japanuspus

The surgeon who fixed my first knee injury advised me to do single legged squads if in any way possible: the balancing aspect is good for activating many small muscles around the knee, and the weight is high enough to maintain muscle mass even after age 50.

I think they are just being nice to people like myself who much prefer to skim a wall of text than sit through a video of someone talking.

You just pin the sub-dependency. This is builtin functionality for all the python environment managers.

The concept seems to be similar to the "Gridscale Storage"[0] system sold by Stiesdal technologies[0], which claims a round-trip efficiency of 55-60%.

The important insight here is that per Carnot's law[1], the higher the storage temperature the higher the theoretical max efficiency for thermal storage. Stiesdal had an initial concept that stored at even higher temperatures (1000C) and used a standard power plant steam turbine for converting back to electricity. But these turn-key solutions are probably more realistic.

If you are interested in realistic renewable energy, do browse the Stiesdal pages: Henrik Stiesdal [2] was pretty much the inventor of the modern wind turbine (sold the upwind 3-blade design to Vestas, CTO at Siemens Wind Power): He seems to have a superb intuition for industrializing heavy machinery. I am keenly following his advances into electrolysis and floating offshore wind power.

[0]: https://www.stiesdal.com/storage/the-gridscale-technology-ex... [1]: https://en.wikipedia.org/wiki/Carnot_cycle#Carnot's_theorem [2]: https://en.wikipedia.org/wiki/Henrik_Stiesdal

This is really nice - thanks for posting!

One reason Denmark has very affordable district heating is that it is based on "waste heat" from power plants, and "waste heat" is exempt of energy taxes (because those are paid on the primary energy sale, i.e. the electricity).

This comes with some perverse incentives in an age of renewables:

1. If the power plants use surplus electricity to provide district heating it is no longer a "waste product" and consequently taxed. Since the power plant cannot run without generating electricity, this leads to periods of negative power prices.

2. Cooling water from e.g. data centers is too cold for district heating, but it would be energy efficient to use heat pumps to extract that energy. This is not done, because the product would be subject to full energy taxes as it is not a waste product.

Yes, came here to plug Pijul as well: for distributed version control, the "first-class conflicts" of Pijul seems to be a step in the right direction.

For anyone who hasn't looked at Pijul, the theory part of the documentation [0] is well worth a read.

[0]: https://pijul.org/manual/theory.html

Cannot recognize this at all. In fact, Torx-screws are the only door-mounting[0] screws I have ever been able to screw out rather than cut.

[0]: Where I live (Denmark) doors and windows are these days mounted with an 8 mm hard steel screw directly into a slightly undersized hole in the brick wall ("montageskrue" in danish). These are by far the highest torque screws I have ever worked with. The early versions used Phillips rather than Torx, and nobody even bothers trying to get those loose before breaking out the saw.

My main complaint with the Windows implementation is that it does not not play well with the lock-by-default policy of the NTFS filesystem. I deactivated the the filesystem watcher on Windows after the agent repeatedly locking files so that checkouts would fail.

Just wanted to add some basic chemistry information as background

Hydrogen (H) can be split from water (H2O) with a by-product of Oxygen (O). Hydrogen is hard to handle logistically (as discussed elsewhere in the thread), and the real idea in "Power to X" is to include Hydrogen in another molecule with better logistics. Main contenders are Ethanol (C2H5OH, alcohol), Methane (CH4, ~natural gas), and Ammonia (NH3).

Ethanol and Methane are by far the nicest products: already used as energy carriers, easy to handle, relatively non-toxic, but they have one problem: They require Carbon (C) to manufacture in addition to Hydrogen. Even with increased atmospheric CO2 levels, CO2 concentration in the atmosphere is only on the order of 400 ppm and extraction is expensive.

Ammonia (NH3) is synthesized directly from Hydrogen and Nitrogen (N) which is makes up 70% of the atmosphere. The Haber-Bosch process used for this synthesis is a cornerpiece of industrial chemistry.

For anyone coming from the rust side and just looking for a cross-platform rust frontend framework: although not covered in any details by the docs, you can cut out all the web stuff and run everything from cargo.

I have a small `hello-world` example of a rust-only Tauri application at https://github.com/Japanuspus/tauri-from-rust

You do realize that most of the money for LHC end up in industry, not academia?

Thanks for sharing - have stumbled over the term "geometric algebra" a couple of times, but this article made it click for me.

I completely agree with the sentiment that the algebraic mumbo jumbo often used to introduce quaternions is not very satisfying. Fortunately, as quantum computing becomes a mainstream topic, more people will have to learn about "Rotations on the Bloch sphere" [0] -- and then quaternions and rotations actually make sense.

[0] https://en.wikipedia.org/wiki/Bloch_sphere#Rotations_about_a...

For context: Apple provides Rosetta for Linux to allow native x86 binaries to run inside Linux guests on Apple silicon hosts as discussed yesterday [0]. This article explores what other uses can be had for Rosetta on Linux.

[0]: https://news.ycombinator.com/item?id=31644990

As a low-energy quantum physicist, I completely agree: Experimental high-energy physics has become primarily an industrial subsidy scheme[1], and if we want the highest chance of reaching a grand unified theory, it seems the money would be much better spent elsewhere (cosmology, space-based observatories, research positions for young physicists without publish-or-perish incentives to run for the latest fad).

The short history of physics in TFA is spot on: Einstein and the quantum pioneers added abstractions to build physical theories with prediction power, whereas current high-energy physics theory seems to be mostly a mathematical exercise. This has been confirmed by numerous insiders, including by Hossenfelder as mentioned in the article, and Lee Smolin ("The trouble with physics") who is also a theoretical physicist.

Things have changed a lot since accelerators became a must-have for high-energy physics: Today we have detectors and computing power that let us observe the natural experiment of the universe with a precision and diligence that would be impossible when LHC was commissioned. I find it much more likely that we would learn new physics by giving 10-year grants to 1000 young physicist of revolutionary spirit, and let them use the tools they could build themselves, than by handing that money to the old guard which has produced nothing of significance for the last two generations.

[1]: The industrial subsidy angle is not touched upon in TFA, but it is clear that there is a large number of people and companies making a good living from mega-physics, and talking to colleagues in the field, I get the distinct impression that it is not always they physicist walking in the front when asking for more machines.

For anyone looking in this direction, Obsidian[0] with the excalidraw-plugin[1] is an awesome solution: Free for personal use and cross-platform.

[0]: https://obsidian.md/ [1]: https://github.com/zsviczian/obsidian-excalidraw-plugin

But the second version needs to run `.strip` twice. It might not make much of a difference for `strip` -- but it still hurts my eyes, and could be an actual performance issue for other operations.

Your wording seems to imply that the US system has a working parliament, which has clearly not been the case for the last couple of election cycles?

Did you have a look at the source for the page?

This is a real, self-contained HTML page as intended by the old ones.

Methanol and ethanol share the same fundamental problem: they are both carbon-based, and despite global warming atmospheric CO2 is still well below 0.05% of the atmosphere which means it is very resource-consuming to extract it. As long as we still use some fossil fuels, you can capture at power plants, but in the long run it is a dead end.

Ammonia, on the other hand, just requires nitrogen which is 70% of the atmosphere and very easy to extract in industrial quantities.

The submitter likely stumbled over the site after reading the discussion on `oggify` earlier today, https://news.ycombinator.com/item?id=31080518 (I know I did).

I am not sure there is a universal value for "what people think" about pumped hydro energy density, but your numbers are quite far of: 3TWh at 1000m pump height would require 3e6Wh3600s/h/(1000m1000kg/m3*9.8m/s2) = 1.1e6m3, so a waist-high lake of one square kilometer would do.

For what it is worth, in Europe, Switzerland is doing a lot of pumped hydro powered by surplus French nuclear power in the summer time. Norway has huge amounts of hydro and only pumps a little, but it doesn't matter much: The Scandinavian grid is so well connected, that hydro will ramp down when power is available elsewhere, in effect providing on-demand provider for the whole region.

Second this, the article in Science is well worth a read: has an excellent overview of the issue and a clear technical discussion.

I am puzzled by the choice of derailleur gears over intra-hub gears.

The motivation must have been that it allows the integrated rims and hubs, which are probably much easier to manufacture than spoked wheels at this size. The downsides seem significant though: A derailleur with gears this small is going to wear very quickly, and when it is time to replace it, you just have to hope that Kwiggle is still around to supply you with spares.

I have been a bike-fiddler since my teenage years, but it was only recently (40+) I tried taking apart an intra-hub gear. To my surprise, the whole gear mechanism is fitted to the axle an can be replaced in one go [0]. The only functional parts of the hub/housing is half-bearings and ratchets. The cool approach for Kwiggle would be to replicate these and just pop in a Shimano gear.

[0]: https://si.shimano.com/pdfs/sm/SM-IHG-INTER7_ENG.pdf page 43 ff.

This. It might be true that nobody _in academia_ remembers a good TA, but I would claim that the TA-student relationship is one of the best ways to create a network across classes at uni. Personally I have used connections to former TA's and students in industry on multiple occasions.

As a former quantum physicist who has just decided to go back into quantum computing, this was my take as well: Introductory quantum physics courses may still include wave-function collapse and all that nonsense, but I have not met many physicists who use this as a mental model.

To be a bit more specific as to how _decoherence_ solves this, one way to see it is that classicality (i.e. observables having specific values) is an emergent property in the limit of near-infinite degrees of freedom in the same way that e.g. thermodynamic properties (temperature etc.) are emergent properties of classical systems in the limit of near-infinite degrees of freedom.

Putting it on the edge, claiming that quantum theory is at a dead end is like claiming statistical physics is at a dead end.

One of my personal favorites for how to formalize this is the work on "pointer states" by Wojciech H. Zurek. There is a freely available Physics Today articls [0], and you can find surveys of further work e.g. in the introduction of [1].

[0]: https://arxiv.org/abs/quant-ph/0306072 Zurek, Decoherence and the transition from quantum to classical -- REVISITED [1]: https://arxiv.org/abs/1508.04101 Brasil, Understanding the Pointer States

This seems to be a good review of "classical" quantum algorithms, i.e. based on the circuit model and assuming ideal quantum hardware, but I think it misses the key thing that is happening in quantum computing right now.

At least to me, a former quantum computing researcher who has just switched back to quantum computing after a decade in traditional computing, the thing that made me decide that now is the time to move is that there is an emergence of new algorithms focusing on making the most of the noisy intermediate scale quantum (NISQ) computers that we can actually build today.

One of the prominent examples is the variational quantum eigensolver (VQE) algorithms [0, 1] which are hybrid quantum-classical algorithms which can often serve as replacements for the phase estimation algorithms described in the final section of TFA.

[0]: https://www.nature.com/articles/ncomms5213.pdf [1]: https://iopscience.iop.org/article/10.1088/1367-2630/18/2/02...

Same in Europe, at least in Denmark. Source: my dad is a civil engineer who has been doing renewables since the oil crisis in the 1970’es.

No, for Lego the injection molding is strictly headquarter business. To the extend that the old molds/tools are literally encased in concrete beneath the buildings (you can see examples if you go to "Lego House" museum at the headquarters in Billund, Denmark).

Re. everything is Windows in Denmark, my understanding (backed by a few acquaintances as MS) is that Denmark is being actively pursued as a test-marked by Microsoft: It is a sufficiently advanced market that they can get everything tested, and sufficiently small that they can sell at loss without large expenses.

My experience working in a large Danish Corp. is that you need a really good reason before you can get a non-Windows machine, and if you do you still need a Windows machine on the side. Still, coming from a decade of OS X and GNU/Linux, Windows was actually surprisingly workable as a development environment.