Alpha Centauri A is a G-type star a little over four light years away. Now pick some very particular moment one billion years ago, and zoom in to the precise center of the star. Protons and electrons are colliding with each other all the time. Consider the collision of two electrons nearest to that exact time and that precise point in space. Now let’s ask: was momentum conserved in that collision? ...The bloggist (this is a good post -- I think he rises above "blogger" status) has put his finger on the fulcrum around which all of our public debates about science (abortion, stem cells, environmental degradation, climate change, class action lawsuits based on pollution) turn. At every junction, conservatives demand absolute certainty as to each and every instance with empirical evidence from that instance to back it up. They demand not just a consistent history of "smoking guns," but the very gun used for the crime in question (and usually a few eyewitnesses as well -- preferable themselves).
...The scientific answer to this question is: of course, the momentum was conserved. Conservation of momentum is a principle of science that has been tested to very high accuracy by all sorts of experiments, we have every reason to believe it held true in that particular collision, and absolutely no reason to doubt it; therefore, it’s perfectly reasonable to say that momentum was conserved.
A stickler might argue, well, you shouldn’t be so sure. You didn’t observe that particular event, after all, and more importantly there’s no conceivable way that you could collect data at the present time that would answer the question one way or the other. Science is an empirical endeavor, and should remain silent about things for which no empirical adjudication is possible.
But that’s completely crazy. That’s not how science works. Of course we can say that momentum was conserved. Indeed, if anyone were to take the logic of the previous paragraph seriously, science would be a completely worthless endeavor, because we could never make any statements about the future. Predictions would be impossible, because they haven’t happened yet, so we don’t have any data about them, so science would have to be silent.
If that is the standard -- as it has increasingly been -- then science always loses. This level of absolute determinism can only be found through religious certainty. Ironic, then, that so many who demand specific certainty from science -- which offers libraries of evidence -- adopt that absolute certainty regarding religion, which offers practically none.
Anyway, the article and the comments that follow are engagingly well-written (and by no means taken from the same sheet of music). Recommend.