From The Ghost In My Brain (a book you should read, by the way). I have highlighted the parts that jump out at me in bold.
The human brain is a magnificent device, and the complexity of the human mind it supports is staggering to ponder. It is not possible for us fully to understand the enormity of the changes that take place when someone sustains a traumatic brain injury (TBI) – a concussion – without first having some idea of the phenomenal (astronomical!) computational powers of the device we are considering.
Some supercomputer researchers estimate they’ll need exaflop computing speeds (1,000,000,000,000,000,000 floating-point operations a second) to model a single human brain. Put in layman’s terms. that’s 50 million desktop computers all networked together – and a single such modern desktop is a pretty powerful device. far more sophisticated than the big boxes of the 1960s and ’70s that might each support a company with thousands of employees. Another way to picture this is that 50 million desktop computers laid end- to-end would stretch halfway around the earth, with another three thousand miles to spare
For those of us who are trying to mimic some of the brain’s systems. these are not even the impressive numbers. Rather it is the design of the system – the organization of the software, so to speak, and the impregnated information – that is the truly extraordinary aspect of who we are.
Imagine for a second that you are back standing outside the front door of the plate you lived when you were five years old. What color is the door? Does it have glass in it? Does it open outward or inward? Are there steps in front? A landing? Is there a doorknob or a latch? On which side are the hinges? Remember that door?
Estimates on the size of human memory vary widely. We are not even sure how to define it because, for example, retrieving information from memory also modifies it at the same time. But by almost all reckoning, it is very, very, large.
To get a handle on the numbers let’s imagine that we are writing everything we remember down on sheets of paper, in a 12-point font, on both sides of the paper (one byte per character) The more we have to remember, the more pieces of paper we put on our stack The size of our memory is the height of the stack of paper. So how tall IS the stack?
Harvard researchers have been able to store large amounts of information in DNA molecules and if our brain were made of pure DNA, our memory-capacity stack of paper might stretch out into space for 2485793454 miles – or circle the earth 100 million times, So we know that biological systems can store a great deal of information! Many estimates of actual human memory capacity have the pile of paper extending a much humbler distance – merely up to the moon and back
But now we ask about the real magic – how did you get 238,000 miles up to the moon alongside that stack of paper, halfway back, another six hundred miles, twelve hundred feet, eight inches, fifty-eight pages, and two paragraphs along to find the exact location of the information about that front door you haven‘t seen in twenty years? How did you know to look there? How did you do that in less than a second? Because that is typically how long it takes us to retrieve that long-disused information…
What holds its in the greatest awe is not merely the hardware, but rather the design of the truly elegant system that rims on it. giving us the human mind.
Anti when we start talking about our minds – that which really makes us human – the numbers get even more staggering. At the University of Leicester. James Nelms, Declan Roberts, Suzanne Thomas, and David Starkey calculated that capturing everything that could contribute to a human’s internal state would require 2.6 tredecllllon bits (2.6 followed by 42 Zeros): In their fun paper. they note that to transmit that much information using a Star-Trek-like teleporter. but at high-speed lnternet bit rates. It would lake … several hundred thousand times the current age of the universe.
To simulate concussion damage to a human brain then, we’ll need to gather together those so million desktop computers, the 500,000-mile-high stack or paper, and the almost inconceivable amount of information it takes to construct a human mind, then loose a hurricane on the system, ripping out network lines, laying waste to vast sections of memory, and sending landslides to smash hundreds of hundreds of thousands of computers.
In this way we can imagine the size of the problem we are trying to address: with a single blow w the head – in that moment of impact from concussion – we’ve caused staggering losses in computational power to the unimaginably complex systems that go such a long way in making us human.