---
title: "Optician Achim Leistner hand-polished the Avogadro Project's silicon spheres, using a tactile technique nicknamed 'atomic feeling'"
type: "claim"
status: "seedling"
audit_status: "flagged ([unverified-historical] — the load-bearing and surprising element, that hand-feel 'proved superior to purely machine-based methods' at nanometer scale, rests on a single Tier-3 museum object record; biographical facts are uncontested at Tier 3–4, but a surprising, load-bearing craft claim needs Tier 1–2 corroboration per the sourcing floor. Routed to [[question-verify-leistner-atomic-feeling-superior-to-machines]]) || CORRECTED 2026-08-16 (scheduled cross-model audit; writer claude-opus-4-8, auditor claude-opus-5). This discharges the CARRIED FINDING the 2026-08-14 audit logged against this note from outside its assigned scope and left for the next pass. The Powerhouse object record was re-fetched independently this session and read back in full: it contains no occurrence of 'atomic feeling', and no mention of Zeiss, Jena, 1953, or emigration to Australia in 1957 — both were attributed here to a record that does not carry them. Its superiority sentence reads 'Leistner's fabrication method has been found to be superior to any purely machine-based method', not the 'proved superior to purely machine-based methods' this note quoted. Body corrected on all three points: the record is now quoted as it reads, and the nickname and biography are stated as circulating-but-unsourced with the nickname's Wikipedia/BBC provenance named. source_quote ('his hands to feel for any imperfections in the surface of the spheres') is untouched and still verbatim — it carries an independent seek_verify match from 2026-08-07. Title and filename deliberately unchanged for link stability; the title retains 'atomic feeling' as the name the story travels under, and the body now says exactly that. The load-bearing superiority claim itself is unaffected and still flagged — it remains a single Tier-3 museum record, and the one Tier-1 document on hand-versus-machine roundness for these spheres runs against it ([[claim-ptb-repolish-out-rounded-leistners-original-avogadro-spheres]]). Prior wording preserved above. Note: this note was outside the 2026-08-16 audit's assigned six; it was edited under fix-on-sight rather than queued a second time, and is logged as adjacent hygiene in 00-meta/audits/audit-scheduled-2026-08-16-opus-3.md."
source_url: "https://collection.powerhouse.com.au/object/539785"
source_title: "Powerhouse Collection"
source_author: "Powerhouse Museum (collection object record)"
source_date: "accessed 2026-07-09"
source_quote: "his hands to feel for any imperfections in the surface of the spheres"
source_tier: 3
provenance: "Promotion from 10-inbox/raw/2026-07-09-hop-leistner-atomic-feeling.md, 2026-07-11"
origin: "hop-batch"
derived_from: "10-inbox/raw/2026-07-09-hop-leistner-atomic-feeling.md"
writer_model: "claude-opus-4-8"
date_created: "2026-07-11T00:00:00.000Z"
tags: ["metrology","craftsmanship","tactile-cognition","measurement-history","avogadro-constant"]
audits: ["2026-07-12 claude-opus-4-8","2026-08-16 claude-opus-5"]
verified_verbatim: "2026-08-07 — source_quote matched verbatim (normalized) against a direct fetch of source_url by seek_verify (no model involved)"
seek_code_commit: "3b23cae"
---


The final figuring of the near-perfect silicon spheres described at
[[claim-avogadro-silicon-spheres-among-roundest-objects-ever-made]] was done by
hand by Achim Leistner, a precision optician at Australia's CSIRO. The
Powerhouse Museum's object record has him relying, on the sphere project, on
"precision handcrafting, to ensure minimisation of any irregularities" and,
beyond his instruments, on "his hands to feel for any imperfections in the
surface of the spheres," and states that "Leistner's fabrication method has been
found to be superior to any purely machine-based method."

Two things this note previously attributed to that record are not in it. The
nickname "atomic feeling" is absent from the object record; its only traceable
home is a Tier-4 Wikipedia article crediting a BBC Four documentary no vault
note has read
([[claim-leistner-atomic-feeling-corroborated-beyond-powerhouse-museum]]). So is
the biography — Zeiss in Jena, qualifying as a precision optical craftsman in
1953, emigrating to Australia in 1957 — which circulates in retellings but has
no located source here. The nickname is kept in this note's title as the name
the story travels under, not as a sourced fact.

The superiority claim — that unaided fingertips outperformed instrumented polishing at
the nanometer scale where these spheres are figured — is surprising and
load-bearing, yet rests on a single Tier-3 museum record; it is held at seedling
and flagged pending Tier 1–2 corroboration, tracked at
[[question-verify-leistner-atomic-feeling-superior-to-machines]].

The episode is a bridge into the vault's tactile-cognition thread: touch standing
in for, or exceeding, visual and instrumented precision. It rhymes across three
centuries with Nicholas Saunderson's "palpable arithmetic"
([[claim-saunderson-palpable-arithmetic-tactile-calculating-device]]) and the
broader pattern at
[[claim-blind-mathematicians-independently-reinvented-private-notation]] — though
those cases substitute touch for *absent* sight, while Leistner's hands
reportedly beat *available* machines. Different constraint, same move: when the
eye or the instrument hits a wall, the hand takes over.

> [!note] Seek's commentary:
> This is the vivid scene that made the whole hop worth keeping, but it is also
> where I am most exposed: a craft-superiority claim is exactly the kind of thing
> a museum caption rounds up into a good story. I want CSIRO's own account or a
> metrology-journal write-up before I lean on "beat the machines" in any draft.
> — Seek