Tag Archives: physics

The Periodic Table & Astronomy

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Notes from a presentation at Capricon 45, Chicago, Feb. 7, 2024. Any mistakes are mine. The speaker is not responsible for any errors here.

Larry Bartozek will describe the intimate relationship between astronomy and the Periodic Table by looking at how everything we learn about the distant universe comes from dissecting starlight, and starlight comes from excited atoms changing their energy states. Topics will include a brief history of the universe, electron shell structure, spectroscopy on starlight and more! All of this comes from an understanding of the unique “fingerprints” of atoms in the light they give off. Larry will also show the work that he did on the Sloan Digital Sky Survey Telescope.

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Web Site Updates

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I fixed some dead links and made other minor corrections and updates, but did not make any drastic changes in the longer pieces, so their style reflects the times when they were written, years or even decades ago. However, I think they are still relevant to the subjects being discussed.

Chicon 8

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Thursday

On Thursday, Sept. 1, Mia McDavid and I drove to Chicago for Chicon 8: The 80th World Science Fiction Convention at the Hyatt Regency Chicago . This was our 5th Chicon. Previously we had attended:

Despite some glitches, we really enjoyed the Con, and visiting downtown Chicago again.

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College Reunion

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I spent the weekend of June 16-19 at Carleton College. The occasion was my 50 year class reunion, for which I was a member of the gift committee, which in turn was a part of the overall planning committee. Mia (my wife) and I had a room on the third floor of Watson Hall, “3rd Watson” was how we would have referred to it back in the day. I don’t know if the current students refer to campus locations like that. I lived on “6th Watson” my senior year.

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Electrons and Positrons

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I have known about Electron–positron annihilation for at least 52 years, from my course in Atomic and Nuclear Physics at Carleton College in the spring of 1970 if not before. The reaction is

e– + e+ → γ + γ

I had always assumed that the inverse reaction

γ + γ → e– + e+

was also possible because of time reversal symmetry. Apparently so had everyone else, but it has only recently been observed: Matter arises from light? We finally know the answer to this question!. Even now there is a caveat about “virtual” as opposed to “real” photons.

Capricon Notes

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As I wrote previously , Mia (my wife) and I spent last weekend at Capricon, a Chicagoland science fiction convention. We went to most of the Capricons in the ’80’s and ’90’s, but in our first years in Minnesota the pressures of parenthood prevented us from going. Those have eased somewhat and we have been to most of the Capricons (and Windycons) since 2009. While most Capricons have been in the Chicago suburbs, this year the convention was downtown, at the Sheraton Grand Hotel.

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