Science only needs to proof one thing: re-incarnation.
With the proof of re-incarnation, then karma can be proven too.
Indeed, if re-incarnation becomes established as a fact through scientific methods, then we have 3 possibilities:
- the next re-incarnated existence is propelled by karma
- by choice
- or through randomness
If it was by choice, then there would be no cockroaches, no worms, no handicapped people neither, so it cannot be "choice".
If it was by randomness, then it would not be scientific, as there is no such thing as a random event, there is always a cause that has a cause that has a cause.
Thus there must be a cause that has a cause that has a cause... and thus the re-incarnation must be the effect of a cause. That is karma, the law of cause and effect applicable to the experiences of living beings.
Yet, so far science has failed to demonstrate re-incarnation. And thus science has not touched on karma neither.
There are many researches made on the subject or re-incarnation and surely there is a reluctance from the scientific world in general as to imply "laws" from reports of people recalling previous lives as there could be numerous other explanations to that than that of re-incarnation.
Now, let's imagine that science gets to prove that the re-incarnation process is true and then gets to prove that karma is true, what would the next challenge be?
The next challenge would be for science to prove that enlightenment is possible.
And I think that would even be harder to touch than proving re-incarnation and karma.
Because if there may not be incompatibility between Dharma and science, there could be between anything samsaric and enlightenment... Or if not incompatibility, at least an enormous resistance!
Thus the scientific journey into Buddhism would follow exactly the order of the 4 Nobel truths...