"Dhamma", in its most essential form, simply means "Reality". To follow Dhamma is to follow Reality, and its laws.
That's fine, and I agree. Except for knowing what reality is *exactly*
We have some very good approximations to it, mental maps of it and knowledge of aspects of it.
More than that I'd not be prepared to go.
It's that unavoidable (as far as I can see) gap which means we only have a second-hand (shadows on a cave wall) access to reality.
Some of the laws of reality which the Buddha spoke of as "Dhamma" includes the Law of Cause and Effect (Kamma and its consequences), and the inability to escape from it in samsara (akin to the First Law of Thermodynamics), for example. Wouldn't you agree that those laws are proven and observable?
Cause and effect isn't quite what it used to be so a no, there, although it's a reasonable general rule to consider.
Actions may damp out from simple lack of consequences, for one thing.
(Newton's third law does not apply in the slightest, outside of its proper context.)
Kamma and Karma, no, not in any form strict enough to serve Hindu or Buddhist purposes.
Actions often have consequences, but in no way can the latter be tied neatly to a particular action by timing or proportion.
except on the assumption of some vast and intricate cosmic accounting system.
Even then it would leave some events difficult to understand: 100,000 killed at the same time in the same way in a tsunami, for example. There would seem little individual or carefully balanced about that. It looks and feels far more like something indiscriminate, even random.
That's before moral and ethical implications are managed, or ducked.
Just for one thought, are the suffering to be helped? To whose benefit?
Thermodynamics... The first law is often misquoted and understood, because it is not taken with the second law.
Without the second the first might seem to imply a never-ending cycle of states.
But all the common things used to describe cyclic life by analogy or example are in fact nothing of the kind. Seeds/trees, rivers and rain. etc. all depend on a continuing energy supply which is not renewable, but finite and reducing. The Sun is wearing out.
(Even renewable energy isn't, in the long term: it is either taking from the sun or the spin of the planet.)
The universe will not run out of energy. But by everything we know it will run out of usable energy.
You'd have to get to unending cosmic and spiritual cycles by some other route. Nature and physics tells a different tale entirely. The irreversible heat death of the universe approaches. It's far distant, but it approaches.