A fundamental challenge
Bill Saxton/NRAO/AUI/NSF

By Joshua Sokol

Imagine you’re an astronomer with bright ideas about the hidden laws of the cosmos. Like any good scientist, you craft an experiment to test your hypothesis.

Then comes bad news – there’s no way to carry it out, except maybe in a computer simulation. For cosmic objects are way too unwieldy for us to grow them in Petri dishes or smash them together as we do with subatomic particles.

Thankfully, though, there are rare places in space where nature has thrown together experiments of its own – like PSR J0337+1715. First observed in 2012 and announced in 2014, this triple system is 4200 light years away in the constellation Taurus.

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July 17, 2017

NASA’s new Neutron star Interior Composition Explorer (NICER) mission to study the densest observable objects in the universe has begun science operations.

Launched June 3 on an 18-month baseline mission, NICER will help scientists understand the nature of the densest stable form of matter located deep in the cores of neutron stars using X-ray measurements.

NICER operates around the clock on the International Space Station (ISS). In the two weeks following launch, NICER underwent extraction from the SpaceX Dragon spacecraft, robotic installation on ExPRESS Logistics Carrier 2 on board ISS and initial deployment. Commissioning efforts began June 14, as NICER deployed from its stowed launch configuration. All systems are functioning as expected.

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The GEO600 gravitational-wave detector in Hanover, Germany, tests technologies that are deployed in larger gravitational-wave observatories such as LIGO.

Physicists find ways to make LIGO and other gravitational-wave detectors even more sensitive.

Elizabeth Gibney
12 July 2017

Gravitational-wave observatories have some of the most sensitive detectors on the planet, which allows them to spot the faint ripples in space-time that pass through Earth from the collisions of massive black holes billions of light years away. But their ability to catch more subtle signals is constrained by fundamental quantum limits. Now physicists are devising tricks to get around this problem. The goal is to peer farther into the Universe and to spot the effects of collisions between less massive objects, such as neutron stars.

The US-based Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) is already planning to use photonics techniques to ‘squeeze’ light. That should increase LIGO’s sensitivity by 50%. Quantum physicists from outside the gravitational-wave community are pitching in with new ideas, too. In Nature this week, they describe a technique that could, in theory, double the sensitivity of detectors (C. B. Møller et al. Nature 547, 191–195; 2017).

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(Image Credits: Chris Klimek)

Jun 27, 2017

by Panos Charitos

Kip Thorne is one of the leading physicists working on Einstein's theory of relativity today. He has pioneered the scientific investigation of black holes in the universe. He was one of the founders of the LIGO project to detect gravitational waves and he has been one of the international team of physicists developing the LISA gravitational wave detector, a project of the space agency ESA which is likely to have some NASA participation. He has carried out important research in an unusually wide range of fields: general relativity, astrophysics, the quantum theory of measurement, time travel, even the experimental details of the design of gravitational wave detectors. Panos Charitos (PC) and Spyros Argyropoulos (SA) met him in Geneva and discussed with him about the new window that gravitational waves open and the cosmological implications of this discovery.

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20 June 2017

The LISA trio of satellites to detect gravitational waves from space has been selected as the third large-class mission in ESA’s Science programme, while the Plato exoplanet hunter moves into development.

These important milestones were decided upon during a meeting of ESA’s Science Programme Committee today, and ensure the continuation of ESA’s Cosmic Vision plan through the next two decades.

The ‘gravitational universe’ was identified in 2013 as the theme for the third large-class mission, L3, searching for ripples in the fabric of spacetime created by celestial objects with very strong gravity, such as pairs of merging black holes.

Predicted a century ago by Albert Einstein's general theory of relativity, gravitational waves remained elusive until the first direct detection by the ground-based Laser Interferometer Gravitational-Wave Observatory in September 2015. That signal was triggered by the merging of two black holes some 1.3 billion light-years away. Since then, two more events have been detected.

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Image Credit: Virgo Collaboration

17 June 2017 -- For the first time, all three second generation interferometers---LIGO Hanford, LIGO Livingston, and Virgo---are simultaneously in a locked state. (When an interferometer is "locked" it means that an optical resonance is set up in the arm cavities and is producing a stable interference pattern at the photodetector.) Virgo is joining in an engineering mode, in preparation for the full triple-observing mode planned for later this summer. Congratulations, Virgo! - See more at:

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BEATRICE DE GEA FOR THE NEW YORK TIMES

James H. Simons likes to play against type. He is a billionaire star of mathematics and private investment who often wins praise for his financial gifts to scientific research and programs to get children hooked on math.

But in his Manhattan office, high atop a Fifth Avenue building in the Flatiron district, he’s quick to tell of his career failings.

He was forgetful. He was demoted. He found out the hard way that he was terrible at programming computers. “I’d keep forgetting the notation,” Dr. Simons said. “I couldn’t write programs to save my life.”

After that, he was fired.

His message is clearly aimed at young people: If I can do it, so can you.

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This illustration reveals how the gravity of a white dwarf star warps space and bends the light of a distant star behind it. Credit: NASA, ESA, and A. Feild (STScI)

June 7, 2017

Albert Einstein predicted that whenever light from a distant star passes by a closer object, gravity acts as a kind of magnifying lens, brightening and bending the distant starlight. Yet, in a 1936 article in the journal Science, he added that because stars are so far apart "there is no hope of observing this phenomenon directly."

Now, an international research team directed by Kailash C. Sahu has done just that, as described in their June 9, 2017 article in Science. The study is believed to be the first report of a particular type of Einstein's "gravitational microlensing" by a star other than the sun.

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This image shows the configuration of NICER's 56 X-ray mirrors that will gather scientific observations and play an instrumental role in demonstration X-ray navigation. Credit: NASA

Nearly 50 years after British astrophysicist Jocelyn Bell discovered the existence of rapidly spinning neutron stars, NASA will launch the world's first mission devoted to studying these unusual objects.

The agency also will use the same platform to carry out the world's first demonstration of X-ray navigation in space.
The agency plans to launch the two-in-one Neutron Star Interior Composition Explorer, or NICER, aboard SpaceX CRS-11, a cargo resupply mission to the International Space Station to be launched aboard a Falcon 9 rocket.
About a week after its installation as an external attached payload, this one-of-a-kind investigation will begin observing neutron stars, the densest objects in the universe. The mission will focus especially on pulsars—those neutron stars that appear to wink on and off because their spin sweeps beams of radiation past us, like a cosmic lighthouse.

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Results confirm new population of black holes

The Laser Interferometer Gravitational-wave Observatory (LIGO) has made a third detection of gravitational waves, ripples in space and time, demonstrating that a new window in astronomy has been firmly opened. As was the case with the first two detections, the waves were generated when two black holes collided to form a larger black hole.

GW170104 black hole size comparison
Schematic showing the relative 'sizes' (in Rs) of the black holes before and after merging.
The newfound black hole, formed by the merger, has a mass about 49 times that of our sun. This fills in a gap between the masses of the two merged black holes detected previously by LIGO, with solar masses of 62 (first detection) and 21 (second detection).

"We have further confirmation of the existence of stellar-mass black holes that are larger than 20 solar masses—these are objects we didn't know existed before LIGO detected them," says MIT's David Shoemaker, the newly elected spokesperson for the LIGO Scientific Collaboration (LSC), a body of more than 1,000 international scientists who perform LIGO research together with the European-based Virgo Collaboration. "It is remarkable that humans can put together a story, and test it, for such strange and extreme events that took place billions of years ago and billions of light-years distant from us. The entire LIGO and Virgo scientific collaborations worked to put all these pieces together."

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THREE OF A KIND Scientists have made a third detection of gravitational waves. A pair of black holes, shown above, fused into one, in a powerful collision about 3 billion light-years from Earth. That smashup churned up ripples in spacetime that were detected by the LIGO experiment.

Spacetime vibrations arrive from black hole collision 3 billion light-years away
BY EMILY CONOVER 11:00AM, JUNE 1, 2017

For a third time, scientists have detected the infinitesimal reverberations of spacetime: gravitational waves.

Two black holes stirred up the spacetime wiggles, orbiting one another and spiraling inward until they fused into one jumbo black hole with a mass about 49 times that of the sun. Ripples from that union, which took place about 3 billion light-years from Earth, zoomed across the cosmos at the speed of light, eventually reaching the Advanced Laser Interferometer Gravitational-Wave Observatory, LIGO, which detected them on January 4.

“These are the most powerful astronomical events witnessed by human beings,” Michael Landry, head of LIGO’s Hanford, Wash., observatory, said during a news conference May 31 announcing the discovery. As the black holes merged, they converted about two suns’ worth of mass into energy, radiated as gravitational waves.

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May 26, 2017

A new NASA mission is headed for the International Space Station next month to observe one of the strangest observable objects in the universe.

Launching June 1, the Neutron Star Interior Composition Explorer (NICER) will be installed aboard the space station as the first mission dedicated to studying neutron stars, a type of collapsed star that is so dense scientists are unsure how matter behaves deep inside it.

A neutron star begins its life as a star between about seven and 20 times the mass of our sun. When this type of star runs out of fuel, it collapses under its own weight, crushing its core and triggering a supernova explosion. What remains is an ultra-dense sphere only about 12 miles (20 kilometers) across, the size of a city, but with up to twice the mass of our sun squeezed inside. On Earth, one teaspoon of neutron star matter would weigh a billion tons.

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By Don Lincoln
Updated 1504 GMT (2304 HKT) May 14, 2017

(CNN)A recent astronomical observation of a "cold spot" in the universe is stirring the interest of scientists who are intrigued with an exciting and highly speculative theory that there may be more than one universe.

Now before you get incredibly excited about that prospect, I should caution that this particular explanation is a huge long shot and there are more prosaic possible explanations. The idea of multiple universes, or multiverses, is a highly speculative and contentious one, and many experts view it with a very jaundiced eye. (This includes me.)

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Ethan Siegel, Contributor

MAY 11, 2017

All scientific ideas, no matter how accepted or widespread they are, are susceptible to being overturned. For all the successes any idea may have, it only takes one experiment or observation to falsify it, invalidate it, or necessitate that it be revised. Beyond that, every scientific idea or model has a limitation to its range of validity: Newtonian mechanics breaks down close to the speed of light; General Relativity breaks down at singularities; evolution breaks down when you reach the origin of life. Even the Big Bang has its limitations, as there's only so far back we can extrapolate the hot, dense, expanding state that gave rise to what we see today. Since 1980, the leading idea for describing what came before it has been cosmic inflation, for many compelling reasons. But recently, a spate of public statements has shown a deeper controversy:

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Using a massive telescope network, scientists have data in hand that could open new frontiers in our understanding of gravity.

Westford, MassachusettsFor the monster at the Milky Way’s heart, it’s a wrap.

After completing five nights of observations, today astronomers may finally have captured the first-ever image of the famous gravitational sinkhole known as a black hole.

More precisely, the hoped-for portrait is of a mysterious region that surrounds the black hole. Called the event horizon, this is the boundary beyond which nothing, not even light, can escape the object’s gargantuan grasp.

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