Friday, June 15, 2018

Friday Science: Hawking 8 (Universe Origins)

Friday reviews of Stephen Hawking's A Brief History of Time so far.
Chapter 1: Heliocentric
Chapter 2: Spacetime
Chapter 3: Expansion of the Universe
Chapter 4: Uncertainty Principle
Chapter 5: Elementary Particles and the Forces of Nature
Chapter 6: Black Holes
Chapter 7: Black Holes Ain't So Black

Chapter 8: The Origin and Fate of the Universe
Here are some points of interest in this chapter:
  • Hawking presented a paper at the Vatican in 1981 apparently arguing that the universe was finite but had no boundary, meaning no beginning.
  • He recounts the path I've been trodding a lot lately. The universe started at a point, virtually infinitely hot. Then it cooled a little to where there were mostly electrons, photons, and neutrinos. About a hundred seconds protons and neutrons would start binding into deuterium and helium...
  • George Gamow suggested in 1948 that we should be able to detect background radiation from this beginning. This was discovered in 1965.
  • Then he builds to Alan Guth's idea of inflation. Why is the universe so uniform, but with significant fluctuations?
  • He mentions two versions of the anthropic principle. He does not like the strong one, although I find it hard to distinguish the two versions. What he calls the strong one basically argues that the universe is the way we see it because otherwise we would not be here. The weak one seems more to say that in a universe there is bound to be life developing somewhere.
  • He gets to Guth and inflation. In the hottest time of the universe, all the forces would have coalesced into a grand unification. Then gravity would separate out, then the strong force, then the weak force leaving the electromagnetic force working.
  • He shares a little about some papers in Moscow. He's reminiscing. Aww.
  • He ends the chapter with some suggestions toward a grand unified theory. This was in the late eighties so I'm not sure how helpful they are. Mainly, they have to do with imaginary time. I don't know enough to follow completely.
  • "If Euclidean space-time stretches back to infinite imaginary time... One could say, 'The boundary condition of the universe is that it has no boundary' It would neither be created nor destroyed" (136).
  • Hawking suggests that the imaginary time may actually be the real time. He suggests that while this universe looks like it had a beginning and will have an end, maybe this is an illusion. 
  • Of course he ends the chapter asking then why we would need God.
  • He seems to look to a big crunch. He was wrong.

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