Quantum Mechanics Involved In Photosynthesis 137
Kristina at Science News writes "We all learn about photosynthesis in school: sunlight in, plant food out. Not well understood is how this process achieves its initial and uniquely high efficiency in capturing the energy of a photon. Quantum mechanics may be at work in the electron transfer process inside chloroplast, giving electrons the chance to consider many paths at once before choosing the best one."
That's Some Mighty Fine Learnin' Kristina (Score:3, Informative)
We all learn about photosynthesis in school: sunlight in, plant food out.
Huh, apparently some of us learned about it differently than others. I seem to recall it having to do with water and carbon dioxide in and some extra oxygen left over?
Also, I think someone beat you to the punch back in 2007 when we covered this story the first time [slashdot.org] and we covered that part about the birds using quantum effects [slashdot.org] in 2008.
Re:That's Some Mighty Fine Learnin' Kristina (Score:5, Informative)
[CO2 and H20 in, O2 and long-chain organics out] is ancillary to the photosynthesis process. Photosynthesis is sunlight in, e- out (plus some ADP-->ATP goodness).
Electrons, then, are the plant food that is used to synthesize long-chain carbons.
I think maybe you never took advanced bio or molecular bio or any other classes that would have covered this more in depth than the simplified HS bio crap?
Re:That's Some Mighty Fine Learnin' Kristina (Score:5, Funny)
It's been a long time since I've taken a biology class, but the way I remember it is the sunlight hits the plant and the plant makes food with it, like tacos. Also, I think some birds fuck some bees or something. It's all very confusing.
Re:That's Some Mighty Fine Learnin' Kristina (Score:5, Funny)
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It's only actually dangerous in Sydney, where you have to wear special hats to stop the crows who also got that talk.
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Photoelectric Effect (Score:4, Interesting)
It's covered in physics, to the extent that photosynthesis and the photoelectric effect are used to demonstrate photons must have momentum. (The law of conservation of momentum requires that the momentum going in equals the momentum coming out, so if the electron has momentum, then the photon must also.)
Way to go, scare away the female (Score:1, Funny)
People like you are the reason geeks never get laid.
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Xylem up.
Phloem down.
Oxygen release.
Oh what fun it would be if I could be a tree!
Or something like that...
Re:That's Some Mighty Fine Learnin' Kristina (Score:5, Informative)
>Also, I think someone beat you to the punch back in 2007 when we covered this story the first time [slashdot.org]
yeah, but about halfway though the article, they finally start talking about the new (post-2007) discoveries and refinements to this idea.
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If I only had points to give you for being so informative...
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Oh man, your post is just precious. Not only do you insult someone's "learnin'" while being obviously wrong, but at the same time you make the "it's a dupe" statement that is necessary in every /. story.
Hint about photosynthesis: photo is from the Greek word phos, meaning "light." So photosynthesis just possibly might have something to do with using, I don't know, light? to synthesize (which means to combine elements into something new).
Sunlight in, elements combine together using energy from that light,
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Calling people names usually will not make them more cooperative. The fact that you were modded Insightful says more about todays /. crowd than about your intelligence. Please rephrase your question in a civilized way and add a compelling argument for going back to the old Slashdot layout to try to convince the editors.
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Hm, I see your point and can imagine your anger. I must say that for me it works well. I like the way it adds older stories to the page when I scroll down. But I have an almost 3 year old Macbook Pro. I can imagine that on slower computers it doesn't work so well.
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you have a point, though the only thing I see causing performance issues is the Beta Index.
I tried to give it a chance, but after about 20 minutes, it had to go.
If the beta index becomes the only way to view slashdot... I'll stop reading slashdot.
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Seventh, the story links no longer change color when I middle-click to open them in another link (a habit I started back in the 90s when traveling to a dial-up nation, which I keep to this day as it allows me to cleanly switch tasks: going from "scanning for interesting stories" to "reading in depth" without switching back-and-forth).
It's annoying because sometimes I'll leave a tab overnight, or occasionally for over a day; when I go back to the home page now, I may end up middle-clicking the story twice if
Srsly? (Score:2)
Now, it is quite interesting that we now might know more about specifically how it does so; but that is slightly different.
Re:Srsly? (Score:5, Insightful)
Unless you doubt the validity of the field of quantum mechanics, then you probably have to acknowledge that it's "involved" in all physical phenomenon. I mean, when you ask for an explanation of a specific phenomenon, you might want to know more about the larger scale interactions and forces, but still, electrons are involved and they're doing stuff. Probably all sorts of quantumy stuff that would blow your mind.
However, it does seem like quantum mechanics would turn up as much more relevant when you're talking about the conversion of light into some kind of energy a living organism can use. When you get down to the level of trying to analyze what happens to an individual photon in the process, I don't know how anyone expected to avoid talking about quantum mechanics.
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I'm still not sure what there is here that wasn't covered by Einstein when the photoelectric effect was first described.
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I dunno. More people seem to be interested when the guy has a magician's hat than a scientist's lab coat.
"Quantum mechanics may be at work" (Score:4, Insightful)
The process involves photons that are absorbed while exciting the energy of molecules OF COURSE quantum mechanics is involved. Coming up next, thermodynamics may be at work in volcanic eruptions.
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All chemistry, most physics (Score:3, Insightful)
Nearly everything involving chemistry is governed by quantum mechanics...
Actually all chemistry is governed by quantum mechanics. In fact practically everything we can explain is governed by quantum mechanics, the only exception being gravity and even then we think it is governed by QM we just have not found the right model. Of course for things that happen at human scale it is often easier to use a continuum-based approximation of QM...but it is still an approximation of the underlying QM.
Re:"Quantum mechanics may be at work" (Score:4, Informative)
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There is a common misconception that quantum computers can solve NP-complete problems in polynomial time. That is not known to be true, and is generally suspected to be false.[24]
'Nondeterministically' guessing the answer won't be enough. There is a class called BPP that concerns those algorithms classically, quantum computing goes further, but might still not be able to solve NP-complete problems fast. You say "an NP problem is one that can be solved in polynomial time", but you either meant that the answer can be checked in polynomial time or that you know P=NP. In the last case large amounts of fame and money are
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While its is arguable that they do a good job explaining it, results that came out about 6 months ago suggest that incoming light can be directed to reaction centers through means of doing a quantum computation for the light to determine where the reaction center is. The ratio of antennas to reaction centers is about 300:1 which would make the photoharvisting step lossy if it wasn't for this quantum computation. The efficiency is well over 95% for the initial light harvisting step.
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I thought this was obvious (Score:1)
It's not about quantum photon absorption. (Score:4, Informative)
I thought this was obvious after learning about photodiodes in electronics class.
It's not about the quantum nature of the absorption of the photon and its conversion to an excited electron state.
It's about the efficient propagation of that excited electron state, once created, from one molecule to another until it gets to a place where it can be used. "Picking the path" in a non-random way, without losing energy in the process, seems to be using quantum weirdness as well.
The more important question (Score:2, Funny)
Is there any way to incorporate string theory, membranes, dimensions, time travel, or wormholes into this explanation? Kaku has some speaking engagements and needs some buzz words along with the usual Star Trek references.
This is just silly. (Score:2)
The article makes somewhat more sense later on, when they suggest that "weird" quantum effects might be involved... but initially the article gives the (incorrect) impression of scientific illiteracy.
Comment removed (Score:5, Funny)
Re:Quantum mechanics may be at work (Score:5, Funny)
You didn't think the Eucharist was made out of wheat by accident, did you? Heathen.
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You just never know where the next creationist is these days. I even heard stories about how they have no toes, but just this square ending on their feet...
Quantum Mechanics (Score:5, Funny)
Don't understand why people make irrational decisions [slashdot.org]?
Quantum Mechanics may be at work.
Don't understand how photosynthesis happens?
Quantum Mechanics may be at work.
Don't understand contradictions in quantum mechanics?
Well, that is because sub-atomic paticles may have free will [slashdot.org]?
Can't we just credit God or something?
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Quantum Mechanics IS God!
Dun, dun, dunnnnn!
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No, we cannot just credit God or something. While I don't begrudge anyone their faith, science cannot admit supernatural explanations, nor can it investigate supernatural phenomena. As soon as you admit something that cannot be measured or even necessarily repeated or even observed, you are throwing out basic scientific process. So go ahead and credit God if you want
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So go ahead and credit God if you want to. I won't tell you that you're explanation is necessarily wrong. Just please don't do so in a scientific context.
I agree with you. But there is sad tendency for people who regard themselves as not religious or spiritual, who might have very little or a lot of scientific knowledge, to disregard ideas that don't lend themselves to scientific investigation as untrue or stupid. If an idea is unscientific, science can't say anything about the validity of the thought, and nothing about whether it's interesting or not. My opinion is that it isn't useless to wonder about the things we can never know. Science might some day fi
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I'm all for eliminating bias in scientific investigations, but we humans just aren't wired up right to pull it off.
That's without even getting into the part where, for a sizable minority (I hope it's a minority) of the species, anything more complex than a wheeled cart might as well work by magic and their lives wouldn't be any different if it did.
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However, it would be odd if photosynthesis could be better described by something other than QM. Anything involving exciting electrons molecules and catalysing reactions using photons is going to be very well described by quantum mechanics.
That's not to say something better won't come along in the future, it's just that currently it's the best theory for that scale of matter.
Re:Quantum Mechanics (Score:4, Informative)
Is it just me or is everything now being explained through Quantum Mechanics?
No it is not just you. Practically everything is explained through QM. The only exception being gravity which we think is governed by QM if only we can find the right model.
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Can't we just credit God or something?
We do, its called the Higg's Boson....haven't you been paying attention? Sheesh...
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Is it just me or is everything now being explained through Quantum Mechanics? Don't understand why people make irrational decisions [slashdot.org]? Quantum Mechanics may be at work. Don't understand how photosynthesis happens? Quantum Mechanics may be at work. Don't understand contradictions in quantum mechanics? Well, that is because sub-atomic paticles may have free will [slashdot.org]? Can't we just credit God or something?
Is it just me or is everything now being explained through "science"?
Don't understand why the Sun rises every morning?
Science may be at work.
Don't understand why water falls from the sky sometimes?
Science may be at work.
Don't understand contradictions in scripture?
Well, that's because the mere human authors may have free will.
Can't we just credit nature with being the way it is or something?
(Sorry, might be snarky but I hope you see the equally valid and often more testable point?)
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It's in EVERYTHING!
Of Course It "Uses Quantum Mechanics" (Score:4, Informative)
Quantum mechanics isn't some tool in nature's toolbox. QM is a way that humans describe all natural phenomena when we explain details of how it all works. QM is a universal framework for describing all the actions of everything that exists.
If scientists are coming up with a new QM description of a physical process like photosynthesis, it's not because they're just discovering that QM is involved. It's because they're figuring out how to describe the process in terms of QM.
In other news, physics turns out to be involved in how the brain works.
Except gravity (Score:3, Interesting)
QM is a universal framework for describing all the actions of everything that exists.
Except for gravity. We can quantize this but only if we put in an artificial energy cut off. Of course most of us physicists believe that there is a proper QM description of gravity to be found but we have not yet do so so we cannot yet say that it is described by QM.
Re:Except gravity (Score:4, Interesting)
Sure, but QM is still a framework for describing everything that exists. That doesn't mean it's a complete framework, even though it's largely complete, and more complete all the time.
Photosynthesis is fully described by QED. That doesn't mean that photosynthesis "uses QM", any more than it "used phlogistons" if it were described analytically in the early 1800s. Or rather, photosynthesis "uses" QM, or phlogistics, or whatever other framework is being used to describe photosynthesis more or less accurately.
The point is that QM is not a process, like "electron cascade", that photosynthesis "uses". It's a framework within which to describe processes like electron cascades that photosynthesis uses.
If we were describing photosynthesis solely in terms of gravitational phenomena, then it might be remarkable to say that our explanation uses QM to describe what happens, because QM doesn't accurately describe gravitation. But that's not what we've got in this case.
Besides, the QM of photosynthesis has been described for quite a while. A new wrinkle in it does not merit a headline announcing that QM is involved.
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Sure, but QM is still a framework for describing everything that exists.
Gravity exists. Gravity is not (yet) explained by QM therefore QM is not a framework that explains everything that exists.
That doesn't mean it's a complete framework...
Completeness is not the issue. Since we cannot quantize gravity successfully yet we have no idea whether it can be done. At the turn of last century you would have been completely wrong had you said that Newtonian mechanics was an incomplete theory but that once complete it would explain the photoelectric effect.
Photosynthesis is fully described by QED.
I completely agree with your point that this was a stupid observation: it
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Just because a framework is for describing everything doesn't mean it will. Just because a framework is incomplete doesn't mean it ever will be complete.
I didn't say that QM explains everything, just that what it is for. Nor did I say that it's ever going to explain gravity.
If a framework that explains all of what QM explains also explains gravity, but contradicts enough of QM's explanations that it's not QM, then we will use the new framework instead when we must explain more than QM can explain.
The point
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QM is a general theoretical framework. Like all science, its principles apply universally. To the extent that QM does not describe some phenomena, people work to improve QM.
Like every other general theoretical framework, it was first produced to explain something specific, but it was found accurate enough to apply to wider and wider scopes. Eventually to a complete scope of everything.
So, regardless of any syntactical argument, I have it right. You have it wrong.
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QM is a way that humans describe all natural phenomena when we explain details of how it all works.
Okay then, explain gravity.
Come on, speak up, there may be a Nobel in it for you.
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The difference is, some things can be adequately described without QM. What they're saying is, photosynthesis can't. I can explain plenty of things in Newtonian physics, some more in General Relativity.
It's kind of like when they discovered how flies fly a few years back. Sure, we knew they could fly, we even knew a great deal about the mechanics involved. But to really figure it out, they had to do some serious testing. What they learned is that flies use 3 different techniques to generate lift, in ev
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Photosynthesis is a process that processes individual electrons. Therefore its workings will require QM to accurately describe, because that scale phenomena behaves in a way that QM most accurately describes. There's quite a lot of quantum biology [wikipedia.org] being reported, now that QM tools and training are both widely available and applicable to biological applications. The larger audience educated in at least the basics of QM (and not just the "it's surreal/magic" of its first several decades) also makes for greate
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I've been reading about Fritz Albert Popp's experiments, for example; how animal biology emits and uses coherent UV light, at the photon level, for cell intercommunication, and how microtubules in the cytoskeletons of cells (including neurons) might act as waveguides.
Interesting stuff. It appears (at this stage anyway) macro-biology and QM work together more than previously imagined.
Well, duh. (Score:5, Funny)
We've been teaching that in physical biochemistry courses for decades. With examples. This is like saying "gravity may be at work in planetary orbits."
Quantum Tunneling (Score:2, Informative)
At Last! proof of the non-existance of God (Score:4, Funny)
Man: "Ah, but look at quantum photosynthesis. That something so incredibly convenient to life (plant and herbivore and omnivore animals) should arise by accident is inconceivable. It proves you exist, so therefore you don't."
God: "Oh dear, I hadn't... <logic>puff</logic>
that reminds me.... (Score:2)
What? No dingos kidneys? (Score:2)
Newsflash.... (Score:4, Interesting)
Science has now discovered that one of the more universal concepts in physics applies to... just about everything above the subatomic scale!
News at 11.
Shouldn't we be terrified now? (Score:2, Funny)
Quantum mechanics has something to do with nuclear bombs, don't it? Shouldn't we be screaming in panic, that our plants might explode like a nuclear bomb at any second? You can't trust those plants, sitting creepy still all the time, plotting our nuclear destruction all the time. We should destroy them all, before they get us!
Oops, forgot to take the blue pill. Take the blue pill now, not the red one.
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i liked it
A step closer to the brain as a quantum computer (Score:2, Insightful)
This research has science a step closer to showing that the brain functions as a quantum computer. Having a quantum computer in our head would explain why we're not like classical computers and have "intelligence", "free will" and "awareness."
Scientists who dismiss quantum processes at work in the body due heat and other quantum noise have little imagination to realize how exquisitely nature works on the molecular level to solve problems like these.
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Eivind, who don't doubt that there's quantum effects going on in the brain, but see no need for them for explaining "intelligence" or "awareness", and know enough psychology to not see any need for "free will" to describe how the mind wor
Re:A step closer to the brain as a quantum compute (Score:5, Insightful)
To be honest, the result here, while important, is entirely unsurprizing. What you're dealing with here is bound electrons, moving from say, a chlorophyll group to a tyrosine amino acid residue. There's nothing knew that electrons, in particular bound electrons (such as in an atom or molecule) can only be accurately described quantum-mechanically. Electrons move through QM 'tunneling' quite a bit, so you simply cannot accurately describe electron-transfer kinetics (which is what's going on here) without QM.
No, it does not. First off, it spells trouble that you seem to view that as a desired end result. Hardly a good way to do science. Second, there is no good reason to believe that the brain cannot be described in terms of straight-up chemistry and biochemistry. We don't know how the brain works, but that doesn't mean it's unexplainable in terms of what we already know. There are plenty of things we haven't fully understood in biochemistry, but that doesn't mean they're generally believed to be unexplainable in the current framework of things. Occam's razor would dictate that that idea should be disregarded until there is some evidence that would make it necessary. No such evidence exists.
Further, your 'philosophical' points are simply invalid. Quantum mechanics says nothing about 'free will', or philosophical determinism for that matter. Quantum mechanics can be interpreted in either way, and has; e.g. the Copenhagen interpretation is nondeterministic, whereas the Bohm interpretation is.
I work with applying quantum mechanics at the molecular level, in biochemical systems, all day long. I have yet to find anyone in my field who thinks there are macroscopic quantum-mechanical processes going on in the human body. That is not due to lack of imagination, it's due to experience with actual quantum mechanics. All chemistry is inherently quantum mechanical. Physics cannot explain an atom even, much less a molecule, with classical theory. The relationship between chemistry and biochemistry is well-understood. The quantum mechanics of chemistry is fairly well understood (due to people doing what I do). And transition in the chemical domain from what is quantum-mechanical to what is classically describable is also well understood. There is simply no physics that explains how or why quantum mechanical effects would disappear and then re-appear orders of magnitude 'upwards' on the scale of matter.
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Quantum mechanics says nothing about 'free will', or philosophical determinism for that matter. Quantum mechanics can be interpreted in either way, and has; e.g. the Copenhagen interpretation is nondeterministic, whereas the Bohm interpretation is.
Maybe stating the obvious...the reason two interpretations are possible, is the system defined by QM is incomplete or underdetermined. What's left is in fact "free", at least in terms of physics theory.
Of course, as you suggest, that may still have nothing to do with "free will", since a person can experience their own will as being "free" or not depending on how they model their own thought process.
Personally I don't think either the Copenhagen or Bohm interpretations are correct. Though of course neithe
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That's a claim I've never seen before. (And I've published and refereed journal articles on free will.) Are we off topic, or does your claim have a quantum angle? Can you provide instructions on how to model my thought processes so as to not experience my will as free? Or does that require some psychological state - say paranoid delusional - which requires more than just a change in modeling a
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Not believing in free will could negatively impact the potential to exercise it.
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Not believing in free will could negatively impact the potential to exercise it.
Yes, definately. Over-believing in it can cause pretty serious problems also. Try flying off a building.
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Are we off topic, or does your claim have a quantum angle?
It doesn't have a quantum angle.
Can you provide instructions on how to model my thought processes so as to not experience my will as free?
Yes, sort of. I wouldn't take it that far though.
Or does that require some psychological state - say paranoid delusional - which requires more than just a change in modeling assumptions to realize?
The 'model' is not entirely arbitrary, and is apparently involuntary to different degrees for different people. Changing your 'modeling assumptions' would be an exercise in voluntarily manipulating your psychological state. And I do think you would qualify as delusional at the point of experiencing yourself as having no free will.
I'm not trying to imply that people have no free will. I'm saying that what I experience as fre
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Drop acid; then try to stop hallucinating. That'll pretty quickly shatter your illusions of free will.
Re:A step closer to the brain as a quantum compute (Score:4, Interesting)
Quantum computers are Turing reducible. It doesn't matter if your computer is classical or quantum, they can still only solve the same kinds of problems. This goes for the brain as well. (For the philosophers, this means that we cannot so easily escape from Searle's Chinese room.)
All of this quantum mind nonsense seems to have stared with Roger Penrose and his ridiculous "theory". (Read: Shadows of the mind and The emperors new mind) He not only claims that the brain is a quantum system (possible, but totally unfounded) but also proposes a formula by which we can calculate how conscious something is! (He bites the ol' ontological bullet really hard, and goes on to claim that even an electron can be conscious, but only a little bit and only once in a great while.)
This article:
http://www.sciencemag.org/cgi/content/summary/287/5454/791?ck=nck [sciencemag.org]
Very clearly outlines the biggest problems for the theory. This is likely where the "Brain is too hot" argument originated. It's a good one, and not likely to go away anytime soon.
More importantly, even if mother nature managed to work around the problem of a hot brain, it still doesn't get us any closer to consciousness. (See my first paragraph above) In the Penrose-Hameroff model, consciousness appears magically during collapse of the wave function. How they came to such a conclusion is beyond reason. That isn't science, it's mysticism.
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Quantum computers are Turing reducible. It doesn't matter if your computer is classical or quantum, they can still only solve the same kinds of problems. This goes for the brain as well.
Doesn't Goedel's Incompleteness Theorem show that the mind is not a Turing machine?
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No, it shows that the mind is inconsistent or incomplete (or both).
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Well, no. As far as I know, Godel never bothered with the subject at all. John Lucas was the first (as far as I'm aware) to use Godel's theorem to argue that the human mind is capable of doing more than any computational system.
Penrose uses a similar argument to achieve the same end. He often get's the credit for it, as he made the idea popular. (I'll skip the description, you can read all about it online.) It's not a terribly good argument, as he presents it, as there are two possible conclusions you ca
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But in different time.
There are problems that quantum computers can solve faster than classical computers (at least in theory
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Nothing science has put forth even attempts to explain why I have a sense of me.
We can observe all we want, and fully map out the behavior of the human brain, and end up proving people are just complex machines. We'd still be left with the question of what our consciousness is.
Should the brain end up being nothing more than a complex machine (and I believe it is), we'll eventually figure it out completely. Once this happens, we'll hit a wall until we can define ourselves (or maybe the rest of you are all
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Nothing science has put forth even attempts to explain why I have a sense of me.
People put way too much importance on that. Your brain is telling you that you have a sense of yourself. Take some of the right drugs and suddenly you can have your brain giving you a sense that you're everyone and everything else too. Doesn't make it true.
It's possible, and in fact likely, that what you perceive as free will and consciousness is an illusion of very complex, but completely deterministic behavior. You haven't offered anything to explain why that wouldn't be the case.
If we manage to figure that one out, the next step would be to explain why anything exists at all.
The question of "why
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It's useful for a creature to be able to model and predict the external world.
And often that requires creating models of other entities.
If those entities also try to model and predict you, you'd have to model them modeling you
Running simulations and predictive models might be better on a computer that can handle infinite states at the same time. Even if it's a bit sloppy and noisy
Maybe "consciousness" is what happens when you hit the limit of recu
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My brain is telling WHO that WHO has a sense of myself?
Illusion? Sure. Like I said, I do believe it's all a complex (deterministic) machine. (We just haven't figured out quantum mechanics fully.)
That doesn't explain why I perceive the illusion, or what I am.
It's a perfectly valid question. If we could get an answer to it, I seriously doubt there would be anything meaningless about it.
Watching Plants does not make them grow faster... (Score:1)
In Fact, it makes them wither and die. We need to stop people from looking at plants or our entire planet is DOOMED DOOMED!!!!!
Other news... (Score:1)
Quantum Mechanics is involved in everything!
(Except maybe gravity. And there's a good chance it's involved in that as well.)
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Yeah, seriously, was gonna post the same thing.
WTF is this shit?
Why this is important (Score:2)
Although, as some commenters have pointed out, everything in the world can be explained in terms of quantum mechanics, until now pretty much everything that is relevant to life on earth didn't seem to need quantum mechanics (QM)... it would work just as well with a chemistry based on a classical physics.
Yeah, we have proven that underneath all that it's really something else by splitting the atom, but aside from the social implications of the atom bomb, nuclear power, and a few more obscure technologies bas
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Although, as some commenters have pointed out, everything in the world can be explained in terms of quantum mechanics,
What about general relativity?
Quantum mechanics is involved in everything (Score:1)
It's just 99.99..9% of the time the result is the same as if classical mechanics were in play.
How many 9's is that? Sorry, guess higher.
The point of the research (Score:5, Informative)
As a quantum physicist, perhaps I can enlighten those of you whose ignorant "of course it's quantum physics! clearly this research is the st00p1d" comments have gained unseemly amounts of modpoints.
Yes, of course quantum mechanics is what is ultimately responsible for everything that happens in the world (at least, as far as we know, though general relativistic phenomena are so far an exception to this). However, despite this fact, it is remarkably the case that the world we perceive on our own macroscopic level does not behave in a quantum way at all, but instead seems to obey classical mechanics. Essentially what it comes down to is that at some point, things start interacting with their environment so much that they start being constantly measured, and so the quantum behaviour disappears. What is not so clear is at exactly what level the world stops being quantum and starts being classical.
In general, the cutoff seems to be somewhere around a molecule. That is although atoms and bonds between atoms are quantum effects, molecules tend be very well modeled using classical forces that were obtained from the quantum models of the bonds.
Because of this, before this research was done, a very reasonable educated guess for one to have made was that the first step of photosynthesis, where an electron essentially is knocked into walking from one part of the molecule to another, would be a classical process, since it happens on the scale of a molecule. Put another way, one might have guessed that when the electron walked from one part of the molecule to another, it did so in a classical (but non-deterministic) fashion by choosing one of the paths available to it and walking down that.
However, what this research has shown is that this is not the case. The electron in fact takes several paths at once. This was detected by performing experiments which showed that there were interference effects; this is the standard approach to take to determine whether something is quantum or classical by the following rough chain of reasoning: you can only see interference patterns when you have cancellations, and you can only see cancellations when something has taken two paths simultaneously but with the opposite phase, so ergo if you see an interference pattern then something quantum must be going on.
This is actually very remarkable because it means that nature specifically engineered a molecule that manifests quantum behaviour on a larger scale then it usually appears. This is a non-trivial thing to have done because, again, the fact that we don't usually see quantum behaviour on this scale implies that it is typically precluded by interactions with the environment, so the fact that this molecule accomplishes this means that it somehow evolved to isolate the electrons involved in photosynthesis from their environment in order to allow them to act in a quantum fashion.
It turns out that the gain from doing this is small, but notable; I didn't read the article, but I did talk to some of the people involved in this research at a couple of meetings and if recall correctly they said that according to their simulations, by doing this nature gained an efficiency of about 10% over what it would be able to get if it were only using classical phenomena. Thus, this effect is actually important for us to understand because it may give us insights into how we can engineer our own devices to use large-scale quantum phenomena to more efficiently harness energy from the sun.
Mod parent up +5 for being sensible not sarcastic. (Score:2)
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Fair questions. To answer your first question... I actually said something less clearly then I should have. When I said "the cutoff seems to be somewhere around a molecule", it sounded like I was saying that the cutoff was for objects that were molecules, but what I should have said was "the cutoff seems to be for phenomena that occur on a scale that is somewhere around the size of a molecule." That is, even though an electron is being involved, and an electron has the size of an infinitesimal point (as
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I seem to recall, from an old scientific american article which I no longer have, that the yeast organisms production of single-isomer alcohol has something to do with quantum effects as well.
Something about one isomer having a slightly more favorable energy state or something... I dunno. Not a quantum physicist. Not any kind of physicist. I like alcohol tho.
No way this can be possible (Score:2)
After all, if most people can't understand quantum physics, how can a fucking squash possibly...
Oh, wait, never mind.
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Most of the time it can be disregarded. Now is an appropriate time for a car analogy and discussion about how quantum effects can be ignored when designing a timing belt.