explain xkcd - User contributions [en]

3158: Shielding Chart

2026-05-18T01:46:55Z

2603:6011:1F0:2A40:40CE:4E81:F3D4:9FA9: /* Explanation */

{{comic
| number = 3158
| date = October 22, 2025
| title = Shielding Chart
| image = shielding_chart_2x.png
| imagesize = 740x720px
| noexpand = true
| titletext = Sharks can occasionally travel short distances through air when pursuing prey, but their attenuation coefficient is pretty high.
}}

==Explanation==
This comic is part of a series on [[:Category:Confusion matrices|confusion matrices]].

Various hazardous (or merely obnoxious) materials, objects, and effects can have their danger reduced with specialized protective equipment. The yellow squares are where the shield fails to protect against the object. The grey-yellow squares are where the shield is partially successful, but still presents some risk. The grey squares are where the shield succeeds.

The first five barriers are materials/conditions which may be used to block some things and not others, which makes for a relatively normal comparison matrix. The last five barriers are devices which are deliberately designed and manufactured to block the last five materials/effects. Comparing those with effects for which they aren't designed is presented for absurdity.

The first three hazards - Gamma Rays, Neutrons, and Alpha Particles - represent different types of radiation. Their associated "beep" and "click" sounds mirror real detection behavior: "beep" corresponds to ionizing radiation like gamma and alpha particles, detected by modern radiation detectors, while "click" refers to neutron detection, which uses a separate type of counter designed for neutral particles. {{w|Geiger counter|Geiger counters}}, an earlier form of radiation detector, also clicked.

All but two tiles feature [[Cueball]] (or in two cases [[Hairy]]) trying to make use of that column's chosen 'protective shield', although in the case of some scenarios (involving vacuum or water) he may also be sufficiently equipped against the environment he finds himself in. Also present will be the row's specific 'effect', either in its own right (an object or creature that embodies the phenomenon automatically) or as conveyed by [[Megan]] (when not just present as onlooker) who may also have had the 'shield' primarily delegated to her. The two main exceptions are where Cueball himself emits the sound (from within 'protective' suits that turn out to be ineffectual sound-blockers), to apparently annoy Megan, and depictions of radio reception (which always show Cueball's attempt to transmit, whether or not it shows a successful incoming message).

Some hazards, such as {{w|alpha particles}}, a form of radiation with particularly low penetrative power, can be easily deterred by common things; even a relatively short distance through air is enough to minimize their impact. Comparatively, more dangerous hazards, such as the far more penetrative {{w|gamma rays}}, are unaffected by all but the shielding methods actually intended for them. No effect is either all effective or all ineffective, against each form of 'shielding', and neither is any instance of shield consistent against all effects.

The title text notes that, while the shark hazard is shown on the chart to be entirely nullified by a sufficient air barrier, in reality sharks are capable of attacking prey even if it is a short distance out of the water. However, it claims a high "attenuation coefficient", which is an {{tvtropes|ExpospeakGag|overly scientific way of saying}} that you don't need a ''lot'' of air between you and the shark before it can't hurt you. Indeed, while sharks can jump out of the water to a certain height, there's a hard line between "vulnerable" and "out of reach", and a person can be within arm's reach of a shark's attack while they themselves are in no danger whatsoever. So long as they ''don't'' unwisely reach out to tempt fate.

This table might imply that lead is the best defense against everything in general, but it is toxic, so don't bring lead with you at all times.

Cueball saying "Kitty!" in the shark hazard row most likely is a reference to [[231: Cat Proximity]].

===Table===
{| class="wikitable" | style="background:#E6C3C3;"
! Shielding Chart
! scope="col"| {{w|Air}}
! scope="col"| {{w|Lead}}
! scope="col"| {{w|Water}}
! scope="col"| {{w|Glass}}
! scope="col"| {{w|Vacuum}}
! scope="col"| {{w|Oven mitts}}
! scope="col"| {{w|Armor}}
! scope="col"| {{w|Hazmat suit|Bio-hazard suit}}
! scope="col"| {{w|Faraday cage}}
! scope="col"| {{w|Shark cage}}
|-
! scope="row"| {{w|Gamma rays}}
| style="background:#FFF978;"|Gamma rays are not significantly shielded by air.
| style="background:#C4C5C7;"|Lead is commonly used as {{w|Lead shielding|shielding}} against gamma rays. Lead works because of its density and high atomic number, scattering gamma rays.
| style="background:#DDDCB2;"|Water can be used to shield against gamma rays, but you need at least 10 feet of water between you and the gamma rays for it to work.
|colspan=7; style="background:#FFF978;"|Gamma rays have the highest energy of any type of light and have no mass or charge, making them pass through most materials easily.

|-
! scope="row"| {{w|Neutrons}}
| style="background:#FFF978;"|Neutrons are not stopped by low-density materials such as air.
| style="background:#DDDCB2;"|Lead's high density means that neutrons will keep bumping into lead nuclei, losing their energy through inelastic scattering. However since lead nuclei are much heavier than neutrons, most of the energy will remain with the neutron; as a result, many collisions are needed to slow the neutrons. Some neutrons will also be absorbed by the nuclei, although the {{w|Cross section (physics)|cross section}} is rather low.
| style="background:#C4C5C7;"|Since protons and neutrons have almost the same mass, a collision with a hydrogen atom in water will result in the neutron losing almost half of its energy, resulting in a very rapid attenuation. Moreover the cross section for the fusion of neutrons and protons is high, leading to most neutrons being captured to form deuterium.
|colspan=7; style="background:#FFF978;"|None of these materials are dense enough to slow or absorb neutrons in significant quantities.

|-
! scope="row"| {{w|Alpha particles}}
|colspan=4; style="background:#C4C5C7"|As alpha particles are almost completely unable to travel through most materials, any of these would effectively stop them. Even if they didn't, the intervening air and distance to Cueball would prevent them being detected in any case. In the third panel, Cueball questions if his equipment is working, as this is the only thing which isn't detected within the first four shields.
| style="background:#FFF978;"|While alpha particles are unable to travel through air, they can move freely in a vacuum. As such, alpha particles are able to reach Cueball in this scenario, activating his detector and allowing Cueball to know that his equipment is indeed working properly.
|colspan=3; style="background:#C4C5C7;"|As with the first four shields, any of these materials would block the particles, and in any case they would have a hard time travelling through air to reach Cueball regardless of the shield provided.
|colspan=2; style="background:#FFF978;"|There are gaps in both the cages through which the particles could pass. In both cases, the emitter has been moved closer to the observer, because otherwise the effect would be masked by the intervening air.

|-
! scope="row"| {{w|Light}}
| style="background:#FFF978;"|Light passes easily through air; if it didn't, we would not be able to see.
| style="background:#C4C5C7;"|As lead is a solid, opaque material, light is not able to pass through it.
| style="background:#DDDCB2;"|Water is mostly transparent to visible light. It will attenuate over long distances, but won't be quickly blocked.
| style="background:#FFF978;"|As glass is a largely transparent substance, light is usually able to pass through it.
| style="background:#FFF978;"|Because a lack of air does not impact the travel of light, it reaches Cueball without issue.
| style="background:#C4C5C7;"|Cueball is able to use the opaque oven mitts to cover the light source, successfully preventing the light from reaching him.
| style="background:#C4C5C7;"|The helmet Cueball is wearing, except the eye slit, is opaque, blocking the light from reaching him.
| style="background:#C4C5C7;"|As with the oven mitts, Hairy uses the helmet part of the biohazard suit to block the light source.
|colspan=2; style="background:#FFF978;"|As both types of cages have holes in them, it is easy for the light to pass through the holes and reach Cueball.

|-
! scope="row"| {{w|Sound}}
| style="background:#FFF978;"|Air is the most common medium through which we perceive sound. It would not serve as an effective barrier between a source of sound and someone's ears, unless it was over a very great distance.
| style="background:#FFF978;"|Lead is very dense, and is in fact used for soundproofing due to its resistance to buffeting by airborne sound waves. But, as an extremely dense solid, it is a very fast conductor of vibration within itself (so long as the thickness of the material does not invoke the dampening softness and attenuate those vibrations). In this case, Megan is directly knocking upon the lead screen itself, which seems to be enough for the sound of the knocking to emerge at Cueball's side.
| style="background:#FFF978;"|Sound travels significantly faster and further in water than in air, making it difficult to locate and understand, but certainly not doing any good when it comes to ''blocking'' sound. The image in this square is of a dolphin,<sup>[[[285: Wikipedian Protester#top|''cetacean needed'']]]</sup> detecting fish using sound waves, which it is very good at doing precisely ''because'' its sounds travel very well through water.
| style="background:#FFF978;"|Glass, while useful for muffling sound, cannot block it entirely, as anyone whose neighbors mow the lawn at 6:00 can attest to.
| style="background:#C4C5C7;"|"In space, no one can hear you scream." In a vacuum (like space), there are no atoms or molecules to carry sound waves.
| style="background:#DDDCB2;"|Oven mitts are thick enough that they block some of the sound if a person shouts into them, but it will not be enough to fully block out the sound.
| colspan=2; style="background:#FFF978;"|The two cases of whether sound can penetrate suits are the only two cases where Cueball is trying (successfully) to inflict the phenomenon on [[Megan]], who otherwise features only as the (attempted) instigator. Neither suit is able (or intended) to significantly block sound waves.
| colspan=2; style="background:#FFF978;"|The cages are open enough that their ability to block sound is negligible, and standing in one will do very little to block out sound.

|-
! scope="row"| {{w|Heat}}
| style="background:#FFF978;"|Air can be a fairly effective thermal insulator when constrained, as in {{w|aerogels}} and many types of insulation. However, freely moving air as depicted in this panel flows as it heats up, transferring heat from the campfire to Cueball's marshmallow. Additionally, air does little to block thermal radiation from the heat source.
| style="background:#FFF978;"|Lead conducts heat, allowing Cueball to toast a marshmallow on the surface of the shield. However, since lead is poisonous, he should not do this.
| style="background:#FFF978;"|Heat will raise the temperature of water. If the temperature is raised high enough the water will start to boil; boiling has long been used by humanity to prepare food. Marshmallows however are not meant to be boiled.{{Citation Needed}}
| style="background:#FFF978;"|Cueball appears to be holding a glass bottle over an open fire, into which he has presumably placed his marshmallows. Depending on the temperature, the type of glass, and its thickness, it is possible to heat the contents of a glass container this way, but if the container is unsuitable this can be dangerous to the user, because the glass may abruptly shatter. Also, it is unclear how he proposes to consume the sticky marshmallow mess this would create.
| style="background:#DDDCB2;"|The lack of matter in a vacuum completely blocks transmission by conduction and convection, the two main ways in which heat is spread. It still allows transmission by radiation, which is less efficient. For the specific example of the thermos shown in the image, the way they are constructed completely blocks radiation, but there are enough residual air particles for a very slow convection. The fact that the shielding is made from one single (very thin) piece, and it has lips, also allows some conduction.
| style="background:#C4C5C7;"|Cueball is holding a pan over an open fire while wearing oven mitts. Pans whose grip or handle is not made of a material that conducts less heat than the pan proper are dangerous to grab onto with one's bare hands: wearing oven mitts protects the user from heat. It should be noted that, depending on the weight of the pan and the time the pan needs to be held over a fire to prepare its contents, this can be quite tiring for the user. Also, this implies that oven mitts are a better heat shield than a vacuum, which isn't correct (at least as far as pure heat conduction goes).
| style="background:#FFF978;"|A suit of armor is made of metal, which will conduct the heat and do little to protect one's hands against an open flame. The inside of the gloves will be made of some kind of cloth and/or leather, which, as well as giving little protection, might pose a fire hazard.
| style="background:#FFF978;"|Bio-hazard suits are designed to help filter air and allow the user to handle dangerous chemicals. However, most bio-hazard suits are made out of fabrics with a laminate coating, both of which are prone to burning and allow heat to pass through.
| colspan=2; style="background:#FFF978;"|Both cages have a minimal effect on the heat from a fire. Depending on the intensity of the fire and the distance from the cage this can create a comfortably warm temperature to the person inside of the cage.

|-
! scope="row"| {{w|Swords}}
| style="background:#FFF978;"|Air exerts negligible force against objects of such high density at low speed, and cannot stop Megan's sword's thrust.
| style="background:#C4C5C7;"|Lead is a heavy and dense metal, and as a result, it can stop blows from a sword.
| style="background:#FFF978;"|While water has a greater force than air against objects, it is still not enough to stop Megan's attack.
| style="background:#FFF978;"|Glass is easily broken by sharp blows, especially if it isn't tempered, and as a result does not stop Megan's sword.
| style="background:#FFF978;"|A vacuum has no resistance against objects and unsurprisingly is not able to stop Megan's attack.
| style="background:#FFF978;"|Oven mitts are typically made of fabric, which would provide only limited protection. They also do not cover the full body.
| style="background:#C4C5C7;"|The metallic armor Cueball is wearing was probably designed to stop penetrating and slashing sword blows, with further layers beneath to dampen impacts.
| style="background:#FFF978;"|Swords are sharp, and as such are able to break through the thin hazmat suit Cueball is wearing.
| style="background:#FFF978;"|A Faraday cage can be a fine mesh, optimal to screen out various radio frequencies of EM radiation but not intended to stop anything else and comparatively delicate against any physical penetration.
| style="background:#FFF978;"|A shark cage, while able to provide resistance against larger threats, has holes through which Megan's sword can go.

|-
! scope="row"| {{w|Particulate matter#Health problems|Toxic dust}}
| style="background:#FFF978;"|Dust can travel through air, hanging onto small currents. Air does nothing to protect Cueball.
| style="background:#DDDCB2;"|{{w|Lead poisoning|Lead is poisonous}}, so while a solid lead barrier would prevent toxic dust from passing through, any dust or metal fragments from the shield would still be dangerous.
| style="background:#FFF978;"|Water actually can be {{w|Dust abatement|used to prevent the spread of dust}}. However, toxic dust that gets into drinking water will {{w|Water pollution#Groundwater pollution|contaminate it}}, and could cause health problems, just as airborne toxic dust can.
| style="background:#C4C5C7;"|Dust cannot travel through glass, and being fully encased in a glass bell protects one from dust (though it would bring its own problems).
| style="background:#FFF978;"|With no air to slow it down, dust in space can move at dangerously high speeds, possibly fast enough to tear through Cueball's space suit.
| style="background:#FFF978;"|Oven mitts are worn on the hands and do not normally interfere with one's breathing. However, if there is a notable amount of toxic dust in the air, holding an oven mitt over one's face is better than no protection.
| style="background:#FFF978;"|A suit of armor still allows the wearer to breathe, and provides no particular protection from dust.
| style="background:#C4C5C7;"|A biohazard suit is fully enclosed with its own internal oxygen supply, and so protects the wearer from airborne particles.
| colspan=2; style="background:#FFF978;"|Both cages are too open to provide any significant protection against dust.

|-
! scope="row"| {{w|Radio}}
| style="background:#FFF978;"|Radio waves are more than able to travel through air. This is what allows walkie-talkies to work.
| style="background:#C4C5C7;"|Although lead is a relatively poor conductor and therefore attenuates radio waves less than most metals, a lead enclosure can still work as a Faraday cage with a sufficiently thick layer of lead.
| style="background:#C4C5C7;"|Radio waves from two-way radios, like the kind shown in the comic, {{w|Radio propagation#Direct modes (line-of-sight)|cannot penetrate deep water}}. There are {{w|Radio propagation#Surface modes (groundwave)|radio frequencies that ''can'' penetrate deep water}}, but these have a much lower frequency, require more powerful transmitters, and (in the case of {{w|Extremely low frequency#Difficulties of ELF communication|extremely low frequencies}}) cannot transmit audio.
| style="background:#FFF978;"|In a similar way that glass is transparent to visual light, it is also transparent to radio waves, allowing them to pass through. It is also in this frame that Cueball begins to have doubts about whether being put in a glass case is part of his mission.
| style="background:#FFF978;"|As there is nothing getting in the way of radio waves in a vacuum, radios work very well in space. This allows ground control to communicate with astronauts in space.
| style="background:#FFF978;"|Oven mitts, typically being made of fabric, have no effect on radio waves.
| style="background:#C4C5C7;"|A metal suit of armor blocks radio waves. This is because metals are very good electrical conductors, which block the radio waves.
| style="background:#FFF978;"|Biohazard suits do not block radio waves, and someone wearing such a suit can send and receive radio transmissions without issue.
| style="background:#C4C5C7;"|A {{w|Faraday cage}} is specifically designed to block electromagnetic fields such as radio waves. In fact, this is the ''only'' thing listed that it blocks.
| style="background:#FFF978;"|The openings in a shark cage are too wide for the cage to experience the properties of a Faraday cage. Cueball again questions why his mission requires this particular protective equipment.

|-
! scope="row"| {{w|Sharks}}
| style="background:#C4C5C7;"|Sharks cannot travel very far on land or in the air.
| style="background:#C4C5C7;"|Shielding yourself with lead plates will effectively protect you against sharks.
| style="background:#FFF978;"|Sharks live in water, so water is not an effective shield against sharks.{{cn}}
| style="background:#C4C5C7;"|Glass will effectively protect you against sharks, provided that it is thick enough. In fact, sharks are commonly (and safely) shown to the public in aquariums.
| style="background:#C4C5C7;"|In the vacuum of space, Cueball is very far from sharks' ocean habitat (though he may be at risk of [https://www.youtube.com/watch?v=y5xcvAoKojo dolphins]).
| style="background:#FFF978;"|Although shark-shaped oven mitts are quite common due to their similar appearance, oven mitts are not very effective at stopping sharks.{{cn}}
| style="background:#DDDCB2;"|Depending on the design of the armor, a shark might be able to permanently deform it enough that it causes injury, though the more flexible {{w|Chain_mail#Practical_uses|chain mail}} ''is'' successfully used to prevent actual piercing damage from bites.
| style="background:#FFF978;"|A biohazard suit is weak enough that a shark can rip through it.
| style="background:#FFF978;"|A Faraday cage is weak enough that a shark can rip through it.
| style="background:#C4C5C7;"|A shark cage is specifically designed to protect against sharks. In fact, this is the ''only'' hazard here that it blocks.
|}

==Transcript==
{{incomplete transcript|Check if it's complete.}}
:[The whole comic is in one panel]
:[A 10x10 matrix sits in the middle with rows labelled as follows:]
:Gamma Rays
:Neutrons
:Alpha Particles
:Light
:Sound
:Heat
:Swords
:Toxic Dust
:Radio
:Sharks
:[The columns are:]
:Air
:Lead
:Water
:Glass
:Vacuum
:Oven Mitts
:Armor
:Bio-Hazard Suit
:Faraday Cage
:Shark Cage


:[In all of the Gamma Ray boxes, Cueball stands next to a gamma ray emitter with a smattering of dots a short distance away from it, which is perched on a table as necessary, a geiger counter held in his hand or worn.]

:[Gamma Rays vs. Air - yellow tile]
:[Just standing a few feet from the emitter. The geiger counter Cueball wears beeps three times:] Beep Beep Beep!

:[Gamma Rays vs. Lead - gray tile]
:[The gamma ray emitter and the table have a lead enclosure covering them. The geiger counter, held towards everything else in Cueball's hand, does not beep.]

:[Gamma Rays vs. Water - grayish-yellow tile]
:[The gamma ray emitter and table are placed in a large, nearly full, glass of water. Cueball's outstretched geiger counter beeps once:] Beep!

:[Gamma Rays vs. Glass - yellow tile]
:[A glass 'bell-jar' covers the gamma ray emitter, atop the table, the geiger counter beeps three times:] Beep Beep Beep!

:[Gamma Rays vs. Vacuum - yellow tile]
:[The gamma ray emitter appears to be held within an open hatch of a satellite. The satellite, together with a spacesuited Cueball, can be seen to be in orbit around the Earth. His chest-mounted geiger counter is transmitting three beeps:] Beep Beep Beep

:[Gamma Rays vs. Oven Mitts - yellow tile]
:[Megan stands to the left of the gamma ray emitter, wearing oven mitts and covering the emitter with one hand. Cueball’s body-mounted geiger counter beeps three times:] Beep Beep Beep

:[Gamma Rays vs. Armor - yellow tile]
:[Cueball stands to the right of the gamma ray emitter wearing a suit of plate armor. From inside the armor, his Geiger counter beeps three times:] Beep Beep Beep

:[Gamma Rays vs. Bio-Hazard Suit - yellow tile]
:[Cueball stands to the right of the gamma ray emitter wearing a bio-hazard suit. From inside the suit, his Geiger counter beeps three times:] Beep Beep Beep

:[Gamma Rays vs. Faraday Cage - yellow tile]
:[Cueball is surrounded by a mesh cage. His geiger counter beeps three times:] Beep Beep Beep

:[Gamma Rays vs. Shark Cage - yellow tile]
:[Cueball is within a barred cage. His geiger counter beeps three times:] Beep Beep Beep

:[In all of the Neutron boxes, Cueball stands next to a neutron emitter, that looks like two half-sphere shells that are angled slightly open in Cueball's direction, in similar scenarios to the above but with a heftier pedestal in place of the table. No visible effects emit from the emitter. Cueball holds the top handle of the same large detector in each scenario.]

:[Neutrons vs. Air - yellow tile]
:[The detector emits two clicks:] Click Click

:[Neutrons vs. Lead - grayish-yellow tile]
:[The emitter and pedestal are within their lead enclosure. The detector clicks once:] Click

:[Neutrons vs. Water - gray tile]
:[The emitter and pedestal are in the large glass of water. The detector makes no noise.]

:[Neutrons vs. Glass - yellow tile]
:[The glass bell-jar covers the pedestalled emitter. The detector clicks twice:] Click Click

:[Neutrons vs. Vacuum - yellow tile]
:[The emitter sits in the satellite's open hatch. Spacesuited Cueball's hand-held detector transmits two clicks:] Click Click

:[Neutrons vs. Oven Mitts - yellow tile]
:[Megan wears oven gloves and covers the emitter, on its pedestal, with both hands. Cueball's detector clicks twice:] Click Click

:[Neutrons vs. Armor - yellow tile]
:[Cueball has removed his armor’s helmet and placed it over the emitter. His detector clicks twice:] Click Click

:[Neutrons vs. Bio-Hazard Suit - yellow tile]
:[Cueball stands as normal, having draped his unworn biohazard suit over the emitter, leaving the hood on the floor. His detector sounds two clicks:] Click Click

:[Neutrons vs. Faraday Cage - yellow tile]
:[Within his mesh cage, two clicks come from Cueball's detector:] Click Click

:[Neutrons vs. Shark Cage - yellow tile]
:[Within a barred cage, the detector Cueball holds clicks twice:] Click Click

:[In all of the Alpha Particle boxes, it is a small spherical mass or flask with 'fizzy' strands or dashes, set in the same base scenarios as previously.]

:[Alpha Particles vs. Air - gray tile]
:[Cueball is holding a detector and looking at it. The detector is doing nothing.]

:[Alpha Particles vs. Lead - gray tile]
:[There is a lead wall between the alpha particle source and Cueball. Cueball's worn detector is doing nothing.]

:[Alpha Particles vs. Water - gray tile]
:[The alpha particle item is stood in a large glass of water. Cueball is holding a detector and looking at it. The detector is doing nothing.]
:[Cueball:] Does this thing even work?

:[Alpha Particles vs. Glass - gray tile]
:[The source, on its table, is covered by a bell-jar. Cueball stands looking at it, wearing a detector that does nothing.]

:[Alpha Particles vs. Vacuum - yellow tile]
:[The source of alpha particles is inside the open satellite hatch. Spacesuited Cueball floats nearby, with a detector that transmits three beeps:] Beep Beep Beep

:[Alpha Particles vs. Oven Mitts - gray tile]
:[Megan wears over mitts, placing one over the source on its table. Cueball looks ok, his worn detector doing nothing.]

:[Alpha Particles vs. Armor - gray tile]
:[Cueball, in his full suit of armor, has picked up the source from its table and is holding it directly in his hand. There is no sign of any detector activity occuring.]

:[Alpha Particles vs. Bio-Hazard Suit - gray tile]
:[Cueball, wearing the bio-hazard suit, looks impassively at the source on the top of its table. There are no beeps.]

:[Alpha Particles vs. Faraday Cage - yellow tile]
:[The table with the source has been moved to be right next to the mesh cage. Cueball, inside the cage, presses right up to the inside of the same mesh edge, putting his detector right next to it. There are three beeps:] Beep Beep Beep

:[Alpha Particles vs. Shark Cage - yellow tile]
:[Again, the source, on its table, is right next to the bars of the cage. And, again, Cueball is pressed right up against (and perhaps through) the inside edge of the cage. Three beeps sound:] Beep Beep Beep

:[In all of the light boxes, Megan points a brightly lit battery torch towards Cueball.]

:[Light vs. Air - yellow tile]
:[Megan points the torch towards Cueball. Rays of lights splay out over Cueball's face as he instinctively holds one arm protectively over his eyes.]
:[Cueball:] Ow.

:[Light vs. Lead - gray tile]
:[Megan points the torch towards Cueball, but only illuminates a lead wall that stands between them. Cueball makes no reaction.]

:[Light vs. Water - grayish-yellow tile]
:[Megan stands nose-deep in the giant glass of water, aiming her shining torch out through the water and out of the glass towards Cueball. Cueball shields his eyes with his arm, but is silent.]

:[Light vs. Glass - yellow tile]
:[Megan stands within a person-sized bell-jar, shining her torch towards Cueball, who is outside and shielding his eyes.]
:[Cueball:] Ow.

:[Light vs. Vacuum - yellow tile]
:[Megan and Cueball, in spacesuits (i.e. with 'fishbowl helmets'), are seen orbiting high above the planet below. Megan holds a torch, shining it towards Cueball.]
:[Cueball:] Ow.

:[Light vs. Oven Mitts - gray tile]
:[Megan points her torch towards Cueball. Cueball wears oven-gloves, and casually holds one begloved hand over the end of the torch, from which no light is seen.]

:[Light vs. Armor - grey tile]
:[Megan shones her torch upon the armored figure of Cueball, whose helmet visor is down.]
:[Cueball:] Nope.

:[Light vs. Bio-Hazard Suit - grey tile]
:[Megan makes to point her torch at Cueball, who is dressed in all but the hood of his bio-hazard suit. He holds the hood out, fully covering Megan's torch.]

:[Light vs. Faraday Cage - yellow tile]
:[The torch is pointed by Megan towards Cueball, arm across his eyes as he stands within in his mesh cage.]
:[Cueball:] Ow.

:[Light vs. Shark Cage - yellow tile]
:[Megan's torch shines through the bars of the cage at Cueball, his arm protectively held up.]
:[Cueball:] Ow.

:[In most of the sound boxes, Megan appears to be screaming in Cueball's direction.]

:[Sound vs. Air - yellow tile]
:[Cueball stands with his hands over his ears, as a tensed-up Megan lets out a loud scream.]
:[Megan:] AAAAAAAAA!

:[Sound vs. Lead - yellow tile]
:[Between Megan and Cueball is a full-height thick lead wall. Megan is tapping on her side.]
:[Megan:] Knock Knock
:[Cueball:] Who is it?

:[Sound vs. Water - yellow tile]
:[An underwater scene, showing sea-floor with various corals/sea-plants. Just above is a dolphin, projecting sound waves towards two small fish.]

:[Sound vs. Glass - yellow tile]
:[Megan is stood within her person-sized bell-jar, screaming loudly. The bell-jar is vibrating. Cueball is covering his ears.]
:[Megan, in notably distorted text:] AAAAAAAA!

:[Sound vs. Vacuum - grey tile]
:[Megan and Cueball float in space, high above the planet. They are both wearing space helmets. An abortive speech-bubble emerges from Megan's helmet.]
:[Megan:] .....

:[Sound vs. Oven Mitts - greyish-yellow tile]
:[Megan stands to the left of Cueball, wearing oven-gloves. Her hands are over her mouth, muffling her attempts to say anything.]
:[Megan:] <two lines of unintelligble sounds>

:[Sound vs. Armor - yellow tile]
:[Megan is holding her hands over her ears. Cueball is wearing his suit of armor, which is vibrating, while he emits a large scream.]
:[Cueball:] AAAAAAAAA!

:[Sound vs. Bio-Hazard Suit - yellow tile]
:[Megan has her hands over her ears. Cueball is screaming from within his bio-hazard suit.]
:[Cueball:] AAAAAAAAA!

:[Sound vs. Faraday Cage - yellow tile]
:[Megan is yelling at Cueball, standing within his mesh cage with his hands over his ears.]
:[Megan:] AAAAAAAA!

:[Sound vs. Shark Cage - yellow tile]
:[Megan yells, as Cueball holds his hands over his ears behind the bars of the cage.]
:[Megan:] AAAAAAAA!

:[All of the fire boxes show a small campfire, or other more expansive flames. In all but one case, Cueball is present. In most of these instances, he is holding a marshmallow, sometimes at the end of a long stick.]

:[Heat vs. Air - yellow tile]
:[There is a campfire, with Cueball extending a stick-speared marshmallow over it.]

:[Heat vs. Lead - yellow tile]
:[A campfire has a lead slab propped up above it. Cueball's marshmallow-stick is being held to its upper surface.]
:[Marshmallow:] TSSSSS
:[Voice from off-panel:] NO!

:[Heat vs. Water - yellow tile]
:[A campfire heats a cauldron/cooking-pot held over it. Cueball dips his stick with a marshmallow into the container as splashes/vapor emerge. Megan stands behind Cueball.]
:[Cueball:] They're better boiled.
:[Megan:] NO!

:[Heat vs. Glass - yellow tile]
:[With a campfire between them, Megan and Cueball stand with sticks in their hands, held close to the fire. Megan has speared her own marshmallow. Cueball holds something, that looks like a wine bottle, in a forked/looped end, a few small puffs of vapor emerging from open top of the bottle.]

:[Heat vs. Vacuum - greyish-yellow tile]
:[Surrounded by a general setting of flames, there appears to be a cross-section of a vacuum flask. The neck of the flask is plugged. The inside of the flask appears to be half full of liquid with some solid chunks floating in it.]
:[Arrowed label, pointing at the flask's chunks:] Ice

:[Heat vs. Oven Mitts - grey tile]
:[Megan and Cueball stand around the campfire, Megan holding her marshmallow-on-a-stick. Cueball is wearing oven gloves and, with one hand almost over the flames, is holding the handle of a frying pan that is actually in the flames. Something (possibly a marshmallow) seems to be sizzling in the pan.]

:[Heat vs. Armor - yellow tile]
:[Megan is holding her marshmallow stick over the campfire. Cueball is holding his marshmallow over the fire, directly in his gauntleted hand, as he wears the full armor.]
:[Cueball:] OW! OW!

:[Heat vs. Bio-Hazard Suit - yellow tile]
:[Around the campfire, Megan toasts her marshmallow normally. Cueball wears his biohazard suit, holding his gloved hand close to the flames whilst holding a marshmallow.]
:[Cueball:] Ow! Ow!

:[Heat vs. Faraday Cage - yellow tile]
:[The campfire is built just to the left of the mesh cage, within which Cueball is standing.]
:[Cueball:] Mmm, warm.

:[Heat vs. Shark Cage - yellow tile]
:[Cueball's cage has a campfire just outside its bars.]
:[Cueball:] Mmm, warm.



:[In all of the sword boxes, Megan is thrusting a sword rightwards, towards/into Cueball, in this row. Cueball also holds a sword, in all but one case, but lowered and not in a defensive manner.]

:[Swords vs. Air - yellow tile]
:[Megan is poking Cueball with a sword.]
:[Cueball:] Ow.

:[Swords vs. Lead - gray tile]
:[Cueball is standing in a lead container as Megan hits her sword against the outside of it, making a metallic sound:] Clank

:[Swords vs. Water - yellow tile]
:[Cueball and Megan are both underwater, wearing diving gear. Megan is poking Cueball with her sword.]
:[Cueball:] Ow.

:[Swords vs. Glass - yellow tile]
:[Megan is standing in her person-sized bell jar; however, she has smashed a hole in the side and is now poking Cueball with her sword through the hole.]
:[Cueball:] Ow.

:[Swords vs. Vacuum - yellow tile]
:[Cueball and Megan are floating in space, wearing spacesuits. Megan is poking Cueball with her sword.]
:[Cueball:] Ow.

:[Swords vs. Oven Mitts - yellow tile]
:[Cueball stands next to Megan, wearing oven mitts. Megan is poking him with her sword.]
:[Cueball:] Ow.

:[Swords vs. Armor - gray tile]
:[Cueball is standing in a suit of armor next to Megan. She tries to poke him but cannot penetrate the armor, instead producing a metallic "clink"]
:[Cueball:] Ha!

:[Swords vs. Bio-Hazard Suit - yellow tile]
:[Cueball is wearing his biohazard suit as Megan pokes him with her sword.]
:[Cueball:] Ow.

:[Swords vs. Faraday Cage - yellow tile]
:[Cueball is standing inside a person-sized Faraday cage as Megan pokes him with her sword through the mesh.]
:[Cueball:] Ow.

:[Swords vs. Shark Cage - yellow tile]
:[Cueball is standing inside of a shark cage as Megan pokes him with her sword through the bars.]
:[Cueball:] Ow.

:[In all of the tiles in the Toxic Dust row, clouds, and further particulate specks, illustrate the toxic dust, in several cases, apparently being discharged by a burning brazier. All tiles have Cueball in the scene.]

:[Toxic Dust vs. Air - yellow tile]
:[Cueball is standing next to a container resembling a metal trash can, with flames visible on top and a cloud of smoke and particulates rising from the flames.]

:[Toxic Dust vs. Lead - grayish-yellow tile]
:[The burning trash can is encased in a rectangular lead box. Cueball is touching the outside of the lead box as a few particulates are coming off of it.]
:[Cueball:] This shield is also ''producing'' toxic dust.

:[Toxic Dust vs. Water - yellow tile]
:[Cueball and Megan are both standing (presumably) outside, watching as particulates hover in the air. There are a few clouds present as well.]
:[Cueball:] Don't worry, this will all be safely absorbed by the groundwater.

:[Toxic Dust vs. Glass - gray tile]
:[Cueball is standing in a person-sized bell jar as toxic dust floats around the outside of it.]

:[Toxic Dust vs. Vacuum - yellow tile]
:[Cueball is floating in space next to a satellite with an open hatch that is emitting toxic dust.]
:[Satellite:] Achoo!
:[Cueball:] My suit!

:[Toxic Dust vs. Oven Mitts - yellow tile]
:[Cueball is standing next to the burning trash can and covering his face with an oven-mitted hand.]
:[Cueball:] ''Cough''

:[Toxic Dust vs. Armor - yellow tile]
:[Cueball is standing next to the burning trash can in a suit of armor.]
:[Cueball:] ''Cough''

:[Toxic Dust vs. Bio-Hazard Suit - gray tile]
:[Cueball is standing next to the burning trash can while wearing his biohazard suit. He is unaffected by the toxic dust it is producing.]

:[Toxic Dust vs. Faraday Cage - yellow tile]
:[Cueball is standing next to the burning trash can in a person-sized Faraday cage.]
:[Cueball:] ''Cough''

:[Toxic Dust vs. Shark Cage - yellow tile]
:[Cueball is standing in a shark cage next to the burning trash can.]
:[Cueball:] ''Cough''

:[Most tiles in the radio row depict Cueball carrying a two-way radio handset, except where the transceiver appears to be part of the various protective suits that he is wearing.]

:[Radio vs. Air - yellow tile]
:[Cueball is holding a handheld two-way radio in his right hand, close to his face, and speaking into it. A voice from the radio is responding to him.]
:[Cueball:] Eagle Base, come in.
:[Radio:] Go ahead.

:[Radio vs. Lead - gray tile
:[Cueball is standing inside a lead box, again holding the radio close to his face.]
:[Cueball:] Eagle Base, come in? Hello?

:[Radio vs. Water - gray tile]
:[Cueball is underwater, in a diving suit. He is once again holding a hand radio. Bubbles are rising from his helmet and a shark is swimming underneath him.]
:[Cueball:] Hello?

:[Radio vs. Glass - yellow tile]
:[Cueball is standing inside a person-sized bell jar, holding the radio close to his face.]
:[Cueball:] Is this... part of the mission?
:[Radio:] Sure.

:[Radio vs. Vacuum - yellow tile]
:[Cueball is floating in space next to the satellite. He is not visibly holding a radio, implying that it is integrated into his spacesuit.]
:[Cueball:] Eagle Base, I have the package.

:[Radio vs. Oven Mitts - yellow tile
:[Cueball is wearing oven mitts while holding the radio close to his face.]
:[Cueball:] Eagle Base, tactical mitts acquired.
:[Radio:] Copy that.

:[Radio vs. Armor - gray tile]
:[Cueball is standing in a suit of armor. He is not visibly holding a radio.]
:[Cueball:] Repeat that? My suit radio is having issues.

:[Radio vs. Bio-Hazard Suit - yellow tile]
:[Cueball is wearing his biohazard suit. He is not visibly holding a radio.]
:[Cueball: Copy that.]

:[Radio vs. Faraday Cage - gray tile
:[Cueball is standing inside a person-sized Faraday cage, holding the radio close to his face.]
:[Cueball:] Eagle Base? Come in?

:[Radio vs. Shark Cage - yellow tile]
:[Cueball is standing in a shark cage, holding the radio close to his face.]
:[Cueball:] Eagle Base, why am I-
:[Radio:] Don't worry about it.

:[All tiles in the Shark row depict a shark, except when only the shark's fin is seen emerging from a body of water. Cueball is somehow present in each case.]

:[Sharks vs. Air - gray tile]
:[Cueball is standing on land next to a body of water. A shark fin is protruding from the surface of the water.]

:[Sharks vs. Lead - gray tile]
:[Cueball, wearing diving gear, is standing on the ocean floor in a person-sized lead container. A few small fish are swimming above and to the left of him and a shark is floating below the fish.]

:[Sharks vs. Water - yellow tile]
:[Cueball is again underwater, wearing diving gear. He is very close to a shark and seems to be pointing at it.]
:[Cueball:] Kitty!

:[Sharks vs. Glass - gray tile]
:[The shark is now in a water tank, behind a wall of glass. Cueball and Megan are standing next to the tank, looking at what is likely an informative plaque in front of it.]

:[Sharks vs. Vacuum - gray tile]
:[Cueball is floating in space. Earth is visible in the background, with a shark fin visibly protruding from a body of water.]

:[Sharks vs. Oven Mitts - yellow tile]
:[Cueball is underwater, wearing diving gear and oven mitts, he gently touches the shark's snout.]
:[Cueball:] ''Boop!''

:[Sharks vs. Armor - grayish-yellow tile]
:[Cueball is underwater, now wearing a suit of armor. The shark appears to be biting his armored right hand.]
:[Shark:] cronch cronch
:[Cueball:] Ow.

:[Sharks vs. Bio-Hazard Suit - yellow tile]
:[Cueball, underwater and wearing his biohazard suit, is now petting the shark on its snout.]
:[Cueball:] Good kitty!

:[Sharks vs. Faraday Cage - yellow tile]
:[Cueball is inside an underwater Faraday cage, which is suspended by a tether going straight up. The shark is in the process of tearing apart the cage.]
:[Cueball:] ''No! Bad kitty!''

:[Sharks vs. Shark Cage - gray tile]
:[Cueball is underwater, in a shark cage suspended from one side by a tether going straight up. The shark is swimming a short distance away from the cage.]

{{comic discussion}}<noinclude>
[[Category:Confusion matrices]]
[[Category:Sharks]]
[[Category:Multiple Cueballs]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Cueball]]
[[Category:Comics with color]]
[[Category:Comics featuring Hairy]]

3108: Laser Danger

2026-05-18T01:16:22Z

2603:6011:1F0:2A40:40CE:4E81:F3D4:9FA9: /* Explanation */

{{comic
| number = 3108
| date = June 27, 2025
| title = Laser Danger
| image = laser_danger_2x.png
| imagesize = 684x272px
| noexpand = true
| titletext = To combat the threat, many airlines are installing wing-mounted spray bottles.
}}

==Explanation==
Shining a laser at a plane is a [https://www.faa.gov/about/initiatives/lasers federal crime] in the US, and similarly forbidden in many other countries. A {{What If|13|sufficiently powerful}} laser can disorient, distract and/or blind the pilot operating the aircraft. This can prove particularly dangerous to the safety of the aircraft and its occupants during take-off and landing, when planes are likely to have altitudes and orientations particularly susceptible to laser interference, and are phases that are already hazardous periods of flight. This 'use' of lasers was previously discussed in [[3030: Lasering Incidents]] and [[2481: 1991 and 2021]].

Megan claims that there's another reason why lasering a plane is illegal: to avoid provoking cats into leaping at them. Cats are known to [[729: Laser Pointer|chase and jump onto]] the dots created by laser pointers. Cats also prey on birds, with estimates of 1.3 to 3.7 billion birds killed each year.{{actual citation needed}} Of course, a cat would be unable to jump to the height of a flying plane.{{Citation needed}} If the cat were able to reach the plane, it would find itself hilariously outsized, though colliding with the plane mid-air could cause damage akin to a bird strike (e.g. shattered windshield or engine failure). The cat in the image is similar in size to the plane and thus could do significant damage. It is unclear whether the cat is unusually large or the plane is a model aircraft. A similar joke was used in the title text of [[1463: Altitude]].

The laser is shown in green, which have become more popular in recent decades as they offer the highest power for the lowest cost and are most frequently the type used in aviation-related incidents.

The title text alludes to the fact that many cats do not like getting wet, and one of the methods people use to discourage them from a place or activity that is unwanted is to use spray bottles to wet their fur. The spray bottle might also emit a hissing sound, which cats associate with other cats threatening them. The "wing-mounted spray bottles" on aircraft could be a reference to fuel dump tubes, which spray out fuel to lighten the aircraft, commonly used before emergency landings (especially soon after take-off, when a nearly full load of fuel is now more trouble than it should have been). To combat actual physical threats to aircraft in real life, El Al (the Israeli national airline) and government aircraft {{w|Air Force One|used by heads of state}} often have various {{w|Flare (countermeasure)|countermeasures}} installed.

==Transcript==
: Megan: Shining laser pointers at planes is a federal crime. It's incredibly dangerous.
: Cueball: Oh, because it can blind the pilot?
: Megan: That's one reason...

: [A plane is shown, with a green laser pointer aimed at it.]

: [The laser disappears. A cat, approximately the same size as the plane, pounces on the plane and sends it tumbling.]

{{comic discussion}}<noinclude>

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Aviation]]
[[Category:Cats]]
[[Category:Comics with color]]

3246: Speedrun

2026-05-18T00:28:16Z

2603:6011:1F0:2A40:40CE:4E81:F3D4:9FA9: /* Explanation */

{{comic
| number = 3246
| date = May 15, 2026
| title = Speedrun
| image = speedrun_2x.png
| imagesize = 288x343px
| noexpand = true
| titletext = Usain Bolt holds the world record in the 100 meter speedrun.
}}

==Explanation==
{{incomplete|This page was created by a SPEEDRUNNING BOT. Don't remove this notice too soon.}}
{{w|Speedrunning}} is the sport of completing a {{w|video game}} or achieve a goal within the game(for example: completing the main story) as fast as possible.
This comic shows Cueball sitting at a desk complaining that his speedrun got deleted off of [https://www.speedrun.com/ Speedrun.com], which is a popular leaderboard aggregator for speedrunners.

A {{w|tool-assisted speedrun}} (or TAS for short) is a type of speedrun where inputs can be manipulated after the fact to perfect a run. While this tool is mostly for experimenting with new strategies or finding areas where a time can be optimized, it is possible to cheat a run by passing off a tool-assisted run as a normal speedrun. ''{{w|Lateralus}}'' and ''{{w|Ænima}}'' are albums by the band {{w|Tool (band)|Tool}}. This comic makes use of a pun, where rather than using third party tools to assist him in beating a video game as quickly as possible, Cueball is getting "assistance" from the rock band Tool in the form of background music to help him concentrate, which would be considered 'third-party' if Tool was not directly related to the game. In real life, a speedrun would be unlikely to be removed based on the music one is listening to while completing it, though it may be considered similar to using a {{w|metronome}}, a [https://www.reddit.com/r/speedrun/s/ODqJcAWcKg controversial topic] due to the fact that a metronome could be very useful if the game one is playing requires some sort of rhythm or precision. The comic could also be referencing Alex Honnold’s ascent of the Taipei 101 tower, during which he listened to Tool. The comic was posted 25 years after the ''{{w|Lateralus}}'' album was released.

The title text is a pun on the word "speedrun". {{w|Usain Bolt}}'s 100-meter dash record is a world-record "speedrun" in the sense that it is literally a speedy run and also an attempt by someone to complete a task as fast as possible. It is very common for internet personalities to say they are 'speedrunning' when they are doing a task quickly, even when completely unrelated to gaming (e.g. [https://www.youtube.com/shorts/sqjRfF2cYoE speedrunning petting a cat]). The notion of such a record being classified as a legitimate speedrun isn't farfetched as Speedrun.com has some leaderboards for [https://www.speedrun.com/series/IRL In Real Life] records. The use of "speedrun" to refer to an actual fast run may be considered to be a case of [[3123: Canon]].

In road races like {{w|marathon}}s, wearing technical devices is severely limited. For example, they are not allowed to transmit any data. Therefore, speedrunning a marathon while listening to Lateralus and/or Ænima is prohibited - at least in serious competitions, where athletes are checked for wearing earphones, while amateurs get some leeway and can even carry their mobile phones.

It is possible that speedrunning was on his mind due to the recent social media trend of {{w|Scientology speedrunning}}, in which someone attempts to get as deep as they can into a building belonging to the {{w|Church of Scientology}} before being kicked out. Because of this trend, the concept of speedrunning has been on many people's minds, regardless of whether or not they participate in the trend.

[[Randall]] has referred to bizarre speedruns before in [[3148|this comic here.]]

==Transcript==

:[Cueball is sitting at a desk with a laptop, typing on it. Megan is standing behind him.]
:Cueball: Aw man, Speedrun.com removed my world record just because I listened to Lateralus and Ænima to get in the flow.
:Megan: Oh, a copyright thing?
:Cueball: No, they don't allow Tool-assisted speedruns.

{{comic discussion}}<noinclude>

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Video games]]
[[Category:Music]]
[[Category:Puns]]

3148: 100% All Achievements

2026-05-18T00:24:26Z

2603:6011:1F0:2A40:40CE:4E81:F3D4:9FA9: /* Explanation */

{{comic
| number = 3148
| date = September 29, 2025
| title = 100% All Achievements
| image = 100_all_achievements_2x.png
| imagesize = 271x475px
| noexpand = true
| titletext = I'm trying to share my footage of the full run to prove it's not tool-assisted, but the uploader has problems with video lengths of more than a decade.
}}

==Explanation==
100% All Achievements is a category of {{w|Speedrunning|video game speedruns}} where the goal is to do everything possible in the game or complete the story of the game, as fast as possible. Many games have a progress bar to track completion of the game, making the "100%" criterion officially defined. "Achievements," also known as "trophies" for games on Sony-branded consoles, are another way to track accomplishments, either tracked within the game itself or through the storefront used to purchase the game such as the Microsoft Store. In some cases (particularly if external achievements are also tracked within the game itself) a 100% speedrun requires the player to collect every achievement. Sometimes, however, achievements are tracked separately from in-game completion, and thus are irrelevant to a 100% run. Some games include external achievements for spending a given amount of time playing the game (eg. An achievement for playing the game for 100 hours) which, if required, would defeat the point of trying to complete the game quickly. The phrasing here implies that Cueball’s university is not one such example, and that any external achievements must be completed for Cueball to consider his run complete.

[[Cueball]] is attempting a 100% All Achievements run for his university, which is a ridiculous pursuit for several reasons. Even though 100% runs for video games can take very long (up to [https://www.speedrun.com/baten_kaitos_eternal_wings_and_the_lost_ocean?h=100&x=mke7v926 two weeks]), they don't even come close to the amount of time needed to complete a single university major, let alone every class. This would be prohibitively expensive for most people due to the high cost of university attendance. Moreover, "All Achievements" is vaguely defined in this scenario, and the "achievements" possible at a university will change as courses, academic tracks, and degrees offered change. In contrast, even if the possible achievements in a video game change as updates and downloadable content are released, it is possible to specify a particular version of the game used for the speedrun. The university is clearly upset with this choice of action, and demands that he stop it and graduate. This may be because they doubt his ability to retain this information, perhaps because they simply cannot get as much tuition from one man, or possibly because they feel he is making a mockery of the institution.

“All achievements” could simply refer to completing all courses and degree programs, but achievements in video games often involve optional paths or accomplishments unrelated to the main game progress. The equivalent for a university speedrun may mean Cueball also must participate in extracurricular activities such as clubs and other university-associated events, even if they do not directly contribute to his eventual graduation requirements. Depending on how involved the university is, this may add significant challenge and time to the speedrun. If the speedrun requires Cueball to participate in, say, several university sporting leagues at once, the time and effort spent over the course of training, practice, recovery, and event matches (possibly requiring significant travel) may even outweigh his already Herculean academic efforts.

While this might sound ludicrous, "{{w|perpetual students}}" are people who spend long periods at a university. {{w|Michael Nicholson (academic)|Michael Nicholson}}, the world record holder, completed 30 majors between before 1964 and 2016.

Gen-ed, which Cueball says he had completed all of in 2010, refers to {{w|Curriculum#Core_curriculum|general education courses}}. This usually means either:
(1) a set of classes, or at least categories of classes (such as literature, history, science, foreign language, etc.), that must be taken by all students, regardless of major; or
(2) classes that have few prerequisites, intended to be taken by students in other disciplines or by people not in university programs at all, to broaden their education (for example, a course in general science for arts students). It is common for a university program to require a student to take several courses that are somewhat related to their nominal preferred specialty in their first year, to provide a foundation for later studies and to permit some flexibility if the student's interests change. In some countries, some gen-ed courses are also included in programs of study so that students get at least a bit of exposure to unrelated disciplines. Many students aim to get these courses out of the way within their first one or two years, though some universities have more specific or long-term requirements (eg: requiring all students to take at least one lower-division and at least one upper-division humanities course) to ensure breadth through a student's undergrad career.

Classes at a university typically receive a code that combines the name of the field/discipline being taught with a two- or three-digit number (e.g., a course in anthropology might be ANTH 209). The leading digit typically provides information about how advanced a class is: lower division work might receive a 0 or 1, while upper division and graduate courses will receive higher numbers. Although there is no standardization across universities for which specific numbers equate to which course levels, the generally accepted baseline education given in any specific subject is usually associated with the number {{w|101 (number)#In_education|101}}, while classes in the 400s are usually taken in the 4th year of undergrad at most universities, and may provide credit towards graduate-level degrees.

In traditional speedrunning, a {{w|tool-assisted speedrun}} (mentioned in the title text) is one done with software such as a {{w|video game console emulator|video game emulator}} to record and then play back incredibly precise movements. These are typically used to show the theoretical upper limit of how quickly a game can be completed, even if the required techniques are beyond human capabilities (i.e. performing a long chain of optimal actions, flawlessly, without the need to replay or restart any stage). Particularly exceptional speedruns may rouse suspicion that they weren’t truly performed by a human, which is what Cueball is trying to quell. It is unclear how such tools might be applied to the pursuit of education, but Cueball may have meant using artificial intelligence or similar "cheats" to illegitimately complete his work. Unassisted speedruns are typically reviewed in full by a moderator of the speedrunning community for that game to ensure there truly were no tools involved. There is no known community for university speedrunning,{{Citation needed}} so no moderators will be able to review the years of footage to determine whether the speedrun was legitimate. Tool-assisted speedruns were later mentioned in [[3246: Speedrun]].

Most video-sharing services limit the length of uploaded videos, either by size or length, for a variety of reasons. A decade-long video file is almost certainly too big for any service: an hour of 720p-resolution video is about one gigabyte [[https://www.overcasthq.com/blog/how-big-are-video-files/ Overcast]], so a decade would be about 100 terabytes. The longest video ever to be hosted on YouTube is just under 25 days [[https://www.imdb.com/title/tt12095652/trivia/ IMDB]], under 1% of what Cueball wants. Such a video would require significant infrastructure support by the service for it to be allowed, not to mention presenting challenges to recording and storing it in the first place. Also, the moderators would spend much of their time watching the video. Assuming they watch 8 hours every day and there are 10 moderators splitting the video, we can calculate the days needed assuming it is about a decade. (10*365*24)/8/10 =87,600/8/10 = 1095. So, they need 1095 days, or about 3 years.

==Transcript==
:[Cueball, arms outstretched, is talking to White Hat.]
:Cueball: I finished all the gen-ed back in 2010, and I'm up to the 400-level courses in most departments.
:Cueball: But now one of my advisors is saying I "can't have more than 20 majors" and "need to graduate next year."
:Cueball: It's outrageous!

:[Caption below the panel:]
:My university is making it really hard to finish a 100% all achievements speedrun.

{{comic discussion}}<noinclude>
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring White Hat]]
[[Category:Video games]]

3234: Europa Missions

2026-05-16T16:52:51Z

2603:6011:1F0:2A40:40CE:4E81:F3D4:9FA9: /* Explanation */

{{comic
| number = 3234
| date = April 17, 2026
| title = Europa Missions
| image = europa_missions_2x.png
| imagesize = 515x274px
| noexpand = true
| titletext = Before resurfacing, they promise to inspect the ice for any evidence of hockey-playing life.
| wikidata = Q139738154
}}

==Explanation==
In recent years, multiple space agencies have sent spacecraft to observe Jupiter’s moon {{w|Europa (moon)|Europa}}. In part, this is because, according to {{w|NASA}}, the moon could be a candidate for life due to the presence of a subsurface ocean and (possibly) {{w|hydrothermal vents}}. The first two craft — the {{w|Europa Clipper}} and {{w|Jupiter Icy Moons Explorer}} (Juice), respectively — will investigate the ocean, topography and chemistry of the moon, to help in searching for signs of life. Europa's ocean is frozen on top — the whole surface being solid ice with no exposed liquid, except perhaps at the bottom of any transient deep crevasses — which is why it described as a "subsurface ocean". (Randell has talked about the [[3011|Europa Clipper]] before.)

A {{w|Zamboni}} is a vehicle that is meant to quickly resurface ice rinks that have been worn down — not a scientific mission or a transport for other scientific missions. The comic describes a non-existent spacecraft known as the ''Zamboni Voyager'', operated by the {{w|National Hockey League}} (NHL). The spacecraft is carrying a Zamboni because the NHL is trying to 'expand the league'. Normally, expanding a sports league would involve, at the very least, forming a new team in a city which did not have one. In this scenario, they appear to be more literally trying to expand the available space for play, by resurfacing Europa to make it viable for hockey-playing. (Although Europa is the {{w|Europa (moon)#Surface environment|smoothest known body}} in the solar system, it's probably not smooth enough for playing hockey.) Hockey in reduced gravity — Europa's gravity is less than 1/7 that of Earth — would be {{What If|124|an interesting idea}}. However, it would be ridiculous to, even if the plan succeeded, ferry spaceships to and from Europa simply to get hockey players and fans over just to see a game of Hockey.{{Citation needed}}

The title text talks about finding hockey-playing life on Europa, which would be unlikely, as any life on Europa would exist underwater, where it's difficult to play hockey.{{cn}} In addition, any conceivable culture(s) there would almost certainly be extremely different from Earth's, so even if the lifeforms on Europa do have entertainment similar to sports, it's unlikely that they have even {{w|Convergent evolution|remotely similar}} rules or equipment. If, though, there were intelligent non-hockey-playing life on Europa, the NHL may consider them fair game as a virgin market for their product.

On top of that, making a spacecraft to send a Zamboni to Europa would be very difficult, as 14,000 m/s of delta-v (a measure of the total change in velocity required to transfer between orbital or 'ground' locations) is needed. With a typical Zamboni weighing five tons, a very heavy rocket would be needed. Europa clipper weighs about six tons, which is comparable to a heavy Zamboni. That particular spacecraft will not perform an orbital insertion or a landing, but only a fly-by to save fuel. Even then, it needs a fully expendable Falcon Heavy, the largest commercially available rocket (as of the comic being published), to achieve the fly-by. A landing would need much more available delta-v for the final approach.

If whoever was talking (e.g. NASA) tried to stop them, something like an SLS launch (which is ludicrously expensive on top of not being commercially available) with more payload capacity may not even be possible. SpaceX’s Starship might be viable in the future, but again, if an agency tried to stop them they would likely not get a contract. On top of that, many of the critical technologies for Starship are ''not yet'' (good luck, SpaceX) available. Even with an SLS/Starship, successfully achieving a propulsive landing would be very difficult, as demonstrated by {{w|IM-1}} and {{w|IM-2}}, which both failed to land on our own Moon (and more landers from other agencies). A normal Zamboni is probably not hardened against Jupiter’s intense radiation environment and, unless adapted for robotic remote control, the life support system for the operator would greatly increase the total weight of the mission. Also, the water in a Zamboni would freeze long before it was applied.

==Transcript==
:[Cueball's upper body is shown; he is in front of an image of a spacecraft.]
:Cueball: There are now three spacecraft headed to Europa:
:Cueball: NASA's ''Europa Clipper'', which investigate Europa's subsurface ocean,

:[In a longer shot, Cueball, Ponytail, and Hairy are all shown standing in front of another spacecraft image, with Cueball gesturing at it.]
:Cueball: ESA's ''Jupiter Icy Moons Explorer'', which will study the topography and chemistry of Europa and the other moons,

:[Another closeup on Cueball, who is in front of an image of a Zamboni with a firing rocket nozzle on its bottom.]
:Cueball: And the NHL's ''Zamboni Voyager'', which plans to resurface Europa.
:Voice out of frame: Oh no.
:Cueball: We tried to stop them, but the league is set on an expansion.

==Trivia==
* The [https://www.explainxkcd.com/wiki/images/archive/f/fd/20260418170145%21europa_missions_2x.png original version of the comic] incorrectly referred to the "Jupiter Icy Moons ''Orbiter''" rather than "Jupiter Icy Moons ''Explorer''."

* This comic was created at around the time of the start of the season's NHL playoffs.

* This comic was posted 10 days after April 7, 2026, a pivotal date in ''{{w|17776}}'' — a space-probe related and sports-related webcomic which features Jupiter Icy Moons Explorer ("Juice"), the space probe mentioned in this comic, as a main character. (While the webcomic began in 2017, it received another wave of popularity in the lead-up to April 7, 2026, the date on which humans stopped being born (and essentially stopped dying and aging) within the story's fiction.)

* Kerbal Space Program is a great way to learn the basics of orbital mechanics.

{{comic discussion}}<noinclude>

[[Category:Comics edited after their publication]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairy]]
[[Category:Space probes]]
[[Category:Sport]]

2973: Ferris Wheels

2026-05-16T15:29:41Z

2603:6011:1F0:2A40:40CE:4E81:F3D4:9FA9: /* Explanation */

{{comic
| number = 2973
| date = August 16, 2024
| title = Ferris Wheels
| image = ferris_wheels_2x.png
| imagesize = 624x280px
| noexpand = true
| titletext = They left the belt drive in place but switched which wheel was powered, so people could choose between a regular ride, a long ride, and a REALLY long ride.
}}

==Explanation==
This comic depicts an attempted connection of three {{w|Ferris wheel}}s using a {{w|Belt (mechanical)|mechanical belt drive}}, a system used to transfer motion between rotating shafts such as what these become. By connecting the belt to different circumferences, the relative motion is geared up or down. If the belt passes around the circumference of one wheel and is connected around the hub of another, the latter will rotate significantly faster. In this case, the second wheel's circumference is in turn connected to a third wheel's hub, resulting in even greater rotational velocity. However, this setup is mechanically unsound and possibly dangerous,{{Citation needed}} as Ferris wheels are not intended to be connected in this way. As shown, the first wheel on the left is running at a normal speed, while the other two are rotating increasingly fast, leading to a {{w|G-force#Human tolerance|potentially hazardous}} situation where passengers are flung around to various extents.

Ferris wheels can vary widely in size and speed of rotation, but for illustration, let us assume a diameter of about 200 feet (60 m) and a pretty sedate speed of around 10 minutes per full rotation. The apparent ratio between the connected wheels in the comic is approximately 12.5:1, meaning the motion is significantly sped up as it’s transferred. The second Ferris wheel, driven by the first, could spin at around 1.3 rpm, with passengers moving at 9 mph (14 km/h), giving a more exciting ride, but not inherently dangerous. However, when this motion is further transferred to the third Ferris wheel, it could spin at a possible 16 rpm, with passengers traveling at over 110 mph (180 km/h), subjecting them to around 8 Gs of force. Randall has previously explored the limits of the human body's tolerance for acceleration in ''{{What If|116|What If # 116 "No Rules NASCAR"}}''. Additionally, if a Ferris wheel span at 110 mph (180 km/h) it would itself be just as dangerous even without any riders. However, since the motor for the first wheel would have been selected merely to drive one wheel, it's unlikely it would be able to power the other two wheels moving at these increased speeds — if it moved at all, all three would probably start to move quite slowly, with potential damage to the motor before any friction limitations and other mechanical failures kicked in.

In the caption [[Randall]] says that he was fired for this ill-advised modification, highlighting the impracticality and dangers of the idea. A cruise line also fired the respective narrator due to an unsound engineering proposal earlier in [[2935: Ocean Loop]].

The title text imagines the consequences of leaving the belt drive system in place but switching which wheel is powered. If the most extreme wheel (the third one on the right) is powered, the gearing would be reversed, making for a possibly pleasant and normal ride on the right-hand wheel, but rendering the experiences of the riders on the other two wheels far too slow for an enjoyable carnival ride. One revolution of the center wheel might take two hours and five minutes, while the left wheel would take around a little more than a day per revolution.    This exaggerates the impracticality and unintended effects of using a belt drive system to link up Ferris wheels, illustrating how such an idea would lead to absurdly varied ride experiences.

==Transcript==
:[Three Ferris wheels are shown side by side, with some people stood on the ground for scale. Each of the first two wheels has a belt connecting its circumference to the axle of the wheel to its right. "Agitrons" indicate that the middle wheel is turning notably faster than the left wheel, with the gondolas seen to be rocking significantly at all points round the wheel. The spokes of the right wheel are completely replaced by "motion lines", indicating that the the right wheel is turning the fastest of all. All its gondolas are hanging outwards against centripetal force, interspersed with their own motion lines.]

:[Caption below the panel:]
:The county fair fired me for adding a belt drive to the Ferris wheels.

==Trivia==
The first (slowest) wheel can be seen to notably lack a 'spoke' at approximately the five o'clock position, supporting the point where its respective passenger seating is hung. Clearly, however, the wheel design is strong enough to withstand much greater forces in the other two versions of the wheel (which appears to be complete in the case of the second, though the thin spokes are only seen as blurs in the third wheel) suggesting that there may not be significant danger from this omission. It does not bode well, however, for general {{w|Occupational Safety and Health Administration|OSHA compliance}} in how they erect/maintain the rides, even before the belt-drive idea added its own issues.

{{comic discussion}}

[[Category:Physics]]
[[Category:Engineering]]