Authors: Kitty Ferguson
In the 1930s, many astronomers and theoretical physicists were taking Hubble’s observations as direct evidence that the universe is expanding, but resistance to the idea had not ended and it was not all from within scientific circles. As was the case with Newton’s
Principia
, the public were aware of stupendous changes going on in science. Einstein’s theories were popularized in many forms and his name became a household word. When a new discovery or theory is fundamental enough to impinge on everyone’s concept of the universe and reality – not just a few specialized scientists – there tends to be a feeling that others besides scientists should have a say about what is True in this matter.
Nearly everyone who reads popular science books remembers that Einstein didn’t like the idea of an expanding universe. Fewer are aware of the ugly opposition from some who held political power. In 1936, in the Soviet Union, Joseph Stalin
began
a purge of scientists whose scientific findings and conclusions were not politically correct. One of the forbidden ideas was that the universe was expanding.
In his book
Fireside Astronomy
, British astronomer Patrick Moore tells of the experiences of his friend Nikolai Kozyrev. Kozyrev was an astrophysicist at the Pulkovo Observatory near St Petersburg. In November 1936 he was arrested and physically assaulted. In May 1937 he came to trial. What his offence was was never clearly stated, but he was sent to prison. After two years Kozyrev ended up in a labour camp, and there a fellow prisoner reported him for holding scientific views about an expanding universe that were contrary to Soviet doctrine.
Kozyrev was resentenced to 10 years’ imprisonment. When he appealed, the sentence was changed to death. There was no firing squad at the labour camp, and a second appeal got the sentence reduced again to 10 years. Gregory Shain, later the Director of the Crimean Observatory, rescued Kozyrev from this appalling situation. He managed to get him transferred to Moscow in 1945 and saw him set free in 1947. Kozyrev returned to his work in astrophysics, having lost 10 years. Other Soviet scientists were less fortunate. Many were executed. The persecution even extended to the scientists’ families. Kozyrev’s wife was imprisoned, though not for such a long period as her husband.
Elsewhere the opposition was less extreme, and it soon focused not so much on whether the universe was expanding as upon whether it had a beginning. It was here that discoveries in astronomy and physics theory trod most seriously on philosophical and religious sensibilities.
One interpretation of Galileo’s trial sees it as a clear contest between the authority of religion and the authority of science. In the 20th century, those who had thought science had won that contest long ago were chagrined to find science seeming to uphold a religious point of view. Anyone for whom the idea of a
God
was anathema now had to face the unthinkable: a beginning . . . a moment of choice about whether there would be a universe . . . a creator.
Not that all who found the Big Bang philosophically disquieting were self-declared atheists. Many men and women, often without giving much thought to whether this conflicted with their religious beliefs, had put their trust in the power of science to explain the world. Since the time of Newton it had been a growing assumption both in and out of science that scientific laws and explanations underlie everything that occurs, even those things that remain most mysterious and hidden, and that, given time, human minds ought to be able to discover those laws and explanations. The Big Bang threatened that cherished assumption.
A passage from Robert Jastrow’s 1978 book
God and the Astronomers
sums up the situation. Jastrow is himself an astronomer and an agnostic, but he chides his colleagues for their reaction: ‘the response of the scientific mind – supposedly a very objective mind – when evidence uncovered by science itself leads to a conflict with the articles of faith in our profession’. He goes on to say:
This is an exceedingly strange development, unexpected by all but the theologians. They have always accepted the word of the Bible: In the beginning God created heaven and earth. To which St Augustine added, ‘who can understand this mystery or explain it to others?’ The development is unexpected because science has had such extraordinary success in tracing the chain of cause and effect backward in time . . . Now we would like to pursue that inquiry farther back in time, but the barrier to further progress seems insurmountable. It is not a matter of another year, another decade of work, another measurement, or another theory; at this moment it seems as though science will never be able to raise the curtain on
the
mystery of creation. For the scientist who has lived by his faith in the power of reason, the story ends like a bad dream. He has scaled the mountains of ignorance, he is about to conquer the highest peak; as he pulls himself over the final rock, he is greeted by a band of theologians who have been sitting there for centuries.
Three Cambridge physicists declined the invitation to sit down with the theologians. Just as there had been excellent alternative ways of explaining Galileo’s findings without having to have a moving Earth (Tycho Brahe’s model, for example), there were excellent alternative ways of explaining Hubble’s and Einstein’s without having to have a beginning.
In 1948 Hermann Bondi and Thomas Gold, both originally from Austria, and Fred Hoyle introduced theories that allowed the expansion of the universe to happen without requiring that the universe have a beginning in time. Their ‘Steady State’ theory became the Big Bang’s major competitor. According to Bondi, Gold and Hoyle’s proposal, the universe hasn’t always contained all the matter that is in it today. As the universe expands, new matter emerges to fill in the broadening gaps, and the average density of matter in the universe remains the same. While the stars in a galaxy like ours burn out and the galaxy dies, new galaxies are forming from the new matter. There would be no beginning or end to a Steady State universe. The unwelcome hint of ‘creation’ suggested by Big Bang theory would be eradicated.
For at least two decades, the scientific and philosophical debate went on between those who favoured one theory and those who insisted on the other, until finally, in the 1960s, new evidence came to light that Steady State theory could not explain and Big Bang theory actually had predicted. It should come as no surprise that Hoyle, one of the inventors of Steady State theory, was the author of one of the most insightful books about the Copernican revolution, a book with considerable
sympathy
for Ptolemy that points out clearly how
both
Copernicus and Ptolemy were correct.
The observational evidence that weighed in so heavily in favour of the Big Bang was not evidence from an optical telescope. By then astronomers had discovered that the old phrase ‘I won’t believe it until I see it’ represented a ridiculously limiting attitude. Most of what goes on in the universe can’t be ‘seen’ at all. It happens beyond the visible range of the spectrum.
It was no coincidence that studies of the heavens were for centuries only studies of visible light, and that radio astronomy was the first new astronomy to emerge. In only those two parts of the electromagnetic spectrum – the optical and radio ranges – are there wavelengths that can pass through the Earth’s atmosphere. Radiation in the infrared range can reach as low as the highest mountains. The Earth’s atmosphere blocks other radiation. Study of ultraviolet rays, X-rays and gamma rays coming from space can’t be done at all without telescopes above the atmosphere. It wasn’t possible to put them there until the late 1950s.
Radio astronomy began a quarter of a century before that, almost by accident. In the 1930s, trans-Atlantic phonecalls took place by radio transmission and were plagued by static. The task of finding out what was causing the static fell to Karl Jansky of the Bell Telephone Laboratories in Holmdel, New Jersey. Jansky built a special radio antenna – a long array of metal pipes – to aid him in his investigation.
As Jansky sorted out the static, he found that most of it came from thunderstorms, but there was also a faint hissing static that couldn’t be so easily explained. The hiss was strongest when the region of the sky in the direction of the constellation Sagittarius was overhead. The central regions of our Galaxy lie in that direction. When this part of the sky was below the horizon, the hiss was weaker but it never disappeared entirely. The expectation prior to Jansky’s discovery had been that the Sun would be
the
strongest source of radio waves in the sky, just as it is the brightest source of light. Now it seemed that a source could be very ‘bright’ in another part of the spectrum but show up not at all in terms of visible light. Jansky knew he had discovered the centre of the Galaxy. What else was out there that we were missing?
Though it might seem that such a mystery as Jansky’s hiss would have made headlines, his work received little attention even within the astronomy community. The one exception to this apathy was Grote Reber, an eccentric bachelor and ham radio operator in Wheaton, Illinois, who read about Jansky’s radio hiss in
Popular Astronomy
magazine. Reber proceeded to cash in his savings and design and construct his own device in his mother’s back yard to listen to radio signals coming from the sky. Reber’s telescope was a dish 30 feet (nine metres) in diameter. Astronomer Jesse Greenstein of Yerkes Observatory, when he later saw the back-yard telescope, called Reber ‘the ideal American inventor. If he had not been interested in radio astronomy, he would have made a million dollars.’
In the 1940s, Greenstein tried to get Reber a position at the University of Chicago. That fell through when the University agreed to have Reber only if his pay and research support came from Washington, and Reber refused to go to the bother of explaining to bureaucrats precisely how the money for new telescopes would be used. Except for Reber, until the 1950s there was virtually no interest in radio astronomy in the United States.
Astronomers elsewhere in the world were quicker, after the development of radar during World War II, to appreciate the potential advantages of studying radiation in a part of the electromagnetic spectrum outside the visual range. In 1946 a radar signal was bounced off the Moon, and in the years that followed, the Jodrell Bank radio telescope in England led the world in mapping radio sources in space. Following close behind were Cambridge University and a team in Australia.
Particularly
intense sources of radiation in the radio range of the spectrum became known as ‘radio stars’ and ‘radio galaxies’.
A problem in early radio astronomy – and one reason it drew little interest at first from optical astronomers – was that radio telescopes like Reber’s couldn’t measure a source’s position in the sky accurately enough to find out which visible object was emitting the radio waves. In order to accomplish that, there needed to be a hundred-fold improvement in resolution, and that meant a telescope about a kilometre in diameter. Radio waves come in a large range of lengths, but they are all longer than waves in the visible part of the spectrum, and their length is the problem. A radio telescope doesn’t give good resolution unless it is quite a bit larger than the length of the radio waves it’s receiving. Studying shorter radio waves only helps a little. The much shorter waves in the
visible
part of the spectrum allow optical telescopes to achieve resolution with relative ease. Radio astronomers finally solved this problem in 1949 by using networks of small telescopes linked to a receiving station which combines the signals. Such a network or array is a ‘radio interferometer’.
England and Australia continued to dominate the field. In 1950 Martin Ryle of Cambridge University and his co-workers discovered evidence of radio emissions from four nearby galaxies including Andromeda. Ryle was an advocate of Big Bang theory, and as he and his colleagues continued to map the distribution of radio sources across the sky, their findings supported that theory. They discovered that radio galaxies are much more abundant in the far distance than they are nearby. Since the further we peer into space the further back in time we are looking, Ryle’s radio telescopes were showing him the universe at a much earlier stage, and his discovery indicated that the density of radio galaxies was greater then than it is today. It’s reasonable to think this should be the case if this is an expanding universe in which everything on the large scale is
moving
away from everything else and used to be much more closely crowded together.
In 1954, owing largely to the influence of Greenstein, by then a professor at the California Institute of Technology, the National Radio Astronomy Observatory was built in West Virginia and a radio interferometer was constructed near Yosemite National Park in California under the aegis of Cal Tech. But before that, even during the years when radio astronomy was virtually nonexistent in the United States, the Bell Telephone Company had continued to carry on research having to do with radio communications. It was at Bell Labs in New Jersey, where Jansky had first investigated the radio hiss from space in the 1930s, that the discovery took place that most scientists considered the clincher for the Big Bang theory.
Arno Penzias was born to a Jewish family in Munich. When he was six years old, he and his brother and parents were among the last Jews to get out of Nazi Germany, arriving as impoverished immigrants in the United States in the winter of 1940. Penzias received his undergraduate physics degree from the City College of New York and went on to Columbia University for his PhD. In 1961 he took a job at Bell Labs, where two years later he was joined by Texan Robert Wilson. Wilson had at first favoured the Steady State theory over the Big Bang. He was strongly impressed with Fred Hoyle, who had been a visiting professor at Cal Tech when Wilson was a graduate student there. In 1963, a year after completing his PhD, Wilson crossed the country to the east coast to work at Bell Labs.
At Bell there was a large, horn-shaped antenna designed for use with the Echo I communications satellite. In the spring of 1964, Penzias and Wilson were using the antenna to study noise levels that were hampering the satellite’s transmission. Scientists working with the antenna had to make adjustments and limit themselves to signals that were stronger than the ‘noise’. It was an annoyance that was possible to ignore, but Penzias and
Wilson
chose not to. They noticed that the noise remained the same regardless of which direction they pointed the antenna. If the Earth’s atmosphere itself were the source of the noise, an antenna pointed towards the horizon should pick up more noise, for it faces more of that atmosphere than an antenna pointed straight up. Penzias and Wilson concluded that the noise had to be coming either from beyond the Earth’s atmosphere or from the antenna itself. Pigeons nesting in the antenna were evicted and their droppings cleared away. That didn’t help.