Why does this matter?
Physics is all about describing the fundamental nature of the physical world. It requires that we understand fundamental interactions between objects. To do this, we must understand that what physics talks about is about the properties and actions of physical objects.
Physics certainly has a lot of abstractions. However, the abstractions in physics must eventually refer to the properties or actions of physical entities. Or at least help us to understand them in some way.
If an abstraction does neither then it is of no value in physics. Therefore, we must either abandon it. Or modify it so that it is of some use to us.
But in modern physics, we talk about fields as though they do not reduce to the properties or actions of physical entities. Instead, we talk about them as though abstractions cause things.
We should be using these abstractions to describe the actions and properties of entities, which is what these concepts are meant to help us figure out.
For instance, modern physics talks about how gravity is the curvature of space-time.
What the heck is space-time? It is a mathematical abstraction.
How is gravity explained by the curvature of a concept?
Surely gravity is the interaction of physical objects that interact via physical means. Not by curving a concept.
Let us take the concept of fields, such as the electromagnetic field. What is the electromagnetic field? It is a series of mathematical equations which is meant to explain how charged particles interact. It seems to describe vectors in space.
In other words, it is a complicated mathematical description. Of what? Surely of the actions of physical entities?
Physicists have not reduced it to this level, not fully. We do not yet completely understand which actions of physical entities are described by the concept of the “electromagnetic field”.
If we do not try to figure how what actions or properties these abstractions discuss, we are not doing physics. We have failed to grasp a fundamental truth about the physical world.
The Principle of Physical Interactivity reminds us that physical interactions are not caused by abstractions. It tells us that they are caused by physical entities acting on one another. Physics is all about the actions of physical entities. This is what physics is all about discovering.
In conclusion, this is an important principle. It helps us remember how to do physics. It helps us understand the physical world. Not merely the world of abstractions.
Where is the Experimental Evidence For This?
There is none. This is a philosophical axiom of physics which must be accepted in order to do physics properly. What do I mean by saying that it is an axiom of physics?
There are certain fundamental principles of physics which you must accept in order to do physics properly, but which physics itself cannot prove.
For instance, you have to accept that things have identity, that things are what they are. You have to accept that contradictions do not exist in reality. You have to accept the primacy of reality, that is, that things are what they are and that your consciousness observes reality and does not create or shape it.
Additionally, you will have to accept the role of mathematics is a science of method and not the reflection of a Platonic reality of mathematics.
You have to accept that the standard of evidence in physics is experimentation and not random hunches. That you have to go with the evidence of the senses, guided by logic and reason and not random nonsense.
There are a great many of these axioms which it is not the job of physics to prove.
These are philosophical concepts which must be accepted as fundamental principles of physics. But which physics itself cannot prove.
That does not mean that they are not true or that just because you cannot experimentally verify them that they are arbitrary. It means that in order to do physics properly you must accept them as true.
That is why I refer to them as axioms of physics. As far as physics is concerned, these should be accepted as true and outside of the purview of physics to prove.
You might be able to prove some of them using philosophy, but as far as physics goes, they should be viewed as fundamental principles which must be accepted.
There is no infinite appeal to experimentation in physics or any other science.
At some point you will reach a claim which you cannot experimentally prove. But which must be accepted in order for experiments to have any meaning.
What do I mean by this?
Let us suppose that we were to try to experimentally prove the axiom of physics that says physics works by the application of reason.
How would you do this? How would you prove this? Experimentation is a standard of evidence and you cannot validate a standard of evidence by performing an experiment that validates the experimental standard of evidence.
Experimentation cannot by itself prove that experimentation is valid.
Or, suppose you tried to prove the Principle of Physical Interactivity. How would you do that using experimentation? What experiment would establish that physical interacts are physical?
This is a philosophical concept and you need to apply a complex chain of reasoning from philosophical principles to prove that this is true. However, no experiment will show that it is true.
Not everything we know can be validated by experiments. That is not a proper standard of evidence for all claims. And certainly not the philosophical axioms of physics, which physics itself cannot validate.
So, no, there is no experimental evidence for this principle. However, as it is an axiom of physics, one should not expect there to be.
This is why philosophy is so important. Everyone accepts some kind of philosophical principles, axioms are described here. But if you want to do physics properly, you need rational axioms. Such as the Principle of Physical Interactivity.