INDIA: Black holes were first conceptualised in the 1700s as objects so huge that nothing could evade their gravitational pull. But Einstein’s ground-breaking theory of gravity, which was finished in 1917, is where the contemporary tale of black holes really begins.
Over the past century, scientists have created a model of what black holes must look like using Einstein’s theory of gravity (general relativity).
Black Holes
No matter how strong the light that is shone on a black hole, it never reflects back since the light is swallowed by the hole, making it the darkest place in the universe.
Any object that crosses the “horizon” of a black hole, which is a genuine “hole” in space, is swallowed up indefinitely.
Due to this, black holes are regarded as the edge of space and a one-way door out of our world; nothing within a black hole can ever, even in theory, connect with our universe again.
Black Hole and Time Relation
Black holes are stranger than just swallowing light. In contrast to time far from a black hole, time moves more slowly as you approach closer to one.
According to Einstein’s theory, this effect is produced by any big body, including the Earth. Although the impact of time slowing has been observed and validated by sensitive devices, the time dilation is rarely noticeable as Earth’s gravity is weak.
For example, if you lived on Mount Everest’s summit, you would age a billionth of a second more quickly than you would at sea level.
The tremendous slowing of time is found close to a black hole. Time is stopped from the perspective of an observer outside the black hole. The border of the hole, for instance, would seem to be frozen in time as an object fell into it.
Black Holes as a Time Machine
If you understand the above theory, then you might have realised that time is relative. Time and space are entangled; therefore, when a heavy object is placed in the space-time fabric, time is warped along with space.
A clock will run more slowly when it is close to a large item than when it is next to a smaller, much less substantial object.
In comparison to a clock on Earth, one located close to a black hole will tick incredibly slowly. If you leave Earth and travel near a black hole, time will pass considerably more slowly for you than it does for individuals on Earth. This means that you will age far more slowly than those on Earth.
Accordingly, your one hour spent close to a black hole could be equivalent to years spent on Earth, and when you go back to Earth, you will actually see the future because, according to you, only one hour has passed; boom! Time travel!
In this manner, time travel through black holes is possible. Simply fly close to a black hole, jump into the future, and then come back to Earth.
This was all about how you can possibly time travel in future, but can we travel in past? Things start to get really intriguing at this point. Time can wrap around itself in a black hole because of how much it is bent.
Take a piece of paper and imagine linking the two ends to create a loop. That is what it appears that a black hole does to time.
Thus, a natural time machine is produced. You would be on a trajectory through space that begins in the future and finishes in the past if you could somehow get onto the loop, which physicists refer to as a closed time-like curve.
You’d also notice that cause and effect become more intricate within the loop. Events from the past trigger occurrences in the future, which cause occurrences from the past.
The problem
To actually ‘time travel’, one might have to cross the event horizon to get into the loop. This implies that in order to leave the loop at a specific point in the past, you would have to come out of the event horizon. That means travelling faster than light, which scientists are pretty sure is impossible.
Secondly, you would undergo “spaghettification”. As you cross the event horizon, you will be stretched flat, like spaghetti. In fact, you would likely be strained to the point where all that remained of you will be a spiraling thread of atoms.
There is a difference between theory and practical; to tap such technology (time machine), more studies and research is necessary. After all, the reality is far more fictitious than fiction.
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