Extensive systems of fossilized riverbeds have been discovered on an ancient region of the Martian surface, supporting the idea that the now cold and dry Red Planet had a warm and wet climate about 4 billion years ago. The University College London research identified over 17,000 kilometers of former river channels on a northern plain called Arabia Terra, providing further evidence of water once flowing on Mars.

"Climate models of early Mars predict rain in Arabia Terra and until now there was little geological evidence on the surface to support this theory. This led some to believe that Mars was never warm and wet but was a largely frozen planet, covered in ice-sheets and glaciers. We've now found evidence of extensive river systems in the area which supports the idea that Mars was warm and wet, providing a more favorable environment for life than a cold, dry planet," explained lead author, Joel Davis (UCL Earth Sciences).

Since the 1970s, scientists have identified valleys and channels on Mars which they think were carved out and eroded by rain and surface runoff, just like on Earth. Similar structures had not been seen on Arabia Terra until the team analysed high resolution imagery from NASA's Mars Reconnaissance Orbiter (MRO) spacecraft.

The new study examined images covering an area roughly the size of Brazil at a much higher resolution than was previously possible - 6 meters per pixel compared to 100 meters per pixel. While a few valleys were identified, the team revealed the existence of many systems of fossilized riverbeds which are visible as inverted channels spread across the Arabia Terra plain (below).

The inverted channels are similar to those found elsewhere on Mars and Earth. They are made of sand and gravel deposited by a river and when the river becomes dry, the channels are left upstanding as the surrounding material erodes. On Earth, inverted channels often occur in dry, desert environments like Oman, Egypt, or Utah, where erosion rates are low - in most other environments, the channels are worn away before they can become inverted.

"The networks of inverted channels in Arabia Terra are about 30m high and up to 1-2km wide, so we think they are probably the remains of giant rivers that flowed billions of years ago. Arabia Terra was essentially one massive flood plain bordering the highlands and lowlands of Mars. We think the rivers were active 3.9-3.7 billion years ago, but gradually dried up before being rapidly buried and protected for billions of years, potentially preserving any ancient biological material that might have been present," added Joel Davis.

"These ancient Martian flood plains would be great places to explore to search for evidence of past life. In fact, one of these inverted channels called Aram Dorsum is a candidate landing site for the European Space Agency's ExoMars Rover mission, which will launch in 2020," said Dr Matthew Balme, Senior Lecturer at The Open University and co-author of the study.

The Daily Galaxy via University College London

Our solar system is in a unique area of the universe that's conducive to life, says John Webb and his colleagues at the University of New South Wales, who have carried out intensive study that threatens to turn the world of theoretical physics upside down.

The team studied the fine structure in the spectral lines of the light from distant quasars from data from the Very Large Telescope (VLT) in Chile with stunning results that showed that one of the constants of nature --the Alpha appears to be different in different parts of the cosmos, supporting the theory that our solar system is in a part of the universe that is "just right" for life, which negates Einstein's equivalence principle, which states that the laws of physics are the same everywhere.

The "magic number," known as Alpha or the fine-structure constant, appears to vary throughout the Universe, concluded the team from the University of New South Wales, Swinburne University of Technology and the University of Cambridge.

"What they found threatens to turn the world of theoretical physics upside down," said theorectical physicist, Paul Davies of Arizona State in an article in Cosmos this past January. "On the face of it, α has slightly different values in different parts of the Universe, implying that the fine structure constant is not a constant at all, but varies over cosmological distances and times."

"This finding in 2015 was a real surprise to everyone," said John Webb of the University of New South Wales in Sydney, Australia. The change in the constant appears to have an orientation, creating a "preferred direction", or axis, across the cosmos, an idea that was dismissed more than 100 years ago with the creation of Einstein's special theory of relativity.

“After measuring alpha in around 300 distant galaxies, a consistency emerged: this magic number, which tells us the strength of electromagnetism, is not the same everywhere as it is here on Earth, and seems to vary continuously along a preferred axis through the Universe,” said Webb.

“The implications for our current understanding of science are profound. If the laws of physics turn out to be merely “local by-laws”, it might be that whilst our observable part of the Universe favors the existence of life and human beings, other far more distant regions may exist where different laws preclude the formation of life, at least as we know it.

“If our results are correct, clearly we shall need new physical theories to satisfactorily describe them.”

The researchers' conclusions are based on new measurements taken with the Very Large Telescope (VLT) in Chile, along with their previous measurements from the world's largest optical telescopes at the Keck Observatory, in Hawaii.

The core finding of the new study is the fine structure constant (alpha). This number determines the strength of interactions between light and matter. A decade ago, Webb used observations from the Keck telescope in Hawaii to analyze the light from distant galaxies called quasars. The data suggested that the value of alpha was very slightly smaller when the quasar light was emitted 12 billion years ago than it appears in laboratories on Earth today.

Webb's colleague Julian King, also of the University of New South Wales, has analyzed data from the Very Large Telescope (VLT) in Chile (below), which looks at a different region of the sky. The VLT data suggests that the value of alpha elsewhere in the Universe is very slightly bigger than on Earth.

The difference in both cases is around a millionth of the value alpha has in our region of space, and suggests that alpha varies in space rather than time. "I'd quietly hoped we'd simply find the same thing that Keck found," King says. "This was a real shock."

King says that after combining the two sets of measurements, the new result "struck" them: "The Keck telescopes and the VLT are in different hemispheres; they look in different directions through the Universe. Looking to the north with Keck we see, on average, a smaller alpha in distant galaxies, but when looking south with the VLT we see a larger alpha.

"It varies by only a tiny amount - about one part in 100,000 - over most of the observable Universe, but it's possible that much larger variations could occur beyond our observable horizon."

Michael Murphy, of Swinburne University of Technology, says the discovery will force scientists to rethink their understanding of Nature's laws.

"The fine structure constant, and other fundamental constants, are absolutely central to our current theory of physics. If they really do vary, we'll need a better, deeper theory," Dr. Murphy says.

While a "varying constant" would shake our understanding of the world around us, Dr. Murphy notes: "Extraordinary claims require extraordinary evidence. What we're finding is extraordinary, no doubt about that.

"It's one of the biggest questions of modern science - are the laws of physics the same everywhere in the Universe and throughout its entire history? We're determined to answer this burning question one way or the other."

The team's analysis of around 300 measurements of alpha in light coming from various points in the sky suggests the variation is not random but structured, like a bar magnet. The Universe seems to have a large alpha on one side and a smaller alpha on the other.

This "dipole" alignment nearly matches that of a stream of galaxies mysteriously moving towards the edge of the Universe. It does not, however, line up with another unexplained dipole, dubbed the axis of evil, in the afterglow of the Big Bang.

Earth sits somewhere in the middle of the extremes for alpha. If correct, the result would explain why alpha seems to have the finely tuned value that allows chemistry and thus biology to occur. Grow alpha by 4 per cent, for instance, and the stars would be unable to produce carbon, making our biochemistry impossible.

If the interpretation of the light is correct, it is "a huge deal", agrees Craig Hogan, head of the Fermilab Center for Particle Astrophysics in Batavia, Illinois. But like Cowie, he told New Scientist that he suspects there is an error somewhere in the analysis. "I think the result is not real," he says.

Michael Murphy of Swinburne University in Australia, a co-author of the paper, says that the evidence for changing constants is piling up. "We just report what we find, and no one has been able to explain away these results in a decade of trying," Murphy told New Scientist. "The fundamental constants being constant is an assumption. We're here to test physics, not to assume it."

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The Daily Galaxy via science.unsw.edu, cosmosmagazine.com,  newscientist.com

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"We really are opening up a whole new way of observing the universe, a way that is going to be central to the human race's exploration of the universe around us, not just for years or decades, but for centuries into the future," said Kip Thorne, Feynman Professor of Theoretical Physics at the California Institute of Technology.

In an extensive interview published online this week, the winners of the 2016 Kavli Prize in Astrophysics discuss their 40-year effort to detect gravitational waves, the elusive ripples in the fabric of space-time that Albert Einstein so boldly predicted. The discussion, with physicists Kip Thorne and Rainer Weiss, covers the challenges of eavesdropping on gravitational waves, why their discovery has captured the world's imagination, and what the future holds for astronomy.

Thorne, Weiss and Ronald Drever co-founded the Laser Interferometer Gravitational-Wave Observatory, known as LIGO. Last year, for the first time, the LIGO experiment registered the signal generated by the collision of two black holes, confirming a central prediction of Einstein's general theory of relativity. A second detection was announced this past June, ushering in a new era of astronomical exploration.

"The first thing [Einstein] would ask about is probably the technology..." said Rainer Weiss, Emeritus Professor of Physics at the Massachusetts Institute of Technology and a member of the LIGO Scientific Collaboration, which operates the twin detectors. "Einstein would be interested in the rest of it, but mainly, 'How did you do it?'"

At the announcement of the epic discovery this February 2016, Thorne said: "With this discovery, we humans are embarking on a marvelous new quest: the quest to explore the warped side of the universe—objects and phenomena that are made from warped spacetime. Colliding black holes and gravitational waves are our first beautiful examples," The image below is Kip Thorne's amazing view of this newly revealed dark side of the universe.

In June 2009, Thorne resigned his Feynman Professorship (becoming the Feynman Professor of Theoretical Physics, Emeritus) in order to ramp up a new career in writing, movies, and continued scientific research. His most recent major movie project was Interstellar. Thorne was the film's science advisor and an executive producer. His principal current research is an exploration of the nonlinear dynamical behaviors of curved spacetime, using computer simulations and analytical calculations.

Thorne's research has focused on gravitation physics and astrophysics, with emphasis on relativistic stars, black holes and gravitational waves. In the late 1960's and early 70's he laid the foundations for the theory of pulsations of relativistic stars and the gravitational waves they emit. During the 70's and 80's he developed mathematical formalism by which astrophysicists analyze the generation of gravitational waves and worked closely with Vladimir Braginsky, Ronald Drever and Rainer Weiss on developing new technical ideas and plans for gravitational wave detection.

Thorne is a co-founder (with Weiss and Drever) of the LIGO (Laser Interferometer Gravitational Wave Observatory) Project and he chaired the steering committee that led LIGO in its earliest years (1984--87). In the 1980s, 90s and 2000s he and his research group have provided theoretical support for LIGO, including identifying gravitational wave sources that LIGO should target, laying foundations for data analysis techniques by which their waves are being sought, designing the baffles to control scattered light in the LIGO beam tubes, and --- in collaboration with Vladimir Braginsky's (Moscow Russia) research group --- inventing quantum-nondemolition designs for advanced gravity-wave detectors.

"We had thought the first signal would be some little small thing poking up out of the noise and we'd have to work really hard to understand what it was," Nergis Mavalvala the Curtis and Kathleen Marble Professor of Astrophysics and the Associate Department Head of Physics at the Massachusetts Institute of Technology (MIT), and a member of the MIT Kavli Institute for Astrophysics and Space Research (MKI). "But in fact, the signal we got is a very clean and beautiful event. It tells us that the binary black holes were located about 1.5 billion light years away. They whirled around each other at nearly the speed of light before a collision that was so powerful, it converted approximately three times the mass of the Sun into gravitational wave energy—in just a few tenths of a second!"

Join StarTalk's Neil deGrasse Tyson to Explore the Epic Discovery of Gravitational Waves (LISTEN)

"This means that the stars are no longer silent," says Matthew Evans is an Assistant Professor of Physics at MIT as well as a member of MKI. His work centers on gravitational wave detector science, The frequencies of gravitational waves that LIGO is designed to detect are actually in the human audible range. So when we're working on LIGO, we often take its output and put it on a speaker and just listen to it. For this binary black hole system, it made a distinctive, rising "whoooop!" sound. It's not that we just look up and see anymore, like we always have—we actually can listen to the universe now. It's a whole new sense, and humanity did not have this sense until LIGO was built."

"We often whistled to demonstrate what we thought these smashing black holes might sound like, and it turns out if you play the piano or a keyboard, you can also make a similar sound," said Rainer Weiss is a Professor of Physics, Emeritus at MIT, among the first to explore the kind of instrumentation necessary to detect gravitational waves and proposed the LIGO project with two colleagues in the 1980s. "Do you know what a glissando is? It's when you run your fingers very quickly across the keys. If you started at the bottom of a keyboard and went all the way to the middle C and then hold that note for a little bit—that's what this black hole signal happened to be. "I keep telling people I'd love to be able to see Einstein's face right now."

The existence of gravitational waves was first demonstrated in the 1970s and 80s by Joseph Taylor, Jr., and colleagues. Taylor and Russell Hulse discovered in 1974 a binary system composed of a pulsar in orbit around a neutron star. Taylor and Joel M. Weisberg in 1982 found that the orbit of the pulsar was slowly shrinking over time because of the release of energy in the form of gravitational waves. For discovering the pulsar and showing that it would make possible this particular gravitational wave measurement, Hulse and Taylor were awarded the Nobel Prize in Physics in 1993.

The Daily Galaxy via Caltech, MIT, Kavli Institute for Astrophysics, and Space Research

Image credit: LIGO detects gravitational waves from merging black holes, LIGO, NSF, Aurore Simonet; Kip Thorne, Interstellar

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On February 11, 2016 the Laser Interferometer Gravitational-Wave Observatory reported that it had discovered gravitational waves, heralding a new field of scientific study. Just a few months later, host Neil deGrasse Tyson and co-host Eugene Mirman took to the stage at the Count Basie Theatre in Red Bank, NJ to explore that discovery with the help of LIGO astrophysicist Dr. Nergis Mavalvala, cosmologist and StarTalk All-Stars host Dr. Janna Levin, and comedian and returning StarTalk Live! guest Michael Showalter.

In Part One, you'll learn exactly how LIGO is able to measure a wave motion 10,000 times smaller than the nucleus of an atom which began 1.3 billion light years away from Earth, and why it's critical to have two different facilities, one in Louisiana and one in Washington, working in tandem. You'll also find out why it took the LIGO team half a century and a billion dollars to discover something Einstein predicted nearly 100 years before, how unexpected the discovery was, and why it took them so long to make the announcement, when they'd actually recorded the event on September 14, 2015.

In Part Two, Neil deGrasse Tyson, Eugene Mirman, cosmologist Janna Levin, LIGO astrophysicist Nergis Mavalvala, and comedian Michael Showalter move from the specifics of how LIGO works to the broader questions of what it can teach us about our universe. You'll explore what kind of events create gravitational waves, like supernovas or the motions of orbiting neutron stars, and just how much energy was actually released when those two black holes collided 1.3 billion years ago. Find out how sensitive a detector would need to be to detect waves from the Big Bang, and why, to detect more subtle signals, we need to move our detectors into space with LISA, the Laser Interferometer Space Antenna. Discover how LIGO lets us detect bare black holes for the first time, rather than just deducing where they are by seeing the destruction of a star they're shredding. Plus, Neil and company grapple with universal expansion, quantum physics, black holes, the speed of light, the origin of spacetime, the death of our Sun, the collision of the Milky Way with the Andromeda Galaxy, and much more.

Listen HERE to LIGO and the Black Hole Blues (Part 1) 

Listen HERE to LIGO and the Black Hole Blues (Part 2)

Astronomers have identified a young star, located almost 11,000 light years away, which could help us understand how the most massive stars in the Universe are formed. This young star, already more than 30 times the mass of our Sun, is still in the process of gathering material from its parent molecular cloud, and may be even more massive when it finally reaches adulthood.

The researchers, led by a team at the University of Cambridge, have identified a key stage in the birth of a very massive star, and found that these stars form in a similar way to much smaller stars like our Sun from a rotating disc of gas and dust. The results will be presented this week at the Star Formation 2016 conference at the University of Exeter, and are reported in the Monthly Notices of the Royal Astronomical Society.

In our galaxy, massive young stars those with a mass at least eight times greater than the Sun are much more difficult to study than smaller stars. This is because they live fast and die young, making them rare among the 100 billion stars in the Milky Way, and on average, they are much further away.

“An average star like our Sun is formed over a few million years, whereas massive stars are formed orders of magnitude faster — around 100,000 years,” said Dr John Ilee from Cambridge's Institute of Astronomy, the study's lead author. “These massive stars also burn through their fuel much more quickly, so they have shorter overall lifespans, making them harder to catch when they are infants.”

The protostar that Ilee and his colleagues identified resides in an infrared dark cloud - a very cold and dense region of space which makes for an ideal stellar nursery. However, this rich star-forming region is difficult to observe using conventional telescopes, since the young stars are surrounded by a thick, opaque cloud of gas and dust. But by using the Submillimeter Array (SMA) in Hawaii and the Karl G Jansky Very Large Array (VLA) in New Mexico, both of which use relatively long wavelengths of light to observe the sky, the researchers were able to ‘see' through the cloud and into the stellar nursery itself.

By measuring the amount of radiation emitted by cold dust near the star, and by using unique fingerprints of various different molecules in the gas, the researchers were able to determine the presence of a ‘Keplerian' disc - one which rotates more quickly at its centre than at its edge.

“This type of rotation is also seen in the Solar System - the inner planets rotate around the Sun more quickly than the outer planets,” said Ilee. “It's exciting to find such a disc around a massive young star, because it suggests that massive stars form in a similar way to lower mass stars, like our Sun.”

The initial phases of this work were part of an undergraduate summer research project at the University of St Andrews, funded by the Royal Astronomical Society (RAS). The undergraduate carrying out the work, Pooneh Nazari, said, “My project involved an initial exploration of the observations, and writing a piece of software to ‘weigh' the central star. I'm very grateful to the RAS for providing me with funding for the summer project — I'd encourage anyone interested in academic research to try one!”

From these observations, the team measured the mass of the protostar to be over 30 times the mass of the Sun. In addition, the disc surrounding the young star was also calculated to be relatively massive, between two and three times the mass of our Sun. Dr Duncan Forgan, also from St Andrews and lead author of a companion paper, said, “Our theoretical calculations suggest that the disc could in fact be hiding even more mass under layers of gas and dust. The disc may even be so massive that it can break up under its own gravity, forming a series of less massive companion protostars.”

The next step for the researchers will be to observe the region with the Atacama Large Millimetre Array (ALMA), located in Chile. This powerful instrument will allow any potential companions to be seen, and allow researchers to learn more about this intriguing young heavyweight in our galaxy.

Rho Cassiopeiae (Rho Cas) shown at the top of the page belongs to an unusual class of stars, a yellow hypergiant of which only seven have been found in the Milky Way. Despite being located some 10,000 light-years (ly) away, the star is visible to the naked eye because it is over 500,000 times more luminous than Sol. With surface temperatures between 3,500 and 7,000 °K, yellow hypergiants appear to be stars that are at a very evolved stage of their life and may be close to exploding as supernovae.

The Daily Galaxy via RAS and University of Cambridge

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