I was in high school when Vincent Magorien wrote what I consider to be the definitive treatise on bulk modulus. That was way back in 1969. But like gravity, bulk modulus is one of those fundamentals that has not and will not change — except maybe in science fiction.
Bulk modulus is a fairly basic concept — the measurement of a fluid's resistance to compression. Hydraulic systems designers usually neglect bulk modulus, or at least consider it negligible. But for high-pressure hydraulic systems (and especially large ones) a fluid's bulk modulus can cause some pretty mysterious things to happen.
What I like best about Vince's article is that it delves into some pretty sophisticated calculations but presents easy-to-understand explanations. So if you have a few minutes and want to gain a greater understanding of bulk modulus, I recommend you read his article, which you can access by clicking here.
Vince has since passed away (May 12, 2006 at the age of 81), but the internet allows us to share his valuable contributions with today's fluid power community, rather than keep them stored away in archives.