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R. Barrett and P. P. Delsanto
but rejected the corollary of a hotter past and cooler future. In particular,
he rejected the idea of an initial singularity, which he jeeringly nicknamed
“big bang”, never suspecting that the term would soon become a hit, even
among the supporters of the FLRW model. Hoyle maintained that a steady
state universe could be compatible with the drifting apart of galaxies if,
due to a “creation field ”, new matter were spontaneously and continuously
generated in the intergalactic space. The amount of newly created matter
required to ensure the steady state condition was very little: approximately
one hydrogen atom per cubic kilometre per year. This is so small as to be
totally unobservable.
The steady state theory was thus based on the assumption of an unobservable phenomenon, and as such might be thought incompatible with what we
call “physics”. (Theories in physics should produce some predictions that are
capable of being verified or refuted experimentally, either directly, indirectly,
now or in the future.) Wolfgang Pauli, one of the greats of 20th Century
Modern Physics, disparaged untestable theories as “not even wrong". This, in
his eyes, was a far worse characteristic than being wrong, for the experimental
testing of wrong theories often leads to unexpected new breakthroughs.
However the Steady State Theory does predict observable differences with
the FLRW model. Newly discovered radio sources (quasars and radio galaxies)
were associated in the big bang theory with the early stages of the universe;
they were therefore expected to be found only at large distances.
From the Steady State Theory, these unusual new objects were expected to
be uniformly distributed throughout the universe. This disagreement between
the Steady State Theory and the FLRW model led Steven Weinberg to write
in 1972: “In a sense, this disagreement is a credit to the model; alone among all
cosmologies, the steady-state model makes such definite predictions that it can be
disproved even with the limited observational evidence at our disposal [4].”
The steady state theory was finally swept away by new observational
evidence emerging in 1964 and analysed and perfected afterwards: namely,
the relic radiation or cosmic microwave background (CMB), which we discuss
in the next Section. Hoyle’s reluctance to accept the demise of his theory
shows that even a front rank astrophysicist like Fred Hoyle may not be
immune from prejudices. 3
3 The Steady State Theory received a new incarnation in the Quasi-steady state cosmology (QSS)
proposed in 1993 by Fred Hoyle, Geoffrey Burbridge, and Jayant V. Narlikar. It was intended to
explain additional features unaccounted for in the initial proposal, but ran into further difficulties
and is not generally accepted.
R. Barrett and P. P. Delsanto
but rejected the corollary of a hotter past and cooler future. In particular,
he rejected the idea of an initial singularity, which he jeeringly nicknamed
“big bang”, never suspecting that the term would soon become a hit, even
among the supporters of the FLRW model. Hoyle maintained that a steady
state universe could be compatible with the drifting apart of galaxies if,
due to a “creation field ”, new matter were spontaneously and continuously
generated in the intergalactic space. The amount of newly created matter
required to ensure the steady state condition was very little: approximately
one hydrogen atom per cubic kilometre per year. This is so small as to be
totally unobservable.
The steady state theory was thus based on the assumption of an unobservable phenomenon, and as such might be thought incompatible with what we
call “physics”. (Theories in physics should produce some predictions that are
capable of being verified or refuted experimentally, either directly, indirectly,
now or in the future.) Wolfgang Pauli, one of the greats of 20th Century
Modern Physics, disparaged untestable theories as “not even wrong". This, in
his eyes, was a far worse characteristic than being wrong, for the experimental
testing of wrong theories often leads to unexpected new breakthroughs.
However the Steady State Theory does predict observable differences with
the FLRW model. Newly discovered radio sources (quasars and radio galaxies)
were associated in the big bang theory with the early stages of the universe;
they were therefore expected to be found only at large distances.
From the Steady State Theory, these unusual new objects were expected to
be uniformly distributed throughout the universe. This disagreement between
the Steady State Theory and the FLRW model led Steven Weinberg to write
in 1972: “In a sense, this disagreement is a credit to the model; alone among all
cosmologies, the steady-state model makes such definite predictions that it can be
disproved even with the limited observational evidence at our disposal [4].”
The steady state theory was finally swept away by new observational
evidence emerging in 1964 and analysed and perfected afterwards: namely,
the relic radiation or cosmic microwave background (CMB), which we discuss
in the next Section. Hoyle’s reluctance to accept the demise of his theory
shows that even a front rank astrophysicist like Fred Hoyle may not be
immune from prejudices. 3
3 The Steady State Theory received a new incarnation in the Quasi-steady state cosmology (QSS)
proposed in 1993 by Fred Hoyle, Geoffrey Burbridge, and Jayant V. Narlikar. It was intended to
explain additional features unaccounted for in the initial proposal, but ran into further difficulties
and is not generally accepted.