Black Hole Firewall

Outline

• Singularities

• Wormholes 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? What is the smallest possible BH mass? • Using general relativity, should be about a Planck mass, 2×10-5 g = 2.4×1018 GeV

• But, depending of what theory of quantum mechanics and gravity we use, the mass could be much smaller • Down to ~1000 GeV LHC

• Large Hadron Collider LHC

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

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

• But, LHC could also make micro black holes LHC

• What happens if you make a black hole? 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!

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

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 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 Quantum Information

• In quantum theory, information can never be destroyed 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 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 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 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? 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 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 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 Black Hole Firewall

• Particle can only be strongly entangled with one other particle • Shouldn’t also be able to be entangled with black hole 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

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

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 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

Singularity – Non-Rotating BH

• In a non-rotating BH, always hit the singularity Falling into a Singularity 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 Singularity – Rotating BH

• Ring singularity • Also an inner horizon where flow of space slows down to speed of light 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? Falling into a Rotating BH 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 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. See description and movies at:

• http://jila.colorado.edu/~ajsh/insidebh/ rn.html