I Don't Think We Realise How Big We Are

Some quick sketching of a way of picturing the consitution of our bodies and brains....

Think of the size of a person compared to an apple. Apples are relatively small, you can hold them in your hand. Something like a fridge is on par with our size. But then there's things like cars and aeroplanes and buildings, which are all larger than us.

And then you can go up in scale to mountains and cities, and oceans. And then again, taking another step outwards there's planets and solar systems. Even our solar system is a speck within a speck (and so on...) in the universe. In our daily lives, and in deep time and space, human beings seem fairly small things.

I think this is part of the reason why many people find it difficult to believe that living things like ourselves, or things with mental lives like ourselves, could be just made out of matter life everything else. When we look at other things on similar size scales to ourselves, there's nothing else that packs in anywhere near as much complexity or sophistication directed towards some purpose. It's difficult to imagine how something as small as a brain could contain our entire mental lives.

But calling our brain 'small' is really just a statement relative to the sorts of scales we are designed and are used to perceiving and considering. Yes, our brain may be so infinitesimal compared to a galaxy, but I don't think we realise just how big, in more meaningful terms, a thing a brain or a body is.

Brains and bodies are made from molecules, and there are vast, vast numbers of molecules involves in any small part of a body of brain, arranged in specific ways in order to bring about the processes of life and cognition. There are trillions1 of cells in the body, and each one of which is a vast complex of "interacting parts". If you view the body from the perspective of an individual cell, it is an incredibly big and complex structure.


UPDATE, 2017: as a thought experiment, consider if the atoms in a typical ant (assume it's 5mm long) were blown up to be 1cm in diameter.  How large would the ant become?  I think the answer to this would help us appreciate just how big and complex even "small" things are.  I posed that question on Quora, and the answer I got was that it'd be approximately 500km long.

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[1]. I belive this is correct, though I am not absolutely sure. In any case, it is an undisputably huge number.