This was a very well written discourse on the existence of different universes, and a bit of an intuition about how to think about them.<p>It reminds me a lot (though it is quite different) of "Flatland: A Romance of Many Dimensions" [0]. This book gave me the best intuition yet about what it would be like to experience a fourth spatial dimension.<p>Having said that, I still don't quite know what to think about it. I definitely don't have a mental picture of what it would be like. All I know is that when I was reading the book, I had a part of my brain clicking along, which <i>felt</i> like it understood what it is to experience an additional spatial dimension. Yet there is still very little actual comprehension going on in there.<p>[A bit of a spoiler alert follows]<p>It starts by explaining in meticulous detail what it is like to live in and experience fictional 2D world instead of the 3D one we are used to.<p>Then, the main character transcends into a 1D world. The book explains to the 2D inhabitant what it is like to live in a 1D world. Explaining this to the 2D inhabitant is the same as explaining the 2D world to us (and our 3D world).<p>Finally, the character moves up to a 3D world, which they cannot comprehend. However the explanations which are given to the character are quite intuitive and satisfying, and help to explain what it might be like for us to move up one dimension and experience it.<p>[0] - <a href="https://en.wikipedia.org/wiki/Flatland" rel="nofollow">https://en.wikipedia.org/wiki/Flatland</a><p>p.s. The book is also a hilarious parody on victorian era attitudes towards women.
Read this in the past and there's a few things that bother me<p>* It's impossible to simulate a universe of our current resolution, because it would take more matter than the original universe.<p>* You can't just simulate 'observable areas'. Everything needs to be simulated.<p>* An infinite loop does not end, even in an infinitely powerful computer<p>* A fun calculation from the ZFS folks: To fully populate a 128bit filesystem (ie permute all combinations) you a lot of energy. So much energy you could boil the world's oceans, See:<p>* [1] Physical Limits of Computation: <a href="http://arxiv.org/pdf/quant-ph/9908043.pdf" rel="nofollow">http://arxiv.org/pdf/quant-ph/9908043.pdf</a><p>* [2] <a href="https://blogs.oracle.com/dcb/entry/zfs_boils_the_ocean_consumes" rel="nofollow">https://blogs.oracle.com/dcb/entry/zfs_boils_the_ocean_consu...</a>
It bothers me that this uses "quantum computing" since it plays into common, frustrating, misapprehensions of what quantum computing is even theorized to do.<p>They could at least call it a hyper-computer or acausual timeloop processor or something.
Yes, I'm late. So what. People miss the fundamental point.<p>The characters clearly state that since their level of emulation is approaching infinity, anything they do to their child universes will simply be reflections of the parent simulations.<p>Look at it this way. You rewind to 1942. You're going to kill Hitler. But your universe simulation is so in tune to the parent universe they're already doing the same thing. What you interprets as free will is the averaged responses of all parent universes. At some point in the simulation universe 2 billion plus above you someone actually has an original though to kill Hitler. This is simply re-emulated endless times.<p>There are no original thoughts in this view of the universe.
It's very cool, I'm only a bit disappointed that the author did not consider what would happen if they tried to run the simulation ahead of them to see the future. What would happen then? All kinds of paradoxes arise.
I would post obligatory link of someone calculating expected number of universes on top of ours based on planks distance and something else, but I can't find it.<p>Instead have this simulation argument here: <a href="http://www.simulation-argument.com/" rel="nofollow">http://www.simulation-argument.com/</a>
Instead of changing things one universe below, change things 3 universes below you.<p>Or change the universe below you to change things 2 universes below it to change things in the universe 4 layers underneath that.
"What the hell am I looking at?"<p>"Now, you're looking at now, sir. What's happening now, is happening, now."<p>"What happened to then?"<p>"We passed it."<p>"When?"<p>"Just now."<p>"When will then be now?"<p>"Soon!"
There's a technical solution concept in game theory that mirrors Diane's reasoning here. I wish I could remember the name of the solution concept offhand, but the idea is that, even though your own decision won't affect the decision anyone else makes, you still make the "altruistic" decision, reasoning that the other people involved will use the same reasoning and come to the same conclusion.<p>The paradox, of course, is that, having come to that conclusion, you could just choose to make the "non-altruistic" decision. Everyone else has already decided what they're going to do, so you won't change that. Except the solution concept stipulates that they reason exactly as you do, so if you make this decision, so will they.
Great story! One thing that stuck out to me—if you had an infinitely powerful computer, the "coding" aspect of it should take no time at all. All you have to do is come up with a description language to say what you want•, and b) seed rules for a genetic programming language, and then throw it at your infinitely powerful computer. You'll get a working program instantly.<p>• This might still be significantly difficult. If only you had a simulated version of yourself that you could use as a control subject so the computer could test whether or not the generated program met your expectations...
This gives me an interesting thought, in the story all lower levels of the simulation are identical copies from the top level, in every way. The first time that they create the black ball the top level universe will diverge from the rest (they will look behind and there will be no ball) at this point there will be no more perfect copies of the original universe.<p>Also I wonder about the ethical connotations of turning off the machine as was suggested at the end. At what point is life "life". If the simulated beings are truly perfect, would turning it off be the largest genocide ever committed?
If Diane created a complete simulation and then separately created a program to observe that simulation at certain points in time, then doesn't it follow that the entire universe from Big Bang to Big Crunch was already calculated and executed?<p>In that case, turning the simulation off would do nothing from the perspective of the people within it, because every simulation has already been played out to completion. All they would be turning off is the ability to observe what the simulation looked like at specific points in time.
The problem I have with this story (and the simulation argument in general) are the dubious assumptions that simulation within which we exist, 1) is manifested in a physical reality which is functionally identical our own; and, 2) created by autonomous beings who are fundamentally like us in all important respects. More likely we would merely be the flashing cells of automata to a higher order simulation builder.
>"Can you wind the clock backwards at all?"<p>>"Ah, no. Ask me again on Monday."<p>Really? I'm just a layman but if it's a simulation, like game of life, then logic tells me that they should also be able to rewind the simulation by backstepping. Either that, or she just created magic.
So what's the difference between specifying a universe-simulating algorithm, and specifying its initial conditions, versus actually running it? Since the entire history is somehow implied in that specification, don't all those people in some sense exist?
A question (to which there is an answer), how would you find out how far down the line you are?<p>Answer: look behind you, place the value you see plus one into the next universe.
"There is a feedback loop going on. Each universe affects the next one subtly differently. But somewhere down the line the whole thing simply has to approach a point of stability"<p>Why would each universe affect the next one (subtly) differently?
Oh, and just because you have a infinitely powerful quantum computer simulating infinitely many recursive universes with their own infinitely powerful quantum computers, correlation != causation doesn't apply anymore?