**1859**– John Tyndall performs careful experiments on light scattering**1869**– Critical opalescence reported for the first time by Thomas Andrews after he observed it in carbon dioxide.**1871**– John Strutt (Lord Rayleigh, Nobel Prize, Physics, 1904) publishes seminal paper on scattering of light by small particles, now commonly known as Rayleigh scattering.**1905**– Albert Einstein (Nobel Prize, Physics, 1921) publishes three papers which forever alter the course of physics. One of them is on random motion of small particles in fluids. This paper contains ideas which are later used to help understand critical phenomena.**1908**– Building off of Einstein’s work, Marian Smoluchowski, a great Polish physicist, attributes the phenomenon of critical opalescence to large fluctuations in density.**1910**– Albert Einstein links the milky-ness at the critical point with scattering, and finds an equation which connects this scattering with density fluctuations, thereby validating Smoluchowski’s hypothesis.**1937**- Lev Landau (Nobel Prize, Physics, 1962) publishes a paper introducing a theoretical framework that is still at the heart of modern understanding of phase transitions. Together with Vitaly Ginzburg (Nobel Prize, Physics, 2003), Landau develops this theory further in 1950 and applies it to superconductors.**1944**- Lars Onsager (Nobel Prize in Chemistry, 1968) obtains exact solution for Ising model in two dimensions at critical point. The importance of this discovery is understood with**universality**- the same results obtained from this simple model apply to a wide variety of other systems in the same "universality class" (scientists always try to use the simplest model possible; in this case, the simplest model gives the exact same results as more complex ones!). Simple is a relative word, however; it was almost another decade before the rest of the scientific community was able to understand Onsager's work, and still more time before the solution was put into context of more "intuitive" approaches.**1960**– Theodore Maiman demonstrates the first working laser at Hughes Research lab. In a few years, lasers will be used to obtain very precise measurements of critical exponents for many different systems, verifying universality experimentally and motivating a flurry of work in the field.**1966**– Leo P. Kadanoff successfully applies the mathematical framework of the renormalization group in the critical point problem.**1971**– Kenneth Wilson solidifies understanding of critical phenomena and universality with renormalization group. He is awarded the Nobel prize for this work in 1982.

Phase transitions and critical phenomena are still major active research topics. And there may be a Nobel Prize for those who achieve an understanding of transitions in high-temperature superconductors....