## The Expanding Universe – Credit To Hubble Or Lemaitre?

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Perhaps one of the greatest astronomical discoveries of the 20th century may have gone down in the history books as credited to the wrong person. Now known as the Hubble Constant, the theory of an expanding Universe was first speculated by Belgian priest and cosmologist, Father Georges Lemaitre. How did this oversight occur? It may very well be the hand of the man himself who was unpretentious enough to pass on his findings.

According to the the November 10th issue of the journal *Nature*, astrophysicist Mario Livio of the Space Telescope Science Institute is calling for closure about a conspiracy theory of who should be properly credited for the discovery of the expansion theory. For almost a hundred years we’ve been led to believe American astronomer Edwin P. Hubble was the man who explained the universal expansion in 1929 – although he never won a Nobel prize for his work. His findings were based on the achievements of Vesto Slipher, who – through the use of redshift – calculated recessional velocities and paired them with distances to the same galaxies as Hubble’s work. This led Hubble to demonstrate that the further away a galaxy was, the faster it would recede… the Hubble Constant.

However, two years before Hubble published his work, a quiet man called Georges Lemaitre published the same conclusions based on Slipher’s same redshift data and Hubble’s calculated distances.

However, before any accusations can be made, let it be noted that astrophysicist Mario Livio combed through an exhaustive archive of hundreds of letters to the Royal Astronomical Society and the RAS meeting minutes – as well as Father Lemaitre’s Archive. What he found was the good Father had simply omitted the passages himself when he translated the papers to English. In one of two “smoking-gun letters” uncovered by Livio, Lemaitre wrote to the editors: “I did not find advisable to reprint the provisional discussion of radial velocities which is clearly of no actual interest, and also the geometrical note, which could be replaced by a small bibliography of ancient and new papers on the subject.”

What is left for us to ponder is “why” Georges Lemaitre didn’t want to take credit for this discovery. Can there really be an altruistic scientist? One who puts the simple act of discovery above himself?

Livio concludes, “Lemaitre’s letter also provides an interesting insight into the scientific psychology of some of the scientists of the 1920s. Lemaitre was not at all obsessed with establishing priority for his original discovery. Given that Hubble’s results had already been published in 1929, he saw no point in repeating his more tentative earlier findings again in 1931.”

Excuse me, folks… After having read the original news release, I think we should rename the Hubble Telescope to read the “Humble Telescope”.

*Original Story Source: Hubblesite News Release.*

Edwin Hubble, expanding universe, Father Georges Lemaitre, Hubble's Constant

There were a number of people involved. The first metric solution to the Einstein field equation for a cosmology is the Friedman-Lemaitre-Robertson-Walker solution. De Sitter wrote an alternative solution, which turns out to describe inflation and the accelerated cosmology. Lemaitre of these theorists used actual data. This should put him in the same position as Hubble.

As indicated it appears that Lemaitre translated his paper and voluntarily omitted his observation of the relationship between velocity and radial velocity. It seems to be the act of somebody who was diametrically opposite to Hubble, who was a notorious egotist.

LC

Is de Sitter really an alternative solution? I understood it to be a subset of FLRW solutions, where matter-energy isn’t dominating the dynamics but inflation or dark energy is as you imply.

So a good approximation for the Λ-CDM model over most of our universe history, where radiation and matter dominated briefly.

Technically you are right. The de Sitter spacetime was derived from certain Lie symmetries in 5 dimensions, and these Lie symmetries were orthogonal rotation groups with a hyperbolic metric. The FLRW metric also recovers the de Sitter spacetime for a constant energy density in the space. However, this solution is only for a particular patch in the spacetime.

LC

Ah, thanks! The difference between global and local solutions in GR trips me up.

The de Sitter solution is also part of the general formalism which includes the anti-de Sitter spacetime. The Lorentz group is a four dimensional set of algebraic symmetries so(3,1), which generates the group SO(3,1). De Sitter spacetime exists in five dimensions, and is a four dimensional subspace with the symmetries so(4,1). If the additional fifth dimension is a time direction (so there are two directions of time) the symmetries of the spacetime are so(3,2). The anti-de Sitter spacetime is similar to the Poincare ½ plane in that it has hyperbolic dynamics. The boundary of this space on the lower part of the half plane is the real number line, and in higher dimension it is a conformally flat spacetime, which can be a de Sitter spacetime of one dimension smaller. So the de Sitter theory has more general features than FLRW.

LC

The de Sitter solution is also part of the general formalism which includes the anti-de Sitter spacetime. The Lorentz group is a four dimensional set of algebraic symmetries so(3,1), which generates the group SO(3,1). De Sitter spacetime exists in five dimensions, and is a four dimensional subspace with the symmetries so(4,1). If the additional fifth dimension is a time direction (so there are two directions of time) the symmetries of the spacetime are so(3,2). The anti-de Sitter spacetime is similar to the Poincare ½ plane in that it has hyperbolic dynamics. The boundary of this space on the lower part of the half plane is the real number line, and in higher dimension it is a conformally flat spacetime, which can be a de Sitter spacetime of one dimension smaller. So the de Sitter theory has more general features than FLRW.

LC

Ah, thanks! The difference between global and local solutions in GR trips me up.

Technically you are right. The de Sitter spacetime was derived from certain Lie symmetries in 5 dimensions, and these Lie symmetries were orthogonal rotation groups with a hyperbolic metric. The FLRW metric also recovers the de Sitter spacetime for a constant energy density in the space. However, this solution is only for a particular patch in the spacetime.

LC

Is de Sitter really an alternative solution? I understood it to be a subset of FLRW solutions, where matter-energy isn’t dominating the dynamics but inflation or dark energy is as you imply.

So a good approximation for the Λ-CDM model over most of our universe history, where radiation and matter dominated briefly.

A Jesuit high school education has paid off for many a forward thinker. Since tomorrow is Veterans Day, a side note: Lemaitre (and his brother) fought for the Belgians in WWI. Then he earned his doctorate in mathematics, and only afterward became a priest, followed by another doctorate in physics. By the end of his life, he worked on computers.

Lemaitre studied under Harlow Shapley, a new favorite scientist of ours, though he disagreed with Hubble on a few points on which Hubble’s ideas panned out. We wrote a post at Lofty Ambitions blog (loftyambitions.wordpress.com) to commemorate Shapley’s birthday last week.

A Jesuit high school education has paid off for many a forward thinker. Since tomorrow is Veterans Day, a side note: Lemaitre (and his brother) fought for the Belgians in WWI. Then he earned his doctorate in mathematics, and only afterward became a priest, followed by another doctorate in physics. By the end of his life, he worked on computers.

Lemaitre studied under Harlow Shapley, a new favorite scientist of ours, though he disagreed with Hubble on a few points on which Hubble’s ideas panned out. We wrote a post at Lofty Ambitions blog (loftyambitions.wordpress.com) to commemorate Shapley’s birthday last week.

A Jesuit high school education has paid off for many a forward thinker. Since tomorrow is Veterans Day, a side note: Lemaitre (and his brother) fought for the Belgians in WWI. Then he earned his doctorate in mathematics, and only afterward became a priest, followed by another doctorate in physics. By the end of his life, he worked on computers.

Lemaitre studied under Harlow Shapley, a new favorite scientist of ours, though he disagreed with Hubble on a few points on which Hubble’s ideas panned out. We wrote a post at Lofty Ambitions blog (loftyambitions.wordpress.com) to commemorate Shapley’s birthday last week.

Not sure that many people credit Hubble with ‘explaining’ the expansion of the universe, he just pulled the data together (albeit it was kick-ass astronomy and he deserves his place in history for it).

Lemaitre is generally credited as an originator of Big Bang/expanding universe theory, albeit Hoyle gave it its name and Einstein gave it a more sophisticated mathematical framework to operate within.

Hubble deserves credit for lobbying to get astronomy/astrophysics recognised as a legitimate branch of physics – and hence eligible for the Nobel Prize in Physics, an outcome for which subsequent astronomer laureates are no doubt grateful.

Not sure that many people credit Hubble with ‘explaining’ the expansion of the universe, he just pulled the data together (albeit it was kick-ass astronomy and he deserves his place in history for it).

Lemaitre is generally credited as an originator of Big Bang/expanding universe theory, albeit Hoyle gave it its name and Einstein gave it a more sophisticated mathematical framework to operate within.

Hubble deserves credit for lobbying to get astronomy/astrophysics recognised as a legitimate branch of physics – and hence eligible for the Nobel Prize in Physics, an outcome for which subsequent astronomer laureates are no doubt grateful.

We seem to be missing some of the context here. A companion editorial on Nature claims that the context of Livio’s comment is a recent introduced variant of this old controversy of priority.

And one reason Lemaître can have omitted translating his discussions and notes is he was successfully leaving his old geometry for the big bang model. Apparently he tried to fuse Einstein’s static solutions with a later dynamic evolution, something Einstein was not happy with for obvious reasons.

After a detour of suggesting non-isotropic solutions, they closed in on the isotropic expansion. The instability of a static cosmology was made apparent by that time (another Lemaître contribution, perhaps).

So Lemaître could have been quite happy with leaving his old non-starters out of consideration. That Wikipedia link seems to place him in a context of scientific and public success at the time.

After some failed analysis on my own on Newton’s motivations for introducing an absolute room, understandable only in the historical context of his time, I think it is very hard to guess at even the context. And in the end, the actions of individuals aren’t easily amenable for testing.

We seem to be missing some of the context here. A companion editorial on Nature claims that the context of Livio’s comment is a recent introduced variant of this old controversy of priority.

And one reason Lemaître can have omitted translating his discussions and notes is he was successfully leaving his old geometry for the big bang model. Apparently he tried to fuse Einstein’s static solutions with a later dynamic evolution, something Einstein was not happy with for obvious reasons.

After a detour of suggesting non-isotropic solutions, they closed in on the isotropic expansion. The instability of a static cosmology was made apparent by that time (another Lemaître contribution, perhaps).

So Lemaître could have been quite happy with leaving his old non-starters out of consideration. That Wikipedia link seems to place him in a context of scientific and public success at the time.

After some failed analysis on my own on Newton’s motivations for introducing an absolute room, understandable only in the historical context of his time, I think it is very hard to guess at even the context. And in the end, the actions of individuals aren’t easily amenable for testing.

En un artículo de 1957, Robert Merton comentaba que “ningún hallazgo científico recibe el nombre de su descubridor original”. Y eso es lo que ha ocurrido con el descubrimiento del universo en expansión. Sin embargo, el asunto no es tan sencillo como aparece en el artículo del 10 de noviembre.

En 1929, Edwin Hubble estableció la relación entre la distancia y la velocidad de alejamiento de las galaxias y, aunque Georges Lemaître llegó a un resultado parecido dos años antes, no se le puede atribuir a éste último tal hallazgo, pues Lemaître no conocía las distancias a las galaxias en 1927, y tuvo que emplear una aproximación media. Por ello, Lemaître nunca reivindico tal descubrimiento.

Pero, la relación entre la distancia y la velocidad de alejamiento de las galaxias no es lo mismo que decir que el universo está en expansión. De hecho, Hubble tuvo serias dificultades en admitir la expansión del universo y nunca reivindicó tal descubrimiento. fue Lemaître quien quien mostró con datos astronómicos que existe un modelo de universo en expansión, y que ese modelo probablemente refleja el universo real.

La pregunta que debemos formularnos es otra: ¿cuál es la razón por la que Hubble haya pasado a la historia como descubridor de la expansión del universo?

La respuesta la encontramos en la necesidad americana de forjar héroes y en la burda simplificación que hicieron los autores de libros de texto y de divulgación de los años 50, cuando la mayor parte de los astrónomos y cosmólogos que desempeñaron papeles de influencia en el descubrimiento del universo en expansión o en la cosmología de principios de los años 30, ya no vivían.

Eduardo Riaza

Autor de “La historia del comienzo. Georges Lemaître, padre del big bang”, Encuentro 2010.

Sigo el blog: http://georgeslemaitre.blogspot.com/

Running that through google translator, I get that the source is spanish and it says:

“But the relationship between distance and recession velocity of galaxies is not the same as saying that the universe is expanding. In fact, Hubble had serious difficulties in accepting the expanding universe and never claimed such a discovery. Lemaître was he who showed with astronomical data that there is an expanding universe model, and this model probably reflects the real universe.

The question we ask is another: what is the reason that Hubble has passed into history as the discoverer of the expanding universe?”

Because, as the article says, he is credited with the discovery that lead to an explanation, in the form of observation of increased redshift with increased distance (interpreted as Hubble’s law).

Yes, it is based in the desire to forge heroes, cultural domination and simplification in texts. Some of the same can definitely be attributed to your own penmanship (“Author of “The history of the beginning. Georges Lemaître, father of the big bang,””), the title reflects an old and invalidated hypothesis of science as based on efforts of individuals.

But – so what? The market of ideas is as good a method to establish priority as other are, and within science it is primary. What we want to avoid then is, I suggest, fraud and misattribution.