The State of the Universe Slides

So I have given my talk on the State of the Universe. It’s a bit intimidating giving a talk with Nobel Laureates in the audience, but I think it went OK.

The slides are here:

I’ll add a link to the recording when I have it. Here is a link to the event. The video is very long because of a lengthy introduction and discussion at the end so if I get time I’ll put an edited version of just the talk on my Youtube channel.

In the meantime here’s a picture of me looking weird during the presentation:

15 Responses to “The State of the Universe Slides”

  1. There was some discussion regarding Hubble-constant tension, with Peter pointing out that it is not just local vs. distant measurements, but also luminosity-distance vs. angular-size—distance measurements. Another distinguishing characteristic is the angular scale involved (supernovae are small, CMB fluctuations are large).

    Nick Kaiser mentioned grey dust. Note, however, that something which makes the local supernovae fainter (without being corrected for) would make the measured value come out too low, whereas it is high with respect to the CMB measurement. (The same goes for some selection effect which observes objects preferentially where there is less matter in the beam.) To be sure, he mentioned that in the context of possible mechanisms which could violate the Etherington reciprocity relation; how that could be related to the Hubble-constant tension is unclear (at least to me).

    Could the opposite be happening? Supernovae are preferentially observed where there is more matter in the beam, making them brighter? That would go in the right direction. But for that to be a selection effect, one would need a rather steep luminosity function, so I don’t think that that idea would work.

    My guess is that there is some systematic error and/or that the uncertainties are underestimated.

    Trivia question: assuming random errors, what is the probability that the true value is bracketed by the high and low measurements?

  2. I remember another debate about the Hubble constant, a quarter of a century ago. Paul Schechter called out from the audience “What’s the problem? They agree at three sigma!”

  3. In the old days, I doubt that anyone would have predicted that we would know λ and Ω to better precision than H.

  4. Richard Says:

    slideshare.com is a dumpster fire of trackers and cookies and Javascript and heinous junk. Of course it’s “free”.

    Just put a PDF (or raw Beamer, whatever) file up on your academic hosts’ web site. Nobody needs the middlemen.

  5. Congrats! Excellent presentation. The few key points which I took away are as follow.
    One, there is no breakthrough for the cosmology, not even in the horizon.
    Two, all the current theories are all incomplete; that is, a new paradigm shift is needed.
    Three, the “Hubble-constant tension” could be the opportunity for some new advancements.

    While you have mentioned the failure of SUSY and its impact on the cosmology, you did not address a very important issue in the HEP (a major paradigm shift is going on).
    The M-string theory paradigm is now dead (with the following evidence)
    First, the anti-M-string physicists have grown from a few (Sheldon Glashow, Roger Penrose …) to a lot (including Lee Smolin, Peter Woit, Sabine Hossenfelder, …).
    Second, the major proponents of M-string (such as Edward Witten, …) have stopped spending any more time on it.

    This major paradigm shift in the HEP has a very important impact on cosmology. I am very sure that you know about this but reluctant to mention it for a sociological reason.

    Then, about the “Hubble-constant tension”, I will make one suggestion here.
    Instead of looking for any new ‘particle’, it could be explained with a ‘dark flow (the melting of dark matter into the dark energy)’.
    Of course, this is not just a suggestion, it can be calculated in the ‘of calculation of the Planck CMB data via a derivation equation’.
    A recent comment from Peter Woit: {If a highly complex and obscure set of ideas accurately computes the details of something you can observe, you know there is something right about it, even if you don’t understand the set of ideas. See https://www.math.columbia.edu/~woit/wordpress/?p=12353#comment-238968 } provides some credibility of the above statement.

    • It might very well be the case that sting theory is on its way out, and I tend to agree. However, that is not decided based on the proclamations of various internet pundits.

      How do you expect such a paradigm shift in HEP to affect cosmology?

      Do you have any concrete predictions from the dark flow?

      • {However, that is not decided based on the proclamations of various internet pundits.} Agree 100%.
        The death of the M-string is based on the following facts.
        One, its vital part (the SUSY) is not there.
        Two, all its predictions (if any) are not panning out.
        Three, it is totally useless to derive the cornerstones of this universe (the nature constants, CC, Alpha, Planck CMB data, etc. while they can be derived in a new paradigm).
        Four, except a few diehard devotees (such as John Schwarz, …), most of the M-string founders are, now, not working on it.

        {Do you have any concrete predictions from the dark flow?}
        Yes, it is about 9%, the number is almost the same as the “Hubble-constant tension”, see the graph in this tweet https://twitter.com/Tienzen/status/1402739317504495618

      • {How do you expect such a paradigm shift in HEP to affect cosmology?}
        The M-string paradigm is out, and a new one is coming in.

        The new epistemology for the correctness of a theory is outlined by Peter Woit’s saying: {If a highly complex and obscure set of ideas accurately computes the details of something you can observe, you know there is something right about it,…}
        That is, this new paradigm must provide the derivated equations to calculate all (not one or two) cornerstones of nature constants (such as CC, Alpha, Planck CMB data, Higgs boson mass, etc.).

        When CC and Planck CMB data can be derived via some equations, the cosmology will be in a different state.

  6. Shantanu Says:

    Peter: you did not mention the Lithum 7 problem in Big-bang nucleosynthesis? Also about RAR and Baryonic Tully fisher relation?

  7. […] the end of my talk on Wednesday Floyd Stecker asked me about what the James Webb Space Telescope (due for launch later this year) […]

  8. […] A video of the full event can be found here (1.6GB) and a PDF file of the slides can be found here. The slides are also available to be viewed here. […]

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: