explain xkcd - User contributions [en]

3135: Sea Level

2025-09-02T08:52:11Z

Ozymandias:

{{comic
| number = 3135
| date = August 29, 2025
| title = Sea Level
| image = sea_level_2x.png
| imagesize = 321x453px
| noexpand = true
| titletext = They're up there with coral islands, lightning, and caterpillars turning into butterflies.
}}

==Explanation==
{{incomplete|This page was created by A FRIENDLY TIDAL WAVE. Don't remove this notice too soon.}}
In this comic [[Cueball]] is wondering aloud what happened to an island, possibly a {{w|sandbar}} that was visible earlier, but is not anymore. [[Megan]] explains to him that the {{w|tide}} has gone up, and thus the island is underwater. She then tells him about what causes tides, namely the {{w|Moon}}, which is large enough and orbits close enough to Earth to gravitationally affect the waters of our oceans, causing them to go up and down daily. Similarly to [[2809: Moon]], Cueball is amazed at the oddity of our planet having a natural satellite large enough to affect our oceans, and Randall seems to be as well, as the caption says that if the Moon didn't exist, it would sound extremely outlandish and sci-fi-like.

The way Megan phrased the last sentence, that the Moon orbits close to the surface of the Earth could also add to Cueball's outburst. Whereas the Moon is comparatively close to Earth in the solar system, not many people would describe the Moon as being close to the Earth's surface. Especially when they actually find out how far it is away from Earth. Most pictures depicting both the Earth and the Moon simultaneously cheat to make it possible to see them near each other, while still being able to see surface features. If the system is seen from the side, with the Moon and Earth furthest from each other, a picture shown on a computer screen would make both of them rather small. (If [https://youtu.be/Bz9D6xba9Og Earth is a basketball and the moon a baseball], the baseball should be placed around 8 meters from the basketball to represent the correct distance.)

{{w|Tide|Tides}} on Earth would indeed seem strange and unusual to a visitor from almost anywhere else in the universe, along with other features such as the large expanses of liquid water and the oxygen-rich atmosphere that was created by biological activity (photosynthesis). Not to mention the biological activity. As stated in the comic, tides on Earth are largely the result of a single large moon (''the'' Moon) orbiting the Earth at a relatively short distance. This configuration is {{w|List_of_natural_satellites|unique within our solar system}}: Mercury and Venus have no moons, Mars (smaller than Earth) has two (far, far smaller) moons, and each of the remaining planets have several, but are comparatively insignificant, individually. There are four moons in the solar system bigger than the Moon, and a few more almost as big, but they all orbit gaseous planets much larger than Earth, amongst many other minor moons, and thus have far less practical tidal influence upon their respective parent planets. The ''twelfth'' largest known moon is Charon, 12.2% the mass of the dwarf planet Pluto, that it it orbits. (The Moon has 1.2% the mass of Earth, by far the largest such ratio amongst the fully-fledged planetary moons, and is also about 20 times further away in comparison). Its much larger tidal effect has actually resulted in mutual {{w|tidal locking}} so that Charon now orbits only above the same part of Pluto and could not create Earth-like tide cycles. That is, even ''if'' there were plutonian seas quite like ours, another required feature that is effectively unique to the Earth-Moon scenario.

The Sun also influences Earth's tide, as might be expected. If the Moon were absent from Earth orbit, however, tidal amplitudes would be about a third of their current values. The Sun's gravity has about half the influence on Earth's liquid water masses than the Moon does, as the relative distances involved mean that the solar gravity gradient across different parts of the Earth and its oceans is far less. Also, if more than one moon were present, the moon(s) present had much less mass ''or'' the moon(s) present had more distant orbits, tides would have less amplitude. And, in the case of there being multiple moons, they would have much more complex (and possibly difficult to predict) periodicity. If the multiple moons had {{w|orbital resonance}}, the periodicity would be relatively straightforward.

The overall effect of the Moon-dominated tides is that in marginally more than every 6.2 hours (at least for an ocean-dominated equatorial island, such as the comic appears to depict) something that was originally fully revealed by a retreating tide could now be covered be the next rising one. This effect is even more pronounced every 14.75 days, as the Moon and Sun act together to create even higher high tides and lower low tides. Anyone used to the behaviour of the sea would probably be unsurprised by this, but someone normally resident more inland can quite easily be caught out, potentially arriving somewhere by the coast in the morning, to witness the sight of particularly low water levels, then by noon/early-afternoon finding that the seascape has changed and high-water has been reached.

The title text mentions other elements of life on Earth, saying they also seem as outlandish as tides, including {{w|coral islands}}, islands that build up from the skeletons or secretions of small animals, {{w|lightning}}, when electrical discharge creates bright light in the atmosphere, and the {{w|metamorphosis}} of {{w|butterflies}}, when caterpillars create a chrysalis and come out as butterflies.

Lightning is an element of life on Earth since it is thought to have produced chemicals which were important to life's origins. Ozone, produced by lightning, reduces the ultra-violet light reaching earths surface. This protection may have made it easier for life to transition out of the water. Microscopic life in the atmosphere (the aerobiome) affects cloud formation and weather, for instance, some bacteria promote the formation of ice crystals which contributes to rain. As such, the aerobiome may also affect lightning. Lightning is probably a common planetary phenomenon; within our solar system, it [https://science.nasa.gov/science-research/planetary-science/lightning-across-the-solar-system/ occurs on Jupiter, Saturn], and probably Uranus and Neptune. On Mars, lightning probably is generated by electric discharge in dust clouds. The evidence about possible lightning on Venus is mixed.

==Transcript==

:[Single frame, with Megan and Cueball standing at a coastline with grass, with water and waves visible. They are looking at the ocean and are standing together.]

:Cueball: Hey, where's that big island we were looking at this morning?
:Megan: Oh, it's underwater. The ocean's depth here goes up and down by like ten feet every day.
:Cueball: What?
:Megan: It's because the planet has a big moon orbiting near the surface. It causes weird gravity effects.
:Cueball: '''''What???'''''

:[Caption below the frame:]
:People here are used to them, but tides are one of the weirdest and most sci-fi elements of life on Earth.

{{comic discussion}}<noinclude>
[[Category: Comics featuring Cueball]]
[[Category: Comics featuring Megan]]
[[Category: Astronomy]]

3072: Stargazing 4

2025-04-05T09:55:27Z

Ozymandias: Several grammatical changes and changes to tone and wording

{{comic
| number = 3072
| date = April 4, 2025
| title = Stargazing 4
| image = stargazing_4_2x.png
| imagesize = 740x386px
| noexpand = true
| titletext = We haven't actually seen a star fall in since we invented telescopes, but I have a list of ones I'm really hoping are next.
}}

==Explanation==
{{incomplete|Created by a BOT DISTRACTED BY STARS - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
This is the fourth comic in the [[:Category:Stargazing|Stargazing]] series, and it followed [[2274: Stargazing 3]] that came out five years before. That was the longest stretch between two comics in the series so far.

The host [[Megan]] starts off the introduction saying that rude {{w|Yelp}} reviews of the stargazing lesson regard her as not a qualified astronomer due to how simplistic her lessons are and that she is actually just saying the words that come to mind.

Then she states that there are over 20 stars in the sky and some of them are over the age of 100. While this is true, it is an extreme underestimation of their number and age, which respectively number in the thousands (for visible stars) and billions or millions of years. Though in a city there could be less than 20 stars visible even in a clear night, in a normal stargazing session, the event should though be moved to a place with as little light pollution as possible. Although, given the unprofessional nature of Megan's lessons, there is no guarantee that it does not take place in a city.

Megan continues to state true facts that are of no value. She states that our galaxy is huge and that there are more grains of sand in the {{w|Milky Way}} than grains of sand on all of Earths beaches. Since the Earth's sand is a subset of all of the galaxy's sand, and there are more planets with sand other than Earth (such as Mars), there are unquestionably more grains of sand in the entirety of the Milky Way than on Earth. This is a parody of the common saying that there are more stars in the visible universe than grains of sand on all the beaches of Earth. Tangentially it is actually unclear as to whether the star outnumber Earth's sands, as shown here: [https://www.scientificamerican.com/article/do-stars-outnumber-the-sands-of-earths-beaches/ Do Stars Outnumber the Sands of Earth’s Beaches?] and here: [https://www.astronomy.com/science/the-ever-lasting-question-more-sand-or-stars/ The ever-lasting question: more sand or stars?]. Original quote was also all the sand on Earth not just on the beaches.

Megan also adds a helpful hint to those that do not know what a beach is, calling a beach a big wet sandbox.

She then finishes the lesson by correctly saying that there is a black hole in the center of our galaxy ({{w|Sagittarius A*}}), and that stars sometimes fall in and get consumed by the black hole. When stars come too close to black holes, they experience a {{w|tidal disruption event}} (TDE), where a star is pulled apart by the black hole after exceeding its {{w|Roche limit}}. This creates streams of material that orbits the black hole and forms an accretion disk, that will eventually be consumed by the black hole or ejected in jets.

She adds her personal opinion on this fact saying that such events are "hilarious" and proceeds by saying that it's okay to laugh at the fate of those stars as the gravity of the black hole will prevent any signals from those start escaping. This is due to black holes immense gravitational attraction that prevents even light from escaping. In Megan's case the most important consequence of this fact is that any one on planets around such stars, cannot leave Yelp reviews if they hear her laughing. Thus, they cannot add to those that mock her lesson.

However, as the Roche limit of a black hole is always greater than its {{w|Schwarzschild radius}}, reviews made just after the star begins spaghettification could still escape the black hole. Not only do stars not use any kind of human-made technology,{{citation needed}} but any information regarding the app Yelp has yet to reach any star near Sagittarius A*, and will only reach it in 27 thousand years. It could, however, be the civilization on one of the stars planets that would try to leave a comment on Yelp, not the star it self. But the same issues with distances would of course apply. It also seems unlikely that any planet would still be following a star when it first gets that close to a super massive black hole.

In the title text Megan claims that we haven't actually seen a star fall into the black hole since we invented telescopes. This is false as over a hundred TDEs have been discovered in a variety of wavelengths, including by the Hubble telescope. Megan also apparently has a list of stars she would want to see fall into the black hole. But she can keep hoping as humans at this time has no way of changing the orbit of any star, so unless she specifically hopes for some of the closest stars to the black hole falls in next, she is not likely to experience and succes based on her list. But it is a dark wish to have, that certain stars should fall in to a black hole. They might have planets with life on them, that would thus also be destroyed.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Everything is black, Megan is in front of three others, Cueball and Ponytail to the left, and White Hat to the right.]

:[Megan:] Welcome back to stargazing.
:[Megan:] According to some ''incredibly'' rude yelp reviews, I'm "not informative" and "can't possibly be an astronomer" and "just kind of say words as they occur to me."
:[Megan:] I guess some losers just hate cool space facts.

:[The sky is white, the floor is black, Megan is pointing at the sky, while six other characters stand beside her.]

:[Megan:] Anyway, that dot is a "star."
:[Megan:] There are over 20 stars in the sky, and some of them are more than 100 years old.

:[Everything is black again, only Megan is visible.]

:[Megan:] Our galaxy is huge.
:[Megan:] You know the beach? That big wet sandbox?
:[Megan:] Well, there are more grains of sand in the milky way than in all earth's beaches combined.

:[Character off-panel to the left:] Wow.
:[A different character off-panel to the right:] ...Wait.

:[Everything is black again, Ponytail is left of Megan, White Hat and hairbun on the right.]
:[Megan:] The galaxy has a black hole at the center.
:[Megan:] Sometimes stars fall in, which is ''hilarious''.
:[Megan:] Don't worry, it's okay to laugh. The gravity prevents signals from escaping, so they can't leave yelp reviews.

{{comic discussion}}

[[Category:Astronomy]]
[[Category:Space]]
[[Category:Stargazing]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Danish]]
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Hairbun]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring White Hat]]
[[Category:Comics with inverted brightness]]

Talk:3070: Orogeny

2025-04-01T09:41:12Z

Ozymandias:

If only "plutonic" meant "made with real plutonium," sigh. [[Special:Contributions/172.71.167.26|172.71.167.26]] 02:53, 1 April 2025 (UTC)

xkcd. When technical issues interfer with reality correct the technical issues. That's usually easier than changing reality. Sure, the techs will say it's impossible and may even think they are correct but ... [[Special:Contributions/172.71.194.216|172.71.194.216]] 02:55, 1 April 2025 (UTC)

Hey this isn't an interactive april fools comic [[Special:Contributions/162.158.174.225|162.158.174.225]] 04:06, 1 April 2025 (UTC)

Gonna need a new category tag for Geology + Real Estate/Home Ownership comics at this point - this is the 4th I believe. [[Special:Contributions/172.71.255.133|172.71.255.133]] 04:29, 1 April 2025 (UTC)
:I think that's [[:Category:Home Inspections]] -- [[User:Ken g6|Ken g6]] ([[User talk:Ken g6|talk]]) 05:47, 1 April 2025 (UTC)

Is it possible the next comic will be an April Fools'? [[User:Ozymandias|Ozymandias]] ([[User talk:Ozymandias|talk]])

I don't understand the part about ancient collision ... what is meant here? Did tectonic plates come from interstellar events? [[Special:Contributions/172.68.54.68|172.68.54.68]] 09:34, 1 April 2025 (UTC)

Ancient collision refers to tectonic plates colliding millions of years ago.[[User:Ozymandias|Ozymandias]] ([[User talk:Ozymandias|talk]])

Talk:3070: Orogeny

2025-04-01T07:21:36Z

Ozymandias:

3070: Orogeny

2025-04-01T07:20:05Z

Ozymandias: /* Explanation */

{{comic
| number = 3070
| date = March 31, 2025
| title = Orogeny
| image = orogeny_2x.png
| imagesize = 740x303px
| noexpand = true
| titletext = Most properties can only boast INDOOR heated floors.
}}

==Explanation==
{{incomplete|Created by a OUTDOOR HEATED FLOOR - Needs someone who knows geology to add stuff. Do NOT delete this tag too soon.}}

This comic is about an {{w|orogeny}}, the creation of mountain ranges at convergent plate boundaries. The mountain range that Ponytail and Cueball are looking at was formed a billion years ago, but the mountains themselves have been eroded away and replaced. This could reference the Theseus’ Ship thought experiment. Ponytail changed this into a business opportunity.

The title text talks about how magma is technically a heated floor. While most houses only have indoor heated floors, the volcanic seamounts can heat the ground outside.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball and Ponytail are standing together on a mountain and look out at a mountain range.]
:Cueball: I hear these mountains are a billion years old.
:Ponytail: Well, sort of.
:Ponytail: An ancient collision created the mountain belt, but the actual rock layers have been continually uplifted and eroded away.
:Cueball: So it's an old mountain range, but it's been fully renovated?
:Ponytail: Yessir, torn down to the roots. This is good solid plutonic bedrock, freshly uplifted. Great value.
:Ponytail: You in the market?
:Cueball: I dunno, I was looking for new construction. You got any emerging volcanic seamounts?
:Ponytail: Nah, that market is a little too hot right now.

{{comic discussion}}

[[Category:Home Inspections]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Geology]]

3070: Orogeny

2025-04-01T07:19:40Z

Ozymandias: I added a short explaination of what orogeny is and changed "Theseus' Galleon" to "Theseus' Ship" which I believe is more common.

{{comic
| number = 3070
| date = March 31, 2025
| title = Orogeny
| image = orogeny_2x.png
| imagesize = 740x303px
| noexpand = true
| titletext = Most properties can only boast INDOOR heated floors.
}}

==Explanation==
{{incomplete|Created by a OUTDOOR HEATED FLOOR - Needs someone who knows geology to add stuff. Do NOT delete this tag too soon.}}

This comic is about an {{w|orogeny}}, the creation of mountains at convergent plate boundaries. The mountain range that Ponytail and Cueball are looking at was formed a billion years ago, but the mountains themselves have been eroded away and replaced. This could reference the Theseus’ Ship thought experiment. Ponytail changed this into a business opportunity.

The title text talks about how magma is technically a heated floor. While most houses only have indoor heated floors, the volcanic seamounts can heat the ground outside.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball and Ponytail are standing together on a mountain and look out at a mountain range.]
:Cueball: I hear these mountains are a billion years old.
:Ponytail: Well, sort of.
:Ponytail: An ancient collision created the mountain belt, but the actual rock layers have been continually uplifted and eroded away.
:Cueball: So it's an old mountain range, but it's been fully renovated?
:Ponytail: Yessir, torn down to the roots. This is good solid plutonic bedrock, freshly uplifted. Great value.
:Ponytail: You in the market?
:Cueball: I dunno, I was looking for new construction. You got any emerging volcanic seamounts?
:Ponytail: Nah, that market is a little too hot right now.

{{comic discussion}}

[[Category:Home Inspections]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Geology]]

Talk:3067: SawStart

2025-03-27T09:57:05Z

Ozymandias:

It's weird seeing a totally empty explanation, also whats the point of sawstop, don't they just use vibrating blades? [[Special:Contributions/104.23.190.110|104.23.190.110]] 12:40, 24 March 2025 (UTC)
:SawStop is for rotating blades, like you would use for sawing wood. I'm sure there's a good reason why they don't use vibrating blades there, the most likely is "wood is harder than a plaster cast". I could also imagine that vibrating blades don't create nice cuts, which doesn't matter with a plaster cast that will be disposed of, but very much matters with wood used for construction. --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 13:16, 24 March 2025 (UTC)
::Oscillating saws for cutting wood exist, and you could use one to make a long cut, but traditional circular saws are much faster and make straighter cuts. [[Special:Contributions/172.68.234.66|172.68.234.66]] 20:55, 26 March 2025 (UTC)

empty explanation is freaky woah [[Special:Contributions/172.69.194.204|172.69.194.204]] 12:42, 24 March 2025 (UTC)
:Every explanation is empty, at least for a short amount of time. And this is not the earliest that a comic went up (shortly after midday, UK time, when it's not unknown for them to not arrive until after the midnight at the end of the designated publication day), but it looks like you (both, including first-poster at the top) have had the good luck/fortune to be just casually checking for new changes to old articles on the site and instead get 'first look' at the newest addition to it. Of course, it'll be a few hours before most of the article gets fine-tuned into some form of 'completion'. [[Special:Contributions/172.70.86.157|172.70.86.157]] 13:23, 24 March 2025 (UTC)
sudo systemctl stop saw-start.service [[Special:Contributions/172.69.208.132|172.69.208.132]] 13:11, 24 March 2025 (UTC)
:yay you saved the world! --[[User:Bb777|hi]] ([[User talk:Bb777|talk]]) 14:08, 24 March 2025 (UTC)
:"Failed to stop saw-start.service: Access restricted by systemd security policies"
:sudo holding-in-the-power-button doesn't work either.[[Special:Contributions/172.69.34.139|172.69.34.139]] 17:26, 24 March 2025 (UTC)

I'm 99% sure that the system is designed to start a ''stopped'' blade up to full speed within milliseconds, not just increase the speed of a spinning blade. --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 13:22, 24 March 2025 (UTC)

WAITER, WAITER, MORE [[Black Hat]] PLEASE [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 13:31, 24 March 2025 (UTC)

Because of gyroscopic precession, a still spinning (unstoppable?) blade, removed from its axle and housing, would be /very/ difficult and dangerous to dispose of. I'm a woodworker and I think I'll be having nightmares tonight.
-DW [[Special:Contributions/172.69.23.176|172.69.23.176]] 13:36, 24 March 2025 (UTC)
: At least if it's unstoppable we can use it as a free source of energy! [[Special:Contributions/172.69.195.62|172.69.195.62]] 14:01, 24 March 2025 (UTC)

As a woodworker, one note I would like to make is that while the sawblade ''can'' be damaged by cartridge activation, it is not ''required'' that it be replaced. It is possible to have the blade inspected and potentially repaired and continue to use it. That is addressed in SawStop's FAQ https://www.sawstop.com/sawstop_faq/can-the-blade-be-reused-if-the-safety-system-brake-is-activated/ [[Special:Contributions/172.69.33.189|172.69.33.189]] 15:04, 24 March 2025 (UTC)

The [citation needed] for violating other laws probably means that law enforcement should issue a citation to the manufacturer. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 15:21, 24 March 2025 (UTC)

General observation from a s/w test engineer/woodworker: Original version of the Sawstop used a shotgun shell to fire a stopper into the sawblade which absolutely did destroy the blade. (and made enough noise to pretty much ensure a 'code brown' if you triggered the stop system.) Newer version uses a high tension spring along with a deformable aluminum stopper assembly to absorb the energy and bring the blade to a stop. The advantage of the deformable aluminum assembly is that you can remove it from the blade (with care) and as noted can put the sawblade back to work. However you need a new ($200-ish) stopper assembly before you can re-start the saw. Having a family member who is a retired emergency room doctor who would regularly email me 'stories from work' of woodworker injuries who came through her ER, I can assure you that a tablesaw is pretty much the most dangerous woodworking tool in a typical woodshop. That being said, its quite amusing to me that "SawStop" became XKCD worthy. SawStop is somewhat notorious in the woodworking community because of their highly obnoxious business practices with regards patent and legal attacks on business competitors who came up with alternative approaches to the 'saw brake' or 'saw safety' system. JC from Canada {{unsigned ip|172.69.33.194}}
: Funny, the version I'd heard from the woodworking community was SawStop getting vast pushback from their competitors who didn't want to licence the first saw safety systems, and then spent a vast amount of money making their own inferior systems when Sawstop pushed for tablesaws to have to have some sort of safety system. But I suppose it's all a matter of which set of propaganda from the businesses you're buying into. [[Special:Contributions/172.69.195.180|172.69.195.180]] 11:18, 25 March 2025 (UTC)
: The full story is a bit of both. The inventor didn't want to be a table saw company, so he initially tried to license it to existing companies, and only founded SawStop after getting rejected everywhere. Later, Bosch made a similar but distinct system and SawStop sued to keep it from reaching market. Finally, SawStop tried to get the US gov't to make skin-sensing tech mandatory on all table saws, and talked about how they are just trying to be safe, while simultaneously filing a lawsuit against Felder for their newer technology. A lot of people in the community viewed that as hypocritical as they seem to want safety, but only if they are the ones to profit from it. [[Special:Contributions/172.70.94.34|172.70.94.34]] 20:55, 26 March 2025 (UTC)

Funnily enough this could be practical in robot combat [[Special:Contributions/104.23.190.15|104.23.190.15]]15:01, 24 March 2025 EST

Note that since the blade is spun up using explosives and not the electric motor (even ignoring the title text), the saw being unplugged in no way makes the blade safe to touch. [[Special:Contributions/172.68.23.226|172.68.23.226]] 20:03, 24 March 2025 (UTC)

The explosive charge would already be deadly. --[[User:Bb777|[insert signature here]]] ([[User talk:Bb777|talk]]) 00:31, 25 March 2025 (UTC)

:As far as I can tell, this fact has not been included. Nor was it ever there in the last handful of edits (or in what I knew was there beforehand).
:There ''is'' something about Warhammer 40K (which I appreciate the meaning of, but find a little out of the blue as currently written). Maybe you mean that. It could be rewritten as a "in a circumstance such as the world of Warhammer 40K", I suppose. Though why single that out? For reference, though, in case you want to change things: https://warhammer40k.fandom.com/wiki/Chainsword [[Special:Contributions/172.69.43.240|172.69.43.240]] 11:45, 25 March 2025 (UTC)

Talk:3067: SawStart

2025-03-25T09:31:20Z

Ozymandias:

It's weird seeing a totally empty explanation, also whats the point of sawstop, don't they just use vibrating blades? [[Special:Contributions/104.23.190.110|104.23.190.110]] 12:40, 24 March 2025 (UTC)
:SawStop is for rotating blades, like you would use for sawing wood. I'm sure there's a good reason why they don't use vibrating blades there, the most likely is "wood is harder than a plaster cast". I could also imagine that vibrating blades don't create nice cuts, which doesn't matter with a plaster cast that will be disposed of, but very much matters with wood used for construction. --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 13:16, 24 March 2025 (UTC)

empty explanation is freaky woah [[Special:Contributions/172.69.194.204|172.69.194.204]] 12:42, 24 March 2025 (UTC)
:Every explanation is empty, at least for a short amount of time. And this is not the earliest that a comic went up (shortly after midday, UK time, when it's not unknown for them to not arrive until after the midnight at the end of the designated publication day), but it looks like you (both, including first-poster at the top) have had the good luck/fortune to be just casually checking for new changes to old articles on the site and instead get 'first look' at the newest addition to it. Of course, it'll be a few hours before most of the article gets fine-tuned into some form of 'completion'. [[Special:Contributions/172.70.86.157|172.70.86.157]] 13:23, 24 March 2025 (UTC)
sudo systemctl stop saw-start.service [[Special:Contributions/172.69.208.132|172.69.208.132]] 13:11, 24 March 2025 (UTC)
:yay you saved the world! --[[User:Bb777|hi]] ([[User talk:Bb777|talk]]) 14:08, 24 March 2025 (UTC)
:"Failed to stop saw-start.service: Access restricted by systemd security policies"

:sudo holding-in-the-power-button doesn't work either.[[Special:Contributions/172.69.34.139|172.69.34.139]] 17:26, 24 March 2025 (UTC)

I'm 99% sure that the system is designed to start a ''stopped'' blade up to full speed within milliseconds, not just increase the speed of a spinning blade. --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 13:22, 24 March 2025 (UTC)

WAITER, WAITER, MORE [[Black Hat]] PLEASE [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 13:31, 24 March 2025 (UTC)

Because of gyroscopic precession, a still spinning (unstoppable?) blade, removed from its axle and housing, would be /very/ difficult and dangerous to dispose of. I'm a woodworker and I think I'll be having nightmares tonight.
-DW [[Special:Contributions/172.69.23.176|172.69.23.176]] 13:36, 24 March 2025 (UTC)

: At least if it's unstoppable we can use it as a free source of energy! [[Special:Contributions/172.69.195.62|172.69.195.62]] 14:01, 24 March 2025 (UTC)

As a woodworker, one note I would like to make is that while the sawblade ''can'' be damaged by cartridge activation, it is not ''required'' that it be replaced. It is possible to have the blade inspected and potentially repaired and continue to use it. That is addressed in SawStop's FAQ https://www.sawstop.com/sawstop_faq/can-the-blade-be-reused-if-the-safety-system-brake-is-activated/ [[Special:Contributions/172.69.33.189|172.69.33.189]] 15:04, 24 March 2025 (UTC)

The [citation needed] for violating other laws probably means that law enforcement should issue a citation to the manufacturer. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 15:21, 24 March 2025 (UTC)

General observation from a s/w test engineer/woodworker: Original version of the Sawstop used a shotgun shell to fire a stopper into the sawblade which absolutely did destroy the blade. (and made enough noise to pretty much ensure a 'code brown' if you triggered the stop system.) Newer version uses a high tension spring along with a deformable aluminum stopper assembly to absorb the energy and bring the blade to a stop. The advantage of the deformable aluminum assembly is that you can remove it from the blade (with care) and as noted can put the sawblade back to work. However you need a new ($200-ish) stopper assembly before you can re-start the saw. Having a family member who is a retired emergency room doctor who would regularly email me 'stories from work' of woodworker injuries who came through her ER, I can assure you that a tablesaw is pretty much the most dangerous woodworking tool in a typical woodshop. That being said, its quite amusing to me that "SawStop" became XKCD worthy. SawStop is somewhat notorious in the woodworking community because of their highly obnoxious business practices with regards patent and legal attacks on business competitors who came up with alternative approaches to the 'saw brake' or 'saw safety' system. JC from Canada {{unsigned ip|172.69.33.194}}

Funnily enough this could be practical in robot combat [[Special:Contributions/104.23.190.15|104.23.190.15]]15:01, 24 March 2025 EST

Note that since the blade is spun up using explosives and not the electric motor (even ignoring the title text), the saw being unplugged in no way makes the blade safe to touch. [[Special:Contributions/172.68.23.226|172.68.23.226]] 20:03, 24 March 2025 (UTC)

The explosive charge whould already be deadly. --[[User:Bb777|[insert signature here]]] ([[User talk:Bb777|talk]]) 00:31, 25 March 2025 (UTC)

Why is it important to include the fact that this could be used in robot warfare? [[User:Ozymandias|Ozymandias]] ([[User talk:Ozymandias|talk]])

Talk:3067: SawStart

2025-03-25T09:30:47Z

Ozymandias:

It's weird seeing a totally empty explanation, also whats the point of sawstop, don't they just use vibrating blades? [[Special:Contributions/104.23.190.110|104.23.190.110]] 12:40, 24 March 2025 (UTC)
:SawStop is for rotating blades, like you would use for sawing wood. I'm sure there's a good reason why they don't use vibrating blades there, the most likely is "wood is harder than a plaster cast". I could also imagine that vibrating blades don't create nice cuts, which doesn't matter with a plaster cast that will be disposed of, but very much matters with wood used for construction. --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 13:16, 24 March 2025 (UTC)

empty explanation is freaky woah [[Special:Contributions/172.69.194.204|172.69.194.204]] 12:42, 24 March 2025 (UTC)
:Every explanation is empty, at least for a short amount of time. And this is not the earliest that a comic went up (shortly after midday, UK time, when it's not unknown for them to not arrive until after the midnight at the end of the designated publication day), but it looks like you (both, including first-poster at the top) have had the good luck/fortune to be just casually checking for new changes to old articles on the site and instead get 'first look' at the newest addition to it. Of course, it'll be a few hours before most of the article gets fine-tuned into some form of 'completion'. [[Special:Contributions/172.70.86.157|172.70.86.157]] 13:23, 24 March 2025 (UTC)
sudo systemctl stop saw-start.service [[Special:Contributions/172.69.208.132|172.69.208.132]] 13:11, 24 March 2025 (UTC)
:yay you saved the world! --[[User:Bb777|hi]] ([[User talk:Bb777|talk]]) 14:08, 24 March 2025 (UTC)
:"Failed to stop saw-start.service: Access restricted by systemd security policies"

:sudo holding-in-the-power-button doesn't work either.[[Special:Contributions/172.69.34.139|172.69.34.139]] 17:26, 24 March 2025 (UTC)

I'm 99% sure that the system is designed to start a ''stopped'' blade up to full speed within milliseconds, not just increase the speed of a spinning blade. --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 13:22, 24 March 2025 (UTC)

WAITER, WAITER, MORE [[Black Hat]] PLEASE [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 13:31, 24 March 2025 (UTC)

Because of gyroscopic precession, a still spinning (unstoppable?) blade, removed from its axle and housing, would be /very/ difficult and dangerous to dispose of. I'm a woodworker and I think I'll be having nightmares tonight.
-DW [[Special:Contributions/172.69.23.176|172.69.23.176]] 13:36, 24 March 2025 (UTC)

: At least if it's unstoppable we can use it as a free source of energy! [[Special:Contributions/172.69.195.62|172.69.195.62]] 14:01, 24 March 2025 (UTC)

As a woodworker, one note I would like to make is that while the sawblade ''can'' be damaged by cartridge activation, it is not ''required'' that it be replaced. It is possible to have the blade inspected and potentially repaired and continue to use it. That is addressed in SawStop's FAQ https://www.sawstop.com/sawstop_faq/can-the-blade-be-reused-if-the-safety-system-brake-is-activated/ [[Special:Contributions/172.69.33.189|172.69.33.189]] 15:04, 24 March 2025 (UTC)

The [citation needed] for violating other laws probably means that law enforcement should issue a citation to the manufacturer. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 15:21, 24 March 2025 (UTC)

General observation from a s/w test engineer/woodworker: Original version of the Sawstop used a shotgun shell to fire a stopper into the sawblade which absolutely did destroy the blade. (and made enough noise to pretty much ensure a 'code brown' if you triggered the stop system.) Newer version uses a high tension spring along with a deformable aluminum stopper assembly to absorb the energy and bring the blade to a stop. The advantage of the deformable aluminum assembly is that you can remove it from the blade (with care) and as noted can put the sawblade back to work. However you need a new ($200-ish) stopper assembly before you can re-start the saw. Having a family member who is a retired emergency room doctor who would regularly email me 'stories from work' of woodworker injuries who came through her ER, I can assure you that a tablesaw is pretty much the most dangerous woodworking tool in a typical woodshop. That being said, its quite amusing to me that "SawStop" became XKCD worthy. SawStop is somewhat notorious in the woodworking community because of their highly obnoxious business practices with regards patent and legal attacks on business competitors who came up with alternative approaches to the 'saw brake' or 'saw safety' system. JC from Canada {{unsigned ip|172.69.33.194}}

Funnily enough this could be practical in robot combat [[Special:Contributions/104.23.190.15|104.23.190.15]]15:01, 24 March 2025 EST

Note that since the blade is spun up using explosives and not the electric motor (even ignoring the title text), the saw being unplugged in no way makes the blade safe to touch. [[Special:Contributions/172.68.23.226|172.68.23.226]] 20:03, 24 March 2025 (UTC)

The explosive charge whould already be deadly. --[[User:Bb777|[insert signature here]]] ([[User talk:Bb777|talk]]) 00:31, 25 March 2025 (UTC)

Why is important to include the fact that this could be used in robot warfare? [[User:Ozymandias|Ozymandias]] ([[User talk:Ozymandias|talk]])

3067: SawStart

2025-03-25T09:24:48Z

Ozymandias: I changed the language in paragraph 2 to be clearer and grammatically correct.

{{comic
| number = 3067
| date = March 24, 2025
| title = SawStart
| image = sawstart.png
| imagesize = 290x313px
| noexpand = true
| titletext = Unfortunately, SawStart is one-use-only. Once started, the blade cannot be stopped, and must be replaced with a fresh blade while the running one is carefully disposed of.
}}

==Explanation==
{{incomplete|Created by a SawBOT - - Language is too informal and convoluted.}}
{{w|SawStop}} is an American {{w|table saw}} manufacturer whose product is designed to increase safety. Table saws can be highly dangerous if not used properly, because they feature a rapidly spinning {{w|circular saw}} protruding from the surface. If any part of someone's body comes into contact with the blade while it's spinning, it can cause severe injury or death. SawStop products feature an automatic brake, designed to detect when flesh comes into contact with the blade. According to manufacturer claims, the brake (an aluminum block) will stop the blade within 5 milliseconds of detecting contact, followed by the blade retracting into the table. This is intended to prevent major injuries in the event of contact.

Black Hat here takes the notion of a product designed to increase safety, and changes the design to do the opposite, making it much more dangerous. Like the SawStop design, his product ostensibly detects contact with skin and reacts within milliseconds, but rather than stopping the blade, his product uses an explosive charge to ''start'' a stationary blade. It's unknown whether the blade would be faster than normal, and actually make it more dangerous (ordinary speeds of a table saw are more than capable of destroying living tissue), but setting off an explosive charge while in contact with such a blade is probably not a particularly good idea.{{Citation needed}} It is not wise, in general, to touch even a normal stopped blade (without being absolutely certain that the power cannot be turned on and the blade is not sharp enough to be dangerous at rest), but in this case it specifically is designed to make one that theoretically could be touched run up to significantly damaging speeds the moment it is. There is no benefit to such a system, and it exists solely to be malicious (which is likely why it's "less popular").

The title text refers to the fact that the braking feature on the SawStop is single use. Because of the very fast response time, both the braking cartridge and the saw blade will be badly damaged in the process, and both will need to be replaced (this being considered preferable to the kinds of permanent injuries that can result from a spinning blade). The SawStart is also single use, but in its case, it somehow makes the blade impossible to stop, violating the second law of thermodynamics and probably several other laws.{{Citation needed}} Hence, the SawStart blade must also be replaced, but this apparently has to be done while the blade is spinning. To attempt to remove a spinning blade is incredibly dangerous, and this simply adds to the unnecessary harm this product could do.

In theory, such system could be useful on futuristic mechanized melee weapon (like "chainswords" from ''Warhammer 40000''). In which case, saw would start spinning as soon as it hits the enemy - therefore not needing time to spin up; on top of that, the saw is impossible to stop, and will continue to rip and shred any enemies in contact until saw breaks. Naturally, it is possible to make combat disk saw, designed to cut armor and flesh alike.

A similar thing was done in [[2876: Range Safety]], but that time was with a rocket.

==Transcript==
:[A table with a table saw stands behind Black Hat who gestures to the table while facing Megan and Cueball. There is a label on the side of the table, a logo of a circular saw blade, with the first part of a word inside the blade:]
:SawStart
:Black Hat: When the saw detects contact with skin, an explosive charge starts the blade spinning at full speed within a few milliseconds.

:[Caption below the panel:]
:SawStop's less-popular competitor

{{comic discussion}}

[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Cueball]]