Models and the limits of knowledge
Dark Matter Is the Name of a Problem
Galaxies rotate as though they contain far more gravitating matter than we can see. 'Dark matter' names that missing influence — not the substance responsible.
Established ScienceWhat we actually know
Rotation curves of spiral galaxies stay flat far from the centre instead of falling off. Galaxy clusters hold together at velocities that visible mass cannot explain. Gravitational lensing maps mass where there is no light. The cosmic microwave background fits a universe in which most matter is non-luminous. Decades of direct-detection experiments have not identified a particle.
Where the extrapolation begins
The candidate explanations are still open: an undiscovered particle, several of them, primordial black holes, or a modification of gravity itself. Each of those is a different claim about how wrong our map is.
What the novel invents
The novel does not resolve dark matter, and neither does CROWN. It is used as the honest example: a phenomenon we can measure precisely, name confidently, and not explain at all.
Questions to think about
- — What is the difference between naming a phenomenon and explaining it?
- — How would you decide between 'missing matter' and 'wrong theory of gravity'?
Where to read next
- — Rubin and Ford — galaxy rotation curves
- — Planck cosmological parameter results; direct-detection experiment summaries
Continue in the archive