There is a strong intuition that coordinated group movement requires coordination — something issuing instructions, or at minimum some shared signal that everybody is responding to.
That intuition is wrong,…
There is a fact almost everybody knows and almost nobody can explain, which makes it a useful place to start.
The Moon presents the same face to Earth continuously. The…
The starting point is a discrepancy. Atomic bonds are extremely strong and the materials made of them are not, by a factor of ten or more - and everything below…
The single fact that organises the subject is that magnetism is produced by moving electric charge, and every electron is both moving and carrying an intrinsic property that behaves like…
The idea that fixes everything else is that suction does not pull. Removing air from a tube lets the surrounding atmospheric pressure push liquid up into it, and the atmosphere…
The single idea that makes all of this make sense is that cold is not a thing being added but heat being taken away and put somewhere else. Everything below…