Scientists under the age of 40 used to make the majority of significant breakthroughs in chemistry, physics and medicine – but that is no longer the case, new research suggests. A study of Nobel Laureates from 1901 to 2008 in these three fields examined the age at which scientists did their prize-winning work. Results showed that before 1905, about two-thirds of winners in all three fields did their prize-winning work before age 40, and about 20 percent did it before age 30. But by 2000, great achievements before age 30 nearly never occurred in any of the three fields. In physics, great achievements by age 40 only occurred in 19 percent of cases by the year 2000, and in chemistry, it nearly never occurred.