Hacker News: gmkiv

New comment by gmkiv in "Coulomb's law remains tricky to test at home"

gmkiv — Thu, 24 Sep 2026 17:33:10 +0000

Oh, he's so close! He's already constructed an electroscope. Now he just needs to use that to perform Cavendish's experiment, and he'll have verified Coulomb's law.

New comment by gmkiv in "Attention with Linear Biases (ALiBi)"

gmkiv — Sun, 14 May 2023 15:04:56 +0000

How does ALiBi compare to rotary positional embeddings? That method makes similar claims. I find ALiBi much easier to understand, but that’s probably not the best reason to chose it over other methods.

New comment by gmkiv in "The F-15 Eagle: Origins and Development, 1964-1972 [pdf]"

gmkiv — Sun, 26 Mar 2023 16:18:22 +0000

> I'm not sure if Burton was a Luddite who didn't believe in statistics or the scientific method, or if he didn't care about learning from his tests.

It's possible. It's also possible that he had a good sense of how test results are presented by program managers to Congress, and was trying to accurately convey the situation. Congress typically doesn't have time to delve into the details of the test, they get top-line results like "the Bradley did not catch fire when shot by an RPG" even though the footnotes would talk about the water in the tanks.

More generally, there is a tendency even today to make test results look good through judicious selection of test conditions. Program managers will refuse to do tests where "we already know the answer" - but only when we think the system won't work. We do plenty of tests when we have high confidence the system will work. So you get headlines like "86 of 105 hit-to-kill intercept attempts have been successful" [1], without the context that we never attempted the shots that we think we would miss, even if those scenarios are tactically important.

I'll grant that there are several motivations for testing like this, but let's not pretend that they are all purely technical.

[1] https://www.defense.gov/Portals/1/Interactive/2018/11-2019-M...

New comment by gmkiv in "US regulators will certify first small nuclear reactor design"

gmkiv — Sat, 30 Jul 2022 21:41:14 +0000

The link you provide seems to say that the cost of wholesale PV + storage is $85-$158 (bottom figure, line 3). Am I misreading that?

I’ve noticed that many solar+storage installations these days are 4-hour storage, so not sufficient for baseload. I think the number would be higher if we were shooting for baseload from our storage.

New comment by gmkiv in "We almost built 8 gigawatt-class floating nuclear power plants"

gmkiv — Sun, 22 May 2022 15:52:29 +0000

It's not obvious how to translate this figure into a standalone plant cost. The COB study is quoting the acquisition cost premium of a nuclear ship over a non-nuclear ship. I believe that estimate is the premium for taking a non-nuclear design and adding a nuclear reactor to it, so it does not include a lot of plant infrastructure that is part of the cost of civilian power stations. Also I would think the requirements for the containment structure and safety systems would be significantly different.

New comment by gmkiv in "Neighborhood Crime Data Doesn’t Belong on Real Estate Sites"

gmkiv — Fri, 17 Dec 2021 00:20:19 +0000

They don't want to exacerbate racial disparities, which is noble. They could have used that as their sole justification, but for some reason they also try to say that the crime datasets are inaccurate. Their reasoning for this is surprisingly weak. Regarding the National Crime Victimization Survey: "And there are troubling signs of this [racial bias]: in the 2019 survey, people reporting crimes were more likely to describe their offender as young, male, and Black than would be expected given the representation of those groups in the population."

New comment by gmkiv in "Leaked grant proposal details high-risk coronavirus research"

gmkiv — Fri, 24 Sep 2021 17:41:05 +0000

The value is to inform the larger discussion of the risks and benefits of gain of function research.

New comment by gmkiv in "Quantum astronomy could create telescopes hundreds of kilometers wide"

gmkiv — Wed, 21 Apr 2021 14:43:28 +0000

The state (phase) of the received photon will depend on the position of the receiver. Even if you have a perfect quantum hard drive, you still need to maintain the position of your receivers to within a wavelength. That will be hard to do if they are separated by a long distance.

New comment by gmkiv in "Quantum astronomy could create telescopes hundreds of kilometers wide"

gmkiv — Wed, 21 Apr 2021 03:28:04 +0000

I shudder to think of the difficulty in maintaining phase coherence at optical wavelengths for the baselines they mention in this article.

New comment by gmkiv in "Google told its scientists to ‘strike a positive tone’ in AI research"

gmkiv — Wed, 23 Dec 2020 17:03:59 +0000

The directive to strike a positive tone could be nefarious or benign; we can’t tell from the info in the article. Every research paper has a tone that depends on the personality of the author - I’ve seen it even in my dry field of quantum optics. Every result has many implications and how you discuss them, which implications you emphasize, and the language you use will affect the tone, even if you are not explicitly furthering an agenda. A given article could have a range of legitimate tones, depending on who wrote it. Asking a researcher to be on the positive end of the legitimate spectrum is benign. It can of course go to far.

New comment by gmkiv in "Gravity is unlikely to be the cause of quantum collapse, experiment suggests"

gmkiv — Mon, 07 Sep 2020 22:50:07 +0000

I happen to agree with you, the observer is a quantum system must get entangled with the quantum system, but that still doesn't explain probabilities. If you prepare a system - say sqrt(1/3) spin-down + sqrt(2/3) spin-up, and then observe it, repeatedly, your subjective experience is that you saw spin-down 1/3 of the time, and spin-up 2/3 of the time. I don't understand how purely unitary evolution can explain this. Does it?