Your question is quite interesting because it starts out with an openness regarding identity view. Awesome! You ask about what is and are puzzled at the rise of feelings pleasant, painful or neutral. You ask whether we have experimental evidence for such feelings and equations for them. Indeed, you might well be asking for the wave equation for "self" or "consciousness".
An interesting read that delves into the five grasping aggregates is SN22.80 With Khemaka. Khemaka is gravely ill, perhaps dying, and the monks are very worried for him. So they keep pestering him with Dhamma questions in an effort to rouse him and cheer him up.
Reverend Khemaka, the seniors say that these five grasping aggregates have been taught by the Buddha, that is:
the grasping aggregates of form, feeling, perception, choices, and consciousness. Do you regard anything among these five grasping aggregates as self or as belonging to self?’
This Dhamma dialogue is relayed by poor Reverend Dāsaka, who runs back and forth between Khemaka and the senior monks, relaying questions and answers again and again.
Finally, the exasperated Khemaka rouses himself from his almost deathbed and limps over to the senior monks. And what he says is quite remarkable:
For when it comes to the five grasping aggregates I’m not rid of the conceit ‘I am’. But I don’t regard anything as ‘I am this’.
Regarding the nature of physical forces, I think that might be a simple confusion here resulting from the inadequacy of terminology. The attraction of two masses to each other is a nature of space-time, not the ephemeral "I love you, love you not" that the Buddha addresses. The Buddha addresses suffering, the origin of suffering, the cessation of suffering and the path to that cessation. Without physics.
To understand suffering (dukkha), we are given the rather perplexing:
Everything this individual experiences—pleasurable, painful, or neutral—is because of past deeds.
However, for those seeking deeper causes, we have in MN1, that
Delight is the root of suffering
This small phrase (Nandī dukkhassa mūlan’ti) is the E=mc2 of MN1, The Root of All Things. This is the canonical statement of the "I love you, I love you not" dilemma. Yet it goes much deeper, since we are led to explore further into how nandī generates dukkhassa. And THAT is dependent origination (search SE Buddhism).
On a side note, physics is the science of modeling the physical for predictability. Per DN33, there are three ways to see and study the world with:
the eye of the flesh, the eye of clairvoyance, and the eye of wisdom. --DN33
If we say that physics is the second, let us consider that Buddhism is the third. Remember that physics gave us Hiroshima. Buddhism has a different goal. The ending of suffering.