μαθητής （学生）

@SawyerMerritt @Tesla Bad at so many levels

Here’s what happens when you hit an FSD streak milestone on @Tesla V14.3.4

@ChuckCook @LimitingThe @wholemars Tesla should be safety first 😔

@wholemars Make jokes all you want. My experience is that this is not the way to build a safe driving system.

Chuck Cook just had a heart attack

@DrPhiltill As people become bored post AI, they will likely make babies

I think demographic collapse in so many countries is tragic but I honestly think robotics and AI are developing fast enough that production and sophistication of the supply chain will be maintained. Thus, I don’t see this as civilizational collapse or national emergency in any high-tech nation. Longer-term, I think population dynamics will naturally select for people who want more babies, which should restore a higher birthrate, and life extension will eventually also help. Am I missing something?

@DKThomp @JesusFerna7026 Should be good news, as technology changes very fast

Earlier this year, I was very skeptical of the claim that smartphones reduced birthrates, because fertility declined so, so long before the arrival of smartphones. But @JesusFerna7026 changed my mind, and studies like this have confirmed that my mind should stay changed. The way I think about now is something like this: One set of factors best describes why birthrates declined toward 2 around the world in the last few decades—modernization, contraception, women's education and social freedom, etc. But another set of factors seems to better describe why birthrates have fallen toward 1 and below one in many places and among many groups. And smartphones belong in the second category.

@LesiaLVD Team Europe

Armenia chooses to say fuck Russia

新宿は豪雨

@LunarCitizens @NASA @SpaceX Does it make sense against moon-based?

James Webb primary mirror: 6.5 m Ariane 5 fairing: 5.4 m → Webb had to fold like origami Starship cargo bay: 9 m Ø × 22 m H (~1,000 m³) In the 2000s NASA imagined a 16 m “Super Webb”, but impossible then. Why not put it back on the schedule? We could finally see even deeper. #JWST #Starship

@ohtani_tani25 珍しい

岐阜の山の中で出会った、お地蔵様の群れ

@PeterSweden7 Heavy words

Sverige var en gång i tiden bland de tryggaste länderna i världen. Nu är Sverige bland de länder med högst antal våldtäkter i världen. Nu har Sverige också flera sprängdåd än något annat land som inte är i krig. Det har gått fruktansvärt illa för vårat land.

@saylor That is ironic coming from you though

Happy Bitcoin Pizza Day! 🍕

@eyeonaxis Brilliant

A woman and her dog in a dreamlike suburban scene. Germany, 1972, by Ernst Haas

@JesusFerna7026 That clarifies it. Getting to 3 certainly requires starting early enough, having money, *and* some sort of strong believe in family = happiness/duty/etc

Let me lay out the unpleasant arithmetic of the replacement rate, and why a modern society finds it so hard to reach. A population of 100 women in an advanced economy needs 210 children to replace itself. Why? Absent sex-selective practices, roughly 105 boys are born for every 100 girls. Evolution overshoots male births because boys are more prone to early death from accidents and disease. Therefore, of 210 children, about 108 are boys and 102 are girls. Not all girls reach the midpoint of their fertile age: accidents, suicide, homicide, and illness take some. In an advanced economy, about 98% of them survive, leaving 100 women to replace the original 100. Now consider the distribution of children per woman. Imagine 15 women have no children. Five do so by choice, for various reasons (professional, affective, religious). Ten face unfixable fertility problems, theirs or their partner’s. The 10% figure is conservative: the medical literature points to around 13%, and that does not even count male fertility problems. Of the remaining 85, 10 have one child, 60 have two, 10 have three, and 5 have four. I am stopping at four to keep the post concise; very few women in younger cohorts have five or more children, but I could adapt the example to account for them. Hence, the 100 women in this population have 180 children, for a completed fertility rate of 1.8. Interestingly, this is roughly the rate we saw in many advanced economies until the early 1990s, and in the U.S. until around 2008. But we are still 30 children short of replacement! Voluntary childlessness is only 5%. Three-quarters of women have two or more children. Look around: most of your friends will have two, plenty will have three or four. And yet, we are well below replacement. You would not look at this population and call it selfish (is having two kids hedonistic?) or accuse it of losing family values (only 5% of women are choosing voluntarily not to have children). The point is simpler. To reach 210 births, you need a substantial share of women to have three or more children. Two as the “normal” pattern will not get you there. And modern society makes three or more a costly proposition for most families. Of course, current fertility rates in most advanced economies are well below 1.8. But my point is that, under present social arrangements, we should not expect 2.1, even if (to humor last weekend’s debate) we banned smartphones and TikTok. We need many, many more families with three or four children. More pointedly, there is no self-regulating mechanism that pushes a society back to 2.1. The market-clearing analogy many economists use is flawed; scarcity feedback does not work the same way. (Another post on this another day.) And, as I often read, the claim that “nature” somehow regulates current overpopulation is just childish mumbo jumbo. So yes, the arithmetic of replacement rate is unpleasant.

@Yuji_48 Viewpoint or drone?

昼と夜の境目を走るような、福島県の水を張った田んぼを駆け抜けるJR水郡線。

@japan_nobunaga The requirement to be ‘like everybody else’ in practice goes much deeper though. If you are independently minded, it is pretty much game over: you will be accepted, but with a persistent reticence.

To those thinking of moving to Japan, let me be honest with you. On the train, we don't talk on the phone. In a quiet street, we don't shout. At a restaurant, we wait in line — even when no one is watching. We bow to strangers. We pay before we receive. We apologize before we explain. These aren't rules. There's no law for any of them. They are just 1,500 years of small daily promises we keep, without being asked. If you can love that, you will love Japan. And Japan will love you back. If you can't, please — think it through carefully. For your sake, and ours. 🇯🇵

@JesusFerna7026 I would like to understand how typical individuals experience the ‘choice’ of having children, not just correlation data. Maybe LLMs could help gather the kind of ‘interview like’ data that would be otherwise impractical to produce. Or is this irrelevant/obvious?

Smartphones are not the explanation for the recent decline in fertility. Instead, they are an accelerator of deeper forces already at work. Let’s start with the facts. Fertility is falling almost everywhere: in rich, middle-income, and poor countries; in secular and religious countries; and in countries with high and low levels of gender equality. The decline accelerated around 2014. So, no country-specific explanation will work unless you are willing to believe that 200 distinct country-specific explanations arrived at roughly the same time. Smartphones look like the obvious candidate: the first iPhone was released in 2007, and global adoption has been astonishingly fast. Economists understand the first major decline in fertility in advanced economies, from 6 or 7 children per woman throughout most of human history to about 1.8, that occurred between the early 1800s and roughly 1970, well before smartphones. The main drivers were a sharp fall in child mortality (effective fertility was rarely above 3 and often close to 2) and the shift from a low-skill, rural agrarian economy to a high-skill, urban industrial one. We have quantitative models that fit these facts well. Country-specific factors mattered too, of course. Proximity to low-fertility neighbors accelerated Hungary’s decline, while fragmented landowning structures accelerated France’s. But these were second-order mechanisms. This is also why most economists long considered Paul Ehrlich’s doom scenarios implausible. We forecast that fertility in middle- and low-income economies would follow the same path as in the rich, probably faster, because reductions in child mortality reached India or Africa at lower income levels (medical technology is nearly universal, and most gains come from handwashing and cheap antibiotics, not Mayo Clinic-level care). Much of what we see in Africa or parts of Latin America today is still that old story. But in the 1980s, a new pattern appeared. Japan and Italy fell below 1.8, the level we had thought was the new floor. By 1990, Japan was at 1.54 and Italy at 1.36. This second fertility decline began in Japan and Italy earlier than elsewhere, driven by country-specific factors, but the underlying dynamics were widespread: secularization, an education arms race, expensive housing, the dissolution of old social networks, and the shift to a service economy in which women’s bargaining power within the household is higher. The U.S. lagged because secularization came later, suburban housing remained relatively cheap, and African American fertility was still high. U.S. demographic patterns are exceptional and skew how academics (most of whom are in the U.S.) and the New York Times see the world. My best guess is that, without smartphones, Italy’s 2025 fertility rate would be about 1.24 rather than 1.14. I doubt anyone will document an effect larger than 0.1-0.2. Italy was at 1.19 in 1995, not far from today’s 1.14. The TFR is cyclical due to tempo effects, so I do not read too much into the rise between 1995 and 2007 or the decline from 1.27 in 2019 to 1.14 today. The direct effect of smartphones is not zero, but it is not, by itself, that large. Where social media, in general, and smartphones, in particular, matter is in the diffusion of social norms. What would have taken 25 years now happens in 10. Social media are not the cause of fertility decline; modernity is. But they are a very fast accelerator. That is why social media are a major part of the story behind Guatemala (yes, Guatemala) going from 3.8 children per woman in 2005 to 1.9 in 2025. Without them, Guatemala would also have reached 1.9, just 20 years later. Modernity, in its current form, is incompatible with replacement-level fertility. By modernity, I do not mean capitalism: fertility fell earlier and faster in socialist economies than in market economies. Socialist Hungary fell below replacement in 1960, and socialist Czechoslovakia in 1966 (both experienced small, short-lived baby booms in the mid-1970s). By modernity, I mean a society organized around rational, large-scale systems and formalized knowledge. Countries will not converge to the same fertility rate. East Asia is likely stuck near 1, possibly below, given its unbalanced gender norms and toxic education systems. Latin America faces the same gender problem plus weak growth prospects, so I expect something around 1.2. Northern Europe has more egalitarian family structures and might hold near 1.5. The very religious societies are probably the only ones that will sustain 1.8. All of this could change with AI or changes in population composition. We will see. But on the current evidence, deep sub-replacement fertility is the “new new normal.” Unless we reorganize our societies, better learn to handle it as best we can.

@Gerashchenko_en Delightful!

A very large fire in the Eastern part of Moscow. Locals report hearing an explosion before the fire.

@lexfridman Is this how you find your wife? :)

Form 1 - travel recommendation: form.jotform.com/261303042756046 Form 2 - coffee: form.jotform.com/230415467865159 General contact: lexfridman.com/contact/

I'm traveling the world for a bit, starting with China but then hopping around the globe, anywhere. Open to any adventure. No plans, only a backpack. Hoping to meet & get to know humans from all walks of life. The pic is from a long hike on the Great Wall. For me, as a fan of history, this was an epic experience. In China, first I'm visiting a few big cities & talking to engineers at the heart of China's AI revolution. After that, if feeling crazy enough, I'm hitchhiking (first time) across rural China for a few weeks. Hitchhiking because I think it's the best way to meet rural folks who I would otherwise never get the chance to meet. I hope to do the same in US and other places. I have a request, if you have a travel recommendation, fill out the form(s) below if you feel like it. Or share with folks who might have advice about such travel. Form 1 - travel recommendation: If you can, recommend to me an interesting place I should visit anywhere in the world. For this, fill out form 1. Not touristy stuff, but something off the beaten path, that tourists may not know about, but is legendary. It could be as remote as meeting a herder in the mountains who is a local legend. Asia, Middle East, Europe, India, South/North America, Africa, Australia, anywhere. In China, I'm hoping to visit maybe Heibei, Shanxi, Shaanxi, Gansu, Sichuan, Yunnan, etc, so recommendations for spots to visit are helpful. Form 2 - coffee: If you want to grab a coffee with me anywhere in the world, fill out form 2 (please don't use form 1 for that). Anyway, I hectically tossed stuff in backpack. Realizing I don't have a clear plan of any kind, which is probably the only way to do it. LFG. Love you all ❤️

@berniemoreno Revolutionary

🚨 The banking cartel is in full panic mode. 🚨 While Americans were celebrating Mother’s Day with their families, the CEO of the American Bankers Association sent a frantic alert to every bank CEO in the country, demanding “immediate engagement” to lobby Senators and kill stablecoins that would finally let everyday Americans earn real yields on their own money. This line in the letter sticks out: “we believe committee members may not be fully aware of the risks to the economy by the stablecoin loophole.” That’s both intellectually dishonest and simultaneously demeaning. First, there is no “loophole.” This entire issue was litigated during the GENIUS Act debate. @BillHagertyTN worked tirelessly on this issue and this statement is an insult to his and others work. For decades, these banks have treated your deposits like their personal piggy bank, paying you next to nothing while lending YOUR money out for massive profits and executive bonuses. During the Biden era, these same banks worked hand-in-glove with @SenWarren and her allies to debank Americans, including President Trump’s own family. They shut down accounts of conservatives, patriots, and anyone who dared challenge the regime, all while regulators applied pressure under schemes like Operation Choke Point 2.0. It wasn’t about risk. It was about political control. Now that innovative stablecoins threaten to break their monopoly and give you actual financial freedom? They’re running to Congress again, screaming about “threats to economic growth and financial stability.” Translation: Protect the racket at all costs. The Senate Banking Committee votes on landmark crypto legislation this Thursday. As a member of that committee, my message is clear: Hands off the people’s money. Let Americans choose real competition and better returns. No more shielding Wall Street from the future. The banking elite’s days of rigging the system and debanking their political enemies are over. Innovation, freedom, and the American people will win. I’m voting to break the cartel.

@p_ferragu The goal is AGI. Everything else is peanuts.

Don’t underestimate the value of owning compute. Labs without a balance sheet & renting pay a 25-30% GM on compute and won’t have depreciated and still efficient chips in 5 years. This hurts. Big time. Meaningful competitive advantage for spaceX and Google.