An illustration of a newly detected black-hole merger, whose gravitational-wave signal suggests that at least one of the black holes was misaligned with its orbital motion before merging with its partner.
There is sound in space, thanks to gravitational waves
“These waves are maddeningly weak, and their effects on the objects in spacetime are stupendously tiny. But if you know how to listen for them — just as the components of a radio know how to listen for those long-frequency light waves — you can detect these signals and hear them just as you’d hear any other sound. With an amplitude and a frequency, they’re no different from any other wave.”
You’ve likely heard that there’s no sound in space; that sound needs a medium to travel through, and in the vacuum of space, there is none. That’s true… up to a point. If you were only a few light years away from a star, stellar remnant, black hole, or even a supernova, you’d have no way to hear, feel, or otherwise directly measure the pressure waves from those objects. But they emit another kind of wave that can be interpreted as sounds, if you listen correctly: gravitational waves. These waves are so powerful, that in the very first event we ever detected, the black hole-black hole merger we saw outshone, in terms of energy, all of the stars in the observable Universe combined. There really is sound in space, as long as you know how to listen for it properly.
What would happen if a black hole collided with another ?
Thanks to a discovery just made in 2015, we don’t need to speculate about this. When two black holes collide, they merge together to make a larger black hole, but that isn’t the most interesting part.
When two black holes start to collide, they orbit around each other. The closer they get, the faster they spin. As you might know, black holes warp the fabric of space and time, and when they start moving fast enough, they can send ripples through space. We call them “gravitational waves”, and even though they are incredibly small, if your detector is sensitive enough, you can see them.
The LIGO observatory announced that they detected gravitational waves in 2015, which was truly the discovery of the decade. Einstein had predicted them a hundred years earlier, but never believed we’d be able to see them.
When a gravitational wave passes by Earth, it squeezes and stretches space. LIGO can detect this squeezing and stretching. Each LIGO observatory has two “arms” that are each more than 2 miles (4 kilometers) long. A passing gravitational wave causes the length of the arms to change slightly. The observatory uses lasers, mirrors, and extremely sensitive instruments to detect these tiny changes.
Watch the animation below to see how this works!
Lucky for us here on Earth, while the origins of gravitational waves can be extremely violent, by the time the waves reach the Earth they are millions of times smaller and less disruptive. In fact, by the time gravitational waves from the first detection reached LIGO, the amount of space-time wobbling they generated was thousands of times smaller than the nucleus of an atom!
LIGO’s Successor Approved; Will Discover Incredible New Sources Of Gravitational Waves
“The huge advance of LISA, though, will be the ability to detect objects spiraling into and merging with the supermassive black holes at the centers of galaxies. Stars and other forms of matter are constantly falling into black holes at the galactic center, both in our own galaxy and well beyond. These events often result in the ejection of matter, the acceleration of charged particles and the emission of radio and X-ray light. But they should also result in the emission of gravitational waves, and LISA will be sensitive to those. For the first time, we’ll be able to see supermassive black holes in gravitational waves.”
There’s no doubt that LIGO has given us one of the most incredible breakthroughs of the 21st century: the direct detection of gravitational waves. But as wonderful as LIGO is, so far it’s only been able to detect the very final stages of mergers of stellar mass-scale black holes, and only every few months at that. The technique of laser interferometry is sound and powerful, but properties inherent to Earth itself fundamentally limit how good LIGO can potentially be. But these restrictions go away if we go to space! Not only can we eliminate seismic noise, cease accounting for the curvature of the Earth, and get a better vacuum for free, but we can achieve much longer baselines. By sending a series of spacecraft up into orbit behind the Earth, we can detect more massive, more distant, and slower-period sources than LIGO could ever hope to see.
Fico ouvindo você falar sem parar sobre o que é certo e adequado, porque você precisa fazer isso ou não deve fazer aquilo. Não me importo com nada disso. Não ligo para as regras, para o que é certo ou errado. O que importa para mim é isto. Nós. Agora. E sei que você sente a mesma coisa.
Newest LIGO Signal Raises A Huge Question: Do Merging Black Holes Emit Light?
“The second merger held no such hints of electromagnetic signals, but that was less surprising: the black holes were of significantly lower mass, so any signal arising from them would be expected to be correspondingly lower in magnitude. But the third merger was large in mass again, more comparable to the first than the second. While Fermi has made no announcement, and Integral again reports a non-detection, there are two pieces of evidence that suggest there may have been an electromagnetic counterpart after all. The AGILE satellite from the Italian Space Agency detected a weak, short-lived event that occurred just half a second before the LIGO merger, while X-ray, radio and optical observations combined to identify a strange afterglow less than 24 hours after the merger.”
Whenever there’s a catastrophic, cataclysmic event in space, there’s almost always a tremendous release of energy that accompanies it. A supernova emits light; a neutron star merger emits gamma rays; a quasar emits radio waves; merging black holes emit gravitational waves. But if there’s any sort of matter present outside the event horizons of these black holes, they have the potential to emit electromagnetic radiation, or light signals, too. Our best models and simulations don’t predict much, but sometimes the Universe surprises us! With the third LIGO merger, there were two independent teams that claimed an electromagnetic counterpart within 24 hours of the gravitational wave signal. One was an afterglow in gamma rays and the optical, occurring about 19 hours after-the-fact, while the other was an X-ray burst occurring just half a second before the merger.
Ask Ethan: How Many Black Holes Are There In The Universe?
“The most recent LIGO event made me wonder how numerous black holes are, and that made me wonder what the sky would look like if we could see them (and, for clarity, see *only* black holes)… what is the spatial and intensity distribution of black holes compared the distribution of visible stars?”
For the third time since it began taking data, the LIGO collaboration discovered direct evidence for merging black holes in the Universe. There’s an incredible amount we’ve learned about black holes and where they’re located, however, and very little of it comes from gravitational waves. Instead, we know how black holes are made, where their progenitors are and were located, and how they’re likely to be distributed today. If we put this picture all together, we can come up with a numerical estimate for how many are likely to be present in our galaxy, along with where they’re expected to be concentrated. It’s an incredible picture!
The Laser Interferometer Gravitational-wave Observatory (LIGO) has made a third detection of gravitational waves, ripples in space and time, demonstrating that a new window in astronomy has been firmly opened. As was the case with the first two detections, the waves were generated when two black holes collided to form a larger black hole.
The newfound black hole, formed by the merger, has a mass about 49 times that of our sun. This fills in a gap between the masses of the two merged black holes detected previously by LIGO, with solar masses of 62 (first detection) and 21 (second detection).
Meu bem, me desculpe se eu estiver enganado, mas através do seus olhos percebi que você não está nada bem. Vem cá! Deixe-me envolvê-la em meu abraço. E logo após sentamos em um banquinho qualquer, ou até mesmo no chão, não ligo. Prometo ficar mexendo em seu cabelo até que sinta-se melhor. Aproveito, é claro, para dar alguns beijos em sua cabeça, afinal, amo o cheiro do seu cabelo.