Comments on: Update: Lemaitre vs. Hubble

By: VanceH

VanceH — Tue, 27 Nov 2007 18:50:52 +0000

I know it’s nowhere near the point of this post, but all the references to velocity re-enforces what I think is the most confusing aspect of cosmology for laymen like myself. I still see articles talking about galaxies speeding away from each other, and the red shift ascribed to the Doppler effect. Until I understood that the universe is incredibly homogenous, and the big bang was not an explosion radiating out from a central point most aspects of modern cosmology didn’t make sense (e.g. CMB). I wouldn’t be surprised if this has already been dealt with in cosmic variance, but if not you would do your readers a big favor by decoding what the “effective velocity” really is.

By: Fermi-Walker Transport

Fermi-Walker Transport — Tue, 27 Nov 2007 17:59:33 +0000

Hello All,

Yes, Hubble was sceptical that he had discovered the
“expansion of the universe”. I recall a talk given by Grote Reber
in the late 80’s where he mentioned meeting Hubble in the early 1950’s. He said that Hubble was still sceptical that that the velocity - redshift law implied cosmic expansion.

As an aside, I recall reading that Hubble was not the first to look for a velocity - redshift relationship. Lundmark looked for the relationship around 1915 or 1916, but did not find anything because his sample included both galaxies and some of the globular clusters in our galaxy. Before Shapley came up with his model for our galaxy in 1917, some people thought that globular clusters could be extragalactic.

By: Professor R

Professor R — Tue, 27 Nov 2007 15:54:14 +0000

Hello,
just a note to say there was a nice discussion of Lemaitre’s early version of Hubble’s law in the magazine Astromony Now last year. If I remember correctly, the article shows that Lemaitre did have a crude velocity vs distance graph, cobbled together from data given to him by Slipher….and it was this early graph that gave rise to his idea of an infinitely hot, dense beginning for the U……Cormac

By: Sean

Sean — Mon, 26 Nov 2007 22:55:00 +0000

I’m not sure that Hubble either deduced it or heard it from somewhere else (although either is quite possible). I think that he never insisted that he had discovered “the expansion of the universe,” only that he had found the linear redshift/distance relation. He left those interpretational leaps to the theorists. (And I think it was first de Sitter who predicted the redshift in an expanding universe.)

By: Julianne

Julianne — Mon, 26 Nov 2007 22:25:13 +0000

This actually clears something up for me. As I’ve noted many times while teaching Intro-Astro, it’s straightforward to deduce that universal expansion leads to the Hubble Law, but it is much less obvious to start with the Hubble Law and realize that it implies universal expansion.
Hubble wasn’t that much of a theorist, and I never quite understood how he pulled it off. Having a prediction of the effect before observing it makes much more sense.

By: Fran

Fran — Mon, 26 Nov 2007 18:57:40 +0000

I believe German was the de facto language for science at the time Einstein published most of his works.

By: Nicolas

Nicolas — Mon, 26 Nov 2007 08:21:37 +0000

“Of course, Lemaitre’s paper was in French, so it might as well be in Martian”

It’s a good thing that language wasn’t so much of a drawback for Einstein’s papers though…

By: Ijon Tichy

Ijon Tichy — Mon, 26 Nov 2007 07:38:35 +0000

Well, that does it for me: the Hubble-Lemaitre law.

By: John Farrell

John Farrell — Mon, 26 Nov 2007 02:25:46 +0000

Thanks for posting this. It truly was remarkable how early on Lemaitre started visiting with anyone and everyone he thought might provide him with data pertaining to expansion. He was over in the states on several trips between 1924 and 1927 when he wrote the paper you discuss above.

By: ed hessler

ed hessler — Sun, 25 Nov 2007 19:28:42 +0000

I hope you have started a tradition with something in physics for which you are thankful, even though a year is a long wait!

Other than our apparent intent to screw up life on the planet, what a lovely neighborhood is 3 Sunnyside Place.

Belated but Happy Thanksgiving to you.

By: Lemaitre, Hubble, and translational fidelity! « Entertaining Research

Lemaitre, Hubble, and translational fidelity! « Entertaining Research — Sun, 25 Nov 2007 19:28:31 +0000

[...] You remember Lemaitre of Bible, age of earth and God’s mistakes fame? Over at Cosmic Variance, Sean has a nice discussion as to whether the credit for Hubble’s law …; apparently, Lemaitre got the constant value, now known as Hubble’s constant, quite close; [...]