the steady-state theory of the universe contents …on.br/cce/2013/br/lecture3.pdfwhitrow’s...

The steady-state

theory of the

universe

contents

&

contexts

H. Kragh,

Centre for Science Studies,

Aarhus University

The 1950s: is cosmology a respectable science?

The choice between cosmological models remains ”a matter for aesthetic

judgment” (Ernst Öpik, 1954).

Cosmology is a field where ”personal taste will greatly influence the choice

of basic hypotheses” (Oskar Klein, 1953).

”Cosmologists have always lived in a happy state of being able to postulate

theories which had no chance of being disproved” (Martin Ryle, 1953).

“Cosmologists are often in error, but never in doubt” (Lev Landau?)

T. Gold H. Bondi F. Hoyle

The steady-state

theory of the universe

The universe expands

eternally, with continual

creation of matter securing

a constant density of mass.

The Perfect Cosmological

Principle: On a very large

scale, the universe is

uniform both in space and

time.

Wm. McCrea J. Narlikar D. Sciama

Motivations behind the steady-state model

1. The time-scale problem

2. Creation in the past is an unscientific hypothesis

3. Relativistic cosmology is not a theory, but a supermarket of

theories (lack of uniqueness; little predictive power).

4. Only a unchanging universe guarantees that the laws of

physics are constant (repeatability of experiments).

Two early examples of uniform cosmological models.

W. de Sitter, 1931

“In general relativity a very wide range of models is available … The

number of free parameters is so much larger than the number of

observational points that a fit certainly exists.” (Bondi & Gold 1948)

O. Heckmann, 1932

The cosmological controversy: Not a controversy between Gamow (big bang)

and Hoyle (steady state), but between the steady state theory and relativistic

evolution theories.

The Hot Big Bang

In 1948-53, the Big-Bang model

was revived and greatly developed

by George Gamow et al. Their

work led to a “hot”, radiation-

dominated early universe,

calculations of primordially

produced elements, and a

prediction of a cosmic microwave

background (of T ≅ 5 K).

11th Solvay Congress 1958: Structure and evolution of the universe

Although the Solvay congress meant an acknowledgment of cosmology as part of

physics, it included no speakers supporting physical (big bang) cosmology in the style

of Gamow. Of the 12 addresses, 7 were astronomical/astrophysical and 3 were given

by steady-state advocates.

IAU conference, Berkeley 1961

”We admit we are fighting an up-hill battle.”

The perfect cosmological principle

”My guiding principle is … that the Universe in its

essence has always been what it is now: matter,

energy, and life have only varied as to shape and

position in space.”

Svante Arrhenius 1908

”The universe … is not only homogeneous, but also

unchanging on the large scale.”

H. Bondi & T. Gold 1948

Space curvature k = 0 (flat space)

Exponential expansion: R ~ exp(Ht), H constant

Deceleration parameter q0 = -1

Matter density ρ = ρcrit ≈ 5 × 10-28 g cm-3

Matter creation rate = 3ρH ≈ 10-43 g s-1 cm-3

Age of universe: infinite

Average age of galaxies <t> = T/3 ≈ 6 × 108 y

(T ≡ 1/H)

2

22

0

/

RH

dtRdq

Predictions of classical steady-state theory, ca. 1950

A chapter in the history of cosmology

including instructive discussions of

philosophical aspects, and involving scientists

(H. Bondi, T. Gold, G.C. McVittie), philosophers

(R. Harré, A. Grünbaum, N. Russell Hanson), as

well as scientist-philosophers (G.J. Whitrow, H.

Dingle, M. Bunge, R. Schlegel).

The steady-state controversy

”A scientific theory, to be useful, must be testable and vulnerable”

”The steady state model is the one that can be disproved most easily by

observation. Therefore, it should take precedence over other less

disprovable ones until it has been disproved.”

Non-empirical testing:

Does the SS theory lead to consequences that are

contradictory, or highly bizarre?

Whitrow’s paradoxes

1. Infinitely many causally unconnected galaxies that at all

times are empirically unknowable.

2. Infinitely many supermassive galaxies that grow by

accretion of new matter and violate cosmological principle.

3. An infinite past contains actual infinities and is

therefore ruled out (past eternity ≠ future eternity).

Cosmological tests, ca. 1948-1966

1. Time-scale problem

2. Redshift-magnitude relationship

3. Angular diameter-redshift relationship

4. Nucleosynthesis (He and heavier elements)

5. Radio-astronomical source counts

6. Formation of galaxies

7. Cosmic microwave background

7. Logical and methodological arguments

Hubble’s constant

& the time-scale

problem

H = 500 km/s/Mpc

T = 1/H = 1.8 Gy

Lemaître 1927 H0 ≅ 625 km/s/Mpc

Hubble 1931 H0 ≅ 558 km/s/Mpc

WMAP 2010 H0 = 70.1 km/s/Mpc

Sandage et al. 1956:

q0 = 2.5 ± 1

”the steady-state

theory does not fit

the real world.”

Palomar 200-inch Hale telescope

A. Sandage, ”Cosmology: a search for two

numbers,” Physics Today 23: 34-41

Cosmological tests,

1956-64,

magnitude-redshift:

favour evolutionary models

with q0 ≈ (½ …1), but do not

unambiguosly rule out

steady-state model.

m - M ≈ 5 log(cz) + (1 – q0)z

Angular diameter-redshift test

The relation between apparent angular

diameter and redshift depends on q0 and

can therefore be used as a cosmological

test (Hoyle 1958). However, …

log N(S) = const – 1.5 log S

Radio astronomy (Cambridge; Sydney)

Ryle et al. 1955

Ryle et al. 1966

The mass gap problem

How to produce nuclei with A > 8?

Triple alpha (3 12C) not possible.

Fermi (1949): ”This theory is incapable of explaining

how the elements have been formed.”

The 1948 prediction of a cosmic microwave background

R. Alpher & R. Herman, ”Evolution of the universe,” Nature 162 (1948), 774-75.

1965: Discovery of the cosmic microwave background (predicted by R. Alpher and R. Herman in 1948, T ≈ 5 K)

A. Penzias & R. Wilson

Standard hot-big-bang cosmology (1965+)

R. Dicke

J. Peebles

Y. Zel’dovich

Ca. 1970: A new paradigm of

cosmology (hot big bang).

Growing institutionalisation

etc.

QSSC (quasi steady-state cosmology)