Outline. Hawking radiation and the LHC. Black Hole Firewall. Singularities. Wormholes

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2 Outline Hawking radiation and the LHC Black Hole Firewall Singularities Wormholes

3 What happens at the end of evaporation? Eventually, energy of photon emitted would be larger than mass-energy of black hole. About a Planck mass No more radiation can be emitted? One last burst of particle and no remnant?

4 What is the smallest possible BH mass? Using general relativity, should be about a Planck mass, g = GeV But, depending of what theory of quantum mechanics and gravity we use, the mass could be much smaller Down to ~1000 GeV

5 LHC Large Hadron Collider

6 LHC Will collide particles at very high energy, trying to make new particles

7 LHC Looking for Higgs Boson Predicted to exist in 1964, possibly found in 2012

8 LHC But, LHC could also make micro black holes

9 LHC What happens if you make a black hole?

10 LHC Probably the black hole will evaporate almost immediately Black holes evaporate over time Very slow for big ones, almost instantly for small ones This would be great!

11 LHC Possible, but unlikely, that black hole won t evaporate, or at least not for a while But it will be very small and going almost the speed of light Will shoot through the Earth without hitting anything and keep going off into space Collision like this happen all the time in the atmosphere and we re still here

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14 Falling into a black hole In general relativity Nothing special about event horizon To a falling observer, horizon always appears to be below you Eventually get pulled apart by tidal forces Could be out side BH if it s small, inside if it s large

15 Falling into a black hole In general relativity If you try to orbit or hover, light coming in is blueshifted Fries you if you re too close to the horizon In free-fall, this doesn t happen Hawking radiation is blue shifted, but not enough to kill you Nothing special about the Event Horizon

16 Quantum Information In quantum theory, information can never be destroyed

17 Quantum Information In quantum theory, information can never be destroyed Classical example: If you know everything about a system, you can predict its state at any point in the future, or any point in the past

18 Quantum Information In quantum theory, information can never be destroyed In quantum theory, information is stored in waveforms of particles Particle can be partially in many states a once, and only picks one when it s measured

19 Quantum Information In quantum theory, information is stored in waveforms of particles Particle can be partially in many states a once, and only picks one when it s measured However, a pair of particles can be entangles such that when you measure 1 quantity in one, you also know the state of the other particle

20 Quantum Information Quantum information is a problem at an event horizon If particles fall into a black hole, information about their states is lost? Information is saved?

21 Quantum Information Quantum information is a problem at an event horizon If particles fall into a black hole, information about their states is lost? Information is saved? Information could be encoded Hawking radiation

22 Quantum Information Quantum information is a problem at an event horizon Information could be encoded Hawking radiation A surface (the event horizon) can store information about the quantum states inside it Similar to surface area storing entropy

23 Quantum Information Information could be encoded Hawking radiation This creates another problem Pairs of particles near horizon are entangled Radiation is also entangled with black hole

24 Black Hole Firewall Particle can only be strongly entangled with one other particle Shouldn t also be able to be entangled with black hole

25 Black Hole Firewall Possible solution: Particles break entanglment with infalling pair Energetic particles created just inside horizon Polchinski 2012 These particle will fry and tear apart anything that crosses the horizon Gives up principle of equivalence

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27 Back Hole Firewall Either: Give up principle of equivalence Allow information to be destroyed Allow black hole to preserve entanglement information until it almost evaporates

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29 Cosmic Censorship Hypohesis Singularity point at which physics breaks down (infinite density?) Every trapped surface contains a singularity Every singularity is inside a horizon no naked singularities

30 Singularity Non-Rotating BH Once something makes it into a black hole, if continues to fall towards the middle In a finite (and fairly short) time, it will reach the center At the Planck scale, our understanding of gravity breaks down

31 Singularity Non-Rotating BH Once something makes it into a black hole, if continues to fall towards the middle In a finite (and fairly short) time, it will reach the center At the Planck scale, our understanding of gravity breaks down In a non-rotating BH, always hit the singularity

32 Falling into a Singularity

33 Singularity Rotating BH Singularity has angular momentum Will form a ring singularity Possible to fall in and miss the singularity Only hit the ring if you come in in the plane of the ring, otherwise it is repulsive

34 Singularity Rotating BH Ring singularity Also an inner horizon where flow of space slows down to speed of light

35 Rotating BH Falling through inner horizon you see infinitely blueshifted light You can miss the singularity and are push back out through another horizon Black hole connects to a white hole somewhere else Another universe? Pocket universe? Another part of the same universe?

36 Falling into a Rotating BH

37 Wormhole Rotating (or charged) black hole can act as a wormhole Unstable. Will collapse if anything tries to go through it Needs to be stabalized

38 Rotating BH as Wormhole You can miss the singularity and fall back out through another horizon You can see another universe and escape through the white hole In reality, the connection will be unstable and collapse once anything ties to go through it.

39 See description and movies at: rn.html