⚖ The five hurdles
Five things any idea about time has to get past. They're a checklist, not a verdict — and the scores are made to be argued with.
1 · Matches relativity tests
Special and general relativity have passed every test for over a century — particle accelerators, atomic clocks, GPS, gravitational waves, black-hole images. An idea about time that contradicts them has to explain all that evidence away. Tired light struggled here (see it).
2 · Present predicts future
In our world, knowing the present fixes the future — that's what lets physics forecast anything. Some ideas break this: universes with time loops (Gödel) and two time dimensions (Craig & Weinstein).
3 · Allows stable matter
Atoms, planets and people need stable matter. Extra space dimensions destabilise orbits and atoms; extra time dimensions let particles decay into heavier ones (Dorling). Several multi-time proposals haven't yet shown how they avoid this.
4 · Explains the arrow
A full account of time should say why it runs one way. Most theories of the fundamental laws don't try — even relativity (Spacetime) treats past and future alike and inherits the arrow from the early universe. Few ideas pass this hurdle.
5 · Makes a new testable prediction
An idea that predicts nothing new can't be checked, however elegant. Some famous proposals score poorly here (the zero-energy universe, thermal time); some speculative ones do well because they stuck their necks out (Smolin's black-hole universes).
Argue with the scores
The scores are a first-pass judgement drafted with Claude, an AI. Every partial or failing score has a written reason — open any idea, and use Score it yourself where you disagree.
See it in the labs
Sources: Test bench method (D-012, D-027); reasons per idea in src/data3.js.