explain xkcd - User contributions [en]

Talk:3179: Fishing

2025-12-11T19:08:42Z

209.188.63.98:

The tug on a fishing line would be measured in newtons, not kilograms. [[Special:Contributions/76.187.17.7|76.187.17.7]] 04:30, 11 December 2025 (UTC)
: It's at least a C+ [[Special:Contributions/65.35.15.18|65.35.15.18]] 05:12, 11 December 2025 (UTC)
: Yes, but he is not measuring the force, he is measuring the "weight" (mass) of the thing he thinks he hooked. (e.g. a 5 lb fish)[[Special:Contributions/2603:8000:5E00:2913:EE02:2D56:E960:2CDE|2603:8000:5E00:2913:EE02:2D56:E960:2CDE]] 05:21, 11 December 2025 (UTC)

YAY BERET GUY![[User:Mathmaster|Mathmaster]] ([[User talk:Mathmaster|talk]])

Beret Guy's estimate is, of course, absurd (or it would be for anyone else). His lifting capacity, the breaking points of his line and rod, the buoyancy of his boat and the force to break loose an individual piece of rock (the lowest of which would mark the upper bounds for his estimate) are (many) orders of magnitude lower than the force required to haul a 10^24 kg catch into the boat [citation needed, I guess] [[User:627235|627235]] ([[User talk:627235|talk]]) 11:42, 11 December 2025 (UTC)
:He's not saying that he can reel it in, just estimating the size of the "fish" he's hooked. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 14:57, 11 December 2025 (UTC)
:When he pulls, there is a little bit of give (infinitesimal) as the planet moves - he might be sensing that and estimating based on it. Assuming you know the properties of the fishing line, like its stretch, and of the boat's surface area, buoyancy. I don't see why it wouldn't be possible to estimate given perfect knowledge of the water, boat, line, forces, etc, even if the Earth is much more massive than the boat being pulled downwards [[User:R128|R128]] ([[User talk:R128|talk]]) 15:22, 11 December 2025 (UTC)
:At that massive scale, wouldn’t the upper bound of weight he could detect the buoyancy of the boat - beyond that he is no longer pulling anything up, but pulling himself down - so that the resistance he feels is the buoyancy keeping the boat up? [[Special:Contributions/71.17.36.59|71.17.36.59]] 16:18, 11 December 2025 (UTC)

Planets don't have a catch size limit. By definition, a planet has cleared its neighborhood, meaning there's no need to maintain a breeding population. Now, dwarf planets and small solar system bodies are a different story, and the rules are rather strict. [[Special:Contributions/209.188.63.98|209.188.63.98]] 19:08, 11 December 2025 (UTC)

Talk:3174: Bridge Clearance

2025-11-30T05:23:59Z

209.188.63.98:

But when the moon is directly overhead they also have to edit the contents of the sign [[User:Mathmaster|Mathmaster]] ([[User talk:Mathmaster|talk]])
:The Moon being overhead only applies to places in latitudes roughly between 28.5 degrees N and S, at its absolute most extreme inclinations. So, for the contiiguous US, that potentially affects only roads in some bits of Florida and Texas.
:Louisiana's most southern point is ''very'' close to that, such that the 'upper limb' of our satellite would 'overhead' an additional quarter of a degree of latitude, taking in this spot and a bit more. But that location is also an island. {{w|Port Fourchon, Louisiana}}, seems to be the most southerly stretch of regular (mainland) road in that state, and that's still just too far north to be affected. [[Special:Contributions/78.144.255.82|78.144.255.82]] 23:10, 28 November 2025 (UTC)

Note how the second sign extends off the panel, presumably with a warning further up for any vehicles under clearance. That’s quite the space elevator. [[User:KelOfTheStars!|KelOfTheStars!]] ([[User talk:KelOfTheStars!|talk]]) 01:21, 29 November 2025 (UTC)

Also note that in latitudes where the moon could possibly be directly overhead, the sun could also be directly overhead. This would also necessitate a change to the sign [[Special:Contributions/24.210.252.188|24.210.252.188]] 02:56, 29 November 2025 (UTC)
:(Moon tilt on top of Earth tilt makes the all-seasons "Sun overhead" a narrower band than the potential "Moon-overhead", i.e. Tropic Of Capricorn to Tropic Of Cancer).
:For an even greater range, and lower clearance, consider the ISS. Then there's the Starlink/etc constellation 'mesh' of orbits that deliberately stretches further out. Or indeed polar-(/near-polar-)orbits for Earth Observation (Sun-synchronous orbits, slightly off polar, typically can be directly above anything up to 82-ish° N/S, being 98° and retrograde.
:And clearances of GSOs (there will be locations where sufficiently geo''stationary'' satellites are pretty much perpetual, though mere geo''synchronous'' ones may have daily (or twice-daily, on the crux of the figure-of-8 ground track) 'exposure') are so much greater than what the LEO ones would.
:A particular favourite of the Russian civil/military programmes are ''highly'' eccentric (and oblique) to service the kind of latitudes they want more loiter (slow, and far away) ''or'' passage (near, but rapid) over, often in teams of craft spread across the track to pass coverage over to another when one of them zooms on out of the desired 'sweet spot'... "Tundra Orbits", I think it is? So accounting for them might involve vastly varying heights (though usually similar, overhead to overhead, barring any ascending-/descending-track differences) over a greater-than-average spread of latitudes (but still less than pure 90°-polar would, which is potentially over everywhere at some time or another). [[Special:Contributions/82.132.237.174|82.132.237.174]] 14:06, 29 November 2025 (UTC)

When I first read the title text I thought it was talking about the tide's effect on the height of the bridge. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 03:55, 29 November 2025 (UTC)

How old is the sign that needs to he updated every day? These days they have automated signs for things like travel time to important exits, that type of system could easily be used to keep the clearance up-to-date. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 03:59, 29 November 2025 (UTC)
:It'll cost more to at least ''maintain'' a changable sign. Perhaps power connection (unless solar+battery is enough), probably data connection (push- or pull- reconfiguration, unless relying upon continually internally calculated via RTC and the appropriate ephemera). It might not need to be visited each day, but periodic checks are going to be more than checking it hasn't been overly pierced by buckshot (or being told it's been flattened by a carelessly driven vehicle), and other charges will apply. Especially if you're covering every few yards (even hundreds of yards) of road with individually personalised warnings for that particular stretch. [[Special:Contributions/82.132.237.174|82.132.237.174]] 14:06, 29 November 2025 (UTC)

> ''clearance of 10 feet and 6 inches, which is a realistic clearance''..... Anything less than 13'6" (in the US) will get hit frequently. Yes, we know some bridges that get hit frequently. --[[User:PRR|PRR]] ([[User talk:PRR|talk]]) 06:42, 29 November 2025 (UTC)
:: It says realistic, not common. {{w|Storrow Drive}}, which should be very familiar to Randall, has a clearance of just 10 feet. --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 07:08, 29 November 2025 (UTC)
::: Memorial Drive, at the so-called Harvard Bridge, right near MIT, has a clearance of 9 feet 0 inches. Large commercial traffic is not allowed on those two roads. Somehow big trucks go there regardless. MIT students sleeping in the nearby dorm, occasionally awaken to a loud noise. They phone MIT Campus Patrol, say, "Truck trap," and return to slumber. [[Special:Contributions/173.188.194.233|173.188.194.233]] 15:10, 29 November 2025 (UTC)
:: The current standard for bridge heights was established in 1956, when the US Interstate Highway system came into being. The minimum height was originally 14 feet (4.3 m), it was promptly (by 1960) raised to 16 feet (4.9 m); the <del>War</del> Defense Department had demanded 17 feet (5.2 m). Highways built before the Interstate highway system set the standard (such as Storrow Drive, 1950) had lower clearances. The Merritt Parkway in Connecticut, a pioneering controlled-access highway built in the late 1930s, had a minimum bridge height of 11 feet (3.4 m); some of those clearances today are, or approach, 10 feet six inches (3.2 m). Surviving low-clearance bridges tend to be covered bridges over streams, and railway bridges over secondary roads, all built in the 19th and early 20th centuries. Trucks designed specifically (as they were, IIRC) to haul goods over the Interstate system will struggle on these older constructs. [[Special:Contributions/2605:59C8:160:DB08:E8F0:A309:4673:6AEF|2605:59C8:160:DB08:E8F0:A309:4673:6AEF]] 16:04, 29 November 2025 (UTC)
::Plenty of bridges in the UK get Bridge Strikes from trucks (despite copious warnings), and even the occasional double-decker bus that the driver gets wrong (wrong route, perhaps on a Not In Service drive to/from the depot, and forgotten what he's driving, hopefully nobody's riding above). Almost any city (and many rural locations) will probably know at least one local railway (or canal!) bridge that has massive amounts of face-protection (painted with warning stripes, words and height details, all the round warning signs, probably a 'jangly chain-bar' roof scraper and/or photoelectric warning-sign illuminator in the last stretch before it - and ''still'' visible scraping/denting on the add-on face-protection).
::Not sure if it's the lowest, vehiclewise, but for the UK I found https://www.youtube.com/watch?v=Vy9PmSRwG-k (going by the video thumbnail only) as a bridge that (non-SUV!) cars can just about use. But most people couldn't even walk or ride a bike under it, without ducking. Though at least you'd be high enough in any lorry cab to ''know'' it's a barrier to your vehicle. (Well, you'd have missed/disbelieved the signage, but basically be heading at a more obvious 'wall'.) [[Special:Contributions/82.132.237.174|82.132.237.174]] 16:16, 29 November 2025 (UTC)
::: Try [https://www.google.co.uk/maps/@55.9486871,-4.1246238,3a,15y,159.97h,91.04t/data=!3m7!1e1!3m5!1sTzKuejjwGJ6h-bbUb5rVbg!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fcb_client%3Dmaps_sv.tactile%26w%3D900%26h%3D600%26pitch%3D-1.037973936125013%26panoid%3DTzKuejjwGJ6h-bbUb5rVbg%26yaw%3D159.96810709182384!7i13312!8i6656?hl=en&entry=ttu&g_ep=EgoyMDI1MTEyMy4xIKXMDSoASAFQAw%3D%3D this one] in Scotland, at 4 feet 9 inches (3.2 m). [[Special:Contributions/2605:59C8:160:DB08:E8F0:A309:4673:6AEF|2605:59C8:160:DB08:E8F0:A309:4673:6AEF]] 19:48, 29 November 2025 (UTC)
::::I don't know what that sign says, or how smalle Scotttish feet are, but 4`9 is slightly under 1.5m. :D --[[Special:Contributions/88.65.244.212|88.65.244.212]] 22:17, 29 November 2025 (UTC)
::::Depending on which Stretview shots (varied examples, seemingly, by time), you also get it as 4'6" and 1.3m warnings (if exactly that in Ft+In, which it might not be, should basically be 1m 37⅙cm, so probably was rounded down to 1.3m, even if the true value was also rounded down to get 4'6", which is better than being rounded ''up''). The 4'9" might therefore have been a typo/thinko/printo on that version of the non-metric signage, or an inadvertant round-''up'' from the real measurement.
::::It looks like the signs on the bridge itself are accurate enough (in a downward-rounding direction), at least in the various versions I've discerned that are not either blurred by the StreetView process or obscured by the vegetation trailing down from above. [[Special:Contributions/78.144.255.82|78.144.255.82]] 22:52, 29 November 2025 (UTC)
::::: It was 1.4 m, not 3.2. I erred. [[Special:Contributions/205.175.118.102|205.175.118.102]] 00:23, 30 November 2025 (UTC)

Would expect that those in charge of the airspace would object to vehicles passing through. [[Special:Contributions/64.114.211.61|64.114.211.61]] 17:57, 29 November 2025 (UTC)

Hello, If I may, I was thinking that there is an implied sacrificial bar on the ~46b light year sign, as the sign post does not stop at the sign, but continues on out of the panel. This could also add context as to why it is so expensive for the moon to cross over the road, as the highway department would need to very quickly replace the sacrificial bar with a much lower one, only to put the taller one back up a couple minutes or even seconds later. [[User:Nvidietha|Nvidietha]] ([[User talk:Nvidietha|talk]]) 19:04, 29 November 2025 (UTC)

: What would happen to a 45-million light-year bar attached to a rotating surface such as earth? Given that points further from the centre would be rotating quicker, wouldn't the points near the end be at and above the speed of light? Would the act of extending it and expending earth's momentum on rotating it and spend all of the speed which allows the end to approach C? What if it materialised instead of extended? As far as i can tell, the Federal Road Body does not have the budget to break the laws of the universe. [[Special:Contributions/92.40.216.156|92.40.216.156]] 21:25, 29 November 2025 (UTC)
:: Just taking Earth's rotation into account, the tip would be traveling (length of pole)×2pi per day. Assuming I didn't mess up some units with my napkin math, the tip will be going the speed of light at a length of about 25 AU, which is effectively microscopic on any scale worth measuring in light years. [[Special:Contributions/209.188.63.98|209.188.63.98]] 05:23, 30 November 2025 (UTC)

Would the presence of stuff deeper in space like stars and asteroids not warrant a constantly-changing number as the earth rotates such that the road intersects different ones? Currently, if a car with a 10-thousand light-year thing atop following the rotation of earth would likely be constantly hitting various space things as it rotates to follow the earth. [[Special:Contributions/92.40.216.156|92.40.216.156]] 21:17, 29 November 2025 (UTC)
: My thought is that, if one maintains a maximally-strict definition of "directly overhead", the need for such changes would, in actuality, be vanishingly small. Without attempting to crunch numbers, I imagine that, in the context of deep space (and assuming that deep space is finite), a cylinder 2 m in diameter, stretching from the earth's surface, would disappear into the void and hit almost nothing. [[Special:Contributions/205.175.118.102|205.175.118.102]] 22:29, 29 November 2025 (UTC)

Talk:3173: Satellite Imagery

2025-11-27T17:11:44Z

209.188.63.98:

This is another comic in the ''My Hobby'' series, and is also about pranking conspiracy theorists. [[Special:Contributions/2001:4C4E:1C08:2800:DC6F:548F:9B29:AAE1|2001:4C4E:1C08:2800:DC6F:548F:9B29:AAE1]] 21:43, 26 November 2025 (UTC)
:Not pranking conspiracy theorists... Pranking the kind of people that conspiracy theorists theorise about. There's clear indication that they are working for one or other "three letter agency" (or else they'd be directly blaming No Such Agency/whoever, over and above the other explanations they're considering) and are trained and salaried analysts, rather than armchair hobbyists of the more nebulously self-organised and self-motivating kind. [[Special:Contributions/82.132.245.70|82.132.245.70]] 00:12, 27 November 2025 (UTC)

I know there are places (like parts of Oregon) that ''look'' pixelated due to [https://en.wikipedia.org/wiki/Checkerboarding_(land) checkerboarded land ownership]. But something like ''this'' would be next-level! --[[User:Aaron of Mpls|Aaron of Mpls]] ([[User talk:Aaron of Mpls|talk]]) 03:32, 27 November 2025 (UTC)

imagine how much more terrifying it'd be if you did that with the sky :P [[Special:Contributions/176.126.228.189|176.126.228.189]] 08:41, 27 November 2025 (UTC)

If that (original, pre 'censorship tiles') image is not cleverly composited from multiple sources (including perhaps decorated by perlin-noise and/or hue-shifted), it might ''just'' be possible to chase down the actual shot used, with a little dedication. The particular colour of the landscape (being wary of seasonal variation) might tie it down to a subset of semi-arid regions through which rivers are flowing, with a bit of cultural guessing on top.<br/>I'm guessing, from the limited cues (the 'track' footprints, and the natural evolution of the junction curves through continued use of a turnoff) that the 'pixel' tiles are 100-200 yds on-the-ground. There's limited topological information (except for in analysing the fluvial and alluvial vicinities of the riverine cutbanks) but no immediate sign of extreme gradients — only hints that some adjacent dirt-tracks don't connect due to it being less flat/level in places.<br />A practiced jigsaw-doer should be able to scroll across a Google Maps (or other vendor's) photo-overheads and twig when the right sort of features pass by. We're even good at handling orientation differences (the trickiest thing Randall might have done is to rotate his 'piece' arbitrarily, but we've all had to deal with bits of fuzzy cloud/undergrowth/stonework that could be ''any'' way round, when trying to match against the box image — which is additionally faded or otherwise not really properly colour-matched). The difference being that there's no 'giving up on this piece' (maybe no more than a couple of miles square, 'on the ground'), after five or ten minutes, to pass onto the next awkward 'middle of the difficult patch' one to see if you might have slightly better luck in whittling down the unmatched spaces. [[Special:Contributions/82.132.245.70|82.132.245.70]] 16:55, 27 November 2025 (UTC)

The title text reminds me of the Map Men episode in which the existence of the watermark was presented as proof that Google was trying to claim Bir Tawil. [[Special:Contributions/209.188.63.98|209.188.63.98]] 17:11, 27 November 2025 (UTC)