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  • Writer's picturebruce yu

#7 A Brief History of Time - Black holes ain't so black

Updated: Jul 31, 2023

Chapter 7:

  1. 2nd law of thermodynamics

    1. If 2 black holes merged together, the area of the event horizon would be greater or equal to the sum of the areas of the event horizons of the original black holes (nondecreasing property)

    2. The area of the event horizon of a black hole is a measure of its entropy

    3. Black holes are emitting particles just like a hot body with entropy

  2. Mass/energy cycles of a black hole

    1. Energy can't be created out of nothing

    2. The closer a real particle is to a massive body, the lesser positive energy it has as it takes energy to lift it away against gravitational attraction

    3. So real particles can lose all its energy and have negative energy in a black hole

    4. The positive energy of the outgoing radiation would be balanced by a flow of negative energy particles into the black hole


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