I've always enjoyed reading Rudy Rucker even when I don't entirely agree with him. He says " "if everything happens then nothing matters", is my own problem with Everett’s multiverse! Or even, if everything happens, then nothing happens'', and in a way it's true that nothing happens if you sum everything up, but that doesn't mean nothing matters because we don't have the ability to sum everything up, the only one that could do that even in principle is somebody standing outside the Multiverse but there is nobody there, everything is in the Multiverse. If you sum up all the electrical charges in a water molecule you get zero but the various parts of the molecule do NOT have the ability to sum everything up, so some parts have a positive charge and some have a negative, and that matters, it's the reason water is a liquid at room temperature and pressure and not a gas. It is the reason life can exist.

You say "Gödel found solutions of Einstein’s equations with closed timelike curves" and that's true but those solutions are only relevant in a universe that is rotating, and observations have determined that is not the universe we live in.

Perhaps only some particular sideways worlds (as opposed to all mathematically possible Everett’s worlds) are real. See for example Robin Hanson’s speculations on “mangled worlds,” also cited in Wallace’s book. Wallace is open to the possibility that decoherence studies could reveal that this is the case even within our current understanding of quantum mechanics. And of course our understanding of quantum mechanics could change. For example, the idea that probability could be quantized (many things are quantized, so why not probability), which has been proposed but never taken too seriously, would lead to something like Robin’s ideas (high probability worlds absorb low probability ones).

<[Gôdel’s] solutions are only relevant in a universe that is rotating, and observations have determined that is not the universe we live in.>

But the existence of these solutions indicates that not all solutions of Einstein’s equations are globally hyperbolic spacetimes that can be sliced up in spacelike surfaces stacked in time, with earlier times causing later times. So Einstein’s equations suggest global determinism rather than determinism in the conventional sense of past-causes-future.

I wish to thank Rudy for this most interesting exchange. I have some comments of course, and I will write them down. But here are some quick and dirty comments:

Weaker versions of determinism and free will can be totally compatible with each other. Global determinism is not necessarily local in time if spacetime is determined but not globally hyperbolic. For example Gödel found solutions of Einstein’s equations with closed timelike curves. These spacetimes are deterministic (there’s one and only one solution) but not sliceable up in a way that is locally deterministic in time (past causes future). If so I'm still determined by the whole universe but I’m not uniquely determined by the past of the universe without me. Then I can think that I am an integral part of the cosmic feedback loop, and this is a kind of free will - the universe without me wouldn’t be the same universe, and therefore I’m part of whatever makes choices. Then I find determinism emotionally acceptable. See my chat with Emily Adlam: https://www.turingchurch.com/p/podcast-a-conversation-with-emily

That “if everything happens, then nothing matters” is also my own problem with Everett’s multiverse! Or even, if everything happens, then nothing happens. But perhaps only some particular sideways worlds (as opposed to all mathematically possible Everett’s worlds) are real? Phil Dick thought so. See my chat with Rizwan Virk: https://www.turingchurch.com/p/podcast-a-conversation-with-rizwan

Sideways realities open the door to nice concepts of life after death. If there are sideways realities, Sylvia is in all realities where she is alive, and you are with her in many/most of them.

I've always enjoyed reading Rudy Rucker even when I don't entirely agree with him. He says " "if everything happens then nothing matters", is my own problem with Everett’s multiverse! Or even, if everything happens, then nothing happens'', and in a way it's true that nothing happens if you sum everything up, but that doesn't mean nothing matters because we don't have the ability to sum everything up, the only one that could do that even in principle is somebody standing outside the Multiverse but there is nobody there, everything is in the Multiverse. If you sum up all the electrical charges in a water molecule you get zero but the various parts of the molecule do NOT have the ability to sum everything up, so some parts have a positive charge and some have a negative, and that matters, it's the reason water is a liquid at room temperature and pressure and not a gas. It is the reason life can exist.

You say "Gödel found solutions of Einstein’s equations with closed timelike curves" and that's true but those solutions are only relevant in a universe that is rotating, and observations have determined that is not the universe we live in.

John K Clark

Hi John,

Perhaps only some particular sideways worlds (as opposed to all mathematically possible Everett’s worlds) are real. See for example Robin Hanson’s speculations on “mangled worlds,” also cited in Wallace’s book. Wallace is open to the possibility that decoherence studies could reveal that this is the case even within our current understanding of quantum mechanics. And of course our understanding of quantum mechanics could change. For example, the idea that probability could be quantized (many things are quantized, so why not probability), which has been proposed but never taken too seriously, would lead to something like Robin’s ideas (high probability worlds absorb low probability ones).

<[Gôdel’s] solutions are only relevant in a universe that is rotating, and observations have determined that is not the universe we live in.>

But the existence of these solutions indicates that not all solutions of Einstein’s equations are globally hyperbolic spacetimes that can be sliced up in spacelike surfaces stacked in time, with earlier times causing later times. So Einstein’s equations suggest global determinism rather than determinism in the conventional sense of past-causes-future.

I wish to thank Rudy for this most interesting exchange. I have some comments of course, and I will write them down. But here are some quick and dirty comments:

Weaker versions of determinism and free will can be totally compatible with each other. Global determinism is not necessarily local in time if spacetime is determined but not globally hyperbolic. For example Gödel found solutions of Einstein’s equations with closed timelike curves. These spacetimes are deterministic (there’s one and only one solution) but not sliceable up in a way that is locally deterministic in time (past causes future). If so I'm still determined by the whole universe but I’m not uniquely determined by the past of the universe without me. Then I can think that I am an integral part of the cosmic feedback loop, and this is a kind of free will - the universe without me wouldn’t be the same universe, and therefore I’m part of whatever makes choices. Then I find determinism emotionally acceptable. See my chat with Emily Adlam: https://www.turingchurch.com/p/podcast-a-conversation-with-emily

That “if everything happens, then nothing matters” is also my own problem with Everett’s multiverse! Or even, if everything happens, then nothing happens. But perhaps only some particular sideways worlds (as opposed to all mathematically possible Everett’s worlds) are real? Phil Dick thought so. See my chat with Rizwan Virk: https://www.turingchurch.com/p/podcast-a-conversation-with-rizwan

Sideways realities open the door to nice concepts of life after death. If there are sideways realities, Sylvia is in all realities where she is alive, and you are with her in many/most of them.