I live in Paris and bike nearly every day, with my electric bike, or sometimes the city's velib rental bikes, sometimes private rental bikes (Uber, Dott, Voi). I love the drastic push to add more bike lanes, and reduce car lanes. I don't own a car in this city. Don't need one.
I think there'll continue to be growth in page sizes, but then maybe we'll consider efficiency, or the NYTimes shuts down and the 20MB page will be the liquidators selling the domain. Maybe we don't even use domains by then as everything is on an app.
Yup. I typed my French ZIP code (code postal) and this guessed a US city...
But the author has a point. Combine it with some approximate country-level geolocate of the web client and this would work perfectly 99% of the time modulo edge cases like VPN users.
"Someone who hated computers so much that she had the secretary print out her emails so she could read them was interrogated for hours about hacking into Agency networks [...] there was often a gross mismatch between a person and the accusations made against them."
Well, isn't it expected? If I were a double agent, faking that I was so computer illiterate that I ask my emails to be printed out would be the perfect cover for my hacking =:-)
> I spend most of my time editing in Emacs. I read and send mail with Emacs using M-x rmail and C-x m. I have no experience with any other email client programs.
You may have confused this with his somewhat idiosyncratic way of browsing the web:
> I generally do not connect to web sites from my own machine, aside from a few sites I have some special relationship with. I usually fetch web pages from other sites by sending mail to a program (see https://git.savannah.gnu.org/git/womb/hacks.git) that fetches them, much like wget, and then mails them back to me. Then I look at them using a web browser, unless it is easy to see the text in the HTML page directly. I usually try lynx first, then a graphical browser if the page needs it.
Donald Knuth, on the other hand, quit email in 1990, after using it for 15 years:
> I have been a happy man ever since January 1, 1990, when I no longer had an email address. I'd used email since about 1975, and it seems to me that 15 years of email is plenty for one lifetime.
Since then, he prefers snail mail but has a secretary who will print out his emails:
> My secretary also prints out all nonspam email messages addressed to taocp@cs.stanford.edu or knuth-bug@cs.stanford.edu, so that I can reply with written comments when I have a chance. If I run across such a message that was misaddressed --- I mean, if the message asks a question instead of reporting an error --- I try not to get angry.
Mistral's Le Chat also fails spectacularly. Although interestingly it assumes that the "walk" option means you are carrying washing supplies back and forth in order to wash the car while it's parked at home. I wonder if the other models assume this is what you mean, IOW they may not know how a "car wash" normally operates.
"""
Great question! Here are a few things to consider:
If you walk: It’s only 50 meters, so it’s a very short distance—less than a minute on foot.
You’ll avoid getting your car dirty again on the way to the car wash.
It’s a quick way to stretch your legs and save a tiny bit of fuel.
If you drive: It’s so close that driving might feel unnecessary, but it could save you from carrying any supplies (like vacuum cleaners or cleaning products) back and forth. If the weather is bad (rain, extreme heat, etc.), driving might be more comfortable.
Verdict: Walking is probably the easiest and most practical choice for such a short distance, unless you have a specific reason to drive. What’s the weather like where you are? That might help decide!
As an Android user, I truly don't understand this "pressure". I exchange SMS/MMS with various users, some Android, some iPhone. I am in group chats with both Android and iPhone users. I feel there is no major issue. It's interoperable. We all see each other's emojis/photos/videos/etc. There are only minor technical rough edges: for example an iPhone's user emoji reaction sometimes (not always?) shows up as separate text instead of the emoji appended at the bottom of the text bubble... And I am pretty sure videos are sent in a lower quality. But is any of this really enough to cause a "blue bubble pressure"?
I asked ChatGPT to explain but only got this vague answer: "Group chats with a mix of iPhone and non-iPhone users can be less seamless (e.g., lower video quality, no read receipts, or issues with group chat features)."
I had to open my texts to check: I indeed have read receipts when texting Android users, but not iPhone users. And this is funny but up to this very second, I had never noticed this difference... because, at least to me, read receipts is such a minor feature that I rely on very infrequently.
This leaves me still as perplex: why the "blue bubble pressure"?
I dislike with passion the answer "because Rayleigh scattering". When someone asks why, especially if a child asks, the default answer should be the simplest correct answer:
Because it's the color of the atmosphere, specifically nitrogen and oxygen! It's technically correct to state this.
Gasp! But aren't nitrogen and oxygen usually described as "colorless"? Well, yes but... If they were perfectly colorless, the sky would be black. It's technically more correct to describe them as nearly colorless and very slightly blue. Very slightly because you need to see through kilometers of atmosphere to perceive the blue. It doesn't matter if the color is caused by absorption, or reflection, or (Rayleigh) scattering of certain wavelengths. The "color" of an object is simply the color you perceive with your eyes. If you perceive blue, it's technically correct to say its color is blue.
It's like saying plants are green because green is the color of chlorophyll. And in the case of chlorophyll, the color is caused by absorption not by scattering. But the physics is irrelevant. Green is its color.
Q: But sunsets/sunrises are red & orange not blue! A: the simplest answer is: color of an object can change under different light conditions. Specifically in this example, when seeing the sun through not kilometers but hundred of kilometers of atmosphere, all the blue-ish wavelengths have been scattered in random directions so only the red-ish wavelengths remain, thus the atmosphere is illuminated by progressively redder and redder light as the photons travel longer and longer distances through the atmosphere.
At least my mental model of color before I learned the details in physics and chemistry was that of a property of surfaces, so your explanation wouldn't have served me. I would have expected, that the light becomes blue as part of the transition from "empty space" into "air", not as part of the "flight" through the air.
You can conceptualize Rayleigh scattering exactly like you did so it doesn't conflict with my explanation: as light hits the "surface" of nitrogen and oxygen molecules, it "reflects" (scatters) blue wavelengths.
I was talking about the understanding of a child, which didn't learned physics and chemistry yet, so there are also no atoms. Of course now I know about them, but at the same time, what I used to call a "surface", simple doesn't exist anymore.
I'm surprised that there were downvotes. This is an excellent answer, and better interfaces between linguistic definitions of color and physicists' than saying "Rayleigh scattering impacts blue more than red"!
Well this is just a personal website, so it is has much (or as little) information as the owner wants to put up. The legal notice page (in German) tells you it's the site of a certain Dr. Ulrich Deuschle: https://www.udeuschle.de/impressum.html
Hi Tom it's Marc, I'm glad to see you finished your sightline project ! Any clue why you report the longest sightline as "530.8 km" when it seems to be actually 538.1 km? That's what my code calculated (https://news.ycombinator.com/item?id=45512970) that's what Dr. Ulrich Deuschle also calculates (https://www.udeuschle.de/panoramas/panqueryfull.aspx?mode=ne...) You, Deuschle, and I all use the same DEM data (https://www.viewfinderpanoramas.org/Coverage%20map%20viewfin...) and the same refraction coeff (0.13), and nearly the same camera height (1.5m for me, 2.0m for Deuschle, and 1.65m for you—and these differing heights make no difference given the coarse DEM resolution). Something must be slighly off in your computations? Or do you think both Deuschle and I are wrong?
Edit: to be clear the difference stems from our coordinates. Our starting points are:
41.059167,77.683333 (me)
41.0181,77.6708 (you)
And our end points are:
36.295364,78.755593 (me)
36.314,78.7654 (you)
Also I calculate the distance assuming the Earth is spherical (which gives 538 km) not the standard geodesic (which would give 537 km).
And in the DEM data I measure the distance from the center of a cell to another (not the edge), while measuring from edge to edge may explain a difference of at most 0.1 km as the DEM resolution is 3 arcseconds.
So clearly we disagree on the coordinates of the exact actual sightline as we have a 7 km difference :-)
Edit #2: clearly the error is on your side. I should have checked this first, but the coordinates you give for the "To" point (41.0181,77.6708) land in a valley with the south view completely blocked so it's impossible to view 500+ km south as you claim. Look at where the marker lands on this Google Maps Terrain: https://maps.app.goo.gl/PgBWxi31WZC6vk3V9
There's two forms of interpolation going on here that I'm not sure you or Dr Dueschle are using. We interpolate a "band of sight" of single a degree for our azithmual projection, but uniquely we also rotate the DEM elevations around all the observers rather than the observer around to see all the elevations.
The effects of the first can be lessened by lowering the band of sight such that we only process half a degree at a time so that we make sure we get more coverage further away. We plan on running some more experiments by rotating to cover more points.
The algorithm is already fairly expensive to run against the whole world so we weren't particularly interested in that level of coverage for the full earth.
For total viewshed area, our algorithm comes in at roughly a percent or so difference which was what we used as our benchmark for correctness.
All this to say, no, we don't think you both are wrong, we've been looking at making ours more accurate. At a world scale that's quite computationally expensive, so we didn't use that methodology for our initial launch. We see our results as validation of yours, not as something we've disproved.
Ok that makes sense, thanks for the reply! Maybe document this "percent or so" error in the FAQ since it is about 16 times bigger than the (other?) ~0.0685% error you mention that can be caused by the AEQD reprojections.
Good idea, I'll add it to the FAQ later today. Under a section of "why don't these results match the other tools". The projection error is separate as you mentioned.
The error I've experienced hunting bugs tends to be within about .5-2%. That's a vibe, not an empirical "I've calculated the error to be 1.5%". We definitely expect that bound to tighten as we get access to more computational resources.
I do not think this is numerical however. I think it's more directly related to rasterization, interpolation, and not enough angle coverage. We have fairly good numerical and viewshed tests to double check we don't have weirdness going on there.
Reply to my edit #2: I realize the "To" point 41.0181,77.6708 is just the coordinate of the center of the 1°-wide horizon line. The actual farthest visible point according to your analysis is probably this peak in the west half of the 1° field of view: 41.014862, 77.647818 So I retract my comment about the error being "clearly" on your side. However this does indicate that we definitely calculate things differently. In my analysis Pik Dankova at 41.059542, 77.684808 which is a few km further can actually be seen and that's the source of our differences. I don't know who is right.
I suppose our hobby is related to the hobby of ground-to-ground long-distance observation. Except we don't perform the actual observation, just the math of where it is theoretically feasible :-) In my case, years ago, I did exactly the same as Tom and Ryan: I algorithmically searched for the longest sightline. It was a weekend project just to satisfy my curiosity. Then last year, Tom and I kinda connected informally over this hobby.
Whenever this discussion comes up I liked to point out that even in the computer industry, prefixes like kilo/mega/etc more often mean a power of 10 than a power of 2:
They almost always mean power of 10, unless you're discussing RAM, RAM addressing, or RAM pages. (or flash, which has inherited most of the same for most of the same reasons)
> The only few places where binary prefixes are used are to refer to RAM capacity and file sizes, whereas decimal prefixes apply to all other areas and all units (not "only bitrates"): storage capacity, clock frequency, stream bandwidth, baud, pixel numbers, data throughput, processing power
Storage capacity also uses binary prefixes. The distinction here isn't that file sizes are reported in binary numbers and storage capacity is reported in decimal numbers. It's that software uses binary numbers and hard drive manufacturers use decimal numbers. You don't see df reporting files in binary units and capacities in decimal units.
Of that large list of measurements, only bandwidth is measured in bytes, making the argument mostly an exercise in sophistry. You can't convince anyone that KB means 1000 bytes by arguing that kHz means 1000 Hz.
Nice page, and nice link to Colin Percival's page too! Let me toss you one example: CDs are marketed in mebibytes. A "650 MB" burnable CD is actually 650 MiB ≈ 682 MB, and likewise for "700 MB" being actually 700 MiB ≈ 734 MB. DVD and BD do use metric prefixes correctly, like you pointed out. Back in the day, I archived my data on CD/DVD/BD, and I planned out my disc burns to have only about 1 to 10 MB of wasted space, so I had to be very aware of the true definition and exactly how much capacity was available for me to use.
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