A great deal of older science was done by explaining what was already invented. We seem to have reached a point where rarely does a new invention throw off previous science without it being based on new science that was already in disagreement with old science. Part of it is because over the last century we had so many people with the freedom to invent that the easy inventions have already been invented, at least where the inventions don't pose significant moral/legal implications (such as someone inventing a new drug and getting people to try it without going through the proper channels).