Our mind is perhaps the most complicated information processing centers in the universe. Scientist for ages have being trying to understand its working and how it all comes to be. We have come so far and yet we are only scratching the surface, if that. Roger Penrose (Oxford mathematical physicist and Nobel laureate ) claims that our minds works like a Quantum computer on his book The emperor’s new mind. But what exactly does that mean?
To understand this we need to understand two things. One, how is it that our mind works to make us do things. Two, how exactly does a quantum computer work?
How does mind work
The particular question that we try and understand here is, how is that mind can combine a multitude of different information into a single thought.
For example, consider that your are cooking your favorite meal. There are specialized nerve cells collecting information about how the food looks, how it smells, what the temperature is etc. The interesting thing to note is that no where in our brain do these nerve cells meet together i.e., the information remain separate. Yet when a good chef is to add another ingredient to the mix, she makes use of all these information to make decision on when to add the ingredient, how much to add etc.
So how is it that neurons communicate to output a single idea, if its is not connected to one another? This is called the binding problem in neuroscience and to understand this, modern scientist turn to quantum mechanics.
How does a quantum computer work ?
A classical computer makes use of voltages differences , commonly represented as 1’s and 0’s (bits), to store information. These bits can then be manipulated to do a multitude of tasks. Every information that you ever introduce to a classical computer is stored as some combination of 1’s and 0's.
A good representation of the bits are as an arrow, within a sphere as shown in figure 2. In this example, 1’s are when the arrow is pointing upwards and 0’s are when they are pointing downwards. A classical computer can have no other position for the arrow to point, so they have to make use of a large number of such spheres to handle information.
A quantum computer has a “quantum-bit(qbit)” and not a “bit”. A qbit can take any values in between(and including) 1’s and 0’s i.e: the arrow can point in any direction in the sphere (figure 2.b). This means that a lot more information could be communicated with a qbit.
Not just that, a qbit can also displays a peculiar quantum property called entanglement. A group of particles are said to be entangled if a change made to one of them could be somehow reflected in all of them. In terms of the spheres and arrow of figure 2, that would be changing the direction of one of the sphere and all the other (entangled) spheres makes changes to their directions as well. Or in other words information from just one qbit from an entangled qbit system will provide information about all the other qbits.
This is a potential solution to the binding problem. If all the incoming stimuli were entangled to one another, they could “communicate” information and hence be used to provide a single output from collective stimuli.
Penrose and Hameroff claims that microtubules( a kind of protein) found in neurons are the qbits of humans. In this case the direction of the arrows could be represented by the shape of the protein (extended, contracted or anywhere in between).
But not all scientists agree with this. A protein is a massive structure made up of hundreds of thousands of atoms and molecules. And we know that the more the number of atom the soon it looses it quantum properties (another difference of the quantum world).
The debate on the quantum nature of human mind is an open question and is yet to be fully answered. But this is as good a starting point as any.
Footnotes
- This write up is inspired from Dr Jim Al-Kalili’s book Life on the Edge. I would recommend that book to anyone with an interest in biophysics.
- Roger Penrose also makes an argument for how humans could prove Godelian statements and that is what makes us similar to quantum computer.
- The description of quantum computers in this writeup is very rudimentary and limited.
- Roger Penrose deserved a Nobel prize much much earlier.
