Under the leadership of Hale， Noyes， and Millikan (and aided by the boomingbooming adj.急速发展的 economy of Southern California)， Caltech grew very significantly in prestige in the 1920s. In 1923， Millikan was awarded the Nobel Prize for physics. In 1925 the school established a department of geology and hired William Bennett Munro， then chairman of the division of History， Government， and Economics at Harvard University， to create a division of humanities and social sciences at Caltech. In 1928 a division of biology was established under the leadershipleadership n.领导能力， 领导阶层 of Thomas Hunt Morgan， the most distinguisheddistinguished adj.卓着的， 着名的， 高贵的 biologist in the United States and a discoverer of the chromosome. In 1926 a graduate school of aeronautics was created which eventually attracted Theodore von Kármán， who later contributed to the creation of the Jet Propulsion Laboratory and who established Caltech as one of the foremost centers for rocket - science. In 1928 construction began on the Palomar Observatory.
Millikan served as “chairman of the executive council” (effectively Caltech，s president) from 1921 to 1945， and his influence was such that the Institute was occasionally referred to as “Millikan，s School.” In the 1950s， 1960s， and 1970s， Caltech was known as the home of arguably the two greatest theoretical particle physicists working at the time： Murray GellMann and Richard Feynman. Both GellMann and Feynman received Nobel Prizes for their work， which was central to the establishment of the socalled “Standard Model” of particle physics. Feynman was also widely known outside the physics community as an exceptionalexceptional adj.例外的， 异常的 teacher and a colorful， unconventional character.
Caltech remains， to this day， a relatively small university， with approximately 900 undergraduates， 1，200 graduate students， and 915 faculty members (including professors， permanent research faculty， and postdoctoral researchers.) It is a private institution， governed by its Board of Trustees.
As of 2005， Caltech claims 30 Nobel laureates to its name. This figure includes 17 alumni， 13 nonalumni professors， and 4 professors who were also alumni (Carl D. Anderson， Linus Pauling， William A. Fowler， and Edward B. Lewis). The number of awards is 31， because Pauling received the prize in both chemistry and peace. Five faculty and alumni have received a Crafoord Prize from the Royal Swedish Academy of Sciences， while 47 have been awarded the U.S. National Medal of Science， and 10 have received the National Medal of Technology. Other distinguished researchers have been affiliatedaffiliated adj.附属的， 有关连的 with Caltech as postdoctoral scholars (e.g.， Barbara McClintock， James D. Watson， and Sheldon Glashow) or visiting professors.
Traditions
There are many annual traditions at Caltech， demonstrating the weird and wonderful creativity of its inhabitants. Every Halloween there is a pumpkin drop from the top of the Millikan Library， the highest point on campus， where the frozen pumpkinpumpkin n.南瓜 supposedly flashes as it hits the ground， when it reaches “the terminal velocity”. And then there is the annual Ditch Day， where seniors ditch school but design elaborate tasks and traps at the doors of their rooms to prevent underclassmen from entering. This has evolved to the point where many seniors spend months designing mechanical/electrical/software obstaclesobstacle n.障碍， 妨害物 in order to confound the underclassmen. The faculty has been drawn into the event as well， and cancel all classes on Ditch Day so that the underclassmen can participate in what has become a highlight of the year.
Another tradition was the playing of the Ride of the Valkyries at 7 AM the morning of finals week with the largest speakers available in the hallway of the freshmen. The playing of that piece is not allowed at any other time， and any offender is dragged off into the showers to be drenched in cold water fully dressed. The playing of the Ride is such a strong tradition that the music was used during Apollo 17 to awaken Astronaut Harrison Schmitt， the only astronautscientist to explore the moon.
Caltech students have been known for the many pranks (also known as RF，s) they have pulled off in the area. The two most famous are the changing of the Hollywood sign to read Caltech， by judiciously covering up certain parts of the letters， and the changing of the Rose Bowl scoreboard to an imaginary game where Caltech soundly trounced MIT. Recently， a group of Caltech students， during the admitted students program at MIT in 2005， pulled a string of pranks， including covering up the word Massachusetts in the “Massachusetts Institute of Technology” engraving on the main building fascade with a bannerbanner n.旗帜， 横幅， 标语 so that it read “That Other Institute of Technology”. A group of MIT hackers retaliated by altering the banner so that the inscriptioninscription n.题字， 碑铭 read “The Only Institute of Technology”.