The cosmic microwave background is relic radiation from the hot early universe, stretched to microwave wavelengths as the universe expanded. Krishna Choudhary and Lester Nare discuss the Princeton researchers thinking about this signal and the Bell Labs observations by Arno Penzias and Robert Wilson. The discovery connected a faint background signal with a major prediction of Big Bang cosmology.
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An expanding universe cools and stretches the radiation traveling through it.
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Princeton researchers and Bell Labs observers approached the background from different directions.
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The microwave background provided evidence for a hot early universe.
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21:35>> Yes. So um the big bang happened, right, according to at least every astronomer, right, up until that point. But the way that people were thinking about the big bang was the same style as Edwin Hubble. Edwin Hubble had figured out the um that the galaxies go away from us, right? And the farther out the galaxy is, the faster it's moving. So that means that the universe is expanding. Well, I just turn back the clock. If the universe is expanding, at some point in the past, it was smaller and smaller and smaller all the way down to the point. So there should have been a point where the universe was exceedingly small and then it blew up into the big bang, >> right? >> Um theoretical astrophysicist Jim
22:16Peebles and Robert Dicki at Princeton University predicted that if that were to have happened, there should be something like a cosmic microwave background, meaning there's leftover radiation from the Big Bang itself. There's a bunch of energy that was released and all of that should take the form of light. It should take the form of light at mill millimeter wavelengths and have a temperature of about 3 Kelvin. They were on their way to creating the necessary radio antenna to measure this when down the street at Bell Labs, Pensas and Wilson were um trying to figure out what was going on.
22:57And that is for the next one because this is a prediction, right? Yes. And this is showing that they could predict that there was a cosmic microwave background. Jim Peebles won the 2019 Nobel Prize in physics because Penszio and Wilson won the real Nobel Prize back in the day for discovering the cosmic microwave background at Bell Labs. Robert Dicki didn't get the Nobel Prize very controversially. And I think after all those years, as a nod to Robert Dicki and his work, Jim Peebles won the Nobel Prize as well. It's interesting the timing difference there for the discovery versus the prediction. Who really deserves it more? The one who predicted or the one who discovered. Yeah. >> Uh but 1964 we have the formulation of
23:37Bell's theorem. >> Yes. Um everyone thinks that John Stewart Bell, the theoretical physicist behind Bell's theorem was always at CERN. But his day job was at CERN. He actually took a year sbatical and he traveled America. He researched at Stanford University and the University of Wisconsin. And during this sbatical he published his most famous paper called Bell's theorem. He derived a mathematical inequality that said there could be an experimental way to disprove Einstein's EPR paradox. Okay, Einstein said that there should be some hidden