The truth is out there

So here I am, then, sitting in my hotel room in Copenhagen and drinking coffee, filling in time before I check out and travel to the airport for the journey home. I don’t have to be there until this afternoon so today is going to be a bit more leisurely than the rest of the week has been. It’s nice to get a couple of hours to myself.

It was an interesting little workshop, with lots of time for discussions, but lurking in the background of course was the question mark  over BICEP2. Many theorists have clearly been beavering  away on models which assume that BICEP2 has measured primordial gravitational waves and I suspect most of them really want the result to be correct. When I posted a message on Twitter about this, Ian Harrison posted this homage to a famous poster for the TV series The X-files. There’s more than a little truth in the comparison!


Whatever the truth about the BICEP2 measurements there’s no question that it’s a brilliant experiment, with exquisite sensitivity. There is no question that it has detected something so faint that it boggles the mind. Here is a slide from Phil Lubin’s talk at the meeting, which shows the unbelievably rapid improvement in sensitivity of microwave detectors:



I don’t think cosmologists ever pay enough credit to the people behind these technological developments, as it is really they who have driven the subject forward. In the case of BICEP2 the only issue is whether it has picked up a cosmological signal or something from our own Galaxy. Whatever it is, it’s an achievement that deserves to be recognized.

And as for the claims of the person responsible for the post I reblogged yesterday that the cosmic microwave background is a fraud, well I can assure you it is not. Any scientific result is open to discussion and debate, but the ultimate arbiter is experimental test. Several independent teams are working in competition on CMB physics and any fraud would be easily exposed. The cosmic microwave background is out there.

And so is the truth.

10 Responses to “The truth is out there”

  1. I’ve spoken to many theorists over the past few months, most of whom have been working on models that might be ruled out if BICEP were correct. Despite that, almost all of them would still like the result to be true. Physics is more interesting when you have a genuine unexpected experimental result to drive theory in new directions.

    • telescoper Says:

      Of course I understand that, and of course to some extent it’s necessary to believe in something, even just as a working hypothesis. The final word, though, belongs to the data..

      • Yes, we need theorists to be optimists and observers to be cynics!

      • telescoper Says:

        I’d say we should be radical when it comes to theory creation but conservative when it comes to data.

        These days the division between theory and observation is quite blurred: many people work at the interface. In this region you perhaps need to be some sort of linear combination of optimist and cynic…

      • Anton Garrett Says:

        Peter, please would you clarify “These days the division between theory and observation is quite blurred”? A century ago the guy who had the idea generally also did the experiment to test it, but I think you mean something else?

      • telescoper Says:

        I just meant that not long ago there were observational cosmologists and theoretical cosmologists and few people worked on both aspects. Now the big observational teams generally have people who work on theory too, largely though not exclusively doing simulation work. Very few jobs nowadays are in pure theory or pure observation. That’s a good thing, of course.

      • “These days the division between theory and observation is quite blurred”? A century ago the guy who had the idea generally also did the experiment to test it, but I think you mean something else?

        Having an idea for an experiment and doing it are both experimental things. These days, of course, big experiments have many people and might not get off the ground (in some cases literally) until after the person who had the idea has died. So that has changed, but again both aspects are experimental.

        In the old days of cosmology, Eddington, Einstein, de Sitter, Lemaitre, Friedmann, Tolman, Robertson etc were theorists. Probably none of them ever even looked through a telescope, at least not scientifically, i.e. nothing more than some VIP visiting an observatory would do. People like Hubble and Sandage were pure observers, painstakingly avoiding any theoretical interpretation (something expected—too much, in my view—of most observers these days). I met Lubos Kohoutek when I was in Hamburg (probably the only astronomer whose name appears in an R.E.M. [modern beat combo –Ed.] song), who was also such a pure observer. With stuff like Planck, you had folks like Efstathiou writing papers about it before it was launched. There was much more interplay between theory and observation when deciding how to build it. (Should we measure polarization?) People like Tegmark are theorists but work on the nitty-gritty of the raw observational data. Observers build an experiment to test specific theoretical predictions (compared to the general-purpose instruments of yore, such as the Hale and Hooker telescopes, the VLA etc). Yes, there are still pure theorists like Linde, and detector people who are very experimental, but most people probably have at least a bit of both.

      • Anton Garrett Says:

        Argent also had a track about the Coming of Cohomet Kohoutek.

      • In the R.E.M. song of the same name, Kohoutek, referring to the comet, is a metaphor for something which held promise, but then disappeared. Of course, as is the case with many comets, this one was discovered serendipitously. (There are comet hunters, of course. One was Messier, but he is known mainly for his list of non-comet objects (which he compiled so that he wouldn’t mistake them for comets).) Kohoutek worked mainly on planetary nebulae. He also discovered a large number of asteroids.

        There are actually several songs named after him (or, rather, the comet), including one by Sun Ra which I’m sure Telescoper will appreciate, since it is not by a modern beat combo but rather by an eccentric jazz man (appropriate, as cometary orbits are highly eccentric) with a celestial name, no less.

    • telescoper Says:

      Surely the least expected result would be no gravitational waves at all, cosmological or otherwise? That would demonstrate that we’ve misunderstood gravity at a very basic level…

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