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The Candle and the Dark

In 1995, Carl Sagan published The Demon-Haunted World: Science as a Candle in the Dark. The book is, among other things, a sustained argument that science is not a body of facts but a discipline of thought — a way of checking ourselves against a universe that does not care whether we are right.

This archive takes its name from that metaphor. Its aim is modest: to write essays that are careful about evidence, and to push back against claims that borrow the aesthetics of science without its substance.

Method

What to expect

Every essay here tries to do three things: state the claim precisely, show the evidence, and be honest about what the evidence does and does not support.

A few commitments:

  1. Derive, don't assert. Where a result can be shown, it will be shown — even if that means a few lines of algebra.
  2. Cite primary sources. Textbooks and popularizations are useful; they are not the source of truth.
  3. Correct openly. When an essay is wrong, the correction appears in the essay, not quietly in a footnote somewhere else.

A small example

Consider the simplest possible demonstration of why derivations matter. The kinetic energy of a body of mass \(m\) moving at speed \(v\) is

\[ E_k = \frac{1}{2} m v^2. \]

It is easy to state this. It is more instructive to show it falls out of the work–energy theorem:

\[ W = \int_0^v F \, \mathrm{d}x = \int_0^v m \frac{\mathrm{d}v'}{\mathrm{d}t} \, \mathrm{d}x = \int_0^v m v' \, \mathrm{d}v' = \tfrac{1}{2} m v^2. \]

The difference between the two is the difference between being told a fact and being shown why it has to be true. This archive will, wherever possible, prefer the latter.

On pseudoscience

Pseudoscience is not usually obvious nonsense. It is, more often, a real question answered with the wrong tools — or a real observation overinterpreted into a claim the evidence does not support.1 Treating it seriously means taking the trouble to show which step fails, rather than waving the claim away.

What comes next

Upcoming essays are drafted under topics including the statistics of small trials, the physics of common misconceptions, and a careful look at a few recurring pseudoscientific claims. The Tags page will grow as those appear.

If you found a mistake in this piece, a correction is welcome. Open an issue on the GitHub repository or send a note.

  1. Sagan's "baloney detection kit" — a set of rules for evaluating claims — is a good starting point, and will come up repeatedly here. ↩