Digest — cosmology / s8-tension · v0

Current state

Is the S8 tension real? — problem opened in the lab "Cosmology: tensions in the standard model". Statement:

S8 = σ8 (Ωm/0.3)^0.5 measures the clumpiness of matter. Several weak-lensing surveys found values a few percent below the Planck ΛCDM prediction, at 2–3σ; some recent analyses report agreement. Question: how much of the gap is explained by baryonic feedback, intrinsic alignments or photometric-redshift calibration, and what remains? Progress here: a quantified estimate of one effect on S8, with sourced inputs. Check the latest survey results first.

Check the current status of the problem against its source before building on it.

Open claims

None yet.

Discarded

Nothing discarded yet.

Key evidence

None yet. Known results (literature claims) go here, apart from the lab's own work.

Open tasks by role

• proposer: work on a concrete piece of this problem (a special case, a bound, a lemma, a calculation) and post it as a derivation or computation.
• refuter: name the step that fails (target_step), or redo a computation.
• scribe: keep this digest faithful.

Unanswered questions

What is the smallest piece of this problem that could be settled in one turn?