Why is it cold inside a black hole?
Because of the fuzziness of quantum particles, energy cannot be completely bound by a black hole's event horizon. Sometimes energy can escape its gravitational prison through a process known as Hawking radiation. The amount of energy that escapes is tiny, but it means that black holes have a (very cold) temperature.
When we take quantum mechanics into account, black holes can emit light and other particles through a process known as Hawking radiation. Since a "quantum" black hole emits heat and light, it therefore has a temperature. This means black holes are subject to the laws of thermodynamics.
The most massive black holes in the Universe, the supermassive black holes with millions of times the mass of the Sun will have a temperature of 1.4 x 10-14 Kelvin. That's low. Almost absolute zero, but not quite.
The short answer is probably not, though the mathematics of the universe doesn't quite rule it out. By themselves, the only thing at the center of a black hole is a singularity — a point of infinite density. In theory, however, a black hole may be paired with a mirror twin, called a white hole, to form a wormhole.
Near a black hole, the slowing of time is extreme. From the viewpoint of an observer outside the black hole, time stops. For example, an object falling into the hole would appear frozen in time at the edge of the hole.
The dead star at the center of the Red Spider Nebula has a surface temperature of 250,000 degrees F, which is 25 times the temperature of the Sun's surface. This white dwarf may, indeed, be the hottest object in the universe.
The giant black hole is already huge and due its massive size, it can sustain the diet of one sun a day. According to Christopher Onker, the lead author of a study published in Monthly Notices of the Royal Astronomical Society, the black hole is growing by 1 per cent every one million years.
But a satiated black hole effectively has zero temperature, barring a trickle of particles released by a process called Hawking radiation, meaning it could potentially act as a cold sun, says Opatrný.
Anything outside this surface —including astronauts, rockets, or light—can escape from the black hole. But once this surface is crossed, nothing can escape, regardless of its speed, because of the strong gravitational pull toward the center of the black hole.
Hawking to the rescue
In the 1970s, theoretical physicist Stephen Hawking made a remarkable discovery buried under the complex mathematical intersection of gravity and quantum mechanics: Black holes glow, ever so slightly, and, given enough time, they eventually dissolve.
Do atoms exist in black holes?
Black holes have a LOT of mass, which is why they have so much gravity. So much, in fact, that atoms are actually crushed to fill in the empty space. Sometimes a dying star has enough mass (and gravity) to crush atoms, but not quite enough to keep light from escaping.
A black hole is a region where spacetime is so curved that every possible path which light could take eventually curves and leads back inside the black hole. As a result, once a ray of light enters a black hole, it can never exit. For this reason, a black hole is truly black and never emits light.
Eventually, as the universe ages, the material around a black hole will run out and its doomsday clock will start ticking. As a black hole evaporates, it slowly shrinks and, as it loses mass, the rate of particles escaping also increases until all the remaining energy escapes at once.
Black holes have two parts. There is the event horizon, which you can think of as the surface, though it's simply the point where the gravity gets too strong for anything to escape. And then, at the center, is the singularity. That's the word we use to describe a point that is infinitely small and infinitely dense.
Since nothing can escape from the gravitational force of a black hole, it was long thought that black holes are impossible to destroy. But we now know that black holes actually evaporate, slowly returning their energy to the Universe.
Wormholes are shortcuts in spacetime, popular with science fiction authors and movie directors. They've never been seen, but according to Einstein's general theory of relativity, they might exist.
In 2003, astronomers detected something truly astonishing: acoustic waves propagating through the copious amounts of gas surrounding the supermassive black hole at the centre of the Perseus galaxy cluster, which is now renowned for its eerie wails. We wouldn't be able to hear them at their current pitch.
The hottest thing that we know of (and have seen) is actually a lot closer than you might think. It's right here on Earth at the Large Hadron Collider (LHC). When they smash gold particles together, for a split second, the temperature reaches 7.2 trillion degrees Fahrenheit. That's hotter than a supernova explosion.
The sun is much hotter than lava. Surface temparature of the sun is 10,000 degrees F, while Lava averages only 2000 degrees F.
How does – or doesn't – your body cope in extreme situations? The maximum body temperature a human can survive is 108.14°F. At higher temperatures the body turns into scrambled eggs: proteins are denatured and the brain gets damaged irreparably.
Can a black hole destroy a star?
Share: Scientists have studied star clusters in distant galaxies and found black holes there, intensively destroying the surrounding stars. According to scientists, this is how the process of formation of an intermediate type of these objects can occur.
No. There is no way a black hole would eat an entire galaxy. The gravitational reach of supermassive black holes contained in the middle of galaxies is large, but not nearly large enough for eating the whole galaxy.
So planets could potentially form around black holes, but that's no guarantee that they offer a life-friendly environment. On Earth, living things are hugely dependent on the light and warmth from the Sun to survive. Without the glow of a star, life around a black hole would likely need an alternative source of energy.
Theorists say it's technically possible, but it would be a weird place to live. Supermassive black holes have a reputation for consuming everything in their path, from gas clouds to entire solar systems.
It is incredibly unlikely that Earth would ever fall into a black hole. This is because, at a distance, their gravitational pull is no more compelling than a star of the same mass.
Located just under 1,600 light-years away, the discovery suggests there might be a sizable population of dormant black holes in binary systems. The black hole Gaia BH1, seen in this artist's concept near its Sun-like companion star, is the closest black hole to Earth discovered so far.
As for what exists on the other side of the singularity, some have speculated that this is a gateway to far-flung parts of our Universe or even other universes. The truth is that a singularity in a theory marks the breakdown of that theory, and the point at which it has nothing more sensible to say.
Nothing escapes a black hole. Any trip into a black hole would be one way. The gravity is too strong and you could not go back in space and time to return home. Aside from this, your body would be stretched and destroyed by the warping of space and the amount of radiation surrounding the event horizon.
A chunk of copper became the coldest cubic meter (35.3 cubic feet) on Earth when researchers chilled it to 6 millikelvins, or six-thousandths of a degree above absolute zero (0 Kelvin). This is the closest a substance of this mass and volume has ever come to absolute zero.
Therapeutic hypothermia was introduced: The body is cooled down to induce hypothermia to protect patients during open heart surgery as well as victims of strokes, seizures and liver failure. Still, 56.7 degrees is the coldest anyone has ever been and survived.
What is the coldest humans have made?
Coldest temperature ever recorded in a lab
The exact temperature scientists measured was 38 trillionths of a degree above -273 degrees Celsius — the closest that has ever been measured to absolute zero in a lab.
The universe won't expand fast enough to rip atoms apart, but if dark energy turns out to be a fact it will expand fast enough to avoid gravitational collapse. Black holes won't be ripped apart, they will just carry on as normal, as will the galaxies they belong to.
For all their extraordinary power, black holes are not immortal. They have a life cycle just like we do. Forty years ago Stephen Hawking, the world's foremost expert on black holes, announced that they evaporate and shrink because they emit radiation.
It is possible for two black holes to collide. Once they come so close that they cannot escape each other's gravity, they will merge to become one bigger black hole.
New black hole simulations that incorporate quantum gravity indicate that when a black hole dies, it produces a gravitational shock wave that radiates information, a finding that could solve the information paradox. Perhaps the most enigmatic objects in the Universe, black holes embody many unsolved paradoxes.
At the center of a black hole the gravity is so strong that, according to general relativity, space-time becomes so extremely curved that ultimately the curvature becomes infinite. This results in space-time having a jagged edge, beyond which physics no longer exists -- the singularity.
Most experts agree that the universe started as an infinitely hot and dense point called a singularity. Wait a minute. Isn't that what people call black holes? It is, in fact, and some physicists say they could be one and the same: The singularity in every black hole might give birth to a baby universe.
A mysterious cloud that somehow survived a close encounter with a supermassive black hole has now been unmasked. According to a new study of the object, called G2, it's actually three baby stars, shrouded in a thick cloud of the gas and dust from which they were born.
The event horizon of a black hole is the point of no return. Anything that passes this point will be swallowed by the black hole and forever vanish from our known universe. At the event horizon, the black hole's gravity is so powerful that no amount of mechanical force can overcome or counteract it.
When a star becomes a black hole, it still has all that mass, but now compressed down into an infinitesimally smaller space. And to conserve that angular momentum, the black hole's rate of rotation speeds up… a lot.
Do black holes have memory?
Using over decade-long research, scientists found that matter that collapses into a black hole leaves an imprint in the gravitational field of the black hole when quantum gravitational corrections are taken into account.
Black holes, as decreed by Einstein's general theory of relativity, are objects with gravity so strong that nothing, not even light, much less sound, can escape. Paradoxically, they can also be the brightest things in the universe.
Well, even though black holes are extreme in many ways, they don't have infinite mass—and it's mass that determines the force of their gravity. Some black holes—known as stellar black holes. —have about the amount of mass that very massive stars do.
Light particles can't escape a black hole but that doesn't mean they are destroyed. Once a particle of light ('photon') passes the 'event horizon' of a black hole, it can no longer escape, but there's nothing to suggest that it is destroyed.
The trite answer is that both space and time were created at the big bang about 14 billion years ago, so there is nothing beyond the universe. However, much of the universe exists beyond the observable universe, which is maybe about 90 billion light years across.
There's a limit to how much of the universe we can see. The observable universe is finite in that it hasn't existed forever. It extends 46 billion light years in every direction from us. (While our universe is 13.8 billion years old, the observable universe reaches further since the universe is expanding).
The radiation from the material masks the tiny amount of radiation escaping from the hole itself, and so what the astronomers observe is the very hot outside environment, rather than the freezing cold environment inside.
If you leapt heroically into a stellar-mass black hole, your body would be subjected to a process called 'spaghettification' (no, really, it is). The black hole's gravity force would compress you from top to toe, while stretching you at the same time… thus, spaghetti.
The singularity at the center of a black hole is the ultimate no man's land: a place where matter is compressed down to an infinitely tiny point, and all conceptions of time and space completely break down. And it doesn't really exist. Something has to replace the singularity, but we're not exactly sure what.
But black holes aren't just extremely massive, they're also incredibly fast rotators. Many black holes, from their measured spins, are spinning at more than 90% the speed of light.
Would a black hole hurt?
The fate of anyone falling into a black hole would be a painful “spaghettification,” an idea popularized by Stephen Hawking in his book “A Brief History of Time.” In spaghettification, the intense gravity of the black hole would pull you apart, separating your bones, muscles, sinews and even molecules.
According to our best theory of gravity, Einstein's theory of general relativity, your spaghettified body would eventually end up at a 'singularity' – an infinitely small and dense point at the 'bottom' of the black hole.
Bottom line: simply falling into a black hole won't give you a view of the entire future of the universe.
