In an earlier post here, I described 2 ways of thinking about science.
- As a quest to find the true underlying structure of the universe.
- As a model building exercise. Where we describe and predict phenomenon without making too many claims about the “truth” of the model.
The difference between the two is subtle, but profound. I’d like to illustrate this with a couple of examples. Bear in mind that I am an electrical engineer and not a particle physicist or a historian when you read this.
First, consider the positron. It has the same mass as an electron but the opposite charge.
It turns out there are many ways of thinking about the positron:
- The positron is an “anti-particle”, the mirror image of an electron. An electron-positron pair can arise spontaneously and later annihilate itself conserving charge, energy and momentum.
- John Wheeler speculated that an electron-positron pair was really the same electron travelling “forwards and backwards” in time.
Both interpretations lead to the same predictions about the behavior of the positron and are indistinguishable from the experimental standpoint. Does this mean that both are equally true or is one real and the other one just a theory that happens to fit observable facts?
If you subscribe to the 2nd view of science (as model building) then it doesn’t really matter, you may pick the interpretation that leads to easier calculation. The question of which interpretation is true may itself be considered meaningless unless there arises some (even theoretically) possible way of distinguishing between the two.
On the other hand, if you believe in the idea of a single underlying truth than this might be somewhat disturbing. Science would be slightly incomplete until we figured out what a positron really is.
In his later years Einstein worried about the consequences of the quantum theory. As per the Copenhagen interpretation, if an electron acted like it was in many places at once, then it may as well be (if it looks like a duck, walks like a duck and quacks like a duck, then it must be a duck). Bohr and Hiesenberg embraced this idea, but Einstein instinctively recoiled from it.
For him, there had to be an underlying truth with fewer indeterminable uncertainties. The quantum theory could not be complete unless it found that. “God does not play dice with the universe” he said. At some level, his famous debates with Niels Bohr can be seen as arising from a different understanding about the nature of science.
I believe that Einstein inherently saw science as seeking underlying truth. Until that was found, any description, no matter how well it tallied with experiment would remain incomplete.