Time does stop at the event horizon of a black hole, but only as seen by someone outside the black hole. This is because any physical signal will get infinitely redshifted at the event horizon, thus never reaching the outside observer. Someone falling into a black hole, however, would not see time stop.
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.
Black hole news: Standing on edge of black hole would cause 700 years to pass in 1 minute.
However time does stop at the singularity at the centre of the black hole. The history of particles falling in just stop when they hit it. General relativity predicts the curvature goes to infinity, and can no longer say what happens next.
Time Can Change
In addition to gravity stretching and squashing objects, another strange phenomenon that a traveler would observe close to a black hole is something called time dilation, in which time passes slower closer to the black hole than further away.
Of course, if A "hung on" long enough before actually falling in, then A might see the future course of the universe. Bottom line: simply falling into a black hole won't give you a view of the entire future of the universe.
If you were able to travel at the speed of light, all of your motion would be wrapped up in getting you to travel at the maximum speed through space, and there would be none left to help you travel through time — and, for you, time would stop. At the speed of light, there is no passage of time.
Like part of a cosmic Russian doll, our universe may be nested inside a black hole that is itself part of a larger universe. In turn, all the black holes found so far in our universe—from the microscopic to the supermassive—may be doorways into alternate realities.
What are the chances of Earth being consumed by a black hole? Experts who spoke to Newsweek said there is practically zero chance of the Earth ever colliding with a black hole before it is swallowed by the sun in around five billion years' time.
After just a few minutes more — 21 to 22 minutes total — the entire mass of the Earth would have collapsed into a black hole just 1.75 centimeters (0.69”) in diameter: the inevitable result of an Earth's mass worth of material collapsing into a black hole.
So a black hole not only warps the space around it, but time too. “Time is going slower there by a factor of 1,000,” says Bakala. That means for every 1,000 days that pass on Earth – a little over three years – just a single day elapses on the black hole planet.
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.
Black holes are dark, dense regions in space where the pull of gravity is so strong that nothing can escape. Not even light can get out of these regions. That is why we cannot see black holes—they are invisible to our eyes. Because nothing can get out of black holes, physicists struggle understanding these objects.
The idea (in Einstein's conception) is that space and time are parts of one entity, spacetime. The presence of mass distorts and warps this spacetime; normally the warping is minor, but around a very compact object such as a black hole or a neutron star the warping is dramatic and all sorts of funky effects happen.
Black holes could take us to the future, and maybe even the past. The hard part would be surviving the trip. Black holes form natural time machines that allow travel to both the past and the future.
Some theorists have even argued for more, up to an indefinite number of possible dimensions. Other physicists suggest that experimental results have thrown cold water on the case for higher dimensions, leaving us only with the familiar three dimensions of length, width and height, plus the dimension of time.
We have even found a possible way of using AdS/CFT to make quantum computers more reliable (see “Quantum corrections”). The fact is, however, that we still haven't arrived at a holographic description of the universe we see around us.
Cosmologists aren't sure if the universe is infinitely big or just extremely large. To measure the universe, astronomers instead look at its curvature. The geometric curve on large scales of the universe tells us about its overall shape. If the universe is perfectly geometrically flat, then it can be infinite.
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. Such an event would be extremely violent. Even when simulating this event on powerful computers, we cannot fully understand it.
It would take 10100 years, or a googol, for a supermassive black hole to fully disappear. “The entire age of the universe [is] a fraction of [the time] it would take,” says Priyamvada Natarajan, a researcher at Yale University who probes the nature of black holes. “As far as we're concerned, it is eternity.”
A star has survived a close encounter with a black hole, but the black hole has been able to sneak a second bite. A captured star has experienced multiple close encounters with a supermassive black hole in a distant galaxy — and possibly even survived having material ripped away by immense gravitational tidal forces.
The faster the relative velocity, the greater the time dilation between one another, with time slowing to a stop as one approaches the speed of light (299,792,458 m/s).
Answer: Firstly, the physical consequence of traveling at the speed of light is that your mass becomes infinite and you slow down. According to relativity, the faster you move, the more mass you have. The same works on Earth when you're driving down the freeway.
It's not so much that light doesn't experience time. It's that our very concept of time doesn't even apply to light. Light doesn't even know what time is.