David Deutsch’s The Fabric of Reality came recommended as a must-read. I’ll agree that it’s a worthy read, but all you really need is this:
Reality is increasingly comprehensible and we blaze new trails of knowledge via suppositions that stick, because they have good arguments to support them that withstand criticism. Better arguments explain more with fewer conditions.
I’m paraphrasing Deutsch here, and I do agree with him. I would say further that truth-apt suppositions have innate cross-domain compatibility inasmuch as they accurately reflect something of the underlying fundamental reality, although this is already covered by “better arguments explain more”.
Spoiler alert, despite its ambitious title, the book leaves some unanswered questions, such as:
– Why is there anything?
– Why am I on the Will Show and he’s on the David Show?
One thing I really appreciate about this book is that Deutsch is aware of the limitations of purely logical justification. Although logic is an extremely powerful tool, and getting better at math got me a lot better at it, I eventually happened upon Münchhausen’s Trilemma, which demonstrates that ultimate logical justification is futile. That is, there is no way that pure logic can “defeat”, e.g., solipsism. I would say, and would still stay, that we have to take little leaps of faith, in this light.
But beyond this Deutsch, drawing upon Karl Popper and others, gives a more satisfying, thorough treatment of the development of knowledge that can be said to be knowledge. New theories spring from creative minds that tackle problems. Criticism and scientific experiments serve as a filter for the theories. Doubtless problems will be left unsolved. Repeat ad infinitum.
He also turns solipsism on its head, relying on the phenomenology that unless you’re much less sensate than Helen Keller, there’s going to be a lot more to what you perceive than your self proper:
“The solipsist, who believes that nothing exists other than the contents of one mind, must also believe that that mind is a phenomenon of greater multiplicity than is normally supposed. It contains other-people-like thoughts, planet-like thoughts and laws-of-physics like thoughts. These thoughts are real. They develop in a complex way (or pretend to), and they have enough autonomy to surprise, disappoint, enlighten or thwart that other class of thoughts which call themselves ‘I’. Thus the solipsist’s explanation of the world is in terms of interacting thoughts rather than interacting objects. But those thoughts are real, and interact according to the same rules that the realist says govern the interaction of objects. Thus solipsism, far from being a world-view stripped to its essentials, is actually just realism disguised and weighed down by additional unnecessary assumptions [such as an “outer part of myself”] – worthless baggage, introduced only to be explained away.”
There’s a lot of detail in this book, which I won’t even try to skim over, but I would draw attention to an interesting bit where the author’s self-insert debates someone who asserts that the author, uniquely, will float instead of falling, should he step off of the deck of the tower they’re standing on. Without performing an experiment that would probably not make it past the ethics committee stage, they talk about why there doesn’t even really need to be an experiment. Arguments are enough, including “Why should all objects and people fall, except David, who floats?” It’s a theory that only introduces a new problem, which itself wouldn’t be a deal-breaker for a theory if it makes some credible, reasonable attempt to address this new problem, but it doesn’t do that either.
You’ve probably heard of quantum mechanics. Careful experiments with light show that there is more going on than meets the eye or detector, that there are shadow photons that take the routes the real ones happened to not do, and they all interfere with each other. Deutsch is all-in on the many-universes implication of this kind of quantum phenomenon. He also reframes chaos theory: it’s not so much that there’s super sensitive dependence on initial conditions that a butterfly wing flap causes a hurricane later on, but rather that the quantum systems that form reality are unpredictable (at least classically). Quantum computers may one day become a game-changer beyond just making factorisation of large numbers trivial by dint of their insane innate parallelism, and in addition to destroying the security of classical cryptography, they offer the potential of perfectly secure and eavesdropper-proofed quantum cryptography.
The fact that quantum processes occur at the fundament means that when replaying the universe from its initial conditions exactly, you still would never hit the same universe twice. A perfect classical determinism just doesn’t exist.
(At least, if you’re reading this, you can at least rest assured that your particular universe has the universe that I typed these words in as an antecedent.)
Deutsch has an interesting treatment of time-travel, and the implications of a really good virtual-reality environment that includes subjective time travel, both with and without the ability to interact with the “past”. In his view, time travel to the past requires a device that actually exists in the past (at least this could help explain why we seemingly aren’t yet being visited upon by hordes of time tourists), and also that you won’t be on track to enter the same future from which you left. (One-way future-directed time-travel, and travel in a reasonable time to anywhere at all in at least the observable universe, is as “simple” as travelling really really really close to the speed of light, and so it gets a mention not much longer than this sentence.)
Deutsch does take us back to the time of Galileo, where people didn’t (openly) believe the explanation of heliocentrism yet used heliocentric models for their improved and/or simplified observational-computational concordance: you just weren’t allowed to actually assert something contrary to dogma. Similarly, many people don’t believe the many universe explanation of quantum phenomena, yet still use the models to make predictions.
Near the end of the book, he brings up the Omega Point Theory, first conceptualised by the Jesuit priest Pierre Teilhard de Chardin, and revisited by mathematical physicist Frank Tipler. Correct me if I’m wrong, but I got the impression that Deutsch is basically saying the Turing Principle around the practically limitless limits of what can be computed (I may be oversimplifying) implies a Big Crunch universe.
Like, talk about the tail wagging the dog.
First off, the observations of Hubble (meaning the man) and others strongly suggest that the expansion of our universe is accelerating, so we’re headed more towards a Big Rip (but we might get away with “just” a dark and lonely heat death rather than particles themselves being ripped apart) than a Big Crunch.
And just because you can’t build a theoretical universal computer, it doesn’t mean it’s physically impossible in and of itself, it’s just that it is something that would never be instantiated in any universe. There’s no cosmic requirement that all theoretically possible things must ultimately find instantiation.
For example, it is physically possible for simians pounding keys randomly to punch out the odd coherent word in some language, and if they can be good Calvinists and sit down to work at it, it is theoretically possible / not physically impossible for them to punch out a complete Shakespearian sonnet or even his complete works. Would that ever actually happen?1Wire-heading chimps to do it anyway should probably also be vetoed by the ethics committee IDGAFISI: No! And while I can’t give some reductive, analytic proof that it could never happen, I can instead point to common sense, and I will assert that in this particular case, our intuition is likely to be true.
Still, the Omega Point idea is interesting as a thought experiment, even if the concept first came out of Judaeo-Christianism. The final moments of a contracting universe would be, for a sufficiently advanced intelligence, an opportunity to harness unbelievable amounts of energy. While corporeally instantiated meatwalkers are not likely to fare well here, for a machine intelligence the subjective time-to-experience available would increase as the available energy increases, although during that time you also have to find a way to shore up your habitation for the increased challenges of the next microsecond. You could have a situation where “‘life’ at the asymptote” goes on indefinitely.
Deutsch doesn’t talk about this himself, and I don’t remember where I heard about this myself, but you could also have something sort of like this for a heat-dead universe, based on a pre-gathered finite source of energy, if you could just have an alarm clock that uses no energy and never breaks. Basically you just increase the sleep periods between wake periods, and keep on increasing them. Maybe eventually trillions of years of cold dead space pass in silence between each second of uptime. But there would be no continuous expansion of capabilities in this scenario, and were I a disembodied intelligence I might actually prefer the option of Dancing with the Crunch.
As far as we know, eventually new stars will stop being born, and those stars, like all the stars before them, will blow up or just puff up then meekly die out. So in the big picture it’s not just enjoy your life while you’re living it, but also enjoy the brief window in the early history of the universe when true life is possible at all!
And on that cheery note, I’ll see you next missive.