[3dem] [ccp4bb] Single Electron Counting, The Measurement Problem, Symmetric Sampling

[Marin van Heel]

*Sorry Tim*...
The problem is *not limited to Cryo-EM* ....  It affects* all forms of
measurements*, including the measurement of *X-ray diffraction patterns*!
What is at stake here is that the* Nyquist-Shannon theorem* is
fundamentally *flawed *(Shannon 1949). In  *X Ray Crystallography* you
unfortunately lose the phases collecting such X Ray diffraction patterns,
but there is one good thing about that, namely: the *low frequency
diffraction peaks* disappear behind the central-beam stop!  The
discrete, *symmetric-sampling
approach* - for the sake of linearity - requires both the *low frequencies*
and the* high spatial frequencies* to be apodized to zero long before
reaching those limits of the sampling space. (After all, the
zero-order frequency of a deterministic *Continuous Fourier Transform*,
covers the whole universe in one direction and that is not a measurable
perspective on the physical world we live in!).

So sorry Tim,  you are not giving a valid argument for *ignoring the
Measurement Problem*!
But it is great to hear from you again, after so many years!

Cheers,
Marin


On Mon, Oct 6, 2025 at 10:46 AM Tim Gruene <tim.gruene at univie.ac.at> wrote:

> I am so happy I do diffraction, not microscopy
> Tim
>
> On Sat, 4 Oct 2025 19:13:10 -0300
> Marin van Heel <000122252ee6fe2c-dmarc-request at JISCMAIL.AC.UK> wrote:
>
> > Dear All,
> >
> > Electron counting cameras in Cryo-EM have an unexpected direct
> > connection to the Measurement Problem in Quantum Mechanics. In fact,
> > the measurement problem already existed in Classical Newtonian
> > Physics due to its Deterministic Mathematical Axioms and is not
> > specifically tied to Quantum Mechanics. The Measurement Problem also
> > existed in Shannon’s sampling theorem. All measurements, and not only
> > those in Electron Microscopy must adhere to symmetric-sampling rules.
> > Check the link to a series of papers:
> >
> >
> https://urldefense.com/v3/__https://www.linkedin.com/feed/update/urn:li:activity:7379515419424022528/__;!!Mih3wA!C29AV9BAnJLQK0X4g1QbhrrdYlIOSdaicdThGgcsDsK9AsNCpOY3O_NRVgkU8_H1Dgs7CEXSsNTCbDBGTpFm5lxBhw$ 
> >
> > Sorry, I know it is tough stuff…
> >
> > Marin
> >
> > ########################################################################
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> --
> --
> Tim Gruene
> Head of the Core Facility Crystal Structure Analysis
> Faculty of Chemistry
> University of Vienna
>
> Phone: +43-1-4277-70202
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