Abstract
The Black Hole Information Paradox is one of the great unsolved problems in cosmology. Black holes devour all of the information that falls into them and all of it is stored in the singularity of the black hole. But here, the infamous Hawking radiation throws us off. Hawking radiation appears as a steady stream of particles, mostly photons, coming out of the black hole’s event horizon. It does not appear to contain any information, and is the same no matter what you throw into the black hole. This violate our laws of quantum information, stating that information cannot be created or destroyed.
Image courtesy : https://medium.com/@dilipacharya/the-famous-blackhole-information-paradox-64b500bd95e9
Black holes and the destruction of information
Black holes are the corpses of really massive stars, more than three times the mass of our Sun. They have extreme gravity, trillions of G’s (1G is equivalent to Earth’s gravity), that calling it infinite is okay, but are compacted into an infinitely dense point in spacetime. They devour all that falls into them, but all of the information is stored in it’s singularity. By information, I do not mean the properties of an object, such as its shape, size, or hardness. I mean its quantum properties, like its atoms direction, spin or electric charge. If you burn a piece of paper with some scribbling on it, the ash that is left contains all the quantum information of the original piece of paper. By analysing the quantum properties of every atom in the ash, you could, in theory, reconstruct the paper, scribbles and all. But black holes do the opposite - they take different things and make them the same. The amount of Hawking radiation coming out of a black hole is the same and does not hold any of the information of the object that was thrown in.
Image courtesy : https://www.sciencealert.com/stephen-hawking-just-published-new-solution-to-the-black-hole-information-paradox
The Information Paradox
This creates the “Black Hole Information Paradox”, which flies in the face of our theory of Quantum Mechanics, which states that information cannot be destroyed. This is a big problem in cosmology, and there are 3 possible theories about what happens to the information.
The 3 ways out
- Information is lost, irretrievably and forever. The information is destroyed after it reaches the singularity. If this is true, then we will have to start again on all of our laws of physics, throwing away a lot of good theories the have worked really well in the past.
- Information is hidden. At the end of its life, a part of the black hole may split off and form a new universe and transfer its information there, where we could never see or interact with it, but it is not lost.
- Information is safe. When an object falls into a black hole, it may be encoded on its surface – the event horizon. If this is the case, then the Hawking radiation could scan this information and zip away. But when a 3-D object is displayed on a 2-D surface, it is called a hologram. Black holes are extreme, but they are all still bound to the rules of the universe. So if a black hole can change 3-D to 2-D, it may be true for the whole universe.
Image courtesy : https://societyofmodernastronomy.wordpress.com/2015/02/23/the-universe-as-a-hologram/
References
- Why Black Holes Could Delete The Universe – The Information Paradox, Kurzgesagt – In a Nutshell, Aug 24, 2017, https://www.youtube.com/watch?v=yWO-cvGETRQ
- Hawking's black hole paradox explained, Fabio Pacucci, Oct 22, 2019, https://www.youtube.com/watch?v=r5Pcqkhmp_0
- The "Information Paradox", Amanda Peet, Apr 21, 2015, https://www.youtube.com/watch?v=Uc3hrEftlMU
- The Black Hole Information Paradox, PBS Space Time, Jun 20, 2018, https://www.youtube.com/watch?v=9XkHBmE-N34
- Black Holes Explained – From Birth to Death, Kurzgesagt – In a Nutshell, Dec 15, 2015, https://www.youtube.com/watch?v=e-P5IFTqB98
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