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Sept 1st 2018
Cosmic Zombies: Black Holes Can Reanimate Dead Stars
Close encounters with medium-size black holes can reanimate dead stars, if only momentarily, a new study suggests.
A team of astronomers performed computer simulations to determine what happens when a burned-out stellar corpse known as a white dwarf passes close to an intermediate-mass black hole — one that harbors between 1,000 and 10,000 times the mass of Earth's sun.
The researchers determined that the black hole's powerful gravity can stretch and distort the white dwarf's previously inert innards so dramatically that nuclear-fusion processes can reignite for a few seconds, converting helium, carbon and oxygen into heavier elements
Such "tidal disruption events" (TDEs) can also generate gravitational waves, the ripples in space-time predicted by Albert Einstein a century ago and first detected directly in 2015 by the Laser Interferometer Gravitational-wave Observatory (LIGO).
to launch in 2034 — may be able to do so.
And huge amounts of material from extremely disrupted — that is, torn apart — white dwarfs can get sucked in by their killer black holes, sparking powerful radiation bursts that current telescopes are capable of detecting, according to the study.
The new results suggest a possible way to get a better handle on medium-size black holes, which have proven surprisingly difficult to study. Astronomers have found plenty of small (stellar-mass) black holes, and supermassive black holes containing millions or billions of solar masses are known to lurk at the hearts of most, if not all, galaxies. But their intermediate cousins have remained elusive to date.
"It is important to know how many intermediate mass black holes exist, as this will help answer the question of where supermassive black holes come from," study co-author Chris Fragile, a professor of physics and astronomy at the College of Charleston in South Carolina, said in a statement. "Finding intermediate mass black holes through tidal disruption events would be a tremendous advancement."
Supermassive black holes aren't great disruptors, by the way; the behemoths are likely to gobble up a white dwarf before disrupting it appreciably, the researchers wrote.
The new work is of more than just academic interest, for it describes a scenario that our own sun could end up enduring in the far future. Every star that begins its life with about 8 solar masses or fewer will end up as a superdense white dwarf. That fate awaits our sun in 5 billion years or so; after it exhausts its store of hydrogen fuel, it will bloat into a red giant and then collapse into a white dwarf.
Aug 29th 2018
How Does a Black Hole Form?
There's something inherently fascinating about black holes. Maybe it's that they're invisible beasts lurking in space that sometimes rip passing stars in half and scatter their remains. Whatever it is, these strange cosmic objects continue to captivate scientists and laypeople alike.
But where do black holes come from? How do they form, and what gives them such awesome destructive power? [Stephen Hawking's Most Far-Out Ideas About Black Holes]
Before we can answer that, we have to ask an even more fundamental question: Just what is a black hole? "Basically, it's an object or a point in space where the gravitational pull is so strong that nothing can escape from it," astrophysicist Neta Bahcall, of Princeton University in New Jersey, told Live Science. Even light waves are sucked in, which is why black holes are black.
These bizarre objects arise like phoenixes springing from the ashes of dead stars. When massive stars reach the ends of their lives, the hydrogenthat they've been fusing into helium is nearly depleted. So, these monster stars begin burning helium, fusing the remaining atoms into even heavier elements, up until iron, whose fusion no longer provides enough energy to prop up the star's outer layers, according to Swinburne University of Technology in Australia's Centre for Astrophysics and Supercomputing. These top layers collapse inward and then explode out as a powerful and bright burst called a supernova.
Yet, a small part of the star remains behind. Albert Einstein's equations of general relativity predict that if this remnant has about three times the mass of Earth's sun, the remnant star's powerful gravitational force will overwhelm everything else and the material it's made of will be crushed to an infinitely small point with infinite density, according to NASA. The known laws of physics can't actually handle such mind-bending infinities. "At some point, they break down and we don't really know what happens," Bahcall said. [8 Ways You Can See Einstein's Theory of Relativity in Real Life]
If this stellar vestige is alone, a black hole will generally just sit there not doing much. But if gas and dust surround the object, that material will get sucked into the black hole's maw, creating bright bursts of light as the gas and dust heat up, swirling around like water going down a drain. The black hole will incorporate this mass into its own, allowing the object to grow, Bahcall said.
If two black holes meet, the powerful gravity of each one will attract the other, and they will get closer and closer, spinning around one another. Their collective mass will shake the fabric of nearby space-time, sending out gravitational waves. In 2015, astronomers discovered such gravitational waves via the Laser Interferometer Gravitational-Wave Observatory (LIGO), Live Science previously reported.
"That was the first time we could actually see black holes and confirm that they exist," Bahcall said, adding that the results were also a beautiful corroboration of Einstein's predictive equations.
Scientists had found indirect evidence of black holes before, witnessing stars in the center of our Milky Way galaxy orbiting around a gigantic invisible object, Universe Today reported. How such supermassive black holes — which can have billions of times the mass of our sun — form is an outstanding question, Bahcall said.
Researchers believe that these supermassive black holes were once much smaller, forming as more modest-size black holes in the earliest days of our universe. Over cosmological time, these objects absorbed gas and dust and merged with one another to grow, ending up as colossal monsters. But many of this story's details remain fuzzy, Bahcall said.
Astronomers have observed objects called quasars, which glow brighter than thousands of galaxies put together and are thought to be powered by supermassive black holes consuming matter. Quasars have been seen back as far as the first billion years after the Big Bang, when our universe formed, leaving scientists to scratch their heads over how such enormous objects could form so quickly, Bahcall said.
"That really highlights and adds complexity to the question," Bahcall said, and it remains a very active topic of research.
Aug 13th 2018
The Wall of Death Around Black Holes Could Break Down
Physicists have insisted for a long time that black holes are impenetrable ciphers. Whatever goes in is lost, impossible to study or meaningfully understand. Some small amount of matter and energy might escape a black hole in the form of "Hawking radiation," but anything still inside the black hole is functionally disappeared from the physical universe.
The idea is a basic premise of modern physics: If something falls into a black hole, it can't be contacted, it's future can't be predicted. No observer could possibly survive traveling into the dark space, not even long enough to glance around and notice a few things before being annihilated.
Now, a team of mathematicians and physicists scattered across Portugal, Canada, the Netherlands and the United States is trying to poke a hole in the hypothesis. It's just a pinprick, but it's already sparked a rush of interest and research from their colleagues.
In a paper published Jan. 17 in the journal Physical Review Letters, the team of researchers showed that in certain extreme situations, black holes could exist that would allow theoretical observers to pass through their outer borders without being instantly destroyed. Plow your shielded spaceship into the event horizon of one of these singularities (the infinitely tiny spots into which all black holes disappear all of their matter and energy), and you might live just long enough to see what's going on inside. It's a crack in the black hole cipher, albeit a tiny one. [What Would Happen if You Fell Into a Black Hole?]
To understand why this is such a big deal to physicists, you have to understand how they think about the universe.
The notion that black holes must be walled off, that their interiors are necessarily impossible to observe, is called the cosmic censorship hypothesis. First proposed by mathematician Roger Penrose in 1969 and later debated by the likes of Stephen Hawking and Kip Thorne, it's been modified over the decades and has never been formally stated as a theory. But for certain researchers, it's something like an article of faith, backed up by how neatly it ties up certain loose ends in modern models of the universe.
But the new paper implies that in the border regions of these special black holes, cosmic censorship breaks down. An observer could travel beyond the zone of what physics can predict and watch what happens there. And if that's true, it would mean the world of physics that makes sense is starting to leak into the zone of the incomprehensible.
The universe is a future trap
To understand why this is such a big deal to physicists, you have to understand how they think about the universe.
A physicist wants the universe to work like a clockwork mechanism. Set all the initial conditions — put this star here, that planet there and a wave of energy over in that corner — and the laws of the universe dictate exactly how the whole system will evolve over any length of time. Physics assumes that every speck of matter is on a kind of invisible train track, careening from one inevitable destination to the next. Even if human beings and their supercomputers can't always predict the future, physicists generally assume the future is already determined.
Even quantum mechanics, with its weird uncertainties and deep randomness, doesn't really violate that essential physical determinism.
"With quantum mechanics, of course you don't have determinism in the sense of predicting, say, exactly when an atom is going to decay," study co-author Peter Hintz, a mathematician based at the University of California, Berkeley and a research fellow at the Clay Mathematics Institute, said in an interview with Live Science "But you can, however, predict the probability distributions of when that atom is most likely going to decay [and when it isn't likely to decay]."
The quantum-mechanical view of a universe of evolving, intersecting probability distributions is a lot wilder and more confusing than Newton's world, or even Einstein's. But it's still fundamentally deterministic. Everything in creation is trapped on its mind-bending course through the eons.
Black holes threaten to bust the trap
The one place that determinism really does break down is inside a singularity: Compress enough mass and energy together that they collapse into a single point, and Einstein's laws break down. Suddenly, the laws of physics start doing impossible things, giving answers like "infinity" to questions that must have finite answers:
What's the force of gravity at this point? Infinity. How curved is spacetime over here? Infinitely.
That's just not a situation our physics can grapple with.
Whatever does go on inside a singularity, modern physics isn't up to the task of figuring it out. And, at least according to the principle of cosmic censorship as Penrose explained it, scientists operating in our universe can't figure it out. The knowledge is forbidden by the structure of space-time: All the known singularities are either locked away beyond impenetrable event horizons of black holes or in the incomprehensible history of the first moment of the Big Bang.
If the Jan. 17 paper is just a pinprick, it's one that threatens to widen until it tears a big gash through the whole idea of cosmic censorship.
Hintz and his colleagues showed that, under certain circumstances, the wall of death around black holes could break down.
When scientists argue the case for cosmic censorship at the border regions of black holes, a critical point they make has to do with how energy behaves as it approaches a singularity.
The canonical story goes like this: Near a black Hole, Hintz told Live Science, time slows down. (You might be familiar with this phenomenon if you saw the movie "Interstellar.") [8 Ways You Can See Einstein's Theory of Relativity in Real Life]
If you shine a white light at an astronaut falling toward the event horizon, that time dilation will — from that astronaut's perspective — cause the light to appear to change. As time moves more slowly for them, but at the same rate for the flashlight pumping out wave after wave from a fixed location, the peaks of each wave will seem to arrive at the astronaut faster and faster as that astronaut moves into slower and slower regions of time near the black hole.
When the wave peaks of a beam of electromagnetic radiation (including visible light) start coming faster and faster, that means that (from the perspective of the tumbling astronaut) the frequency is getting faster. The astronaut sees the light blue-shifting as the frequency goes up and carrying more energy per second.
From the astronaut's point of view, that mild flashlight would, before long, become a scalding beam of gamma radiation, Hintz said. Then, right at the border of the region where the singularity warps space beyond recognition, where time seems to stop entirely, the frequency would spike to infinity — a zone of infinite energy, utterly unsurvivable. [Interstellar Space Travel: 7 Futuristic Spacecraft to Explore the Cosmos]
It's the last defense of comprehensible physics against the void, like the three-headed dog guarding the gates of hell: Travel here, observer, and you will be obliterated.
Charged black hole
Or maybe not. Hintz and his colleagues built a model in which the wall of blue-shifted energy would disappear.
"We study this universe where there is just one black hole, which would be a very late stage of the evolution of the universe where all of the other matter, like you and me, has decayed or disappeared into very distant singularities," he said. "It's a black, bleak place."
And this black hole they described is unusual. It has a very strong electromagnetic charge.
Under normal circumstances, strongly charged particles tend to attract one another, positive and negative, and cancel each other out. Our world has pockets of strong charge — your hair after rubbing a balloon on it for a while, for example — but any massive body tends to average out to a charge of just about zero. It's likely that not a single black hole of the kind Hintz and his colleagues studied exists in the real universe, he said.
Physicists study charged black holes, though, Hintz said, because they tend to be pretty good analogies for rapidly spinning black holes, which almost certainly do exist but are much more difficult to do calculations with.
"Charge is a poor man's angular momentum [spin]," Hintz said. They're not the same, but their effects are similar enough that physicists sometimes substitute one for another in studying black holes.
And it turns out that, in the case of a charged black hole that's charged strongly enough, another effect would overwhelm the blue shift, and might save that astronaut's life: Energy decays as it approaches the black hole, and in the case of the black hole they studied, it would actually decay faster than it blue-shifted. Instead of peaking at an infinite energy in this black hole's border region, it would peter out, harmless, at the border, the researchers said.
"If you don't die [don't get eradicated from physical existence as we know it] when you cross the horizon, then determinism breaks down, because you can't actually predict what's going to happen afterwards," Hintz said.
The idea is such a sufficiently stunning rebuke to the way physicists see the world that it provoked an almost immediate follow-up.
In a paper released on the preprint website arXiv on Jan. 29, pending peer review and publication, another team of mathematicians and physicists tackled the same question, but for a class of more normal, difficult-to-model, rapidly spinning black holes. [The Strangest Black Holes in the Universe]
Without the extreme circumstances of the charged black holes Hintz and his colleagues studied, they found cosmic censorship still intact. Beams of energy would still decay when approaching the sort of singularity they modeled, but not fast enough to prevent that deadly blue-shift. A deadly fire still burns at this much more likely border region of reality.
Hintz said it's important to understand that his and his colleague's model of the universe is "far-fetched." But this kind of abstract research can pierce widely accepted notions of reality and open up areas of inquiry in ways experimental science cannot.
"It's very hard to sort of come up with smoking-gun experimental evidence from the outside that something is going on inside of black holes," he said.
But this research shows that, regardless of whether we'll ever see it, something from our universe just might be able to take a look.
July 10th 2018
This is the brightest early universe object ever seen
A galaxy spinning around a hungry supermassive black hole that's guzzling down matter and shooting out plasma jets has grabbed the attention of astronomers 13 billion light years away. This plasma-spewing quasar is spurting out brighter radio emissions than anything else ever observed in the early universe.
The brilliant celestial object could help scientists unlock the secrets of the universe's very first galaxies. Astronomers tracked the mysterious quasar using the National Science Foundation's Very Long Baseline Array. They detailed their findings in two papers published Monday in The Astrophysical Journal and The Astrophysical Journal Letters.
"There is a dearth of known strong radio emitters from the universe's youth," study author Eduardo Bañados from the Carnegie Institute for Science said in a statement. This quasar, he added, was brighter than any other object spotted in the early universe "by a factor of 10."
This incredible brightness allowed astronomers to get a great look at the quasar, which
is called PSO J352.4034-15.3373, or P352-15 for short. "This is the most-detailed image yet of such a bright galaxy at this great distance," study author Emmanuel Momjian from the National Radio Astronomy Observatory (NRAO) added in the statement.
Although astronomers are sure they've spotted a quasar, they don't know exactly which elements they've picked up in their image. Three components jump out of the shot (below) and scientists think these correspond to one of two options.
A patch of light might on one side of the image might be the heart, with the other two smudges revealing a shooting plasma jet. Or, the bright patch in the middle is the quasar core and the other lights indicate jets bursting out from either side. Researchers think the first option—a one-sided jet—is more likely.
If they've spotted a one-sided jet, astronomers can track the object over several years to work out how fast it's expanding. If the middle object is the core, on the other hand, it could be very young, or shrouded in gas that's suffocating jet expansion.
The astronomers will have to make more observations before they'll be able to say exactly what's happening. This task, the NRAO's Chris Carilli said in the statement, is an exciting prospect.
“This quasar’s brightness and its great distance make it a unique tool to study the conditions and processes that prevailed in the first galaxies in the universe,” he said. “We look forward to unraveling more of its mysteries,” he added.
Oct 22nd 2017
Black holes are some of the strangest and most fascinating objects found in outer space. They are objects of extreme density, with such strong gravitational attraction that even light cannot escape from their grasp if it comes near enough.
Albert Einstein first predicted black holes in 1916 with his general theory of relativity. The term "black hole" was coined in 1967 by American astronomer John Wheeler, and the first one was discovered in 1971.
There are three types: stellar black holes, supermassive black holes and intermediate black holes.
Stellar black holes — small but deadly
When a star burns through the last of its fuel, it may collapse, or fall into itself. For smaller stars, up to about three times the sun's mass, the new core will be a neutron star or a white dwarf. But when a larger star collapses, it continues to compress and creates a stellar black hole.
Black holes formed by the collapse of individual stars are (relatively) small, but incredibly dense. Such an object packs three times or more the mass of the sun into a city-size range. This leads to a crazy amount of gravitational force pulling on objects around it. Black holes consume the dust and gas from the galaxy around them, growing in size.
According the Harvard-Smithsonian Center for Astrophysics, "the Milky Way contains a few hundred million" stellar black holes.
Supermassive black holes — the birth of giants
Small black holes populate the universe, but their cousins, supermassive black holes, dominate. Supermassive black holes are millions or even billions of times as massive as the sun, but have a radius similar to that of Earth's closest star. Such black holes are thought to lie at the center of pretty much every galaxy, including the Milky Way.
Scientists aren't certain how such large black holes spawn. Once they've formed, they gather mass from the dust and gas around them, material that is plentiful in the center of galaxies, allowing them to grow to enormous sizes.
Illustration of a young black hole, such as the two distant dust-free quasars spotted recently by the Spitzer Space Telescope. More photos of black holes of the universe
Supermassive black holes may be the result of hundreds or thousands of tiny black holes that merge together. Large gas clouds could also be responsible, collapsing together and rapidly accreting mass. A third option is the collapse of a stellar cluster, a group of stars all falling together.
Intermediate black holes – stuck in the middle
Scientists once thought black holes came in only small and large sizes, but recent research has revealed the possibility for the existence of mid-size, or intermediate, black holes (IMBHs). Such bodies could form when stars in a cluster collide in a chain reaction. Several of these forming in the same region could eventually fall together in the center of a galaxy and create a supermassive black hole.
In 2014, astronomers found what appeared to be an intermediate-mass black hole in the arm of a spiral galaxy.
"Astronomers have been looking very hard for these medium-sized black holes," co-author Tim Roberts, of the University of Durham in the United Kingdom, said in a statement.
"There have been hints that they exist, but IMBH's have been acting like a long-lost relative that isn't interested in being found."
Black hole theory — how they tick
Black holes are incredibly massive, but cover only a small region. Because of the relationship between mass and gravity, this means they have an extremely powerful gravitational force. Virtually nothing can escape from them — under classical physics, even light is trapped by a black hole.
Such a strong pull creates an observational problem when it comes to black holes — scientists can't "see" them the way they can see stars and other objects in space. Instead, scientists must rely on the radiation that is emitted as dust and gas are drawn into the dense creatures. Supermassive black holes, lying in the center of a galaxy, may find themselves shrouded by the dust and gas thick around them, which can block the tell-tale emissions.
Black holes are strange regions where gravity is strong enough to bend light, warp space and distort time. [See how black holes work in this SPACE.com infographic.
Credit: Karl Tate, SPACE.com contributor
Sometimes as matter is drawn toward a black hole, it ricochets off the event horizon and is hurled outward, rather than being tugged into the maw. Bright jets of material traveling at near-relativistic speeds are created. Although the black hole itself remains unseen, these powerful jets can be viewed from great distances.
Black holes have three "layers" — the outer and inner event horizon and the singularity.
The event horizon of a black hole is the boundary around the mouth of the black hole where light loses its ability to escape. Once a particle crosses the event horizon, it cannot leave. Gravity is constant across the event horizon.
The inner region of a black hole, where its mass lies, is known as its singularity, the single point in space-time where the mass of the black hole is concentrated.
Under the classical mechanics of physics, nothing can escape from a black hole. However, things shift slightly when quantum mechanics are added to the equation. Under quantum mechanics, for every particle, there is an antiparticle, a particle with the same mass and opposite electric charge. When they meet, particle-antiparticle pairs can annihilate one another.
If a particle-antiparticle pair is created just beyond the reach of the event horizon of a black hole, it is possible to have one drawn into the black hole itself while the other is ejected. The result is that the event horizon of the black hole has been reduced and black holes can decay, a process that is rejected under classical mechanics.
Scientists are still working to understand the equations by which black holes function.
Shining light on binary black holes
In 2015, astronomers using the Laser Interferometer Gravitational-wave Observatory (LIGO) made the first detection of gravitational waves. Since then, the instrument has observed several other incidents. The gravitational waves spotted by LIGO came from merging stellar black holes.
"We have further confirmation of the existence of stellar-mass black holes that are larger than 20 solar masses — these are objects we didn't know existed before LIGO detected them," MIT's David Shoemaker said in a statement. Shoemaker is the spokesperson for the LIGO Scientific Collaboration (LSC), a body of more than 1,000 international scientists who perform LIGO research together with the European-based Virgo Collaboration.
LIGO's observations also provide insights about the direction a black hole spins. As a pair of black holes spirals around one another, they can spin in the same direction or they can be completely different.
"This is the first time that we have evidence that the black holes may not be aligned, giving us just a tiny hint that binary black holes may form in dense stellar clusters," said LIGO researcher Bangalore Sathyaprakash of Penn State and Cardiff University.
There are two theories on how binary black holes form. The first suggests that they formed at about the same time, from two stars that were born together and died explosively at about the same time. The companion stars would have had the same spin orientation, so the black holes they left behind would, as well.
Under the second model, black holes in a stellar cluster sink to the center of the cluster and pair up. These companions would have random spin orientations compared to one another. LIGO's observations of companion black holes with different spin orientations provide stronger evidence for this formation theory.
"We're starting to gather real statistics on binary black hole systems," said LIGO scientist Keita Kawabe of Caltech, who is based at the LIGO Hanford Observatory. "That's interesting because some models of black hole binary formation are somewhat favored over the others even now and, in the future, we can further narrow this down."
Interesting facts about black holes
· If you fell into a black hole, theory has long suggested that gravity would stretch you out like spaghetti, though your death would come before you reached singularity. But a 2012 study in Nature suggests that quantum effects would cause the event horizon to act much like a wall of fire, instantly burning anyone to death.
· Black holes do not "suck." Suction is caused by pulling something into a vacuum, which the massive black hole definitely is not. Instead, objects fall into them.
· The first object considered to be a black hole is Cygnus X-1. Rockets carrying Geiger counters discovered eight new X-ray sources. In 1971, scientists detected radio emissions coming from Cygnus X-1, and a massive hidden companion was found and identified as a black hole.
· Cygnus X-1 was the subject of a 1974 friendly wager between Stephen Hawking and a fellow physicist Kip Thorne, with Hawking betting that the source was not a black hole. In 1990, he conceded defeat. [VIDEO: Final Nail in Stephen Hawking's Cygnus X-1 Bet?]
· Miniature black holes may have formed immediately after the Big Bang. Rapidly expanding space may have squeezed some regions into tiny, dense black holes less massive than the sun.
· If a star passes too close to a black hole, it can be torn apart.
· Astronomers estimate there are anywhere from 10 million to a billion stellar black holes, with masses roughly three times that of the sun, in the Milky Way.
· The interesting relationship between string theory and black holes gives rise to more types of massive giants than found under conventional classical mechanics.
· Black holes remain terrific fodder for science fiction books and movies. Check out the science behind the movie "Interstellar," which relied heavily on theoretical physicist Kip Thorne to bring real science to the Hollywood feature. In fact, work with the special effects of the blockbuster lead to an improvement in the scientific understanding of how distant stars might appear when seen near a fast-spinning black hole.
Feb 5th 2017
· NASA has found evidence of supermassive black holes in galaxies that formed when the universe was just 1.4 billion years old.
· This discovery could completely change our understanding of how black holes came together when the universe was just in its infancy.
FROM OUT OF THE DARKNESS
In some ways, astronomy is a lot like time travel. Even with the best telescopes, what we see now has already happened, and in some cases, it happened billions of years ago. The radiation and other signals we pick up take so long to travel to us that the farther away the event was, the longer it takes for us to know about it. Such information can provide scientists with a window into the past, and sometimes, even give us a glimpse at the very foundations of our universe.
Recently, NASA used the Fermi Gamma-Ray Space Telescope to intercept intense gamma radiation from some far away, ancient galaxies. The galaxies formed roughly 12 billion years ago and could clue us in to how black holes formed during the universe’s (relative) infancy.
The rays come from super energetic space objects call blazars, which are compact quasars. These objects are found at the centers of active elliptical galaxies that are also home to supermassive black holes. As matter falls into these black holes, they shoot out energy, which moves nearly at the speed of light. Knowing this, we can tell from where and when the energy came.
A DEEPER LOOK
Astronomers are excited by the prospect of studying such old black holes. “Despite their youth, these far-flung blazars host some of the most massive black holes known,” said Roopesh Ojha of NASA’s Goddard Space Flight Centre in a press release. He continued, “That they developed so early in cosmic history challenges current ideas of how supermassive black holes form and grow, and we want to find more of these objects to help us better understand the process.”
Tools such as the Fermi Space Telescope are allowing scientists to reach deeper into space than ever before. Subsequently, that means that we are able to look deeper into the universe’s past. But as with many huge discoveries, the findings present more questions than immediate answers. “The main question now is how these huge black holes could have formed in such a young universe. We don’t know what mechanisms triggered their rapid development,” said another team member, Dario Gasparrini of the Italian Space Agency’s Science Data Centre.
Given what we know about black holes, how these supermassive objects, which pump out two trillion times the energy of our Sun, were able to form is a mystery. Answers to questions like this will help us understand how the universe looked throughout its development, and maybe even what’s in store for the future. For now, NASA will continue to look for more blazars to study, as their orientation causes them to appear clearly on our high-powered equipment. According to Marco Ajello from Clemson University in South Carolina, “We think Fermi has detected just the tip of the iceberg, the first examples of a galaxy population that previously has not been detected in gamma rays.”
Black-holes are a space phenomenon that are no threat to human beings, there is one at the centre of our galaxy and whilst it is a strange and very violent place it has been there for a long long time and I could joke and say nobody has ever seen it, but we do know it’s there, scientists have told us.
As an example as to why it is no threat to us consider this. If our sun were to stop shining suddenly we would not be aware of it for a full eight minutes, because that is the time it takes for the light from the sun to reach us here on earth.
Now the nearest black hole is the one at the centre of our galaxy and our galaxy is many light years across, a light year is the way we measure the enormous distances across space. We cannot do this in miles, the numbers are just too big for our reasoning.
You can work it out, the sun is about 93 million miles away, and light travels that distance in eight minutes so divide a year by eight minutes and multiply that figure by 93 million miles and you get a large number of miles, that’s a light year.
It’s impractical to think of miles when you are thinking about space, distant stars are millions of light years distant from Earth, when we think about, photograph or record these stars, we are recording what they were like millions of light years ago, we don’t know what they are like today.
The biggest known black hole is four lights Days in diameter this equates to 70,000 million miles, and remember the sun is 93,million miles away from the Earth
How can we be sure that what science is telling us is actually a true picture of the universe? we know that as we go faster time actually slows down, we also know that the universe is expanding and everything that we are looking at are travelling at different speeds, and this means some parts have different times.
The world is a weird and wonderful place and if you include the universe in your thinking things get more weird and more wonderful the more you think about it.
But do not worry about such things, it has been like this for thousands of years and it's not likely to change soon.
The best way for me to give you information on black holes is to present you with a series of YouTube videos, here they are.