Friday, October 31, 2014

Time Is Real--Part II

Continuing my summary and review of Lee Smolin's book, Time Reborn: From the Crisis in Physics to the Future of the Universe. The most amazing part, for me, of this installment is that my Lee Smolin gives form to my vague idea that creation came to be through the agency of fundamental particles. The exact choice being made is the choice to imitate other similar particles. Enough of the teaser, on to the book.

Chapter 8

We currently have many theories (infinitely many) that account for the universe we have measured, so far, so there is no answer as to "why this universe?". Also, our laws come from repeated observation, but it is not possible for us to repeatedly observe the whole universe.
1. The assertion that a law applies on a cosmological scale implies a vast amount of information about predictions concerning nonexistent cases--that is, other universes. This suggests that something much weaker than a law might explain the universe. We don't need an explanation so extravagant that it makes predictions about an infinite number of cases that never actually happen. An explanation that accounts only for what actually happens in our single universe would suffice.
2. The usual kind of law cannot explain why the solution that describes our universe is the one we experience. [There are infinitely many solutions to our current set of laws of physics. Why do we see our particular universe?]
3. The law cannot account for itself. It offers no rationale for why it, rather than some other law, holds.
So our current theories are poor candidates for complete cosmological theories because they explain what happens in universes we can't observe, and don't give sufficient reason for why we observe the one we do.

Chapter 9

The notion of an effective theory represents a maturing of the profession of elementary-particle theory. Our young, romantic selves dreamed we had the fundamental laws of nature in our hands. After working with the Standard Model for several decades, we are now simultaneously more confident that it's correct within the limited domain in which it has been tested and less confident of its extendability outside that domain. Isn't this a lot like real life? As we grow older, we gain confidence about what we really know and simultaneously find it easier to admit ignorance about what we don't.
This may seem disappointing. Physics is supposed to be about discovering the fundamental laws of nature. An effective theory is by definition not that. If you have too naive a view of science, you might think that a theory could not both agree with all experiments yet carried out and be considered at best only an approximation to the truth. The concept of an effective theory is important, because it expresses this subtle distinction.
It also exemplifies how we understand progress in elementary-particle physics. It tells us that physics is a process of constructing better and better approximate theories. . . .
The notion of an effective theory implies that progress in physics entails revolutions that completelychange the conceptual basis of our understanding of nature while preserving the successes of earlier theories. . . .
The fact is that every theory we have so far used in physics has been an effective theory. It is sobering to realize that part of the cost of their success was the realization that they are approximations.
We still may harbor the ambition to invent a fundamental theory that describes nature without approximation. Both logic and history tell us this is impossible [unless the theory encompasses the whole universe at once].
And that might not even do it.
Is Mormonism maturing?

Chapter 10

Four conditions that any theory that encompasses the entire universe at once must minimally meet:
  • Must contain all previous knowledge about nature, but as approximations.
  • Must make specific, testable predictions from doable experiments.
  • Should give a reason for "Why these laws?" and not others
  • Should answer "Why these initial conditions" and not others
Here is where Smolin distinguishes his universe/multiverse from other multiverse models (like the MWI, or Brane models). Smolin's universes must be causally connected, even if it is nearly unobservably so through black holes. So the multiverse is really a big, branching universe.

Since laws are necessarily relational, laws must evolve as relationships evolve. Big Bangs past and future must be connected. The reason our Big Bang was the way it was is because of its connection to a previous universe, and we can theoretically learn something about the previous universe.

To the four minimal requirements, Smolin adds a few more:
  • It will posit neither symmetries nor conservation laws.
  • It should be causally and explanatorily closed. Nothing outside the universe should be required to explain anything inside the universe.
  • It should satisfy the principle of sufficient reason, the principle of no unreciprocated action, and the principle of the identity of the indiscernibles.
  • Its physical variables should describe evolving relationships between dynamical entities. There should be no fixed-background structures, including fixed laws of nature. Hence the laws of nature evolve, which implies that time is real.

Chapter 11

Smolin summarizes the principles of cosmological natural selection.
Applying natural selection to a system to explain its complexity requires the following:
  •  A space for parameters that vary among a population. . .
  • A mechanism of reproduction. . .
  • Variation. . .
  • Differences in fitness. . .
  • Typicality. . . [the assumption that our own universe is typical]
The power of natural selection as a methodology is such that strong conclusions can be drawn from these minimal assumptions.
I loved this last line, since it's what I've been asserting with my exploration of the nature of God. As Smolin says about cosmological natural selection, I can say about the evolution of Gods.
. . . all that need be claimed is that our universe has only a relative fitness advantage over universes differing by small changes in the parameters. This is a very weak condition. We needn't assume that the parameters of our universe are the largest possible; there very well might be other parameter choices leading to an even more fertile universe. All the scenario predicts is that they can't be reached by making a small change from the present values.
Why doesn't God fix everything? This is already a relatively fertile universe, and He can't make more fertile universes by making drastic changes. He's stuck with it as much as we are.

Back to Smolin. The anthropic principle is just a way to end the conversation. The universe is as it is because it must be for us to be here asking these questions. With no other universes to test, we can't know if this is true. If something isn't required for our existence, we have no way to explain its having a particular property.
The fact that you can adjust unobservable features of your scenario to enable you to pick one that fits your hypothesis better does not constitute evidence for that scenario.
This is why I am attracted to the God of Mormonism that is within Nature, and not interested in Gods that are outside of or over Nature. Those Gods have adjustable parameters that can never be tested by any imaginable experiment. While I believe there are unprovable truths, I am not interested in latching on to a particular statement of what those are and basing my life decisions on it--inside or outside of Mormonism.

I did wonder at this point if some of the problems Smolin attributes to ideas he criticizes don't still apply to the first universe implied by the reality of time. I don't think so, but can't formulate it clearly. How was the first universe selected? Perhaps by picking some very basic initial conditions these problems can be minimized. For example, the stuff of the universe is eternal and without beginning or end. Discrete portions of the stuff have sufficient will to choose to mimic and associate with like particles or not mimic like particles. Still working on this, but I'm jumping ahead.

Chapter 12

Maybe natural law acts on precedent. If a system is similar enough, past precedent is followed. If a system is truly novel, then the outcome is unpredictable.
If nature is like this, then the future is genuinely open. We would still have the benefit of reliable laws in cases with ample precedent, but without the stranglehold of determinism.
It is fair to say that classical mechanics precludes the existence of genuine novelty. . .
. . . entanglement can produce genuinely novel properties.
So I was right about the problems quantum mechanics propose for determinism, but not as clear on the why as Smolin explains. Thank you Dr. Smolin.

The "principle of precedence acts in nature to ensure that the future resembles the past. This principle is sufficient to uphold determinism where it's needed but implies that nature, when faced with new properties, can evolve new laws to apply to them." [Big, relatively unique, systems, like people, are more likely to express new properties than simpler systems, but not very often. So human behavior will be mostly predictable, but not entirely.]

". . . the idea that choices atoms make are truly free (i.e., uncaused) fails to satisfy the demand for sufficient reason--for an answer to every question we might ask of nature." That's the cliff-hanger with which Smolin ends the chapter. The view he favors fails one of his tests. Next chapter he tries to say why that's ok, and I like his answer.

Enough for this post. We'll do a Part III.

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