Archive for May 15, 2019

Eddington at the `Del-Squared V Club’

Posted in History, The Universe and Stuff with tags , , , on May 15, 2019 by telescoper

I’m up to my eyeballs in matters Eddingtonian these days preparing for the big centenary, so I thought I’d share this which I was reminded about this morning. The official results of the 1919 Eclipse Expeditions were announced at a joint meeting of the Royal Society and Royal Astronomical Society on November 6 1919. Members of a certain physics graduate student society at Cambridge, however, were treated to a sneak preview in October of that year, to which the minutes of the 83rd Meeting of the `Del-Squared V Club’ attest:

Arthur Stanley Eddington gave a talk at that meeting, a brief note of which appears on the right-hand page of the minute book shown above. You can see the Newtonian value for the expected deflection of 0.87 seconds at the bottom of the page. There’s also a nice reference to `The Weight of Light’. I had no idea Eddington was a lightweight speaker, but there you are.

I don’t think the Del-Squared V Club exists* any more, so I won’t make the joke that if you want to phone them up you have to go through the operator

*I’m reliably informed that it has been defunct since 1970.

 

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(No) Primordial Non-Gaussianity from Planck

Posted in The Universe and Stuff with tags , , on May 15, 2019 by telescoper

After yesterday’s decennial celebration of the launch of ESA’s Herschel and Planck missions, I noticed that this morning a new paper from the Planck Consortium has arrived on the arXiv. Coincidence?

The other 2018 `last’ papers from Planck were released last year.

Anyway, this is the long-awaited paper IX about primordial non-Gaussianity and the abstract is:

In a nutshell, there’s no evidence for primordial non-Gaussianity from the Planck observations. The paper is rather long, but well worth reading because it shows how much work has to go in to extract higher-order statistical information from CMB data. It’s far harder than the (second-order) power-spectrum, which is no doubt why this paper to so long to emerge.