The Beginning of the World: Georges Lemaître and the Expanding Universe

At any international gathering these days the dominant theme is likely to be the obvious interdependence of all nations in a global environment that is now perceived to be sharply limited. There is, of course, nothing new in the twin concepts that the world is one and that it is not infinite. For some years prophets, statesmen, scholars, and humble citizens have been blowing on these two horns with increasing vigor. But it took the oil shock of the autumn of 1973 to transform these ideas from the realm of provocative theory to chilling reality. An interdependent, limited world was until quite recently an interesting, slightly worrisome concept, but hardly more immediately threatening than the theory of an ever expanding universe. Suddenly it seems more like the hypnotic eye of a striking cobra, inducing a mixture of terror and immobility.

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Behavior of Irregularities in the Distribution of Matter: Newtonian Approximation

The Large-Scale Structure of the Universe ◽

10.23943/princeton/9780691209838.003.0002 ◽

2020 ◽

pp. 37-137

Author(s):

P. J. E. Peebles

Keyword(s):

General Relativity ◽

Mass Distribution ◽

Newtonian Mechanics ◽

Expanding Universe ◽

Matter Distribution ◽

Newtonian Approximation ◽

Limiting Case ◽

The Universe ◽

Georges Lemaître

This chapter examines the behavior of a given mass distribution in the Newtonian approximation. Discussion of how irregularities in the matter distribution behave in an expanding universe is greatly simplified by the fact that a limiting approximation of general relativity, Newtonian mechanics, applies in a region small compared to the Hubble length. The rest of the universe can affect the region only through a tidal field. Though the point was clearly made by Georges Lemaître, it has not always been recognized that the Newtonian approximation is not a model but a limiting case valid no matter what is happening in the distant parts of the universe. Because of the importance of this result, the chapter discusses it at some length.

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On the Hoyle-Narlikar theory of gravitation

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1965.0146 ◽

1965 ◽

Vol 286 (1406) ◽

pp. 313-319 ◽

Cited By ~ 20

Keyword(s):

Boundary Condition ◽

Action Principle ◽

Einstein Equations ◽

Expanding Universe ◽

Einstein Field Equations ◽

Field Equations ◽

Negative Mass ◽

The World ◽

Theory Of Gravitation ◽

Particle Action

It is shown that the direct-particle action-principle from which Hoyle & Narlikar derive their new theory of gravitation not only yields the Einstein field-equations in the ‘smoothfluid’ approximation, but also implies that the ‘ m ’-field be given by the sum of half the retarded field and half the advanced field calculated from the world-lines of the particles. This is in effect a boundary condition for the Einstein equations, and it appears that it is incompatible with an expanding universe since the advanced field would be infinite. A possible way of overcoming this difficulty would be to allow the existence of negative mass.

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¿De dónde venimos, qué somos, adónde vamos? Un ensayo sobre el sentido de la vida en el universo antrópico

Naturaleza y libertad revista de estudios interdisciplinares ◽

10.24310/nyl.v10i3.3676 ◽

2017 ◽

Vol 10 (1) ◽

Author(s):

Ramón Tamames

Keyword(s):

Meaning Of Life ◽

Big Bang ◽

Human Condition ◽

Expanding Universe ◽

Human Community ◽

The People ◽

The World ◽

Big Crunch ◽

The Big Bang ◽

We The People

Resumen: De dónde venimos. El universo en expansión: ¿del big bang al big crunch? Millones de años de soledad, Paradoja de Fermi y universo antrópico. La fuerza de la evolución y el idioma del ADN. ¿Qué somos? Dueños de la Tierra más Inteligencia Artificial. El sentido de la vida y la condición humana. Pueblo elegido, excepcionalismo, comunidad humana Adónde vamos. Punto omega, azar y necesidad. Ciencia y trascendencia. El principio esperanza y las cuatro preguntas de Kant. La comunidad humana: We, the people of the world. . Where we come from? What we are? Where do we go? An essay on the meaning of life in the anthropic universe. Abstract: Where we come from? The expanding universe: from the big bang to the big crunch? Millions of years of solitude, Paradox of Fermi and anthropic universe. The force of evolution and the language of the DNA. What are we? Landowners + AI. The meaning of life and the human condition. Chosen peo-ple, exceptionalism, human community. Where we go? Omega point, chance and need. Science and transcendence. The main hope and the four questions of Kant. The human community: We, the people of the world. Recibido: 16/10/2017 Aprobado: 5/11/2017

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Homogeneity and Clustering

The Large-Scale Structure of the Universe ◽

10.23943/princeton/9780691209838.003.0001 ◽

2020 ◽

pp. 3-36

Author(s):

P. J. E. Peebles

Keyword(s):

General Relativity ◽

Large Scale ◽

Albert Einstein ◽

Large Scale Structure ◽

Relativity Theory ◽

Expanding Universe ◽

History Of ◽

Edwin Hubble ◽

The Universe ◽

Georges Lemaître

This chapter traces the history of the development of ideas on the large-scale structure of the universe. Modern discussions of the nature of the large-scale matter distribution can be traced back to three central ideas. In 1917, Albert Einstein argued that a closed homogeneous world model fits very well into general relativity theory and the requirements of Mach's principle. In 1926, Edwin Hubble showed that the large-scale distribution of galaxies is close to uniform with no indication of an edge or boundary. In 1927, Georges Lemaître showed that the uniform distribution of galaxies fits very well with the pattern of galaxy redshifts. The chapter then assesses several questions. The first is whether the universe really is homogeneous. Could the homogeneity of the universe have been deduced ahead of time from general principles? Or might it be a useful guide to new principles? It also asks how clustering evolves in an expanding universe, what its origin is, and what this reveals about the nature of the universe.

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From Genesis to Revelation

The Cosmic Mystery Tour ◽

10.1093/oso/9780198831860.003.0010 ◽

2019 ◽

pp. 75-83

Author(s):

Nicholas Mee

Keyword(s):

General Relativity ◽

Spectral Lines ◽

Universe Model ◽

Expanding Universe ◽

Distant Galaxies ◽

Cepheid Variables ◽

Nearby Galaxies ◽

The Universe ◽

Georges Lemaître

The expanding universe model was first championed by the Belgian priest Georges Lemaître, who does not always receive as much credit as he deserves. Lemaître showed how the equations of general relativity predict the universe is expanding, but Einstein was sceptical. Lemaître realized this idea could be tested because spectral lines in light from distant galaxies should be redshifted in an expanding universe and this redshift should be proportional to the distance to the galaxies. Henrietta Leavitt discovered that it is possible to determine the distance to Cepheid variables by measuring the period of their variability. Hubble used this technique to determine the distance to various nearby galaxies and compared this to their redshift data and showed that the universe is indeed expanding.

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