G-HAT (Glimpsing Heat from Alien Technologies)

For those interested in the post about finding advanced civilizations in other galaxies by their heat emissions, Paul Gilster at Centauri Dreams has a write up about the study, including links to additional material as well as the actual paper.

I found that this part clarified the seeming contradiction in the Science Daily article.

The currently reported work tells us that none of the galaxies resolved by WISE in this study contain Type III civilizations that are reprocessing 85 percent or more of the starlight of their galaxy into the mid-infrared. And as mentioned above, out of 100,000 galaxies, only fifty show a mid-infrared signature that could be considered consistent with reprocessing more than 50 percent of the starlight.

These fifty point to the further investigations ahead.

The overall endeavor of which the study is a part appears to be named G-HAT (Glimpsing Heat from Alien Technologies).   Gilster links to a site that looks like it has lots of additional information on it, along with some interesting articles.

11 thoughts on “G-HAT (Glimpsing Heat from Alien Technologies)

  1. I am going to remain sceptical, especially in light of the Fast radio bursts (FRBs) being recently explained by the use of redundant Microwave ovens, that was a disappointment for me. I did take one thing from it, as Carl Sagan pointed out a culture even a few thousand years ahead of ours would seem godlike, given that they might be entirely different to us, even looking seems to be futile. Not that I want SETI to give up, I’d be thrilled to have alien life found even if it were microbial.

    I wonder at our ability to guess what they might be using technology wise, heat is a by-product would they be so primitive as to produce waste?


    1. I hadn’t heard that about the FRBs, although can’t say I’m too surprised. I didn’t even blog on that because it seemed like a long stretch.

      One nice thing about this effort is the scope of what they’re looking at. If there are Type III civilizations out there, the laws of physics, notably thermodynamics, say they should be detectable, at least somewhat.

      Unless of course the laws of physics as we understand them are incomplete, which is always possible. Until we learn that though, all we can do is search according to what we do know.


      1. “Unless of course the laws of physics as we understand them are incomplete, which is always possible.”

        More than possible — definite fact. The conflict between GR and QFT means that at least one of them is, at best, incomplete. (At worst, flat out wrong, but that seems unlikely at this point.)


        1. The problem, as I understand it, is that both GR and QFT have been extensively tested and confirmed. Whichever one of them is wrong (assuming it’s not both of them), it will be wrong similar to the way that Newtonian physics was wrong, in extreme conditions. In the cases of GR and QFT, extreme conditions might only be in black holes.


          1. The singularity of black holes is one place quantum physics breaks down, but it breaks down anytime you pass the Planck length (which is why it breaks down in BHs — the actual singularity is sub-Planck).

            According to QFT, space is filled with “quantum foam” — another “no idea” place-holder word like “dark energy” — due to uncertainty once lengths become sub-Planck. The more space is localized, the less certain you are about how much energy there is.

            (One thing making String Theory attractive is how it provides a natural minimum size and so does away with quantum foam issues.)

            The thing is, not working in only extremal conditions isn’t a pass for a theory that’s supposed to apply to all conditions. There’s nothing in QFT that allows an “out” as size decreases.

            And there are other issues with QFT — the need for super symmetry to explain certain things, for example. We kinda know QFT isn’t quite the answer. That’s why there’s so much work in ST and other approaches to quantum gravity.

            My personal wish is that quantum gravity fails. I’m fine with matter and energy being quantized. They clearly are quantized. But it’s not totally clear yet that space and time must be. All approaches are generally seeking to quantize space-time somehow. I’d like to see an approach that seeks to reconcile the two, and that might involve more changes to QFT than to GR.

            QFT is just too weird of a theory. GR is a sensible one. I want Einstein to win. 🙂


          2. Gravity does seem like a different beast from the other fundamental forces. People have been trying to cram it into the same mold, with carrier particles and the like. So far, it doesn’t seem willing to comply.

            QFT does seem like it has more room for additions, and with the LHC probing higher energy levels, it probably has a higher chance of getting them in the near future. But I fear the weirdness is here to stay. Too much of it is experimentally grounded. I suspect the reconciliation, when it comes, is going to take us to new levels of weird.


          3. Could be. I’d love to attend a physics conference with a tee-shirt that reads: There’s no such thing as a graviton! Might start some interesting conversations. I’ve spoken to other physicists who share the view.

            LHC has begun testing the upgrade. It’ll be a while before they’re running under full power. Hard to say what will turn up there, if anything. They’ll certainly explore the Higgs in more detail, but it’s possible the only other real news will be: Super Symmetry continues to not be found.

            The Higgs was pretty exciting, but it was confirmation of old physics. I want to see some new physics! There hasn’t been anything new since quarks.


          4. LOLS! I’m pretty sure those would be conversations hopelessly outside of my depth. Being physicists, I’m sure it would quickly get mathematical.

            I know a lot of physicists were actually hoping that the Higgs would not be found, since it would have shaken things up. It sounds like the LHC has found a few other particles here and there, but nothing seen as very significant, at least not yet. But even if they just bury SUSY, that’s at least a type of progress, ruling out whole classes of theories and, hopefully, focusing efforts in more promising directions.


          5. The annoying thing about a lot of modern physics is that it does require math to even talk about! In that domain, “theory” and “set of equations” are equivalent.

            As for SUSY, my understanding is that MSSM is all but ruled out at this point, but there are myriad other versions of supersymmetry that specify higher mass particles the LHC reasonably wouldn’t have been able to explore. Even with the upgrade, I don’t believe it will be able to resolve the matter definitively, although the lack of evidence to date is starting to look suggestive.

            It’s actually yet another bullet point on my “Nah… QFT can’t be right!” virtual PowerPoint presentation. 😀


          6. Max Tegmark in his book ‘Our Mathematical Universe’ described physical theories as a combination of mathematics and description, noting that physicists referred to the description part as “baggage”. In the mathematical universe hypothesis, the Theory of Everything would be a purely mathematical structure, with no baggage.

            From what I understand, the most likely versions of supersymmetry have been ruled out. There are still some less likely ones that the LHC might discover at its new energy levels. If those aren’t discovered, then the remaining theories would be ones that most physicists see as long shots, still possible but increasingly unlikely. If nothing is found, I get the impression that much of the theoretical physics community will conclude it’s time to go back to the drawing boards (or white boards, or whatever they use these days).

            It would be nice if the LHC came up with something big and utterly unexpected, that shook up the field.


          7. Yeah, although I’m not holding my breath.

            One hope is they might see “missing energy” in collision events that could be attributed to dark matter (rather than neutrinos).

            They’ll also try to determine exactly what kind of Higgs boson they’ve found — some versions of the SM allow more than one. (That’s why you often hear the verbiage that they found “a particle that seems to resemble the most common Higgs boson.”)

            Liked by 1 person

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