On Reality

This is an interesting little book about reality — obviously, it’s in the title. It’s a staggeringly complex topic, and I was pleased the author could do it such justice in so few words. The chapters make logical sense. The first, on dreams and simulations, takes up the questions: are we dreaming? are we in a simulation? how do we know we’re not just a brain in a vat? The short answer to all of them is: no clue.

The second asks whether the material world is real, and offers five working definitions of what makes something real:

• Reality is what I perceive and experience — reality boiled down to my subjective experience.
• Reality is what a large enough group of people perceives and experiences — which makes room for states, stock markets, cultural norms, and other such spooks.
• Reality is what gives off resistance — a material object becomes real when it meets subjective experience; I know this bed is real because I don’t tumble through it to the floor.
• Reality is what would exist if there were no people — the earth, the moon, a tree falling in a forest, all there whether or not anyone is. Maybe.
• Reality is what is essential — the quanta, or whatever lies beneath them. If that’s what reality is, we might not even have a starting point.

So: is the material world real? It depends which definition you follow, and we really don’t know. Chapter three asks whether the self is real — whether I am real — and we don’t know that either. It threw me for a loop, and I’m still reeling; Descartes’s cogito ergo sum looks sophomoric in light of the material here. I have no idea whether I exist, but the discussions of consciousness are fascinating. Chapter four is the most orthodox, working through Einstein’s special and general relativity: is time real? I’ll have to say I don’t know. Sometimes I find myself questioning the order of things, and this book was a nice reminder that I’m not severely mentally ill — or perhaps I am, but if so I’m in good company. I’m left feeling there should be solid ground to stand on, and instead I’m swimming over the Mariana Trench. If I drown, at least I know I won’t be the only one.

A later thought: there’s a thought experiment in chapter three where a person is asked to observe a quantum phenomenon with a gun pointed at his head. There’s a fifty-fifty chance of the outcome, one tied to survival and one to being shot. If the branching-timelines theory is true — every action spawning new timelines — the observer experiences a hundred-percent chance of survival every time, because by virtue of still existing he hasn’t taken the path where he dies (and he couldn’t experience that death anyway, since it would be instantaneous). But to someone watching, half of all such observers get shot through the head. Bleak. I know the rules of the quantum world differ from the macroscopic — there’s some divide between the IR and UV scales of physics, and a Quanta Magazine article on the incompatibility between general relativity and quantum mechanics that covered this ground, if I recall — but I wondered whether the fact that I’m alive is attributable to it. Maybe I died many times along the way, and those timelines simply branched off. More eerily still: does anyone ever actually experience death? How do we know that in each timeline our own subjective experience doesn’t go on forever? Surely there’s some minuscule probability that allows for it. I don’t quite know how to make the thought clear; someone should have a real conversation with me so we can tease it out.