Parapsychology: the control group for science

Parapsychologists are constantly protesting that they are playing by all the standard scientific rules, and yet their results are being ignored - that they are unfairly being held to higher standards than everyone else. I'm willing to believe that. It just means that the standard statistical methods of science are so weak and flawed as to permit a field of study to sustain itself in the complete absence of any subject matter.

— Eliezer Yudkowsky, Frequentist Statistics are Frequently Subjective

Imagine if, way back at the start of the scientific enterprise, someone had said, "What we really need is a control group for science - people who will behave exactly like scientists, doing experiments, publishing journals, and so on, but whose field of study is completely empty: one in which the null hypothesis is always true.

"That way, we'll be able to gauge the effect of publication bias, experimental error, misuse of statistics, data fraud, and so on, which will help us understand how serious such problems are in the real scientific literature."

Isn't that a great idea?

By an accident of historical chance, we actually have exactly such a control group, namely parapsychologists: people who study extra-sensory perception, telepathy, precognition, and so on.

There's no particular reason to think parapsychologists are doing anything other than what scientists would do; their experiments are similar to those of scientists, they use statistics in similar ways, and there's no reason to think they falsify data any more than any other group. Yet despite the fact that their null hypotheses are always true, parapsychologists get positive results.

This is disturbing, and must lead us to wonder how many positive results in real science are actually wrong.

The point of all this is not to mock parapsychology for the sake of it, but rather to emphasise that parapsychology is useful as a control group for science. Scientists should aim to improve their procedures to the point where, if the control group used these same procedures, they would get an acceptably low level of positive results. That this is not yet the case indicates the need for more stringent scientific procedures.

Acknowledgements

The idea for this mini-essay and many of its actual points were suggested by (or stolen from) Eliezer Yudkowsky's Frequentist Statistics are Frequently Subjective, though the idea might have originated with Michael Vassar.

This was originally published at a different location on the web, but was moved here for bandwidth reasons at Eliezer's suggestion.

Comments / criticisms

A discussion on Hacker News contained one very astute criticism: that some things which may once have been considered part of parapsychology actually turned out to be real, though with perfectly sensible, physical causes. Still, I think this is unlikely for the more exotic subjects like telepathy, precognition, et cetera.

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In no way do I think that the parapsychologists have good hypotheses or reasonable claims. I also am a firm adherent to the ethos: Extraordinary claims must have extraordinary proofs. However to state the following:

one in which the null hypothesis is always true.

is making a bold statement about your level of knowledge. You are going so far as to say that there is no possible way that there are hypotheses which have yet to be described which could be understood through the methodology of this particular subgroup. This exercise seems to me to be rejecting these studies intuitively,(without study) just from the ad hominem approach to rejection - well they are parapsychologists therefore they are wrong. If they are wrong, then proper analysis would indicate that, would it not?

I have never seen a parapsychology study, so I will go look for one. However does every single study have massive flaws in it?

I have never seen a parapsychology study, so I will go look for one. However does every single study have massive flaws in it?

Damien Broderick's Outside the Gates of Science summarizes a number of parapsychology studies, noting that several of the studies do indeed seem quite solid. It doesn't come to any definite conclusion over whether psi phenomena are actually real or if there's just something wrong with our statistical techniques, but it does seem like there might be enough to warrant more detailed study. See also e.g. Ben Goertzel's review of the book.

You are going so far as to say that there is no possible way that there are hypotheses which have yet to be described which could be understood through the methodology of this particular subgroup. This exercise seems to me to be rejecting these studies intuitively,(without study) just from the ad hominem approach to rejection - well they are parapsychologists therefore they are wrong. If they are wrong, then proper analysis would indicate that, would it not?

This is exactly the point. Parapsychology is one of the very few things we can reject intuitively, because we understand the world well enough to know that psychic powers just can't exist. We can reject them even when proper analysis doesn't indicate that they're wrong, which tells us something about the limitations of analysis.

ETA: Essentially, if the scientific method can't reject parapsychology, that means the scientific method isn't strong enough, not that parapsychology might be legitimate.

There are many other things that people have claimed can be rejected intuitively without study through the years.

In the 18th century, everyone knew that real scientific physics only permitted a body to act upon another body through direct contact. When Newton proposed his theory of gravity, many people rejected it as pseudoscientific or magical because it claimed the stars and planets could exert action at a distance, without saying how they did it.

In the 19th century, everyone knew that life was on a different order than mere matter, because obviously you couldn't produce the self-moving and self-regenerating qualities of life with just stuff like you get in rocks and sand.

In the 20th century, everyone knew that the mind was more than just the brain, since simple introspection could determine the existence of a consciousness inexplicable in simple material terms.

The absurdity heuristic is an okay heuristic, but I'd be really really careful before saying something is so absurd we can throw away any contradictory experimental evidence without a glance.

The possibility I give to some sort of psi effect existing (in a nice, scientific way that we can study once we figure out what form of matter/energy forms its substrate) is pretty low, but not zero. I'm not even willing to give it a tiny one in a bajillion probability - remember that people who say they're 99% sure of something are wrong 20% of the time, and that since this issue is "politically" charged, vaguely defined, and possibly affected by knowledge we don't have, this is exactly the sort of thing we'd be likely to be overconfident on. If this was some calibration test, I wouldn't feel too good about placing more than 95% or so on the nonexistence of psi.

And if you're a Bayesian, a couple of good studies should be able to start manipulating that 5% number upwards

I used to think that way before I knew about Bayesianism. Once I learned about it I realized that the prior probability for psi was very VERY low, e.g. its complex and there's no reason to expect it so one in a bajillion, while the probability for the observed evidence for psi, given what we know about psychology, was well in excess of 50% in the absence of psi, so the update couldn't justify odds greater than two in a bajillion.

One in a bajilion? Guys, the numbers matter. 10^-9 is very different from 10^-12, which is very different from 10^-15. If we start talking about some arbitrarily low number like "one-in-a-bajillion" against which no amount of evidence could change our mind, then we're really just saying "zero" but not admitting to ourselves that we're doing so.

Other than that, I agree with Yvain and have found this to be perhaps the most belief-changing so far on LW!

It takes only 332 pieces of evidence with likelihood ratios of 2:1 to promote to 1:1 odds a hypothesis with prior odds of 1:googol, that is 10^-100, which would be the appropriate prior odds of something you could describe with around 70 symbols from a 26-letter equiprobable alphabet.

"A bajillion to one" are odds that Bayesian updating can overcome surprisingly quickly - it isn't anything remotely like "no amount of evidence can change my mind". Now odds of one to a googolplex - that might as well be zero, relative to the amount of evidence you could acquire over a human lifetime. But the prior probability of any possibility you can describe over a human lifetime should be much higher than that.

A nitpick: it takes 332 pieces of all mutually independent evidence to perform that level of update.

More confusing, for these purposes the independence level of the evidence depends on what hypotheses you're trying to distinguish with it. E.g. if you're trying to distinguish between "that subject has ESP powers" and "that experiment was random luck" then 332 repetitions of the same experiment will do. If you're trying to distinguish between "that subject has ESP powers" and "that experimenter's facial expressions differ based on what cards he was looking at", then you can't just repeat it; you've got to devise new and different experiments.

You're right that I completely missed the Bayesian boat, and I'm going to have to start thinking more before I speak and revise my estimates down to <1%.

But I'm still reluctant to put them as low as you seem to. The anthropic principle combined with large universe says that whatever complexity is necessary for the existence of conscious observers, we can expect to find at least that level of complexity. Questions like consciousness, qualia, and personal identity still haven't been resolved, and although past experience suggests there is probably a rational explanation to this question, it isn't nearly dissolved yet. If consciousness really is impossible without some exotic consciousness-related physics (Penrosean or otherwise), then our universe will have exotic consciousness-related physics no matter how complex they need to be. And since evolved beings have been so proficient at making use of normal physics to gain sensory information, it's a good bet they'd do the same with exotic consciousness-related physics too if they had them...

...is a somewhat hokey argument I just invented on the spot, and I'm sorry for it. But the ease with which I can put something like that together is itself evidence that there are enough possible sides of the issue that hadn't been considered (at least I hadn't considered that one; maybe you've been thinking about it for years) that it needs at least a little more room for error than two in a bajillion (sorry, Alex).

I also disagree with your assessment of the amount of evidence. Have you ever read any good books by intelligent believers in the subject? It's not all John Edwards psychic chat shows. I also think you might be double-counting evidence against psi here - psi doesn't exist so we know any apparent evidence must come from human psychology, therefore there never was any apparent evidence in the first place. Or have you read the studies and developed separate explanations for each positive result?

Anyway, let's settle this the LW way. Give me your odds that psi exists, and we can make a bet at them. If it's one in a million, then I'll give a cent to your favorite charity on the condition that you give $10,000 to my favorite charity if psi's shown to exist within our lifetimes (defined however you want; possibly as evidence sufficient to convince any two among Randi, Dawkins, and Eliezer that psi is >50% likely).

One problem with this argument is that if psi exists, we are very bad at using it, and we don't see other organisms using it well either. The world we see appears to be almost completely described by normal physics at worst.

I don't think that I'm double-counting evidence. I certainly know that there can be intelligent believers, after all, MANY intelligent people believe that one is compelled to accept the conclusions of the scientific method over those of the scientific community. Also, beliefs can be compelling for any variety of irrational reasons. The evidence I have seen though looks to me like exactly the evidence you would expect given known psychology and no psi. We can surely agree that there is a LOT of evidence that hyman psychology would create belief in psi in the absence of psi, can't we.

I would set my odds at "top twenty most astoundingly surprising things ever discovered but maybe not top ten". That seems to me like odds of many billions to one against, but not trillions. Unfortunately, the odds for almost any plausible winning conditions occurring without psi being real are much higher, making the bet difficult to judge. I have a standing 10,000 to one bet against Blacklight Power's "Hydrino Theory" with Brian Wang based on a personal estimate of odds MUCH less than 1-in-10K for "Hydrino Theory" and I'm happy to extend those odds when the odds are still more favorable, but psychotic breaks by two people in a group of three? If the odds per person are 1%, that gives odds of about 1:3300. I'm happy to give those odds on the Dawkins, Randi Yudkowsky bet and count "psi is actually real" as a rounding error.

Have donated $10 to SIAI (seemed less likely to lose you guys money in transaction fees than $1) with public comment about the bet . Will decide where you can donate your $33000 in the unlikely event it proves necessary.

I'd feel ridiculously overconfident stating a probability of less that 1e-6, yet I don't have the slightest hesitation to take that bet. (Brain sucks at small probabilities.) Condition is any two among {Randi, Dawkins, Eliezer, Vassar, me}, but if one is reported to have developed a new mental illness at least two months before they say psi is real, they don't count.

Also, let's make it purchasing power as of 2011, not dollar amount. Assuming scarcity lasts long enough.

Well, then I lose the bet...unless someone contacts their ghosts...in which case I win the bet!

Psi doesn't even explain consciousness or qualia.

[edit] Oops, necro. Disregard me.

[edit edit] okay! nevermind that then :D

I don't think there's a prejudice against replying to old posts around here...

One in a bajillion? You are saying you actually know how complex psi is without even saying what aspect of psi you are talking about.

We know biology is very complex. So when testing a supplement like creatine, the pseudoskeptic could say "biology is extremely complex. We do not know the mechanism that makes creatine work so I assign a very low bayesian probability. Today I feel like a hundred trillion to one".

Keep in mind this is after several studies have shown an effect in the predicted direction whose odds are not easily explained by chance. Indeed, there is nothing wrong with you assertion about complexity just the subjective part where you assign a number to a phenomena you are not very familiar with.

One in a bajillion? You are saying you actually know how complex psi is without even saying what aspect of psi you are talking about.

Bajillion isn't exactly a precise measure. In this context it means 'lots'. That isn't hard to assign to the all aspects of psi.

In the 20th century, everyone knew that the mind was more than just the brain, since simple introspection could determine the existence of a consciousness inexplicable in simple material terms.

No, they didn't. Superficial research indicates that serious materialism goes back to at least the Enlightenment in the 18th century. And the 20th century? That's not even plausible.

Good point, with the qualifier that many people (including professional philosophers) presently find themselves unable to wrap their heads around the idea that they have no non-material consciousness. The "argument from absurdity" against materialism is alive and kicking.

Parapsychology is one of the very few things we can reject intuitively, because we understand the world well enough to know that psychic powers just can't exist.

Do you think it is possible that we are "living in the Matrix"? If so, then you should consider something functionally indistinguishable from psychic powers to be possible.

If we are, in fact, living in the Matrix, then science has already characterized the rules of the simulation rather well. Barring further interference by the sysadmin/God/whatever, it should continue to operate by mechanistic, semipredictable rules. Science has little to say about one-time interventions from outside observable reality, whether you call them "Matrix hacks", "miracles", or what you will. Regarding such matters, the null hypothesis has yet to be convincingly falsified, but absence of proof is not proof of absence.

It's a fairly common thing, in videogame design, to include "cheat codes:" obscure, highly specific, and seemingly useless in-game behaviors which produce otherwise impossible results.

The hypothesis that we are living in the Matrix is best understood as a metaphysical hypothesis. The various claims made by parapsychologists, however, are not metaphysical claims about the nature of reality, but "scientific" claims about what goes on in reality. It is therefore unclear why such claims would be more probable on the assumption that the Matrix hypothesis is true.

I am not surprised when a video game character consistently summons balls of fire out of nothingness. I would be absolutely astounded to see an actual person do this. This is because the system of rules governing a video game and the system governing a deterministic universe appear to be very, very different.

If we were living in the matrix, this would not be the case. It would not mean that we are necessarily in the kind of video game where there are psychic powers, but it would provide a very clear mechanism through which psychic powers could act. Such a mechanism does not appear possible in a deterministic universe, or at least in the one we seem to occupy.

Real world is uncaring, unsupervised. Magic is not just about the world being "complex", it's about the world containing mechanisms targeting specifically humans, and understanding the situation much like a human would. Being "deterministic" doesn't preclude anything, it's more of a way of seeing things than the way things are.

This is because the system of rules governing a video game and the system governing a deterministic universe appear to be very, very different.

An artificial dichotomy.

I don't think so. Video games are specifically programmed to create a particular experience for the user. If something goes over the horizon and won't be needed again, it just doesn't get computed. Whereas the real universe seems to be---just the same physics. Everywhere. No complicated ad hoc programming describing levels or characters or points, or translating keypresses into useful actions---no user input at all, come to think of it.

If something goes over the horizon and won't be needed again, it just doesn't get computed. Whereas the real universe seems to be---just the same physics. Everywhere.

Not quite. That's what we assume happens -- justifiably! -- because it would be a far more complicated hypothesis to disbelieve in the implied invisible.

However, failing to see these implied invisibles is not itself independent evidence of universal law, just an inference from an Occamian prior. You would fail to see implied invisibles with equal probability whether or not the laws were fully universal.

Interestingly, I explored the question of whether it's possible, if the universe is a simulation, to shut it down by forcing it to do more and more computational work in order to keep fooling us. But, I argue, it turns out that the 2nd law of thermodynamics implies that no matter what observations observers choose to make, it requires no more storage capacity to continue fooling them.

But, I argue, it turns out that the 2nd law of thermodynamics implies that no matter what observations observers choose to make, it requires no more storage capacity to continue fooling them.

I read this, but I'm a little confused. Conceptually, as a closed system, the demand of universe is constant, sure, when I imagine it as something like the game of Life. Are you assuming that any simulator will be a full and perfect emulator, with no optimizations like caches?

Because if optimizations are applied, then it seems you can expand the necessary power by doing things that defeat the optimizations. Caches are ineffective if you keep generating intricately linked cryptographic junk, etc. One might think that no simulating agent would run a simulator whose worst-case requirements are beyond its abilities; but then, we humans routinely use QuickSort and don't mind our kernels over-committing memory...

(Incidentally, I made an estimation of my own for how small our substrate could be: http://www.gwern.net/Simulation%20inferences.html . I concluded that the simulating computer could be as small as a Planck cube.)

Are you assuming that any simulator will be a full and perfect emulator, with no optimizations like caches?

It doesn't rely on that assumption. It's just based on the fact that any time you destroy entropy by forcing some system, from your perspective, to be in fewer possible states, you also allow another system, from your perspective, to be in proportionally more possible states.

The more states something could be in, from your perspective, the less information the simulator has to store to consistently represent it for you.

You make an interesting observation. I'm still trying to think it through, so I might not yet be making sense. But, right now, I have the following difficulty with accepting your argument.

Any simulation has "true" physical laws. These are just the rules that govern how in fact the simulation's algorithm unfolds, including all optimizations, etc.

However, we expect, a priori, the ultimate laws of reality to satisfy certain invariances. For example, perhaps we expect the ultimate laws to work identically at different points in real physical space. The true laws of the simulation might not satisfy such invariances with respect to the simulation. For example, the simulation's laws might not work identically at different points in the simulated physical space. [ETA: Optimization makes this likely. The simulation could evolve in a "chunkier" way far from us than it does close to us.]

So maybe this is how we can define what it means to hide the simulated nature of our universe from us: "Hiding the simulation" means "making our universe appear to us as though its laws satisfy all the expected invariances, even though they don't".

Here's the issue that I hope you address:

I'm convinced by your argument that "any time you destroy entropy by forcing some system, from your perspective, to be in fewer possible states, you also allow another system, from your perspective, to be in proportionally more possible states."

Say that, when I start out, system A could be in any one of the states in some state-set X. Then I learn about system B, and so, as you point out, system A could now be in any one of the states in some larger state-set Y, as far as I know.

But what if the larger state-set Y includes states that do not obey the expected invariances? And what if, as I learn more about the universe, the state-set that A's state must be in grows, all right, but eventually consists almost entirely of states that violate our expected invariances?

Wouldn't that amount to discovering the simulated nature of our universe? To avoid this discovery, wouldn't the simulators have to put more resources into making sure that A's set of possible states includes enough states that obey the expected invariances?

Good point -- I've struggled with the same problem, in different terms. Let me know if my statement of the problem matches the point you're making here:

"It's possible to discover, not just particulars about individual systems, but universal laws. These universal laws put a constraint on all future observations, thus reducing the subjective entropy of the universe, without (apparently) needing any corresponding gain of entropy."

It's something I was wondering about when going over the E. T. Jaynes papers and Yudkowsky's Engines of Cognition.

I haven't gotten it resolved in terms of 2nd law and the "subjective entropy" idea, but I think I know how to resolve it in the context of the simulated universe question: basically, if the simulation starts out adhering to the invariances that have to be obeyed (even though they might be more than necessary to fool observers), then it is no additional burden for the observers to notice these invariances.

Though the observers have (apparently) violated the 2nd law -- and this is an area for further research -- the simulator was already expending the computational resources necessary to make the invariances hold. It is an exception to the general principle I derived, in that it's a case where net destruction of entropy requires no additional RAM.

I'm still working on how to resolve the remaining problems, but it shows how discovery of universal physical laws needn't be a problem for the simulator.

I'll try to bring your solution back to thermodynamics terms:

The universe always has and always will obey certain invariances, and those are a redundancy in your observations, which (along with any other redundancy that could possibly be derived) is already taken into account when computing information-theoretic entropy. If you had plenty of data already to derive the invariance but just hadn't previously noticed it, that lack of logical omniscience is why the 2nd law is an inequality. Including the invariance into your future predictions isn't a net reduction in entropy. It just removes some of the slack between the exact phase-volume preserving transforms of physics and the upper bounds that a computationally bounded agent has to use.

Your restatement looks exactly right, and your solution would resolve the issue I raised.

One question is, how much optimization can the simulators do if the true laws are as invariant as they "ought to be"? For example, if the universe has to evolve according to the same rules everywhere, that would seem to keep it from evolving in a chunkier way far away from us, which closes off a potential way to save on computation.

The simulator can maintain conservation of e.g. mass, while not churning through the computations required for e.g. gravity until people see enough that they can check if gravity isn't holding.

This would save on having to do the gravity calculations. Then, when people, armed with their knowledge of gravity, start looking in more places, the universe must pick a configuration and stick with it -- but at that point, all of their observations have the original problem of freeing up memory somewhere else in the form of higher entropy.

On second thought, that doesn't work either, since discovery of gravitational laws will constrain their existing predictions of where the planets will be, and this destruction of entropy is unrelated to the entropy needed to create it, which was your objection to begin with.

My best guess at this point is that any resolution will ultimately hinge on a finer-grained information-theoretic analysis of the discovery of universal laws. That is, as you gain evidence pointing to the validity of laws you notice, you assign a high-but-not-unity probability to the laws continuing to hold. Each time your probability goes up, that corresponds to a particular reduction in the entropy of your probability distribution.

But, as they say, "to make inferences you have to make assumptions". There is some entropic cost to making the assumptions necessary for the model with invariants to work, and this must be properly accounted for. I'll continue to research this.

This would save on having to do the gravity calculations. Then, when people, armed with their knowledge of gravity, start looking in more places, the universe must pick a configuration and stick with it -- but at that point, all of their observations have the original problem of freeing up memory somewhere else in the form of higher entropy.

This is wrong (even assuming that previous coarse-grained observations don't matter). If you are changing the model by refining it, choosing one option of more detailed data arbitrarily, then this process on the world-model isn't reversible: you can't "un-choose" that arbitrary data and remain able to reconstruct it (unless the data is not arbitrary after all and only depends on the world model that is already there). As a result, no magical increase in entropy occurs, and no resources get saved: it's not an operation on the subsystems within the modeled world, it's an operation on the system of whole-world model within the world of modelers.

Also, consider the fact that ultimate laws can never be discovered, strictly speaking: there will always be uncertainty, and maybe there won't even be asymptotically certain candidates, only turtles always deeper and deeper.

I vaguely see what you're getting at - every observation or interaction forces the simulator to calculate what you see, but also allows it to cheat in other areas. But I'm not sure how exactly this would work on the level of bits and programs?

This is a very conceptually interesting question.

Bah! Implementation issue! :-P

At the level you're asking about (if I understand you correctly), the program can just reallocate the memory for whatever gained entropy, to whatever lost entropy.

Like in the comments section of my blog, if you learn the location of a ball, the program now has to store it as being in a definite location, but I also powered my brain to learn that, so the program doesn't have to be as precise in storing information about chemical bonds, which were moved to a higher entropy state.

Spoken like a true theoretician. But it's hard to see an implementation that is optimal in exploiting this memory bound.

I mean, imagine that we have a pocket universe where we can have many numbers (particles?) which all must add up to 1000, and we have your normal programming types like bit, byte/int, integer etc.

If we start out with 1 1000, and then the 'laws of physics' begins dividing it by 10, (giving us 10 100s), how is the simulator going to be smart enough to take its fixed section of RAM and rewrite the single large 1000 integer into 10 smaller ints, and so on down to 1000 1s which could be single bits?

Is there any representation of the universe's state which achieves these tricks automatically, or does the simulation really just have to include all sorts of conditionals like 'if (changed? x), then if x > 128, convert x Integer; x <= 128 && > 1, convert x int; else convert x bit' in order to preserve the constant-memory usage?

I don't think this hypothetical universe is comparable in the relevant ways: it must be capable of representing the concept of an observer, and what that observer knows (has mutual information with), and adhere to the 2nd law of thermodynamics. Which I don't think is the case here.

Wait, there has to be an observer? I thought you were really just talking about entangled wave-functions etc.

No, that's the point Jack brought up. I was only discussing the issues that arise in the hypothetical scenario in which the universe is simulated in an "overworld" and must successfully continue to fool us.

When I was first introduced to quantum mechanics my professor taught us the Copenhagen Interpretation. I was immediately reminded of occasional moments in video games where features of a room aren't run until the player gets to the room. It seemed to me that only collapsing the wave function when it interacted with a particular kind of physical system (or a conscious system!) would be a really good way to conserve computing power and that it seemed like the kind of hack programmers in an fully Newtonian universe might use to approximate their universe without having to calculate the trajectories of a googolplex (ed) subatomic particles.

Can anyone tell me if this actually would save computing power/memory?

googleplex = Google Inc's HQ

googolplex = 10^(10^100)

It's truly sad now how people are less familiar with the original spelling and meaning of a googol. Now the first thing we think of is the search engine, instead of 10^100.

Is that really so sad? googol was named in jest and I do not think I have ever seen it seriously needed for anything; Google on the other hand...

The answer basically comes down to the issue of saving on RAM vs. saving on ROM. (RAM = amount of memory need to implement the algorithm, ROM = amount of memory needed to describe the algorithm)

Video game programmers have to care about RAM, while the universe (in its capacity as a simulator) does not. That's why programmers generate only what they have to, while the universe can afford to just compute everything.

However, I asked the same question, which is what led to the blog post linked above, where I concluded that you wouldn't save memory by only doing the computations for things observers look at: first, because they check for consistency and come back to verify that the laws of physics still work, forcing you to generate the object twice.

But more importantly (as I mentioned) because the 2nd law of thermodynamics means that any time you gain information about something in the universe, you necessarily lose just as much in the process of making that observation (for a human, it takes the form of e.g. waste heat, higher-entropy decomposition of fuels). So by learning about the universe through observation, you simultaneously relieve it of having to store at least as much information (about e.g. subatomic particles).

(This argument has not been peer-reviewed, but was based on Yudkowsky's Engines of Cognition post.)

Assuming they don't make any approximations other than collapse, yes a classical computer simulating Copenhagen takes fewer arithmetic ops than simulating MWI. At least until someone in the simulation builds a sufficiently large coherent system (quantum computer), at which point the simulator has to choose between forbidding it (i.e. breaking the approximation guarantee) or spending exponentially many arithmetic ops.

Copenhagen (even in the absence of large coherent subsystems) does not take significantly less memory than MWI: both are in PSPACE.

Otoh, if the simulator is running on quantum-like physics too, then there's no asymptotic difference in arithmetic either. And if you're not going to assume that the simulator's physics is similar to ours, who says it's less rather than more computationally capable?

If you implemented the laws of physics on a computer, using lazy evaluation, then whatever is "over the horizon" from the observer process(es) would not be computed.

However, this would not in the least be observable from inside the system. If the observer moved to serve you, your past would be "retroactively" computed.

I'm not claiming this is very likely to be the case, since at the very least it requires an additional agent - the observer process - to cause anything to happen at all, but lazy evaluation isn't some weird ad-hoc concept; it's a basic concept in computer science that also happens to make programs shorter, a lot of the time.

Hopefully not sufficiently shorter that a universe using lazy evaluation with one random point in space somewhere as the observer is less complex than one using strict evaluation. That.. would be impossible for us to detect, of course, but I believe it'd still have consequences.

If the universe we're living in is a work of art or a game, it's made for minds with much greater processing power than we've got. It isn't obvious that they'd be satisfied with something as crude as a video game.

How about a video game where you attempt to control a pre-singularity global civilization by directly playing a few thousand randomly selected humans simultaneously, while not letting this fact be noticed by the NPCs?

It's interesting to wonder what sort of games post-humans might play, though I hope it won't be anything quite that ethically objectionable.

It's interesting to wonder what sort of games post-humans might play, though I hope it won't be anything quite that ethically objectionable.

Or, from the perspective of a pre-post-human, quite that dull. If I am going to play that kind of sim I'm going to pick the 'elves' faction.

Considering that there exist fork-lift simulation games, I hesitate to claim that anything is too dull to be made.

Considering that there exist fork-lift simulation games, I hesitate to claim that anything is too dull to be made.

You're serious? That scares me.

I think it was originally meant for training, but yes. People play it. As a game.

http://www.youtube.com/watch?v=HIVFjtZzDr8

It could be that it was the elves who picked the 'humans' faction.

If you can understand how the two are truly the same, you are far wiser than anyone I've ever met, and I would very much like to subscribe to your newsletter. I hope thefirst issue explains how this dichotomy is invalid.

A video game can be deterministic or not in the same way any other kind of universe can. "Video game" vs "deterministic" is just a silly comparison. I don't know what word to use in place of 'deterministic', I just don't think that one is the right one.

I'm thinking "algorithmic". That is, the universe, or a video game, follows a certain algorithm to determine what happens next, whether the algorithm is the laws of physics or a computer program. Algorithms aren't necessarily deterministic: we could have a step for "generate a truly random (quantum) number".

Huh? "Metaphysics" refers to an incredibly wide variety of claims. But I'd say that metaphysics tries to answer questions about reality that aren't the kind of questions that can be answered by experimental science. Since we lack a good method for answering these questions our confidence in metaphysical claims is usually substantially lower than it is for empirical claims. But why should we think all metaphysical questions are radically different from scientific questions such that the answer to one can't influence our estimations of the other? Of hand I can't think of a number of metaphysical hypotheses that have been greatly effected by scientific knowledge and vice versa-- materialism, substance dualism, determinism and indeterminism, free will, eternalism and philosophies of time etc.

In this case it seems rather obvious that if we are "living in the Matrix" the probability that the basic laws of physics are complicated rather than simple is dramatically higher.

I never denied that a our assessment of an empirical claim may be influenced by the metaphysical views we hold. I simply noted that, once the Matrix hypothesis is understood as a metaphysical hypothesis, it is unclear why believing that we live in the Matrix should increase our credence in the various claims of parapsychology.

I have no idea what your argument actually is. Why does it matter whether or not the Matrix hypothesis is a metaphysical hypothesis?

My original comment was a reply to Mitchell Porter, who suggested that parapsychology would somehow receive support from the Matrix hypothesis. I replied by saying that this would not be true, or at least not clearly, if that hypothesis is understood as a claim about the ultimate nature of reality.

To take another example, suppose someone argued Berkeleyan idealists should be more open to psychic phenomena, since we are all ideas in the mind of God. I would reply that this is not so, since the fact that the world is ultimately made of mind has in itself no implications about whether certain kinds of mental phenomena take place within that world.

The ability of certain collections of atoms to communicate large amounts of information to other collections of atoms over vast distances without there being any detectable emissions is an incredibly complex power. Complex entities are a priori improbable compared to simple entities. You need some kind of creation mechanism to make them probable... with biological systems we have evolution, with pocket watches and jet planes you have human inventors. If you accept a metaphysical hypothesis that involves an intelligence creating the universe-- programmers or God-- you have a mechanism for making complex entities probable. That is why the Matrix hypothesis makes psychic phenomena more likely

Complex entities are a priori improbable compared to simple entities.

This remains the case no matter what the universe is made of. All evidence suggests that psychic mechanisms are not available to us in our current mode of existence, whatever that may be. That evidence doesn't change until you get more.

At least, that seems to me to be the point ben is making.

Complex entities are a priori improbable compared to simple entities.

This remains the case no matter what the universe is made of.

Yes, but not no matter how the universe was created. The Matrix hypothesis includes a claim that the universe was created by some intelligence and that makes psychic phenomena substantially more plausible.

That doesn't mean all religious people have to believe in psychic phenomena or even that they should. If there is no evidence for psychic phenomena then there is not evidence for psychic phenomena. But if you think the universe was created claims of psychic phenomena should be less absurd on their face.

Yes, but not no matter how the universe was created. The Matrix hypothesis includes a claim that the universe was created by some intelligence and that makes psychic phenomena substantially more plausible.

Another position that could be taken is "the evidence suggests that if we are living in a matrix scenario then it is probably one of the ones without matrix psychic powers". That is, assuming rational reasoning without granting a counter-factual premise. The evidence can then be considered to have a fixed effect on the probability of psychic powers. Whether it causes you to also lower your probability for a Matrix or to alter your description of probable Matrix type would be considered immaterial.

Again, this is just what my impression of Ben's position. He'll correct me if I'm wrong. For my part I don't care about Matrixes (especially No. 2. I walked out of that one in disgust! Actually, I do care about the 'dodge this!' line. It's infuriating.)

This all started when Michell Porter responded to Blueberry's claim that we know, intuitively, that psychic phenomena are just not possible. I'm not quite sure I know just what Blueberry was talking about. But his estimate of the existence of psychic phenomena was zero and not just because of parapsychology's failure to provide convincing evidence but because of our understanding of the world. Mitchell provides Blueberry with a hypothesis that is consistent with what we know about the world but under which the existence of psychic phenomena is not prohibitively improbable.

None of this changes the fact that finding evidence of psychic phenomenon should cause us to revise our probabilities of its existence up and that non finding evidence should cause us to revise our probabilities down. But if your probability is zero, and especially if your probability is zero for reasons other than the failure of parapsychology, a hypothesis with P>0 where P(psi) is >0 looks like information you needs to update on.

Ben says it isn't clear why this is so. Well creation makes complex, unselected entities more probable. But maybe I should wait to have this argument with him.

As far as the movie goes, it is all downhill right after Neo wakes up gooey pink tub and sees all the other people hooked into the Matrix. The whole movie should have taken place in the Matrix and kept us in the dark about what it really was until the very end. Would have been way cooler that way.

But if your probability is zero, and especially if your probability is zero for reasons other than the failure of parapsychology, a hypothesis with P>0 where P(psi) is >0 looks like information you needs to update on.

Once your probability is zero is it even possible to update away? That'd more be 'completely discarding your entire understanding of the universe for reasons that cannot be modelled within that understanding'. If something is impossible then something else, no matter how unlikely, must be the truth. This includes the hypothesis "every thought I have that suggests the p(0) hypothesis must be true is the product of cosmic rays messing with my brain."

Well, if you believe in Cartesian skepticism (that is, that we might be in the Matrix), then your probability for anything can't ever be zero. Say the probability that this world is an illusion within another world is epsilon: in that case anything could be true. So the lowest probability we can assign to anything is epsilon. EY has a post on how 1 and 0 aren't probabilities.

If you observed psychic powers with no possibility of cheating, you should probably conclude that something metaphysically weird is going on: you're in a dream, you're insane, or there's a hole in the Matrix.

Well, if you believe in Cartesian skepticism (that is, that we might be in the Matrix), then your probability for anything can't ever be zero. Say the probability that this world is an illusion within another world is epsilon: in that case anything could be true. So the lowest probability we can assign to anything is epsilon. EY has a post on how 1 and 0 aren't probabilities.

Find the probability p(A | B) where B = "nothing weird like what the Cartesian sceptics talk about is going on". That gets rid of the Matrix issue. Then it is just a matter of whether or not you want to let dart players divide by infinity all willy nilly.

I've always been really confused by this but it isn't clear that an event with P=0 is an impossible event unless we're talking about the probability of an event in a finite set of possible events. (Edit again: You can skip the rest of this paragraph and the next if you are smarter than me and already get continuous probability distributions. I'm obviously behind today.)This is how it was explained to me: Think of a dart board with a geometric line across it. That line represents probability space. An event with P=.5 is modeled by marking the middle of the line. If someone throws a dart at the line there is an equal chance that it lands at any point along the line. However, at any given point the probability that the dart lands there is zero.

I think the probability of any particular complex entity, event or law existing can be said to have a probability of zero absent a creator or natural selection or some other mechanism for enabling complexity. Of course this is really counterintuitive since our evolved understanding of probability deals with finite sets of possibilities. Also it means that 'impossible' can't be assigned a probability. (Edit: Also, the converse is true. The probability that the dart lands anywhere other than the spot you pick is 1 so certainty can't be mapped as 1 either.)

Also, imperfect Bayesians will sometimes assign less than ideal probabilities to things. A perfect Bayesian would presumably never wrongly declare something impossible because it could envision possible future evidence that would render the thing possible. But regular people are going to misinterpret evidence and fail to generate hypotheses so they might sometimes think something is impossible only to later have it's possibility thrown in their faces.

Interesting point. Since physics does appear on the surface to be continuous, I can't rule out continuous propositions. Perhaps the amended saying should read "0 and 1 are not probability masses, and 0 is not a probability density."

Oh. I was expecting your belief to be as with infinite-set atheism: that we never actually see an infinitely precise measurement.

We don't, but what if there are infinitely precise truths nonetheless? The math of Bayesianism would require assigning them probabilities.

I've always been really confused by this but it isn't clear that an event with P=0 is an impossible event unless we're talking about the probability of an event in a finite set of possible events. This is how it was explained to me: Think of a dart board with a geometric line across it. That line represents probability space. An event with P=.5 is modeled by marking the middle of the line. If someone throws a dart at the line there is an equal chance that it lands at any point along the line. However, at any given point the probability that the dart lands there is zero.

And, having assigned p(A) = 0 to such an event A I will not be able to rationally update away from zero without completely discarding my former model. There is no evidence that can cause me to rationally update p(A) = 0 to something else ever. Discard it and overwrite with something completely unrelated perhaps, but never update. p(A) is right there as the numerator!

(But yes, I take your point and tentatively withdraw the use of 'impossible' to refer to p=0.)

ETA: Well, maybe you're allowed to use some mathematical magic to cancel out the 0 if p(B) = 0 too. But then, the chance of that ever happening is, well, 0.

Er, my bad. I missed your point. I see it now, duh.

So my friend thinks something S has a probability of zero but I know otherwise and point out that it is possible give assumption which I know my friend believes has a .1 chance of being true. He says "Oh right. I guess S is possible after all." What has just happened? What do we say when we see the dart land at a specific point on the line?

What has just happened?

Your friend had incorrectly computed the implications of his prior to the problem in question. On your prompting he re-ran the computation, and got the right answer (or at least a different answer) this time.

Perfect Bayesians are normally assumed to be logically omniscient, so this just wouldn't happen to them in the first place.

What do we say when we see the dart land at a specific point on the line?

In order to specify a point on the line you need an infinite amount of evidence, which is sufficient to counteract the infinitesimal prior. (The dart won't hit a rational number or anything else that has a finite exact description.)

Or if you only have a finite precision observation, then you have only narrowed the dart's position to some finite interval, and each point in that interval still has probability 0.

So my friend thinks something S has a probability of zero but I know otherwise and point out that it is possible give assumption which I know my friend believes has a .1 chance of being true. He says "Oh right. I guess S is possible after all." What has just happened?

You wasted a great gambling opportunity.

Pengvado gives one good answer. I'll add that your friend saying something has a probability of zero most likely means a different thing than what a Bayesian agent means when it says the same thing. Often people give probability estimates that don't take their own fallibility into account without actually intending to imply that they do not need to. That is, if asked to actually bet on something they will essentially use a different probability figure that incorporates their confidence in their reasoning. In fact, I've engaged with philosophers who insist that you have to do it that way.

What do we say when we see the dart land at a specific point on the line?

"Did not! Look closer, you missed by 1/infinity miles!"

Do you think it is possible that we are "living in the Matrix"? If so, then you should consider something functionally indistinguishable from psychic powers to be possible.

Yes, but then we would have to give up on the scientific method anyway, because the laws of physics would be whatever the adminstrators of the Matrix felt like changing them to.

What Jack said -- you can still notice regularities in the Matrix even if it's sometimes capriciously tampered with. That is, these overlords do not automatically make our universe a high-entropy white noise bath.

I discussed some of the implications of a simulated universe and the implications of the 2nd law of thermodynamics on it here.

The universe being a simulation does not entail that the administrators of such a simulation are capricious. And that we have demonstrated the existence of a large number of natural regularities suggests they are not.

Exactly! I guess Allan needs to explain further why parapsychology is bunk. As an example, a person 'reading the mind' of another person a mile away without the emission of any kind of detectable electromagnetic wave or signal capable of traveling that far is in violation of the laws of physics as we know them (and if people did emit such signals, it would be intensively studied). For this to be true, physics itself would need to be complicated on a level that would specifically allow this phenomenon to occur, which seems very, very unlikely. To quote Michael Vassar, "Magic is the hypothesis that physics is complicated."

We should expect positive results from the field of parapsychology, since so many people (in total over the years) are trying to prove it exists, and there is an extreme positive results bias. Thus by chance positive results will be obtained and published, while negative results are largely ignored or not even submitted (I assume a 'scientist' trying to prove parapsychology wants to do so, and so may only bother submitting a paper on the topic if the results are positive).

...Charles Honorton and his colleagues drew together all the forced-choice experimental precognition experiments reported in English between 1935 and 1987, publishing their findings in the December 1989 Journal of Parapsychology. The combined results were impressive: 309 studies contributed to by 62 senior authors and their associates, nearly two million individual trials made by more than 30,000 subjects. (In a properly conservative culling, all the experimental work of both Rhine's chosen but subsequently disgraced successor, Walter J. Levy, and S.G. Soal, once a famous specialist in time-displacement psi tests, was excluded; both were known to have cheated in at least some experiments.) Overall, the cumulation is highly significant - 30 percent of studies provided by 40 investigators were independently significant at the 5 percent level. Yet this was not due to a suspicious handful of successful researchers: 23 of the 62 (37 percent) found overall significant scoring.

By the same token, admittedly, this means 63 percent failed to show significant psi. But [...] [i]f one hundred studies are done, averaging as many as thirty-eight correct calls instead of the twenty-five due to chance, then, surprisingly, we should only expect to find among that one hundred "about 33 [statistically] significant studies ... and a 30% chance that there would be 30 or fewer!" Here's why: The scattergun variance that arises simply from chance would mask most of the extra correct calls. This fact would remain in force even if the responders were picking up their extra hits through hidden radio receivers rather than psi! It's just what happens with the statistics of phenomena that have low power. [...]

Well, could this 37 percent success rate be due to the "file drawer"? Hardly. Honorton's estimate required fourty-six unreported chance-level experiments for each of those in the meta-study, including those that themselves gave no significant support for the paranormal hypothesis. It seems highly unlikely that such a trove of dull experiments exists [...] Nor were the results due to an excessive contribution from a few specialist parapsychologists doing so many precognition studies that their non-scoring rivals were swamped. Strikingly, if all the investigators "contributing more than three studies are eliminated, leaving 33 investigators, the combined z [number of standard deviations found] is still 6.00" - with an associated probability of chance coincidence of somewhat more than one in a billion.

The individual effect sizes were all over the place, so Honorton and his coauthor, Diane C. Ferrari, unceremoniously threw out all the studies with unusually large deviations from the mean. [...] "Outcomes remain highly significant. Twenty-five percent of the studies (62/248) show overall significant hitting at the 5% level." Maybe the quality of studies explains the persistance of apparent anomalies? [...] if anything, the significance of the results climbed as quality improved. [...] What's more, the "effect size" had persisted over more than fifty years. This measure compensates for the different sample sizes in various studies: technically, it divides the z score by the square root of the number of trials in each study.

-- Damien Broderick, Outside the Gates of Science

Would it really surprise anyone here if, say, 10 percent of parapsychologists are either rigging experiments, hiding negative results or falsifying data? 20%?

Thirty-seven percent.

What would be the incentive? Forging results for highly public performances that allowed you to make money off people, sure. But for results published in obscure journals, when even academics in well-respected fields may need to fight tooth and claw for their next yearly funding? In a field that won't even get you the respect of most other academics, and might very well ruin your scientific reputation? Trying to prove a view that doesn't have powerful ideological backers pouring money into it the way creationists do? And with the number of fake researchers apparently staying roughly even for a period of fifty years, looking from the way the effect size hasn't changed?

And with the number of fake researchers apparently staying roughly even for a period of fifty years, looking from the way the effect size hasn't changed?

That right there is a really good point I didn't think of. As for motive, my impression is that a lot of parapsychologists are trying to demonstrate the truth of beliefs that are incredibly significant to them-- their new age spirituality is at stake. For that matter, if they've dedicated their lives to the subject. If there are no psychic phenomena they have literally spent their lives studying nothing. You might as well ask why theologians never come up with arguments disproving the existence of God. But your point about consistency makes this all moot. I'll check out the book.

why theologians never come up with arguments disproving the existence of God

Well if they do they get called philosophers of religion instead...

What would be the incentive?

To get more funding for their work, more fame within the parapsychology community, and to make it more likely that the world at large will realize the truth via "fake-but-accurate" experiments. Some parapsychologists pay for their own experiments, using resources garnered from a "day job" in some other field, but many rely on donations from wacky psi-enthusiasts (people who also get excited about ghosts, "subtle energies" and so forth), or selling psi-controlled meditation lamps. Many others think that it's critically important for mainstream funding sources to provide grants to parapsychologists (such as themselves) to do the work they find interesting and important.

Under those circumstances, a psychic believer could come up with all sorts of justifications:

I have to publish these "fake but accurate" experiments to convince others of the effects that I KNOW are really there, and thus gain enough resources to get definitive proof. After all, surely those dishonest skeptics and materialists (who regularly misrepresent the existing literature, and deceive the broader scientific community about the great work done in parapsychology) are doing the same thing, and if only one side 'enhances' its data then the truth will lose out.

Honorton's estimate required fourty-six unreported chance-level experiments for each of those in the meta-study, including those that themselves gave no significant support for the paranormal hypothesis.

Note that this is a bogus calculation: it says that if there was no publication bias, so that unpublished studies were just as likely to show positive results as published ones, then adding the stated number of chance studies would "dilute" the results below a threshold significance level. But of course the whole point of publication bias is the enrichment of the file-drawer with negative results. See this paper by Scargle. You need far fewer studies in the file-drawer given the presence of bias. Further, various positive biases will be focused in the published literature, e.g. people doing outright fraud will normally do it for an audience.

The number of studies needed also collapses if various questionable research practices (optional stopping, post hoc reporting of subgroups as separate experiments, etc) are used to concentrate 'hits' into some experiments while misses can be concentrated in a small file drawer.

Parapsychologists counter that the few attempts to audit for unpublished studies (which would not catch everything) have not found large skew in the unpublished studies, but these inflated "fail-safe" statistics are misleadingly large regardless.

"Honorton's estimate required fourty-six unreported chance-level experiments for each of those in the meta-study, including those that themselves gave no significant support for the paranormal hypothesis."

Why is this at all unlikely? This is a 52 year span of time, and who knows how many times each of these (only 62) 'scientists' ran the trials or tweaked the procedure before they decided they had a set of data worth submitting. Who knows how many people looked for these phenomena, didn't find them, and gave up without submission? Even without outright fraud (which I wouldn't doubt), people lie to themselves. I've worked with scientists who had evidence that their previously obtained results were bunk and submitted them anyway... 'maybe the retest was flawed...' The significant effect that was found may just be the threshold at which an investigator needs to see (or fake) results to submit a paper. There's the answer to the question Allan originally posed...

Also, on another note, not all 'forced choice' tests are conducted in the same way. Some of them involve the person looking at the card being in the same room as the guesser, and well, it's not hard to imagine ways of getting a score above chance like that.

Why is this at all unlikely? This is a 52 year span of time

309 times 46 is 14 214, which divided by 52 equals approximately 273 unpublished studies per year. I haven't seen any figures on how many studies were conducted for e.g. a specific experimental paradigm in psychology during that time, so I can't say for certain how plausible this is or isn't. It does sound a bit high considering that parapsychology hasn't exactly been the best-funded field around, though it might have had more money in the 1930's. Does anyone have numbers?

I'm not saying there were 14k unpublished completed full studies, I'm suggesting that what got published was already biased. There is room for selection bias at every level of a study, including which trials and which methods are finally taken, written up, and submitted. If the 'scientists' are trying to prove that psi exists, they can find it, one or another. Fraud isn't even required, just wishful thinking. The consistency of the effect is interesting, but may only be measuring the psychological phenomenon of deliberate self-deception.-- ah we've discovered the threshold deviation from chance at which people will believe their own crap hasn't been tampered by their own meddling.

Think about the alternative explanation: If the forced choice test is run properly- the subject guesses which order 5 symbols in a 25 card deck will appear before the deck has been shuffled. The deck is then shuffled by machine (or associate) in a different room, and the order of the cards are examined. Now, how do you propose the subject is entangled with the card shuffling machine and deck, without violating current physical law, such that he can predict the order? This is magical thinking, with no basis in reality as we know it. Unless there is a pattern in the card shuffling machine and some people are very aware of it due to practice with it... but that is hardly psi.

Think about the alternative explanation

I'm not saying that psi must be real, only that it seems to merit a closer look than most people in this thread have been implying. Yes, it does seem rather unlikely that psi would exist, which is why I'm still undecided myself. But the fact that we can't come up with any physical explanation for it doesn't mean that it couldn't be real. As Yvain pointed out, Newton's theories may at the time have seemed like magical thinking as well. There could be some physical mechanism we're just not aware of, but which the brain has nonetheless evolved to take advantage of.

Or then it might just be a sign of our statistical methods being flawed, made worse by psi researchers being insufficiently rigorous in their methods.

[-]LauraABJ
6 points