COBE and after…

An item on the BBC website yesterday reminds me that it is twenty years since the announcement, in April 1992, of the discovery of temperature variations across the sky in the cosmic microwave background radiation by the Cosmic Background Explorer (COBE). Was it really so long ago?

At the time the announcement was made as I actually in the USA. In fact,  I was at the University of Kansas for about a month working on this paper with Adrian Melott and Sergei Shandarin, which eventually came out early in 1993. I remember it very well because we started the project, did all the calculations and wrote up the paper within the short time I was there. Oh what it is to be a postdoc, having only research to think about and none of the other distractions that come with more senior positions.

Anyway, the COBE announcement hit the news while I was there and it got a lot of press coverage. I even did a TV interview myself, for a local cable news channel. Nor surprisingly, they were pretty clueless about the physics of the cosmic microwave background; what had drawn them to the story was George Smoot’s comment that seeing the pattern of fluctuations was “like seeing the face of God”. They were disappointed when I answered their questions about God with “I don’t know, I’m an atheist”.

The Face of God?

I didn’t know at the time that the way the announcement of the COBE discovery was handled had caused such ructions. Apparently George Smoot let his enthusiasm get the better of him, broke ranks with the rest of the COBE team, and did his own press conference which led to accusations that he was trying to steal the limelight and a big falling-out between Smoot and other members of the team, especially John Mather. It’s unfortunate that this cast a shadow over what was undoubtedly one of the most important science discoveries of the twentieth century. Without COBE there would have been no WMAP and no Planck, and our understanding of the early Universe and the formation of galaxies and large-scale structure would still be in the dark ages.

As a lowly postdoc at the time, living a hand-to-mouth existence on short-term contracts, I didn’t realise that I would still be working in cosmology twenty years later, let alone become a Professor.  Nor could I have predicted how much cosmology would change over the next two decades. Most of all, though, I never even imagined that I’d find myself travelling to Stockholm as a guest of the Nobel Foundation to attend the ceremony and banquet at which the 2006 Nobel Prize for Physics was awarded to George Smoot and John Mather for the COBE discovery. It was a wonderful one-in-a-lifetime experience, made all the nicer because Smoot and Mather seemed to have made peace at last.

Where were you when the COBE results came out?

10 Responses to “COBE and after…”

  1. Lung-Yih Chiang Says:

    Smoot was making prediction and the “face of god” later turns out to be the initials of Stephan Hawking…..

  2. Try 3 to post! What has changed??

  3. Sorry about that….

    I just blogged about the ZX Spectrum being 30 years old (and that experience played a big role in me becoming an astronomer). But I remember COBE. Mildly hungover as a student in Cambridge, I trundled from King St to the Grafton Centre with friends to get food and a newspaper. The front cover said it all

    I thought it was a Saturday, but it appears to have been a Friday (ah, the joys of being a grad student).

    Smoot came to Cambridge soon after and gave a talk. We all trundled down to the old DAMPT to find out the story 🙂

    • Bryn Jones Says:

      Ah, yes. I still have somewhere a copy of that front page of the Independent newspaper reporting the COBE news conference at which the results were announced to the public. It was unusual in those days for serious newspapers to devote a large part of their front pages to any one story and it was excellent to see so much coverage of a scientific story.

  4. “Where we you when the COBE results came out?”

    I had just started my master’s thesis work in Sjur Refsdal’s group at the Hamburg Observatory.

  5. Andrew Liddle Says:

    In doing some research for the BBC article, I was interested to find that the original NASA press release is still available online

    Isn’t it also true that the image you include, which was widely used at the time, is in fact a pure noise map from subtracting the two detector signals from each other? I think this was used in order to show that the noise level was less than in the summed channel maps, letting the extra noise in those be interpreted as CMB anisotropies, and in which of course the galaxy prominently appears also.

    I was at a long-term workshop in the US at Santa Barbara when the result came out. There was a very high profile cosmology meeting at UC Irvine the month before, organised by David Schramm and co, where hints that something would be announced started to come through, but they managed to keep the actual result a very good secret.


    • telescoper Says:

      As far as I can remember the original COBE paper simply reported the detection of “excess variance” in the CMB. The signal to noise ratio was about unity in the maps that were presented, so you couldn’t point to specific features and state that they were signal or noise with any particular confidence.

      • John Peacock Says:

        A lot of people at the time, and for a long while thereafter, made great play of the fact that COBE didn’t detect individual real features. This is all a question of scale. At native 6 degree resolution, yes the pixels were individually quite noisy. But then the real scale of detailed features in the CMB is 1 degree, so no amount of S/N would have helped. However, the great thing about the CMB is that there is signal on all scales, and the large-scale part of this comes out if you smooth away the pixel noise. There’s a comparison somewhere of WMAP and COBE both smoothed to 20-degree resolution, and the features pretty well match up. So in my view they were always detecting true large-scale features, not just statistics.

        I was sitting in the VAX room at Meudon when Jean-Michel Alimi burst in with the news. It’s hard to think of any time when I felt the landscape of science changed in quite such a historic way.

  6. Wasn’t the Astronomer Royal (Prof. Arnold Wolfendale) visiting the department in Cardiff that day Bryn? I’m pretty sure he spent most of the day doing tv & radio interviews rather than whatever he’d come to our department to do.

    • Bryn Jones Says:

      I don’t know, Rhodri, I wasn’t there. I left Cardiff for Cambridge some time before and didn’t return to Cardiff until later.

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