✶Explainer02:30
Why humans are the one physical system you need all of science to explain
Every species is exceptional at something, so Deutsch looks for the difference that matters. Imagine aliens with nothing familiar about them trying to explain events on Earth: to explain why a champagne bottle sat in a lab fridge for years, or why one monkey was taken to Sweden and given gold, they would need general relativity, mathematics, the whole of physics and philosophy. No other object requires that. To understand humans well enough, you must understand everything well enough.
- Every animal is exceptional somehow; the question is which exception matters
- Explaining human behaviour requires invoking the content of what humans know
- For quasars and every other object, a sliver of physics is enough
- Humans are the only known physical system whose explanation requires all of science
“in many scientific Laboratories around the world there is a champagne bottle”
“to understand humans sufficiently well you must understand everything sufficiently well”
#human-exceptionalism#explanation#physics#philosophy
✶Explainer06:30
Evolution has no foresight — which is why no animal ever built a campfire
There are only two known knowledge creators: biological evolution and human thought. Evolution is limited in range because it cannot see a problem and conjecture a solution, so it can only reach things approachable by successive viable steps. Bombardier beetles got to boiling water because lukewarm water was already useful. Nothing got to campfires, because there is no partially functional campfire. Explanatory creativity jumps the non-viable gaps.
- Evolution's knowledge creation happens before natural selection, which was Darwin's insight
- Evolution can only reach solutions via chains of individually viable organisms
- Bombardier beetles reached boiling water through useful intermediate steps
- No species in billions ever made a campfire — there is no half-campfire
- Human creativity can build toward an idea whose intermediate stages are useless
“biological evolution is inherently Limited in its range and that is because biological evolution has no foresight it can't see a problem and conjecture a…”
“out of all the billions and billions of species that have ever existed none of them has ever made a campfire”
#evolution#creativity#knowledge-creation#darwin
✶Explainer36:30
Humans are universal computers — but not universal quantum computers
Naval assumes humans are universal quantum computers and Deutsch corrects him. Everything obeys quantum physics, so in a trivial sense everything is a quantum computer, but that is not a useful use of the term. A quantum computer is a machine whose computation relies on distinctively quantum effects, mainly interference and entanglement. Deutsch does not think the brain works that way, though he grants that nobody knows exactly how it works.
- The label is partly terminological — everything is quantum, so the word must earn its keep
- Quantum computers exploit interference and entanglement specifically
- Telling quantum-computing companies they have already succeeded would not go down well
- Deutsch finds a quantum brain very implausible but does not claim certainty
“everything is quantum so everything is a quantum computer but that's not a useful way of using the term”
“we don't know exactly how it works and some people do think it may rely on Quantum effects in which case it is a quantum…”
#quantum-computing#brain#computation#physics
✶Explainer39:30
Non-locality is smuggled in with wave function collapse
Deutsch's layman's account: only versions of quantum theory that include wave function collapse look non-local. In those versions the equations of motion stop applying at an undefined moment called observation, and something completely different takes over — and that something is the non-local part. The thing they call non-local is the same thing they refuse to explain. Express quantum theory so its equations hold everywhere, as Everett did in 1955, and it is local.
- Non-locality only appears in collapse versions of quantum theory
- Observation is undefined in those versions, and the equations simply stop applying there
- The non-local step is exactly the step they decline to explain
- Collapse is also where minds affecting matter and thinking electrons get in
- Everett's formulation keeps the equations everywhere, and the equations are local
“the thing that they say is non-local is also the thing that they refuse to explain”
“Everett found this way of expressing quantum theory in 1955”
#non-locality#quantum-physics#wave-function#everett
✶Explainer42:00
The wave function is not a field in this room
People almost always hand-wave the wave function into a field on space and time, like temperature or the electric field varying point to point. That is wrong. Two electrons do not have two fields in the same space; they have one wave function in a higher-dimensional space — one electron takes three dimensions plus time, two take six plus time. The particle-versus-wave framing survives only because everyone pictures the simplest case.
- Treating the wave function like temperature or an electric field is the standard mistake
- Two electrons share a single wave function in six dimensions plus time
- Two photons approaching the slits are easy to picture; two waves need a much larger space
- Conventional interpretations resort to hand-waving as soon as you go past one particle
“the wave function of two electrons is a single function in a higher dimensional space”
“this is a way in which the conventional interpretations just instantly resorts to hand waving as soon as anything other than the simplest case is…”
#wave-function#quantum-physics#double-slit#dimensions