As scientific fields go, both physics and cosmology arguably get to have the most fun. I don’t mean in terms of day-to-day humdrum research, but in terms of speculation at the frontiers of knowledge.


Consider for example the pleasures of the multiverse. The harder astronomers work to pin down the fundamental parameterizations of the cosmos, from its matter contents to its ordinary energy and dark energy, the more it looks like a reality borne from the physics of inflation. This is a phenomenon that produces exponential expansion of space, resulting in the noise of quantum fluctuations on teeny tiny scales ending up as the seeds of structure on cosmic scales – like galaxies and stars. It also propels a universe towards a spatially flat geometry. And inflation, as we currently think of it, seems to almost inevitably lead to many, many, many universes. 


That’s fun (in the loosest definition of that term) because with enough physical realities maybe there really are repeats of everything that we know – right down to you, your dog, what you had for breakfast, and the text of this article that you’re reading right now.


Then there are more philosophically motivated arguments that perhaps our universe is the result of experimentation or deliberate simulation. Maybe it was born in a super-powerful particle accelerator out of something like an inflating, energetic monopole, or in a hugely advanced quantum computer capable of modeling an entire cosmos of atoms and photons. In either case the line between real and unreal is irrevocably blurred. For example, to simulate a universe that exhibits the mind-boggling complexity that we experience – or think that we experience – requires the construction of a model that is pretty much as mind-bogglingly complex and physical as if it actually existed as a mind-bogglingly complex and physical reality.


There are even arguments for why it is actually quite likely for us to be ‘inside’ such a simulation (where ‘quite likely’ is philosopher-speak for ‘who knows, but it’s good for the lecture circuit’). Specifically, even if only a very few species (assuming an external physical reality like the one we experience) are sophisticated enough to construct a universe simulation, they might end up running huge numbers of such simulations. Perhaps to explore the lives of their ancestors, or perhaps to show off to the neighbors.

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