*Time Reborn*by Lee Smolin. The remainder of the book is kind of a grab bag of possibilities. They all point toward the reality of time, but in a variety of sometimes questionable ways.

#### Chapter 13

Smolin asks, am I committing the same cosmological fallacy I warned against before in extending quantum mechanics and the free will theorem to the entire universe? Maybe. It requires a preferred version of motion and rest that we haven't believed in since Galileo, and includes hidden variables--namely all systems of a certain type mimic each other over vast distances and faster than the speed of light. So extending the Free Will Theorem to everything, while perhaps necessary to avoid something like the Many Worlds Interpretation of quantum mechanics (which introduces vast numbers of unobservable universes), may involve a fallacy.This was a confusing chapter. I'm still not sure I get it. I think he's saying, "I don't think I've committed the same fallacy I've accused everyone else of, but it's going to be a bit tricky to argue my way out of the corner on this."

#### Chapter 14

The hidden variables required to extend Quantum Mechanics (while remaining within our observable universe) may be that space is relational and higher dimensional than 3.#### Chapter 15

Exact theories for this kind of space are several, varied, and incomplete, but that is at least hopeful for the reality of time. Space then emerges from relationships in time in several models. Ass the closest to working models require that time is universal and space is illusory. If relationships are real, turning on connections (making relationships) between particles allows faster than light communication (because lightspeed is emergent with space, not fundamental) so a being that could turn on non-local connections could act at immense distances instantly. (This would require a lot of energy in some of these theories.)This chapter essentially proposes that the choices fundamental particles make are to mimic each other (and maybe to be in relationships with each other). That's all it takes for universes to eventually emerge. This gives form to my speculation that the entire universe chose to be. What it chose was to relate and mimic. The inevitable result was continually evolving, higher order structures. I'm not sure the precedence principle will ever be provable, but I honestly can't think of any two simpler choices that could be ascribed to particles than, "will I relate with another particle?" and "will I copy or be contrary to another particle?" And at first glance, choosing to not relate or choosing to be contrary will not result in any higher order structures with the power to evolve.

#### Chapter 16

Accepting time as real resolves a bunch of anomalies that result from believing time is emergent. The biggest one is all the ways in which we observe time to have a direction--and there are a bunch of them. We can't explain the arrow in the emergent time frameworks, since laws are the same backward and forward.In the time-bound picture I propose, the universe is a process for breeding novel phenomena and states of organization, which will forever renew itself as it evolves to states of ever higher complexity and organization."Smolin proposes the principle of precedence. Sufficiently similar objects in nature imitate each other (and the choices made by other sufficiently similar objects in the past). Stuff that chooses to copy similar stuff self-organizes into more complex structures. This view makes the kind of self-organizing universe we observe a natural outcome, while the time symmetric laws suggest our universe is highly improbable--depending on very finely tuned laws and very carefully chosen initial conditions, without any reason put forward to choose the particular set we have.

#### Chapter 17

Driven self-organization is natural in a time is real paradigm. In a Newtonian, time is transcendent/illusory, paradigm the most natural universe is a dead equilibrium. Smolin argues this based on thermodynamics and entropy. (It was familiar and boring, so while I like the conclusion, I forgot to take notes.)#### Chapter 18

Infinite space with laws just like ours results in every variation infinitely many times. Smolin doesn't like it. I find it intellectually uninteresting, because it results in a form of strict determinism. It also creates the "measure problem" that Smolin thinks is unsolvable. Namely, how can you tell the difference between two completely identical universes that are bound to exist in this scenario? This scenario requires that indiscernably different objects are nonetheless different--despite its being impossible to tell them apart.Instead, Smolin prefers that quantum mechanics shows our observable universe to be finite and unique. There are at least three scientific theory reasons to prefer a finite, unbounded universe to a spacially infinite universe. The list is a summary of some technically subtle arguments that I don't pretend to have a complete grasp of.

- Only in sequential big bangs are any testable predictions about the universe made, whether it's branching or bouncing or both. "Simultaneous [and unconnected] pluralit[ies] of worlds . . . do not, and most likely cannot, make any real predictions."
- "Those burdened by the metaphysical presupposition that the purpose of science is to discover timeless truths represented by timeless mathematical objects might think that eliminating time, and so making the universe akin to a mathematical object, is a route to a scientific cosmology. But it turns out to be the opposite. As Charles Sanders Pierce understood more than a century ago, laws must evolve to be explained.

#### Chapter 19

If laws evolve, what governs that evolution? Are there meta-laws that satisfy the criterion of sufficient reason? (i.e., we can explain "why these meta-laws and not others?") Cosmological natural selection pushes that question back at least as far as the first universe. The principle of precedence maybe pushes it back even farther.I'm not hopeful that Smolin's to be completed technical book will succeed in solving what he calls the meta-law dilemma. I think believing it will may be succumbing to the fallacy he has railed against that there are transcendent laws. I suspect there will always be a real point at which some things just are, without explanation. However, I'm all for pushing as far as we can toward finding that point. I think any time we claim we've found it, we are likely wrong and limiting our own progress.

So one of the most important lessons that follow once we grasp the reality of time is that nature cannot be captured in any single logical or mathematical system. The universe simply is--or better yet, happens. It is unique. It happens once, as does each event--each unique event--that nature comprises. Why it is, why there is something rather than nothing, is probably not a question that has an answer--save that, perhaps, to exist is to be in relation to other things that exist and the universe is simply the set of all those relations. The universe itself has no relation to anything outside it. The question of why it exists rather than not is beyond the scope of the principle of sufficient reason.I'll end this post with Smolin's summary table of the things we choose between as we decide whether time is real or an illusion.

Time is an illusion. Truth and reality are timeless. |
Time is the most real aspect of our perception of the world.
Everything that is true and real is such in a moment that is one
of a succession of moments. |

Space and geometry are real. |
Space is emergent and approximate. |

Laws of nature are timeless and inexplicable, apart from
selection by the anthropic principle. |
Laws of nature evolve in time and may be explained by their
history. |

The future is determined by the laws of physics acting on the
initial conditions of the universe. |
The future is not totally predictable, hence partly open. |

The history of the universe is, in all its aspects, identical
to some mathematical object. |
Many regularities in nature can be modeled by mathematical
theories. But not every property of nature has a mirror in
mathematics. |

The universe is spatially infinite. Probabilistic predictions
are problematic, because they come down to taking the ratio of two
infinite quantities. |
The universe is spatially finite. Probabilities are ordinary
relative frequencies. |

The initial singularity is the beginning of time (when time is
defined at all) and is inexplicable. |
The Big Bang is actually a bounce which is to be explained by
the history of the universe before it. |

Our observable universe is one of an infinite collection of
simultaneously existing but unobservable universes. |
Our universe is a stage in a succession of eras of the
universe. Fossils, or remnants, of previous eras may be observed
in cosmological data. |

Equilibrium is the natural state and inevitable fate of the
universe. |
Only small subsystems of our universe come to uniform
equilibria; gravitationally bound systems evolve to heterogeneous
structured configurations. |

The observed complexity and order of the universe is a random
accident due to a rare statistical fluctuation. |
The universe naturally self-organizes to increasing levels of
complexity, driven by gravitation. |

Quantum mechanics is the final theory and the right
interpretation is that there are an infinity of actually existing
alternative histories. |
Quantum mechanics is an approximation of an unknown
cosmological theory. |

## No comments:

## Post a Comment