Category Archives: Physics

Matter inside a neutron star is so dense that a teaspoonful would weigh a billion tons

Science News reports: On astrophysicists’ charts of star stuff, there’s a substance that still merits the label “here be dragons.” That poorly understood material is found inside neutron stars — the collapsed remnants of once-mighty stars — and is now being mapped out, as scientists better characterize the weird matter.

The detection of two colliding neutron stars, announced in October (SN: 11/11/17, p. 6), has accelerated the pace of discovery. Since the event, which scientists spied with gravitational waves and various wavelengths of light, several studies have placed new limits on the sizes and masses possible for such stellar husks and on how squishy or stiff they are.

“The properties of neutron star matter are not very well known,” says physicist Andreas Bauswein of the Heidelberg Institute for Theoretical Studies in Germany. Part of the problem is that the matter inside a neutron star is so dense that a teaspoonful would weigh a billion tons, so the substance can’t be reproduced in any laboratory on Earth.

In the collision, the two neutron stars merged into a single behemoth. This remnant may have immediately collapsed into a black hole. Or it may have formed a bigger, spinning neutron star that, propped up by its own rapid rotation, existed for a few milliseconds — or potentially much longer — before collapsing. The speed of the object’s demise is helping scientists figure out whether neutron stars are made of material that is relatively soft, compressing when squeezed like a pillow, or whether the neutron star stuff is stiff, standing up to pressure. This property, known as the equation of state, determines the radius of a neutron star of a particular mass. [Continue reading…]

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The physics of life

Jeremy England writes: Living things are so impressive that they’ve earned their own branch of the natural sciences, called biology. From the perspective of a physicist, though, life isn’t different from non-life in any fundamental sense. Rocks and trees, cities and jungles, are all just collections of matter that move and change shape over time while exchanging energy with their surroundings. Does that mean physics has nothing to tell us about what life is and when it will appear? Or should we look forward to the day that an equation will finally leap off the page like a mathematical Frankenstein’s monster, and say, once and for all, that this is what it takes to make something live and breathe?

As a physicist, I prefer to chart a course between reductionism and defeat by thinking about the probability of matter becoming more life-like. The starting point is to see that there are many separate behaviours that seem to distinguish living things. They harvest energy from their surroundings and use it as fuel to make copies of themselves, for example. They also sense, and even predict things about the world they live in. Each of these behaviours is distinctive, yes, but also limited enough to be able to conceive of a non-living thing that accomplishes the same task. Although fire is not alive, it might be called a primitive self-replicator that ‘copies’ itself by spreading. Now the question becomes: can physics improve our understanding of these life-like behaviours? And, more intriguingly, can it tell us when and under what conditions we should expect them to emerge?

Increasingly, there’s reason to hope the answer might be yes. The theoretical research I do with my colleagues tries to comprehend a new aspect of life’s evolution by thinking of it in thermodynamic terms. When we conceive of an organism as just a bunch of molecules, which energy flows into, through and out of, we can use this information to build a probabilistic model of its behaviour. From this perspective, the extraordinary abilities of living things might turn out to be extreme outcomes of a much more widespread process going on all over the place, from turbulent fluids to vibrating crystals – a process by which dynamic, energy-consuming structures become fine-tuned or adapted to their environments. Far from being a freak event, finding something akin to evolving lifeforms might be quite likely in the kind of universe we inhabit – especially if we know how to look for it. [Continue reading…]

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Neutron star collision showers the universe with a wealth of discoveries

 

Science News reports: Two ultradense cores of dead stars have produced a long-awaited cosmic collision, showering scientists with riches.

The event was the first direct sighting of a smashup of neutron stars, which are formed when aging stars explode and leave behind a neutron-rich remnant. In the wake of the collision, the churning residue forged gold, silver, platinum and a smattering of other heavy elements such as uranium, researchers reported October 16 at a news conference in Washington, D.C. Such elements’ birthplaces were previously unknown, but their origins were revealed by the cataclysm’s afterglow.

“It really is the last missing piece” of the periodic table, says Anna Frebel, an astronomer at MIT who was not involved in the research. “This is heaven for anyone working in the field.” After the collision, about 10 times the Earth’s mass in gold was spewed out into space, some scientists calculated.

Using data gathered by about 70 different observatories, astronomers characterized the event in exquisite detail, releasing a slew of papers describing the results. A tremor of gravitational waves, spotted by the Advanced Laser Interferometer Gravitational-Wave Observatory, LIGO, on August 17, provided the first sign of the cataclysm. [Continue reading…]

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Astronomers find half of the missing matter in the universe

The Guardian reports: It is one of cosmology’s more perplexing problems: that up to 90% of the ordinary matter in the universe appears to have gone missing.

Now astronomers have detected about half of this missing content for the first time, in a discovery that could resolve a long-standing paradox.

The conundrum first arose from measurements of radiation left over from the Big Bang, which allowed scientists to calculate how much matter there is in the universe and what form it takes. This showed that about 5% of the mass in the universe comes in the form of ordinary matter, with the rest being accounted for by dark matter and dark energy.

Dark matter has never been directly observed and the nature of dark energy is almost completely mysterious, but even tracking down the 5% of ordinary stuff has proved more complicated than expected. When scientists have counted up all the observable objects in the sky – stars, planets, galaxies and so on – this only seems to account for between a 10th and a fifth of what ought to be out there.

The deficit is known as the “missing baryon problem”, baryons being ordinary subatomic particles like protons and neutrons.

Richard Ellis, a professor of astrophysics at the University College London, said: “People agree that there’s a lot missing, raising the question where is it?” [Continue reading…]

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Microbes that eat electricity

Emily Singer writes: [In 2015], biophysicist Moh El-Naggar and his graduate student Yamini Jangir plunged beneath South Dakota’s Black Hills into an old gold mine that is now more famous as a home to a dark matter detector. Unlike most scientists who make pilgrimages to the Black Hills these days, El-Naggar and Jangir weren’t there to hunt for subatomic particles. They came in search of life.

In the darkness found a mile underground, the pair traversed the mine’s network of passages in search of a rusty metal pipe. They siphoned some of the pipe’s ancient water, directed it into a vessel, and inserted a variety of electrodes. They hoped the current would lure their prey, a little-studied microbe that can live off pure electricity.

The electricity-eating microbes that the researchers were hunting for belong to a larger class of organisms that scientists are only beginning to understand. They inhabit largely uncharted worlds: the bubbling cauldrons of deep sea vents; mineral-rich veins deep beneath the planet’s surface; ocean sediments just a few inches below the deep seafloor. The microbes represent a segment of life that has been largely ignored, in part because their strange habitats make them incredibly difficult to grow in the lab.

Yet early surveys suggest a potential microbial bounty. A recent sampling of microbes collected from the seafloor near Catalina Island, off the coast of Southern California, uncovered a surprising variety of microbes that consume or shed electrons by eating or breathing minerals or metals. El-Naggar’s team is still analyzing their gold mine data, but he says that their initial results echo the Catalina findings. Thus far, whenever scientists search for these electron eaters in the right locations — places that have lots of minerals but not a lot of oxygen — they find them. [Continue reading…]

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A new technology for detecting neutrinos represents a ‘monumental’ advance for science

Scientific American reports: Neutrinos are famously antisocial. Of all the characters in the particle physics cast, they are the most reluctant to interact with other particles. Among the hundred trillion neutrinos that pass through you every second, only about one per week actually grazes a particle in your body.

That rarity has made life miserable for physicists, who resort to building huge underground detector tanks for a chance at catching the odd neutrino. But in a study published today in Science, researchers working at Oak Ridge National Laboratory (ORNL) detected never-before-seen neutrino interactions using a detector the size of a fire extinguisher. Their feat paves the way for new supernova research, dark matter searches and even nuclear nonproliferation monitoring.

Under previous approaches, a neutrino reveals itself by stumbling across a proton or neutron amidst the vast emptiness surrounding atomic nuclei, producing a flash of light or a single-atom chemical change. But neutrinos deign to communicate with other particles only via the “weak” force—the fundamental force that causes radioactive materials to decay. Because the weak force operates only at subatomic distances, the odds of a tiny neutrino bouncing off of an individual neutron or proton are minuscule. Physicists must compensate by offering thousands of tons of atoms for passing neutrinos to strike. [Continue reading…]

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First support for a physics theory of life

Natalie Wolchover writes: The biophysicist Jeremy England made waves in 2013 with a new theory that cast the origin of life as an inevitable outcome of thermodynamics. His equations suggested that under certain conditions, groups of atoms will naturally restructure themselves so as to burn more and more energy, facilitating the incessant dispersal of energy and the rise of “entropy” or disorder in the universe. England said this restructuring effect, which he calls dissipation-driven adaptation, fosters the growth of complex structures, including living things. The existence of life is no mystery or lucky break, he told Quanta in 2014, but rather follows from general physical principles and “should be as unsurprising as rocks rolling downhill.”

Since then, England, a 35-year-old associate professor at the Massachusetts Institute of Technology, has been testing aspects of his idea in computer simulations. The two most significant of these studies were published this month — the more striking result in the Proceedings of the National Academy of Sciences (PNAS) and the other in Physical Review Letters (PRL). The outcomes of both computer experiments appear to back England’s general thesis about dissipation-driven adaptation, though the implications for real life remain speculative.

“This is obviously a pioneering study,” Michael Lässig, a statistical physicist and quantitative biologist at the University of Cologne in Germany, said of the PNAS paper written by England and an MIT postdoctoral fellow, Jordan Horowitz. It’s “a case study about a given set of rules on a relatively small system, so it’s maybe a bit early to say whether it generalizes,” Lässig said. “But the obvious interest is to ask what this means for life.”

The paper strips away the nitty-gritty details of cells and biology and describes a simpler, simulated system of chemicals in which it is nonetheless possible for exceptional structure to spontaneously arise — the phenomenon that England sees as the driving force behind the origin of life. “That doesn’t mean you’re guaranteed to acquire that structure,” England explained. The dynamics of the system are too complicated and nonlinear to predict what will happen. [Continue reading…]

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Half the atoms inside and around us came from outside the Milky Way

The Guardian reports: Nearly half of the atoms that make up our bodies may have formed beyond the Milky Way and travelled to the solar system on intergalactic winds driven by giant exploding stars, astronomers claim.

The dramatic conclusion emerges from computer simulations that reveal how galaxies grow over aeons by absorbing huge amounts of material that is blasted out of neighbouring galaxies when stars explode at the end of their lives.

Powerful supernova explosions can fling trillions of tonnes of atoms into space with such ferocity that they escape their home galaxy’s gravitational pull and fall towards larger neighbours in enormous clouds that travel at hundreds of kilometres per second.

Astronomers have long known that elements forged in stars can travel from one galaxy to another, but the latest research is the first to reveal that up to half of the material in the Milky Way and similar-sized galaxies can arrive from smaller galactic neighbours.

Much of the hydrogen and helium that falls into galaxies forms new stars, while heavier elements, themselves created in stars and dispersed in the violent detonations, become the raw material for building comets and asteroids, planets and life. [Continue reading…]

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Lawbreaking particles may point to a previously unknown force in the universe

Scientific American reports: For decades physicists have sought signs of misbehaving particles—evidence of subtle cracks in the “Standard Model” of particle physics, the dominant theory describing the most fundamental building blocks of our universe. Although the Standard Model has proved strikingly accurate, scientists have long known some adjustments will be needed. Now, as a recent review paper in Nature documents, experimenters have started seeing suggestions of particles flouting the theory—but they’re not quite the violations theorists were looking for.

The evidence comes from electrons and their more massive cousins, muons and tau leptons. According to the Standard Model, these three particles should behave like differently sized but otherwise identical triplets. But three experiments have produced growing evidence—including results announced in just the last few months—that the particles react differently to some as-yet mysterious influence. The findings are not yet conclusive, but if they hold up, “it would be a complete revolution,” says California Institute of Technology theorist Mark Wise.

A shake-up in the Standard Model would be huge. This theory has formed the bedrock of particle physics research since it was fleshed out in the late 20th century. It carves the universe into twelve elementary particles that make up all matter, plus ‘force-carrier’ particles that transmit the fundamental forces of nature. (For instance, particles exert electrical or magnetic forces by exchanging transient photons.) Despite its successes, however, the Standard Model predicts nothing that would explain gravity or the dark matter thought to invisibly inhabit space. To marry particle physics with these larger-scale observations, theorists have proposed all manner of “new physics”—matter or forces beyond the Standard Model’s menagerie. But most experiments have stubbornly upheld the theory with impressive fidelity, finding no evidence of the hypothesized particles or forces. [Continue reading…]

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We live in a galaxy in the middle of nowhere

Evan Gough writes: Ever since Galileo pointed his telescope at Jupiter and saw moons in orbit around that planet, we began to realize we don’t occupy a central, important place in the Universe. In 2013, a study showed that we may be further out in the boondocks than we imagined. Now, a new study confirms it: we live in a void in the filamental structure of the Universe, a void that is bigger than we thought.

In 2013, a study by University of Wisconsin–Madison astronomer Amy Barger and her student Ryan Keenan showed that our Milky Way galaxy is situated in a large void in the cosmic structure. The void contains far fewer galaxies, stars, and planets than we thought. Now, a new study from University of Wisconsin student Ben Hoscheit confirms it, and at the same time eases some of the tension between different measurements of the Hubble Constant.

The void has a name; it’s called the KBC void for Keenan, Barger and the University of Hawaii’s Lennox Cowie. With a radius of about 1 billion light years, the KBC void is seven times larger than the average void, and it is the largest void we know of. [Continue reading…]

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Sending information without transmitting a signal

Joshua Roebke writes: We connect to each other through particles. Calls and texts ride flecks of light, Web sites and photographs load on electrons. All communication is, essentially, physical. Information is recorded and broadcast on actual objects, even those we cannot see.

Physicists also connect to the world when they communicate with it. They dispatch glints of light toward particles or atoms, and wait for this light to report back. The light interacts with the bits of matter, and how this interaction changes the light reveals a property or two of the bits—although this interaction often changes the bits, too. The term of art for such a candid affair is a measurement.

Particles even connect to each other using other particles. The force of electromagnetism between two electrons is conveyed by particles of light, and quarks huddle inside a proton because they exchange gluons. Physics is, essentially, the study of interactions.

Information is always conveyed through interactions, whether between particles or ourselves. We are compositions of particles who communicate with each other, and we learn about our surroundings by interacting with them. The better we understand such interactions, the better we understand the world and ourselves.

Physicists already know that interactions are local. As with city politics, the influence of particles is confined to their immediate precincts. Yet interactions remain difficult to describe. Physicists have to treat particles as individuals and add complex terms to their solitary existence to model their intimacies with other particles. The resulting equations are usually impossible to solve. So physicists have to approximate even for single particles, which can interact with themselves as a boat rolls in its own wake. Although physicists are meticulous, it is a wonder they ever succeed. Still, their contentions are the most accurate theories we have.

Quantum mechanics is the consummate theory of particles, so it naturally describes measurements and interactions. During the past few decades, as computers have nudged the quantum, the theory has been reframed to encompass information, too. What quantum mechanics implies for measurements and interactions is notoriously bizarre. Its implications for information are stranger still.

One of the strangest of these implications refutes the material basis of communication as well as common sense. Some physicists believe that we may be able to communicate without transmitting particles. In 2013 an amateur physicist named Hatim Salih even devised a protocol, alongside professionals, in which information is obtained from a place where particles never travel. Information can be disembodied. Communication may not be so physical after all.[Continue reading…]

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The inflated debate over cosmic inflation

Amanda Gefter writes: On the morning of Dec. 7, 1979, a 32-year-old Alan Guth woke up with an idea. It had come into his head the previous night, but now, in the light of a California day, he could see the shape of the thing, and was itching to work through the math. He hopped on his bike and rode to his office at the Stanford Linear Accelerator Center. His excitement got him there in record time: 9 minutes, 32 seconds. At his desk, Guth neatly carried out the calculations in his notebook, forming the numbers and symbols in tight, careful lines. Then, at the top of a fresh page, he wrote in all caps: SPECTACULAR REALIZATION.

A year later and some 6,000 miles away, in Moscow, in the middle of the night, Andrei Linde, having read Guth’s paper, had his own spectacular realization. He had been working on his own idea and now he saw how to bring it to life by fixing the difficulties that plagued Guth’s theory. He woke his sleeping wife. “I think I know how the universe was created.”

Guth and Linde had worked out the beginnings of the theory of cosmic inflation. The theory would go through several incarnations over the next few decades, as kinks were worked out and details honed. But the core idea was spectacularly simple: In the earliest fraction of a second of time, a small patch of universe expanded faster than the speed of light, doubling its size again and again, growing a million trillion trillion times bigger in the blink of an eye. A little patch of world, about the size of a dime, grew into our entire observable universe.

What began as a radical notion has now become standard wisdom among physicists—except, notably, Paul Steinhardt, Anna Ijjas, and Avi Loeb. The three physicists recently wrote a scathing article in Scientific American arguing that it’s time to abandon inflation and look for a competing idea. (What idea, you ask? Steinhardt, conveniently, has one that he’s been pushing for decades.) Inflation is too unlikely to occur, too flexible to be confirmed or rejected experimentally, and too messy in its implications, the threesome argued. It “cannot be evaluated using the scientific method.”

It’s not surprising, then, that Guth and Linde—along with physicists David Kaiser and Yasunori Nomura—published a terse response in Scientific American earlier this month defending their theory. What is more surprising, perhaps, is that 29 more of the world’s leading physicists signed it—including four Nobel laureates and a Field’s medalist.

In the media flurry that followed, the disagreement between these groups of physicists was presented as a straight debate, of the kind that often occurs in science when there are multiple interpretations of data. But describing an equivalence between the opinions of Steinhardt, Ijjas, and Loeb on the one hand, and nearly the entirely cosmology community on the other, is a mistake.

The long list of signatories to the recent rebuttal letter in Scientific American puts the lie to the claim that the community is divided. When Ed Witten, Steven Weinberg, Leonard Susskind, Frank Wilczek, Juan Maldacena, Eva Silverstein, Sir Martin Rees, and Stephen Hawking (to name a few) write a letter saying you’ve gotten something wrong … well it’s probably worth considering.

The rebuttal letter also challenges us to understand more clearly why so many scientists are passionate about inflation. What is it about this theory that has the greatest minds in the known universe leaping to its defense? [Continue reading…]

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That the world is not solid but made up of tiny particles is a very ancient insight

Carlo Rovelli writes: According to tradition, in the year 450 BCE, a man embarked on a 400-mile sea voyage from Miletus in Anatolia to Abdera in Thrace, fleeing a prosperous Greek city that was suddenly caught up in political turmoil. It was to be a crucial journey for the history of knowledge. The traveller’s name was Leucippus; little is known about his life, but his intellectual spirit proved indelible. He wrote the book The Great Cosmology, in which he advanced new ideas about the transient and permanent aspects of the world. On his arrival in Abdera, Leucippus founded a scientific and philosophical school, to which he soon affiliated a young disciple, Democritus, who cast a long shadow over the thought of all subsequent times.

Together, these two thinkers have built the majestic cathedral of ancient atomism. Leucippus was the teacher. Democritus, the great pupil who wrote dozens of works on every field of knowledge, was deeply venerated in antiquity, which was familiar with these works. ‘The most subtle of the Ancients,’ Seneca called him. ‘Who is there whom we can compare with him for the greatness, not merely of his genius, but also of his spirit?’ asks Cicero.

What Leucippus and Democritus had understood was that the world can be comprehended using reason. They had become convinced that the variety of natural phenomena must be attributable to something simple, and had tried to understand what this something might be. They had conceived of a kind of elementary substance from which everything was made. Anaximenes of Miletus had imagined this substance could compress and rarefy, thus transforming from one to another of the elements from which the world is constituted. It was a first germ of physics, rough and elementary, but in the right direction. An idea was needed, a great idea, a grand vision, to grasp the hidden order of the world. Leucippus and Democritus came up with this idea.

The idea of Democritus’s system is extremely simple: the entire universe is made up of a boundless space in which innumerable atoms run. Space is without limits; it has neither an above nor a below; it is without a centre or a boundary. Atoms have no qualities at all, apart from their shape. They have no weight, no colour, no taste. ‘Sweetness is opinion, bitterness is opinion; heat, cold and colour are opinion: in reality only atoms, and vacuum,’ said Democritus. Atoms are indivisible; they are the elementary grains of reality, which cannot be further subdivided, and everything is made of them. They move freely in space, colliding with one another; they hook on to and push and pull one another. Similar atoms attract one another and join.

This is the weave of the world. This is reality. Everything else is nothing but a by-product – random and accidental – of this movement, and this combining of atoms. The infinite variety of the substances of which the world is made derives solely from this combining of atoms. [Continue reading…]

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Giant atoms could help unveil ‘dark matter’ and other cosmic secrets

By Diego A. Quiñones, University of Leeds

The universe is an astonishingly secretive place. Mysterious substances known as dark matter and dark energy account for some 95% of it. Despite huge effort to find out what they are, we simply don’t know.

We know dark matter exists because of the gravitational pull of galaxy clusters – the matter we can see in a cluster just isn’t enough to hold it together by gravity. So there must be some extra material there, made up by unknown particles that simply aren’t visible to us. Several candidate particles have already been proposed.

Scientists are trying to work out what these unknown particles are by looking at how they affect the ordinary matter we see around us. But so far it has proven difficult, so we know it interacts only weakly with normal matter at best. Now my colleague Benjamin Varcoe and I have come up with a new way to probe dark matter that may just prove successful: by using atoms that have been stretched to be 4,000 times larger than usual.

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Freeman Dyson on working with the greatest physicists of the 20th century

Steve Paulson writes: One gets the sense that Freeman Dyson has seen everything. It’s not just that at 92 he’s had a front row seat on scientific breakthroughs for the past century, or that he’s been friends and colleagues with many of the giants of 20th-century physics, from Hans Bethe and Wolfgang Pauli to Robert Oppenheimer and Richard Feynman. Dyson is one of the great sages of the science world. If you want to get a sense of where science has come from and where it might be headed, Dyson is your man.

Dyson grew up in England with a gift for numbers and calculating. During World War II, he worked with the British Royal Air Force to pinpoint bombing targets in Germany. After the war, he moved to the United States where he got to know many of the physicists who’d built the atomic bomb. Like a lot of scientists from that era, excitement over the bomb helped launch his career in physics, and later he dreamed of building a fleet of spaceships that would travel around the solar system, powered by nuclear bombs. Perhaps it’s no accident that Dyson became an outspoken critic of nuclear weapons during the Cold War.

For more than six decades, Princeton’s Institute for Advanced Study has been his intellectual home. Dyson has described himself as a fox rather than a hedgehog. He says scientists who jump from one project to the next have more fun. Though no longer an active scientist, he continues to track developments in science and technology. Dyson seems to be happy living in a universe filled with answered questions, and he likes the fact that physics has so far failed to unify the classical world of stars and the quantum world of atoms.

When I approached Dyson about an interview on the idea of the heroic in science, he responded, “I prefer telling stories to talking philosophy.” In the end, I got both stories and big ideas. Dyson isn’t shy about making sweeping pronouncements—whether on the archaic requirements of the Ph.D. system or the pitfalls of Big Science—but his manner is understated and his dry sense of humor is always just below the surface. [Continue reading…]

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There may be two trillion other galaxies

galaxies

Brian Gallagher writes: In 1939, the year Edwin Hubble won the Benjamin Franklin award for his studies of “extra-galactic nebulae,” he paid a visit to an ailing friend. Depressed and interred at Las Encinas Hospital, a mental health facility, the friend, an actor and playwright named John Emerson, asked Hubble what — spiritually, cosmically — he believed in. In Edwin Hubble: Mariner of the Nebulae, Gale E. Christianson writes that Hubble, a Christian-turned-agnostic, “pulled no punches” in his reply. “The whole thing is so much bigger than I am,” he told Emerson, “and I can’t understand it, so I just trust myself to it, and forget about it.”

Even though he was moved by a sense of the universe’s immensity, it’s arresting to recall how small Hubble thought the cosmos was at the time. “The picture suggested by the reconnaissance,” he wrote in his 1937 book, The Observational Approach to Cosmology, “is a sphere, centred on the observer, about 1,000 million light-years in diameter, throughout which are scattered about 100 million nebulae,” or galaxies. “A suitable model,” he went on, “would be furnished by tennis balls, 50 feet apart, scattered through a sphere 5 miles in diameter.” From the instrument later named after him, the Hubble Space Telescope, launched in 1990, we learned from a series of pictures taken, starting five years later, just how unsuitable that model was.

The first is called the Hubble Deep Field, arguably “the most important image ever taken” according to this YouTube video. (I recommend watching it.) The Hubble gazed, for ten days, at an apparently empty spot in the sky, one about the size of a pinhead held up at arm’s length — a fragment one 24-millionth of the whole sky. The resulting picture had 3,000 objects, almost all of them galaxies in various stages of development, and many of them as far away as 12 billion light-years. Robert Williams, the former director of the Space Telescope Science Institute, wrote in the New York Times, “The image is really a core sample of the universe.” Next came the Ultra Deep Field, in 2003 (after a three-month exposure with a new camera, the Hubble image came back with 10,000 galaxies), then the eXtreme Deep Field, in 2012, a refined version of the Ultra that reveals galaxies that formed just 450 million years after the Big Bang. [Continue reading…]

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Colliding black holes tell new story of stars

Natalie Wolchover writes: At a talk last month in Santa Barbara, California, addressing some of the world’s leading astrophysicists, Selma de Mink cut to the chase. “How did they form?” she began.

“They,” as everybody knew, were the two massive black holes that, more than 1 billion years ago and in a remote corner of the cosmos, spiraled together and merged, making waves in the fabric of space and time. These “gravitational waves” rippled outward and, on Sept. 14, 2015, swept past Earth, strumming the ultrasensitive detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO). LIGO’s discovery, announced in February, triumphantly vindicated Albert Einstein’s 1916 prediction that gravitational waves exist. By tuning in to these tiny tremors in space-time and revealing for the first time the invisible activity of black holes — objects so dense that not even light can escape their gravitational pull — LIGO promised to open a new window on the universe, akin, some said, to when Galileo first pointed a telescope at the sky.

Already, the new gravitational-wave data has shaken up the field of astrophysics. In response, three dozen experts spent two weeks in August sorting through the implications at the Kavli Institute for Theoretical Physics (KITP) in Santa Barbara.[Continue reading…]

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Sesame particle accelerator project brings Middle East together

The Guardian reports: In the sleepy hillside town in al-Balqa, not far from the Jordan Valley, a grand project is taking shape. The Middle East’s new particle accelerator – the Synchrotron-Light for Experimental Science and Applications, or Sesame – is being built.

In a region racked by violence, extremism and the disintegration of nation states, Sesame feels a world apart; the meditative peace of the surrounding countryside belying the advanced stages of construction inside the site, which is due to be formally inaugurated next spring, with the first experiments taking place as early as this autumn.

It’s a miracle it got off the ground in the first place. Sesame’s members are Iran, Pakistan, Israel, Turkey, Cyprus, Egypt, the Palestinian Authority, Jordan and Bahrain. Iran and Pakistan do not recognise Israel, nor does Turkey recognise Cyprus, and everyone has their myriad diplomatic spats.

Iran, for example, continues to participate despite two of its scientists who were involved in the project, quantum physicist Masoud Alimohammadi and nuclear scientist Majid Shahriari, being assassinated in operations blamed on Israel’s Mossad.

“We’re cooperating very well together,” said Giorgio Paolucci, the scientific director of Sesame. “That’s the dream.” [Continue reading…]

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