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Cosmologists around the world were caught off guard when NASA announced
in April last year that its Cosmic Background Explorer satellite had detected
very small variations in the intensity of the background microwave radiation
coming from different parts of the sky. Rumours had been rife that the
COBE team might be about to make an announcement, but they still managed
to surprise the world with their discovery, which was based on data that
had remained secret since the previous September.

In this age of electronic mail, scientists chat to each other daily
over global computer networks. Usually they hear the scientific news before
it is announced to the media, but not this time. The first inkling most
of us had of the breakthrough came, as it did to everyone else, via the
wires of the international press agencies. This was the beginning of an
exciting few weeks.

A testing day

The day of NASA’s announcement, Thursday 23 April, was an especially
testing one for many astronomers because they had to respond off the cuff
to questions from journalists, without knowing the details of the COBE findings.
What happened to me was typical of the experiences of other specialists
around the world, though for reasons that will become clear, British media
coverage of the event was particularly frenzied.

At 11 am that Thursday morning, Susan Watts, the science and technology
correspondent of The Independent, rang me about a story coming in ‘over
the wires’. The COBE team were to announce the discovery of ripples in the
background radiation in a news conference at 4 pm. I knew nothing about
it, of course. The press agency report she read out was full of hype: ‘the
discovery of the century, perhaps of all time’, ‘the Holy Grail of cosmology’,
‘English does not have enough superlatives’, ‘a certain Nobel prize’. But
there was also the crucial piece of information that temperature fluctuations
of 30 microkelvins had been seen when regions 500 million light years apart
were studied. This detail was enough to reconstruct what the COBE team were
about to announce, and over the following hour or so I was able to explain
the story to her.

In fact, the hype was unnecessary. This was a major story and NASA did
not have to exaggerate it. The microwave background radiation gives us a
snapshot of the Universe 300 000 years after the big bang, when the ‘fireball’
phase ended and matter decoupled from radiation. Ever since this background
was first discovered, in 1965, observers have been hunting for fluctuations
in it. Each time they improved the accuracy with which they measured the
evenness of the background radiation from all parts of the sky, theoreticians
were forced into ever more exotic explanations of how galaxies could have
formed by the action of gravity on such an initially smooth Universe.

Ten years ago they were forced into the fateful step of assuming that
for galaxies and clusters of galaxies to have evolved into their present
form, the Universe must be dominated by some form of exotic ‘dark matter’
that would leave no imprint on the microwave background. The gravity of
the lumps of dark matter would then gather the ordinary matter together
to make galaxies.

There are two versions of what this dark matter could be. The version
which appeared to work best at explaining the distribution of galaxies we
see today envisages cold dark matter, composed of hypothetical particles
with names such as ‘axions’ or ‘photinos’, which would be slow-moving (hence
‘cold’) in the early Universe. Alternatively, if the particles were neutrinos
with a small but non-zero mass, they would be moving close to the speed
of light in the early Universe, and would thus constitute ‘hot’ dark matter.

At about the same time as cosmologists realised they needed dark matter,
particle physicists introduced the dramatic new concept of inflation into
the big bang theory. They suggested that soon after the big bang the Universe
went through a phase of rapidly accelerating expansion, which inflated
it 1070 times – from much smaller than the size of an atom to about the
size of a tennis ball.

The inflationary scenario also required the Universe to be composed
mainly of dark matter. Before 23 April 1992, the limits within which the
microwave background was known not to vary were getting close to the values
predicted in this picture. The COBE discovery confirmed that dark matter
is, after all, needed to make galaxies, though it does not tell us precisely
how much dark matter there is, and certainly does not imply that the Universe
will end in a big crunch, as several newspaper reports insisted.

Natural sequel

That Thursday, the phone continued to ring. At 4 pm Tim Radford, the
science editor of The Guardian, phoned from Edinburgh. Like most of Britain’s
science correspondents, he was covering the Edinburgh Science Fair and a
debate about science and religion between the biologist and science writer
Richard Dawkins and John Habgood, the Archbishop of York. This debate, although
of course inconclusive, was given wide coverage in the British media. The
ripples story, in apparently penetrating to the very birth of the Universe,
seemed like a natural sequel, hence the frenzied British media coverage.
Tim said that The Guardian would have the story on its front page.

Someone from Sky TV rang and asked me to appear on the Breakfast News
programme the next day. He asked me to provide some pictures and sent a
motorbike to my home later in the evening to pick them up.

Later I heard that most cosmologists in Europe and the US had the same
kind of day. At the Space Sciences Laboratories of the University of California
at Berkeley, the base of George Smoot, one of the COBE investigators, newspaper
and TV reporters laid siege. As Smoot was in Washington taking part in
the press conference, the graduate students were the ones that gave the
interviews.

At 6.45 am the following day, the car from Sky arrived. On the way to
the studio I read The Independent: it had the most wonderful front page
spread on ‘How the Universe began’, a piece based mainly on my conversation
with Susan Watts in which I was quoted extensively and reasonably accurately.

The driver had the Daily Mail on the back seat, so I checked that too.
Amazingly, in such a short time, it had managed to get pieces on the COBE
results by popular astronomer Patrick Moore, presenter of BBC TV’s The Sky
at Night, and celebrated astrophysicist Stephen Hawking. The driver asked
me what I was going to Sky for. I held up The Independent front page and
said: ‘For this, how the Universe began.’ He said that he had thought as
much; he’d heard about the story on the radio and guessed that this was
why he was picking up a professor. He asked what the story was about and,
realising that this was a good opportunity to practise what I was planning
to say later, I tried to explain things. His only comment was that it
didn’t sound very much like the account given in Genesis.

At 8.15 am I did my bit, preceded by the secretary of the British Tall
Persons Club and followed by a beekeeper. I was impressed by the professionalism
of the news presenters, who maintained a serene momentum while working at
a desk covered with a jumble of bits of paper and newspapers. The pictures
came up in some arbitrary order chosen by the producer and I talked around
them. It was a bit nerve-racking saying ‘I think we have a picture here
of the telescope with which the microwave background radiation was discovered’
while wondering whether it would actually appear.

Back in my office at Queen Mary and Westfield College, on the opposite
side of London, I had a phone call from Susan Watts of The Independent.
I congratulated her on the story. She was doing a follow-up on the significance
of the COBE ripples and what would happen next, and told me that there would
be a companion piece on their religious significance. My relief at not being
part of that piece was short-lived. The Daily Telegraph rang, interested
mainly in ‘the religious aspect’. Its photographer came round later and
spent hours taking photographs, practically demolishing my office in the
process. Robin McKie, science correspondent of The Observer, called. He
was doing a story about how COBE means the Universe will end in a big crunch.
I couldn’t think where he got this notion from and spent half an hour trying
to convince him otherwise.

Turning to my computer, I learnt from the messages that were circulating
on the electronic grapevine that the COBE team had tried to eliminate sources
of error in the readings of background radiation by making an extremely
careful analysis of the possible sources of foreground noise, including
telemetry problems, radio interference, the Moon, dust, gas and cosmic rays
in the Milky Way. The image released by NASA showed the whole sky projected
onto an elliptical area, with the bright foreground Milky Way emission across
the horizontal axis, looking distinctly like the meat in a hamburger. The
blotchy patches in the bun of the hamburger were meant to be a highly exaggerated
representation of the fluctuations, or ripples. The typical deviations from
the average brightness are only one part in 100 000, and the variations
in density of ordinary matter in the primeval Universe would have been of
the same order. From such inauspicious beginnings have we evolved, with
an average density of about 1 gram per cubic centimetre, or 1030 times the
average in the Universe today.

It turned out, though, that NASA’s maps were quite badly affected by
instrument noise, and only some of the blotches were due to the Universe.
This did not reduce the significance of the COBE discovery but it was a
pity that the NASA press office felt that a picture had to go out with their
press release, even if it was, to say the least, uninformative and perhaps
misleading. Several months later, the BBC’s Antenna programme did a piece
on how the COBE ripples story was covered, which gave the impression that
the discovery was not very important and that the coverage of it was pure
hype. That programme, which set out to expose media distortion of science
stories, was itself quite a severe distortion of the ripples story.

At 6 pm on the Friday there was a party at the London Planetarium to
celebrate the 35th anniversary of The Sky at Night, to which my wife Mary
and I went. Everyone was talking about the COBE ripples, of course. Moore
told us that he had written his Daily Mail piece in 40 minutes.

On Saturday 25 April, The Independent quoted me as saying that I follow
St Augustine and Hawking in believing time began with the Universe, and
The Daily Telegraph reported that I do not believe in God. Hawking was
quoted as believing the cosmic ripples to be the discovery of the century.
I assumed that he had been trapped into saying this by being fed the quotes
from the press agency report.

The following Monday, 27 April, I was back down to earth as the university
term started. I told the students on my third-year cosmology course about
the COBE results and their significance. Later Tim Radford of The Guardian
rang to ask if there were any further developments. I said I was thinking
of writing a more reflective piece about the significance of the discovery
and the press coverage, 1000 words, say. He was interested but said that
‘reflective’ for The Guardian meant that it had to be in by noon the next
day.

Inspection awayday

Two days later I was at the University of Durham as part of a team visiting
the university’s astronomy group on behalf of the Science and Engineering
Research Council. A three-member panel, of which I was a one, had the task
of assessing the group’s work and making recommendations about the level
of financial support it should have. This kind of assessment goes on all
the time; my own research grants had been similarly assessed earlier in
the year.

Two members of the group, the leader Richard Ellis, and Carlos Frenk
are good friends of mine and former col-laborators. Over lunch Carlos told
me he thought COBE presented a serious problem for the cold dark matter
theory, but that there might be a way out. He said that George Efstathiou,
another former collaborator, now working at the University of Oxford, favoured
a variation of the theory in which the Universe still has a significant
cosmological repulsion term; this is the force which drove inflation in
the very early Universe, and which has to be very weak today. I said that
I was still interested in the possibility of a hybrid Universe containing
hot and cold dark matter. Carlos was curious but sceptical.

Back in London the next day, Thursday 30 April, there was a preview
of the video of Hawking’s A Brief History of Time, organised by The Guardian.
At the reception beforehand I asked Hawking what he thought about the COBE
discovery; had he really said it was the discovery of the century? To my
surprise he said he really did think it was, and that he saw the discovery
as confirmation of the inflation scenario. He claimed that he had predicted
the shape of the density fluctuation spectrum, which COBE observed, from
inflation theory. What about Ted Harrison (of the University of Massachusetts),
I asked, and the late Yakov Zeldovich (of the former Soviet Academy of Sciences)
who had suggested this spectrum about ten years earlier? Hawking said they
predicted the spectrum from considerations of how galaxies and clusters
form, but that he is not interested in galaxies. I was stunned by this illustration
of how diametrically opposed we are in our world-views. For myself, and
most astronomers I think, to understand the origin of galaxies would seem
of far greater significance than speculations about the instant of the big
bang, which can probably never be tested.

Oracular style

I found the video moving, especially on a large screen. The opening,
with the sound of the clicking of Hawking’s hand-control as he prepares
a text, was very dramatic. The film brought out his concise and oracular
style very well. It was also good to see the other relativists who are part
of this story, though unhelpful that they were not identified.

Are the COBE ripples the discovery of the century? By no means, in my
view, but they are a landmark. To set them in perspective, it is worth recalling
the other great landmarks in 20th-century cosmology. First came the American
astronomer Edwin Hubble’s discovery of the expansion of the Universe in
1929. Then there was the invention of the hot big bang model by the Soviet
cosmologist George Gamow in 1948. Next came the discovery in 1965 of the
cosmic microwave background radiation by the American radio astronomers
Arno Penzias and Bob Wilson of AT&T Bell Laboratories. In 1972 came
the explanation of the abundances of the primordial light elements helium,
deuterium and lithium, by the American physicists Bob Wagoner and Willy
Fowler, and the British cosmologist Fred Hoyle. Finally, there was the discovery
of the motion of our Galaxy through the microwave background radiation in
1977 by George Smoot, David Wilkinson of Princeton University, and Francesco
Melchiorri, then at the University of Florence.

Of these, the seminal advance is clearly Hubble’s discovery of the expansion
of the Universe. Next in importance comes the discovery of the microwave
background radiation. The ripples rank with the remainder of the above list
(and perhaps others not on the list) in being important details, elaborating
the picture of the hot big bang expanding Universe.

What are the implications of the COBE team’s discovery? Before answering
this question, the COBE results need to be confirmed in other experiments.
This seems to have happened already. The results were based on the data
collected by the NASA team in its first year. The second year’s data are
already ‘in the can’, being analysed. If these give exactly the same map
of the sky, the results will look credible. The Soviet RELICT satellite,
which has also been mapping the microwave background radiation, has apparently
seen the same result as COBE on the largest scales. A balloon-borne experiment
led by Lyman Page of Princeton University, Stephen Meyer of the Massachusetts
Institute of Technology, and Ed Cheng of the Goddard Space Flight Center,
has directly confirmed the ripples seen by COBE. Phil Lubin of the University
of California at Santa Barbara has been running an experiment for over a
year at the South Pole with a sensitivity approaching that of COBE and seems
to have confirmed the discovery, as has also another ground-based experiment
by Rod Davies of Jodrell Bank, near Manchester, Anthony Lasenby of the University
of Cambridge, and their colleagues at the Canaries Institute of Astrophysics
on Tenerife.

It will be especially important to look with much bigger telescopes
than COBE’s to find the much smaller ripples which correspond to nascent
galaxies and clusters of galaxies. Because of the limited resolution of
the COBE detectors, the fluctuations found so far correspond to structures
much larger than anything we can actually map in the Universe today. But
on these large scales, the COBE team was able to analyse how the strength
of the fluctuations declined as we look to larger and larger scales, and
the rate of this decline agrees well with what is expected from models based
on inflation, such as the cold dark matter scenario. Although the agreement
between the COBE observations and the cold dark matter model is poor (there
is a discrepancy of about a factor of 2) the COBE discovery looks good
for the inflationary scenario and for a Universe dominated by dark matter.
And it is certainly great news for big bang cosmology. The failure to find
these density fluctuations in decades of searching had been one of the most
frustrating episodes in modern cosmology.

In August 1992, at a workshop in Erice, Sicily, I asked George Smoot
about his feelings concerning the international furore over the ripples.
I have known him since 1978, when I spent a year at Berkeley. I recall that
in June 1990, during a conference in The Hague, he and I had dinner at a
restaurant on the beach. We talked about many things, the anthropic principle
(the idea that our existence tells us something about the properties of
the Universe), whether there is other life in the Universe (I am unusual
among astronomers in believing that we are alone) and, of course, whether
COBE would detect the ripples. At that time, he was hopeful that over the
four years of the mission, it might have a chance of detecting them. I don’t
think he had any idea of the fame they would bring him.

At Erice, George’s comment was that the furore had, on balance, been
good for astronomy and for physics generally. Wherever he went, he said,
astronomers and physicists were telling him that the story of the ripples
had helped them in their struggle for resources. I had to agree with him.
Considering its significance in our lives, science receives very little
coverage on television or in the press. Stories like this are good for science.
However, I am irritated when scientists feel it necessary to try to make
their work more interesting to the public by talking, like Hawking, about
‘the mind of God’ or, as Smoot would have it, ‘the face of God’.

Michael Rowan-Robinson, formerly professor of astrophysics at Queen
Mary and Westfield College, London, is now professor of astrophysics at
Imperial College, London. This article is an edited extract from his latest
book Ripples in the Cosmos: A View Behind the Scenes of the New Cosmology,
which is due to be published in Britain on Monday, and in Australia next
February, by W. H. Freeman/Spektrum.