When asked, “How do you know that you exist?”, French philosopher René Descartes replied, “I think therefore I am”, meaning that since he is aware of himself in thought he must exist. But what is the physical process of thinking? Let’s think about this and break our thoughts down to smaller and smaller components and decide if we do indeed exist.
On a chemical scale (atomic and quantum scales to come) our thoughts are simply electric impulses flowing along nerve axons leading to chemical discharges at synapses that trigger more nerves to fire in some coordinated way among brain cells. How this leads to forming a thought, memory, or other sentient functions, scientists still do not know.
Break this down further. At the molecular level, we function because of countless coordinated chemical reactions occurring every second in our body and mind. And within each of these molecules and chemical reactions are the atoms that make up the chemistry of our life. The atoms in turn are mostly made up of vast amounts of space between the nuclei and electrons and to neighbouring atoms. In fact, if you could condense these atoms and remove all the space within them, your entire body would be smaller than a grain of sand. So at the atomic scale we are simply atoms, with a lot of space in and between them, that are somehow held together to form the chemistry of life and our thoughts.
And the atoms in turn are made of smaller stuff yet; quirks and quarks that in turn are made of subatomic particles so small that they move in and out of existence in the weird world of quantum physics. Imagine, there are particles bombarding earth from outer-space that can pass through the entire planet without hitting anything. At this level the earth and everything that makes you and me is so vast and empty that we do not exist. Further down is string theory and brane theory that predicts that we are only experiencing 3 out of a possible 10 dimensions and that we occupy just one of countless multiverses (as opposed to one universe). The scale of all this is infinitesimally small to infinitely big at the same time.
You are made of inanimate matter composed of particles and atoms that are incapable of forming thoughts. Everything that makes you you was here long before you were born. Was your consciousness here before you were born or did it somehow arise as you assembled this lifeless matter to form your life and your thoughts? Is this all you are; your thoughts a chemical/atomic reaction that forms within your skull to be lost upon death; to be released back into the earth and cosmos never to reform? Does your consciousness (your thoughts) go with it? Where are you in all of this? Do you exist?
I think therefore I am – maybe. It depends upon which scale you wish to use and if you believe that inanimate matter can think.
Here is another “thought” from 1975 as I tried to reconcile the science of life and our place in the cosmos.
Time marches on,
The universe is expanding,
Atoms made into matter,
Inanimate matter arranged into life,
Diversity of life abounds,
There must be a guiding hand,