“Not enough atoms in the universe to model your brain”?

“Famously, there aren’t enough atoms in the universe to build a full model of what every cell is doing [in the brain]. It’s a theoretically intractable problem, you can’t even conceive of a computer large enough because there isn’t enough material in the universe to make it.” - Cranach

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Aaron Blumer's picture

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I don't get how there aren't enough atoms to model the human brain if the brain itself is made of atoms.... wouldn't there be enough atoms to model it about 7.5 billion times over, with many atoms to spare?

Views expressed are always my own and not my employer's, my church's, my family's, my neighbors', or my pets'. The house plants have authorized me to speak for them, however, and they always agree with me.

John E.'s picture

Without having looked any further into the Oliver Armitage quote, doesn't this dovetail with philosophy of mind? I mean, if we have a purely mechanistic/atomist understanding of the brain, then, yeah, it's hard to understand how there aren't enough atoms to model the human brain. If, however, like me (and all SI commentators, I'm presuming), one believes that our mind can't be reduced to materialism, then it makes sense.

pvawter's picture

I guess I read that differently. He says there aren't enough atoms in the universe to model "what every cell is doing" in the brain. I assume that's because it would take a very large number of atoms to model what each brain cell is doing. It's not a one to one correspondence.

Bert Perry's picture

What is being addressed here, albeit somewhat clumsily, is the reality that to model how the brain works, you've got to address the interactions between neurons that contact any number of other neurons--and hence a "simple" system of 7.5 billion neurons becomes exponentially more complex. 

A computing analogy: imagine your Intel or AMD microprocessor if the transitors could re-route the metallization to arbitrarily make contact with other portions of the microprocessor--it's enough to make any microprocessor designer either gaze upwards in awe, or get a massive headache.

(side note; AI in systems today is so much simpler than even a gnat's brain, it's not even funny.....the first slide of the presentation is always a neuron, after which the presenter always leaves that concept behind and talks about what he wanted to talk about in the first place)

Aspiring to be a stick in the mud.

Aaron Blumer's picture

EditorAdmin

Some folks at Veith's blog commented on my question there also. It has to do with modeling the processes and interactions and states of neurons. Atoms don't do the same things neurons do, so there aren't enough atoms to model the processes.

It's not a meaningful comparison, though, and leads to people saying things like "there are more neurons in the human brain than atoms in the universe." I'm pretty sure I've heard that claim.

The reason the claim is kind of silly is that we don't need all the atoms in the universe to model the interactions of the brain. There is no relationship between the two. We would do it, if we ever even come close, with algorithms... which don't need any atoms to power them. (Though doing actual calculations would eat up some electricity). So, ironically, even when looking at the physical brain, you would model it in a non-material way.

And yes, as John noted, when you consider the mind, material atoms are even less relevant.

So, I don't think the comparison is useful.

Views expressed are always my own and not my employer's, my church's, my family's, my neighbors', or my pets'. The house plants have authorized me to speak for them, however, and they always agree with me.