In science fiction, black holes have been many things- they’ve been an object of fascinaton, wonder, the edge of the unknown which has excited scientists ever since they came to know of its origin. The most notably recent introduction of black holes in pop culture was in Interstellar (2014), where the black hole Gargantua was utilized as a portal through the dimension of time. Before I move on here, I’d just like to point out the fact that, for the seemingly little that humanity knew about black holes, it was quite a realistic rendering of an actual black hole and its behaviour. This was all thanks to the assistant physicist on set, Kip S Thorne (who actually went on to share a quarter of the 2018 Nobel Prize in Physics). Each frame of the black hole seen in the film took 100 hours to render and if you see the comparison to the first relatively clear picture of a black hole captured in 2019, I’d say it is reasonably realistic.
Although the visuals were pretty realistic, the concept of time travel through a black hole is debatable. Movie fan theories talk of 5th dimensional beings and the concept of time as a 4th dimension
Researchers say that this is what information experiences after travelling through a black hole. And that’s just one of the many theories associated with it- outlined most clearly in Hawking’s Black Hole Information Paradox, given by Mr. Stephen Hawking. In 1991, Hawking and Kip S Thorne (yes, the same Kip S Thorne) wagered that information that falls into a black hole gets destroyed and can never be retrieved. This prospect followed from Hawking’s landmark 1974 discovery about black holes — regions of inescapable gravity, where space-time curves steeply toward a central point known as the singularity.
Quantum uncertainty causes black holes to radiate a small amount of heat, dubbed “Hawking radiation.” They lose mass in the process and ultimately evaporate away. This evaporation leads to a paradox: Anything that falls into a black hole will seemingly be lost forever, violating “unitarity” — a central principle of quantum mechanics that says the present always preserves information about the past.
Another alternative theory that had been placed forward is that, in principle, any Hawking radiations or other radiations emitted by a black hole would be too scrambled and volatile for us to receive any useful information from it. Alternatively, even if information somehow escapes black holes, the theory of complete quantum gravity would have to be understood to allow this to gain some credibility.
Other postulates that arise are the Firewall theories, Einstein’s equivalence principle as well as the theory of unitarity, which is explained above.
Ultimately, the theory of Hawking radiation found somewhat conclusive evidence in string theorist Samir Mathur’s research at the Ohio State University raising issues of black hole “fuzzballs” which appear to be packed full of strings, having a definitive surface like a planet or a star. They also emit heat in the form of radiation. The spectrum of that radiation, Mathur found, exactly matches the prediction for Hawking radiation.
Hawking also made his opinion on the Firewall theory public through a relatively self-explanatory two-page article posted on the Cornell University archive where he equated the Firewall Theory to weather forecasting and suggested the notion of an apparent horizon instead of an event horizon. Information could escape in such a scrambled manner after being confined behind the apparent horizon, that it may never be able to be interpreted. This also falls in line with the theory of Hawking Radiations.
The sad part is that, when we touch the edge of the unknown, the existent variables mean that seemingly practical evidence need to be tested under rigorous conditions for them to provide conclusive proof.
Stephen Hawking may not have gotten a Nobel for his theory of the Black Hole Information Paradox and Hawking Radiation, but I believe that the science we have is slowly catching up to his thoughts and hopefully, in memory of him, soon we’ll be able to translate that into practicality.
Additional Links
https://arxiv.org/abs/1401.5761 - Hawking’s paper explaining his views on the Firewall Theory.
https://www.quantamagazine.org/stephen-hawkings-black-hole-paradox-keeps-physicists-puzzled-20180314/#:~:text=Called%20the%20black%20hole%20information,holes%20are%20not%20truly%20black.
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