Just a quick couple of points concerning this very interesting thread:
1) We need to think deeply about what constitutes a cause. Aristotle had a rich understanding of what explains the existence of some entity or phenomenon. Four categories, with a simple example, are: a) material cause -- the brinks, wood etc. of a house; b) formal cause -- the arrangement of the bricks, wood, etc. of a house, not a pile of stuff but a certain design; c) the efficient cause -- the carpenters, mason, electricians, etc.; and d) final cause, the purpose of building the house.
The Age of Reason ironically brought a narrowing of the philosophical understanding of cause, usually a reduction of it to efficient cause -- billiard balls hitting one another, or even worse, as with Hume rejecting causality altogether in favor of causation or a constant conjunction of events. That meant that with the advent of quantum physics a lot of philosophers didn't know how to approach cause and thus many endorsed a radical skepticism.
Thus it is necessary to reexamine what constitutes a cause, that is, what entities, their actions, attributes and the like bring about other entities, their actions, attributes, etc.
2) The best scientists are careful about making philosophical leaps that could undermine the notion of science. Newton, for example, was criticized by some for postulating "occult forces," that is, gravity. How did this invisible, mysterious force hold the earth in its orbit around the sun, pull cannon balls back to the earth, etc? Newton answered, "I make no hypotheses." He simply described what might be called formal causes of the motion of planets, etc, for example, force = mass X acceleration.
Einstein later provided additional causal explanation for moving objects. Space itself is curved by matter and thus we can picture a planet moving in a straight line in curved space, for example, around the rim of the gravity well created by the mass of the sun.
3) It is important for Objectivists not to let our philosophical understandings blind us to scientific discoveries or promising paths of examination. For example, if Bohr and Heisenberg were Objectivists would they have said "No, this stuff can't be right" and not have made the discoveries that they did?
The distinction made on this thread between science and philosophy is a good one. A scientist describes the probabilistic behavior of subatomic particles, the wave-particle duality of light, etc. The philosopher, always consistent with such discoveries, describes the nature of causality and existence. The good philosopher recognizes that just as scientific knowledge is discovered and refined over centuries, so our philosophical understanding of causality and existence can become richer and more refined. And scientists must recognize that if they make unwarranted philosophical leaps, for example, maintaining that quantum physics negates causality, then they are undermining all knowledge, including their own.
(Edited by Ed Hudgins on 4/27, 8:04am)