## A Boost For Quantum Reality 241

Posted
by
Soulskill

from the superposition-of-super-positions dept.

from the superposition-of-super-positions dept.

Eponymous Hero sends this excerpt from

*Nature*:*"The philosophical status of the wavefunction — the entity that determines the probability of different outcomes of measurements on quantum-mechanical particles — would seem to be an unlikely subject for emotional debate. Yet online discussion of a paper claiming to show mathematically that the wavefunction is real has ranged from ardently star-struck to downright vitriolic since the article was first released as a preprint in November 2011. ... [The authors] say that the mathematics leaves no doubt that the wavefunction is not just a statistical tool, but rather, a real, objective state of a quantum system."*
## well, actually... (Score:5, Funny)

it is, and it isn't.

## Re:well, actually... (Score:4, Funny)

If you apply fuzzy logic, then it uniformly half-is.

## Re: (Score:3, Interesting)

Isn't there a way on slashdot to block "funny" comments? Those years old "jokes" littering almost each science-related thread have no value at all for me.

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you are all a bunch of half wits

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the wavefunction is not just a statistical tool, but rather, a real, objective state of a quantum system.

I'm afraid the answer is more complex than that: unfortunately, the wavefunction has an imaginary part, stopping it short from getting real.

## Elephants! (Score:5, Funny)

the mathematics leaves no doubt that the wavefunction is not just a statistical tool, but rather, a real, objective state of a quantum system.

If that's the case, I would suppose that wavefunctions have wavefunctions.

## Re:Elephants! (Score:4, Funny)

It's turtles all the way down!

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Fun fact: it's perfectly possible to model a planet based on turtles all the way down. Put one turtle into space. Put another underneath it in a specular position. Gravity keeps em together, each one is over the other. Put other turtles around them in all directions. Voila', the turtlesphere.

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That sounds like a hell of a brunch.

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## just add "quantum" to the patent... (Score:2)

He also says that Philip Taylor Kramer is stealing his thoughts.

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It's turtles all the way down!

Uhm.. yeah. Sometimes I get my elephants and turtles mixed up.

## Re:Elephants! (Score:5, Interesting)

the mathematics leaves no doubt that the wavefunction is not just a statistical tool, but rather, a real, objective state of a quantum system.

If that's the case, I would suppose that wavefunctions have wavefunctions.

Yes. That's known as second quantization.

## Emotional debate (Score:4, Insightful)

> The philosophical status of the wavefunction [..] would seem to be an unlikely subject for emotional debate

Well not to me. I guess any subject a given amount of people put lots of effort in can arise emotional debates. *Especially* if the subject in question is discussed philosophically.

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The Flat Earth debate only started in the 1800s, until then people had believed in this globe thing.

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Sailors heavily relied on the idea the world was a globe (it lets you measure distance on the open seas with no frame of reference) and it's a handy concept to have in deserts for much the same reason. By the middle ages (and even by the Classical era), a lot of art referenced a globe and that means even those with no direct experience or use for a globe would be aware of it by popular cultural reference.

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The idea and even proofs of a round earth were documented in ancient times, well before the European medieval period. At least one Greek thinker actually measured the differences in shadow between Greece and Egypt and derived a fairly close to realistic value.

Of course, at the same time, the medieval period produced what are generally called T and O maps, which were basically a depiction of the Earth with one landmass, surrounded by a ring of Ocean (the "O" part) and three major water masses (Nile, Mediter

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The scientific community has it's own form of burning at the stake. Today, it's done by cutting off funding.

## Arxiv.org link (Score:5, Informative)

http://arxiv.org/abs/1111.3328v2 [arxiv.org]

http://arxiv.org/pdf/1111.3328v2.pdf [arxiv.org]

## It makes sense when compared to string (Score:2)

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What is the thing that is vibrating? The equation E=MC^2 seems to indicate that matter and energy are just two expressions of the same thing. I acknowledge that my confusion "might be" just my inability to imagine nothing vibrating. That doesn't sound right. I mean "nothing" vibrating. See there, I have done it again. No matter how I say it it only makes sense if something is vibrating. If it is a th

## Re:It makes sense when compared to string (Score:5, Interesting)

I am not convinced that the particles regarded as fundamental actually are. I'm not even completely convinced that "particles" at that level even exist in the normal sense, since we know interference patterns exist when the gap is in time rather than in space. That makes no logical sense when using a corpuscular model.

It is my suspicion (IANAQMPBTIBO) that in precisely the same way that matter is merely energy that has "condensed" and entangled, particles are merely waves that have "condensed" and entangled. This is based on the fact that fundamental particles of the same type are totally interchangeable and no two particles of the same type are in the same state. To me, that does not appear distinguishable from saying that a single wave appears to be every particle of that type, since that would give you what is observed without having to have any new or excessively complex physics to explain it.

If that is correct, then neither space nor time are particularly important in QM. Which has been theorized by better minds than mine. You would be able to map everything into waveforms and not need spacetime for them to exist in. Rather, spacetime would be one way an observer could interpret those waveforms - it would be subjective, not objective. The waves themselves would be the only "reality". Again, there's a branch of QM based on just such a notion.

To answer your question as to what is "vibrating", in this line of thought there wouldn't be anything TO vibrate, per-se, no time for it to be vibrate in and no space in which the vibrations could take place. You'd simply have a multidimensional waveform where if you made some axis space and another one time, you could treat it as though something was vibrating. In practice, though, it would be a static n-dimensional waveform whose existence was logical rather than physical.

I like this particular branch of QM, as it means physics is a branch of mathematics, a specific group with specific properties and specific operations, and that the universe is a specific set of functions that wholly reside in that group. It makes maths the "ultimate" reality, which means these sorts of philosophical musings about the world can be answered through mathematical analysis (although maths permits that answer to be rigorously undefined).

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I am not convinced that the particles regarded as fundamental actually are.

This is in fact an older problem than people expect. Ancient Greeks talked about problems with the continuity of space, which lead them to note spacial paradoxes like "Achilles and the tortoise" [wikipedia.org]. One of the proposed solutions to deal with issues of the infinitesimal was to assume that objects are all made of very small particles called "atoms", which were not able to be split any further. Scientists later adopted the word when they discovered that there were indivisible pieces of chemical elements which

## Yet another no-hidden-variables theorem (Score:3, Interesting)

The paper is related to Einsten-Podolsky-Rozen (EPR) paradox and the related "hidden variables" hypothesis which AFAIU states that there are some hidden variables apart from wave function that we can not observe directly. However, under some assumptions it can be proven that their existence affects some statistical properties of a particular type of measurements and therefore can be experimentally tested. One of such theorem was Bell inequalities published in 1964. In the Nature paper in question authors prove similar "no-go" theorem but under different assumptions. To quote:

The result is in the same spirit as Bell’s theorem[13], which

states that no local theory can reproduce the predictions

of quantum theory. Both theorems need to assume that

a system has a objective physical state such that prob-

abilities for measurement outcomes depend only on .

But our theorem only assumes this for systems prepared

in isolation from the rest of the universe in a quantum

pure state. This is unlike Bell’s theorem, which needs

to assume the same thing for entangled systems. Fur-

thermore, our result does not assume locality in general.

Instead we assume only that systems can be prepared

so that their physical states are independent. Neither

theorem assumes underlying determinism.

There is, however, another theorem by Kochen and Specker that is not cited in this paper but also does not assume locality. From wikipedia

The essential difference from Bell's approach is that

the possibility of underpinning quantum mechanics

by a hidden variable theory is dealt with independently

of any reference to locality or nonlocality, but instead

a stronger restriction than locality is made, namely

that hidden variables are exclusively associated with

the quantum system being measured; none are associated

with the measurement apparatus. This is called the

assumption of non-contextuality.

It would be interesting to know what would be the relation of results from the paper to that theorem...

## If the internet has taught us anything (Score:5, Insightful)

Its that there's no such thing as an unlikely subject for emotional debate.

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## Thought (Score:4, Interesting)

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Indeed, the problem with reversing time is that you suddenly have to change physics to handle the fact that the time has already been used. I remember Einstein expressing the view that we get 3 dimensions of space which can be reused and one dimension of time which can't be reused. And physics generally works and the equations are written for that reality. If suddenly, you can reused time and particles can go back and potentially interfere with themselves, then a ton of work would have to be put into making

## Summary (Score:5, Informative)

The article confused me greatly so I read some of the arxiv preprint linked above. Here's the idea and context as I understand it. I've included some basic quantum background since most people here don't have it.

* Intro to wavefunctions via an example. Electrons have a property called "spin" which has two states, "up" or "down". These can be measured in, for instance, the Stern-Gerlach experiment [wikipedia.org] where those electrons with spin up are deflected up by a magnetic field and those with spin down go down. The wavefunction corresponds to a list of the probability of each outcome occurring. The probabilities evolve through time via the Schrodinger equation which allows predictions to be made. One might prepare an electron where its spin wavefunction corresponds to the list [1/3, 2/3], so 1/3 of the particles go up and 2/3rds go down. [I've oversimplified; wavefunctions are actually elements of an abstract Hilbert space and complex-number amplitudes are used instead of real-number probabilities. I love Hilbert space but it's too much to explain here.]

* Spin is not a classical property. One can measure spin "left" and "right" in addition to "up" and "down" by rotating the Stern-Gerlach (SG) device mentioned above and measuring left/right deflection. Suppose you run a stream of electrons through an up/down SG device which gives 80% of them "up". You then run those "up" electrons through a left/right SG device--it will always come out with 50% "left" and 50% "right". Even more strangely, if you then run the "left" electrons through another up/down SG device, the probabilities will now be 50%/50%, even though you selected only spin up electrons at the first stage so you'd expect 100%/0%. The act of going through the left/right device altered the spin up/down state somehow.

* Hidden variables. Perhaps the electrons above have definite "spin vertical" and "spin horizontal" properties before the experiment starts. The act of going through a device must change the other property, though everything might be deterministic if there is some further hidden property controlling which electrons have their spin up/down states altered in which ways by passing through the "left" SG device. The alternative is that there are no definite properties which determine the wavefunction; the wavefunction is all there is, reality is somehow fundamentally probabilistic, and the wavefunction is "real" instead of a statistical construct.

* Bell's theorem. Suppose spin up/down and spin left/right are definite properties and some hidden variables explain the above results. Using entanglement (which I'll leave undefined) and the assumption that information cannot travel faster than light, one can measure both the spin left/right and spin up/down values of a particle before the hidden variables have a chance to act (note: they might act in a very bizarre, perhaps even non-deterministic, manner, but we get to measure things before they have that chance). This gives a testable prediction which differs from quantum mechanics. If the experiment is performed, the "definite property" theory does not predict reality while the use of wavefunctions does predict reality. This is strong evidence for the reality of wavefunctions, though it's not completely conclusive.

* The paper. It derives Bell's fundamental contradiction from fewer assumptions. In its own words,

The result is in the same spirit as Bell's theorem, which states that no local theory [i.e. one without faster-than-light communication] can reproduce the predictions of quantum theory. Both theorems need to assume that a system has a objective physical state L such that probabilities for measurement outcomes depend only on L. But our theorem only assumes this for systems prepared in isolation from the rest of the universe in a quantum pure state [e.g. a particle measured as spin "up" right after the SG experiment above]. This is unlike

## Re:Summary (Score:4, Insightful)

My own take as a physicist who knows a bit about this stuff can be found here: http://www.tjradcliffe.com/?p=621 [tjradcliffe.com]

The important fact is at the end: "That is, 'Preparing a photon in the same quantum state will sometimes result in photons in different physical states' does not imply 'Preparing a photon in different quantum states will sometimes result in photons that are in the same physical state'. The former proposition is the statistical interpretation. The latter is the assumption that the authorâ(TM)s argument depends on."

Since the author's assumption has nothing to do with the statistical interpretation, their argument says nothing about the statistical interpretation.

## Re:Dammit... (Score:4, Informative)

As I said I love Hilbert space, so your comment is enough motivation for me to write up a brief explanation.

The n-dimensional Hilbert space is the collection of length-n lists of complex numbers. One can add these lists and scale them, so for instance [1, i] + [2, 1] = [3, i+1] and 2*[i, -1] = [2i, -2]. Physically, each component of the list corresponds to a possible experimental outcome. More specifically, the probability of the outcome corresponding to the ith component is the square of the magnitude of the ith component. For the electron spin up/down experiment I talked about the wavefunction [1, 0] gives a |1|^2 = 100% chance of measuring spin up (and 0% chance of measuring spin down; this is called a pure state). [sqrt(1/3), sqrt(2/3)] corresponds to a 1/3 chance to measure spin up and 2/3rds to measure spin down. You may wonder why the magnitude-squared business is used at all (why not just keep track of the probabilities?) which is where the complex numbers come in to play. The state [sqrt(1/3), i * sqrt(2/3)] has the same experimental outcomes given this single measurement as the previous state, [sqrt(1/3), sqrt(2/3)] but it is fundamentally different from it since the two components are "out of phase". More elaborate experiments can detect the difference. In this case it turns out the result of the spin left/right experiment is encoded in the phase difference between the two components.

Hilbert space comes with an important operation called an inner product, which I'll denote by the term "dot". It can "single out" the entry at a particular position in a list. For instance, by definition [1, i] dot [0, 1] = i, singling out the second component. The operation is extended to more general lists on the right-hand-side by rules I won't discuss, and it has a physical interpretation in terms of probabilities--the magnitude of (A dot B) squared is the probability of measuring a particle with wavefunction A in the state described by wavefunction B, which fits what I said above in light of the computation |[sqrt(1/3), sqrt(2/3)] dot [1, 0]|^2 = |sqrt(1/3)|^2 = 1/3. Note that the sum of the squares of the magnitudes of the entries in the list must be 1 since the experiment will have some outcome with 100% certainty.

One can have infinite dimensional Hilbert space where the lists are allowed to have infinite length. Sequence space is a popular example: it contains [1/1, i/2, 1/3, i/4, 1/5, ...] and [0, 1, 0, 0, 0, ...]. We often restrict ourselves to lists where the sum of the magnitudes squared are 1 since these are the only physically meaningful wavefunctions, giving the so-called projective Hilbert space. [1, 1, 1, ...] is certainly not in that space since it has infinite sum-of-squares. Actually, [1/1, i/2, 1/3, i/4, 1/5, ...] doesn't work here either, but sqrt(6)/pi * [1/1, i/2, 1/3, i/4, 1/5, ...] ...] fails particularly badly since it cannot be scaled to an element of projective Hilbert space as we were able to do with the other list, so we don't allow it in regular Hilbert space at all. Any other lists that have infinite sum-of-squares are similarly excluded. The inner product is extended in a natural way to infinite lists. That's all the structure one requires.

doeswork. (There's a beautiful proof using Parseval's theorem.) [1, 1, 1,I should note that Hilbert space is more often defined as an abstract vector space over the complex numbers equipped with a positive-definite sesquilinear inner product which is moreover Cauchy complete with respect to the induced norm. Projective Hilbert space is usually defined as projective equivalence classes over a Hilbert space with semi-canonical norm-1 representatives. My definitions are equivalent, assuming the axiom of choice (everybody does), and they're obviously more accessible (though it's much less pretty IMO). I should also mention that wavefunctions and elements of Hilbert space are usually written with the bra-ket notation and as sums of pure states (as the paper does); my notation is from Python and was chosen considering the audience.

## of course it's real... (Score:2)

Of course it's real. There isn't an imaginary term in the wavefunction equation.

## First step (Score:2)

I intend to patent the direct manipulation of the quantum wave function, which will, among other outcomes, be the basis for my infinite improbability drive.

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this needs an insightful mod at least.

## Re:Heh (Score:5, Interesting)

It certainly knows.

Itknows, but you don't. You don't because you haven't measured it yet. And until you measure it, the answer is not the simplified version of the cat being dead and alive at the same time, but that there's a probability it's dead, and a probability it's alive, but it'll never be more than probability until you actually confirm it. Once you confirm it by measurement, the probability of one state goes to one, and the probability of the other state goes to zero.This goes back to the age-old question: If a tree falls in a forest and no one is around to hear it, does it make a sound? It certainly makes a noise, but does it make a

sound?If there's nothing to observe reality, does it still exist? That's the essence of Schrodinger's cat.

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If there's nothing to observe reality, does it still exist?

Yes.

Moving on.

I said

moving on!## Re:Heh (Score:5, Insightful)

I've never understood how some people can be so dogmatically sure about the existence of an objective reality. Not to say there isn't one. but I've actually heard some people claim that 100% of their own experience supports an objective reality external to themselves. That would imply that a persons dreams, hallucinations, emotions, being fooled by optical illusions, and other such things were all proof of something about the nature of that reality. A little bit of introspection here soon shows that, however convinced you are of there being an objective reality or however certain you are that your experiences support it, you simply can't, in reason, claim that every single experience you have proves something about the nature of that reality.

Hell, most people don't learn that their 'self' is running on a physical substrate normally called a brain, until they are at least eight to ten years old. All those other experiences up until then certainly didn't reveal much about the underlying nature of any objective external reality until then, did they? That's a pretty damned important fact about the supposed objective external reality, considreing that brain will have litterally trillions of sensory experiences before it ever even possibly gets to a state where it can become aware of its true nature, and then only if it grows up in a society that has learned modern medicine.

It amazes me still that so many people can think kicking a stone really refutes Bishop Berkeley.

The evidence that QM is more than a mathematical trick mounts. It's worth noting that, at the beginning of the 20th century, most scientists weren't at all sure atoms were real and not just a mathematical convenience. It took Einstein's paper on Brownian motion to convert many scientists to the viewpoint that atoms were more than a convenient simplifying model. If this work holds up as well as Einstein's, it may be equally respected in the judgment of history.

## Re:Heh (Score:5, Interesting)

Try this as a thought experiment. Imagine your brain and your DNA scanned into a computer. This is used to generate a simulated you. This simulated you is placed in a simulated room in which all the known laws of physics are simulated to a high degree of precision.

You are placed in an identical, but real, room. The two rooms are connected via a terminal (or, in the copy's case, a simulated terminal).

You and the simulated you can ask for any scientific equipment that can fit into the room. Both of you can conduct whatever experiments you like. The only requirement is a unanimous agreement between you, your copy and those running the experiment as to which of you is physical and which is virtual.

If no observation, experiment, or set of experiments, exists that can prove which is real, then you cannot prove what is "real" - there'd be nothing so unique to reality that would allow you to unquestionably establish that something belongs to reality and not to something else. If, however, you CAN through experimentation reach a unanimous verdict, then an objective reality is provable.

It is my opinion that it is the first case that would turn out to be true.

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That's because this particular experiment needs communication and agreement between simulation and real world.

Try something simpler.

Put a complete simulation of an existing human in a simulated environment and tell him "hey you are simulated, you feel anything different from your memories"?

Then it doesn't matter what the speed of the simulation is, an accurate one will have normal speed from the point of view of the simulated being: it's another timeline.

My objection to this experiment is that it doesn't pr

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With magic and woo, all things are possible.

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The copy will have additional breakdowns specific to the hardware it's running on (power failures, etc.), which will not be evidenced by the non-copy.

I think that Joel Spolsky would call this the "Law of Leaky Abstractions".

## Re:Heh (Score:4, Funny)

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It would be easy to distinguish the real you. It is the one that would actually exist, since the entire premise of somehow scanning your brain and DNA into a computer is not possible. This scenario is like the question of "If God is all powerful, can he make a rock so heavy that he can't pick it up."

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Request a copy (or as many as is required) of the computer. Run it. The simulated version will run slow.

However this doesn't imply that objective reality is provable, just that computers can't simulate reality perfectly.

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fuck.## Re: (Score:2)

This simulated you is placed in a simulated room in which all the known laws of physics are simulated to a high degree of precision.

How high a degree of precision? Do you know the "correct" laws of physics ahead of time, such that you could perform tests which required a greater degree of precision than the computer is capable of, and then when the results don't match, know which results are "wrong"?

Essentially if the computer could replicate reality to a degree great enough that no measurements could demonstrate whether you were in "reality", then no experiments could prove which of the two of you are "real". Also in this example, y

## Re:Heh (Score:4, Insightful)

Given that I've spent the majority of my life working with computers, I've come to accept reality as just another theory. Does the OS know it's inside a virtual machine ? (without the hypervisor intentionally making itself known) How can any person know, with absolute certainty, that they're not a brain in a jar, being fed simulated input ? How can we even know we're a brain at all ? For all I know, my entire existence could be a work of fiction, the Internet could be a fabrication of my mind, along with all its inhabitants.

The only thing we can reasonably assume, is that

thoughtexists.(and yes, I think the best psych/philosophy profs were the ones who dropped acid on a regular basis :)

## Re: (Score:2)

Given that I've spent the majority of my life working with computers, I've come to accept reality as just another theory. Does the OS know it's inside a virtual machine ? (without the hypervisor intentionally making itself known) How can any person know, with absolute certainty, that they're not a brain in a jar, being fed simulated input ? How can we even know we're a brain at all ? For all I know, my entire existence could be a work of fiction, the Internet could be a fabrication of my mind, along with all its inhabitants.

The only thing we can reasonably assume, is that

thoughtexists.(and yes, I think the best psych/philosophy profs were the ones who dropped acid on a regular basis :)

If you really think the OS or any other program knows anything about itself, you need help. The OS and programs are just electrons 0s and 1s. There is no sentience.

You can be reasonable sure that you exist if you can think (I think, therefore I am), because for thought to exist, some "thing" has to have the thought.

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That's just solipsism. Logically sound, but unfalsifiable and practically useless.

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That's just solipsism

He didn't go that far. Had he gone that far, he probably wouldn't have posted here.

Remember that old joke? A philosophy professor walks in on the first day of class and announces "Before we begin, I just want to say that I'm a solipsist" A girl in the back stands up and exclaims "Thank goodness! I thought I was the only one!"

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The only thing we can reasonably assume, is that thought exists.

Aren't you assuming

assumption existsthere? Okay, assumption might be a subcategory of thought. So, reasonably, we can think thought exists. We're also thinking that "reasonably" means something. Well,reasonis a category of thought too. So most of the "onlyreasonableassumption: that thought exists" is saying not much more than "We think we think." Okay. But notice what'snotabout thought or it's subcategories in that sentence: "We." So presumably we can reasonably assume - or more than assume - "we."## Re: (Score:2)

Cogito ergo sum.

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The only thing we can reasonably assume, is that thought exists.

And this was the basis for Descartes famous "cogito ergo sum". The first thing he could say is that, even if he doubted his own existence, the act of doubting meant that his thoughts existed, which meant (as best as he could figure) the thoughts must have a source, and so therefore he existed in some form, thinking thoughts.

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Rather than spend the majority of your life working with computers to come to your "conclusion" you could have just read Descartes.

It would have saved you a lot of time -- time you could have spent catching up with a few hundred years worth of philosophical thought.

+3 Insightful for Cogito ergo sum ... amazing.

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I'd imagine that from the point of view of any die-hard extremist atheist, it becomes really really hard to make fun of religious nuts if your beloved science isn't even based on the assumption of the existance of an objective reality.

Not really - I make fun of religious nuts constantly, and have no problem with the possibility that objective reality - if it exists at all - is unknowable.

I used to have a problem with it in my early teens, but after significant years of mellowing (and significant amounts of LSD in those years...) it really doesn't bother me at all. I actually find some aspects of the philosophical angles to it quite beautiful, and others absolutely boring.

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I think the real trouble and problem comes up considering consciousness. The eye and brain are analogous to a camera with a lens, a CCD and a CPU processing images. A really advanced CPU could even start describing in words what it is looking at. But at no point does the camerathe image it is capturing. That's the difficult issue with sentience. What is this ability to experience, as opposed to just mechanistically reacting by processing inputs and outputs? Why are we not just human robots, ac

experience## Re: (Score:2)

That's the difficult issue with sentience. What is this ability to experience, as opposed to just mechanistically reacting by processing inputs and outputs?

I'd say there really is no difference. Consciousness, as far as we can tell is basically just a side effect of the processing that's going on. It may be possible to construct something that doesn't have this side effect (the "sleepwalking robot" from your example); but whether it is or isn't, it seems that at least the way WE'VE evolved, this side effect happens.

While we can't say with any certainty which other animals (if any) experience consciousness (and to what degree - it may well be that different l

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Yeah, I'm fairly atheist myself, it is the materialist side that I'm questioning. The thread is sorta, we might be living in The Matrix, and how could we tell? How do we know our memories are not implanted, as you say. That's what makes consciousness itself quite different, and not easily reducible to being a "side effect" of matter. Descartes sorta did this questioning, he thought that everything could be The Matrix and his senses could be entirely a simulation, the whole reality fed to him as a simulation

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But the awareness itself, the feeling of existing, simply knowing you exist, that isn't reducible to anything else.

I'm not entirely sure about that. The awareness, the feeling of existing, and so on could just an emergent property of the matter/energy patterns of our brains (or anything else, such as being in a simulation). The problem comes with trying to rationalise this to oneself. Since you feel that you are aware and you are doing the analysis of it, you tend to accept/assume that that "you" that's doing this analysis/thinking must be something special and unique in and of itself. This however has no rational b

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My point is, I think a highly sophisticated enough robot could function at 100% human level. Therefore humans as we are, don't neeeeed to be sentient to be humans.

My point is, nature could have humans doing human stuff, like chimps and dogs do their stuff, without humans needing any sentience, or anything needing any sentience -- everything could just process data inputs and run sophisticated behaviour programs. As I said, a sophisticated camera could process images and identify objects and speak words.

Yet

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But there is essentially no reason to

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I just have to send the link here... It's so damn funny, and yet the only people able to appreciate it are probably those attending discussions like this :-)

http://www.smbc-comics.com/index.php?db=comics&id=2535 [smbc-comics.com]

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I've never understood how some people can be so dogmatically sure about the existence of an objective reality.

Because not all religion requires a deity.

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That would imply that a persons dreams, hallucinations, emotions, being fooled by optical illusions, and other such things were all proof of something about the nature of that reality.Are they not? Do dreams, hallucinations, emotions, and optical illusions not manifest themselves physically? The fact that I dreamed last night proves that my brain entered REM sleep. The fact that I might see the same color gray as darker or lighter based on the background proves that my eyes are not densitometers.

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The reason people are dogmatically sure about the existence of objective reality is that they misunderstand the options. They think their options are either:

A) You have an "objective reality" that is knowable by people, and I can (more or less) trust my senses and experiences. When I see a rock, the rock is really there.

B) You only have "subjective reality", which means that everything is as true as I believe it to be. We all might be in the Matrix, and if you see a rock, it might not be there. If you

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I've never understood how some people can be so dogmatically sure about the existence of an objective reality. Not to say there isn't one. but I've actually heard some people claim that 100% of their own experience supports an objective reality external to themselves

I have thought about this quite a bit, and the conclusion that I have come to is that reality is at once objective and subjective. There does indeed seem to be an objective reality outside of our consciousness. Two people can observe an object and generally come to an agreement about it. However, they are both experiencing viewing that object subjectively. They have to observe it to be aware of it at all, and observation and experience are always subjective. So while there may be an objective reality,

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I've never understood how some people can be so dogmatically sure about the existence of an objective reality.

There's no need to have an objective reality, but having one makes so many other things much easier (like why would I even bother discussing this with you if you don't really exist?) Think of it like a (very useful!) working hypothesis.

## Re:Heh (Score:5, Informative)

No. Well, maybe for the cat, we're not able to do the experiment to tell.

But in the equivalent test using a photon in place of a cat and orthogonal polarization states in place of dead or alive, the photon most certainly does not "know" what state it is in.

This is the essence of Bell's inequality and the fact that there is no local hidden variable theorem compatible with the results of QM.

Tim.

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It's about what is, not what you know. That is, it's not that you can't know, say, a particular property due to some limit to our ability to measure it -- it's that the property

doesn't havea definite state.Why are people so desperate to believe that they live in some Newtonian billiard-ball universe? Hell, that didn't even work for Newton!

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The cat isn't really both alive and dead. It's either still alive or it died. It certainly knows.

>

That's assuming there is a cat in the box to start with.

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The only real loser is religion, whic presupposes just the one timeline. But then, religion has a long history of losing out to science and changing its teachings accordingly (like cockroaches, the memes don't die, they just adapt), so even that is unlikely to change if or when the multi-world hypothesis is proven.

Not sure why you believe that religion pre-supposes one timeline. Certainly, there are adherents of religions that take that viewpoint, but all religions usually do is say: there's this god over here and he or she or they say "Hi, I'm God or some really powerful entity. I have some stuff to say and you probably should listen." Sometimes there is an "or else" clause. That or I missed where the Prophet Elijiah discussed wavefunctions or timelines in the Bible.

Most of the major monotheistic religions these

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The question is, which universe do you inhabit?

Ugh. Why people think this is somehow better than collapse interpretations I'll never know. I have a very hard time accepting that my coffee mug, while just sitting on my desk, is (as many worlds interpretations insist) spawning zillions of universes near continuously is positively ridiculous.

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The question is, which universe do you inhabit?

Ugh. Why people think this is somehow better than collapse interpretations I'll never know. I have a very hard time accepting that my coffee mug, while just sitting on my desk, is (as many worlds interpretations insist) spawning zillions of universes near continuously is positively ridiculous.

I think it might be easier to just have a single quantum reality. That coffee mug is a quantum object, though we only know its quantum state very roughly, so roughly that it looks like a classically-described object. There is no decoherence, no picking of universes. There are just quantum interactions: in the case of a "decoherence event", you've just got a quantum interaction between one relatively-well determined quantum entity (the experiment) and a much larger undetermined quantum entity (the rest of th

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You'd think that rational thought would cure you of setting up straw-men and knocking them down. Even many ultra-conservatives don't speak at that level. They're usually quite familiar with the value of science and technology, the real difference is just how they perceive it as affecting their worldview.

## Re:I get it now (Score:5, Interesting)

actuallysmeared out or does it exist at one point and we're just limited in our observations of it (aka a "hidden variable"). These days the argument is whether the (Copenhagen interpretation) wave function actually exists or whether it's a mathematical artifact of a different theory, such as Everett's "Many Worlds" interpretation. Personally I go with Everett, but for philosophical/anthropic arguments rather than anything testable at the moment.## Re: (Score:2)

The problem with the many worlds interpretation is that if you flip a coin and it comes up heads, there must also be a world where the coin came of tails.... and one where it came up donkey, and one where the universe instantaneously collapsed, and one where the coin wasn't there at all, and one where the coin was exactly the same but one atom was at a slightly higher energy. And in all these more then infinite worlds, there would be events that require equally many universes to take on alternatives. Observ

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"Personally I go with Everet..."

I do as well but i 'think' the answer lies in the discrepancy of gravity from 'expected' values in the equations of physics by a slight hundred-twenty orders of magnitude. I have often read in the past several years that this could be due to gravity leaking off our brane(m theory) but it'll be a while before i can explore the theories mathematically for myself.

I have a multitude of lectures to watch online and learn about the various mathematical tools and techniques to see w

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If the wave function has an effect then it what way is it not real? Maybe its the mathematician in me but if reality can only be understood mathematically then I have no problem with that, thats just a problem with our imagination. I have always thought the divided universes interpretation of quantum physics multiple states was reading too much into things, a bit like during the steam age everybody wanted to interpreted things in terms of steam engines, thats useful, but the model implies things which the pure maths itself doesn't.

Think of probability distributions. If you throw a die and don't look at the result, you don't know which of the possible results happened. However you know that if you throw that die often enough, you know that each result happens approximately the same number of time. Therefore you can assign the same probability to each result, i.e. 1/6 each. But the probability distribution does

notdescribe the current state of the die; the current state of the die is that it shows one of the numbers 1 to 6. It just te## Re: (Score:3)

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The 19th century mechanists that seem to dominate Slashdot can't explain it. Like creationists, they can't handle any science which doesn't conform to their preconceptions.

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Maybe you understand it, maybe the GP does too, but are you saying the photon doesn't go through both slits simultaneously? It's fairly well accepted that a particle evaluates every possible path and the resultant path comes down to the derived probability for each possible end result.

How does this work?

Short Answer: Read up on QED.

Long (and probably incorrect because it's my understanding) Answer:

The way I get my head around this is to say consider everything as a field. The electron field, the photon fiel

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The wavefunction tells you exactly what state a system is in.

Consider a quantum dice. You can perform a roll-operation on it which sets it to a rolled-dice state. You can also perform a result-operation, that also sets the state, each characteristic state of the roll-operation has a value associated with it (1, 2, 3, 4, 5 or 6). You can look at the result without altering the state after the first result is found (it's a projection operator in other words). The first difference with your explanation is that