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Monday, November 12, 2018

Review: The Universe from Nothing

The Universe from Nothing is a cosmology book written by a physicst/scientist/cosmologist. Lawrence Krauss says it started as a lecture that went viral on YouTube. The topic is of course, where did the Universe come from? What do we know about how it formed, and what the future of our visible universe is.

To explain all this in a 5 hour narration is a massive challenge, since the topics involved are difficult, encompassing quantum mechanics, relativity, and speculation about the nature of vacuum energy. What I liked about the exposition is that the concepts are introduced via experiments and empirical results, not just theory. Some of the history of the science concepts are provided (including the exposition on the Cosmic Background Radiation) but much of the history is just mentioned in passing.

The evidence for the Big Bang Theory is provided, as is the evidence (which I was not aware of) that we live in a flat universe. What's interesting is that in addition to being flat, the universe is expanding, and the stuff that's furthest away is expanding at an accelerating rate (from our perspective). The ultimate implication is that eventually those distant galaxies are going to disappear from our light-cone horizon, and we're not going to be able to be able to observe or detect their presence at all! (The timeline for this is about a trillion years, so the sun will be long gone before then, as will the Earth)

Krauss points out that in that far future timeline, astronomers and cosmologies will not be able to detect inflation (if you don't have a reference point because you can't see outside your local group, you can't detect that inflation is happening), which also means that evidence of a Big Bang would also have been erased!

OK, so much for the future of the universe. What about the past? The problem here is that we don't have a theory of quantum gravity, but the idea here is that in a vacuum, virtual particles can be created and destroyed at quantum time. My understanding of Krauss' explanation is that it is possible for space to be created at this level (which is how our Universe is expanding), but also for a whole universe to arise from vacuum as well! He never comes right out and say this, because as stated we don't really have a quantum theory of gravity that can provide a basis for such speculation. In any case, this is still an unsolved problem in physics, but at least we know that the Big Bang happened and that inflation is real.

I learned quite a bit from listening to the audio book. It's suitable even for non-technical audiences (or someone who flunked Physics like me), so I'd recommend listening to it if you're interested in the latest developments in cosmology.

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