Far out cosmology: data overload (Introduction)

by David Turell , Friday, June 18, 2021, 23:18 (1252 days ago) @ David Turell

A weird review of a book:

https://www.realclearscience.com/2021/06/18/is_the_universe_open-ended_781996.html?utm_...

"Every equation of physics or every computer simulation of how planets, stars, and galaxies orbit and evolve, is a bizarre imprint of an interpretation of the universe by the universe, built into the universe by the rearrangement of its atoms into a dataome. But there’s an even deeper perspective: Was all of this really inevitable? Did we ever have a choice in creating a dataome or doing any of the things we do, and does any self-aware entity in the universe have a choice either?

"In a wonderfully lively, and extraordinarily ideas-dense, near 70-page long 2013 essay titled “The Ghost in the Quantum Turing Machine,” the theoretical computer scientist Scott Aaronson goes deep in search of arguments for and against such free will. It’s such fun that I want to spend some time with it here. He points out that many of us conflate the idea of random unpredictability with free will. For example, I can feel like I’m exerting free will if I, well, I don’t know, spontaneously write the word “sponge” here. It certainly seems entirely random.

"That, Aaronson argues, is probably not right because what we call randomness actually follows well-defined statistical rules of probability, and in that sense is never “free.” Its unpredictability is predictable. By contrast there is a class of unpredictable phenomena that can’t be measured by random probabilities; they have a different form of unpredictability. This is described by a property called Knightian uncertainty after one Frank Knight, an economist working on these ideas in the 1920s. In modern vernacular this is very much like the “black swan event” idea popularized skillfully by the writer and mathematical thinker Nassim Taleb.

***

"...the knowable universe is big but decidedly finite. We can only ever observe the realm of the cosmos from which light has had time to reach us since the Big Bang some 13.8 billion years ago. This is tricky, but we can actually estimate the maximum number of any kind of bits (not just freebits) in the observable universe as approximately ten-to-the-power-of-122 (or 10122). The implication is that this is the limit of the number of interesting things that can ever happen in the universe. No do-overs, no extras, this is it.

"But this also means that freebits, and bits, are getting “used up” over time. Indeed, they must be for events to occur. And this brings us full-circle back to the classical physics ideas of the laws of thermodynamics and entropy, and the Landauer limit on energy needed to erase bits. Storing and accessing information means using energy. But if you use energy you have to maintain or increase the entropy of the cosmos (generally speaking). If there are a finite number of bits in all of reality, even if a huge number like 10122, then eventually the universe runs out of ways to change its entropy, and its bits.

"At this point the story connects to the far, far, far cosmic future in which everything is in thermal equilibrium: Space is at the same temperature, everywhere. There are no hot and cold spots, no ways for energy to flow from warm things to chilly things. No more bits to flip and the universe ends up as a tepid bath, full of nothing but regrets. (Although regrets imply information, and there would be no way to access that at this late stage).

"Is any of this a valid description of the world that has been and is to come? We don’t really know, although our best bet is that the ever-expanding universe is indeed heading to eventual boredom in thermal uniformity. Concepts like freebits are, for now, merely intriguing proposals about what makes reality tick under the surface.

"The essential point to all of this is that information shows itself to be more than one might expect. It isn’t just a way to probe the fundamentals of nature; it may be part of the fundamentals. Consequently, the fact that the human dataome is becoming increasingly entwined with the fabric of the universe—as pieces of manipulated matter and energy—means that we (as living things) are fully committed to the universal drive toward that future ocean of unchanging, equilibrated spacetime. It is as if we popped out of the vacuum as a temporary fluctuation of energy, and we’ve been clawing our way back ever since.

Comment: I've skipped lots of confusing points. The focus is that we are filling the universe with information, and the universe is based on information.