Hacker News: kj4211cash

New comment by kj4211cash in "Air Purifiers as White Noise Machines"

kj4211cash — Sat, 24 Oct 2026 01:17:35 +0000

We have higher numbers than those and live fairly far from any freeway. Maybe your high-rise is doing better than you think.

New comment by kj4211cash in "Incentives in Academic Research"

kj4211cash — Tue, 06 Oct 2026 12:49:00 +0000

FWIW, I thought that initial quote was very relevant but was also glad you didn't waste a paragraph explaining what everyone knows, that over-emphasizing publication and citation counts and grant money raised is killing academic research. I don't have good ideas either. In the age of AI, cheap metrics and metric hacking are only going to become more prominent.

New comment by kj4211cash in "Ask HN: What are you reading to your kids?"

kj4211cash — Thu, 01 Oct 2026 12:15:17 +0000

Just realizing the irony of me complaining about Narnia and recommending PJ Library in the same comment section. Yea, Narnia is probably fine.

New comment by kj4211cash in "Ask HN: What are you reading to your kids?"

kj4211cash — Thu, 01 Oct 2026 12:12:36 +0000

Just wanted to give a shout out to PJ Library for anyone (willing to claim that they are) Jewish. There is a free service where they send a free book a month. I'm ethnically Jewish but not religious at all. Don't support the current Isreali regime at all. Etc. And I love the books. They are not religious books. My kids favorite one is about a penguin and an elephant and going to grandma's house for dinner.

New comment by kj4211cash in "Ask HN: What are you reading to your kids?"

kj4211cash — Thu, 01 Oct 2026 12:06:15 +0000

I'm in the same boat with 2-year-olds. It's been years but Narnia is very Christian / bible coded right? I guess it's fine to read to a little one, but I'd be kind of hoping that doesn't become their favorite book series. Or am I overreacting? I'm not letting my kids near Ayn Rand when they are older :p. Phantom Toolbooth would be great.

New comment by kj4211cash in "US halts flights at busy East Coast airports, says fiber line cut"

kj4211cash — Tue, 22 Sep 2026 01:53:10 +0000

That system wouldn't have replaced the one that went down. It's good to see investment in this area but that system is not going to fix much TBH.

New comment by kj4211cash in "The Beauty of Roundabouts"

kj4211cash — Wed, 16 Sep 2026 03:56:06 +0000

It's so funny seeing most of the comments, plus the original article, implying that roundabouts are always better or always worse than traffic signals. As someone who used to be a Transportation Engineering professor, they have a time and place where they outperform traffic signals but it's definitely not everywhere. It is known and there are many traffic simulation software tools that will give you a pretty good indication of what will happen if you put a roundabout here or a traffic signal there.

This thread reminds me of when my libertarian friend was explaining to me how traffic shows how everything can work well when everyone acts in their own self interest. Well, sure, except for all the traffic laws, the difference between User and System Optimal that traffic engineers spend much of their lives trying to bridge, and, you know, the fact that it took an enormous effort by government to build smooth roads and put up signs everywhere. Sigh. I'm not saying Transportation Engineering is the most important, innovative field, but funny things happen when not transportation engineers talk about transportation systems.

New comment by kj4211cash in "Giving up on smart rings"

kj4211cash — Tue, 15 Sep 2026 22:36:17 +0000

I just switched from a Whoop to the Fitbit Air. Whoop wanted $350 for a subscription fee which I just found really ridiculous. It's only been a few days, but the Fitbit Air might even be better at tracking sleep. And it looks like it can periodically, automatically check for Afib unlike the Whoop (?). The rest looks a little worse. But worth it to avoid a subscription fee. Not sure how Whoop stays in business TBH.

New comment by kj4211cash in "U.S. State Department pauses immigrant visa applications"

kj4211cash — Thu, 27 Aug 2026 01:56:10 +0000

When you think the only group we should allow to immigrate is white South Africans, then, yea, it's racism. At least be honest about it.

New comment by kj4211cash in "Young People Hate AI CEOs So Passionately That It's Almost Hard to Believe"

kj4211cash — Mon, 17 Aug 2026 04:29:34 +0000

You're probably right about (social) media being a factor but overindexing on Gini. Here's a chart that shows dramatically rising wealth gaps in the US: https://en.wikipedia.org/wiki/Income_inequality_in_the_Unite...

If I got this right Gini measures inequality in either income or spending but as Piketty showed we have crazy rising inequality in capital / wealth.

New comment by kj4211cash in "Young People Hate AI CEOs So Passionately That It's Almost Hard to Believe"

kj4211cash — Mon, 17 Aug 2026 00:34:29 +0000

I wonder how much of this is caused by income inequality. There are some young people I talk to that are genuinely worried about whether AI will take all the jobs. But there are a lot more that rightfully realize that they probably can't afford the middle class life their parents had and are annoyed at all the money AI is hoovering up and how rich these CEOs are. And that's the surface level. There's all sorts of resentment that hasn't really been thought through and wouldn't exist if we had the sort of real growth in lower- and middle-class incomes that we used to.

New comment by kj4211cash in "US hires over 2k video gamers as air traffic controllers"

kj4211cash — Wed, 12 Aug 2026 04:01:11 +0000

Worked in this area for a couple of years. We have automated collision avoidance systems and have for years. But things can go off nominal fast and you don't want passenger aircraft making drastic maneuvers that fast. Because conditions can change so fast, queueing theory isn't that useful either. It's useful for more strategic as opposed to tactical air traffic control, what we call air traffic flow management. There's been a ton of research in this area for decades, for example at the National Center of Excellence in Aviation Operations Research (NEXTOR) and at NASA's Aviation Systems division. I could say a lot more offline about why, in my humble opinion, progress has been unbelievably slow, but the short answer is that it's government plus modern day academia operating in an environment where funding is low and risk tolerance is lower.

New comment by kj4211cash in "The revenge of the philosophy majors"

kj4211cash — Wed, 08 Jul 2026 12:53:23 +0000

I think this line of thinking is a bit dangerous. It reminds me when I used to teach in a Civil Engineering department and the other faculty members focused exclusively on how well our coursework prepared our students to become civil engineers. Of course, very few of our students actually did become civil engineers and those that did both required years of additional training and often didn't last long in the profession before transitioning to something else. I used to teach maths and decision making. Had numerous students thank me later on for teaching some of the only material they actually used in their (non-civil-engineering) careers. No one knows what students will do post graduation. One of the best things we can do is to give them tools that are broadly useful.

New comment by kj4211cash in "The Doorman's Fallacy in action"

kj4211cash — Fri, 26 Jun 2026 11:49:24 +0000

I had a particularly bad experience with a hotel in Silicon Valley that had outsourced the front desk duties to remote workers. I was stuck outside in the rain, fighting a bad internet connection, trying to check-in. Probably saved them the space taken up by a front desk inside the hotel but I made a mental note never to use that hotel chain again.

New comment by kj4211cash in "My Mathematical Regression"

kj4211cash — Tue, 23 Jun 2026 12:52:27 +0000

This is basically my professional career. I've stayed 5+ years at the same place now and it's gotten to the point where people ask for me to build an optimization before it's even clear they have a problem amenable to optimization. Yay! My work has a good rep. But also I'm called upon entirely too frequently to explain work I did years ago or to answer questions like which constraint "comes first". Honestly it's getting very tiring. I think a switch to a new company would help but I wonder what will happen to the optimization work at my current company after I leave. It's weird that such a useful academic field still feels like black magic to much of corporate America. I guess it's just sophisticated enough.

New comment by kj4211cash in "How Madrid built its metro cheaply (2024)"

kj4211cash — Thu, 18 Jun 2026 12:41:33 +0000

The two things you reference are very loosely related. I studied Transportation Engineering in the Civil department at UC Berkeley. I have always been very interested in public transportation. But I work as a Data Scientist in Silicon Valley rather than at one of the public transportation agencies. Because it pays roughly 10x as much. Every single one of the smartest people I went to school with is also now working in tech in Silicon Valley. A lot work on stuff like advertising optimization. Sigh.

New comment by kj4211cash in "How to earn a billion dollars"

kj4211cash — Mon, 15 Jun 2026 13:01:16 +0000

The politician wasn't making a statement about startups or growth rates. She was making a statement about what it means to "earn" money.

New comment by kj4211cash in "What if remote working, not AI, is to blame for weak junior hiring?"

kj4211cash — Mon, 01 Jun 2026 12:34:02 +0000

Yes! I'm "only" a parent of 3 and live nowhere near my coworkers and would be happiest never going to the office. I have been told to travel across the country to HQ every 2 months for vague reasons. I wish I could better articulate to my managers the costs of this policy to my family. Usually female managers understand.

New comment by kj4211cash in "Rising seas will swallow New Orleans. People need to start relocating now"

kj4211cash — Tue, 26 May 2026 04:26:35 +0000

Hmmm... On the one hand, yes, silt deposition would tend to expand the delta and that's what you saw over the last 5,000 years up until the 1930's. And yes, it was work done by the Corps of Engineers to fix the course of the Mississippi River that broke this system. That plus logging, oil and gas extraction, and tons of other "local land use" things then led to sinking ground levels. As the article mentions, the governor cancelled a(n expensive) effort that would have resulted in more silt deposition ... in the general area that most experts think would have helped.

On the other hand, the silt wasn't ever being deposited in large quantities in New Orleans itself, but more in other places. The delta is huge. New Orleans is famously below sea level and always has been. There's always been hurricanes. It's always been dangerous to live there and I'm not sure you can blame the dynamic nature of the river.

New comment by kj4211cash in "Rising seas will swallow New Orleans. People need to start relocating now"

kj4211cash — Mon, 25 May 2026 21:32:40 +0000

Yup. The article mentions this, briefly.