Is there any other way to verify the existence of the soul without experiments?

The question was proposed in a discussion, on Facebook, regarding science's resistance to investigating the soul, attributing the matter to mysticism and the supernatural. I highlight below my considerations on the possibility of verifying the existence of the soul:

Tell me: is the atom observable? He will say yes, that's it and a fact: by means of an instrument, it is possible to observe the atom, whose behavior investigation leads scientists to theorize in several hypotheses.

Without the microscope, in the past, man, certainly, I would say that this is madness or supernatural. The point is always to attribute to the supernatural what we do not understand: that is the point.

Are we like that, so knowledgeable about everything, to the point that we can discard the body as an instrument of the soul?

Unfortunately, due to a materialist turn in philosophical paradigms, after the end of the 19th century, many truths were forgotten. Today, when we talk about Psychology, we don't quote Victor Cousin or Paul Janet; when the subject is quantum physics, nobody talks about Mesmer, who, labeled crazy in the past, envisioned theories in agreement with modern physics.

The mistake, always, is to associate Science only with what is observable, forgetting that scientific investigation also advances through the elaboration of theories based on hypotheses based on rational observations. Want to see?

“Dark matter is a hypothetical form of matter that scientists believe exists in the universe due to astronomical observations. It is called “black” because it does not emit, absorb or reflect light or other forms of electromagnetic radiation, making it invisible to our telescopes.

Dark matter is believed to make up about 85% of matter in the universe, but has yet to be directly detected. Scientists infer its existence from the gravitational effects it causes on observed objects, such as galaxies and galaxy clusters.

Although many studies and experiments have been carried out to try to identify dark matter, its nature is still unknown. Several hypotheses have been proposed, including as yet undetected exotic particles, primordial black holes, and alternative theories of gravitation. Dark matter research remains one of the most important and intriguing areas of modern physics and astronomy.”

Would we say that scientists are crazy, chasing something that cannot be observable by our instruments (and may never be) simply because they observed certain effects? Starting from the common census, could we say that dark matter would be something supernatural?

And this is not to enter the scope of theories of parallel universes, which are a logical consequence of some theories of quantum mechanics.

You see: science seeks answers in something unobservable, based merely on effects. Seeks the cause of an effect. And is it really that the effects, in the human scope, are unobservable - or is the tendency to treat any form of spiritualism as mysticism or the supernatural just a prejudice in a field where prejudice should not enter?

Paulo Henrique de Figueiredo says, in “Mesmer: the denied science of animal magnetism”:

The magnetizers very soon proved the relationships of somnambulists with invisible beings. Deleuze, a disciple of Mesmer, in his correspondence maintained with doctor GP Billot for more than four years, from March 1829 to August 1833, was initially reluctant, but finally affirmed: “Magnetism demonstrates the spirituality of the soul and its immortality; it proves the possibility of communication between intelligences separated from matter and those still connected to them.” (BILLOT, 1839)”

[…]

In turn, Deleuze stated: “I see no reason to deny the possibility of the appearance of people who, having left this life, take care of those they loved here and come to manifest themselves to them, to give them healthy advice. I just had an example of this.” (Ibid.)

[…]

“Years later, the magnetizer Louis Alphonse Cahagnet (1809-1885), with courage and determination, spoke to the spirits through his somnambulists in ecstasy, mainly Adèle Maginot, recording in his work more than one hundred and fifty letters signed by witnesses who recognized the identity of the communicating spirits. Cahagnet anticipated this spiritist science research instrument by more than ten years.

We see, therefore, that the soul is as observable as dark matter: through its intelligent effects. The difference is that the Spirit (synonymous with soul) acts of its own will.