Space and time are intertwined, called space-time, and gravity has the ability to stretch space-time. Objects with a large mass will be able to stretch space-time to the point where our perception of it changes, known as time dilation. The more mass an object has, the more it stretches and slows down time so something as large as Sagittarius A* – the gigantic black hole at the centre of the galaxy – would almost be able to stretch time to a point where it almost comes to a complete standstill.
Sagittarius A* has a radius of 22 million kilometres and a mass of more than four million times that of the Sun.
In other words, it is very dense.
And because it is so heavy, it has the ability to completely stretch out space-time to a point where one minute on the edge of Sagittarius A* will see 700 years pass on Earth.
Emma Osborne, an astrophysicist at the University of Southampton, told an audience at New Scientist Live: “Anything mass will stretch space-time. And the heavier something is, or the more mass it has, the more it will stretch space-time.
“If you were to stand just outside the event horizon of Sagittarius A*, and you stood there for one minute, 700 years would pass because time passes so much slower in the gravitational field there than it does on Earth.”
Some have suggested that black holes could be used for time travel.
A piece written for the University of Sussex by astrophysicist John Gribbin, co-authored with his wife Mary Gribbin said “the possibility of time travel involves those most extreme objects, black holes.
“And since Einstein’s theory is a theory of space and time, it should be no surprise that black holes offer, in principle, a way to travel through space, as well as through time.”
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Another impossible hurdle to overcome would be getting to a black hole.
The nearest black hole to our planet is located 6,523 light-years away – one light-year is 5.88 trillion miles.
The farthest humans have been from Earth is 248,655 miles (400,171 km) in 1970 as part of NASA’s Apollo 13 mission when the craft swung around the far side of the moon – it took almost three days to get there.