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A learning a day, since May 12 2008, by Rohan.
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Contrails

2025-10-30 19:44:00

Hannah Ritchie has a typically thoughtful analysis on how we eliminating contrails could make a significant dent in carbon emissions from flying.

When you see a plane in the sky, you might see a small, white cloud-like trail behind it. Those are contrails (short for “condensation trails”).

These have a net-warming effect on the planet. And this effect is worse at night and in winter.

But here’s where things get interesting. Just 3% of the world’s flights generate most of the warming from contrails.

And a short change in flight path (1-2% increase) can mitigate this. This translates to less than $1 per ticket.

From Hannah – What would help a lot is increasing public awareness of the existence of contrails, their climate impacts, and how inexpensive it could be to eliminate them. There is a general understanding that decarbonising aviation is expensive, and this often means the aviation industry gets more of a free ride. But this is based on replacing jet fuel. If people were aware that it could cut a huge chunk of its footprint at a fraction of the cost, they might be more demanding.

Eliminating a few percent of the world’s warming is a big deal when the costs are so small. It seems insane to me that such a cheap solution is sitting there, completely untapped.

That and the reminder that there are often creative and inexpensive solutions out there for so many complex problems.

Floss before brushing

2025-10-29 19:38:00

A dental hygienist we met recently told us we should floss before brushing instead of after.

“No way” was my first reaction. I thought I had my dental hygiene routine down.

It turns out she was right. Flossing first loosens and removes food particles and plaque between your teeth that your toothbrush can’t reach.

Once the spaces between teeth are clean, toothpaste’s fluoride can reach more surfaces and protect them better.

This logic made sense. And it has shown up in studies too (like this one).

3 takeaways –

(1) It is amazing how you can do something every day for so many years and realize there is a better way to do it.

(2) It is more important to floss than worry about the order. So that’s the first habit to nail.

(3) And assuming you do, floss before brushing.

Everything is television

2025-10-28 19:32:00

A couple weeks ago, I wrote about the evolution of our behavior with television – or “the idiot box.” My hypothesis was that the cause for the global decline in intelligence could be attributed to the fact that we now get to carry this box in our pocket.

Derek Thompson had a beautiful articulation of this in his post – “Everything is television.” A few excerpts –

Social media: Social media has evolved from text to photo to video to streams of text, photo, and video, and finally, it seems to have reached a kind of settled end state, in which TikTok and Meta are trying to become the same thing: a screen showing hours and hours of video made by people we don’t know. Social media has turned into television.

Podcasts: But the most successful podcasts these days are all becoming YouTube shows. Industry analysts say consumption of video podcasts is growing twenty times faster than audio-only ones, and more than half of the world’s top shows now release video versions. YouTube has quietly become the most popular platform for podcasts, and it’s not even close.

Sora and Vibes: Even the architects of artificial intelligence, who imagine themselves on the path to creating the last invention, are busy building another infinite sequence of video made by people we don’t know. Even AI wants to be television.

Too much television: One implication of “everything is becoming television” is that there really is too much television—so much, in fact, that some TV is now made with the assumption that audiences are always already distracted and doing something else. Netflix producers reportedly instruct screenwriters to make plots as obvious as possible, to avoid confusing viewers who are half-watching—or quarter-watching, if that’s a thing now—while they scroll through their phones. 

Perhaps a great deal of television is not meant to absorb our attention, at all, but rather to dab away at it, to soak up tiny droplets of our sensory experience while our focus dances across other screens. You might even say that much television is not even made to be watched at all. It is made to flow. The play button is the point.

Gen Z: For five straight years, Gen Z has told pollsters that the thing they most want to be when they grow up is an “influencer.”

Inwardness: When literally everything becomes television, what disappears is not something so broad as intelligence (although that seems to be going, too) but something harder to put into words, and even harder to prove the value of. It’s something like inwardness. The capacity for solitude, for sustained attention, for meaning that penetrates inward rather than swipes away at the tip of a finger: These virtues feel out of step with a world where every medium is the same medium and everything in life converges to the value system of the same thing, which is television. I don’t have the answers here. But we should figure it out soon. The marble is still spinning, but it is reaching the bottom of the bowl.

Indeed.

Avoiding email scams – 3 tell-tale scams

2025-10-27 19:22:00

I used to talk or write about scams from a place of “let me help you not get scammed.” That changed when I went half-way down the path of getting scammed 5 years ago. Nothing like the knock from a near miss to instill some humility.

I’ve since become more observant about scams. And while text and phone scams are a different beast, I thought I’d share what I’ve come to realize are the 3 tell-tale signs of an attempted email scam:

(1) Random Gmail ID masquerading as an entity. In this case, “Oracle Health.” This is the first place to look.

(2) Contradictions in the email.

Celina started the email as a Senior Recruiter.

However, she ended the email as a Senior Public Relation Manager.

Aside from the fact that Public Relations was a mistake, such contradictions are common in email scam. I think they exist almost as a test for you – if you aren’t paying attention, you’re more likely to fall for such a scam.

The most extreme version of this is the email from the Nigerian Prince. If you’re falling for that in 2025, then maybe they deserve to take your money.

(3) Funky links. This particular email didn’t have a good example. But it helps to pay attention to links. Instead of Amazon.com/xx – a link might say Amazonxxxyyyzzz.com. It looks similar enough but, of course, it isn’t right.

It’s become a lot easier to check if something is spammy by just pasting the email into ChatGPT or Claude.

It’s also become a lot easier to spam and make these emails look more convincing. I’m sure the Gmail team spends a non-trivial portion of their time these days figuring out how to counter this.

Stay safe out there.

When you invest your love

2025-10-26 19:36:00

“In these bodies we will live, in these bodies we will die.
Where you invest your love, you invest your life”
| “Awake my Soul” by Mumford and Sons

It’s a beautiful to think about love and this life. Where we spend our love and attention tells the story of who we are.

Choose intentionally, we must.

The Empty Quarter

2025-10-25 19:01:00

Eric Weiner, who wrote “The Geography of Bliss,” has a way of making you fall in love with places. His travel memoir from visiting the desert made me think back to a time when I stayed in the desert.


On day two of my journey into the Empty Quarter, the world’s largest sand desert, an odd, unbidden calm swept over me. My breathing slowed. My mind no longer darted from thought to thought, like a chimpanzee with ADHD. I could think again.

I’m not sure how to explain this uncharacteristic tranquility. Maybe it was the way the desert light played across the sand, shifting from khaki to brown to Martian red in the course of only a few hours. Maybe it was the complete absence of even a trace of civilization: not a single road or building or other human, save my Bedouin guide Suhail. Maybe it was the lack of Internet connection or cell-phone signal.

Most likely it was some combination of the three, plus an elusive fourth element, one that for centuries has attracted people to this unforgiving land on the Arabian peninsula. It is a strange attraction, for there is nothing nice about the desert, “a bitter, desiccated land which knows nothing of gentleness or ease,” wrote Wilfred Thesiger, a 20th-century British explorer who crossed the Empty Quarter on camel and foot.

So, how to explain the unexpected beauty of this unforgiving, desolate land? What is the allure of a vast expanse of sand, and not much else? It boils down, I think, to a kind of desert essentialism. Everything we treasure in the non-desert world evaporates like water on hot sand. Money is of no use here, nor is reputation, fame, or any of the other ego food we spend so much time pursuing elsewhere.

Only two things that matter in the desert: water and shade, and neither are entirely under our control. “The desert teaches you never to take yourself too seriously,” says Belden Lane, a professor of theology.

Pierre Loti, a 19th-century French novelist and desert traveler, explains the appeal this way:

“You get drunk on light and space. You know the heady intoxication of just being able to breathe, just being alive…one has the illusion of truly being united with universal permanence and time.”

Deserts like the Empty Quarter strip us bare. They demand to know, “Who are you?” It is not interested in the various roles you play in more temperate climes—parent, son, employee, upstanding citizen—but only cares about the real you, the essential, naked you.

The Empty Quarter may be empty but that emptiness is not static. The color of the sand shifts, as do the sand dunes. They are enormous, rising to heights of eight or nine hundred feet. More like sand mountains than dunes. Each one looks different, too, their shape and contours changing with the prevailing winds. Here, the land literally shifts beneath your feet. There are two ways to react to such uncertainty: fear or faith. It is no coincidence, I think, that all three major monotheistic faiths were born in the desert.

The desert is a spiritual proving ground, an unforgiving crucible of sand and heat.

In the Torah, God leads the Israelites through the Sinai desert, even though a shorter route to the promised land existed. This was not a mistake (God doesn’t make mistakes.) The desert was a test. Were the Jews still shackled by the slave mindset? Were they tempted to return to the promise of a regular meal in Egypt, even if it came attached to shackles?

In the fourth and fifth century AD, renegade Christian monks retreated to the desert. “To me a town is a prison, and the desert loneliness a paradise,” wrote Saint Jerome, one of the “desert fathers,” as they are known. Some still do so today.

In the desert, death is never far away. I was reminded of that when I stumbled across the skeleton of a camel, its bones bleached bright white by the desert sun. When I went for a walk and briefly lost sight of my guide, I thought: if I don’t find him, I will die here. This was not a hypothetical. It was a certainty. Yet it is this nearness of death that makes us feel more alive.

Even a few days spent in the desert can have a lasting impact. As Wilfred Thesiger said, “No man can live this life [of a nomad]and emerge unchanged. He will have within him the yearning to return…for this cruel land can cast a spell which no temperate climate can match.”

Will I return to the Empty Quarter? Perhaps. But the real question, I think, is whether the desert, and the lessons it has taught me, stick. I sure hope so.


I had 3 takeaways.

First, his notes about desert essentialism is one I’ve found to be so true in nature. It’s just you – no titles, no status, and no wealth. Stripped of everything, you are forced to get to know yourself.

Second, I thought his observation about the two ways to react to the uncertainty of the desert (fear or faith) was powerful. It is much easy to talk about being rational when you live in a world with exponentially less daily uncertainty.

Finally, as much as Eric was talking about how the desert cast a spell on him, I found Eric’s writing cast a spell on me. A great reminder of the power of a well-crafted essay.