seriously, and at no point in time have operations of the International Space Station been in jeopardy due to a data breach,” said NASA spokesman Michael Cabbagehe.

 

The Universe Apparently Expanded By Inflation

The distribution of matter across the cosmos is most easily explained by inflation, a theory that suggests our universe inflated rapidly — just like a balloon — shortly after its birth, according to new research.

A new study found that cosmic inflation, which was first proposed in 1980, is the simplest explanation that fits the measurements of the distribution of matter throughout the universe made by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), a spacecraft that scans radiation left over from the Big Bang.

According to inflation, the universe expanded by a factor of at least 10⁷⁸ (that’s 10 with 78 zeroes after it), all in less than a second. This stage could have formed the basis for the large-scale structure we can detect in the distribution of galaxies around us now.

This theory can explain why the universe appears to be about 13.7 billion years old, and why it seems to be nearly flat, say University at Buffalo physicists Ghazal Geshnizjani, Will Kinney and Azadeh Moradinezhad Dizgah. The researchers recently analyzed the latest measurements offering a hint at what went on in the early universe, and found that only three kinds of theories can account for WMAP’s observations.

Aside from inflation, the other two possible theory categories require more significant leaps of logic and physics, they said. [Images: The Big Bang & Early Universe]

“The takeaway result here is that this idea of inflation turns out to be the only way to do it within the context of standard physics,” Kinney said in a statement. “I think in many ways it puts the idea of inflation on a much stronger footing, because the available alternatives have problems, or weirdnesses, with them.”

For example, alternative explanations must invoke either a speed of sound faster than the speed of light, or energies so high that exotic quantum gravity theories such as string theory would be needed to describe them.

“It may well be that you can come up with a speed of sound faster than the speed of light, but I think people, as a general rule, would be more comfortable with something that doesn’t involve super-luminal propagation,” Kinney said. “Inflation doesn’t require any exotic physics. It’s just standard particle physics.”

Inflation theory still involves a few mind-bending ideas of its own, though. For instance, inflation suggests that during the first 10 to the minus 34 seconds (that’s 0.0000000000000000000000000000000001 seconds), the universe doubled its size at least 90 times.

This would have allowed pairs of matter and antimatter particles to appear out of nothingness, but then move apart from each other so quickly that they wouldn’t have had time to meet and annihilate, as matter and antimatter usually do.

Tiny irregularities in the spread of energy throughout the early universe would have magnified to eventually produce the denser pockets of mass in some areas that allowed gas to condense into stars, forming the galaxies and galaxy clusters that we see today.

The research was first detailed in the November 2011 edition of the Journal of Cosmology and Astroparticle Physics in November 2011 and announced in a public release today (Feb. 27).

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Did Space Radiation Destroy The Russian Mars Probe?

Space radiation most likely caused the demise of a Russian Mars probe that got stuck in Earth orbit shortly after launch and ultimately crashed back to the surface earlier this month, Russia’s Federal Space Agency chief said today (Jan. 31), according to media reports.

Russian space chief Vladimir Popovkin said that an investigation pointed to cosmic radiation as the likely culprit in the failure of the Phobos-Grunt mission, but also suggested that an imported spacecraft component may not have been adequately hardened for the harsh radiation environment in space, reported the Associated Press.

“Two components of the onboard computer system were spontaneously rebooted and it switched into a standby mode,” Popovkin said in a televised remark, according to the Russian news service Ria Novosti. “The most likely reason [for the glitch] is the impact of heavy charged space particles.”

Russia’s Phobos-Grunt space probe malfunctioned shortly after its November 2011 launch, preventing it from continuing on toward Mars.

After being marooned in Earth orbit for more than two months, the Phobos-Grunt fell back to Earth and plunged through the atmosphere on Jan. 15. The $165 million spacecraft reportedly broke apart over the Pacific Ocean, off the coast of Chile.

Popovkin met with Russian Deputy Prime Minister Dmitry Rogozin in the city of Voronezh Tuesday to present the initial findings of an investigation into the Phobos-Grunt failure. Popovkin added that some imported microchips used on Phobos-Grunt may have been low-quality and susceptible to radiation, but he did not give details about where the chips originated, according to the AP. [Photos: Russia's Phobos-Grunt Mission to Mars Moon]

According to Yuri Koptev, a former space agency head who led the Phobos-Grunt investigation, 62 percent of the microchips used in the construction of the Mars probe were considered of an insufficient quality for spaceflight, reported the AP.

Popovkin said that officials involved with the spacecraft’s construction would face punishments for the mismanagement.

Previously, Russian officials claimed everything from accidental radar interference to foreign sabotage was to blame for the demise of Phobos-Grunt.

The ambitious mission was designed to collect soil samples from the Mars moon Phobos and return them back to Earth in 2014. Russian officials have discussed a repeat mission either on their own, or as part of the European Space Agency’s ExoMars project.

“We are holding consultations with the ESA about Russia’s participation in the ExoMars project … If no deal is reached, we will repeat the attempt [to launch a Phobos mission],” Popovkin said, according to another Ria Novosti report.

The Phobos-Grunt failure is one of a string of setbacks suffered by Russia’s Federal Space Agency over the past year.

Most recently, problems were uncovered with the Russian Soyuz spacecraft that is scheduled to take three new crewmembers to the International Space Station in late March, according to the AP.

Popovkin said the launch will be postponed “likely until the end of April” because of the issues, but NASA has yet to announce a new targeted launch date.

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Astronomers To Discuss Material Found Beyond The Solar System Tomorrow

Scientists will announce new findings about material from beyond the solar system at a NASA press conference next Tuesday (Jan. 31).

The researchers will also discuss discoveries about the boundary region that separates our solar system from interstellar space and protects us from fast-moving particles called galactic cosmic rays, researchers said.

The results were obtained after analyzing data gathered by NASA’s Interstellar Boundary Explorer (IBEX) spacecraft, which is studying the edge of the solar system from an orbit about 200,000 miles (322,000 kilometers) above Earth.

The briefing will take place at 1 p.m. EST (1800 GMT) Tuesday at NASA headquarters in Washington, D.C. The participants are:

• David McComas, IBEX principal investigator and assistant vice president of the Space Science and Engineering Division at Southwest Research Institute in San Antonio
• Priscilla Frisch, senior scientist at the University of Chicago
• Eberhard Möbius, professor at the University of New Hampshire and currently visiting professor at Los Alamos National Laboratory in New Mexico
• Seth Redfield, assistant professor at Wesleyan University in Middletown, Conn. NASA launched the coffee-table-sized IBEX probe in October 2008 to map out the boundary between the solar system and interstellar space. The $169 million spacecraft was built for an initial two-year mission.

So far, IBEX has made some surprising discoveries. In 2009, for example, the spacecraft detected a mysterious ribbon on the edge of the solar system that scientists now think is a reflection of the solar wind — the million-miles-per-hour stream of charged particles from the sun.

And in 2010, researchers announced that IBEX had gotten the first-ever look at the solar wind crashing headlong into Earth’s magnetosphere.

Courtesy-Space.com

 

New Horizons Begins The Last Leg Of Its Voyage

A super-speedy NASA probe marks six years of spaceflight today (Jan. 19), beginning the last leg of its journey to the small, faraway world of Pluto.

The New Horizons spacecraft launched Jan. 19, 2006, on a mission to become the first probe to visit the dwarf planet Pluto and its moons. That unprecedented encounter is slated to begin in January 2015, so New Horizons has now entered the home stretch of its nine-year trip, researchers said.

“It’s really around the corner,” said New Horizons principal investigator Alan Stern, of the Southwest Research Institute in Boulder, Colo. “We’re just more and more excited.”

Entering ‘late cruise’ phase

The New Horizons team breaks the spacecraft’s flight to Pluto into three three-year segments, Stern said — early cruise, mid cruise and late cruise.

“We are now turning the corner from mid cruise to late cruise,” Stern told SPACE.com. “We’re really in the final stages.” [Photos of Pluto and Its Moons]

Late cruise should be a busy time for mission scientists and engineers, as they check out the spacecraft’s systems and prepare for the flyby of Pluto and its four known moons. That encounter technically begins in January 2015, Stern said, though closest approach will occur that July, when New Horizons comes within about 6,000 miles (9,600 kilometers) of Pluto.

During the flyby, New Horizons will study Pluto and its moons with seven different instruments, performing the first in-depth reconnaissance of these frigid, far-flung objects.

In fact, researchers have said, the mission will give scientists their first good look at any dwarf planet — a class of bodies suspected to be far more numerous in our solar system than terrestrial and giant planets combined.

 

1 billion miles to go

Pluto is found in the Kuiper Belt, the ring of icy objects beyond Neptune’s orbit. As of today, New Horizons has put about 2.14 billion miles (3.45 billion km) on its odometer, with roughly another 1 billion miles (1.6 billion km) left to go before the close encounter.

The probe’s work won’t be done after it flies by the Pluto system in 2015. The mission team wants New Horizons to study one or two other Kuiper Belt objects as well.

NASA has billed New Horizons as the fastest spacecraft ever launched from Earth. According to the mission team, the probe is now speeding through space at 34,426 mph (55,404 kph) relative to the sun.

While New Horizons spends most of its cruise time hibernating, it’s awake for now. Scientists and engineers are performing various tests on the spacecraft throughout January, Stern said, adding that the spacecraft is in good health.

‘An American story’

The excitement of the New Horizons team has been tempered with some sadness this month, as the scientists mourn the death of Patsy Tombaugh, the widow of Pluto’s discoverer.

Pluto was discovered in 1930 by American astronomer Clyde Tombaugh, who died in 1997. Patsy passed away on Jan. 12 at the age of 99.

Patsy Tombaugh was very enthusiastic about the New Horizons mission, and the team will miss her a great deal, Stern said.

“She was such a wonderful woman,” Stern said. “It was sad to see her pass without getting to see what her husband’s planet really looked like.”

But the Tombaughs’ two children, Annette and Alden, should get to see what New Horizons discovers. They’ll be the mission team’s guests of honor when the probe makes its closest approach to Pluto in July 2015, Stern said.

On top of its technical and scientific ambitions, New Horizons is also part of “a very personal story, an American story,” Stern said. “I think that just makes it nice.”

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Courtesy-Space.com

 

 

Can An Alien Planet Warp Its Solar System

An alien planet circling around a distant star has caused a disk of debris around the system to warp into crookedness, scientists find.

The study could help illuminate the complicated mechanics at work in alien star systems.

Astronomers had originally thought a second planet in the Beta Pictoris system might have caused the warp in the debris disk surrounding the star, but the new study rules out this scenario, scientists say.

The most likely culprit is the star’s first-discovered planet, a Jupiter-sized world known as Beta Pictoris b, researchers said. Though the present orbit of this planet would not create the distortion, new research indicates that the disk itself may have moved the planet from an earlier path that could have altered the shape of the disk. [Gallery: A World of Kepler Alien Planets]

One planet or two?

Gas and debris tend to orbit stars in a smooth plane around their equators, but in the year 2000 astronomers realized that the debris disk around Beta Pictoris was slightly warped.

“The inner part of the disk is tilted, and the outer part, far away from the star, is flat,” Rebekah Dawson, a graduate student at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., told SPACE.com.

Astronomers believed a planet was creating the warp. As such a body moved through the disk, its gravitational effects would change the way the particles within the debris moved, scientists reasoned.

After a decade of searching, astronomers managed to directly image Beta Pictoris b. But, to their surprise, the orbit of the planet seemed to indicate the planet could not have created the tilt.

“If it was causing the warp, we would expect that the planet would be on an inclined orbit,” Dawson said.

Instead, research published in August 2011 by Thayne Currie of NASA revealed that the planet’s orbit was flat, aligned with the outer edge of the disk rather than the interior.

With this in mind, Dawson and her team modeled potential orbits of a second planet and its interactions with Beta Pictoris b, in hopes of finding a path that would explain the observations. However, the researchers were unable to simulate a planet of the right mass at the right distance to cause the warp.

Such a ghost planet would have to have formed the distortion without disrupting the orbit of the existing planet. It would have needed to be small enough to have escaped previous detection, and in a position that wouldn’t have created another bend in the system.

“We considered all different possible masses and distances from the star for other planets, and were able to rule them all out,” Dawson said.

Smaller, more distant planets could exist within the system, but none would be responsible for the distortion, she added.

“The fact that there is a known planet with the mass and distance that it has, means it is not possible for another planet to be making the warp,” Dawson said.

The researchers detailed their findings in a paper published in the December issue of the Astrophysical Journal Letters.

A changing orbit

When Dawson and her team realized the tilt could not have been created by a second planet, they decided to re-examine the first.

If Beta Pictoris b, in its past, had an inclined orbit, it could have sufficiently shifted the dust and rock within the disk. At the same time, friction between the planet and the dust and rock of the disk could have dragged the planet enough to alter its orbit, flattening it into the same plane as the debris.

“The planet is losing energy to the disk as it passes through,” Dawson said.

Such a scenario could reveal a great deal about the history of the disk, which is made up of colliding rocks and dust in the mature system, similar to the Kupier belt and the asteroids between Mars and Jupiter.

“These are the leftover rocky things that didn’t become planets.”

These tiny pieces are too small to see individually, but detailed modeling of the evolution of the system could allow astronomers to study this challenging body.

“It would tell us a lot about the disk and the properties of the planetesimals that are very hard to actually probe,” Dawson said.

 

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Courtesy-Space.com

 

Kepler Finds Habitable Planets

NASA’s planet-hunting Kepler spacecraft has confirmed the discovery of its first alien world in its host star’s habitable zone — that just-right range of distances that could allow liquid water to exist — and found more than 1,000 new explanet candidates, researchers announced today (Dec. 5).

The new finds bring the Kepler space telescope’s total haul to 2,326 potential planets in its first 16 months of operation.These discoveries, if confirmed, would quadruple the current tally of worlds known to exist beyond our solar system, which recently topped 700.

The potentially habitable alien world, a first for Kepler, orbits a star very much like our own sun. The discovery brings scientists one step closer to finding a planet like our own — one which could conceivably harbor life, scientists said.

“We’re getting closer and closer to discovering the so-called ‘Goldilocks planet,’” Pete Worden, director of NASA’s Ames Research Center in Moffett Field, Calif., said during a press conference today. [Gallery: The Strangest Alien Planets]

The newfound planet in the habitable zone is called Kepler-22b. It is located about 600 light-years away, orbiting a sun-like star.

Kepler-22b’s radius is 2.4 times that of Earth, and the two planets have roughly similar temperatures. If the greenhouse effect operates there similarly to how it does on Earth, the average surface temperature on Kepler-22b would be 72 degrees Fahrenheit (22 degrees Celsius).

Hunting down alien planets

The $600 million Kepler observatory launched in March 2009 to hunt for Earth-size alien planets in the habitable zone of their parent stars, where liquid water, and perhaps even life, might be able to exist.

Kepler detects alien planets using what’s called the “transit method.” It searches for tiny, telltale dips in a star’s brightness caused when a planet transits — or crosses in front of — the star from Earth’s perspective, blocking a fraction of the star’s light.

This diagram compares our own solar system to Kepler-22, a star system containing the first “habitable zone” planet discovered by NASA’s Kepler mission.
CREDIT: NASA/Ames/JPL-Caltech

View full size image

The finds graduate from “candidates” to full-fledged planets after follow-up observations confirm that they’re not false alarms. This process, which is usually done with large, ground-based telescopes, can take about a year.

The Kepler team released data from its first 13 months of operation back in February, announcing that the instrument had detected 1,235 planet candidates, including 54 in the habitable zone and 68 that are roughly Earth-size.

Of the total 2,326 candidate planets that Kepler has found to date, 207 are approximately Earth-size. More of them, 680, are a bit larger than our planet, falling into the “super-Earth” category. The total number of candidate planets in the habitable zones of their stars is now 48.

To date, just over two dozen of these potential exoplanets have been confirmed, but Kepler scientists have estimated that at least 80 percent of the instrument’s discoveries should end up being the real deal.

More discoveries to come

The newfound 1,094 planet candidates are the fruit of Kepler’s labors during its first 16 months of science work, from May 2009 to September 2010. And they won’t be the last of the prolific instrument’s discoveries.

“This is a major milestone on the road to finding Earth’s twin,” Douglas Hudgins, Kepler program scientist at NASA headquarters in Washington, D.C., said in a statement.

Mission scientists still need to analyze data from the last two years and on into the future. Kepler will be making observations for a while yet to come; its nominal mission is set to end in November 2012, but the Kepler team is preparing a proposal to extend the instrument’s operations for another year or more.

Kepler’s finds should only get more exciting as time goes on, researchers say.

“We’re pushing down to smaller planets and longer orbital periods,” said Natalie Batalha, Kepler deputy science team lead at Ames.

To flag a potential planet, the instrument generally needs to witness three transits. Planets that make three transits in just a few months must be pretty close to their parent stars; as a result, many of the alien worlds Kepler spotted early on have been blisteringly hot places that aren’t great candidates for harboring life as we know it.

Given more time, however, a wealth of more distantly orbiting — and perhaps more Earth-like — exoplanets should open up to Kepler. If intelligent aliens were studying our solar system with their own version of Kepler, after all, it would take them three years to detect our home planet.

“We are getting very close,” Batalha said. “We are homing in on the truly Earth-size, habitable planets.”

 

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Courtesy-Space.com

 

 

Did Dark Energy Play A Major Role In The Early Universe?

Scientists trying to understand dark energy, one of the weirdest things in the universe, have made a step forward in determining how much of it could have existed shortly after the Big Bang.

Dark energy is the mysterious force scientists think is responsible for pulling space apart at the seams, causing the expansion of the universe to accelerate. No one knows what dark energy is, and it hasn’t been detected directly.

In the new study, researchers used the South Pole Telescope in Antarctica to observe the cosmic microwave background, the pervasive light left over from the Big Bang that is believed to have kick-started the universe. This radiation holds a record of many properties of the early universe, allowing scientists to deduce the maximum amount of dark energy that could have been present at the time.

Based on their measurements, the researchers found that dark energy could not have accounted for more than 1.8 percent of the total density of the universe. By contrast, dark energy dominates space today, accounting for about 74 percent of all the matter and energy in the universe.

Dark energy’s cosmic role

One of the most popular theories of dark energy regards it as the cosmological constant, a term from Einstein’s equations of general relativity.

If dark energy is a constant, then its density — the amount of dark energy per given area of space — hasn’t changed over time. Meanwhile, the density of matter in the universe has changed, becoming lower and lower as the universe has expanded. [Images: The Big Bang & Early Universe]

So, while dark energy now outnumbers matter by about three to one, that ratio would have been much smaller when the young universe was so dense with matter. Dark energy would have been extremely insignificant by comparison.

What is dark energy, really?

The new measurements are consistent with that idea, though they still can’t serve to separate the cosmological constant theory from other models suggesting the early portion of dark energy, though small, was not negligible.

Study lead author Christian L Reichardt, a cosmologist at the University of California, Berkeley, said models in which dark energy is non-constant “have some theoretical advantages.”

For example, he said, they can accommodate an odd coincidence: We happen to find ourselves in a universe where dark energy and matter are relatively comparable, without either completely dominating the other. These theories skirt around that issue by suggesting that the universe hasn’t always been that way.

Christof Wetterich of Heidelberg University in Germany, who in 1987 proposed a model of changing dark energy called “quintessence,” said it is difficult to rule out such models, since they do not lead to a specific prediction for the amount of dark energy at a given time.

“In any case, no deviation from a simple model with a cosmological constant is seen in the data [from the South Pole Telescope], and this is impressive by itself,” Wetterich told SPACE.com in an email. “There can be at most a rather small fraction of early dark energy, consistent with the results of earlier investigations.”

Overall, many cosmologists favor the cosmological constant theory.

“There’s a theorem that the simplest explanation is best, and the cosmological constant right now is the simplest model that matches all the observations,” Reichardt said.

Taking aim at dark energy mystery

As scientists collect better and better data about the cosmic microwave background from experiments like ones using the South Pole Telescope or the European Planck satellite, the situation should become clearer.

“This is an interesting paper,” astrophysicist Bharat Ratra of Kansas State University wrote in an email. Ratra, who was not involved in the study, is the architect, along with Princeton University’s Jim Peebles, of a time-varying model for dark energy.

“Einstein’s cosmological constant is very consistent with observational constraints from combinations of currently available data,” Ratra said, “but dark energy that decreases slowly in time (and varies weakly in space), as in the model Peebles and I considered, is not yet strongly disfavored by the data.

“The situation is likely to become much clearer in the next few years; these are interesting times for cosmology!”

Reichardt and his colleagues have submitted their study to the Astrophysical Journal Letters, where it is currently undergoing peer review, and they posted it to the astronomy preprint site ArXiv.

 

 

Courtesy-Space.com

How Did The Big Bang Happen?

Our universe was born about 13.7 billion years ago in a massive expansion that blew space up like a gigantic balloon.

That, in a nutshell, is the Big Bang theory, which virtually all cosmologists and theoretical physicists endorse. The evidence supporting the idea is extensive and convincing. We know, for example, that the universe is still expanding even now, at an ever-accelerating rate.

Scientists have also discovered a predicted thermal imprint of the Big Bang, the universe-pervading cosmic microwave background radiation. And we don’t see any objects obviously older than 13.7 billion years, suggesting that our universe came into being around that time.

“All of these things put the Big Bang on an extremely solid foundation,” said astrophysicist Alex Filippenko of the University of California, Berkeley. “The Big Bang is an enormously successful theory.”

So what does this theory teach us? What really happened at the birth of our universe, and how did it take the shape we observe today? [Infographic Tour: History & Structure of the Universe]

The beginning

Traditional Big Bang theory posits that our universe began with a singularity — a point of infinite density and temperature whose nature is difficult for our minds to grasp. However, this may not accurately reflect reality, researchers say, because the singularity idea is based on Einstein’s theory of general relativity.

“The problem is, there’s no reason whatsoever to believe general relativity in that regime,” said Sean Carroll, a theoretical physicist at Caltech. “It’s going to be wrong, because it doesn’t take into account quantum mechanics. And quantum mechanics is certainly going to be important once you get to that place in the history of the universe.”

So the very beginning of the universe remains pretty murky. Scientists think they can pick the story up at about 10 to the minus 36 seconds — one trillionth of a trillionth of a trillionth of a second — after the Big Bang.

At that point, they believe, the universe underwent an extremely brief and dramatic period of inflation, expanding faster than the speed of light. It doubled in size perhaps 100 times or more, all within the span of a few tiny fractions of a second. [The Big Bang to Now in 10 Easy Steps]

(Inflation may seem to violate the theory of special relativity, but that’s not the case, scientists say. Special relativity holds that no information or matter can be carried between two points in space faster than the speed of light. But inflation was an expansion of space itself.)

“Inflation was the ‘bang’ of the Big Bang,” Filippenko told SPACE.com “Before inflation, there was just a little bit of stuff, quite possibly, expanding just a little bit. We needed something like inflation to make the universe big.”

This rapidly expanding universe was pretty much empty of matter, but it harbored huge amounts of dark energy, the theory goes. Dark energy is the mysterious force that scientists think is driving the universe’s current accelerating expansion.

During inflation, dark energy made the universe smooth out and accelerate. But it didn’t stick around for long.

“It was just temporary dark energy,” Carroll told SPACE.com. “It converted into ordinary matter and radiation through a process called reheating. The universe went from being cold during inflation to being hot again when all the dark energy went away.”

Scientists don’t know what might have spurred inflation. That remains one of the key questions in Big Bang cosmology, Filippenko said.

Another idea

Most cosmologists regard inflation as the leading theory for explaining the universe’s characteristics — specifically, why it’s relatively flat and homogeneous, with roughly the same amount of stuff spread out equally in all directions.

Various lines of evidence point toward inflation being a reality, said theoretical physicist Andy Albrecht of the University of California, Davis. [Images: Peering Back to the Big Bang]

“They all hang together pretty nicely with the inflationary picture,” said Albrecht, one of the architects of inflation theory. “Inflation has done incredibly well.”

However, inflation is not the only idea out there that tries to explain the universe’s structure. Theorists have come up with another one, called the cyclic model, which is based on an earlier concept called the ekpyrotic universe.

This idea holds that our universe didn’t emerge from a single point, or anything like it. Rather, it “bounced” into expansion — at a much more sedate pace than the inflation theory predicts — from a pre-existing universe that had been contracting. If this theory is correct, our universe has likely undergone an endless succession of “bangs” and “crunches.”

“The beginning of our universe would have been nice and finite,” said Burt Ovrut of the University of Pennsylvania, one of the originators of ekpyrotic theory.

The cyclic model posits that our universe consists of 11 dimensions, only four of which we can observe (three of space and one of time). Our four-dimensional part of the universe is called a brane (short for membrane).

There could be other branes lurking out there in 11-dimensional space, the idea goes. A collision between two branes could have jolted the universe from contraction to expansion, spurring the Big Bang we see evidence of today.

Looking for gravitational waves

Soon, scientists may know for sure which theory — inflation or the cyclic model — is a better representation of reality.

For example, inflation likely would produce much stronger gravitational waves than an ekpyrotic “bounce,” Filippenko said. So researchers are looking for any signs of these theoretical distortions of space time, which have yet to be observed.

The European Space Agency’s Planck satellite, which launched in 2009, may find the elusive gravitational waves. It may also gather other evidence that could tip the scales either way, Ovrut said.

“These are things that, within the next 10 years, will be discussed and hopefully decided,” Ovrut told SPACE.com.

The universe we know takes shape

Cosmologists suspect that the four forces that rule the universe — gravity, electromagnetism and the weak and strong nuclear forces — were unified into a single force at the universe’s birth, squashed together because of the extreme temperatures and densities involved.

But things changed as the universe expanded and cooled. Around the time of inflation, the strong force likely separated out. And by about 10 trillionths of a second after the Big Bang, the electromagnetic and weak forces became distinct, too.

Just after inflation, the universe was likely filled with a hot, dense plasma. But by around 1 microsecond (10 to the minus 6 seconds) or so, it had cooled enough to allow the first protons and neutrons to form, researchers think.

In the first three minutes after the Big Bang, these protons and neutrons began fusing together, forming deuterium (also known as heavy hydrogen). Deuterium atoms then joined up with each other, forming helium-4.

Recombination: The universe becomes transparent

These newly created atoms were all positively charged, as the universe was still too hot to favor the capture of electrons.

But that changed about 380,000 years after the Big Bang. In an epoch known as recombination, hydrogen and helium ions began snagging electrons, forming electrically neutral atoms. Light scatters significantly off free electrons and protons, but much less so off neutral atoms. So photons were now much more free to cruise through the universe.

Recombination dramatically changed the look of the universe; it had been an opaque fog, and now it became transparent. The cosmic microwave background radiation we observe today dates from this era. [Video: Fog of Early Universe Seen]

But still, the universe was pretty dark for a long time after recombination, only truly lighting up when the first stars began shining about 300 million years after the Big Bang. They helped undo much of what recombination had accomplished. These early stars — and perhaps some other mystery sources — threw off enough radiation to split most of the universe’s hydrogen back into its constituent protons and electrons.

This process, known as reionization, seems to have run its course by around 1 billion years after the Big Bang. The universe is not opaque today, as it was before recombination, because it has expanded so much. The universe’s matter is very dilute, and photon scattering interactions are thus relatively rare, scientists say.

Over time, stars gravitated together to form galaxies, leading to more and more large-scale structure in the universe. Planets coalesced around some newly forming stars, including our own sun. And 3.8 billion years ago, life took root on Earth.

Before the Big Bang?

While much about the universe’s first few moments remains speculative, the question of what preceded the Big Bang is even more mysterious and hard to tackle.

For starters, the question itself may be nonsensical. If the universe came from nothing, as some theorists believe, the Big Bang marks the instant when time itself began. In that case, there would be no such thing as “before,” Carroll said.

But some conceptions of the universe’s birth can propose possible answers. The cyclic model, for example, suggests that a contracting universe preceded our expanding one. Carroll, as well, can imagine something existing before the Big Bang.

“It could just be empty space that existed before our Big Bang happened, then some quantum fluctuation gave birth to a universe like ours,” he said. “You can imagine a little bubble of space pinching off through a fluctuation and being filled with just a little tiny dollop of energy, which can then grow into the universe that we see through inflation.”

Filippenko also suspects something along those lines might be true.

“I think time in our universe started with the Big Bang, but I think we were a fluctuation from a predecessor, a mother universe,” Filippenko said.

Will we ever know?

Cosmologists and physicists are working hard to refine their theories and bring the universe’s earliest moments into sharper and sharper focus. But will they ever truly know what happened at the Big Bang?

It’s a daunting challenge, especially since researchers are working at a 13.7-billion-year remove. But don’t count science out, Carroll said. After all, 100 years ago, people understood very little about the universe. We didn’t know about general relativity, for example, or quantum mechanics. We didn’t know the universe was expanding, and we didn’t know about the Big Bang.

“We know all these things now,” Carroll said. “The pace of progress is actually astonishingly fast, so I would never give in to pessimism. There’s no reason in the recent history of cosmology and physics to be pessimistic about our prospects for understanding the Big Bang.”

Albrecht voiced similar optimism, saying we may one day even figure out what, if anything, existed before the Big Bang.

“I base my hope on the fact that cosmology has been so successful,” he told SPACE.com. “It seems nature has sent us a clear message that we really can do science with the universe.”

 

 

Courtesy-Space.com by Mike Wall

 

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