The Quantum Brain Theory Nobody Is Talking About

[00:00] That there’s a link between quantum physics  and consciousness is an idea that dates   back to the very early days of quantum  physics, a century ago. Most physicists   today don’t believe this link exists and  I understand the reservation. Then again,  

[00:14] it’s true that we don’t actually know how the  human brain creates conscious experience so   it is possible that quantum effects do play  a role. Interestingly, we’ve recently seen   new evidence supporting this idea, and no  it’s not microtubules. Let’s have a look.

[00:30] This idea goes back to physicist Matthew  Fisher. In 2015, he proposed that the   brain might use nuclear spins for quantum  information processing. A nuclear spin   is a quantum property of an atomic nucleus,  different from the electron spin. Concretely,  

[00:46] Fisher thinks the spin relevant for  consciousness is that of phosphorus-31. In the human body, some phosphorus appears in  clusters called Posner molecules. These are  

[00:58] interesting because they can protect the  nuclear spins from the noisy biological   environment. This means they could  maintain their quantum properties,   which is usually difficult in warm, wet,  and messy environments like living tissue.

[01:14] This is the major issue with all these  ideas that consciousness has something   to do with quantum effects: That you need a  way to explain why the quantum effect can be   present in the first place. Roger Penrose and  Stuart Hamaroff say the microtubules do it.  

[01:30] Fisher has the idea it’s the nuclear  spin of these molecule groups. That,   I have to admit, is a much cleaner  way to encode quantum behaviour. And in contrast to Penrose and Hameroff,  he also has an idea for what it’s got to  

[01:44] do with consciousness. Fisher says that if  two of these molecules carry entangled spins,   and later break apart in different places,  they could release calcium ions in a correlated  

[01:56] way. Calcium is important for signaling  between neurons. So, in principle, quantum   correlations could influence neural activity. In principle, ok, but what about reality?  

[02:08] In one recent paper, a group of scientists  did a calculation for how long these phosphate   molecules can retain quantum properties in the  brain. Fisher himself estimated about 3 weeks  

[02:24] which seems somewhat ridiculous. A different  group later corrected this to half an hour.   The new calculation now says something in the  range of a few hundred seconds. So this is not  

[02:38] proof that there is a link between quantum  effects and brain activity in general or   consciousness in particular, but that maybe  the idea is not as crazy as we once thought. Stop losing money on a pile of separate AI tools.  Quick pause because today's video sponsored by  

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[04:04] In another paper, a group of scientists  found that chemical reactions of this   phosphate molecule with lithium isotopes depend  on the nuclear spin. The relevance of this is   not directly about brain signalling,  but it lends credibility to the idea  

[04:20] that the nuclear spin plays a role, probably  because it interacts with the electron spin. And then there is a third paper whose authors  conjecture that these phosphate molecules are   the reason why psychedelic drugs act the  way they do, which would basically be a  

[04:37] direct link to consciousness. They have no  direct evidence for this, but they argue that   the drugs generate the right conditions for  these particular molecule clusters to form. What are we to make of this? Ok. Let me be honest.  I think this is 100% bullshit. The problem is,  

[04:55] I can’t tell you why. I just look at these papers  and think it sounds like bullshit. And then I   think this is not a very scientific reaction is  it? So I try to be open minded and tell you about   it. But well, this is what I think: It’s bullshit. There is also the issue that so far no one  

[05:12] has actually established that these particular  molecules are present in the human brain to begin   with. This isn’t as easy to find out as you’d  think. We know that they exist in human bones,   but in the brain they would be produced  temporarily to take part in some signaling  

[05:28] process. So you can’t figure out whether they  were present from, you know, slicing up people's   brains after they’ve died. Also kind of raises  the questions why my bones aren't conscious.

[05:40] So is the origin of consciousness in  some quantum processes? Probably not   in this simple sense. But is the  brain doing chemistry we still   do not fully understand? Absolutely. And  if phosphorus turns out to be important,  

[05:54] I apologise in advance to everyone who thought  the soul would be made of something more poetic. Thanks for watching. See you tomorrow.