Showing papers on "Particle horizon published in 1973"

Is the Universe a Vacuum Fluctuation

Abstract: The author proposes a big bang model in which our Universe is a fluctuation of the vacuum, in the sense of quantum field theory. The model predicts a Universe which is homogeneous, isotropic and closed, and consists equally of matter and anti-matter. All these predictions are supported by, or consistent with, present observations.

Standard model of the early universe

Abstract: It would be unjust to brush aside the reservations-ably summarized by Burbidge (1971)-of those who do not whole-heartedly believe in a universe of finite age. Or the reservations of others who do not believe that the initially dense state of the universe was necessarily hot (see Layzer 1968,1972 and references cited). And it is particularly unwise when we recall that the bane of astronomy throughout history has been intolerance of minority views. The models of Friedmann (1922,1924) and Lemaitre (1927) and the discovery of extragalactic recession by Hubble (1929) established securely the concept of an expanding universe. A simple extrapolation of the expansion back in time leads directly to an intial big-bang state of high density. Many cosmologists have been reluctant to accept this conclusion which they condemn as naive. Eddington (1931) in fact viewed it with repugnance. The Eddington-Lemaitre model (Ed­ dington 1930), which has an unstable low-density Einstein model as its initial state, and later the steady-state model of Bondi & G9ld (1948) and Hoyle (1948), appeared therefore more attractive. Both these models nowadays encounter the difficulty of explaining the 3°K background radiation which is widely thought to be a vestigial remnant of a hot big-bang. The idea of a hot and dense early universe is not of recent origin. Prior to the discovery of the 3°K background radiation by Penzias & Wilson (1965), and its identification by Dicke et al (1965), the idea had played an active and a promi­ nent role in the work of Gamow and his colleagues since 1946 (see Alpher, Follin & Herman 1953, Alpher & Herman 1972, Gamow 1953, for reviews). Even earlier attempts to account for the history, distribution, and relative abundance of the elements can be traced back to Suzuki (1931 and previous work cited), Tolman (1922), and Harkins (1917), who realized that in some way an initial state of high density and temperature was necessary. Advocates of cold big-bang theories face nowadays the problem of explaining the 3°K microwave radiation and the cosmic helium abundance; they also have the tactical disadvantage of re­ jecting our only evidence of the big-bang. Rightly or wrongly I shall assume that the 3°K radiation is a vestigial element

Matter and antimatter in the Universe

Abstract: The theoretical situation in regards to the matter-antimatter abundances in the universe is reviewed. The various approaches to the problem are discussed in some detail. (WDM)

Plane-symmetric cosmological model. II

Abstract: For pt. I see abstr. A14186 of 1969. Considering the cylindrically-symmetric metric of Marder a plane-symmetric cosmological model has been derived which is of class higher than one. Various physical and geometrical properties of the model have been discussed. It is found that when the model is filled with disordered radiation it becomes conformal to flat space-time and reduces to a particular case of the Lemaitre universe.