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  • richardmitnick 9:26 am on May 21, 2017 Permalink | Reply
    Tags: , , , , , Gravitational waves,   

    From Manu Garcia: ” LIGO, Boxing Day” 


    Manu Garcia, a friend from IAC.

    The universe around us.
    Astronomy, everything you wanted to know about our local universe and never dared to ask.

    Author: Manu Astrologus – Update: 21/5/17
    Second detection of gravitational waves.

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    Artist illustration represents two binary black hole systems for molten GW150914 (left) and GW151226 (right). Pair of black holes are shown together in this illustration but actually detected at different times and in different parts of the sky. The images have been scaled to show the difference in the masses of black holes. In the event GW150914 , black holes were 29 and 36 times the mass of the sun, while GW151226 , the two black holes weighing between 14 and 8 solar masses. Image Credit: LIGO / A. Simonnet.


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    The two gravitational wave detectors LIGO Hanford Washington and Livingston Louisiana have captured a second robust signal of two black holes in their final orbits then coalescence, fusion <>, in a single black hole. This event, called GW151226 , was seen on 26 December at 3:38:53 (coordinated universal time, also known as Greenwich Mean Time) near the end of the first LIGO observation period ( “O1”), and it was immediately nicknamed “the boxing day event”.

    As the first detection LIGO , this event was identified few minutes after passage of the gravitational wave. Subsequently, careful studies of tools and environments around the observatories showed that observed in the two detectors signal was truly distant black holes, about 1,400 million light years away, coinciding with the same distance as the first detected signal. However, the Boxing Day event differed from the first observation of gravitational waves LIGO in some important ways.

    The gravitational wave detectors came to the two almost simultaneously, indicating that the source is somewhere in heaven ring halfway between the two detectors. Knowing our pattern detector sensitivity, we can add that was a little more likely overhead or underfoot instead of west or east. With only two detectors, however, we can not reduce it much more than that. This differs from the first detected signal LIGO ( GW150914 , from 14 September 2015), which came from the southeast, hitting the detector Louisiana before Washington.
    The two black holes merged in the event of Boxing Day were less massive (14 and 8 times the mass of our sun) than those observed in the first detection GW150914 (36 and 29 times the mass of our sun). While this made the weakest signal that GW150914 , when these lighter black holes were combined, changed its signal at higher frequencies that bring in the sensitive band LIGO before the fusion event observed in September. This allowed us to observe more orbits that the first detection-orbits about 27 in about one second (this compares with only two tenths of observation in the first detection). Combined, these two factors (smaller and observed masses orbits) were keys to allow LIGO detect a weaker signal. They also allowed us to make more accurate comparisons with General Relativity. Note: the signal again coincides with Einstein’s theory.
    Last but not least, the event Boxing Day revealed that one of the first black holes was spinning like a top – and this is a first opportunity for LIGO can state this with confidence. A rotating black hole suggests that this object has a different story – p. Maybe “he sucked” the mass of a companion star before or after a star collapsing to form a black hole, achieving rotated in the process.

    With these two detections confirmed, along with a third probable detection made in October 2015 (believed to also could be caused by a pair of coalescing black holes) we can now begin to estimate the rate of coalescence of black hole in the universe based not in theory, but in actual observations. Of course, with only a few signs, our estimate is large uncertainties, but maybe now is between 9 and 240 binary coalescence of black hole Gigaparsec cubic per year, or about one every 10 years in a volume a trillion times the volume galaxy of the Milky Way. Happily, in its first months of operation, they advanced LIGO detectors were sensitive enough to dig deep enough into space to see about an event every two months.

    Our next observation interval – Watching Round # 2, or “O2” – will begin in the fall of 2016. With improved sensitivity, we expect to see more coalescence of black holes and possibly detect gravitational waves from other sources, such as mergers of binary star neutrons. We also expect the Virgo detector will join us later in the race O2. Virgo will be enormously useful for locating sources in the sky, collapsing the ring until a patch, but also helping us to understand the sources of gravitational waves.

    LIGO releases its data to the public. This policy of open data allows others to analyze our data, ensuring that LIGO and Virgo collaborations do not lose anything in their analyzes, and hoping that others might be even more interesting events. Our data are shared in the Open LIGO Science Center. GW151226 has its own page there.

    We invite you to stroll the LIGO Laboratory website where you will find charts to help you understand the observation of Boxing Day, links to the press release and suggestions for scientific papers if you want to deepen further. There you will also find links to the website of LIGO Scientific Collaboration, and our collaboration sister, Virgo, which are essential for these scientific results.

    Credit:
    LIGO.

    See the full article here .

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  • richardmitnick 12:49 pm on May 19, 2017 Permalink | Reply
    Tags: , , , , ESA/Lisa, GEO600, Gravitational waves, ,   

    From Science Alert: “Einstein’s ‘Spooky’ Entanglement Is Guiding Next-Gen Gravitational Wave Detectors” 

    ScienceAlert

    Science Alert

    19 MAY 2017
    DAVID BLAIR

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    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    Breaking the standard quantum limit.

    The first direct detection of gravitational waves, a phenomenon predicted by Einstein’s 1915 general theory of relativity, was reported by scientists in 2016.

    Armed with this “discovery of the century”, physicists around the world have been planning new and better detectors of gravitational waves.


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    Physicist Professor Chunnong Zhao and his recent PhD students Haixing Miao and Yiqiu Ma are members of an international team that has created a particularly exciting new design for gravitational wave detectors.

    The new design is a real breakthrough because it can measure signals below a limit that was previously believed to be an insurmountable barrier. Physicists call this limit the standard quantum limit. It is set by the quantum uncertainty principle.

    Proposal for gravitational-wave detection beyond the standard quantum limit through EPR entanglement
    Yiqiu Ma, Haixing Miao, Belinda Heyun Pang, Matthew Evans, Chunnong Zhao, Jan Harms, Roman Schnabel & Yanbei Chen

    The new design, published in Nature Physics this week, shows that this may not be a barrier any longer.

    Abstract

    In continuously monitored systems the standard quantum limit is given by the trade-off between shot noise and back-action noise. In gravitational-wave detectors, such as Advanced LIGO, both contributions can be simultaneously squeezed in a broad frequency band by injecting a spectrum of squeezed vacuum states with a frequency-dependent squeeze angle. This approach requires setting up an additional long baseline, low-loss filter cavity in a vacuum system at the detector’s site. Here, we show that the need for such a filter cavity can be eliminated, by exploiting Einstein–Podolsky–Rosen (EPR)-entangled signals and idler beams. By harnessing their mutual quantum correlations and the difference in the way each beam propagates in the interferometer, we can engineer the input signal beam to have the appropriate frequency-dependent conditional squeezing once the out-going idler beam is detected. Our proposal is appropriate for all future gravitational-wave detectors for achieving sensitivities beyond the standard quantum limit.
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    Figure 1
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    figure 2
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    Figure 3
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    Figure 4
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    Figure 5

    Using this and other new approaches may allow scientists to monitor black hole collisions and ‘spacequakes‘ across the whole of the visible Universe.

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    During a spacequake, Earth’s magnetic field shakes in a way that is analogous to the shaking of the ground during an earthquake. Image credit: Evgeny Panov, Space Research Institute of Austria.

    How gravitational wave detectors work

    Gravitational waves are not vibrations travelling through space, but rather vibrations of space itself.

    They have already told us about an unexpectedly large population of black holes. We hope that further study of gravitational waves will help us to better understand our Universe.

    But the technologies of gravitational wave detectors are likely to have enormous significance beyond this aspect of science, because in themselves they are teaching us how to measure unbelievably tiny amounts of energy.

    Gravitational wave detectors use laser light to pick up tiny vibrations of space created when black holes collide. The collisions create vast gravitational explosions.

    They are the biggest explosions known in the Universe, converting mass directly into vibrations of pure space.

    It takes huge amounts of energy to make space bend and ripple.

    Our detectors – exquisitely perfect devices that use big heavy mirrors with scarily powerful lasers – must measure space stretching by a mere billionth of a billionth of a metre over the four kilometre scale of our detectors. [LIGO, above.]

    These measurements already represent the smallest amount of energy ever measured.

    But for gravitational wave astronomers this is not good enough. They need even more sensitivity to be able to hear many more predicted gravitational ‘sounds’, including the sound of the moment the Universe was created in the big bang.

    This is where the new design comes in.

    A spooky idea from Einstein

    The novel concept is founded on original work from Albert Einstein.

    In 1935 Albert Einstein and co-workers Boris Podolsky and Nathan Rosen tried to depose the theory of quantum mechanics by showing that it predicted absurd correlations between widely spaced particles.

    Einstein proved that if quantum theory was correct, then pairs of widely spaced objects could be entangled like two flies tangled up in a spider’s web. Weirdly, the entanglement did not diminish, however far apart you allowed the objects to move.

    Einstein called entanglement “spooky action at a distance”. He was sure that his discovery would do away with the theory of quantum mechanics once and for all, but this was not to be.

    Since the 1980s physicists have demonstrated time and again that quantum entanglement is real. However much he hated it, Einstein’s prediction was right and to his chagrin, quantum theory was correct. Things at a distance could be entangled.

    Today physicists have got used to the ‘spookiness’, and the theory of entanglement has been harnessed for the sending of secret codes that cannot be intercepted.

    Around the world, organisations such as Google and IBM and academic laboratories are trying to create quantum computers that depend on entanglement.

    And now Zhao and colleagues want to use the concept of entanglement to create the new gravitational wave detector’s design.

    A new way to measure gravitational waves

    The exciting aspect of the new detector design is that it is actually just a new way of operating existing detectors. It simply uses the detector twice.

    One time, photons in the detector are altered by the gravitational wave so as to pick up the waves. The second time, the detector is used to change the quantum entanglement in such a way that the noise due to quantum uncertainty is not detected.

    The only thing that is detected is the motion of the distant mirrors caused by the gravitational wave. The quantum noise from the uncertainty principle does not appear in the measurement.

    To make it work, you have to start with entangled photons that are created by a device called a quantum squeezer. This technology was pioneered for gravitational wave astronomy at Australian National University, and is now an established technique.

    Like many of the best ideas, the new idea is a very simple one, but one that took enormous insight to recognise. You inject a minuscule amount of squeezed light from a quantum squeezer, and use it twice!

    Around the world physicists are getting ready to test the new theory and find the best way of implementing it in their detectors.

    One of these is the GEO gravitational wave detector at Hannover in Germany, which has been a test bed for many of the new technologies that allowed last year’s momentous discovery of gravitational waves.

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    http://www.geo600.org GEO600 aims at the direct detection of Einstein’s gravitational waves by means of a laser interferometer.

    See the full article here .

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  • richardmitnick 6:57 am on May 16, 2017 Permalink | Reply
    Tags: , , EPR paradox, Gravitational waves, , , , Spooky action at a distance   

    From COSMOS: “Using Einstein’s ‘spooky action at a distance’ to hear ripples in spacetime” 

    Cosmos Magazine bloc

    COSMOS

    16 May 2017
    Cathal O’Connell

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    The new technique will aid in the detection of gravitational waves caused by colliding black holes. Henze / NASA

    In new work that connects two of Albert Einstein’s ideas in a way he could scarcely have imagined, physicists have proposed a way to improve gravitational wave detectors, using the weirdness of quantum physics.

    The new proposal, published in Nature Physics, could double the sensitivity of future detectors listening out for ripples in spacetime caused by catastrophic collisions across the universe.

    When the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) detected gravitational waves in late 2015 it was the first direct evidence of the gravitational waves Einstein had predicted a century before.


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    Now it another of Einstein’s predictions – one he regarded as a failure – could potentially double the sensitivity of LIGOs successors.

    The story starts with his distaste for quantum theory – or at least for the fundamental fuzziness of all things it seemed to demand.

    Einstein thought the universe would ultimately prove predictable and exact, a clockwork universe rather than one where God “plays dice”. In 1935 he teamed up with Boris Podolsky and Nathan Rosen to publish a paper they thought would be a sort of reductio ad absurdum. They hoped to disprove quantum mechanics by following it to its logical, ridiculous conclusion. Their ‘EPR paradox’ (named for their initials) described the instantaneous influence of one particle on another, what Einstein called “spooky action at a distance” because it seemed at first to be impossible.

    Yet this sally on the root of quantum physics failed, as the EPR effect turned out not to be a paradox after all. Quantum entanglement, as it’s now known, has been repeatedly proven to exist, and features in several proposed quantum technologies, including quantum computation and quantum cryptography.

    2
    Artistic rendering of the generation of an entangled pair of photons by spontaneous parametric down-conversion as a laser beam passes through a nonlinear crystal. Inspired by an image in Dance of the Photons by Anton Zeilinger. However, this depiction is from a different angle, to better show the “figure 8” pattern typical of this process, clearly shows that the pump beam continues across the entire image, and better represents that the photons are entangled.
    Date 31 March 2011
    Source Entirely self-generated using computer graphics applications.
    Author J-Wiki at English Wikipedia

    Now we can add gravity wave detection to the list.

    LIGO works by measuring the minute wobbling of mirrors as a gravitational wave stretches and squashes spacetime around them. It is insanely sensitive – able to detect wobbling down to 10,000th the width of a single proton.

    At this level of sensitivity the quantum nature of light becomes a problem. This means the instrument is limited by the inherent fuzziness of the photons bouncing between its mirrors — this quantum noise washes out weak signals.

    To get around this, physicists plan to use so-called squeezed light to dial down the level of quantum noise near the detector (while increasing it elsewhere).

    The new scheme aids this by adding two new, entangled laser beams to the mix. Because of the ‘spooky’ connection between the two entangled beams, their quantum noise is correlated – detecting one allows the prediction of the other.

    This way, the two beams can be used to probe the main LIGO beam, helping nudge it into a squeezed light state. This reduces the noise to a level that standard quantum theory would deem impossible.

    The authors of the new proposal write that it is “appropriate for all future gravitational-wave detectors for achieving sensitivities beyond the standard quantum limit”.

    Indeed, the proposal could as much as double the sensitivity of future detectors.

    Over the next 30 years, astronomers aim to improve the sensitivity of the detectors, like LIGO, by 30-fold. At that level, we’d be able to hear all black hole mergers in the observable universe.

    ESA/eLISA, the future of gravitational wave research

    However, along with improved sensitivity, the proposed system would also increase the number of photons lost in the detector. Raffaele Flaminio, a physicist at the National Astronomical Observatory of Japan, points out in a perspective piece for Nature Physics [no link], Flaminio that the team need to do more work to understand how this will affect ultimate performance.

    “But the idea of using Einstein’s most famous (mistaken) paradox to improve the sensitivity of gravitational-wave detectors, enabling new tests of his general theory of relativity, is certainly intriguing,” Flaminio writes. “Einstein’s ideas – whether wrong or right – continue to have a strong influence on physics and astronomy.”

    See the full article here .

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  • richardmitnick 8:43 am on May 2, 2017 Permalink | Reply
    Tags: , , , , , , Counterparts to Gravitational Wave Events: Very Important Needles in a Very Large Haystack, Gravitational waves   

    From astrobites: “Counterparts to Gravitational Wave Events: Very Important Needles in a Very Large Haystack” 

    Astrobites bloc

    Astrobites

    May 2, 2017
    Thankful Cromartie

    Title: Where and when: optimal scheduling of the electromagnetic follow-up of gravitational-wave events based on counterpart lightcurve models
    Authors: Om Sharan Salafia, Monica Colpi, Marica Branchesi, Eric Chassande-Mottin, Giancarlo Ghirlanda, Gabriele Ghisellini, & Susanna Vergani
    First Author’s Institutions: Universita degli Studi di Milano-Bicocca, Milano, Italy; INAF – Osservatorio Astronomico di Brera Merate, Merate, Italy; INFN – Sezione di Milano-Bicocca, Milano, Italy
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    Status: Submitted to ApJ [open access]

    The LIGO Scientific Collaboration’s historic direct detection of gravitational waves (GWs) brought with it the promise of answers to long-standing astrophysical puzzles that were unsolvable with traditional electromagnetic (EM) observations. In previous astrobites, we’ve mentioned that an observational approach that involves both the EM and GW windows into the Universe can help shed light on mysteries such as the neutron star (NS) equation of state, and can serve as a unique test of general relativity. Today’s paper highlights the biggest hinderance to EM follow-up of GW events: the detection process doesn’t localize the black hole (BH) and NS mergers well enough to inform a targeted observing campaign with radio, optical, and higher-frequency observatories. While EM counterparts to GW-producing mergers are a needle that’s likely worth searching an entire haystack for, the reality is that telescope time is precious, and everyone needs a chance to use these instruments for widely varying scientific endeavors.

    The first GW detection by LIGO, GW150914, was followed up by many observatories that agreed ahead of time to look for EM counterparts to LIGO triggers.


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA


    The authors of this study propose to improve upon the near-aimless searches in swaths of hundreds of degrees that have been necessary following the first few GW candidate events (see Figure 1). Luckily, there are two key pieces of information we have a priori (in advance): information about the source of the GW signal that can be pulled out of the LIGO data, and an understanding of the EM signal that will be emitted during significant GW-producing events

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    Figure 1: Simplified skymaps for the two likely and one candidate (LVT151012) GW detections as 3-D projections onto the Milky Way. The largest contours are 90-percent confidence intervals, while the innermost are 10-percent contours. From the LIGO Scientific Collaboration.

    What are we even looking for?

    Mergers that produce strong GW signals include BH-BH, BH-NS, and NS-NS binary inspirals. GW150914 was a BH-BH merger, which is less likely to produce a strong EM counterpart due to a lack of circumbinary material. The authors of this work therefore focus on the two most likely signals following a BH-NS or NS-NS merger. The first is a short gamma-ray burst (sGRB), which would produce an immediate (“prompt”) gamma-ray signal and a longer-lived “afterglow” in a large range of frequencies. Due to relativistic beaming, it’s rare that prompt sGRB emission is detected, as jets must be pointing in our direction to be seen. GRB afterglows are more easily caught, however. The second is “macronova” emission from material ejected during the merger, which contains heavy nuclei that decay and produce a signal in the optical and infrared shortly after coalescence. One advantage to macronova events is that they’re thought to be isotropic (observable in all directions), so they’ll be more easily detected than the beamed, single-direction sGRBs.

    (Efficiently) searching through the haystack

    LIGO’s direct GW detection method yields a map showing the probability of the merger’s location on the sky (more technically, the posterior probability density for sky position, or “skymap”). The uncertainty in source position is partly so large because many parameters gleaned from the received GW signal, like distance, inclination, and merger mass, are degenerate. In other words, many different combinations of various parameters can produce the same received signal.

    An important dimension that’s missing from the LIGO skymap is time. No information can be provided about the most intelligent time to start looking for the EM counterpart after receiving the GW signal unless the search is informed by information about the progenitor system. In order to produce a so-called “detectability map” showing not only where the merger is possibly located but also when we’re most likely to observe the resulting EM signal at a given frequency, the authors follow an (albeit simplified) procedure to inform their searches.

    The first available pieces of information are the probability that the EM event, at some frequency, will be detectable by a certain telescope, and the time evolution of the signal strength. This information is available a priori given a model of the sGRB or macronova. Then, LIGO will detect a GW signal, from which information about the binary inspiral will arise. These parameters are combined with the aforementioned progenitor information to create a map that helps inform not only where the source will most likely be, but also when various observatories should look during the EM follow-up period. Such event-based, time-dependent detection maps will be created after each GW event, allowing for a much more responsive search for EM counterparts.

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    Figure 2: The suggested radio telescope campaign for injection 28840, the LIGO signal used to exemplify a more refined observing strategy. Instead of blindly searching this entire swath of sky, observations are prioritized by signal detectability as a function of time (see color gradient for the scheduled observation times). Figure 8 in the paper.

    Using these detectability maps to schedule follow-up observations with various telescopes (and therefore at different frequencies) is complicated to say the least. The authors present a potential strategy for follow-up using a real LIGO injection (a fake signal fed into data to test their detection pipelines) of a NS-NS merger with an associated afterglow. Detectability maps are constructed and observing strategies are presented for an optical, radio, and infrared follow-up search (see Figure 2 as an example). Optimizing the search for an EM counterpart greatly increased the efficiency of follow-up searches for the chosen injection event; for example, the example radio search would have found the progenitor in 4.7 hours, whereas an unprioritized search could have taken up to 47 hours.

    Conclusions

    The process of refining an efficient method for EM follow-up is distressingly complicated. Myriad unknowns, like EM signal strength, LIGO instrumental noise, observatory availability, and progenitor visibility on the sky all present a strategic puzzle that needs to be solved in the new era of multimessenger astronomy. This work proves that improvements in efficiency are readily available, and that follow-up searches for EM counterparts to GW events will likely be more fruitful as the process is refined.

    See the full article here .

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    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
  • richardmitnick 1:45 pm on March 29, 2017 Permalink | Reply
    Tags: , , , , , Gravitational waves,   

    From aeon: “Echoes of a black hole” 

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    aeon

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    An infrared image from NASA’s Spitzer Space Telescope shows the centre of the Milky Way galaxy where the brightest white spot marks the site of a supermassive black hole
    http://www.spitzer.caltech.edu/images/1541-ssc2006-02a1-Spitzer-View-of-the-Center-of-the-Milky-Way

    3.29.17
    Sabine Hossenfelder

    A billion years ago, two dancing black holes make a final spin, merge, and – in a matter of seconds – release a cataclysmic amount of energy. Much as a falling pebble spreads waves on the surface of a still lake, the merger initiates gravitational waves in the space-time continuum. Fast-forward to planet Earth and the year 2015. After an immense journey, the gravitational waves from the black-hole merger pass through our solar system. On the morning of 14 September, they oh-so-slightly wiggle the arms of the twin Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors in Louisiana and Washington state.



    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Niayesh Afshordi at the University of Waterloo in Canada first heard of LIGO’s seminal detection over lunch in a bistro. It was late 2015 and still weeks to go until the results were officially released. But rumours were buzzing, and a colleague who had seen the unpublished paper spilled the beans. Afshordi, an astrophysicist who also works at the Perimeter Institute in Waterloo, instantly appreciated the importance of the news – both for the physics community at large, and for his own unconventional theory about the construction of the Universe.

    ‘I had an existential crisis at some point. I thought all the problems in cosmology had been solved,’ Afshordi recalled. ‘But then I came up with this idea that dark energy is made by black holes.’ Studies of distant stellar explosions and other lines of evidence show that our universe grows at an accelerating pace, but nobody knows the cause. Matter alone cannot have this effect, so cosmologists blame the expansion on a peculiar type of energy, called dark energy. Its origin and nature were, and are, a mystery.

    In 2009, Afshordi, together with his colleagues Chanda Prescod-Weinstein and Michael Balogh, put forward a theory according to which black holes seed a long-range field that mimics dark energy. The field spills out from black holes and spans through the Universe. It’s an intriguing explanation for the origin of dark energy and, by Afshordi’s calculations, the number of black holes estimated to exist should create just about the right amount of field energy to fit the observations.

    But Afshordi’s idea overthrows what physicists believed they knew about black holes. In Albert Einstein’s theory of general relativity, the event horizon of a black hole – the surface beyond which there is no escape – is insubstantial. Nothing special happens upon crossing it, just that there is no turning around later. If Afshordi is right, however, the inside of the black hole past the event horizon no longer exists. Instead, a Planck-length away from where the horizon would have been, quantum gravitational effects become large, and space-time fluctuations go wild. (The Planck length is a minuscule distance: about 10-35 metres, or 10-20 times the diameter of a proton.) It’s a complete break with relativity.

    When he heard of the LIGO results, Afshordi realised that his so-far entirely theoretical idea could be observationally tested. If event horizons are different than expected, the gravitational-wave bursts from merging black holes should be different, too. Events picked up by LIGO should have echoes, a subtle but clear signal that would indicate a departure from standard physics. Such a discovery would be a breakthrough in the long search for a quantum theory of gravity. ‘If they confirm it, I should probably book a ticket to Stockholm,’ Afshordi said, laughing.

    Quantum gravity is the missing unification of general relativity with the quantum field theories of the standard model of particle physics. If just thrown together, the two theories lead to internal contradictions, and fail to make sense. Black holes are one of the most studied examples for such a contradiction. Use quantum field theory near the horizon and you find that the black hole emits particles, slowly evaporating. Those particles carry away mass but, as Stephen Hawking demonstrated in the 1970s, they cannot carry information about what formed the black hole. And so, if the black hole evaporates entirely, all the information about what fell in has been destroyed. In quantum field theory, however, information is always preserved. Something in the mathematics, therefore, doesn’t fit correctly.

    The culprit, most physicists think, is that the calculation doesn’t take into account the quantum behaviour of space and time because the theory for this – quantum gravity – is still unknown. For decades, physicists thought that the quantum gravitational effects necessary to solve the black-hole conundrum were hidden behind the event horizon. They thought that it is only near the singularity, at the centre of the black hole, that the effects of quantum gravity become relevant. But recently, they have had to rethink.

    In 2012, a group of researchers from the University of California, Santa Barbara, found an unexpected consequence of the currently favoured idea that information somehow escapes with the radiation from a black hole. To make the idea work, large deviations from general relativity are required, not only near the singularity but also at the event horizon. Those deviations would create what the researchers dubbed a ‘black hole firewall’, a barrier of high energy just outside the horizon.

    Such a firewall (if it exists) would become noticeable only for an infalling observer, and would not emit observable signatures that could show up in our telescopes. However, the firewalls lent support to Afshordi’s earlier idea that black holes create a field that acts as dark energy. If that was so, then the near-horizon region of black holes should be very different from what general relativity predicts; a firewall that solves the black hole information-loss problem could be one effect of that deviation. Afshordi’s proposal for how to modify general relativity might therefore hold the key to resolving the tension between quantum theory and general relativity. It was an idea that wouldn’t let him go.

    When he learned of LIGO’s first detection, Afshordi began to explore whether the gravitational waves emitted from a black-hole merger could reveal intimate details about what happens near the black-hole horizon. At first it seemed too much to hope for. ‘I didn’t really think we could see quantum gravity effects in the gravitational-wave signal because we had already looked in so many places,’ Afshordi said. ‘But I changed my mind about this.’

    What made Afshordi reconsider was work by Vítor Cardoso and colleagues at the Instituto Superior Técnico in Portugal on gravitational-wave echoes from black holes. Cardoso had laid out on general grounds that a merger of two objects that are compact but do not have an event horizon would produce gravitational waves very similar to those of black holes – similar, but not identical. The key feature indicating the horizon’s absence, Cardoso argued, would be a periodic recurrence in the signal from the merger. Instead of a single peak followed by a ringdown (think a big splash on a pond, and then rapidly dissipating ripples), the gravitational waves should come as a series of fading pulses – fainter echoes of the original event. Afshordi found that the near-horizon modification described by his theory would cause exactly such echoes. Moreover, he could calculate their recurrence time as a function of the final black hole’s mass, allowing a precise prediction.

    Nobody had ever sought such a signal before, and finding it would not be easy. So far there are only two public, well-defined gravitational-wave detections from LIGO. Together with a collaborator, Afshordi analysed the LIGO data for traces of echoes. By comparing the openly available recordings to random noise, they found an echo at the calculated recurrence time. The statistical significance is not high, however. In scientific terms, it has an estimated significance of 2.9 sigma. Such a signal can be caused by pure noise with a chance of about a one-in-200. In physics, an event of such low confidence is interesting but does not amount to a discovery.

    The LIGO experiment is really just getting started, however. The most remarkable thing about the first two gravitational wave events is that the facilities were able to record them at all. The technological challenges were tremendous. Each site, both in Louisiana and in Washington state, has an interferometer with two perpendicular arms about 4 kilometres long in which a laser beam bounces back and forth between mirrors; when recombined, the beams interfere with each other. Interference of the laser’s light-waves is sensitive to deformations in the arms’ relative length as little as a thousandth the diameter of a proton. That is the level of sensitivity required to pick up gravitational effects of colliding black holes.

    A gravitational wave passing through the interferometer deforms both arms at different times, thereby skewing the interference pattern. Requiring an event to be recorded at both sites provides protection against false alarms. By design, LIGO detects gravitational waves best at wavelengths of hundreds to thousands of kilometres, the range expected for black-hole mergers. Other gravitational-wave detectors are planned to cover different parts of the spectrum, each tuned to different types of phenomena.

    Gravitational waves are an unavoidable prediction of general relativity. Einstein recognised that space-time is dynamic – it stretches, it curves, and it wiggles in response to gravitational disturbances. When it wiggles, the waves can travel freely into the far distance, carrying away energy and manifesting themselves by a periodic expansion and contraction of space in orthogonal directions. We have long had indirect evidence for gravitational waves. Because they carry away energy, they cause a small but measurable decay in the mutual orbit of binary pulsars. This effect was first observed in the 1970s, and was awarded a Nobel Prize in 1993. But until LIGO’s detection, we had no direct evidence for the existence of gravitational waves.

    LIGO’s first event – the September 2015 detection that so excited Afshordi – was remarkable, and not only because it happened just a few days after a long-planned instrumental upgrade. It stood out also because the merging black holes were so heavy, with masses estimated at 29 and 36 times the Sun’s mass. ‘A lot of people expected the black hole events to have lower masses,’ said Ofek Birnholtz, a member of the LIGO collaboration’s group on compact binary coalescence and a physicist at the Max Planck Institute in Germany. The strikingly clean signal, together with the collaboration’s openness in sharing the data, has been an inspiration for physicists in other communities who, like Afshordi, are now exploring how to use the new observations for their own work.

    On 26 December 2015, LIGO recorded a second event. The age of gravitational-wave astronomy had officially begun, after many years of slow progress and false starts. ‘Some of my PhD colleagues had left the field of gravitational-wave astronomy,’ Birnholtz said and added, laughing, ‘but are returning because suddenly it’s hot again.’ This is uncharted territory, basic research at its finest. What kind of black hole and compact stellar systems are there? Where are they within the galaxies? What do the gravitational waves reveal about their origins? If a neutron star merges with a black hole, what can be learned about matter in such extreme conditions? Do black holes behave the way that our calculations predict?

    Afshordi’s theory of black holes and dark energy is just one example of the kinds of enquiries that are now possible. A wealth of information is waiting to be explored, openly, around the world.

    A few days after Afshordi’s result appears on the open-access server arXiv.org, members of the LIGO collaboration scrutinise the analysis. It takes only a few weeks until they publish a reply, criticise the methodology, and call for different statistical tools. Birnholtz is one of the authors of that criticism.

    ‘The claim is surprising,’ said Birnholtz. ‘I have no prior as to whether or not there should be echoes. That’s physics nobody can guess at. But I do have a strong intuition, working with LIGO data, that the amplitude is probably not large enough to claim such a significance at this stage.’ Birnholtz has suggestions for how to improve the analysis, but avoids making statements about the chances of confirming the result. Alex Nielsen, another member of the LIGO collaboration and one of Birnholtz’s co-authors, reiterates the need for caution: ‘As members of the LIGO collaboration, we have to be very careful about what statements we make in public, before we have full collaboration approval. But the data is public and people can do with it what they want.’

    The LIGO collaboration has an open science centre, where data recorded for one hour around the time of confirmed gravitational events is publicly available. ‘People are welcome to use it and contact us for any questions,’ Birnholtz said. ‘If they find anything interesting, they can share it with us, and we can work on it together. This is part of the scientific experience.’

    The collaboration has several thousand members worldwide, distributed at more than a hundred institutions. They meet twice a year; the most recent meeting was in March in Pasadena, California. Some members of the collaboration are now trying to reproduce Afshordi’s analysis. Birnholtz expects the effort to take several months. ‘The result might be disappointing,’ he warned. ‘Not in that it says there are no echoes, but that we can’t say whether there are echoes.’ Gravitational-wave astronomy is still a field in its infancy, though, and much more data are on the way. The collaboration estimates that by the completion of the third observing run in 2018, LIGO is likely to have made 40 high-quality detections of black-hole mergers. Each will offer another opportunity to test Afshordi’s theory.

    Because they interact so weakly and deposit so little energy as they pass by, gravitational waves are exceedingly difficult to measure. The deformation they cause is tiny, and enormous care is necessary to extract a clean signal. The discovery threshold used by the LIGO collaboration is 5 sigma, corresponding to a chance of less than one in 3 million that the signal was coincidence, which is far above the significance level of Afshordi’s signal. The weak interaction of gravitational waves, however, is also the reason why they are excellent messengers. Unlike particles or light, they are barely affected on their way to us, carrying with them pristine information about where and how they were generated. They allow entirely new precision tests of general relativity in a regime that has never before been explored.

    If black hole echoes should be confirmed, that would almost certainly indicate a stark deviation from general relativity. Finding echoes would not uniquely confirm Afshordi’s theory that black holes seed dark energy. But some truly novel idea would be needed to explain it. ‘I don’t know of such echoes in any simulation that we have done to date,’ Birnholtz said. ‘If we were to confirm that there was an echo, that would be very interesting. We would have to look into what could produce such an echo.’

    Afshordi has research plans in case the statistical significance of his signal increases. He wants to improve his model of black-hole mergers, and run a numerical simulation to support the analytical estimate of what the echoes should look like. The next step would then be to better understand the underlying theory of space-time that could give rise to such a behaviour of the black-hole horizon. Cosmologists would also want to look much more closely at the implications of this new explanation for dark energy.

    Afshordi is aware just how speculative it is to alter general relativity so drastically. But he’s a rebel with a mission: ‘I want to encourage people to keep an open mind and not to dismiss ideas because they don’t match their preconceived notions.’ With LIGO exposing the workings of the Universe in ways never before studied, a lot of preconceived notions may soon be set aside.

    See the full article here .

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  • richardmitnick 1:31 pm on March 28, 2017 Permalink | Reply
    Tags: , , , , Gravitational waves, , SUPERRADIANCE   

    From PI via GIZMODO: “Mind-Blowing New Theory Connects Black Holes, Dark Matter, and Gravitational Waves” 

    Perimeter Institute
    Perimeter Institute

    GIZMODO

    3.28.17
    Ryan F. Mandelbaum

    The past few years have been incredible for physics discoveries. Scientists spotted the Higgs boson, a particle they’d been hunting for almost 50 years, in 2012, and gravitational waves, which were theorized 100 years ago, in 2016. This year, they’re slated to take a picture of a black hole. So, thought some theorists, why not combine all of the craziest physics ideas into one, a physics turducken? What if we, say, try to spot the dark matter radiating off of black holes through their gravitational waves?

    It’s really not that strange of an idea. Now that scientists have detected gravitational waves, ripples in spacetime spawned by the most violent physical events, they want to use their discovery to make real physics observations. They think they have a way to spot all-new particles that might make up dark matter, an unknown substance that accounts for over 80 percent of all of the gravity in the universe.

    The basic idea is that we’re trying to use black holes… the densest, most compact objects in the universe, to search for new kinds of particles,” Masha Baryakhtar, postdoctoral researcher at the Perimeter Institute for Theoretical Physics in Canada, told Gizmodo. Especially one particle: “The axion. People have been looking for it for 40 years.”

    Black holes are the universe’s sinkholes, so strong that light can’t escape their pull once it’s entered. They’ve got such powerful gravitational fields that they produce gravitational waves when they collide with each other. Dark matter might not be made from particles (specks of mass and energy), but if it was, we might observe it as axions, particles around one quintillion (a billion billion) times lighter than an electron, hanging around black holes. Now that you understand all the terms, here’s how the theory works.

    Baryakhtar and her teammates think that black holes are more than just bear traps for light, but nuclei at the center of a sort of gravitational atom. The axions would be the electrons, so to speak. If you already know about black holes, you know they have incredibly hot, high-energy discs of gas orbiting them, produced by the friction between particles accelerated by the black hole’s gravity. This theory ignores that stuff, since axions wouldn’t interact via friction.

    Keeping with the atom analogy, the axions can jump around the black hole, gaining and losing energy the same way that electrons do. But electrons interact via electromagnetism, so they let out electromagnetic waves, or light waves. Axions interact via gravity, so they let out gravitational waves. But like I said earlier, axions are tiny. Unlike a tiny atom, the black hole in these “gravity atoms” rotates, supercharging the space around it and coaxing it into producing more axions. Despite the axion’s tiny mass, this so-called superradiance process could generate 10^80 axions, the same number of atoms in the entire universe, around a single black hole. Are you still with me? Crazy spinning blob makes lots of crazy stuff.

    Craziest of all, we should be able to hear a gravitational wave hum from these axions moving around and releasing gravitational waves in our detectors, similar to the way you see spectral lines coming off of electrons in atoms in chemistry class. “You’d see this at a particular frequency which would be roughly twice the axion mass,” said Baryakhtar.

    There are giant gravitational wave detectors scattered around the world; presently there’s one called LIGO (Laser Interferometer Gravitational Wave Observatory) in Washington State, another LIGO in Louisiana, and one called Virgo in Italy that are sensitive enough to detect gravitational waves, and with upgrades, to detect axions and prove their theory right.



    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA



    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Scientists would essentially need to record data, play it back, and tune their analysis like a radio to pick up the signal at just the right frequency.

    There are other ways the team thinks it could spot this superradiance effect, by measuring the spins in sets of colliding black holes. If black holes really do produce axions, scientists would see very few quickly-spinning black holes in collisions, since the superradiance effects would slow down some of the colliding black holes and create a visible effect in the data, according to the research published this month in the journal Physical Review D. The black hole spins would have a specific pattern which we should be able to spot in the gravitational wave detector data.

    Other scientists were immediately excited about this paper. “I’m always super excited about new ways to detect my favorite pet particle, the axion! Also, SUPERRADIANCE!” Dr. Chanda Prescod-Weinstein, the University of Washington axion wrangler, told Gizmodo in an email. “It’s so cool, and I haven’t read a paper that talked about [superradiance] in years. So it was really fun to see superradiance and axions in one paper.”

    There are a few drawbacks, as there are with any theory. These theorized black hole atoms would have to produce axions of a certain mass, but that mass isn’t an ideal one for the axion to be a dark matter particle, said Prescod-Weinstein. Plus, the second detection idea, the one that looks at the spin rate of colliding black holes, might not work. “They say [in the paper] that they don’t take into account the potential influence of another black hole” in the colliding pair, Dr. Lionel London, a research associate at Cardiff University School of Physics and Astronomy specializing in gravitational wave modeling, told Gizmodo. “If this does turn out to be a significant effect and they’re not including it, this could cast doubt on their results.” But there’s hope. “There’s good reason to believe the effect of a companion [black hole] won’t be large.”

    When would we spot these kinds of events? As of now, the LIGO and Virgo gravitational wave detectors probably aren’t ready. “With the current sensitivity we’re on the edge” of detecting axions, said Baryakhtar. “But LIGO will continue improving their instruments and at design sensitivity we might be able to see as many as 1000s of these axion signals coming in,” she said. Thousands of hums from these black hole-atoms.

    So, if you’ve gotten all the way to this point of the story and still don’t understand what’s going on, a recap: We’ve got these gravitational wave detectors that cost hundreds of millions of dollars each, that are good at spotting really crazy things going on in the universe. Theorists have come up with an interesting way to use them to solve one of the most important interstellar mysteries: What the heck is dark matter? As with most new ideas in theoretical physics, this is something cool to think about and isn’t ready for the big time… yet.

    “I think that timescale is always a concern, but we’re just getting started with LIGO discoveries,” said Prescod-Weinstein. “So who knows what’s around the corner over the next 10 years.”

    See the full article here .

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    About Perimeter

    Perimeter Institute is the world’s largest research hub devoted to theoretical physics. The independent Institute was founded in 1999 to foster breakthroughs in the fundamental understanding of our universe, from the smallest particles to the entire cosmos. Research at Perimeter is motivated by the understanding that fundamental science advances human knowledge and catalyzes innovation, and that today’s theoretical physics is tomorrow’s technology. Located in the Region of Waterloo, the not-for-profit Institute is a unique public-private endeavour, including the Governments of Ontario and Canada, that enables cutting-edge research, trains the next generation of scientific pioneers, and shares the power of physics through award-winning educational outreach and public engagement.

     
  • richardmitnick 6:12 pm on March 7, 2017 Permalink | Reply
    Tags: , , , Gravitational waves, ,   

    From APS: “Gravitational Waves: Hints, Allegations, and Things Left Unsaid” 

    AmericanPhysicalSociety

    American Physical Society

    APS April Meeting 2017

    If the APS April Meeting 2016 was a champagne-soaked celebration for gravitational wave scientists, the 2017 meeting was more like spring training — there was lots of potential, but the real action is yet to come.



    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    The Laser Interferometer Gravitational-Wave Observatory, or LIGO, launched the era of gravitational wave astronomy in February 2016 with the announcement of a collision between two black holes observed in September 2015. “I’m contractually obligated to show the slide [of the original detection] at any LIGO talk for at least another year,” joked Jocelyn Read, a physicist at California State University, Fullerton, during her presentation at this year’s meeting.

    The scientific collaboration that operates the two LIGO detectors netted a second merger between slightly smaller black holes on December 26, 2015. (A third “trigger” showed up in LIGO data on October 12, 2015, but ultimately did not meet the stringent “five-sigma” statistical significance standard that physicists generally insist on.)

    The detectors then went offline in January 2016 for repairs and upgrades. The second observing run began on November 30, but due to weather-related shutdowns and other logistical hurdles, the two detectors had operated simultaneously on only 12 days as of this year’s meeting, which limited the experiment’s statistical power. Collaboration members said they had no new detections to announce.

    Instead, scientists focused on sharpening theoretical estimates of how often various events occur. In particular, they are eager to see collisions involving neutron stars, which lack sufficient mass to collapse all the way to a black hole. Neutron star collisions are thought to be plentiful, but would emit weaker gravitational waves than do mergers of more massive black holes, so the volume of space the LIGO detectors can scan for such events is smaller.

    Even with recent upgrades, failure to detect a neutron star merger during the current observing run would not rule out existing models, said Read. But she added that with future improvements and the long-anticipated addition of Virgo, a LIGO-like detector based in Cascina, Italy, neutron stars should soon come out of hiding.



    VIRGO Gravitational Wave interferometer, near Pisa, Italy [Not yet operational]

    “We’re expecting that with a little more volume and a little more time, we’re going to be starting to make some astrophysically interesting statements.”

    LIGO scientists are also looking for signals from individual pulsars — rapidly rotating neutron stars that are observed on earth as pulses of radio waves. A bump on a pulsar’s surface should produce gravitational waves, but so far, no waves with the right shape have been picked up. This absence puts a limit on the size of any irregularities and on the emission power of gravitational waves from nearby pulsars such as the Crab and Vela pulsars, said Michael Landry, head of the Hanford LIGO observatory, and could soon start putting limits on more distant ones.

    Presenters dropped a few hints of possible excitement to come. LIGO data taken through the end of January produced two short signals that were unusual enough to exceed the experiment’s “false alarm” threshold — signals with shapes and strengths expected to show up once a month or less by chance alone. Both LIGO collaboration members and astronomers at conventional telescopes are investigating the data to determine whether they represent real events.

    For now, potential events will continue to be scrutinized by collaboration members, and released to the public via announcements coming months after initial detection. But LIGO leaders expect to shorten the lag time as detections become more frequent, perhaps eventually putting out monthly updates. “We hope to make it quicker,” said LIGO collaboration spokesperson Gabriela González, a physicist at Louisiana State University in Baton Rouge.

    LIGO is not the only means by which scientists are searching for gravitational waves. Some scientists are using powerful radio telescopes to track signals emanating from dozens of extremely fast-rotating pulsars. A specific pattern of correlations between tiny hiccups in the arrival times of these pulses would be a signature of long-wavelength gravitational waves expected from mergers of distant supermassive black holes.

    Teams in the U.S., Europe, and Australia have monitored pulsars for more than a decade, so far without positive results. But in an invited talk, Laura Sampson of Northwestern University in Evanston, Illinois, coyly announced “hints of some interesting signals.” With 11 years of timing data from 18 pulsars tracked by the Green Bank Telescope in West Virginia and the Arecibo Telescope in Puerto Rico, Sampson and other scientists affiliated with a collaboration called NANOGrav have eked out a result with a statistical significance of around 1.5 to 2 sigma.



    GBO radio telescope, Green Bank, West Virginia, USA


    NAIC/Arecibo Observatory, Puerto Rico, USA

    Data from the Green Bank Telescope in West Virginia and Arecibo Telescope in Puerto Rico help researchers use pulsars to study gravitational waves.

    “It’s the first hint we’ve ever had that there might be a signal in the data,” Sampson said. “Everything we’ve done before was straight-up limits.”

    As NANOGrav continues to gather data, their signal could grow toward the 5-sigma gold standard, or it could vanish. Sampson and her colleagues hope to have an answer in the next year or two. “This is of course very exciting news,” said Gonzalez.

    See the full article here .

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    American Physical Society
    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries.

     
  • richardmitnick 12:15 pm on March 5, 2017 Permalink | Reply
    Tags: , , , , Gravitational waves,   

    From Nautilus: “Gravity’s Kiss – The third ripple. 

    Nautilus

    Nautilus

    3.5.17
    Harry Collins

    Gravity’s Kiss by Harry Collins, is published by the MIT Press.

    LIGO bloc new
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    VIRGO Collaboration bloc
    VIRGO Gravitational Wave interferometer, near Pisa, Italy
    VIRGO Gravitational Wave interferometer, near Pisa, Italy [not yet operational]

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project
    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib
    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    Gravitational waves are finding their way to the general public. There is massive television news coverage with never a doubt expressed; gravitational waves have simply “been detected”—exciting but no more dubious than, say, the moon landing. What is happening is that gravitational waves are being “domesticated” in the same way as black holes or the Higgs have been domesticated. Everyone knows what a black hole is—it is a feature of everyone’s day-to-day life embedded in a “semantic net” that includes “the cosmos,” “the big bang,” “Stephen Hawking,” “brilliant scientists,” “Einstein,” “space,” “alternative universes,” “time travel,” “worm-holes,” “astronomy,” “rockets,” and “being sucked into things”—and this is in spite of the fact that, before The Event, no black hole had been observed except by inference. As for the Higgs, everyone knows that it was found by the huge and brilliant team at CERN, but, familiar as it is, no one knows what it is. I know it is the last piece in the jigsaw puzzle of the particle “zoo” known as the standard model, but what I have is “beer-mat knowledge,” good for answering questions in Trivial Pursuit but that’s about it. On the other hand, the fact that we can imagine encountering questions about black holes and the Higgs while playing Trivial Pursuit is one of the things that makes them real: all this familiar knowledge makes stuff real. The moon landing, note, is pretty real for everyone but, just as in the case of what is building in respect of The Event, there are conspiracy theories about that too; and, just as in this case, you have to stray from the mainstream to find them.

    On Friday I gather a good selection of the United Kingdom print newspapers; they are big contributors to the domestication process. The Guardian is a broadsheet for the left-liberal middle classes and its news section is 38 pages long. It gives the story the lead and whole of page 11. It had also given it the whole of page 3 on Wednesday, building the story on the rumors. On Saturday, The Guardian’s regular political cartoon features the Syrian peace talks represented as some kind of funny-looking celestial object with the caption: “Not gravitational waving but gravitational drowning.” Thus do gravitational waves spread into the ordinary language.

    1
    EXTRA! EXTRA!Newspaper front pages from around the world.
    Courtesy of LIGO

    The Independent has a similar readership to The Guardian but has a smaller tabloid format with 72 pages. It gives the story the entire page 1 and pages 6–8; it opines that this is “one of the greatest achievements in human history.”

    The Telegraph is another broadsheet, with 38 pages in its news section. It is a right-wing, patriotic paper for the educated. It makes gravitational waves the second story on page 1, leading with:

    A British scientist who was pivotal in the project to detect gravitational waves could not celebrate the momentous discovery with colleagues because he is suffering from dementia.

    This, of course, is Ron Drever. The paper also gives up pages 10 and 11 to the story.

    Martin Rees, the Astronomer Royal, writes columns in The Independent and the Telegraph. He opines that this is of similar importance to the discovery of the Higgs; most other commentators say it is much more important than the Higgs, but Rees has long been said by gravitational wave physicists to be less than enthusiastic about the enterprise.

    The Daily Mail is a “little Englander” tabloid with 92 pages serving those with strong right-wing opinions. It gives the story half of page 10, mistakenly claiming that Einstein predicted that colliding stars would generate gravitational waves that could be detected on Earth, whereas he actually thought they would remain completely undetectable.

    The Mirror is a left-leaning tabloid with 80 pages. It gives the story most of page 21 but says that LIGO was invented by Thorne and Weiss, missing out on Drever.

    The Sun is a tabloid with 60 pages that began its life by publishing photographs of topless models on the notorious “page 3” (now dropped). The only science I could find was on the bottom third of page 15, head-lined: “Top Prof Dies in Rubber Suit with Dog Lead Round Neck.” The “Top Prof” does not seem to have been one of the gravitational wave team.

    The Guardian website of February 12 includes a hilarious cartoon—one of a series called “First Dog on the Moon,” which anticipates one of my major sociological theses. The fourth panel of the cartoon opines:

    Obviously we can’t see these waves—the only way we know they are real is by using another extremely sensitive device which detects scientists having feelings of excitement.

    The excitement evoked in scientists by a gravitational wave is calibrated using the marginally smaller effect of a cheese salad sandwich as a standard candle.

    Later I will discover that my major thesis about social construction, which turns on pointing out that no gravitational waves were seen but merely a few numbers that were interpreted as gravitational waves, has been thoroughly anticipated (albeit on a strange, flat-earther YouTube channel that appears to treat conspiracy theories as an art form). It claims scientists have not seen gravitational waves, nor has their machine seen gravitational waves, but that the machine produces lots of glitchy noises out of which they have picked one and interpreted it as a gravitational wave.

    A member of the LIGO team has put together a collection of newspaper front pages from around the world. And, as though to put an indelible stamp on the soon to be taken for granted nature of this exotic phenomenon, in the United States the discovery is presented on Saturday Night Live and The Tonight Show, and, on Saturday, February 13, the humorous U.S. radio show A Prairie Home Companion devotes about five minutes to gravitational waves. Gravitational waves have arrived!

    The physicists continue to do my job for me by gathering more indications of the domestication of gravitational waves. On February 16, a French (presumably humorous) website normalizes the waves in contemporary fashion by calling for a ban on them and the distribution of protective helmets. This is a Google translation from the French with my minor edits:

    “For a Moratorium on Gravitational Waves

    Bringing together hundreds of independent researchers, the “Collective for a moratorium on gravitational waves” (COMOG) sent us this platform. We publish it verbatim in our columns:

    In recent days, highlighting the “gravitational waves” continues to make the press headlines. Everyone welcomes this alleged “scientific breakthrough,” which was published in the Physical Review Letters, a journal under orders of the nuclear lobby.

    Now, our collective, consisting of independent researchers who wish to remain anonymous for their own reasons, is concerned about the apparent toxicity of gravitational waves.

    To date, there is in fact no serious study establishing the actual safety of these waves. That is why we propose an action plan of four points.

    1. We recall, first, that the oscillations of the curvature of space-time can present health risks found, especially on the neurological system of employees too long exposed to the gravitational waves. It is appropriate in this case to call for the government to strictly enforce the Labour Code, to limit the time of exposure to gravitational waves, and equip the wage earners with protective helmets.

    2. To these health risks are added, as often environmental, of deleterious economic effects. The curvature of space-time is likely to cause untoward inconvenience, especially in the field of transport and travel. An example: If space-time is curved in the wrong direction when one performs a trip from Paris to Bordeaux, the journey can last more than 25 hours, according to our estimates. Gravitational waves expose the French economy to serious danger that cannot be underestimated.

    3. It appears that the production of gravitational waves calls for masses of matter and energy that are absolutely astounding: black holes, neutron stars, washing machines, etc. We ask that the environmental and climate impact of gravitational waves be measured in France by an independent body and a carbon footprint be determined as quickly as possible.

    4. As a result, we ask Ségolène Royal, Minister of Environment, Energy and the Sea, responsible for international relations on the climate, to apply the constitutional principle of precaution, and to take by decree related measures that are defined and recommended in principle 15 of the Rio Declaration. It seems to us urgent that France decide on a moratorium on gravitational waves.

    If the government does not abide by these basic precautions, peaceful COMOG teams will be forced to resort to direct action. Within six months, we will proceed to the systematic dismantling of gravitational wave antennas. Our teams of volunteer harvesters shall uproot the plants of space-time curvatures. Finally, we will not hesitate to leave Paris to set up a zone to defend Proxima Centauri, even against the advice of the prefect.

    We call upon our fellow citizens to join our fight. Gravitational waves, no thank you!”

    On February 18, the Huddersfield Daily Examiner (Huddersfield is a town in North England with a football club—“Huddersfield Town”—all about as provincially English as can be) carries a story about the “Huddersfield Town Supporters Association” (HTSA). It includes:

    Our HTSA column last week touched upon the subject of regional supporters groups and their recent cosmic rise in popularity. The Laser Interferometer Gravitational-Wave Observatory (LIGO) can probably demonstrate whether this is due to colliding Black Holes over Bexleyheath.

    And Barack Obama had tweeted on February 11:

    Einstein was right! Congrats to @NSF and @LIGO on detecting gravitational waves—a huge breakthrough in how we understand the universe.

    At the forthcoming American Physical Society (APS) meeting, Dave Reitze, the director of LIGO, will present a slide showing a woman wearing a dress patterned with the waveform, an Australian competition swimmer with the waveform on his swim-cap, and a New York advertisement for apartments.

    2
    Fashionably wavy. More domestication of gravitational waves. No image credits.

    I attend two meetings in March: a general relativity 100th anniversary meeting at Caltech and the LIGO-Virgo collaboration meeting in Pasadena. Of course, the cat is now out of the bag so a big topic at the Caltech meeting is The Event. I follow Barry Barish onto the platform; he describes the technicalities and I talk about the way small science and big science had combined to create this possibility, with Barish bringing about the necessary transformation, and I talk about what it meant for me as a sociologist to be confronted by such a sudden and certain result. At neither meeting is there any criticism but the LVC is selling huge numbers of T-shirts and polo shirts with the waveform of The Event printed or embroidered on them: The waveform is becoming an icon! Many more such garments will be sold at the April APS meeting.

    At the March meeting of the APS—a much larger meeting than the April meeting I am going to attend—a group of physicists who have nothing to do with LIGO or gravitational waves performed a song based on the Neil Diamond/Monkees’ “I’m a Believer.” The lyrics are as follows:

    “I’m a LIGO Believer.” Lyrics: Marian McKenzie. Tune: “I’m a Believer,” by Neil Diamond (courtesy Marian McKenzie).

    I thought waves of gravity were fairy tales—fine for dilettantes, but not for me.
    What’s the use of searching?
    Noise is all you’ll find.
    I don’t want to clutter up my mind—

    [Chorus:] Then I saw the graph—Now I’m a believer!
    You can laugh, and hold me in scorn.
    I’m convinced, oooh, I’m a believer
    In Weiss, Reitze, Drever, Gonzalez, and Thorne!

    Einstein spoke of grav wave propagation.
    Weber tried to find them on the moon.
    BICEP2 announced them,
    Then said “Never mind.”
    —Do you wonder I was disinclined?

    [Sing chorus] [instrumental interlude] and repeat”

    The whole song can be seen and heard on YouTube.

    3
    surfing the googleEnormous spike in interest in gravitational waves around February 11. No image credit.

    What about social media? Google Trends (see chart above) shows the huge spike in interest in gravitational waves around the February 11 press conferences by tracking hits on Google. Unfortunately, we have only the normalized trend, the scale having a maximum of 100, not absolute numbers.

    4
    Breaking the internet. The enormous spike in interest in gravitational waves compared to hits for Kim Kardashian.

    Gravitational waves are not, however, about to take over the popular imagination. The chart above shows the same spike in comparison to Google hits for Kim Kardashian, the reality TV star. Gravitational waves’ enormous spike is a mere 2 percent as high as Kardashian’s peak performance and only about 5 percent as high as her average day-to-day score. Aside from the spike, gravitational waves score zero when compared to Kardashian’s average.

    See the full article here .

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    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

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  • richardmitnick 4:49 pm on February 12, 2017 Permalink | Reply
    Tags: , Gravitational waves, oscillon, U Basel   

    From U Basel: “Ancient Signals From the Early Universe” 

    u-basel-bloc

    U Basel

    February 12, 2017
    No writer credit

    2
    The animation shows a computer simulation of an oscillon, a strong localized fluctuation of the inflaton field of the early universe. According to the calculations of Prof. Stefan Antusch and his team, oscillons produced a characteristic peak in the otherwise broad spectrum of gravitational waves. © Department of Physics, University of Basel

    For the first time, theoretical physicists from the University of Basel in Switzerland have calculated the signal of specific gravitational wave sources that emerged fractions of a second after the Big Bang. The source of the signal is a long-lost cosmological phenomenon called “oscillon”. The journal Physical Review Letters has published the results.

    Although Albert Einstein had already predicted the existence of gravitational waves, their existence was not actually proven until fall 2015, when highly sensitive detectors received the waves formed during the merging of two black holes. Gravitational waves are different from all other known waves. As they travel through the universe, they shrink and stretch the space-time continuum; in other words, they distort the geometry of space itself. Although all accelerating masses emit gravitational waves, these can only be measured when the mass is extremely large, as is the case with black holes or supernovas.

    Gravitational waves transport information from the Big Bang

    However, gravitational waves not only provide information on major astrophysical events of this kind but also offer an insight into the formation of the universe itself. In order to learn more about this stage of the universe, Prof. Stefan Antusch and his team from the Department of Physics at the University of Basel are conducting research into what is known as the stochastic background of gravitational waves. This background consists of gravitational waves from a large number of sources that overlap with one another, together yielding a broad spectrum of frequencies. The Basel-based physicists calculate predicted frequency ranges and intensities for the waves, which can then be tested in experiments.

    A highly compressed universe

    Shortly after the Big Bang, the universe we see today was still very small, dense, and hot. “Picture something about the size of a football,” Antusch explains. The whole universe was compressed into this very small space, and it was extremely turbulent. Modern cosmology assumes that at that time the universe was dominated by a particle known as the inflaton and its associated field.

    Oscillons generate a powerful signal

    The inflaton underwent intensive fluctuations, which had special properties. They formed clumps, for example, causing them to oscillate in localized regions of space. These regions are referred to as oscillons and can be imagined as standing waves. “Although the oscillons have long since ceased to exist, the gravitational waves they emitted are omnipresent – and we can use them to look further into the past than ever before,” says Antusch.

    Using numerical simulations, the theoretical physicist and his team were able to calculate the shape of the oscillon’s signal, which was emitted just fractions of a second after the Big Bang. It appears as a pronounced peak in the otherwise rather broad spectrum of gravitational waves. “We would not have thought before our calculations that oscillons could produce such a strong signal at a specific frequency,” Antusch explains. Now, in a second step, experimental physicists must actually prove the signal’s existence using detectors.

    Original article

    Stefan Antusch, Francesco Cefalà, and Stefano Orani
    Gravitational Waves from Oscillons after Inflation
    Physical Review Letters (2017), doi: 10.1103/PhysRevLett.118.011303

    See the full article here .

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    Purposes

    The University of Basel fosters the development of critically thinking and tolerant individuals who are capable of taking initiative and taking on responsibility. It is the aim of the University to enable these individuals to deepen their knowledge and field-specific academic training and further education.

    Through research and teaching, the University imparts the insights past down over the ages in addition to producing new knowledge. It is guided by the principle of meaningfulness and purpose rather than feasibility.

    The University is aware of the duties arising from knowledge, fulfilling these duties through critical reflection and the services it provides. It takes its own position concerning problems facing society.

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  • richardmitnick 11:17 am on February 12, 2017 Permalink | Reply
    Tags: , , Gravitational waves,   

    From Science Alert: “Surprise! LIGO Can Also Make Gravitational Waves” 

    ScienceAlert

    Science Alert

    2

    FUTURISM

    11 FEB 2017
    DOM GALEON

    1
    NASA

    We can produce gravitational waves now.

    It’s been almost a year now since the Laser Interferometer Gravitational-Wave Observatory (LIGO) announced the greatest scientific discovery of 2016.

    LIGO bloc new
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Though the first gravitational waves were actually detected in September 2015, it was only after additional detections were made in June 2016 that LIGO scientists finally confirmed that the elusive waves exist, solidifying Albert Einstein’s major prediction in his theory of relativity.

    Now, the most sensitive detector of spacetime ripples in the world turns out to also be the best producer of gravitational waves.

    “When we optimise LIGO for detection, we also optimise it for emission [of gravitational waves],” said physicist Belinda Pang from the California Institute of Technology (Caltech) in Pasadena according to a report in Science.

    Pang was speaking at a meeting of the American Physical Society last week, representing her team of physicists.

    Gravitational waves are ripples that are produced when massive objects warp spacetime.

    They essentially stretch out space, and according to Einstein, they can be produced by certain swirling configurations of mass. Using uber-sensitive twin detectors in Hanford, Washington, and Livingston, Louisiana, LIGO is able to detect this stretching of space.

    Once they realised they could detect gravitational waves, the physicists posited that the sensitivity of their detectors would enable them to efficiently generate these ripples, too.

    “The fundamental thing about a detector is that it couples to gravitational waves,” said Fan Zhang, a physicist at Beijing Normal University.

    “When you have coupling, it’s going to go both ways.”

    The LIGO team tested their idea using a quantum mathematical model and found that they were right: their detectors did generate tiny, optimally efficient spacetime ripples.

    Quantum mechanics says that small objects, such as electrons, can be in two places at once, and some physicists think that it’s possible to coax macroscopic objects into a similar state of quantum motion.

    According to Pang, LIGO and these waves could be just the things to make it happen.

    Though that delicate state couldn’t be sustained for very long periods, any amount of time could give us added insight into quantum mechanics.

    We could measure how long it takes for decoherence to occur and see what role gravity might play in the existence of quantum states between macroscopic objects.

    “It’s an interesting idea, but experimentally it’s very challenging,” explained Caltech physicist Yiqui Ma, one of Pang’s colleagues.

    “It’s unbelievably difficult, but if you want to do it, what we’re saying is that LIGO is the best place to do it.”

    Any added insight into quantum activity could not only help us build better quantum computers, it could completely revolutionise our understanding of the physical universe.

    LIGO is already in the process of receiving upgrades that will help it detect even fainter gravitational waves, and eventually, the plan is to build the Evolved Laser Interferometer Space Antenna (eLISA), a gravitational wave observatory in space.

    ESA/LISA Pathfinder
    ESA/LISA Pathfinder

    ESA/eLISA
    ESA/eLISA

    Within the next decade, not only could LIGO be regularly detecting gravitational waves, it could also be finding ever more advanced ways to create them and furthering our understanding of the quantum world in unimaginable ways.

    See the full article here .

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