Your brain is a quantum computer

This is a theory by Robert Penrose.


Incompleteness

Consider the following statement:

This statement cannot be proved true in this language

If we have a supercomputer that can theoretically answer the question, there are really only 2 outputs:

Paradox

Answer 1 is:
The statement is true

This means the computer could not find a way to prove it in the language.
This however meant the original statement was false, because it was proved true.

This is the one paradox, where it is a self-reference loop.
The answer negates the premise, and the negative premise is then double negated, in an endless loop.

Unprovable

Answer 2 is:
This statement cannot be proved

The statement is true, but it still can’t be proved.
This means the system is either inconsistent or incomplete.

This example is simple enough to create, because natural language is very inconsistent.
You can order words in any way you’d like to make all sorts of illogical jumps.

Gödel

What about mathematics?
It is designed to be perfectly self consistent.

Kurt Gödel was a mathematician who lived in the early 20th century, and is widely regarded as one of the greatest logicians to ever exist.

Gödel’s Incompleteness Theorems
1. In any consistent system that is capable of describing basic arithmetic, there exist statements that are true but cannot be proven within the system.
2. A system cannot prove its own consistency. This implies that certain statements about consistency or the existence of proofs are unprovable within the system itself.

Because some concepts in mathematics are unprovable,
this must mean that mathematics is incomplete.
And since algorithms exist on top of mathematics, they too must be incomplete.

In summary, Gödel’s 2nd theorem states that no system can be self consistent, that is to say you always need an observer from outside of the system to be able to prove it’s consistency.

This means that even a system built purely from self-consistency will still run into incompleteness, unless viewed from outside of itself.

Penrose

Roger Penrose, a Nobel prize winner for his work on relativity within black holes, saw that consciousness was this outside dynamic, he states that our conscious process of knowing does not come from a process limited Gödel’s theorems - that it is not algorithmic.

Consciousness itself can not arise from purely computational processes.
It exists in a system outside of mathematics.

This is called the Penrose-Lucas Argument.

Penrose outlines this argument in 2 books:

  • The Emperor’s New Mind
  • Shadows of the Mind

So if our brains are not classical computers, what are they?

The Quantum Brain

Penrose suggests that the brain operates not on calculable algorithms, but on random quantum mechanics.

The x Measurement Problem of quantum mechanics has a seemingly random element when collapsing the wave function. If an element is truly random then it can not be algorithmic.

Penrose uses the measurement problem to form the following argument:

Any processing performed in a quantum system involving wave function collapse is non-algorithmic, therefore it is not subject to Gödel’s Incompleteness, and therefore conscious reasoning must have a quantum component.

Criticisms

Common critiques:

  • Quantum computation is still believed to be algorithmic
  • Unclear how the injection of randomness frees one from Gödel’s Incompleteness

The Holmsian Fallacy:

  • When you have eliminated all that is impossible, then whatever remains, no matter how improbable, must be the truth.

Basically, all Penrose is saying is that because consciousness can’t be accounted for by things we understand, it must be accounted for by things we don’t, namely the quantum measurement problem.

Meat Computers

Another issue is that quantum behavior is only observable in the most perfect of conditions, like perfectly isolated particle accelerators. Quantum states decay incredibly quickly outside of a perfect vacuum.

This is why quantum computers are so difficult to build.
The inside of the brain is far from this perfect environment needed for quantum processing.

It’s assumed that our meat computers (brains) could only have evolved to make use of relatively macroscopic classical computing processes via electrical impulsing, and thus should be algorithmically consistent.

Hameroff

Stuart Hameroff, an anesthesiologist, discovered that all cells contain structures called microtubules. Each cell can have billions of them and they are used in all sorts of processes.

The interesting thing about them, is they are essentially perfect structures. They have a crystal like structure and form a perfectly repeating pattern in a tube-like form.

More discoveries were made suggesting that microtubules hold a key role in information processing in the brain, namely:

  • They are much more abundant and differently structured in neurons
  • Anesthetics act by disabling microtubules, thereby disabling consciousness.

In the early 1990’s Hameroff started working with Penrose to understand if microtubules may be a candidate for quantum processing within the brain.

Microtubules

The microtubules may create a perfect enough state to be able to store quantum bits (q-bits) of information within their structure - for example in the polar orientation of individual tubulins. These q-bits could maintain quantum states in superposition.

At some point, the quantum state will collapse into a single state, and Penrose believes this is a proto-conscious moment, and our consciousness is the sum result of these collapses happening all of the time.

Orchestrated Objective Reduction

Penrose doesn’t think these collapses are random, but inherently linked to changes in spacetime curvature.

Instead of the x Measurement Problem being a random quantization caused by an observer, it is instead a threshold effect of exact curvatures in spacetime corresponding with exact quantum states. As if specific curves in spacetime will push a quantum superposition over the edge.

This attempts to solve the incompleteness of quantum collapse by describing an objective effect, and the brain uses these quantum collapses to power it’s processing.

This leads to conscious thought, and the ability to transcend classical algorithmic computation.

This theory has been around for 30 years, and most physicists have not taken it seriously. They believe that it is impossible for quantum states to persist for any meaningful amount of time in the messy environment of the brain.

New Evidence

In the last couple of years, there has been new evidence of quantum effects being detected in microtubules in the brain.

The most significant being:
Ultraviolet Superradiance from Mega-Networks of Tryptophan inBiological Architectures

Let’s break it down.

Superradiance

We know that when an atom is hit by a photon (light particle), an electron absorbs the photon and is excited to a specific energy level.
When the electron drops back down it re-emits a photon at that specific energy level, resulting in a specific wavelength of light. This is what gives a material a color, and is called radiance.

Fluorescence occurs when the time this process takes is spread out over time for the different atoms in a material, causing the material to fluoresce, or “glow”.

Superradiance occurs when a group of particles act as though they are entangled, instead of acting as individual atoms. Because we can’t tell which specific atom will absorb the photon, we need to treat the entire group as being in a superpositional state of all possible absorption and re-emitance.

This means that the group acts together, even with one input, and the output is a combined amplification of all entangled atoms. This amplification can only occur when quantum entanglement is present. This is exactly how lasers work, and is very much a quantum effect.

Observation inside the brain

The paper above says that superradiance was observed within microtubules in the brain when hitting it with UV light. Specifically, in the amino acid Tryptophan, one of the components of the tubulin protein which composes microtubules.

In order to observe this superradience, it would require large-scale persistent quantum entanglement of Tryptophan molecules across the microtubule.

The scientists also calculated that in order to see the level of intensity of the superradiance that was observed, the entangled quantum state would need to extend much further and be much larger through the microtubule than was thought possible.

Implications

This suggests that the brain functions not like a classical computer, but like a quantum computer.

It can process vastly more information and possibilities by operating on large networks of entangled q-bits, which exists in a superposition of all possibilities. These q-bit are collapsed by x Orchestrated Objective Reduction which is dependent on the exact state of the present spacetime curvature.

This implies that AGI (Artificial General Intelligence) would need to be based on a quantum computing architecture to have human like consciousness.

Problems

The theorem obviously still has many issues, namely that Penrose conjectures that in order to generate human consciousness, a large fraction of all microtubules that exist in the brain would need to exist in this persistent entangled quantum state.

The probability of this being possible, with our knowledge of how quickly quantum states decay even in the most perfect environments we can create, makes it pretty unbelievable that a network of this scale can exist in the warm, wet and meaty environment of the brain.

However, it is clear that quantum states do exist within the structure of the brain.

Disclaimer

The recent paper makes no claim on what causes consciousness in the brain. It only states that superradiance, a quantum effect, was observed.

The claims of generating consciousness through entangled superpositions stored in microtubules is an argument of Penrose, that these observations appear to support.