Amateur astronomy Updated 2025-07-16
Astronomer Created 2025-06-17 Updated 2025-07-16
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Age of the universe Updated 2025-07-16
Surely You're Joking, Mr. Feynman chapter An Offer You Must Refuse (a play on words on The Godfather (1972)) has an interesting historical mention from the early 1950s while at Caltech:
The next day, I had the greatest luck in making a decision. God must have set it up to help me decide. I was walking to my office, and a guy came running up to me and said, "Hey, Feynman! Did you hear what happened? Baade found that there are two different populations of stars! All the measurements we had been making of the distances to the galaxies had been based on Cephid variables of one type, but there's another type, so the universe is twice, or three, or even four times as old as we thought!"I knew the problem. In those days, the earth appeared to be older than the universe. The earth was four and a half billion, and the universe was only a couple, or three billion years old. It was a great puzzle. And this discovery resolved all that: The universe was now demonstrably older than was previously thought. And I got this information right away - the guy came running up to me to tell me all this.
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Radio astronomy Created 2025-06-17 Updated 2025-07-16
Radio astronomy is cool because it revealed:The 1974 Nobel Prize in Physics was awarded for pioneering radio astronomy from the late 40s onwards done at the University of Cambridge which was an epicenter of early research in that area, leading to the creation of the Mullard Radio Astronomy Observatory in 1958.
- some very interesting new types of astronomical objects that were not as noticeable in the visible spectrum notably:
- quasars: quasars are extremely redshifted, which means by Hubble's law that they are very far from Earth, so the fact that we could see them at all meant they must have produced immense amounts of light
- pulsars: scientists thought they had found extraterrestrial life when they saw these regularly pulsating signal sources!
- cosmic microwave background which is a major evidence for the Big Bang
- radio wavelengths penetrate Earth's atmosphere better than the visible spectrum making it easier to make ground-based observations
Telescope Updated 2025-07-16
Universe Updated 2025-07-16