explain xkcd - User contributions [en]

3204: Dinosaurs And Non-Dinosaurs

2026-02-06T21:53:03Z

88.65.244.212: /* Explanation */

{{comic
| number = 3204
| date = February 6, 2026
| title = Dinosaurs And Non-Dinosaurs
| image = dinosaurs_and_non_dinosaurs_2x.png
| imagesize = 370x283px
| noexpand = true
| titletext = Staplers are actually in Pseudosuchia, making them more closely related to crocodiles than to dinosaurs.
}}

==Explanation==
{{incomplete|This page was created by something that doesn’t seem like a dinosaur. Don't remove this notice too soon.}}

This comic explores the seeming paradox that certain extinct prehistoric species which are popularly thought of as being "dinosaurs" are, from a strict taxonomic viewpoint, not. It also takes into account the fact that all bird species are descended from dinosaurs and thus - again, from a strict taxonomic viewpoint - are themselves dinosaurs as well (see [[1211]]). To illustrate this, Randall provides silhouettes of dinosaurs, of entities that are widely thought of as dinosaurs but are not, of entities that are ''not'' widely thought of as dinosaurs but ''are'' (i.e., birds), and, lastly, of entities that are neither dinosaurs nor thought of as dinosaurs (which is funny because it's so all-encompassing, as it would if you replaced the word "dinosaurs" by any other plural noun, or adjective. Always all-encompassing, often not very funny).

Clockwise from upper left in each quadrant of the image:
* Silhouettes in "seem like dinosaurs / are dinosaurs": stegosaurus, triceratops, tyrannosaurus, diplodocus, velociraptor
* Silhouettes in "seem like dinosaurs / are not dinosaurs": mosasaur, quetzalcoatlus, dimetrodon, plesiosaur, pteranodon
* Silhouettes in "don't seem like dinosaurs / are not dinosaurs": squirrel, stapler, bicycle, Cueball, pineapple
* Silhouettes in "don't seem like dinosaurs / are dinosaurs": penguin, egret, falcon, pigeon, ostrich

The title text is a further joke about taxonomy, predicated on the assumption that staplers are biological organisms (which they are not){{citation needed}}, and can thus be sorted into taxa. ''{{w|Pseudosuchia}}'' is in fact the clade that encompasses all crocodilians, and staplers bear a certain resemblance to the open jaw of a crocodilian.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}
:[A 2x2 chart containing various animals and objects.]
* Left column: Are dinosaurs
* Right column: Are not dinosaurs
* Upper row: Seem like dinosaurs
* Lower row: Don't seem like dinosaurs

:[Top left (seem like dinosaurs, are dinosaurs):]
:[Top right (seem like dinosaurs, are not dinosaurs):]
:[Bottom left (don't seem like dinosaurs, are dinosaurs):]
:[Bottom right (don't seem like dinosaurs, are not dinosaurs):]
{{comic discussion}}<noinclude>
[[Category:Dinosaurs]]

3204: Dinosaurs And Non-Dinosaurs

2026-02-06T21:49:47Z

88.65.244.212: /* Explanation */ haha

{{comic
| number = 3204
| date = February 6, 2026
| title = Dinosaurs And Non-Dinosaurs
| image = dinosaurs_and_non_dinosaurs_2x.png
| imagesize = 370x283px
| noexpand = true
| titletext = Staplers are actually in Pseudosuchia, making them more closely related to crocodiles than to dinosaurs.
}}

==Explanation==
{{incomplete|This page was created by something that doesn’t seem like a dinosaur. Don't remove this notice too soon.}}

This comic explores the seeming paradox that certain extinct prehistoric species which are popularly thought of as being "dinosaurs" are, from a strict taxonomic viewpoint, not. It also takes into account the fact that all bird species are descended from dinosaurs and thus - again, from a strict taxonomic viewpoint - are themselves dinosaurs as well (see [[1211]]). To illustrate this, Randall provides silhouettes of dinosaurs, of entities that are widely thought of as dinosaurs but are not, of entities that are ''not'' widely thought of as dinosaurs but ''are'' (i.e., birds), and, lastly, of entities that are neither dinosaurs nor thought of as dinosaurs (which is funny because it's so all-encompassing, as it would if you replaced the word "dinosaurs" by any other plural noun).

Clockwise from upper left in each quadrant of the image:
* Silhouettes in "seem like dinosaurs / are dinosaurs": stegosaurus, triceratops, tyrannosaurus, diplodocus, velociraptor
* Silhouettes in "seem like dinosaurs / are not dinosaurs": mosasaur, quetzalcoatlus, dimetrodon, plesiosaur, pteranodon
* Silhouettes in "don't seem like dinosaurs / are not dinosaurs": squirrel, stapler, bicycle, Cueball, pineapple
* Silhouettes in "don't seem like dinosaurs / are dinosaurs": penguin, egret, falcon, pigeon, ostrich

The title text is a further joke about taxonomy, predicated on the assumption that staplers are biological organisms (which they are not){{citation needed}}, and can thus be sorted into taxa. ''{{w|Pseudosuchia}}'' is in fact the clade that encompasses all crocodilians, and staplers bear a certain resemblance to the open jaw of a crocodilian.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}
:[A 2x2 chart containing various animals and objects.]
* Left column: Are dinosaurs
* Right column: Are not dinosaurs
* Upper row: Seem like dinosaurs
* Lower row: Don't seem like dinosaurs

:[Top left (seem like dinosaurs, are dinosaurs):]
:[Top right (seem like dinosaurs, are not dinosaurs):]
:[Bottom left (don't seem like dinosaurs, are dinosaurs):]
:[Bottom right (don't seem like dinosaurs, are not dinosaurs):]
{{comic discussion}}<noinclude>
[[Category:Dinosaurs]]

Talk:3186: Truly Universal Outlet

2025-12-26T20:24:18Z

88.65.244.212:

No comments yet, add the first comment! [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 16:25, 26 December 2025 (UTC)

I checked on the info.0.json and there doesn't seem to be a transcript for this one. I don't know whether that's normal, since I understand that most comics have one, but I wrote in a basic transcript. I might have just not looked in the right place. [[User:R128|R128]] ([[User talk:R128|talk]]) 16:58, 26 December 2025 (UTC)

I try not to be nationalistic or jingoistic about anything, but I'm sorry—British plugs are simply the best plugs. Strong, easy to use and safe—fits snugly into the socket, can't expose live or neutral outlets without first connecting to earth, no overly sharp pins. I don't like myself for saying this, but I honestly think the rest of the world would be better off switching to our plugs.[[Special:Contributions/109.149.114.159|109.149.114.159]] 18:00, 26 December 2025 (UTC)

:I'm American, and British plugs and sockets seem huge and clunky to me. I've also heard that (some?) Brits think US plugs are alarmingly flimsy. I'm sure that a big part of the differences of opinion is what we grew up with, and I'd love to hear a physics/engineering/UI/UX-based evaluation of which one is *actually* better. -- [[User:Dtgriscom|Dtgriscom]] ([[User talk:Dtgriscom|talk]]) 19:38, 26 December 2025 (UTC)

:: I am an American (soon to be a Gileadian after we will rename our nation to the Republic of Gilead —— ¡ChrisoFascism sucks!); so now I do not have a dog in this fight, but the [http://wikipedia.org/wiki/europlug | EuroPlug ] looks very space efficient, unlike the bulky American plus & sockets, & the ridiculously enormous UK-plugs.

Someone will probably address this, but voltage issues aside, I would guess that the USAGE of the various pins across countries is likely different in catastrophic ways. E.g. I imagine that one glob of pins is hot/live in one country but ground/earth in others so that plugging an appliance from different countries into the universal outlet would cause shocks, breaker trips, explosions, etc. I did laugh at the title text - yes, I'm sure building inspectors are constantly encountering this mess. ;) [[Special:Contributions/47.248.235.170|47.248.235.170]] 18:39, 26 December 2025 (UTC)Pat
:Nope. The ground pin is always intentionally made special in all mains plugs existing, and it's basic potty training for electricians to never, ever trust the two others. --[[Special:Contributions/88.65.244.212|88.65.244.212]] 20:24, 26 December 2025 (UTC)
[https://www.internationalconfig.com/catalog_pages/universal_adapter_page.jpg Universal/travel plug adaptors] do kind of look like this. Not quite as universal though. [[Special:Contributions/220.244.124.170|220.244.124.170]] 19:50, 26 December 2025 (UTC)
:https://www.youtube.com/watch%3Fv%3DAIOqOxI0K_I --[[Special:Contributions/88.65.244.212|88.65.244.212]] 20:24, 26 December 2025 (UTC)

Talk:3182: Telescope Types

2025-12-26T00:42:29Z

88.65.244.212:

no vampire jokes 🥀 ([[1791]]) [[User:TheTrainsKid|TheTrainsKid]] ([[User talk:TheTrainsKid|talk]]) 00:08, 18 December 2025 (UTC)

Got down some preliminary descriptions of each telescope type used [[Special:Contributions/185.132.133.218|185.132.133.218]] 01:44, 18 December 2025 (UTC)

insert that one mickey mouse meme with the caption "what a fucking narcissist"
[[User:Yaokuan ITB|Yaokuan ITB]] ([[User talk:Yaokuan ITB|talk]]) 02:33, 18 December 2025 (UTC)

abnormally low joke-to-real ratio for this format of comic! [[Special:Contributions/2601:241:8002:3E0:C0A2:9DA:ED39:D13F|2601:241:8002:3E0:C0A2:9DA:ED39:D13F]] 03:21, 18 December 2025 (UTC)
:I noticed that... I think this might've originally been 'look at all these cool telescope types', but then he realized he had to put some sort of joke somewhere. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]] 03:27, 18 December 2025 (UTC)

Can someone make a category for The Core (2003)? It's been mentioned often enough. [[Special:Contributions/83.245.251.49|83.245.251.49]] 09:22, 18 December 2025 (UTC)
:Can you list 4 more comics then I will make the category. I think that is about the limit for when to make a new category. I know there are a few more but is it only 2-3more? --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:00, 18 December 2025 (UTC)
::All I can think of is [[673: The Sun]]. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]] 15:09, 18 December 2025 (UTC)
:::Also mentioned in the title text of [[2858: Thanksgiving Arguments]]. --[[Special:Contributions/208.59.176.206|208.59.176.206]] 15:24, 18 December 2025 (UTC)
:: The [[:Category: Th--[[Special:Contributions/88.65.244.212|88.65.244.212]] 00:42, 26 December 2025 (UTC)e Core|The Core]] category was already created, nearly two years ago. This comic is the 7th reference --[[User:Deebster|Deebster]] ([[User talk:Deebster|talk]]) 23:54, 18 December 2025 (UTC)

> This would not […] end well for the drinker.

Would it though? ''Drinking'' elemental mercury, while not great on nutritional value, should be mostly safe (and I'm using that word quite loosely). The most danger would be while drinking and expelling it, when there's a danger of inhaling mercury vapors, right? --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 10:29, 18 December 2025 (UTC)
: ... Agreed. Elemental mercury is dangerous when inhaled, not when drinked. https://en.wikipedia.org/wiki/Mercury_poisoning [[Special:Contributions/109.81.171.81|109.81.171.81]] 21:12, 18 December 2025 (UTC)
:: (it's ''..when drunk.'') ;)
It wouldn't take much work to make the "Real?" column all contain only "yes" [[Special:Contributions/136.32.133.124|136.32.133.124]] 12:05, 18 December 2025 (UTC)

As all others are refractors or reflectors, can cardboard tube be considered a diffractor? As it is the only thing that it does.--[[User:Trimutius|Trimutius]] ([[User talk:Trimutius|talk]]) 15:43, 18 December 2025 (UTC)
:Well, all the others do it as well. Even more so, as they have more objects in the light path. --[[Special:Contributions/88.65.244.212|88.65.244.212]] 00:42, 26 December 2025 (UTC)
> Children may sometimes use tubes [...]

It's not just children. I've seen "viewing tubes" in at least a couple of places, hard-mounted metal tubes that point at particular points of interest. I'm not finding any good references, but here's a photo showing some at the top of a nearby mountain: https://maps.app.goo.gl/wwnYJ1zEQEXzjyJS8 [[User:Jordan Brown|Jordan Brown]] ([[User talk:Jordan Brown|talk]]) 18:07, 18 December 2025 (UTC)

Is the joke with "Geological" that it's looking at something 'far away' from actual Geology? {{unsigned ip|64.203.66.182|17:14, 19 December 2025}}

Talk:3182: Telescope Types

2025-12-26T00:40:02Z

88.65.244.212: grammar nazi comment

no vampire jokes 🥀 ([[1791]]) [[User:TheTrainsKid|TheTrainsKid]] ([[User talk:TheTrainsKid|talk]]) 00:08, 18 December 2025 (UTC)

Got down some preliminary descriptions of each telescope type used [[Special:Contributions/185.132.133.218|185.132.133.218]] 01:44, 18 December 2025 (UTC)

insert that one mickey mouse meme with the caption "what a fucking narcissist"
[[User:Yaokuan ITB|Yaokuan ITB]] ([[User talk:Yaokuan ITB|talk]]) 02:33, 18 December 2025 (UTC)

abnormally low joke-to-real ratio for this format of comic! [[Special:Contributions/2601:241:8002:3E0:C0A2:9DA:ED39:D13F|2601:241:8002:3E0:C0A2:9DA:ED39:D13F]] 03:21, 18 December 2025 (UTC)
:I noticed that... I think this might've originally been 'look at all these cool telescope types', but then he realized he had to put some sort of joke somewhere. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]] 03:27, 18 December 2025 (UTC)

Can someone make a category for The Core (2003)? It's been mentioned often enough. [[Special:Contributions/83.245.251.49|83.245.251.49]] 09:22, 18 December 2025 (UTC)
:Can you list 4 more comics then I will make the category. I think that is about the limit for when to make a new category. I know there are a few more but is it only 2-3more? --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:00, 18 December 2025 (UTC)
::All I can think of is [[673: The Sun]]. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]] 15:09, 18 December 2025 (UTC)
:::Also mentioned in the title text of [[2858: Thanksgiving Arguments]]. --[[Special:Contributions/208.59.176.206|208.59.176.206]] 15:24, 18 December 2025 (UTC)
:: The [[:Category: The Core|The Core]] category was already created, nearly two years ago. This comic is the 7th reference --[[User:Deebster|Deebster]] ([[User talk:Deebster|talk]]) 23:54, 18 December 2025 (UTC)

> This would not […] end well for the drinker.

Would it though? ''Drinking'' elemental mercury, while not great on nutritional value, should be mostly safe (and I'm using that word quite loosely). The most danger would be while drinking and expelling it, when there's a danger of inhaling mercury vapors, right? --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 10:29, 18 December 2025 (UTC)
: ... Agreed. Elemental mercury is dangerous when inhaled, not when drinked. https://en.wikipedia.org/wiki/Mercury_poisoning [[Special:Contributions/109.81.171.81|109.81.171.81]] 21:12, 18 December 2025 (UTC)
:: (it's ''..when drunk.''
It wouldn't take much work to make the "Real?" column all contain only "yes" [[Special:Contributions/136.32.133.124|136.32.133.124]] 12:05, 18 December 2025 (UTC)

As all others are refractors or reflectors, can cardboard tube be considered a diffractor? As it is the only thing that it does.--[[User:Trimutius|Trimutius]] ([[User talk:Trimutius|talk]]) 15:43, 18 December 2025 (UTC)

> Children may sometimes use tubes [...]

It's not just children. I've seen "viewing tubes" in at least a couple of places, hard-mounted metal tubes that point at particular points of interest. I'm not finding any good references, but here's a photo showing some at the top of a nearby mountain: https://maps.app.goo.gl/wwnYJ1zEQEXzjyJS8 [[User:Jordan Brown|Jordan Brown]] ([[User talk:Jordan Brown|talk]]) 18:07, 18 December 2025 (UTC)

Is the joke with "Geological" that it's looking at something 'far away' from actual Geology? {{unsigned ip|64.203.66.182|17:14, 19 December 2025}}

Talk:3179: Fishing

2025-12-12T20:18:15Z

88.65.244.212:

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)
::[[123:_Centrifugal_Force]] --[[Special:Contributions/88.65.244.212|88.65.244.212]] 20:18, 12 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)
:You have to have a 'feel' for the potential elongation of the line (which depends a bit upon knowing how much you've deployed), the properties of the rod and (at least for fish, which weigh 'nothing', when they wish to be neutrally buoyant, but have a muscle-related resistive power and a degree of swim-bladder 'weight adjustment) the pseudo-weight that a given size of likely catch (of a likely species) fights against your line-tug with. You can get fooled that a static-snag is actively fighting you if you think you're ''only'' dealing with a fairly shallow fish when you've managed to snag onto something somewhat deeper so that the resonance of your attempts to pull give you the feeling of a reaction that's more just some kind of Young's Modulus/Hooke's Law artefact. It all feels completely different from a fish finally wrested entirely out of the water, and even allows a catch that's heavier than the eventual breaking-stress of your line (or weight+its effort to be greater than that) to be gradually played towards you while in the water, tiring it and bringing it into reach of your grasp/catch-net that will do the actual work of landing it.
:Though, in this case, I think that Beret Guy ''knows'' how much line he is using/etc, and that he's hooked a planet (however that feels) rather than a more actively resisting (and tiring) seacreature. But by the ''very subtle'' reaction of the body to 'test tugs' (accounting for how this also moves the boat) he has correctly (within an order of magnitude!) assessed its 'dry mass'.
:(A cynic might ask what ''other'' masses he might have caught, between Earth-sized and the next most massive mass that's hookable in this manner... a large part of the Titanic..? Having established that it 'tugs back' more than the latter, then Earth would be the only logical target to lead to such a 'logical guess' of mass. Though even establishing that it isn't a massive shipwreck probably needs extremely well tuned supersenses to rule out. So we can probably still consider it a preternatural Skill Of Beret Guy, even to do that.) [[Special:Contributions/78.144.255.82|78.144.255.82]] 19:56, 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)
:I don't know whether you're ''supposed'' to throw planets back, if they're too small, but everybody knows that ''nobody tosses a dwarf''... [[Special:Contributions/78.144.255.82|78.144.255.82]] 22:11, 11 December 2025 (UTC)
:: Throwing planets back can have catastrophic effects on the local neighbourhood if you're not very careful about ''how'' you throw them back. [[Special:Contributions/82.13.184.33|82.13.184.33]] 09:40, 12 December 2025 (UTC)

Beret Guy is surprisingly inaccurate on this one. You'd need to divide the actual weight of Earth by 6 to his estimated weight. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]] 19:23, 11 December 2025 (UTC)
: I was wondering about that, and at first considered that he was either only referring to the mass of the Earth's crust (two orders of magnitude lighter), or including the mantle (factor or 4 heavier). Both options are way off. It's probably just a Fermi estimate. [[Special:Contributions/2A02:590:1200:E001:EC09:A5D:4C27:42F3|2A02:590:1200:E001:EC09:A5D:4C27:42F3]] 21:32, 11 December 2025 (UTC)
: He did say it was *at least* 10^24, which is not wrong... But you're right, he is off by quite a bit. [[User:R128|R128]] ([[User talk:R128|talk]]) 13:44, 12 December 2025 (UTC)
:: I'd like to see you do any better. ;) [[Special:Contributions/78.144.255.82|78.144.255.82]] 19:31, 12 December 2025 (UTC)
::: Just gave a rock a tug. Feels like six trillion trillion kilos, roughly. lmao [[User:R128|R128]] ([[User talk:R128|talk]]) 20:03, 12 December 2025 (UTC)

Any reason to believe this is an ocean instead of a lake? I changed the transcript to make it more generic, but like "seafloor" better than "bottom," so would change it back if there is some reason to know it is an ocean. [[User:Bobthegoat123|Bobthegoat123]] ([[User talk:Bobthegoat123|talk]]) 19:48, 11 December 2025 (UTC)

Has anyone considered that Beret Guy might be fishing on a different PLANET entirely? That would the explain the different mass he found. [[Special:Contributions/47.152.132.12|47.152.132.12]] 19:03, 12 December 2025 (UTC)
:What different mass? "At least 1024 kilograms" is pretty darn close. ''And'' not even slightly excessive. Seems like a (very) good estimate of the Earth's mass to me. [[Special:Contributions/78.144.255.82|78.144.255.82]] 19:29, 12 December 2025 (UTC)

Talk:3174: Bridge Clearance

2025-11-29T22:17:05Z

88.65.244.212: wrong dimension

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)

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)

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)