Comments about the "News in Focus" document in Nature: Long-awaited muon physics experiment nears moment of truth

Following is a discussion about this article in Nature Vol 592 1 April 2021, by Davide Castelvecchi
To study the full text select this link: https://www.nature.com/articles/d41586-021-00833-2 In the last paragraph I explain my own opinion.

Reflection

Introduction

Magnetic Measurements

The discrepancy from theoretical expectations that the original experiment found was tiny, but big enough to cause a stir among theoreticians.
It is very important to know what the theoretical expectations of the experiment were and including the details are. These expectations could be wrong implying there is nothing special involved.
To first approximation, quantum physics predicts that elementary particles such as the muon and the electron have a magnetic moment exactly equal to 2 (in units of measurement that depend on the particle).
It is important that we are discussing predictions based on a certain model. The details of that model should be available.
But a fuller calculation reveals a deviation from this perfect value, caused by the fact that empty space is never truly empty.
The whole problem is that you can never speak about empty space, the same problem you have with a concept like vacuum. No where in the universe there exists a vacuum, nor empty space. Often you can claim that we humans can not measure anything but that means there is nothing.
The calculation performed should model something 'physical'
The space around a muon seethes with all kinds of ‘virtual particles’ — ephemeral versions of actual particles that continuously appear and disappear from the vacuum — which alter the muon’s magnetic field.
All of this is physical speculation.
The more types of particle that exist, the more their virtual versions affect the magnetic moment.
That is correct. You can always claim that there exists something which cannot be directly measured but which increases certain unobservable effects i.e. fields.
The true question is: does this effect also in reality?
To be more specific it is possible that under conditions the magnetic moment varies, but the cause is not related to something virtual ?
This means that a high-precision measurement could reveal indirect evidence for the existence of previously unknown particles.

Tiny discrepancy

The Hunt for new physics

3. Muons speed around a second ring, with a dougnut-shaped magnetic field.

Muons act like tiny magnets spinning on an axis. As they ciculate, their spin axis tilts, or precesses in a way that relate to their magnetic moment.
Okay
Measuring the muon's spin direction, combined with a precises measurement of the ring's magnetic field, reveals the muon's anomalous magnetic moment - the part caused by the interaction with the virtual particles.
This makes only sense if you measure first the ring's magnetic field without any muon's.

Increased accuracy

Reflection 1 - Energy

During Einstein's time the physical state of the universe was not empty but filled with eather, something like a an invissible fog. This concept was cancelled.
Later this was replaced by tiny strings. There after it was demonstrated that there are Higgs particles and a Higgs Field.
Currently the opinion is that the Universe is filled with invissible virtual particles, a type of predecessors of the real particles.
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Created: 30 March 2021

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