it's obvious what an observer is. >> reporter: sean carroll is among a group of theoretical physicists who reject the orthodoxy, and refuse to just "get on with their liv they call themselves "everettians," after a lesser known 20th century american physicist who carroll thinks should be a lot better known. his name was hugh everett. >> hugh everett was a graduate student at princeton. and hugh everett, came along saying "well, what if we studied the whole universe as a quantum mechanical system, then we wouldn't have a system a an observer, we only have the system." so everett said we need to iderstand quantum mechani and of itself. and he realized that that implied the existence of many worlds. and, know, everett gotve treate badly. he got ridiculed. he was told he didn't understand quantum mechanics, and we figured this out 20 years ago, the whole bit. so he didn't even apply for a faculty job as a physicist. he left and worked in the defense industry. but we've learned a lot more about how quantum mechanics works since the 1950s. so in fact in my mind everything we've learned has m

guest to introduce sean carroll. brian green is a physicist, a mathematician, professor at columbia university and your other center for theoretical civics. he's also a playwright sometimes an actor in the best-selling author of several science books including the elegant universe in the fabric of the cosmos. he is hosted to emmy award-winning miniseries based on his books. he is also the founder of the world science festival. please welcome dr. brian green. [applause] >> thank you. thank you very much. the quantum cocktail. i was shocked that i did not follow up i sang you get it at the h bar. i will leave now. you've been a great audience, thank you very much. tonight's focus with sean carroll is on quantum mechanics and as i think many of you know in the early years of the 20th century we have a wonderful quite straightforward understanding of the universe are classical physics, right? tell me how things are today and i use the questions of newton or the equations of maxwell or even the equations of einstein to fi

and in our signature segment author and physicist sean carroll on the existence of parallel lives.t on "pbs newshour weekend." >> pbs newshour weekend is made possible by: sbernard and irenartz. sue and edgar wachenheim iii.yl the chnd philip milstein family. the j.p.b. foundation. rosalind p. walter, in memory of george o'neil. barbara hope zuckerberg. decorporate funding is pro by mutual of americade