Author Topic: The great American read  (Read 5061 times)

PonoBill

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Re: The great American read
« Reply #45 on: June 04, 2018, 08:00:10 AM »
I don't think anyone trying to model the structure and origin of the universe thinks that a big bounce origin answers the question "what comes before". At best it just moves the goalposts. Since time is tied so strongly with gravity it doesn't really exist prior to expansion or at least doesn't change. If there isn't a quantum limit to singularities--in other words, if the big bang started from a dimensionless point of infinite energy and mass, then time increments are infinitely small--i.e., doesn't progress. More directly, we can measure how time slows near a mass. At the event horizon of a black hole time nearly stops. This isn't some arm-waving theory, it's as solidly tested as any theory can be--we just exist where the macro properties provide our view of reality--which has little to do with "real" reality. There isn't even any reality to euclidian geometry. Mass warps space. The right angle corners you perceive on your desk are actually warped by your presence to something other than 90 degrees. We just can't detect that at our lumpy size without special experiments.

In a quantum gravity theory of the big bang, time and space don't exist at all prior to expansion since they are emergent properties of gravity. A limit to how small the singularity can be posits something existing "before" the singularity. The notion of a singularity emerging spontaneously works best with a dimensionless singularity. Ignoring all the math and theory, a dimensionless point is nothing, and we can imagine it originating from nothing. An origin with a minimum size is "something" and it's tougher to visualize it emerging from nothing.

Nothing really new in all this, just better math and more people looking at a way to reconcile relativity and quantum theory. The biggest challenge is that under relatively, points in space don't exist--the only meaning they have is as relationships of the three sets of gravitational field lines. In Quantum theory points have meaning, if only as the intersection of electromagnetic field lines. So the fundamental underpinnings are incompatible and need something external to reconcile them. Like a tuttle to plate adapter, only cosmic.
« Last Edit: June 04, 2018, 08:05:41 AM by PonoBill »
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Chan

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Re: The great American read
« Reply #46 on: May 21, 2019, 03:12:34 PM »
I'm rereading a fantastic book that probably will never make a list like this. Reality Is Not What It Seems -- Carlo Rovelli. This is the second time I've read it and I've listened to the audible version twice. After the second listening, I decided I needed to reread so important points didn't fly by while I was distracted (as if that ever happens). Highly recommended. Yeah, okay, it's about loop quantum gravity, but it's absurdly well written if a little repetitive. Poetry about physics. I realized that the repetition is intentional, aimed at taking a slightly different slice at important concepts.

Wow, I just did a google search to see what came up about this book and found that NPR did a review. It reads like a much longer version of what I just wrote. https://www.npr.org/sections/13.7/2017/02/01/512798209/reality-is-not-what-we-can-see


Just got around to reading Rovelli.  Highly recommended is an understatement.  I will likely read nothing else but Rovelli this year, or years, however long it takes.