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Astrophysicists discover exotic merger of black holes
Gravitational wave researchers observe black holes of different sizes colliding for the first time.
21 April, 2020
Simulation of two black holes of different size orbiting each other, while emitting gravitational waves. Blue colors are weaker gravitational radiation and red is stronger.
- Gravitational wave researchers at LIGO and Virgo observatories spot black holes of different sizes colliding.
- The finding is unusual because previous black hole mergers involved partners of similar size.
- The new information re-confirms Einstein's theory of relativity.
<p>Gravitational wave researchers discovered a very unusual merger of black holes 2.4 billion light-years away. They spotted a collision where one black hole was almost four times larger than another, expanding our understanding of such space cataclysms with help from Einstein (and even Elvis). </p><p><span style="background-color: initial;">All mergers detected previously involved partners of comparable sizes. The event detected on April 12th, 2019 </span><span style="background-color: initial;">was called "exceptional" by <strong>Maya Fishbach</strong>, an astrophysicist at the University of Chicago in Illinois. What she and her colleagues found proves that very unevenly matched black hole pairs exist. </span><span style="background-color: initial;">"This is the first event in which we can confidently say the mass-ratio is not one," she stated during an <a href="https://aps-april.onlineeventpro.freeman.com/" target="_blank">online meeting</a> of the </span><span style="background-color: initial;">American Physical Society.</span></p>
<p>The research was carried out in collaboration between the <a href="https://www.ligo.caltech.edu/" target="_blank">Laser Interferometer Gravitational-Wave Observatory (LIGO) </a>— twin detectors in Washington and Louisiana — as well as the <a href="http://www.virgo-gw.eu/" target="_blank">Virgo observatory</a> near Pisa, Italy. They both detected the merger. One of the black holes observed was <strong>30 times</strong> more massive than the sun and was spinning, said the scientists, while the other had a mass about <strong>eight times</strong> that of the sun.</p><p>In an amusing note, the scientists say that the very different masses created gravitational waves at multiple frequencies, which were actually in harmony with an Elvis Presley song. This cosmic music also confirms yet again Einstein's theory of general relativity.</p><p>Normally, two spiraling black holes of the same size would emit a single frequency, which would be double the rate at which they are orbiting one another, <a href="https://www.sciencemag.org/news/2020/04/gravitational-waves-reveal-unprecedented-collision-heavy-and-light-black-holes" target="_blank">explains</a> Science Magazine. In this case, as predicted by Einstein, the very different masses, also produce <em>overtones</em> - weaker waves at higher frequencies. And if you were to transpose these frequencies to piano notes and intervals, you would get the beginning of Presley's classic <a href="https://www.youtube.com/watch?v=GSaxhqJG1Mw" target="_blank">"I Can't Help Falling in Love with You."</a></p>
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<p>The scientists hope that this uniqueness of the detected event could help provide more information about how black holes form. Of special interest is how the variation in mass could have arisen. Under one scenario, the pair could be the result of two massive stars who were orbiting each other, collapsing into black holes. Under another theory, the black holes could have formed independently and found each other in dense star clusters.</p><p>You can read more of the new findings on the <a href="https://arxiv.org/abs/2004.08342" target="_blank">arXiv preprint server.</a></p>
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Astrophysicists discover why black holes and neutron stars shine bright
Researchers find what causes the glow coming from the densest objects in our universe.
29 November, 2019
Credit: NASA, ESA, J. Hester (Arizona State University)
- Columbia University astrophysicists discovered the cause of the unusual glow coming from regions of space with black holes and neutron stars.
- The researchers ran some of the largest computer simulations ever to reach their conclusions.
- They found that turbulence and reconnection of super-strong magnetic fields are responsible for the light.
<p><br></p></div>
<p>Demonstrating again that space is a limitless reservoir of scientific wonders, a new study discovered why areas hosting black holes and neutron stars emit strange bright glows. Astrophysicists found that <strong>turbulence</strong> and <strong>reconnection of super-strong magnetic fields</strong> are behind the cosmic mystery.</p><p>The cause of the phenomenon, which illuminates these super-dense parts of space, has been attributed previously to high-energy electromagnetic radiation. Scientists speculated that it's created by electrons moving at just about the speed of light. The new study from researchers at Columbia University explained why these particles accelerate.</p><p>Astrophysicists <a href="https://lucacomisso.com/about/" target="_blank">Luca Comisso</a> and <a href="http://user.astro.columbia.edu/~lsironi/Site/Home.html" target="_blank">Lorenzo Sironi</a> carried out the research by running some of the largest super-computer simulations ever conducted in this area. They managed to calculate the trajectories of hundreds of billions of charged particles.</p>
<p>Comiso, a postdoctoral research scientist at Columbia, explained their conclusion:</p><p style="margin-left: 20px;">"Turbulence and magnetic reconnection—a process in which magnetic field lines tear and rapidly reconnect—conspire together to accelerate particles, boosting them to velocities that approach the speed of light," said Comisso in a <a href="https://news.columbia.edu/news/black-holes-neutron-stars" target="_blank">press release</a>. </p><p>As Comiso further described, the space region that is home to black holes and neutron stars is also full of a super-hot gas of charged particles. Their chaotic motion affects magnetic field lines and results in "vigorous magnetic reconnection". This, in turn, creates an electric field which accelerates particles to energies that are "much higher than in the most powerful accelerators on Earth, like the Large Hadron Collider at CERN," added Comisso.</p>
Amazing astronomy: How neutron stars create ripples in space-time
<div class="rm-shortcode" data-media_id="skGLOb3j" data-player_id="FvQKszTI" data-rm-shortcode-id="4181b5782ae4c412ce8a339ea70571ff"> <div id="botr_skGLOb3j_FvQKszTI_div" class="jwplayer-media" data-jwplayer-video-src="https://content.jwplatform.com/players/skGLOb3j-FvQKszTI.js"> <img src="https://cdn.jwplayer.com/thumbs/skGLOb3j-1920.jpg" class="jwplayer-media-preview" /> </div> <script src="https://content.jwplatform.com/players/skGLOb3j-FvQKszTI.js"></script> </div><p>Interestingly, the simulations showed that the particles gathered most of their energy through the process of random bouncing at super-high speeds.</p><p style="margin-left: 20px;">"This is indeed the radiation emitted around black holes and neutron stars that make them shine, a phenomenon we can observe on Earth," said Sironi, the study's principal investigator and an assistant professor of astronomy at Columbia.</p><p>Next, the scientists plan to confirm their findings by comparing them to the electromagnetic spectrum from the Crab Nebula, a bright remnant of a supernova. </p><p>You can check out the study published in the December issue of <a href="https://iopscience.iop.org/article/10.3847/1538-4357/ab4c33" target="_blank"><em>The Astrophysical Journal</em></a><em>.</em></p>
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjExMzI3My9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyMDA3MTU2Mn0.ESRk0s8UeKMmTIIRY_iBz6LSM7pNLKbhg1egqx_o79A/img.jpg?width=980" id="ab685" class="rm-shortcode" data-rm-shortcode-id="b47a1d1e3159133ec95b8a6225669f77" data-rm-shortcode-name="rebelmouse-image" />
A massive super-computer simulation demonstrates the strong particle density fluctuations that happen in the extreme turbulent environments home to black holes and neutron stars. The dark blue regions are low particle density regions, and the yellow regions are over-dense regions. Particles are accelerated to extremely high speeds from interacting with turbulence fluctuations.
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Black hole death: How extreme tidal forces turn humans into spaghetti
Getting to close to a black hole is a nightmare waiting to happen.
28 January, 2019
- Like ocean tides caused by gravity, a nearby black hole would create a 'tide' inside your body, which is mostly water.
- As your body drew nearer to the black hole, your head would be stretched away from your feet.
- Scientists call this streching "spaghettification", from the word of spaghetti.
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Rotating black holes may serve as gentle portals for hyperspace travel
Feel like traveling to another dimension? Better choose your black hole wisely.
27 January, 2019
One of the most cherished science fiction scenarios is using a black hole as a portal to another dimension or time or universe. That fantasy may be closer to reality than previously imagined.
<p>Black holes are perhaps the most mysterious objects in the universe. They are the consequence of gravity crushing a dying star without limit, leading to the formation of a true singularity – which happens when an entire star gets compressed down to a single point yielding an object with infinite density. This dense and hot singularity punches a hole in the fabric of spacetime itself, possibly opening up an opportunity for hyperspace travel. That is, a short cut through spacetime allowing for travel over cosmic scale distances in a short period. </p><p>Researchers previously thought that any spacecraft attempting to use a black hole as a portal of this type would have to reckon with nature at its worst. The hot and dense singularity would cause the spacecraft to endure a sequence of increasingly uncomfortable tidal stretching and squeezing before being completely vaporized.</p><h2>Flying through a black hole</h2><p><a href="http://gravity.phy.umassd.edu/">My team</a> at the University of Massachusetts Dartmouth and a colleague at Georgia Gwinnett College have shown that all black holes are not created equal. If the black hole like Sagittarius A*, located at the center of our own galaxy, is large and rotating, then the outlook for a spacecraft changes dramatically. That's because the singularity that a spacecraft would have to contend with is very gentle and could allow for a very peaceful passage. </p><p>The reason that this is possible is that the relevant singularity inside a rotating black hole is technically “weak," and thus does not damage objects that interact with it. At first, this fact may seem counter intuitive. But one can think of it as analogous to the common experience of quickly passing one's finger through a candle's near 2,000-degree flame, without getting burned. </p><p>My colleague <a href="https://scholar.google.com/citations?user=Zsn-SygAAAAJ&hl=en" target="_blank">Lior Burko</a> and <a href="https://scholar.google.com/citations?user=382Ttr0AAAAJ&hl=en">I</a> have been investigating the physics of black holes for over two decades. In 2016, my Ph.D. student, Caroline Mallary, inspired by Christopher Nolan's blockbuster film <a href="https://www.imdb.com/title/tt0816692/">“Interstellar,"</a> set out to test if Cooper (Matthew McConaughey's character), could survive his fall deep into Gargantua – a fictional, supermassive, rapidly rotating black hole some 100 million times the mass of our sun. “Interstellar" was based on a book written by Nobel Prize-winning astrophysicist <a href="https://www.nobelprize.org/prizes/physics/2017/thorne/facts/">Kip Thorne</a> and Gargantua's physical properties are central to the plot of this Hollywood movie.<br></p><p>Building on work done by physicist <a href="https://phys.technion.ac.il/en/people/faculty/person/44" target="_blank">Amos Ori</a> two decades prior, and armed with her strong computational skills, <a href="https://doi.org/10.1103/PhysRevD.98.104024" target="_blank">Mallary built a computer model</a> that would capture most of the essential physical effects on a spacecraft, or any large object, falling into a large, rotating black hole like Sagittarius A*. </p><p> <img alt="" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" src="https://images.theconversation.com/files/252535/original/file-20190104-32124-bu84m7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/252535/original/file-20190104-32124-bu84m7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/252535/original/file-20190104-32124-bu84m7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/252535/original/file-20190104-32124-bu84m7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/252535/original/file-20190104-32124-bu84m7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/252535/original/file-20190104-32124-bu84m7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/252535/original/file-20190104-32124-bu84m7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w"></p><p> <em>The fictional Miller's planet orbiting the black hole Gargantua, in the movie 'Interstellar.' </em><a class="source" href="http://interstellarfilm.wikia.com/wiki/Gargantua" target="_blank">interstellarfilm.wikia.com</a></p><h2>Not even a bumpy ride?</h2><p>What she discovered is that under all conditions an object falling into a rotating black hole would not experience infinitely large effects upon passage through the hole's so-called inner horizon singularity. This is the singularity that an object entering a rotating black hole cannot maneuver around or avoid. Not only that, under the right circumstances, these effects may be negligibly small, allowing for a rather comfortable passage through the singularity. In fact, there may no noticeable effects on the falling object at all. This increases the feasibility of using large, rotating black holes as portals for hyperspace travel. </p><p>Mallary also discovered a feature that was not fully appreciated before: the fact that the effects of the singularity in the context of a rotating black hole would result in rapidly increasing cycles of stretching and squeezing on the spacecraft. But for very large black holes like Gargantua, the strength of this effect would be very small. So, the spacecraft and any individuals on board would not detect it. </p><p> <img alt="" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" src="https://images.theconversation.com/files/252558/original/file-20190105-32154-ve1zfw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/252558/original/file-20190105-32154-ve1zfw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=266&fit=crop&dpr=1 600w, https://images.theconversation.com/files/252558/original/file-20190105-32154-ve1zfw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=266&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/252558/original/file-20190105-32154-ve1zfw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=266&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/252558/original/file-20190105-32154-ve1zfw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=334&fit=crop&dpr=1 754w, https://images.theconversation.com/files/252558/original/file-20190105-32154-ve1zfw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=334&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/252558/original/file-20190105-32154-ve1zfw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=334&fit=crop&dpr=3 2262w"></p><p> <em>This graph depicts the physical strain on the spacecraft's steel frame as it plummets into a rotating black hole. The inset shows a detailed zoom-in for very late times. The important thing to note is that the strain increases dramatically close to the black hole, but does not grow indefinitely. Therefore, the spacecraft and its inhabitants may survive the journey. </em><em>Khanna/UMassD</em></p><p>The crucial point is that these effects do not increase without bound; in fact, they stay finite, even though the stresses on the spacecraft tend to grow indefinitely as it approaches the black hole. </p><p>There are a few important simplifying assumptions and resulting caveats in the context of Mallary's model. The main assumption is that the black hole under consideration is completely isolated and thus not subject to constant disturbances by a source such as another star in its vicinity or even any falling radiation. While this assumption allows important simplifications, it is worth noting that most black holes are surrounded by cosmic material – dust, gas, radiation. </p><p>Therefore, a natural extension of <a href="https://doi.org/10.1103/PhysRevD.98.104024" target="_blank">Mallary's work</a> would be to perform a similar study in the context of a more realistic astrophysical black hole. </p><p>Mallary's approach of using a computer simulation to examine the effects of a black hole on an object is very common in the field of black hole physics. Needless to say, we do not have the capability of performing real experiments in or near black holes yet, so scientists resort to theory and simulations to develop an understanding, by making predictions and new discoveries.<img alt="The Conversation" height="1" src="https://counter.theconversation.com/content/107062/count.gif?distributor=republish-lightbox-basic" width="1"></p><p><a href="https://theconversation.com/profiles/gaurav-khanna-594989" target="_blank">Gaurav Khanna</a>, Professor of Physics, <em><a href="http://theconversation.com/institutions/university-of-massachusetts-dartmouth-1658" target="_blank">University of Massachusetts Dartmouth</a></em></p><p>This article is republished from <a href="http://theconversation.com" target="_blank">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/rotating-black-holes-may-serve-as-gentle-portals-for-hyperspace-travel-107062" target="_blank">original article</a>.</p>
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Ask a NASA astronomer! How did Stephen Hawking change the world?
Stephen Hawking was one of the greatest scientific and analytical minds of our time, says NASA's Michelle Thaller.
30 May, 2018
Stephen Hawking was one of the greatest scientific and analytical minds of our time, says NASA's Michelle Thaller. She posits that Hawking might be one of the parents of an entirely new school of physics because he was working on some incredible stuff—concerning quantum entaglement— right before he died. He was even humble enough to go back to his old work about black holes and rethink his hypotheses based on new information. Not many great minds would do that, she says, relaying just one of the reasons Stephen Hawking will be so deeply missed. You can follow Michelle Thaller on Twitter at @mlthaller.
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