At the turn of the 20th Century, Einstein’s theory of relativity stunned the physics world, but the experimental evidence needed to be found. And so, in 1919, another respected astronomer, Arthur Eddington, observed the deflection of stars by the gravity of the Sun during a solar eclipse. Here’s the story of that famous experiment.

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This episode is sponsored by: Swinburne Astronomy Online, 8th Light

Show Notes

1919 Eclipse and General Relativity by Simon Singh

Illuminating relativity: Experimenting with the stars

How Eddington demonstrated that Einstein was right by Kash Farooq

Not Only Because of Theory: Dyson, Eddington and the Competing Myths of the 1919 Eclipse Expedition by Daniel Kennefick

Space, Time and Gravitation by Sir Arthur Stanley Eddington

Works by Sir Arthur Stanley Eddington available on the Internet Archive

Additional works by Eddington

Transcript

Transcription services provided by: GMR Transcription

Announcer: This episode of Astronomy Cast is brought to you by Swinburne Astronomy Online, the world’s longest running online Astronomy degree program. Visit astronomy.swin.edu.au for more information.

Fraser Cain: Astronomy Cast, Episode 371. The Eddington Eclipse Experiment. Welcome to Astronomy Cast, our weekly facts based journey through the cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain:, I’m the publisher of Universe Today and with me is Dr. Pamela Gay:, a professor at Southern Illinois University, Edwardsville and the Director of Cosmo Quest. Pamela, how are you doing?

Dr. Pamela Gay: I’m doing well, how are you doing Fraser?

Fraser Cain: Doing great. I apologize; I’m a little throaty today. It’s allergy season and I’ve got a bunch of pollen clogged in my throat, I think.

Dr. Pamela Gay: That is sadness.

Fraser Cain: Yes. But I’ll tough through it. Do you have some kind of announcement? Some news? Updates on the Hangout-A-Thon?

Dr. Pamela Gay: I do. So, we are gearing up for the 2015 Cosmo Quest Hangout-A-Thon. It will be April 25th, 26th. We know have the event pages up on Google and I’m for one very grateful that we can now record eight hours at a time. We’re partnered up with the Astronomers Without Borders, Global Astronomy Month, Global Star Party, so we will be bringing you live coverage of star parties around the world, following the night as it passes from nation to nation.

Fraser Cain: How cool is that! It just gets bigger and more insane every year and we watch you go crazier online, 36 straight hours of Pamela broadcasting.

Dr. Pamela Gay: Yeah, if there was an easier way to fund myself, I would, but this is the most reliable. Yeah, I trust you guys to do what’s right more then I trust referees who may not have actually read my grant proposal to do what’s right.

Fraser Cain: Right. Oh yeah, so the event page is already set up, so if you’re listening to this, how could people navigate to the event page to click yes, so that they then get all of the updates and recommendations that will go into your calendar?

Dr. Pamela Gay: So we are +cosmicquest on Google+, that sounds redundant and just look up all of our events, they should be the most recent four posts on our feed, and I will be putting all those links on our Google Hangout Page, that’s over on Cosmo Quest and I have course have forgotten the bitly link and the time it takes me to open up and get to the show.

Fraser Cain: We’ll get that next week. We still have a little time.

Dr. Pamela Gay: We do.

Fraser Cain: All right, well let’s get cracking then.

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Fraser Cain: At the turn of the 20th century, Einstein’s theory of relativity stunned the physics world, but the experimental evidence needed to be found. And so, in 1919 another respected astronomer, Arthur Eddington, observed the deflection of stars by the gravity of the sun during a solar eclipse. Here is the story of that famous experiment.

So we’re continuing our sort of series on experiments and they all seem to be hovering around relativity, which is kind of great, like Einstein was right, as we’ve said in a previous episode, and these are the experiments that showed that he was right. Now this one of course is great because Arthur Eddington looked exactly like David Tennant if I recall.

Dr. Pamela Gay: So, I’m not the only one who found that while preparing for the show. Yeah, there was apparently –

Fraser Cain: Well, you know we did a show. They did a documentary.

Dr. Pamela Gay: The BBC show, yes.

Fraser Cain: Did a dramatization of the Arthur –

Dr. Pamela Gay: Have you seen it?

Fraser Cain: Yes! Yeah.

Dr. Pamela Gay: I love you with hate or hate you with love. I’m not sure which but I tried frantically to find that show because it’s two awesome people, David Tennant, Andy –

Fraser Cain: Serkis?

Dr. Pamela Gay: Yes, Gollum.

Fraser Cain: Yes.

Dr. Pamela Gay: They did a show where they played – David Tennant was Eddington and Andy of Gollum fame was Einstein and it was apparently quite excellent.

Fraser Cain: It was wonderful.

Dr. Pamela Gay: And it was impossible to get in the U.S.

Fraser Cain: Yeah, I guess as a Canadian we get access to the BBC stuff and I remember watching it, like a long time ago, like it must have been six –

Dr. Pamela Gay: Came out in 2008 and HBO ran it in 2010, but I don’t have HBO, so –

Fraser Cain: There’s got to be some place on the Internet, so email Pamela with a link to where she can find it and she will get a chance to watch it as well. But yeah, absolutely terrific, and so it’s great to have it dramatized and so I saw this just wonderful relationship with Eddington and Einstein as they sort of – Eddington went out and helped find the experimental evidence to support these really revolutionary theories. So, what happened in reality?

Dr. Pamela Gay: So, from what I have been able to piece together, the two of them did actually work together on this in so far as Eddington was very much a, “I want to figure things out by the books” kind of man. He did do some stupid things now and then; he did not believe in white dwarfs, it was a belief system, he and Chandrasekhar fought for years and years and years. But at the same time he was also someone that was very interested in trying to figure out things like, why does the sun work? Why do we see what we see? And he was the person who figured out why actually the sun has been glowing for longer then fuels like coal would allow. But one of the other things that just kind of itched at the back of his brain, is this constant annoyance, was our inability to explain the orbit of the planet Mercury.

It was off by just enough, that you couldn’t wipe it away by saying it was observational error, and when Einstein started p