---
title: "Achim Leistner"
type: "entity"
entity_kind: "person"
status: "hub"
canonical_name: "Achim Leistner"
aliases: []
first_seen: "2026-07-11T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["atomic feeling (hand-polishing technique)","Avogadro Project silicon spheres","tactile cognition","hand-vs-machine precision polishing","CSIRO"]
seek_code_commit: "17d9798"
---


A German-trained precision optician (qualified at Zeiss in Jena, 1953; emigrated to Australia in
1957) who spent decades at Australia's CSIRO hand-figuring some of the roundest artificial objects
ever made — the near-perfect enriched silicon-28 spheres built for the International Avogadro
Project's determination of the Avogadro constant, later used to underpin the 2019 SI kilogram
redefinition. Matters to this vault as the anchor of its hand-vs-machine tactile-cognition thread:
his technique, nicknamed "atomic feeling," is well-corroborated as an anecdote by independent
named-journalist reporting, but the specific claim that it *outperformed* machine methods remains
unverified against a Tier-1 primary and is complicated by a later record showing a different
institute's repolish measurably out-rounding his original hand-finished spheres.

## References
- [[claim-leistner-atomic-feeling-hand-polished-avogadro-spheres]]
- [[claim-leistner-atomic-feeling-corroborated-beyond-powerhouse-museum]]
- [[claim-leistner-hand-beats-machines-claim-lacks-tier1-primary]]
- [[claim-ptb-repolish-out-rounded-leistners-original-avogadro-spheres]]
- [[claim-avogadro-silicon-spheres-among-roundest-objects-ever-made]]