Brain as CPU

Computer and brain comparison


The human brain is one of the most energy hungry organs in the body.

2400 "food calorie" = 2400 kcal

  • 2400 kcal/24 hr = 100 kcal/hr = 27.8 cal/sec = 116.38 J/s = 116 W

  • 20% x 116 W = 23.3 W

Glucose is the main energy source for the brain. As the size and complexity of the brain increases, energy requirements increase.

The brain makes up 2% of a person's weight. Despite this, even at rest, the brain consumes 20% of the body's energy. The brain consumes energy at 10 times the rate of the rest of the body per gram of tissue.

The average power consumption of a typical adult is 100 Watts and the brain consumes 20% of this, making the power of the brain 20 Watts.


Why Is the Human Brain So Efficient?


The Computer and the Brain, by John von Neumann


the total capacity of human memory is about

4 bits per synapse (4.7 bits - http://elifesciences.org/content/4/e10778)


500 trillion synapses. If each one is carrying 4 bits to be as conservative as possible, that’s a total storage capacity of about 2 quadrillion bits, which is about 0.2 petabytes.

Of course, that’s assuming that our brains store information the same way as a computer—every bit flipped independently, each bit stored forever. Not even close. Human memory is constantly compressing and decompressing data, using a compression scheme that’s lossy

Our core data format for long-term memory appears to be narrative; more or less we store everything not as audio or video (that’s short-term memory, and quite literally so), but as stories.

human brain is almost certainly in some sense holographic storage; damage to a small part of your brain does not produce highly selective memory loss as if you had some bad sectors of your hard drive, but rather an overall degradation of your total memory processing as if you in some sense stored everything everywhere—that is, holographically. How exactly this is accomplished by the brain is still very much an open question;

10 exabytes storage


at least a petabyte, in the same ballpark as the World Wide Web


The human brain, by contrast, integrates processing and memory into the same system. There is no clear distinction between “memory synapses” and “processing synapses”, and no single CPU bottleneck that everything has to go through. There is however something like a “clock cycle” as it turns out; synaptic firings are synchronized across several different “rhythms”, the fastest of which is about 30 Hz.

30 cycles per second

Massively parallel

6 petaflops - 6,000,000,000,000,000 calculations per second

1 exaFLOP - https://aiimpacts.org/brain-performance-in-flops/

1 000 000 000 000 000 000


Neurons are the cells which processes and transmits messages within the brain, and synapses are the bridges between neurons which carry the transmitted messages. Running the numbers – 125 trillion synapses – 4.7 bits/synapse, and about

1 trillion bytes equaling 1 TB (Terabyte).


2.5 petabytes of memory capacity - As a number, a “petabyte” means 1024 terabytes or a million gigabytes, so the average adult human brain has the ability to store the equivalent of 2.5 million gigabytes - three million hours of TV shows.

The human brain has more storage capacity more than 1500 pc. The human brain contains over 100 billion neurons. Simulating 1 second of the human brain activity takes about 82,944 processors. The brain is said to be more complex in connections than a galaxy. The neocorex has the same number of neurons as a galaxy has stars: 100 billion.

With the internet as its nervous system, the world’s connected cell phones and sensors as its sense organs, and data centers as its brain, the ‘whatever’ will hear everything, see everything, and be everywhere at all times.