Tag: Black Holes

Black holes and Wormholes, what are they, how are they alike and how are they different?

Did you ever stop to think about how you would describe a straight line? Sounds easy, but be honest, you’ll probably end up calling it a line that isn’t curved or something similar. Describing it as what it’s not rather than what it is. Even my American Heritage Dictionary defines straight as extending continuously in the same direction without curving.

The Greek mathematician Euclid used the concept of a straight line as the foundation of his geometry. So much so that a space that allows the existence of a true straight line is now known as a Euclidean space. (Credit: SlidePlayer)

A straight line seems like something so intuitive that we scarcely give it a second thought. In fact the Greek and other classical mathematicians like Pythagoras or Euclid just defined a straight line as the shortest distance between two different points and then extending out to infinity in both directions from there.

So obvious, yet so difficult to put into words was the concept of a straight line that nobody really thought about the problem until Einstein. You see in his Special Theory of Relativity Einstein had developed the concept of space-time that recognized that measurements of both time and space looked different to observers who were traveling at close to the speed of light relative to each other. Then, as he tried to incorporate the force of gravity into his ideas he found that he could describe the path of a particle in a gravitational field as following the straightest possible line in a ‘curved space-time’. The core principle of the general theory of relativity is that gravity bends space and therefore a truly, that is Euclidean straight line can only exist in an empty Universe.

In Special Relativity time is treated as a dimension like the three dimensions of space. For every observer a light cone extends into both the future and the past. Only events that occurred within that cone can definitely be said to occur in the past or future. Everything else is indeterminate! (Credit: Byjus)

In 1915 mathematician Karl Schwarzschild, not Einstein found an analytic solution to Einstein’s general field equations that indicated that a gravitational field could become so strong that it would bend space-time a full 90º. In that case later physicists realized that any object, even a particle of light that got too close would never be able to get back out, it would just continue falling forever into what became known as a black hole. Just to give you an idea of how concentrated the gravitational field of a black hole is you would have to take the entire mass of our Sun, 300,000 times the mass of the Earth and squeeze it down to just about one and a half kilometers in radius for it to form a black hole, and you would have to squeeze the mass of Earth down to less than half a centimetre to make it a black hole. No evidence for the existence of black holes was found during Einstein’s lifetime and he himself was never sure whether they were real or just a theoretical oddity, Schwarzschild died in WW1 just months after making his discovery so he never even considered the problem. It’s really only in the last few decades that enough evidence has accumulated to convince the majority of physicists that black holes are real.

Schwarzschild’s solution for a point mass to the field equations of General Relativity. When the distance to the point mass r equals twice the mass, r=2m, the second term on the right explodes. This point is formally known as a ‘Schwarzschild Singularity’ or more popularly the event horizon of a black hole! (Credit: R. A. Lawler)

Then in 1935 Einstein and his assistant Nathan Rosen were considering the problem of the fields associated with elementary particles. They were trying to describe elementary particles as something very similar to a black hole when they mathematically derived a formula for a black hole in one ‘space’ connecting up with another black hole in another ‘space’. Formally this is known as an Einstein-Rosen bridge but the concept has popularly become known as a wormhole in space.

Basic geometry of a Einstein Rosen bridge. The two planes represent different regions of ‘normal’ space or perhaps two entirely different Universes? (Credit: SlideShare)
It was actually in one of Einstein’s attempts to remove the ‘Schwarzschild Singularity’ that he and Nathan Rosen discovered wormhole. (Credit: Pinterest)

Wormholes have become known to all Science Fiction fans as a shortcut through space, a path between two distant places in the Universe that is shorter than an Einstein straightest possible line in normal space. A wormhole would therefore be one way to circumvent the cosmic speed limit imposed by the velocity of light. All a space traveler has to do is drop inside a wormhole and come out in some part of space that is thousands, or millions or billions of light years away. Since the distance through the wormhole is shorter than the distance in normal space you’re not actually going faster than light even though you’re getting there faster than a beam of light could.

The whole plot of ‘Star Trek Deep Space 9’ was built around a wormhole near the planet Bajor. (Credit: Pinterest)

Now it took a long time for astronomers to gather enough evidence to support the idea of black holes but that was easy compared to finding evidence for wormholes, at present there is simply none. One of the difficulties is that from the outside, and thousands of light years away, how can you tell the difference between a wormhole and a black hole? In fact it is quite possible that some of the black holes we know about, say the supermassive one at the center of the Milky Way, could actually be wormholes connecting up to other black holes elsewhere in the Universe.

The first ever image made of a black hole. Or is it really just one side of a wormhole? (Credit: NPR)

Now a team of theoretical physicists at Central Astronomical Observatory Pulkovo in Saint Petersburg Russia has published a paper in the Monthly Notices of the Royal Society where they discuss certain characteristics of wormholes that should allow astronomers to distinguish them from black holes. The key difference between the two types of object of course is that while even light can’t come back out of a black hole a wormhole allows two-way traffic. That is, things can go into this end of a wormhole and come out the other while things that go into the other end can come out of this end.

Travel through a wormhole is a dream of science fiction but could it also be a reality? (Credit: Live Science)

 The Russians considered two possibilities; the first was that gas flowing in from both ends could collide in the middle of the wormhole. Those collisions would generate heat and that heat could be detected as a recognizable spectrum of gamma rays. The second possibility was that the gravitational fields of objects on the other side of the wormhole might leak through and effect the motions of objects on this side. In fact it was by observing the motions of stars at the center of our galaxy that the supermassive black hole there was first discovered.

The postulated gamma ray spectrum emitted from a wormhole. (Credit: Piotrovich et al 2020)

Now this paper is about theoretical calculations, astronomers have not yet begun to search for the predicted signs of a wormhole coming from what are presently considered to be black holes. There is a growing interest in black holes throughout the astronomical community however so I’ll bet it won’t be long before somebody starts searching. In fact a quick and cheap way to start the search would be to re-examine existing data already taken of black holes.

Originally called Quasars, Active Galactic Nuclei generated by supermassive black holes have been studied for more than 60 years. Could a re-examination of all that data actually show that they are wormholes? (Credit: Astronomy Magazine)

How long it will take before wormholes are discovered is anybody’s guess at present. However, considering the length of time it took for the existence of black holes to be accepted it could take quite a long time. Still, if wormholes are proven to exist it would be further proof, if any more were needed, that the Universe in which we live is a truly weird and wonderful place.

The Nobel Prizes for Science in 2020 are Announced.

Early October is always that time of year when we all take a moment from the mundane news to recognize those scientists who are making fundamental contributions to our knowledge of the world around us. The cause of this annual ceremony is of course the announcement of the winners of the Nobel Prizes for the natural sciences of Physics, Chemistry, and Physiology.

The Nobel Prize. Oh, there’s also about a million bucks involved as well. (Credit: Phys.org)

This year the Physiology, i.e. Medicine prize was announced first and has been awarded jointly to Harvey J. Alter, Charles M. Rice, both of the United States, along with British Born Michael Houghton. Fittingly in this year of the Covid-19 pandemic the work for which these three scientists have been recognized deals with the identification of and drug treatments for the deadly viral disease, Hepatitis C.

This Year’s prize winners for Medicine are (left to right) Harvey J. Alter, Michael Houghton and Charles M. Rice. (Credit: Firstpost)

Hepatitis in general is classified as an inflammation of the liver and is most commonly caused by one of five different viruses giving rise to Hepatitis A, B, C, D and E. Of these Hepatitis A and B were the first to be studied and vaccines are now available to provide immunity against those forms of the disease. The cause of Hepatitis C however remained elusive for many years, making the search for effective means of treatment difficult.

Hepatitis is really several diseases that all cause an inflammation of the liver. Hepatitis is a very serious disease that if left untreated often results in death. (Credit: DW)

It was in the 1960s that Doctor Alter succeeded in demonstrating that Hepatitis C was in fact a completely different disease from the types known at that time, A and B. Due to Alter’s work Hepatitis C was for a time actually known as Hepatitis ‘non-A’, ‘non-B’.

Following up on Alter’s work Doctor Houghton then was able to isolate the genetic structure of a previously unknown virus in Hepatitis patients. Finally it was Doctor Rice who showed that the new virus alone could cause Hepatitis. Once the cause of Hepatitis C was known tests and treatment techniques could be developed for the virus so that today Hepatitis C is a treatable disease.

Like all viruses the Hep C virus is simply a strand of genetic material, RNA in this case, surrounded by a protective shell of proteins and lipids. (Credit: Wikipedia)

The Physics prize came second and was also awarded to a trio of scientists. Sir Roger Penrose of Oxford University in the UK received half of the award while Reinhard Genzel of Germany and Andrea Ghez of the United States shared the other half. The three were all honoured for their pioneering work on Black Holes.

The 2020 Nobel Physics recipients are (left to right) Sir Roger Penrose, Reinhard Genzel and Andrea Ghez. (Credit: Hindustan Times)

In fact it was Sir Roger, along with the late Stephen Hawking who were the first physicists to take seriously the idea that the odd solutions to Einstein’s field equations might have a physical reality. (Einstein himself could never made up his mind on whether or not black holes existed.) Penrose and Hawking spent decades mathematically working out the details of what a black hole would look like (pun intended). For much of that time they continued working despite the fact that there was absolutely no observational evidence to confirm any of their theories.

Perhaps the two men most associated with Black Holes. Stephen Hawking (l) and of course Albert Einstein. (Credit: ABC)

In fact much of the first evidence for black holes came from the work of Genzel and Ghez who were investigating the supermassive object at the center of our galaxy known as Sagittarius A. Using some of the world’s largest telescopes Genzel and Ghez developed techniques to see through the clouds of gas in the Milky Way’s center. Those techniques enabled them to study Sagittarius A and demonstrate that it was an immense black hole, confirming many of the theories of Penrose and Hawking. Supermassive black holes like Sagittarius A are now thought to exist at the center of every large galaxy.

In the constellation of Sagittarius lies the center of our Milky Way galaxy. There sits a supermassive black hole millions of times as massive as our Sun. (Credit: NASA)

So if Sir Roger is now getting a Nobel Prize why isn’t Hawking? The answer to that question is easy, he’s dead and according to the terms of Alfred Nobel’s will that set up the Nobel prizes only living persons can receive the award. If you think that’s not fair, well it really isn’t. However, this is actually not the first time that a scientist has died before his work was sufficiently confirmed to be considered for the prize.

Actually I rather doubt that any of this year’s physics recipients would have won their awards if it hadn’t been for last year’s ‘photograph’ of a black hole, see my post of 17 April 2019. That image was the confirmation of many theories about black holes and undoubtedly convinced the Nobel committee that it was time for researchers studying black holes to finally be recognized.

The first ‘photo’ of a Black Hole, actually taken at microwave frequencies. This is the supermassive black hole in M87 and the accretion disk around it. (Credit: NPR)

No such prompting was required in order to choose the recipients of this year’s chemistry prize. Emmanuelle Charpentier of the Max Planck Institute in Berlin and Jennifer A. Doudna were honoured for their work on the gene editing tool CRISPR. See my posts of 5 August 2017, 1 December 2018 and 18 Aug 2019 for discussions of just how enormous a breakthrough CRISPR is.

CRISPR is the most accurate and precise tool yet discovered for the editing of genetic material. (Credit: YouTube)

The award to Doctors Charpentier and Doudna is unusual for several reasons. One reason is that the first major papers describing CRISPR were published less than a decade ago in 2011 and 2012. Nobel prizes are normally awarded for work that dates back several decades, remember what I said about Roger Penrose and Stephan Hawking above. This is in order to make certain that a great deal of conformational evidence has been accumulated supporting the work before the prize is awarded.

Over the last half dozen years however CRISPR has proven to be such a marvelous tool for genetic studies that the evidence of its importance is overwhelming. CRISPR has given science the most precise and useful tool that it has ever had for literally changing the code of life itself and we are only at the beginning of understanding all that it can do.

The other reason that this year’s chemistry prize is notable is because it represents the very first time that two women have shared the prize. It is unfortunately true that the majority of Nobel Prize winners are white men, with a small number of Asian men thrown in.

Like Hypatia of Alexandria Women have often made important contributions to science and mathematics. (Credit: Historic Mysteries)

Personally I want both greater female and minority participation in the sciences because the more scientists we have, whatever their colour or sex, the more discoveries we will get. For that reason I congratulate Doctors Charpentier and Doudna and hope that other women will soon join them in making equally important advances in our understanding of the Universe. Like Doctors Alter, Rice, Houghton, Penrose, Genzel and Ghez, and hey, let’s not forget Hawking, they all deserve our recognition for their work of discovery. 

Gamma Ray Bursts are the most powerful events ever observed in the entire Universe. Could one ever be a threat to life here on Earth?

Ever since Galileo first pointed his telescope into the night’s sky astronomers have continued to discover ever stranger and more fascinating objects inhabiting this Universe of ours. Surely among the most mysterious are the objects known as Gamma Ray Bursts (GRBs).

What is a GRB? Well, about once a day, somewhere in the Universe an event occurs that releases as much energy in a few seconds as our Sun will generate in its entire life! This energy is observed as a bright burst of gamma rays. For decades little was known about GRBs and it’s only in the last 22 years that astronomers and astrophysicists feel that they have begun to understand something about these strange entities.

Gamma Ray Bursts are thought to be the most energetic events in the entire Universe! (Credit: Futurism)

Even the discovery of GRBs was pretty unusual. It is a fact that GRBs are the first, and so far only astronomical discovery to be made by CIA spy satellites. You see it all started in 1963 when the old Soviet Union agreed to the Nuclear Test Ban Treaty that ended the above ground testing of nuclear weapons. The US didn’t quite trust the Russians however; it was thought that the Soviet’s might try to cheat the ban by testing their weapons in outer space. So the CIA launched a series of satellites known as Vela that were designed to detect the sort of gamma radiation that would accompany any nuclear explosion off the Earth.

With the signing of the Nuclear Test Ban Treaty in 1963 the World’s Atomic powers agreed to halt above ground tests of nuclear weapons. (Credit: YouTube)

On July 2 in 1967 the Vela 2 and Vela 3 satellites detected a quick burst of gamma rays but it was soon realized that the burst wasn’t caused by the Russians. Using the data from the two satellites scientists at Los Alamos Nation Laboratory found that the radiation had come from somewhere outside of the solar system. Other bursts were soon detected as well but since the entire Vela program was classified as Top Secret astronomers didn’t get to hear about the discovery until 1973.

The VELA gamma ray detecting satellites were launched into space to monitor the Soviet Union’s Compliance with the Nuclear Test Ban Treaty. Instead they discovered the existence of Gamma Ray Bursts. (Credit: Flickr)

Even after the world’s astronomers knew about the existence of gamma ray bursts progress in understanding them was very slow. Think about it, since gamma rays are blocked by Earth’s atmosphere GRBs can only be detected by specialized satellites. Add to that the fact that GRBs rarely last more than a minute and that they can appear in any part in the sky and you can understand how hard it was to obtain any real data about them. 

The Earth’s Atmosphere blocks most forms of electromagnetic radiation allowing only visible light and radio waves to reach the surface. (Credit: Pinterest)

What astronomers wanted to learn most of all was whether or not GRBs had any other electromagnetic component to them. That is, did an optical, radio or perhaps X-ray flash accompany the gamma ray emissions. In order to do this astronomers had to develop a fast reaction network that would quickly communicate the news that a GRB had been detected to astronomers around the world so that other instruments could be brought in action.

Success finally came in February 1997 when the satellite BeppoSax detected GRB 970228 (GRBs are named by the date of their detection YY/MM/DD). Within hours both an X-ray and an optical glow were detected from the same source, a very dim, distant galaxy. Further such detections soon confirmed that GRBs came from such extremely distant galaxies, most of them many billions of light years away. So distant are the locations of GRBs that in order to appear so bright in our sky they must be the most powerful explosions in the entire Universe.

The BeppoSAX Satellite was designed and launched specifically to study GRBs. (Credit: SlidePlayer)

So what are these GRBs? What makes them so energetic? To be honest there’s still a lot to be learned but a consensus of opinion is growing that there are actually two distinct types of GRBs.

Those that last for a somewhat longer length of time, longer than 30 seconds, are the initial stages of a core collapse supernova. That is the death of a star so massive that it never really settled down like a normal star but instead just implodes after a few million years into a black hole. All of the well-studied GRBs fit this model remarkably well, including their location within galaxies that are undergoing rapid star formation, places where such massive, short-lived stars are far more common.

One interesting feature of this model is that as the star collapses it rotates much more rapidly, just as an ice skater will do when they pull in their arms during a spin. This increase in rotation speed generates a enormous magnetic field at the star’s poles causing the gamma rays that are emitted to squirt out from the poles like the beams of light from a lighthouse. This concentrates the power of the gamma rays into two narrow beams making the GRB look much brighter in the directions those beams travel.

The energy of long duration GRBs is concentrated into two narrow beams light the light from a lighthouse. (Credit: AAS Nova)

If this lighthouse feature of GRBs is true that implies that we are only seeing a small fraction of all GRBs, only those that are pointing at us. It also means that GRBs are not quite as powerful since their energy is focused into the beams. Again, this model fits the data collected for longer duration GRBs that make up about 70% of those that have been observed.

There are also short term GRBs, whose duration averages less than half a second and which make up about 30% of the total observed. Because they are fewer in number and shorter in duration these GRBs are harder to study and therefore less well understood. Several models have been suggested for them but the recent simultaneous observation of a GRB (GRB170817A) only 1.7 seconds after a gravity wave was detected by the LIGO gravity wave observatories implies a direct connection. Based on the nature of the gravity wave observed the event was a merger of two neutron stars. Therefore at least some short period GRBs are the result of neutron stars colliding to form a black hole or a black hole devouring a neutron star.

A Merger of Neutron Stars releases both a GRB and power Gravity waves. (Credit: AAS Nova)

So, if these GRBs are the most powerful explosions in the entire Universe, could they be any danger to us? Are their any stars in our galactic neighborhood that could collapse and generate a GRB? And what damage would a nearby GRB do?

In fact there are a couple of possible candidates known to astronomers. The stars Eta Carinae and WR 104 are both hugely massive stars that could collapse into black holes sometime in the next million or so years. Of the two WR 104 is closest at a distance of only 8,000 light years.

Eta Carena (l.) and WR104 (r.) are the most most massive and powerful stars known. Either couls someday collapse into a black hole triggering a GRB. (Credit: Gresham College)

If WR 104 were to generate a GRB, and if that GRB were aimed at Earth our atmosphere would protect us from the initial burst of gamma and X-rays, only a spike in the Ultra-violet lasting a few minutes would be seen. The long-term effects are much less pleasant however because the gamma and X-rays striking the atmosphere would cause oxygen and nitrogen to combine to form nitrogen oxide and nitrogen dioxide gasses. Both of these gasses are known destroyers of ozone, the form of oxygen in the upper atmosphere that protects us from the Sun’s UV rays. Also the gasses could combine with water vapour in the air to form droplets of nitric acid that would rain down causing further damage.

The Earth’s Ozone layer protects us from the cancer causing UV light from the Sun. Credit: UCAR)

Of course all of that is just speculation, we really have no idea what would happen here if a GRB from a star as close as WR 104 should strike the Earth. Before you start to panic however remember that GRBs are very rare, only one per day in the entire Universe. Let’s be honest, we’re a far greater danger to ourselves than Gamma Ray Bursts are!

Astronomers succeed in taking first Picture of a Black Hole

First Picture of a Block Hole (Credit: Event Horizon Telescope Collaboration)

Yes it’s true; you can’t see a black hole. The glowing doughnut shape in the image above is actually the swirling mass of gas and dust that is falling into the black hole. Astronomers call that whirlpool an accretion disk and the energy released by that matter as it drops into the gravitational well of the black hole causes the disk to glow. Also, the actual image that you see above wasn’t really taken in visible light. Rather it’s a computer-generated image converted from measurements of radio emissions across the region around the black hole.

In fact it took eight radio telescopes and more than three hundred astronomers working together in a group known as the Event Horizon Telescope Collaboration to collect the signals from the black hole needed to construct the image. The eight radio telescopes which make up the Event Horizon Telescope (EHT) are spread around the half the world; see map below. By combining the received signals of those telescopes the astronomers succeeded in constructing a single radio telescope whose resolution was equivalent to a telescope that would be nearly the size of the Earth. (The resolution of a telescope is its ability to separate two objects that are both very far away and very close together.)

The Eight Radio Telescopes that were combined to produce the Black Hole Image Span half the World (Credit: EHT)

The technique used to combine the eight signals is know as Very Long Baseline Interferometry (VLBI) and networks the telescopes by adding their signals together, allowing them to interfere with each other, remember these signals are waves, exactly as they would in a telescope as big as the distance between the telescopes. In order to add the signals together properly they must have been received at precisely the same time. This means that each radio telescope in the EHT must be governed by its own atomic clock, and all eight atomic clocks must have been synchronized before the first signals were received.

The Combined Array for Research in Millimeter-wave Astronomy (CARMA) is just one of the eight telescopes that make up the Event Horizons Telescope (Credit: University of Chicago, Department of Astronomy and Astrophysics)

That degree of precision was necessary because the black hole whose image was taken sits 55 million light-years away in the galaxy known as M87 or Virgo A and the size of the black hole is about the same as the orbit of Pluto while the size of the accretion disk is about eight times larger. In addition to producing the image the measurements made by the EVT allowed a more precise measurement of the black hole’s mass, a whopping 6.5 billion times the mass of our Sun.

The Galaxy M87 which contains the first Black Hole ever Images (Credit: The Daily Galaxy)

All that work was certainly worth the effort. That one image confirms much of the theoretical work that has been conducted regarding black holes over the last thirty to forty years. The black hole’s event horizon, the energy emitted by the accretion disk as matter flows into the black hole, they’re all there, just as the models predicted.

What the Theories said a Black Hole looked like. Turned out they were Right! (Credit: Science)

The importance of the image is that it confirms one of the strangest predictions of Einstein’s General Theory of Relativity, the very existence of black holes. Now however, the researchers hope to use the EVTC to probe closer to the event horizons of black holes in order to test the limits of the General Theory. Even after one hundred years physicists have still been unable to integrate General Relativity with Quantum Mechanics, the other great theory of modern physics. The possibility that observations of black holes by the EVT may discover some clue leading to that unification is very enticing.

The astronomers also hope to learn more about the supermassive black holes that sit in the center of every galaxy. At the moment we don’t even know for certain which comes first, the galaxy or the black hole in its center but there are theories of galactic evolution that start in both directions. Maybe EVTC will find the evidence to answer that question.

As their next step the members of the EVTC are planning on trying to obtain images of the black hole that sits at the center of our own galaxy. Since our black hole is a lot closer, only 30,000 LY away you might wonder why the astronomers didn’t start with our black hole. You have to remember however, that to see the center of the Milky Way you have to look through most of the galaxy’s disk. In other words that black hole may be closer but there’s a lot more stuff in the way!

Looking towards the center of the Milky Way there’s a lot of other stuff between us and that Black Hole (Credit: Harvard CfA)

So the first image of a black hole that was taken by the EVT is really just a first step. There are many black holes to be studied out there, which means many more discoveries just waiting for the EVT to make.

 

LIGO detects third set of Gravitational Waves

The Laser Interferometer Gravity wave Observatory (LIGO) has recently announced its third detection of gravity waves, further conformation of Einstein’s General Theory of Relativity. Actually, since the gravity waves that were detected came from a merger of two black holes this announcement confirms two of Einstein’s predictions, gravity waves and black holes.

The LIGO antennas, I think of them as antennas for gravity waves, are the world’s most sensitive instruments of any kind and they have to be since gravity waves are so weak. Even the initial design of the LIGO detector wasn’t able to detect gravity waves. It was only after a program to enhance the sensitivity that LIGO succeeded in the first ever detection of gravity waves in September of 2015. (The success was announced in May of 2016)

In fact the LIGO detectors are so sensitive that a car driving down the road a kilometer away can produce a false reaction. That’s why we have to have two LIGO detectors, located far apart. One of the instruments is in Hanford Washington and the other in Livingston Louisiana. Only if both instruments detect a signal at the same time is it a real gravity wave.

How the LIGO detectors do their job can be understood by examining the picture below. (Credit for the picture goes to : By Abbott, B. P. et al. – Observation of Gravitational Waves from a Binary Black Hole Merger B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration)Phys. Rev. Lett. 116, 061102 doi:10.1103/PhysRevLett.116.061102, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=46922746)

 

Diagram of LIGO Detector

The light produced by a 20 watt Nd:YAG laser is split into two beams, one of which bounces back and forth to the east-west direction over a 4 kilometer path while the other bounces to the north-south along an equal path. Now let’s assume a gravity wave comes along going from east to west. What the gravity wave does is to compress and expand space itself in a repeating pattern. This makes the actual length of the east-west arm vary with the wave while the north-south arm is unaffected. By bringing the beams back together and letting them interfere with each other the gravity wave can be detected.

The two black holes that merged are estimated to have had masses of 32 and 19 times the mass of the sun but when they came together 2 entire solar masses were converted into gravitational energy leaving a single black hole with a mass of 49 solar masses. A picture of what the merger may have looked like is below.

Artists Rendering of Black Hole Merger (Credit Caltech)

This latest detection is also significant because the two LIGO detectors, have been able to compare their data to estimate the location of the black hole merger in our sky. While they’ve only narrowed the location down to 3% of the sky it’s still a remarkable advancement.

And things are going to improve even more very soon. A new gravity wave detector is almost completed in Italy and a fourth is under construction in India. With four instruments spread around the world our ability to narrow in on where the gravity waves are coming from will continue to improve.

If you’d like to read more about LIGO and it’s latest discovery I recommend you visit the LIGO website by clicking the link below.

https://www.ligo.caltech.edu/news/ligo20170601