Comments about the article in Nature: Shedding squeezed light on darkmatter

Following is a discussion about this article in Nature Vol 590 11 Februari 2021, by Igor G. Irastorza

• The text in italics is copied from the article
  
• Immediate followed by some comments
  

In the last paragraph I explain my own opinion.

Reflection

• Reflection 1 - Darkmatter overview.
• Reflection 2 - Heisenberg's Uncertainty principle.
• Reflection 3 -

Introduction

Hypothetical particles called axions could constitute dark-matter - the unseen component of the universe.

Okay

The universe is filled with an invisible unconventional form of matter, whose presence is betrayed by its gravitational attraction to ordinary matter.

This is speculation.

Scientist now have overwelming evidence for the existence of such dark matter at galactic and cosmological scales.

I expect this is a wish. In reality there is no evidence that darkmatter is the solution for the missing matter problem.

However, none of the known fundamental particles has the right properties to compose it.

This is a real problem.

For decades researchers have struggled and failed to find signs of particles beyond the established catalogue.

That is a clear indication that maybe special darkmatter particles are not the solution.

Among the particles suggested by theorists the axion is a favourite for particle hunters.

• See: https://en.wikipedia.org/wiki/Axion
  
• See also: https://www.scientificamerican.com/article/is-dark-matter-made-of-axions/
• See:https://arxiv.org/abs/2012.05029">https://arxiv.org/abs/2012.05029 "Recent progresses in physics of axions or axion-like particles"

They would have been produced in large quantities after the Big Bang and would permeate the Universe and behave exactly like darkmatter.

You can only make this claim if you exactly know how darkmatter behaves and how axions behave, established independent of each other. The central issue is that axions should be subject to the force of gravity, the same way as baryonic particles behave.

If dark matter is made of axions, we would be embedded in a vast sea of these particles.

That could raise a problem for the planets in our solar system, in the same way as (invisible) darkmatter influences the trajectories of stars in our galaxy.

Lowering the experimental noise is an effective way to improve the sensivity of the haloscope to axions.

Okay.

Unfortunately, until now, physics seemed to pose a fundamental barrier to this improvement.

Normally there are technical issues which place limits to certain improvements.

Heisenberg's uncertainty principle of quantum physics states that certain pairs of properties of a quantum system cannot be determined simultaneously with unlimited precision.

No physical property can be measuried or calculated i.e. quantified with unlimited precision. This is specific the case if you want to measure a property which requires two or three measurements. For example the speed or the acceleration of a particle.

Such properties are called complementary variables and include for example position and momentum.

What's in a name. More important is how position and monentum are calculated.

Consequently, quantum noise represents a limit to the acheivable noise level in axion haloscopes.

Squeezed states are specially prepared so that one of the properties in a pair has reduced uncertainty.

More detailed information is required to understand the details of what is unvolved.
Anyway uncertainty is not a physical concept, as such the uncertainty of a particle can not be physical be reduced. Uncertainty is involved which the accuracy, parameters are measured or calculated. IMO the act of measuring always increases to total uncertainty of the process studied.

To respect Heisenberg's principle the complementary variable must than have a larger than normal uncertainty.

Again more detail is required about the physical properties of each pair.

Reflection 1 - Darkmatter overview

The basic constitute of the universe is baryonic matter. Baryonic matter is the cause of gravity. Gravity is the cause that galaxies exists. Galaxies are more or less anatomeous structures in the universe which rotate around a common center. This rotation can be measured and is displayed as what is called a galaxy rotation curve, which shows the speed of the stars as a function of the distance from the center of the galaxy.
A more or less standard curve starts with a speed of zero at its center, increases to a certain value and than becomes flat, or deceases very slowly towards the right end.
This same galaxy rotation curve can also be calculated based on the observed mass and using Newton's Law.
The problem is the calculated curve does not match the observed curve. This means there is more mass in a galaxy than actual what is observed. This missing is called the darkmatter problem, because it is not visible.

Reflection 2 - Heisenberg's Uncertainty principle.

Heisenberg's uncertianty principle says only something about the limits involved, to which extend or accuracy the parameters of certain processes can be measured i.e. calculated. Uncertainty is not a physical concept, that means the uncertainty principle cannot make any claim about the inherent physical state of any parameter of a process, that means insofar the parameter is subject of any change induced by other changes in the process. In reality when any parameter at any moment is measured, such an action can cause other changes in the process, influencing the accuary of possible measurements in the future, increasing uncertainty.

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