Fragile Universe Hypothesis and the Continual Anthropic Principle - How crazy am I?
post by PeterCoin · 2015-08-18T00:53:16.711Z · LW · GW · Legacy · 32 commentsContents
Personal Statement Abstract Preliminary reasoning Will a supercollider destroy the Earth? A false application of the anthropic principle Will a supercollider destroy the universe? Quantum immortality and suicide Have supercolliders destroyed the universe? It's not a bug it's a feature! Fragile Universe Hypothesis Introduction Core theory Possible Objections "If I get destroyed I die and will no longer have experiences. This is at face value absurd" "This sort of reasoning would result in having to accept absurdities like quantum immortality" "This isn't science. What testable predictions are you making? Heck you don't even have a solid theory" Final Thoughts The Copernican Principle for Many worlds Why confine the Anthropic Principle to the past? None 32 comments
Personal Statement
I like to think about big questions from time to time. A fancy that quite possibly causes me more harm than good. Every once in a while I come up with some idea and wonder "hey, this seems pretty good, I wonder if anyone is taking it seriously?" Usually, answering that results at worst in me wasting a couple days on google and blowing $50 on amazon before I find someone who’s going down the same path and can tell myself. "Well, someone's got that covered". This particular idea is a little more stubborn and the amazon bill is starting to get a little heavy. So I cobbled together this “paper” to get this idea out there and see where it goes.
I've been quite selective here and have only submitted it on two other places Vixra, and FXQI forum. Vixra for posterity in the bizarre case that it's actually right. FXQI because they play with some similar ideas (but the forum turned out to be not really vibrant for such things). I'm now posting it on Less Wrong because you guys seem to be the right balance of badass skeptics and open minded geeks. In addition I see a lot of cool work on Anthropic Reasoning and the like so it seems to go along with your theme.
Any and all feedback is welcome, I'm a good sport!
Abstract
A popular objection to the Many-worlds interpretation of Quantum Mechanics is that it allows for quantum suicide where an experimenter creates a device that instantly kills him or leaves him be depending the output of a quantum measurement, since he has no experience of the device killing him he experiences quantum immortality. This is considered counter-intuitive and absurd. Presented here is a speculative argument that accepts counter-intuitiveness and proposes it as a new approach to physical theory without accepting some of the absurd conclusions of the thought experiment. The approach is based on the idea that the Universe is Fragile in that only a fraction of the time evolved versions retain the familiar structures of people and planets, but the fractions that do not occur are not observed. This presents to us as a skewed view of physics and only by accounting for this fact (which I propose calling the Continual Anthropic Principle) can we understand the true fundamental laws.
Preliminary reasoning
Will a supercollider destroy the Earth?
A fringe objection to the latest generation of high energy supercolliders was they might trigger some quantum event that would destroy the earth such as by turning it to strangelets (merely an example). To assuage those fears it has been noted that since Cosmic Rays have been observed with higher energies then the collisions these supercolliders produce that if a supercollider were able to create such Earth-destroying events cosmic rays would have already destroyed the Earth. Since that hasn't happened physics must not work that way and we thus must be safe.
A false application of the anthropic principle
One may try to cite the anthropic principle as an appeal against the conclusion that physics disallows Earth-destruction by said mechanism. If the Earth were converted to strangelets, there would be no observers on it. If the right sort of multiverse exists, some Earths will be lucky enough to escape this mode of destruction. Thus physics may still allow for strangelet destruction and supercolliders may still destroy the world. We can reject that objection by noting that if that were the case, it is far more probable that our planet would be alone in a sea of strangelet balls that were already converted by highenergy cosmic rays. Since we observe other worlds made of ordinary matter, we can be sure physics doesn't allow for the Earth to be converted into strange matter by interactions at Earth’s energy level.
Will a supercollider destroy the universe?
Among the ideas on how supercolliders will destroy the world there are some that destroy not just the Earth but entire universe as well. A proposed mechanism is in triggering vacuum energy to collapse to a new lower energy state. By that mechanism the destructive event spreads out from the nucleation site at the speed of light and shreds the universe to something completely unrecognizable. In the same way cosmic rays rule out an Earth-destroying event it has said that this rules out a universe destroying event.
Quantum immortality and suicide
Quantum suicide is a thought experiment there is a device that measures a random quantum event, and kills an experimenter instantly upon one outcome, and leaves him alive upon the other. If Everett multiple worlds is true, then no matter how matter how many times an experiment is performed, the experimenter will only experience the outcome where he is not killed thus experiencing subjective immortality. There are some pretty nutty ideas about the quantum suicide and immortality, and this has been used as an argument against many-worlds. I find the idea of finding oneself for example perpetually avoiding fatal accidents or living naturally well beyond any reasonable time to be mistaken (see objections). I do however think that Max Tegmark came up with a good system of rules on his "crazy" page for how it might work: http://space.mit.edu/home/tegmark/crazy.html
The rules he outlines are: "I think a successful quantum suicide experiment needs to satisfy three criteria:
1. The random number generator must be quantum, not classical (deterministic), so that you really enter a superposition of dead and alive.
2. It must kill you (at least make you unconscious) on a timescale shorter than that on which you can become aware of the outcome of the quantum coin-toss - otherwise you'll have a very unhappy version of yourself for a second or more who knows he's about to die for sure, and the whole effect gets spoiled.
3. It must be virtually certain to really kill you, not just injure you.”
Have supercolliders destroyed the universe?
Let's say that given experiment has a certain "probability" (by a probabilistic interpretation of QM) of producing said universe destructive event. This satisfies all 3 of Tegmark's conditions for a successful quantum suicide experiment. As such the experimenter might conclude that said event cannot happen. However, he would be mistaken, and a corresponding percentage of successor states would in fact be ones where the event occurred. If the rules of physics are such that an event is allowed then we have a fundamentally skewed perceptions of what physics are.
It's not a bug it's a feature!
If we presume such events could occur, we have no idea how frequent they are. There's no necessary reason why they need to be confined to rare high energy experiments and cosmic rays. Perhaps it dictates more basic and fundamental interactions. For instance certain events within an ordinary atomic nucleus could create a universe-destroying event. Even if these events occur at an astonishing rate, so long as there's a situation where the event doesn't occur (or is "undone" before the runaway effect can occur), it would not be contradictory with our observation. The presumption that these events don't occur may be preventing us from understanding a simpler law that describes physics in a certain situation in favor of more complex theories that limit behavior to that which we can observe.
Fragile Universe Hypothesis
Introduction
Because of this preliminary reasoning I am postulating what I call the "Fragile Universe Hypothesis". The core idea is that our universe is constantly being annihilated by various runaway events initiated by quantum phenomena. However, because for any such event there's always a possible path where such event does not occur, and since all possible paths are realized we are presented with an illusion of stability. What we see as persistent structures in the universe (chairs, planets, galaxies) are so only because events that destroy them by and large destroy us as well. What we may think are fundamental laws of our universe, are merely descriptions of the nature of possible futures consistent with our continued existence.
Core theory
The hypothesis can be summarized as postulating the following:
1. For a given event at Time T there are multiple largely non-interacting future successor events at T + ε (i.e. Everett Many Worlds is either correct or at least on the right track)
2. There are some events where some (but not all) successor events trigger runaway interactions that destroy the universe as we know it. Such events expand from the origin at C and immediately disrupt the consciousness of any being it encounters.
3. We experience only a subset of possible futures and thus have a skewed perspective of the laws of physics.
4. To describe the outcome of an experiment we must first calculate possible outcomes then filter out those that result in observer destruction (call it the "continual anthropic principle")
Possible Objections
"If I get destroyed I die and will no longer have experiences. This is at face value absurd"
I'm sympathetic, and I'd say this requires a stretch of imagination to consider. But do note that under this hypothesis, no one will ever have an experience that isn't followed by a successive experience (see quantum immortality for discussion of death). So from our perspective our existence will go on unimpeded. As an example, consider a video game save. The game file can be saved, copied, compressed, decompressed, moved from medium to medium (with some files being deleted after being copied to a new location). We say that the game continues so long as someone plays at least one copy of the file. Likewise for us, we say life (or the universe as we know it) goes on so long as at least one successor continues.
"This sort of reasoning would result in having to accept absurdities like quantum immortality"
I don't think so. Quantum immortality (the idea that many worlds guarantees one immortality as there will always be some future state in which one continues to exist) presumes that personhood is an all-ornothing thing. In reality a person is more of a fragmented collection of mental processes. We don't suddenly stop having experiences as we die, rather the fragments unbind, some live on in the memory of others or in those experiencing the products of our expression, while others fade out. A destructive event of the kind proposed would absolutely be an all-or-nothing affair. Either everything goes, or nothing goes.
"This isn't science. What testable predictions are you making? Heck you don't even have a solid theory"
Point taken! This is, at this point, speculation, but I think at this point it might have the sort of elegance that good theories have. The questions that I have are:
1. Has this ever been seriously considered? (I’ve done some homework but undoubtedly not enough).
2. Are there any conceptual defeaters that make this a nonstarter?
3. Could some theories be made simpler by postulating a fragile universe and continual anthropic principle?
4. Could those hypothetical theories make testable predictions?
5. Have those tests been consistent with the theory.
My objective in writing this is to provide an argument against 2, and starting to look into 1 and 3. 4 and 5 are essential to good science as well too, but we’re simply not at that point yet.
Final Thoughts
The Copernican Principle for Many worlds
When we moved the Earth as the center of the solar system, the orbits of the other planets became simpler and clearer. Perhaps physical law can be made simpler and clearer when we move the futures we will experience away from the center of possible futures. And like the solar system's habitable zone, perhaps only a small portion of futures are habitable.
Why confine the Anthropic Principle to the past?
Current models of cosmology limit the impact of the Anthropic selection on the cosmos to the past: string landscapes, bubble universes or cosmic branes, these things all got fixed at some set of values 13 billion years ago and the selection effect does no more work at the cosmic scale. Perhaps the selection effect is more fundamental then that. Could it be that instead 13 billion years ago is when the anthropic selection merely switched from being creative in sowing our cosmic seeds to conservative in allowing them to grow?
32 comments
Comments sorted by top scores.
comment by DanielLC · 2015-08-19T07:44:04.493Z · LW(p) · GW(p)
I'm pretty sure I've seen this before, with the example of our universe being a false vacuum with a short half-life.
Replies from: PeterCoin↑ comment by PeterCoin · 2015-08-19T14:03:24.153Z · LW(p) · GW(p)
I've seen a number very small mentions like that, but never anything giving it more than passing consideration. In addition, I haven't seen anyone postulate that this could be distorting our view of other physical laws.
If you've come across something more, I would love to see it!
Replies from: DanielLC↑ comment by DanielLC · 2015-08-19T17:52:56.965Z · LW(p) · GW(p)
Obviously it would distort our view of how quickly the universe decays into a true vacuum. There's also the mangled worlds idea to explain the Born rule.
Replies from: PeterCoin↑ comment by PeterCoin · 2015-08-25T04:32:23.370Z · LW(p) · GW(p)
Certainly it would do that, but that could have other effects. For instance, let's say that the presence of a magnetic monopole would rapidly nucleate a vacuum decay event which otherwise would not occur. That effect might explain why the standard model does not include magnetic monopoles.
I'll have to dig into mangled worlds, It seems pretty interesting. Will report back with results, hopefully.
comment by ThisSpaceAvailable · 2015-08-19T00:55:59.005Z · LW(p) · GW(p)
I think that the first step is to unpack "annihilate". How does one "annihilate" a universe? You seem to be equivocating between destroying a universe, and putting it in a state inhospitable to consciousness.
It also seems to me that once we bring the anthropic principle in, that leads to Boltzmann brains.
Replies from: PeterCoin↑ comment by PeterCoin · 2015-08-19T19:56:20.330Z · LW(p) · GW(p)
So yes, annihilation refers specifically to any process that would at light speed render the universe lethal to life as we know it. I think of it sort of like living on a bubble that's always bursting (in timelines we don't observe). There's something left over but it's pretty unrecognizable.
Any account of the origin of the universe is probably going to have some anthropic consideration, so Boltzmann brains are not a unique problem. But I think fragile universe hypothesis may be an asset in solving it. Conventional cosmology calls for a short lived active universe with an infinitely long lived remainant after heat death. Whereas in fragile universe that remainent dwarfed in scale by the outcomes of these shattering events which may well create intelligences that don't suffer the Boltzmann pathology.
comment by Viliam · 2016-03-24T07:43:26.423Z · LW(p) · GW(p)
If this hypothesis ("99% of universes get destroyed every microsecond, but we don't notice because of anthropic principle") would be true, the question is what exactly are those universe-destroying events, and whether something can increase or decrease their probability.
Because if the probability of the universe-destroying event depends on some factor X, then we couldn't observe the destruction of universe per se, but we could imagine statistically weird behavior of X. For example, if we flip a coin, and the outcome of head means that universe gets destroyed with 99% probability, but the outcome of tails means that universe gets destroyed with 99.9% probability, from our point of view it would seem like an imbalanced coin where the head falls about ten times more likely than tails.
Problem is, we wouldn't necessarily perceive this as "statistically weird", but rather as completely normal, because that's how it always was. From our point of view, it would be just another law of physics: "If you flip a coin, the outcome is head ten times more likely than tails; that's how the coins behave, duh".
So maybe at this moment we could start suspecting any fact about our universe, or any law of physics, as a statistical artifact of the "fragile universe hypothesis".
Something like: "Why do neutrinos have such a small mass?" "Maybe there is a reason why the mass has to be non-zero, but maybe also more massive neutrinos generate universe-destroying events more frequently, which is why we find ourselves in a universe with neutrinos having small mass."
Or: "Why is universe expanding?" "Each collision of particles has a non-zero probability of generating a universe-destroying event, and this is why we are more likely to find ourselves in a universe where the frequency of collisions is decreasing; i.e. an explanding universe."
Replies from: PeterCoin↑ comment by PeterCoin · 2016-05-24T07:01:53.677Z · LW(p) · GW(p)
This is exactly the suspicion I have. The "real" physical laws could be quite different from the "experienced" physical laws. If this idea is correct physicists are only getting a small piece of the story of how the universe really operates.
It seems to me that this sort of behavior could (with sufficient refinement) provide an account for some of the more bizarre aspects of physical law. An obvious target is the counterintuitive statistics that make quantum mechanics so spooky.
It would also be place where physicsists could stuff their physics - extra degrees of freedom to explain the regularities we observe in nature. Perhaps instead of tiny curled dimensions of string theory we can stuff some of that physics into the details of a sort of subatomic brinksmanship.
(sometimes I wonder [not too seriously] if this could explain why certain things aren't - why we don't see dark matter, or where there are no free quarks or magnetic monopoles - maybe when they crop up the world as we know it ceases to be)
A pernicious difficulty is tying our experience of probability to what is actually going on. Ultimately some sort of self-selection accounting must occur. This is where we come up against sleeping beauty type problems and need to question some strongly held intuitions.
And that's where I start getting confused (not that there aren't other confusing aspects to this)!
I generally take that confusion to be a good sign. If there wasn't some dangerous conceptual waters everyone would wade in. What I don't see any real no go as to why the universe couldn't be this way.
Replies from: Viliam↑ comment by Viliam · 2016-05-24T07:26:27.428Z · LW(p) · GW(p)
An obvious target is the counterintuitive statistics that make quantum mechanics so spooky.
Please don't go this way, this is an obvious dead end. Trying to explain something you don't understand by proposing even weirder hypothesis with completely unpredictable consequences... yeah, it's tempting, but you could equally say that "maybe magic is real... and that would explain the double-slit experiment". It kinda would, but only because it could explain literally everything.
Replies from: PeterCoin↑ comment by PeterCoin · 2016-05-29T04:56:56.017Z · LW(p) · GW(p)
I get the sort of unrestrained woolly thinking that comes from a diet of too much insight porn and an overtrusting one's own ideas. Let me assure you that I don't particularly trust my suspicion here. My aim is to see if it is a good idea or not and if it is a good idea see how far it goes. I figure if someone can provide an extremely compelling argument as to why it's not true then that itself would probably be pretty interesting!
On the subject of quantum mechanics my intent is not to explain a mystery with another mystery fill it with secret sauce and revel in the mysticism. I detest such a thing. Since my idea rests on a specific properties of the "true" interpretation of quantum mechanics (one where our experience of time branches) I sort of view partaking in that fight as a necessary endeavour.
My imediate aim is much more focused. I'm specifically referring to the counterintuitive nature of probability in situations like Bell's theorem. There is a strong link in mathematical structure between Bell's and conditional probability which has its own famous counterintuitive probability puzzle (The Monty Hall Porblem). I believe the possibility of universe destroying events can exhibit the same sort counterintuitive subjective experiences. However I have yet to really flesh it out in a more rigorous way.
I apologize if that last paragraph comes off a bit as word salad. Part of why it's hard to explain is because probability in a branching-time scenario is sort of an illusion. In MWI a quantum coin flip both heads and tails are actually observed. The perception of a 50/50 chance is "merely" a subjective experience. Which means you have to be very deliberate about what you're talking about; it gets tricky to talk clearly about it.
Anyways what excites me more is when you said "please don't go this way" you sort of imply that there's another way that you find to be better. I'd really like to know your thoughts as to where you'd like to see it go. I fully expect to go down paths where completely reasonable people will ask "what the hell is that dude thinking? and I fully expect to sometimes ask myself later "what the hell was I thinking?"
"Those are my principles, and if you don't like them... well, I have others." - Groucho Marx
Replies from: Viliam↑ comment by Viliam · 2016-05-29T19:58:05.035Z · LW(p) · GW(p)
Well, if you get some mathematics explaining why universe destruction results in exactly the numbers known from quantum physics, then maybe it gets interested.
Sorry, I have no specific path to follow, other than to first study quantum physics on its own (all the equations with the complex numbers etc.) before inventing your own theory of why it is what it is. First get to know what, then speculate about why. Otherwise you are at risk of getting quantum physics wrong, and then inventing reasons for your wrong understanding of the quantum physics, which is a lose/lose situation (either you can't find a good explanation, or you succeed to find an "explanation" for something that is actually not true). If you get familiar with the standard university-level quantum physics, then your hypotheses get the chance to be actually useful.
Making a wrong hypothesis is the inevitable risk, but seeing people waste energy inventing explanations for something that is not true, that's quite sad. (I am now thinking on one long lecture I attended at Mensa, where a guy "disproved theory of relativity" by proposing a theory that was obviously wrong for trivial reasons; it actually predicted that particles would move quite differently parallel to some absolute space axes x,y,z than diagonally. Since there are no obvious "straight" and "diagonal" directions in our universe, his hypothesis was completely wrong regardless of whether Einstein was right or wrong about some technical detail.)
Replies from: PeterCoin↑ comment by PeterCoin · 2016-08-07T06:00:27.821Z · LW(p) · GW(p)
So yeah. the gold standard is. of course. scientific prediction. My idea is very far away from such a thing! I actually do have some background in quantum mechanics (I have a physics minor :P) and at one point actually did have some understanding of Hamiltonian Operators and eigenstates and bra-ket notation. However that's a far cry from the sort of needed mathematics to really understand the implications of what I'm talking about (this is why they say a little knowledge is a dangerous thing)! What I do have is enough knowledge to tentatively pose that my idea doesn't contradict what we've actually seen in experiments (so I don't think it's trivially wrong).
I'm not too worried about proposing a possible explanation first then asking what it can explain. That may seem like a backwards way of doing things, but it might be a way to approach problems from a different angle. My guess is (having not read much scientific biography it's hard to say) there were probably some scientists who developed the key ideas of their breakthroughs prior to completing formal training in their field. Besides, it's a lot more effort for me to learn all this stuff then to just ask the question on on Internet forum!
I'm also not worried about becoming that Mensan. That dude put too much emotional stakes into being right about that. He is completely emotionally invested in the correctness of his idea and his own brilliance over Einstein. I'm keenly aware of the fact that I'm just some dude throwing some half-baked idea onto an Internet forum. I'm not at all worried if people think it's crazy or wrong. And I'm not worried if it is wrong! What worries me more is if people don't think it's worth the time of day or is completely uninteresting. That would make me sad but not hugely sad, just kinda sorta sad. My contention is merely the idea is interesting enough to take somewhat seriously.
comment by MrMind · 2015-08-18T08:35:45.143Z · LW(p) · GW(p)
There is a fundamental flaw in this reasoning, as I see it. Even quantum mechanics puts a limit to the speed of every physical interactions. This means that whatever universe destroying event is happening, it is still constrained to travel at the speed of light. But the universe is very big, and even if the event happens inside our cosmological horizon, it would still takes billion of years to destroy it all.
This violates Tegmark's point n° 2: if the coin flip happens in a region outside the moon orbit, we would have plenty of time to observe it. But since we do not observe them at all, this means either of two things:
1) we are in a very atypical universe;
2) universe destroying events do not happen;
thus undermining the Fragile Universe Hypothesis. To be specific, it's your point n° 2 that doesn't follow through.
But are we in an extremely atypical universe? This is a classical problem with MWI, of which quantum suicide is just a tiny subset: since there's no way to assign a probability to different branches, there's a fortiori no way to assign a probability to those branches that witness extreme violations of classical mechanics (which we do not observe).
Replies from: Lumifer↑ comment by Lumifer · 2015-08-18T14:34:30.770Z · LW(p) · GW(p)
coin flip happens in a region outside the moon orbit, we would have plenty of time to observe it.
Information travels at the speed of light as well. If death flies towards you at the speed of light, you have zero time to observe it.
Replies from: MrMindcomment by gilch · 2016-01-06T20:52:29.955Z · LW(p) · GW(p)
Has this ever been seriously considered? (I’ve done some homework but undoubtedly not enough).
This idea is hardly new here. See Simulation, Consciousness, Existence by Hans Moravec, Permutation City by Greg Egan, and the Quantum Physics Sequence by our own Yudkowsky (especially the Many Worlds parts with the Ebborians, starting with Where Physics Meets Experience) and Robin Hanson's mangled worlds, which might help to explain some of the odd probabilities we find in quantum mechanics.
Replies from: PeterCoin↑ comment by PeterCoin · 2016-05-29T07:16:48.034Z · LW(p) · GW(p)
These are some very good links. I'm still digesting them. Thank you!
I've at least gave them all a once over (with the exception of Permutation City which awesome as it looks suffers from my general failure to incorporate fiction into my life) but definitely need to dig deeper. There's so much cool stuff out there that I'm still scratching the surface on.
Hans Moravec's Mind Children, I think comes closest to my argument. but stops short of stating that quantum suicide type scenarios might skew our understanding of physical law.
Anyways I'm just curious as to what else you've seen in a similar vein.
comment by Squark · 2015-08-23T18:28:20.435Z · LW(p) · GW(p)
Hi Peter! I suggest you read up on UDT (updateless decision theory). Unfortunately, there is no good comprehensive exposition but see the links in the wiki and IAFF. UDT reasoning leads to discarding "fragile" hypotheses, for the following reason.
According to UDT, if you have two hypotheses H1, H2 consistent with your observations you should reason as if there are two universes Y1 and Y2 s.t. Hi is true in Yi and the decisions you make control the copies of you in both universes. Your goal is to maximize the a priori expectation value of your utility function U where the prior includes the entire level IV multiverse weighted according to complexity (Solomonoff prior). Fragile universes will be strongly discounted in the expected utility because of the amount of coincidences required to create them. Therefore if H1 is "fragile" and H2 isn't, H2 is by far the more important hypothesis unless the complexity difference between them is astronomic.
Replies from: PeterCoin↑ comment by PeterCoin · 2015-08-26T00:06:56.940Z · LW(p) · GW(p)
I'm digging into this a little bit, but I'm not following your reasoning. UDT from what I see doesn't mandate the procedure you outline. (perhaps you can show an article where it does) I also don't see how which decision theory is best should play a strong role here.
But anyways I think the heart of your objection seems to be "Fragile universes will be strongly discounted in the expected utility because of the amount of coincidences required to create them". So I'll free admit to not understanding how this discounting process works, but I will note that current theoretical structures (standard model inflation cosmology/string theory) have a large amount of constants that are considered coincidences and also produce a large amount of universes like ours in terms of physical law but different in terms of outcome. I would also note that fragile universe "coincidences" don't seem to me to be more coincidental in character than the fact we happen to live on a planet suitable for life.
Lastly I would also note that at this point we don't have a good H1 or H2.
Replies from: Squark↑ comment by Squark · 2015-08-29T19:13:02.243Z · LW(p) · GW(p)
I'm digging into this a little bit, but I'm not following your reasoning. UDT from what I see doesn't mandate the procedure you outline. (perhaps you can show an article where it does) I also don't see how which decision theory is best should play a strong role here.
Unfortunately a lot of the knowledge on UDT is scattered in discussions and it's difficult to locate good references. The UDT point of view is that subjective probabilities are meaningless (the third horn of the anthropic trilemma) thus the only questions it make sense to ask are decision-theoretic questions. Therefore decision theory does play a strong role in any question involving anthropics. See also this.
But anyways I think the heart of your objection seems to be "Fragile universes will be strongly discounted in the expected utility because of the amount of coincidences required to create them". So I'll free admit to not understanding how this discounting process works...
The weight of a hypothesis in the Solomonoff prior equals N 2^{-(K + C)} where K is its Kolomogorov complexity, C is the number of coin flips needed to produce the given observation and N is the number of different coin flip outcomes compatible with the given observation. Your fragile universes have high C and low N.
...but I will note that current theoretical structures (standard model inflation cosmology/string theory) have a large amount of constants that are considered coincidences and also produce a large amount of universes like ours in terms of physical law but different in terms of outcome.
Right. But these are weak points of the theory, not strong points. That is, if we find an equally simple theory which doesn't require these coincidences it will receive substantially higher weight. Anyway your fragile universes have a lot more coincidences than any conventional physical theory.
I would also note that fragile universe "coincidences" don't seem to me to be more coincidental in character than the fact we happen to live on a planet suitable for life.
In principle hypotheses with more planets suitable for life also get higher weight, but the effect levels off when reaching O(1) civilizations per current cosmological horizon because it is offset by the high utility of having the entire future light cone to yourself. This is essentially the anthropic argument for a late filter in the Fermi paradox, and the reason this argument doesn't work in UDT.
Lastly I would also note that at this point we don't have a good H1 or H2.
All of the physical theories we have so far are not fragile, therefore they are vastly superior to any fragile physics you might invent.
Replies from: PeterCoin↑ comment by PeterCoin · 2015-08-30T19:49:20.491Z · LW(p) · GW(p)
I'll dig a little deeper but let me first ask these questions:
What do you define as a coincidence?
Where can I find an explanation of the N 2^{-(K + C)} weighting?
Replies from: Squark↑ comment by Squark · 2015-09-03T18:24:16.378Z · LW(p) · GW(p)
A "coincidence" is an a priori improbable event in your model that has to happen in order to create a situation containing a "copy" of the observer (which roughly means any agent with a similar utility function and similar decision algorithm).
Imagine two universe clusters in the multiverse: one cluster consists of universe running on fragile physics, another cluster consists of universes running on normal physics. The fragile cluster will contain much less agent-copies than the normal cluster (weighted by probability). Imagine you have to make a decision which produces different utilities depending on whether you are in the fragile cluster or the normal cluster. According to UDT, you have to think as even you are deciding for all copies. In other words, if you make decisions under the assumption you are in the fragile cluster, all copies make decisions under this assumption, if you make decisions under the assumption you are in the normal cluster, all copies make decisions under this assumption. Since the normal cluster is much more "copy-dense", it pays off much more to make decisions as if you are in the normal cluster (since utility is aggregated over the entire multiverse).
The weighting comes from the Solomonoff prior. For example, see the paper by Legg.
comment by HungryHobo · 2015-08-20T13:13:42.941Z · LW(p) · GW(p)
I'm not following your objection to quantum immortality, I will note that it also almost guarantees a version of yourself living forever but developing and maintaining a strong belief in "The Dark Lord Santa". There is little difference between annihilation and any other state, the idea that there is a universe where x did or did not happen.
If you're resting your argument on that then you can't draw a line around one state and claim it's special.
Replies from: PeterCoin↑ comment by PeterCoin · 2015-08-22T05:49:44.663Z · LW(p) · GW(p)
My objection is to the subjective experience of immortality. The multiple worlds gives rise to the illusion of probability. where it seems to us that quantum outputs are chosen randomly (because the vast majority of us experience arbitrary sequences when performing a series of quantum measurements). It is proposed that we should expect ourselves to find ourselves eventually living far beyond our natural years because of this observer selection effect. I would counter that that expectation comes from a naive view of selfhood that treats it like an all-or-nothing thing rather than something far slipperier.
I don't deny that some timelines have versions of me that may "live forever".
Replies from: HungryHobo↑ comment by HungryHobo · 2015-08-24T09:23:42.633Z · LW(p) · GW(p)
My objection is that it's irrelevant: It doesn't provide any useful information or anything that should guide your behavior because if every possible scenario is played out there's little difference between choosing to go for chemo and jumping off a bridge.
We're stuck with 1 subjective timeline. The other trousers of time aren't really relevant to us.
Replies from: PeterCoin↑ comment by PeterCoin · 2015-08-25T05:38:06.388Z · LW(p) · GW(p)
I'm not quite grasping what you're trying to get it here. Please do elaborate and clarify!
When you say "It's irrelevant" and "it doesn't provide any useful information or anything that should guide your behavior" what are you referring to?
Choosing to go for chemo and jumping off a bridge should have different results, The difference between the two results would be the basis for the decision. I don't see how fragile universe hypothesis or MWI should undermine that.
As for the relevance of other timelines, I have four answers:
MWI allows for quantum interactions with other timelines which means they're directly relevant
MWI provides for multiple future timelines for me, despite the fact these future mes will not have a "me-ness" relationship with each other. All future versions of me are relevant to current me.
Exploring this concept may result in theoretical predictions that are testable and eventually provide pragmatic benefits
I would like to understand what exists and why. I would like the Truth regardless of pragmatic benefits associated with it,
↑ comment by HungryHobo · 2015-08-25T10:02:51.574Z · LW(p) · GW(p)
irrelevant to decision-making. The idea that out of the [finite number so large that it's probably hard to express even with Knuth's up-arrow notation] possible future me's there's likely some which live an insanely long time or [reach any other state] isn't useful.
MWI may be useful to physicists and mathematicians but it's not the kind of relevant that means anything to normal decision making. Unless your job is programming a quantum computer it's totally irrelevant to your life.
You do not get to good results by saying "well one of the future me's will do fine in the MW's"
It implies that there is a future you for whom by random chance all genetic degradation will fail to happen and that random motion of molecules will replenish all his Telomeres at once halting aging while around him by pure chance gasses happen to separate into lower entropy states etc.
Though lets not forget the future you who's cell walls all suddenly burst by chance at the same time.
But that's not useful to you. Banking on one or the other or using it as a reason to not worrying about something doesn't help you.
comment by Jan_Rzymkowski · 2015-08-18T20:11:02.628Z · LW(p) · GW(p)
- It must kill you (at least make you unconscious) on a timescale shorter than that on which you can become aware of the outcome of the quantum coin-toss
- It must be virtually certain to really kill you, not just injure you.
Both seem to be at odds with Many World Interpretation. In infinite number of those it will just injure you and/or you will become aware before, due to same malfuntion.
Replies from: PeterCoin↑ comment by PeterCoin · 2015-08-19T14:14:42.557Z · LW(p) · GW(p)
I'm not sure what you're trying to draw from here, but I don't think MWI requires an infinite number of possibilities.
What matters is in my interpretation of Tegmark's view is that there are many many more cases (by infinite or finite measure) where it works properly than cases where it doesn't.
Example: 499,999,999,999,000 cases cause death without observer experience 500,000,000,000,000 cases do nothing 1000 cases represent equipment failures
We should expect that the subject can predict for himself the do nothing case will occur with extremely high probability.
comment by pragmatist · 2015-08-18T03:11:41.945Z · LW(p) · GW(p)
How is this:
What we may think are fundamental laws of our universe, are merely descriptions of the nature of possible futures consistent with our continued existence.
compatible with this:
Everett Many Worlds is either correct or at least on the right track
Is quantum mechanics an exception to the claim that our conception of the fundamental laws is based on an observation selection effect? Why would it be one?
Replies from: PeterCoin↑ comment by PeterCoin · 2015-08-18T05:48:57.530Z · LW(p) · GW(p)
Quantum mechanics is definitely not immune, that's where we should see the manifestation of the bias I'm proposing. When I refer to Everett many words I'm referring specifically to the property of it where an observer "branches" into multiple successor observers (which I extend to include branches where there are no successor observers).
But which laws would be affected and which would not, I'm not at all certain. It could be some, or all (or, of course, none, if I'm wrong). My proposal is to use this sort of reasoning to develop "deeper" fundamental laws.