Jeff Kaufman
@jefftk.com
Contra dance musician, parent, effective altruist, biosurveillant, software engineer, blogger.
www.jefftk.com
www.jefftk.com
I hear people talking about "skyrocketing" rents, with the idea that rent is going up quickly. But when I look at the data what I see is that rent is high and stable. Which is still bad, but it's differently bad.
Rents Are High, But Not Skyrocketing
I hear people talking about
www.jefftk.com
January 8, 2026 at 2:41 AM
I hear people talking about "skyrocketing" rents, with the idea that rent is going up quickly. But when I look at the data what I see is that rent is high and stable. Which is still bad, but it's differently bad.
I counted each band and caller that played at a big contra dance event in 2025. Not because I wanted to make a big list of rankings, but it did let me make a big list of rankings:
Festival Stats 2025
Someone asked me which contra dance bands and callers played the most major gigs in 2025, which reminded me that I hadn't put out my annual post yet! Here's what I have, drawing from the big spreadsh...
www.jefftk.com
January 6, 2026 at 1:41 AM
I counted each band and caller that played at a big contra dance event in 2025. Not because I wanted to make a big list of rankings, but it did let me make a big list of rankings:
An American donating $10k could likely give $1k more by donating stock instead of selling it for cash to donate. More if the stock has gone up a lot or they're in a high tax bracket or high-tax area.
This applies to 501(c)3s (regular charities), but also 501(c)4s (advocacy) and other 501(c) orgs.
This applies to 501(c)3s (regular charities), but also 501(c)4s (advocacy) and other 501(c) orgs.
Don't Sell Stock to Donate
When you sell stock [1] you pay capital gains tax, but there's no tax if you donate the stock directly. Under a bunch of assumptions, someone donating $10k could likely increase their donations by ~$1...
www.jefftk.com
December 30, 2025 at 7:53 PM
An American donating $10k could likely give $1k more by donating stock instead of selling it for cash to donate. More if the stock has gone up a lot or they're in a high tax bracket or high-tax area.
This applies to 501(c)3s (regular charities), but also 501(c)4s (advocacy) and other 501(c) orgs.
This applies to 501(c)3s (regular charities), but also 501(c)4s (advocacy) and other 501(c) orgs.
I like writing retrospectives for things I'm involved in, especially if I'm likely to be involved in them in the future: it's a good place to set thoughts down so I can find them again, link materials I'm likely to want, and collect feedback. Here's one for Saturday night's Secular Solstice!
Boston Solstice 2025 Retrospective
I like writing retrospectives for things I'm involved in, especially if I'm likely to be involved in them in the future: it's a good place to set thoughts down so I can find them again, link materials...
www.jefftk.com
December 30, 2025 at 1:10 AM
I like writing retrospectives for things I'm involved in, especially if I'm likely to be involved in them in the future: it's a good place to set thoughts down so I can find them again, link materials I'm likely to want, and collect feedback. Here's one for Saturday night's Secular Solstice!
It's common for people to say that Medford limits houses and apartments to at most three unrelated adults, and Somerville and Boston to four. As far as I can tell this is false.
Shared Houses Illegal?
As part of the general discourse around cost of living, Julia and I were talking about families sharing housing. This turned into us each writing a post ( mine, hers), but is it actually legal for a f...
www.jefftk.com
December 27, 2025 at 3:09 PM
It's common for people to say that Medford limits houses and apartments to at most three unrelated adults, and Somerville and Boston to four. As far as I can tell this is false.
The world is divided into plain text and rich text, but I want comfortable text:
Yes: Lists, links, bold, italics, ...
No: Colors, fonts, text sizing, text alignment, ...
I made a Mac utility that limits copied text to what you can represent in Markdown.
Yes: Lists, links, bold, italics, ...
No: Colors, fonts, text sizing, text alignment, ...
I made a Mac utility that limits copied text to what you can represent in Markdown.
Clipboard Normalization
The world is divided into plain text and rich text, but this is often not what I want. I want comfortable text: Yes: Lists, links, blockquotes, code blocks, inline code, bold, italics, underlining...
www.jefftk.com
December 25, 2025 at 1:57 PM
The world is divided into plain text and rich text, but I want comfortable text:
Yes: Lists, links, bold, italics, ...
No: Colors, fonts, text sizing, text alignment, ...
I made a Mac utility that limits copied text to what you can represent in Markdown.
Yes: Lists, links, bold, italics, ...
No: Colors, fonts, text sizing, text alignment, ...
I made a Mac utility that limits copied text to what you can represent in Markdown.
We didn't wait to buy a house (or have multiple bedrooms) before having kids, and I think that was the right choice for us. "Put lots of people in a medium-sized space" has always been a major way people saved money on housing, and is still a legal and practical (though not ideal) option today.
Kids and Space
There's been a lot of discussion over the last month on whether it's still possible to raise kids without being rich. If you need to buy a house where each kid has their own room, yes, that's expensi...
www.jefftk.com
December 24, 2025 at 3:29 PM
We didn't wait to buy a house (or have multiple bedrooms) before having kids, and I think that was the right choice for us. "Put lots of people in a medium-sized space" has always been a major way people saved money on housing, and is still a legal and practical (though not ideal) option today.
When someone releases code publicly under some kind of "look but don't touch" terms there's reliably some kind of "X is open source" / "no, X is source available" / "that's nuts" argument. But there are many cases where the opposite of "closed X" is a different thing from "open X".
Open Source is a Normal Term
Every time someone releases code publicly under some kind of
www.jefftk.com
December 23, 2025 at 3:34 PM
When someone releases code publicly under some kind of "look but don't touch" terms there's reliably some kind of "X is open source" / "no, X is source available" / "that's nuts" argument. But there are many cases where the opposite of "closed X" is a different thing from "open X".
Saturday evening (12/27) I'm going to be coordinating music for the 2025 Boston Secular Solstice. If singing and speeches celebrating human progress and discussing the dangers we still face sounds like something you might like, it would be great to see you there!
Boston Secular Solstice Celebration 2025 — LessWrong
As the year comes to an end, the days have grown shorter and the nights have grown longer. Tonight we remember the ancient days of humanity's past, a…
www.lesswrong.com
December 21, 2025 at 9:23 PM
Saturday evening (12/27) I'm going to be coordinating music for the 2025 Boston Secular Solstice. If singing and speeches celebrating human progress and discussing the dangers we still face sounds like something you might like, it would be great to see you there!
We've been stuck on the red line between Porter and Harvard for 70min. They're working on hooking up a rescue train.
Intercom: "when you get up to the front, take off the sleet scraper"
Random passenger in our car: "will do!"
Intercom: "when you get up to the front, take off the sleet scraper"
Random passenger in our car: "will do!"
December 15, 2025 at 2:52 PM
We've been stuck on the red line between Porter and Harvard for 70min. They're working on hooking up a rescue train.
Intercom: "when you get up to the front, take off the sleet scraper"
Random passenger in our car: "will do!"
Intercom: "when you get up to the front, take off the sleet scraper"
Random passenger in our car: "will do!"
My house has radiators for heat. There are fewer heating loops than rooms, and it's not very well balanced. Fixing this properly involves hiring a plumber, but we can make it much better by just putting a small fan on the radiator where we want more output.
Fanning Radiators
My house has radiators for heat. There are three heating loops (
www.jefftk.com
December 14, 2025 at 9:09 PM
My house has radiators for heat. There are fewer heating loops than rooms, and it's not very well balanced. Fixing this properly involves hiring a plumber, but we can make it much better by just putting a small fan on the radiator where we want more output.
Far-UVC is something people have talked about for years in a "that would be great, if you could buy it" sort of way. But the future is now, and it costs $500. I think we're now at the point where dances, churches, offices, rationalist group houses, schools, etc. should consider them.
You Can Just Buy Far-UVC
Far-UVC is something people have talked about for years in a
www.jefftk.com
December 13, 2025 at 1:10 PM
Far-UVC is something people have talked about for years in a "that would be great, if you could buy it" sort of way. But the future is now, and it costs $500. I think we're now at the point where dances, churches, offices, rationalist group houses, schools, etc. should consider them.
I move my music pedalboard around in a suitcase. A few months ago I used spray adhesive to attach foam padding to the case instead of having it loose. It's still good and tight!
Permanently Padding a Suitcase
My current setup for playing dances is a bit excessive, and transport my pedalboard in an old hardshell suitcase. [1] There's no built-in padding, so I use sheets of foam to protect my equipment. Ini...
www.jefftk.com
December 13, 2025 at 3:10 AM
I move my music pedalboard around in a suitcase. A few months ago I used spray adhesive to attach foam padding to the case instead of having it loose. It's still good and tight!
I used to need to take my access card out of my wallet to tap it, but then I realized I could tape a piece of tinfoil to the back.
I often put up with annoyances instead of thinking about how to fix them (which overall makes my life better!) but in this case I should have done something sooner.
I often put up with annoyances instead of thinking about how to fix them (which overall makes my life better!) but in this case I should have done something sooner.
The Fantastic Piece of Tinfoil in my Wallet
The gates in the lobby of my workplace annoyed me for years: they would often reject my access card, and I'd need to tap several times. After a while I realized that the reader was getting confused by...
www.jefftk.com
December 12, 2025 at 3:32 AM
I used to need to take my access card out of my wallet to tap it, but then I realized I could tape a piece of tinfoil to the back.
I often put up with annoyances instead of thinking about how to fix them (which overall makes my life better!) but in this case I should have done something sooner.
I often put up with annoyances instead of thinking about how to fix them (which overall makes my life better!) but in this case I should have done something sooner.
On a road trip, you can call in an order to a pizza place you'll be driving past in half an hour. Combining the benefits of food that takes a while to make with not having to wait around!
Ordering Pizza Ahead While Driving
On a road trip there are a few common options for food: Bring food Grocery stores Drive throughs Places that take significant time to prepare food Bringing food or going to a grocery store a...
www.jefftk.com
December 7, 2025 at 1:56 AM
On a road trip, you can call in an order to a pizza place you'll be driving past in half an hour. Combining the benefits of food that takes a while to make with not having to wait around!
Anthropic has many employees with an EA-ish outlook, who may soon have a lot of money. If you also have that kind of outlook, money donated sooner will likely be much higher impact.
Front-Load Giving Because of Anthropic Donors?
Summary: Anthropic has many employees with an EA-ish outlook, who may soon have a lot of money. If you also have that kind of outlook, money donated sooner will likely be much higher impact. It's De...
www.jefftk.com
December 4, 2025 at 2:27 AM
Anthropic has many employees with an EA-ish outlook, who may soon have a lot of money. If you also have that kind of outlook, money donated sooner will likely be much higher impact.
It can be hard to get the kids to practice their instruments. Sometimes they're having trouble focusing, don't like their assigned piece, or are just grumpy. One thing I'll offer them in these cases is "busking practice", where instead of practicing their assigned piece we pretend we're busking.
Busking Practice
It can be hard to get the kids to practice their instruments. Sometimes they're having trouble focusing, don't like their assigned piece, or are just grumpy. One thing I'll offer them in these cases i...
www.jefftk.com
November 23, 2025 at 3:15 PM
It can be hard to get the kids to practice their instruments. Sometimes they're having trouble focusing, don't like their assigned piece, or are just grumpy. One thing I'll offer them in these cases is "busking practice", where instead of practicing their assigned piece we pretend we're busking.
We clean drinking water all the time, not just in response to cholera outbreaks. To have clean air in emergencies, we need to figure out how to have clean air every day. The benefits of widespread deployment of air purifiers, far-UVC, etc are very high even before you count the biosecurity impact.
Everyday Clean Air
When the next pandemic hits our ability to stop it will depend on the infrastructure we already have in place. A key missing piece is clean indoor air. An airborne pathogen can be very hard to contain...
www.jefftk.com
November 15, 2025 at 12:52 AM
We clean drinking water all the time, not just in response to cholera outbreaks. To have clean air in emergencies, we need to figure out how to have clean air every day. The benefits of widespread deployment of air purifiers, far-UVC, etc are very high even before you count the biosecurity impact.
I wanted to link an explanation of how far-UVC works, why you might want to use it to clean indoor air, and what we know about its safety. I didn't find anything I liked, so I made something: faruvc.org
Background: jefftk.com/p/introducing-faruvc-org
Background: jefftk.com/p/introducing-faruvc-org
faruvc.org
November 12, 2025 at 3:58 PM
I wanted to link an explanation of how far-UVC works, why you might want to use it to clean indoor air, and what we know about its safety. I didn't find anything I liked, so I made something: faruvc.org
Background: jefftk.com/p/introducing-faruvc-org
Background: jefftk.com/p/introducing-faruvc-org
The kids told me they wanted to watch a "blue E" but Disney wasn't working. I told them I could solve their problem, but they weren't amused.
November 12, 2025 at 12:54 AM
The kids told me they wanted to watch a "blue E" but Disney wasn't working. I told them I could solve their problem, but they weren't amused.
Looking up the history, apparently this is not a pun!
November 11, 2025 at 12:17 AM
Looking up the history, apparently this is not a pun!
Picking up checked bags at Logan. Old displays say carousel 4. New ones say 6. Announcer repeatedly says 3. Bags came out on 2.
November 10, 2025 at 12:11 PM
Picking up checked bags at Logan. Old displays say carousel 4. New ones say 6. Announcer repeatedly says 3. Bags came out on 2.
Getting ready for far UVC starting tomorrow at BIDA! blog.bidadance.org/2025/11/maki...
November 2, 2025 at 1:55 AM
Getting ready for far UVC starting tomorrow at BIDA! blog.bidadance.org/2025/11/maki...
When I saw the recent Atlantic article on Florida train deaths I guessed we were making a big deal over it because it was the train was big and new, and actually we're better off overall. Turns out no: Brightline is just really deadly, not just for a train, but even relative to driving.
Brightline is Actually Pretty Dangerous
Per the Atlantic's A 'Death Train' is Haunting South Florida: According to Federal Railroad Administration data, the Brightline has been involved in at least 185 fatalities, 148 of which were beli...
www.jefftk.com
October 26, 2025 at 12:43 PM
When I saw the recent Atlantic article on Florida train deaths I guessed we were making a big deal over it because it was the train was big and new, and actually we're better off overall. Turns out no: Brightline is just really deadly, not just for a train, but even relative to driving.
For deploying far UVC to clean the air at a dance event, I modeled the difference between putting a lamp in each corner (theoretical ideal) vs one stand with four lamps on stage (logistically better). Efficacy goes down 5.6%, but it's within safety limits.
Assessing Far UVC Positioning
I help organize a contra dance in a crowded dance hall, and we've been considering using far UVC to clean the air, reducing infection risk from COVID, flu, and other airborne pathogens. We recently p...
www.jefftk.com
October 25, 2025 at 1:55 PM
For deploying far UVC to clean the air at a dance event, I modeled the difference between putting a lamp in each corner (theoretical ideal) vs one stand with four lamps on stage (logistically better). Efficacy goes down 5.6%, but it's within safety limits.