Biomedical subjects

J D Barrow

Publications and source records attributed to J D Barrow.

3 recordsLinked to original sources

PubMed2001

Further evidence for cosmological evolution of the fine structure constant.

We describe the results of a search for time variability of the fine structure constant alpha using absorption systems in the spectra of distant quasars. Three large optical data sets and two 21 cm and mm absorption systems provide four independent samples, spanning approximately 23% to 87% of the age of the universe. Each sample yields a smaller alpha in the past and the optical sample shows a 4 sigma deviation: Delta alpha/alpha = -0.72+/-0.18 x 10(-5) over the redshift range 0.5<z<3.5. We find no systematic effects which can explain our results. The only potentially significant systematic effects push Delta alpha/alpha towards positive values; i.e., our results would become more significant were we to correct for them.

Journal Article↗

PubMed2001

Cosmology, life, and the anthropic principle.

We discuss some ways in which the age, size, and structure of the Universe, together with the values of its defining constants, satisfy the necessary conditions for life. The implications for teleology and the existence of other universes are also discussed.

Anthropology, Physical↗

PubMed1977

A chaotic cosmology.

An anisotropic, inhomogeneous cosmological model is proposed in which the inhomogeneity is generated by shear fluctuations. This is a sufficient condition for dissipative heating by collisional neutrinos to explain the present large heat content of the universe, S(b o) approximately 10(8), together with its isotropy and comparative homogeneity on large scales when the photons were last scattered. The model does not require the chaotic motions to be arbitrarily truncated on large scales and isotropises early enough with high entropy to ensure the synthesis of light elements with the observed abundancies. A population of black holes which arises in a natural way can also provide the necessary ingredients for a theory of galaxy formation and morphology. The 10(15)-g black holes, predicted by some authors, are not necessarily expected to be a feature of chaotic cosmologies.

Journal Article↗