It has been proposal season for the Hubble Space Telescope, so many astronomers have been busy with that. I am no exception. Talking to others, it is clear that there remain many more excellent Hubble projects than available observing time.

So I haven’t written here for a bit, and I have other tasks to get on with. I did get requests for a report on the last conference I went to, Beyond WIMPs: from Theory to Detection. They have posted video from the talks, so anyone who is interested may watch.

I think this is the worst talk I’ve given in 20 years. Maybe more. Made the classic mistake of trying to give the talk the organizers asked for rather than the one I wanted to give. Conference organizers mean well, but they usually only have a vague idea of what they imagine you’ll say. You should always ignore that and say what you think is important.

When speaking or writing, there are three rules: audience, audience, audience. I was unclear what the audience would be when I wrote the talk, and it turns out there were at least four identifiably distinct audiences in attendance. There were skeptics – particle physicists who were concerned with the state of their field and that of cosmology, there were the faithful – particle physicists who were not in the least concerned about this state of affairs, there were the innocent – grad students with little to no background in astronomy, and there were experts – astroparticle physicists who have a deep but rather narrow knowledge of relevant astronomical data. I don’t think it would have been possible to address the assigned topic (a “Critical Examination of the Existence of Dark Matter“) in a way that satisfied all of these distinct audiences, and certainly not in the time allotted (or even in an entire semester).

It is tempting to give an interruption by interruption breakdown of the sociology, but you may judge that for yourselves. The one thing I got right was what I said at the outset: Attitude Matters. You can see that on display throughout.

IMG_5460
This comic has been hanging on a colleague’s door for decades.

In science as in all matters, if you come to a problem sure that you already know the answer, you will leave with that conviction. No data nor argument will shake your faith. Only you can open your own mind.

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10 thoughts on “Critical Examination of the Impossible

  1. Reading the title “Critical examination of the existence of [cold] dark matter”, before I saw your video I would perhaps have expected a critique from a particle physics viewpoint, as well as the cosmological viewpoint. Therefore if the organisers were set on this title they could have organised two linked talks: one given by a cosmologist and one given by particle physicist.

    Some obvious particle physics questions some of which you raised
    – Any LHC evidence for beyond standard model physics from LHC? Not yet
    – Any evidence from direct detection experiments? Not Yet
    – Would the existence of Dark Matter preclude a fundamental connection between charged elementary particles and gravitational fields? [with the possible corollary that all neutral particles are composite?].
    – Can gravitational fields arise from elementary particles in more than one way?
    – Assuming that dark matter can be created in Baryon-Baryon “super” collider collisions at some temperature in excess of that obtainable at the LHC (much greater than 10^17 Kelvin). If we assume that DM-DM and DM-Baryon collision cross-sections are very small, does this mean that the temperature distribution of dark matter created this way would be effectively fossilized at the time of the DM particle creation (i.e. fossilized from the very beginning of the universe)? Via this mechanism would the temperature distribution wide or narrow?

    Moving to Cosmology
    – From the Particle Physics evidence we have to assume that DM (if it exists) only interacts gravitationally with Baryons?
    – Since there is no particle physics evidence to tell us what the DM-DM collision cross-section might be, can cosmological observational constraints put a number to this?

    In a solely DM universe starting at the big bang with zero angular momentum and slight variations in initial density, and assuming negligible DM-DM collision cross-section, what happens? What happens then if we add Baryon’s to models by gradually increasing the Baryon collision cross sections to known values. i.e. how influential is the existence of Baryonic matter (in its observed form) to the overall structural form of the universe?

    It seems to me critical questions concerning the existence of Cold Dark Matter could go on and on and on?

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  2. Your experience at the conference reminds me of a Tibetan parable which says that when truth walked naked in the world folks did not want to look at it so it hid itself in a veil. It seems like scientists who devote their entire carreers seeking to unveil the truth cannot stand the sight of the naked truth when presented with empirical facts!

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  3. Stacy (something OT to this thread). somehow I cannot watch Alyson Brook’s talk I tried to find an email address of the web folks or the conference organisers, to pass it on to them. Could you let me know the names or contact info or any website where this can be found?
    Thanks

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  4. I watched the talk. I’ve watched a few videos of you giving talks and I’ve never seen you get so close to loosing your temper as you did in this. If I had been in your place I know I would have blown up at some point, so I admire your patience. Certainly you’ve been very patient with me over the years.
    My only comment about your talk itself is that I am sorry you didn’t get to present the whole thing. From what I could see I would have really liked to see the missing parts. Is your slide presentation available to down load somewhere?

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  5. I had to edit the talk heavily to give them something to go with the video (which was essentially impossible) so the original doesn’t really exist anymore. There isn’t anything there that doesn’t exist in some other form on my website. The only thing lacking is a coherent narrative, but well, that didn’t happen.

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