Hacker News Reader

theothermknon Göttingen researchers identify existing drug with potential to treat Covid-19

Some in here have been asking about risks and side effects. A quick google search turned up:

https://www.practo.com/medicine-info/camostat-2499-api

I'm just a layperson, but this looks like a run-of-the-mill prescription drug. Hope this helps to allay some concerns and keep the signal-to-noise ratio higher.

theothermknon Freeman Dyson Has Died

One thing that's slightly interesting about Dyson Sphere's is that spherical shells of matter exert exactly no gravitational pull at any point in their interiors. That is, the integral of gravitational pull over the whole shell is identically 0 for every point inside the shell.* This goes for any force that falls off by the inverse square rule, e.g. the electrostatic force.

In short, there's no practical way to stick an atmosphere, much less a civilization composed of life forms that depend on gravity, to the inside of the sphere, even if the other engineering challenges could be overcome.

* One thing that's suddenly more interesting to me now is if the space at any point is being "pulled" equally in all directions, resulting in zero force, or if the bends in space-time cancel out. In the limit, for example, could you "tear" space-time inside a dense enough and/or heavy enough shell of matter?

theothermknon The Race to Build the First Sustainable Supersonic Jet

It's clearly a submarine (http://www.paulgraham.com/submarine.html) article. The article is so light, and so full of hot air, that it practically advocates for balloon travel, not supersonic flight.

theothermknon People no longer believe working hard will lead to a better life, survey shows

Pithy, perhaps, but not entirely justified. For example, the implied causation might actually be reversed, that people who naturally trust institutions consume more news. The causal relationship could also be external to both: some other factor, like financial stability, causes people to believe in institutions and to consume more news. Or, the cause could even be direct, but much less cynical: The news may accurately inspire justified confidence in institutions. (Conversely, people who prefer to make up justifications or excuses might blame institutions and prefer to not expose themselves to news that discomforts that worldview.)

theothermknon What to do if you’re stopped by the police

James Duane recently updated his advice, incorrectly restated in the article and in many places in this thread, in a book entitled You Have the Right to Remain Innocent. There is a long and short of it, but I'd rather see you buy the book, so I'll just mention a few things. First, "I'd like to see a lawyer," is not nearly succinct nor strong enough, as per recent case law and Supreme Court rulings. Second, the Supreme Court has ruled that invoking the 5th Amendment can be admitted as evidence of guilt, especially if you say it wrong, as is simply remaining silent. Finally, the people in here saying to, for example, just assent to a search in order to be on their ways are hopelessly naive about the frequency of evidence planting, the potential to be misheard, misremembered, or deliberately misquoted by cops looking to get a tidy resolution to whatever messy situation confronts them. Not all of them, but enough of them and often enough that I cringe at most of the advice in this thread, much of which you (Yes, you!) personally think is great.

Buy the book. It's cheap, and an engaging quick read. Good luck to you all!

theothermknon Electric Cars Threaten the Heart of Germany’s Economy

> "Once fusion is cracked" is almost on par with "once perpetual motion machines are cracked." It presupposes that fusion being "cracked" is a reasonable thing to expect.

Oof. One need only to peruse your comment history to see where this sentiment is coming from, but even that is no excuse for that obtuse argument.

"Perpetual motion," on the one hand, is quackery outlawed by straightforward thermodynamics, breaking the rules of which allows assertions like "chair seats and door handles should be spontaneously heating up to incandescence essentially at random." Fusion, on the other hand, is a technical problem.

Fusion researchers at MIT, ITER, and other institutions at the top tiers of academia across the globe are not a cabal of greedy grant-dependent charlatans bamboozling their way through careers in bad faith, deliberately ignoring the lone rational voice of Lidsky and his Johnny-Come-Lately-The-Baptist on HN, u/pfdietz. It's perfectly rational (Sane, even!) to cast aside internet naysayers (no matter how zealous) in favor of deferring to, you know, actual experts.

theothermknon Blue light may not be as disruptive to sleep patterns as thought: mouse study

https://www.health.harvard.edu/blog/will-blue-light-from-ele...

This is widely debunked. The above is but one of many such counterpoints.

theothermknon Using Binary Space Partitioning in Doom

> That story about Carmack applying cutting-edge academic research to video games has always impressed me.... He deserves to be known as the archetypal genius video game programmer for all sorts of reasons, but this episode with the academic papers and the binary space partitioning is the justification I think of first.

I'm not throwing shade on Carmack when I say that the reason the author states seems to me to be evidence, taken alone, of the exact opposite of the case that Carmack is "the archetypal genius video game programmer." Or, if it is, then it impugns the profession of video game programming, because, in most real engineering fields, a literature review is the first step, not the desperate measure taken after "creativity" has been exhausted. It seems to me that a better case can immediately be made that the originators of the technique are the real geniuses, having come up with the idea, and Carmack just adopted it. Geniuses create; the rest of us adopt, right?

Again, don't get me wrong: Carmack could program circles around me. (Or ellipses, or pentagons, or particle clouds, or fractals, or...) But affirming the consequent doesn't make him "a genius." He may or may not be, for other reasons, but 'applying a known technique' just can't be one of them.

theothermknon Let’s Talk about Ghastly Dishwashers

A thought on the political, rather than technical, side of the story:

I went through a regrettable phase of reading about military strategy and the like, and one of the things that stuck was how good strategies need to have a component of randomness to them, to make them unpredictable by the enemy. Trump is chaos and randomness, and him having landed on this issue, and in such a random (?) and (apparently?) sexist way is both testament to that, and an indicator of the danger he poses to Democrats and what passes for the left in the US: They've left themselves exposed on many fronts because they've faced a very ordered and predictable foe until Trump. Nobody, but nobody, on the right would have launched an attack on the left with "women have told me dishwashers suck, now," before Trump, so they were free to pass stricter and stricter regulations, unpunished by the cost to consumer satisfaction.

I am loath to admit it, but there is something to be admired, here, some kind of low genius that demands respect, under threat of great peril if respect is not afforded.

theothermknon Proprioception: The Silent “Sixth” Sense

I made a minor personal discovery recently along these lines and would love to hear from others here if they can reproduce it: I can "see" my hands with my eyes closed. That is, if I hold my hands out in front of my face with my eyes closed, I can see a faint image of them in the eigengrau. Further, if I then move my hands outside of my normal field of vision, (say, to my side) the image persists; I can "see" them outside my normal field of vision. While this effect is strongest for my hands, it does extend somewhat to my legs and feet if I pay extra attention.

I'm curious if others can reproduce this for themselves?

My hypothesis is that the visual areas of the brain can get involved when the eyes are closed, and can pick up and interpret the proprioceptive information spatially. It may be that it's always happening, but that the "image" of one's hands is swamped by visual data when the eyes are open. Another hypothesis, I suppose, is that the visual expectation of the hands may be registering or, rather, its absence. You're "seeing" the expectation of the hands that should be there, but are blocked by your eyelids.

I should say that the sensation of seeing the hands is pretty fine, extending to the motions of the fingers. That said, it's easy enough to lose the image or forget it is there.

theothermknon Longevity Linked to Proteins That Calm Overexcited Neurons

> Does the low neural activity correlate with a less active experience of the world?

From the fine article:

> "Neuronal overactivity may not feel like anything in particular from the viewpoint of the worm, mouse or human, unless it gets bad enough to provoke seizures. But perhaps over time it may damage neurons."

No.

theothermknon Domes are overrated

The actual fuel cost to put things into orbit is quite small, on the order of $30/lb of payload. I've done this analysis on HN before, but the gist is that LOX and kerosene are about the cost of milk, and roughly as dense on average, and you need about 20-30 lbs of propellant for each lb of payload. The rest of the cost comes from labor and amortizing the launch vehicle and infrastructure. The cost floor is <stick wet finger in breeze> probably around $100 (2019 dollars) or so per pound. Not great, but not "extraordinarily expensive." This is without going to gun-assisted schemes for durable raw materials and the like. (Incidentally, this seems insane to me. It seems like you want rockets for people and fragile goods, and guns for anything that can take a few hundred to a few thousand gees or more, like steel or aluminum or water (ice) or.... But, this is just a SWAG. There could be hiccups there preventing a gun-assist cost floor much lower than that for rockets.)

theothermknon Why does F = ma?

'F = ma' is a special case of 'F = d/dt(mv)'. Expanding the latter via the product rule, we get: F = m dv/dt + v dm/dt, where a=dv/dt and dm/dt is the time rate of change of the mass of the object. This fuller form matters in, for example, aerospace engineering, where the mass of the rocket is changing as fuel is burned, so dm/dt is emphatically not 0.

I wonder if the philosophical questions asked in the fine article could have been addressed more satisfyingly from that more general starting point?

theothermknon The impact of direct air carbon capture on climate change

I think that you're thinking of the cost of turning the CO2 (and water) back into fuel, which can be argued along thermodynamic and irreversibility lines to show that unscrambling that egg always requires more energy than obtained from combusting. However, I don't think there is a similar thermodynamic argument on the energy costs of mere capture. It's not a priori impossible that a fractional distillation column with a clever configuration of heat exchangers, for example, could capture all the carbon released by the fossil-fueled plant that powered the column in the first place (and more).

Arguing that mere capture would require more energy than is released would be akin to arguing that cleaning the fireplace would require more energy than was released by the fire, on the mistaken grounds that ash removal took as much energy as regrowing the wood that was burned. Both the ash and the CO2 are in a lower energy state, so there's thermodynamic room to maneuver.

theothermknon Cable to the Stars – The Skyhook [video]

I think what bothers me most about this kind of paid fluff is that it fools the viewer into thinking they've learned something worthwhile, when they've only seen something pleasant. Another poster linked to a brief Wikipedia article, and even it mentioned that the technology is nowhere near ready, citing erosion by atomic oxygen as one concern.

What we have here is a glossed-up version of the simple observations that spinning things spin, and "rolling" things move faster at the top than at the bottom. The rest has been left as an exercise for the reader's active and uninformed imagination. Don't fall for it.

FWIW, my guess is that exactly 0 tethers as described in the video will ever play an important role in getting humans into space, for various reasons of various veracity. But it's all guesswork, which is all any of us have. Oh, and sign up for Brilliant.com.

theothermknon Nuclear fusion is 'a question of when, not if'

The limiting factor for ITER was the strength of magnetic fields that could be attained from the superconductors available at the time. The promise for ARC/SPARC at MIT is that the field strengths available have recently doubled, and performance goes something like the 4th power of field strength, so a smaller reactor can reach the conditions that only a larger one could have reached when ITER was designed.

These smaller reactors should be cheaper and faster to build.

theothermknon The Career of Mountaineer Fred Beckey

I saw him once in the early 2010s in Vertical World's Redmond location, but I didn't realize it at the time. Just some old guy in a harness feeling the holds in the bouldering area. We kept to ourselves.

Later, one of the employees told a story about how he met Beckey at the counter one time. Beckey had asked if he could climb, and the employee told him the rate for a day pass, not realizing who it was.

"I'm Fred," Beckey volunteered in frustrated amazement.

"Fred who?"

"Fred Beckey."

He waved him in to climb for free, of course.

theothermknon Are Aerospike Engines Better Than Traditional Rocket Engines?

What I'm saying is that the video contains numerous misconceptions, errors, and dubious bits of hand-waving. I'm not saying that people think they're engineers after watching. I'm saying that he is not trained as one, and that it shows in his work. I'm also saying that "what this guy is doing" and "why it's so valuable" are both undermined by his lack of training.

Long ago, some cranky academic wrote on his very well-sourced and specialized website, back when there was still that sort of thing, something like, "Everybody said that the internet was going to let anybody say anything at all. It turns out they were right."

I'm fine with the backlash from what you call my "gatekeeping." (I imagine that some gates need to be kept, but I suppose that's another story.) My point is that "the best on YouTube" is not as grand a qualification as one might suspect, and is certainly not a guarantee of accuracy.

theothermknon Are Aerospike Engines Better Than Traditional Rocket Engines?

The issue is that an aerospike engine is a spike engine that has been truncated, with the truncated portion replaced with an aerodynamic "spike," which also eliminates base drag.

theothermknon Are Aerospike Engines Better Than Traditional Rocket Engines?

> ... given that he has doesn't have any kind of formal training in it.

As someone who does have some training in it, I can say that "best space content on YouTube" is akin to "best brain surgeon in a room full of circus clowns."

He gets a lot of stuff right, don't get me wrong. But the appearance of credibility is down to enthusiasm, specialty of focus, and editing and delivery. It's fine as far as it goes, but it's infotainment. It's more important that you be entertained and feel smart than sit down and struggle with the actual application of engineering principles and achieve any kind of reliable knowledge.

theothermknon Are Aerospike Engines Better Than Traditional Rocket Engines?

It is a pet peeve of mine that people call all spike engines "aerospikes." An aerospike engine has a truncated physical spike that is replaced with expanding gasses. In other words, it has an aerodynamic spike, or aerospike. Spike engines that taper to a line (for linear engines) or a point (for cylindrical engines), are just "spike engines."

I know I've lost this one among popular and lay audiences. It's just way too cool to say 'aerospike.'

theothermknon A Lunar Space Elevator Is Feasible and Inexpensive, Scientists Find

> [T]his proposal lacks the most compelling reason for building a space elevator: breaking the bonds of Earth's gravity well.

This proposal actually addresses exactly that problem. The dangly end of this thing down around GSO will not actually be in orbit at GSO. Rather, it will be hanging, stationary, at that point. In other words, you don't need to get 'into geostationary orbit.' Rather, you just need to lob yourself up so that your apoapsis is as high as GSO. Once there, you hook onto the little eye loop, or whatever fancier attachment system they devise, and wait to be pulled up to the Moon, more or less.

The key thing here is that you don't have to expend all the delta-v to get into GSO, but rather just enough to lob you to height. This, in itself, is a tremendous savings, given that you're shaving velocity off of a very large delta-v, where the penalties from the rocket equation are most severe. However, even if you only got a free ride from actual GSO to the Moon, it would still be an important savings.

theothermknon Tokamak Energy exceeds target of 20 Tesla with HTS Magnets

There's also a video that covers it in a bit more detail: https://www.youtube.com/watch?v=43Tl39CYhNM

theothermknon Templates for Cutting Gears from Wood

A lot of people believe this, but it is incorrect. In plywood, the glue transfers the load across the faces of each ply from strand to neighboring strand through the adjacent plies. This can result in a stronger bond between neighboring strands than if no cross-plies were present. This amounts to more than just splitting resistance.

As a parallel case, consider multi-ply composite construction, where sheets of fabric, sometimes of sheets with a single fiber orientation, are laid at angles to each other to spread the loads in exactly this way. They both better approximate an isotropic material, and are stronger than an equivalent thickness of singly-oriented plies all in the same orientation.

theothermknon The Spaceline: a space elevator alternative achievable with current technology

This is a straightforward calculation, with modest bookkeeping requirements, that is possible with undergraduate physics and calculus. As a sci-fi author, your craft will be improved by forcing yourself to do it. You'll be concerned with centripetal acceleration, yield stress, density, pressure, free body diagrams of pressure vessels, summation of forces on a differential element, and fairly basic integration (after taking symmetry into account).

theothermknon 42 is found to be the sum of three cubes

Just googling "42 sum of 3 cubes" would have yielded better answers with less fuss. In general, I always google before asking in a forum. It's like not littering.

https://www.google.com/search?client=ubuntu&channel=fs&q=42+...

theothermknon In a small trial, drugs seemed to rejuvenate the body’s ‘epigenetic clock’

Aubrey de Grey has said numerous times that he suspects that if we were able to repair mithochondrial DNA, that has about a 10% chance of being all or most of the anti-aging puzzle, in his estimation. IIRC, he admits this is speculation. Still, he's no slouch in this layperson's book, so his statement gives me the warm fuzzies.

theothermknon Inequality driving 'deaths of despair'

The summary line of the article:

> Widening inequalities in pay, health and opportunities in the UK are undermining trust in democracy, says an Institute for Fiscal Studies report.

It's addressed again, later in the article:

> Sir Angus said "people getting rich is a good thing" but not if it meant "enriching the few at the expense of the many".

In the U.S., we talk of the American Dream, but the more modest versions of it weren't really a dream, but more of a promise, or an agreement: You could get by, and even modestly prosper, by being a person of good will with a dose of diligence and hard work; life could be fair. I think that got lost in the inevitable exaggeration of that dream for dramatic effect, things along the lines of forming the next Google in your garage or of winning the lottery or getting promoted into the C-Suite for your ingenuity or "moxie" or whatever. Granted, this hasn't been a credible belief for all sectors of society (It helped to have had white skin.), but it enjoyed some prevalence. To the extent that it was believed, it animated people's actions. They could bear up under a dreary job to send their kids to college, or to save up for retirement, or both. Devastations like cancer or some other personal disaster could be regarded as exceptions, enough so to hold the Dream together.

It just isn't like that anymore. Predatory insurance companies seem bolder in their greed. Hospitals seem complicit. The easy money available from being the only manufacturer of (honestly pretty shitty) cars went away, and labor prices deflated out from under the working classes. Houses, formerly built to last a lifetime, are built to sell, and then fall apart. The whole thing has turned to ashes.

Honestly, the honest, modest version of the American Dream is gone. Hard work is rewarded with insecurity and layoffs. The ACA even seems tenuous under Republican rule, and that only for the slight majority that think the ACA to be progress over private victimization. All that seems left is the prospect of walking over one's peers to a better life. We may malign CEOs as having said, "Fuck you, I've got mine," but we feel left with, "I'm sorry, I have to get mine."

The point of this ramble is not to diminish the contribution of naked inequality of the scale we're seeing. (I think, practically speaking, that's the cause.) Rather, the point of this ramble is that it's something like the modest American Dream that has to be tenable in order for a stable working class, and therefore democracy, to limp along much longer. Where there is no vision, the people perish.

theothermknon Alternate Day Fasting Improves Physiological and Molecular Markers of Aging [pdf]

This change was reported over 4 weeks, or 28 days.

For a 180lb person consuming, on average, 1900 kCal/day, a 37% drop in calories is a 703 kCal/day deficit below their initial equilibrium. This is 19,700 kCal over four weeks. Divided by 3600 kCal/lb, this is about 5.5 lbs. 4.5% of 180 lbs is 8.2 lbs. So, we're in the ball park. A 3-lb deficit from reduced inflammation (water) seems reasonable.

For a higher initial weight, you can get the numbers to agree exactly. I'm 6' and 182 lbs., which is just barely overweight. In the U.S., were I live, I look pretty "fit" by comparison with the average person. (I'm not, but that's another story.) According to [1], Austria, from where the participants were likely sourced, is only slightly leaner than the United States.

Therefore, their numbers seem to line up. Westerners are stuffing themselves.

[1] https://www.indexmundi.com/blog/wp-content/uploads/2013/04/w...

theothermknon The Trouble with Fusion (1983) [pdf]

I'm a layperson like everyone else here, so I'm just going to rely on the fact that fusion research is ongoing, well-supported by government and private sector investment, and is an active area of research for hundreds or thousands of intelligent and sane institutionally supported academics, as reasonable and practical justifications for my belief that fusion is not quite as problematic as laid out in Lidsky's dated and superseded work.

However, for a sketch of how to address the talking points of the more strident objectors one encounters in the wild, one can perhaps turn to https://fire.pppl.gov/fusion_critic_response_stacey.pdf for some ideas. Cheers!