I just heard a ridiculous claim on what is supposedly a science show "How Do They Do That?" They said that the core of a golf ball is made from a polymer compressed so much that it is equivalent to "40kg of steel fitting in a sphere just 4cm in diameter". That's 1200g/cm3! 1200 times the density of water, 50 times denser than the densest element! I keep reviewing the claim in my head, trying to figure out how I could have misheard it. Even if he said 4kg instead of 40, that's STILL preposterous. Alas, nowhere can I find any claim online that tells me what the correct number is. I see numbers for a whole golf ball, but not for the core (which will be higher.) A whole golf ball is only a little denser than water.