This chapter explores how the very evident departures from Albert Einstein's homogeneity—stars in galaxies in groups and clusters of galaxies—might have formed in an expanding universe. In the established cosmology, cosmic structure formed by the gravitational instability of the relativistic expanding universe. The early confusion about the physical meaning of this instability is an important part of the history. The chapter reviews these considerations, along with assessments of early scenarios of how cosmic structure might have formed. A theory of how the galaxies formed in the big bang cosmology has to provide a physically consistent picture of how cosmic structure evolved from the very different conditions in the early stages of expansion. That consideration is absent in the 1948 steady-state cosmology, so thinking about structure formation had to be different.
{"title":"How Cosmic Structure Grew","authors":"P. Peebles","doi":"10.2307/j.ctvss3zt8.8","DOIUrl":"https://doi.org/10.2307/j.ctvss3zt8.8","url":null,"abstract":"This chapter explores how the very evident departures from Albert Einstein's homogeneity—stars in galaxies in groups and clusters of galaxies—might have formed in an expanding universe. In the established cosmology, cosmic structure formed by the gravitational instability of the relativistic expanding universe. The early confusion about the physical meaning of this instability is an important part of the history. The chapter reviews these considerations, along with assessments of early scenarios of how cosmic structure might have formed. A theory of how the galaxies formed in the big bang cosmology has to provide a physically consistent picture of how cosmic structure evolved from the very different conditions in the early stages of expansion. That consideration is absent in the 1948 steady-state cosmology, so thinking about structure formation had to be different.","PeriodicalId":211035,"journal":{"name":"Cosmology’s Century","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115129389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This chapter examines two spatially homogenous world pictures which captured most of the attention in cosmology from the late 1940s through the mid-1960s: an evolving universe and a universe in a statistically steady state. The evolving model describes expansion according to general relativity from an exceedingly dense early condition often termed the big bang. In the big bang model, a straightforward extrapolation of its evolution back in time ends at a singularity: a manifest failure of standard general relativity. In the alternative world picture, the continual creation of matter keeps the near-homogeneously expanding universe in a steady state. It lacked Albert Einstein's endorsement, but skillful proponents kept the picture visible in England though generally less so at other research centers. The steady-state cosmology is much more predictive than the big bang, which might have been expected to have added more than it did to general interest in the model.
{"title":"Cosmological Models","authors":"J. Uzan","doi":"10.2307/j.ctvss3zt8.6","DOIUrl":"https://doi.org/10.2307/j.ctvss3zt8.6","url":null,"abstract":"This chapter examines two spatially homogenous world pictures which captured most of the attention in cosmology from the late 1940s through the mid-1960s: an evolving universe and a universe in a statistically steady state. The evolving model describes expansion according to general relativity from an exceedingly dense early condition often termed the big bang. In the big bang model, a straightforward extrapolation of its evolution back in time ends at a singularity: a manifest failure of standard general relativity. In the alternative world picture, the continual creation of matter keeps the near-homogeneously expanding universe in a steady state. It lacked Albert Einstein's endorsement, but skillful proponents kept the picture visible in England though generally less so at other research centers. The steady-state cosmology is much more predictive than the big bang, which might have been expected to have added more than it did to general interest in the model.","PeriodicalId":211035,"journal":{"name":"Cosmology’s Century","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125560354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"PREFACE AND ACKNOWLEDGMENTS","authors":"","doi":"10.2307/j.ctvss3zt8.3","DOIUrl":"https://doi.org/10.2307/j.ctvss3zt8.3","url":null,"abstract":"","PeriodicalId":211035,"journal":{"name":"Cosmology’s Century","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128915779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This chapter looks at the change in the state of empirical cosmology in the five years from 1998 to 2003, which was great enough to be termed a revolution. It was driven by the two great experimental advances. The first is the measurement of the relation between the redshift of the spectrum of an object and its brightness in the sky, given its luminosity: the cosmological redshift–magnitude relation. The second is the detailed mapping of the angular distribution of the cosmic microwave background (CMB) radiation. The two programs reached the precision needed for significant constraints on cosmological models at essentially the same time. Quick acceptance of their interpretation was driven by the impressive consistency of implications of these two quite different ways to look at the universe and, equally important, by the consistency with other lines of evidence gathered in the years of research before the revolution.
{"title":"The 1998–2003 Revolution","authors":"P. Peebles","doi":"10.2307/j.ctvss3zt8.13","DOIUrl":"https://doi.org/10.2307/j.ctvss3zt8.13","url":null,"abstract":"This chapter looks at the change in the state of empirical cosmology in the five years from 1998 to 2003, which was great enough to be termed a revolution. It was driven by the two great experimental advances. The first is the measurement of the relation between the redshift of the spectrum of an object and its brightness in the sky, given its luminosity: the cosmological redshift–magnitude relation. The second is the detailed mapping of the angular distribution of the cosmic microwave background (CMB) radiation. The two programs reached the precision needed for significant constraints on cosmological models at essentially the same time. Quick acceptance of their interpretation was driven by the impressive consistency of implications of these two quite different ways to look at the universe and, equally important, by the consistency with other lines of evidence gathered in the years of research before the revolution.","PeriodicalId":211035,"journal":{"name":"Cosmology’s Century","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127624196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This chapter examines why in the early 1980s cosmologists co-opted the astronomers' subluminal mass and the particle physicists' nonbaryonic matter in what became known as the standard cold dark matter, or sCDM, cosmological model. The letter “s” might be taken to mean that the model was designed to be simple (as it was) but it instead signified “standard,” not because it was established but because it came first. A large part of the cosmology community soon adopted variants of the sCDM model as bases for exploration of how galaxies might have formed in the observed patterns of their space distribution and motions, and for analyses of the effect of galaxy formation on the angular distribution of the sea of thermal radiation. This widespread adoption was arguably overenthusiastic, because it was easy to devise other models, less simple to be sure, that fit what we knew at the time. And it was complicated by the nonempirical feeling that space sections surely are flat.
{"title":"The Age of Abundance of Cosmological Models","authors":"P. Peebles","doi":"10.2307/j.ctvss3zt8.11","DOIUrl":"https://doi.org/10.2307/j.ctvss3zt8.11","url":null,"abstract":"This chapter examines why in the early 1980s cosmologists co-opted the astronomers' subluminal mass and the particle physicists' nonbaryonic matter in what became known as the standard cold dark matter, or sCDM, cosmological model. The letter “s” might be taken to mean that the model was designed to be simple (as it was) but it instead signified “standard,” not because it was established but because it came first. A large part of the cosmology community soon adopted variants of the sCDM model as bases for exploration of how galaxies might have formed in the observed patterns of their space distribution and motions, and for analyses of the effect of galaxy formation on the angular distribution of the sea of thermal radiation. This widespread adoption was arguably overenthusiastic, because it was easy to devise other models, less simple to be sure, that fit what we knew at the time. And it was complicated by the nonempirical feeling that space sections surely are flat.","PeriodicalId":211035,"journal":{"name":"Cosmology’s Century","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127124126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This chapter studies the presence of “subliminal matter.” The presence of significant mass in subluminal matter was first suggested in the 1930s by the surprisingly large velocities of galaxies in clusters of galaxies. The chapter traces the history of discovery of astronomical evidence of subluminal matter in large clusters of galaxies, in groups of a few or just two galaxies that are close enough that they seem likely to be gravitationally bound, and in individual spiral galaxies. There must be enough mass in spirals to account for the circular velocities of disk stars, and the mass rotationally supported in the disk must be large enough that gravity can form spiral arms, but this mass component cannot be so large that the spiral arms grow to destroy the observed nearly circular motions in the disk. These conditions require that most of the mass in a spiral galaxy is in a stable subluminal massive halo draped around the outskirts of the luminous parts of the galaxy.
{"title":"Subluminal Mass","authors":"P. Peebles","doi":"10.2307/j.ctvss3zt8.9","DOIUrl":"https://doi.org/10.2307/j.ctvss3zt8.9","url":null,"abstract":"This chapter studies the presence of “subliminal matter.” The presence of significant mass in subluminal matter was first suggested in the 1930s by the surprisingly large velocities of galaxies in clusters of galaxies. The chapter traces the history of discovery of astronomical evidence of subluminal matter in large clusters of galaxies, in groups of a few or just two galaxies that are close enough that they seem likely to be gravitationally bound, and in individual spiral galaxies. There must be enough mass in spirals to account for the circular velocities of disk stars, and the mass rotationally supported in the disk must be large enough that gravity can form spiral arms, but this mass component cannot be so large that the spiral arms grow to destroy the observed nearly circular motions in the disk. These conditions require that most of the mass in a spiral galaxy is in a stable subluminal massive halo draped around the outskirts of the luminous parts of the galaxy.","PeriodicalId":211035,"journal":{"name":"Cosmology’s Century","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131561314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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