Normally, they are created as a particle-antiparticle pair and they quickly annihilate each other. But near the horizon of a black hole, it's possible for one to fall in before the annihilation can happen, in which case the other one escapes as Hawking radiation.
By using a chain of atoms to simulate a black hole's event horizon, researchers have shown that Hawking radiation may exist just as the late physicist described. Scientists have created a lab-grown black hole analog to test one of Stephen Hawking's most famous theories — and it behaves just how he predicted.
How do black holes emit radiation if nothing can escape?
The upshot of all this is that gravity, in addition to pulling things in, stretches and compresses them too. And this squeezing causes heating, leading to the emission of radiation long before the falling matter actually enters the black hole.
It also appears that the Universe cannot routinely produce black holes smaller than about 2.5 solar masses, so finding really small and hence hot black holes isn't an option. It's therefore likely that detecting Hawking radiation is virtually impossible.
Because Hawking radiation is composed of one half of a collection of entangled pairs, it emerges from the black hole in a completely random state—if the particles were coins, they would be observed to be heads or tails with equal probability.
According to their new approach, this radiation arises solely because of the differences in the quantum vacuum of space dependent on its curvature, and therefore Hawking radiation should be emitted by all masses in the Universe, even those without event horizons.
Is it possible for a black hole to "eat" an entire galaxy? 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.
This phenomenon was dubbed "Hawking radiation" and remains one of the most fundamental revelations about black holes. "It all started with Hawking's realization that the total horizon area in black holes can never go down.
In astrophysics, spaghettification is the tidal effect caused by strong gravitational fields. When falling towards a black hole, for example, an object is stretched in the direction of the black hole (and compressed perpendicular to it as it falls).
So the answer to your question is simply that the Hawking radiation is not composed only of photons. Hawking's original derivation predicts that whatever massless fields are propagating in the black hole spacetime will get thermal excitations produced by the black hole.
Temperature. The more massive a black hole, the colder it is. Stellar black holes are very cold: they have a temperature of nearly absolute zero – which is zero Kelvin, or −273.15 degrees Celsius.
Even these would evaporate over a timescale of up to 2 × 10106 years. Post-1998 science modifies these results slightly; for example, the modern estimate of a solar-mass black hole lifetime is 1067 years.
How close could you get to a black hole without dying?
Sarah Scoles, writing for Cornell University, estimates that 50-70 miles is a safe distance for an average-sized black hole. An orbiting object simply has to not be close enough to be torn apart by tidal forces, excessively dragged by the black hole's angular momentum, or damaged by its magnetic field.
White holes are theoretical cosmic regions that function in the opposite way to black holes. Just as nothing can escape a black hole, nothing can enter a white hole. White holes were long thought to be a figment of general relativity born from the same equations as their collapsed star brethren, black holes.
In fact, the possibility of creating a black hole in a lab is a goal that scientists are actively pursuing—one that could allow researchers to answer many fundamental questions about quantum mechanics and the nature of gravity. A black hole typically forms when a star much more massive than our sun dies.
Although it has never been directly observed, Hawking radiation is a prediction supported by combined models of general relativity and quantum mechanics. It is named after the eminent physicist Stephen Hawking, who, in 1974, published a paper titled Black hole explosions? arguing for their existence.
We're obviously not inside a stellar mass black hole. Or a super-massive black hole like the ones at the heart of many galaxies (including ours). Those are what most people think of when the term “black hole” comes up.
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. Inside a black hole is where the real mystery lies. According to Einstein's theory, time and space, in a way, trade places inside the hole.
literally nothing … can survive spaghettification. Not even spaghetti. In the vicinity of a black hole, space-time is so severely distorted that the forces found in normal matter are no longer sufficient to hold that matter together. As a result, the matter gets stretched and torn into a stream of particles.
Within any black hole is the central point, the singularity, which has infinite gravity and where mass is compressed into an infinitely small point. There, it is game over. There's no surviving.
Black holes do not go around in space eating stars, moons and planets. Earth will not fall into a black hole because no black hole is close enough to the solar system for Earth to do that.
When matter falls into or comes closer than the event horizon of a black hole, it becomes isolated from the rest of space-time. It can never leave that region. For all practical purposes the matter has disappeared from the universe.
In short, no. There's no way that a black hole could eat the universe, or even an entire galaxy, according to NASA. Here's why. Black holes are former massive stars that have collapsed back in on themselves to become incomprehensibly dense — so much so that even light can't escape them.
