ABCD
Exclusion Principle

Fermions are weird about each other in a standoffish way. Integer-spin particles are weird about each other in a 'stand uncomfortably close while talking' kind of way.
Linear Sort

The best case is O(n), and the worst case is that someone checks why.
Phase Change

Even when you try to make nice, smooth ice cubes in a freezer, sometimes one of them will shoot out a random ice spike, which physicists ascribe to kiki conservation.
METAR

In the aviation world, they don't use AM/PM times. Instead, all times are assumed to be AM unless they're labeled NOTAM.
The Maritime Approximation

It works because a nautical mile is based on a degree of latitude, and the Earth (e) is a circle.
Making Tea

No, of course we don't microwave the mug WITH the teabag in it. We microwave the teabag separately.
Seismologists

And even when they're not distracted, they usually get kicked out for illegal under-the-net 'subduction spikes'.
Infinite Armada Chess

Stockfish 16 suggests the unconventional opening 1. RuntimeError: Out of bounds memory access
Advent Calendar Advent Calendar

The growth rate of items per day may may seem absurd, but it's actually much less than the acceleration in the 12 Days of Christmas song.
Second Stage

Hmm, they won't do in-flight delivery, so let's order a new first and second stage to our emergency landing site and then try to touch down on top of them to save time.
Neutrino Modem

Our sysadmin accidentally won a Nobel Prize while trying to debug neutrino oscillation error correction.
Cold Air

We also should really have checked that the old water tower was disconnected from the water system before we started filling it with compressed air.
D Combinatorics

Look, you can't complain about this after giving us so many scenarios involving N locked chests and M unlabeled keys.
Arizona Chess

Sometimes, you have to sacrifice pieces to gain the advantage. Sometimes, to advance ... you have to fall back.
Kedging Cannon

The real key was inventing the windmill-powered winch.
The Future of Orion

Dinosaur Cosmics
Europa Clipper

They had BETTER make this a sample return mission.
Geometriphylogenetics

There's a maximum likelihood that I'm doing phylogenetics wrong.
Number Shortage

"10 minutes ago we were down to only 2 0s!" "How many do we have now?" "I ... don't know!!"
Proterozoic Rocks

These rocks are from a time before eyes, brains, and bones, pieces of a land warmed by an unseen sun.
Probabilistic Uncertainty

"One popular strategy is to enter an emotional spiral. Could that be the right approach? We contacted several researchers who are experts in emotional spirals to ask them, but none of them were in a state to speak with us."
Demons

Though they do appreciate how much he improved the heating system for the flame pit.
Disposal

We were disappointed that the rocket didn't make a THOOOONK noise when it went into the tube, but we're setting up big loudspeakers for future launches to add the sound effect.
Wells

You do have to be careful, though--sometimes, instead of water, you hit this free fuel that you can sell for a lot of money instead.
Sandwich Helix

The number one rule of string manipulation is that you’ve got to specify your encodings.
RNAWorld

Disney lore: Canonically, because of how Elsa's abiogenesis powers work, Olaf is an RNA-only organism.
Temperature Scales

In my new scale, °X, 0 is Earths' record lowest surface temperature, 50 is the global average, and 100 is the record highest, with a linear scale between each point and adjustment every year as needed.
Experimental Astrophysics

Our experiment will be expensive, but we believe it will produce important spin-offs, especially if we manage to hit the sun from the right angle.
Bad Map Projection: The United Stralia

This projection distorts both area and direction, but preserves Melbourne.
Ravioli-Shaped Objects

It's a real accomplishment to mess up a ravioli recipe badly enough that the resulting incident touches all four quadrants of the NFPA hazard diamond.
Solar Protons

If any of you want to meet some cool local oxygen atoms, I can introduce you!
CIDABM

There's a heated debate over whether the big island of Tierra del Fuego should qualify for membership.
University Commas

The distinctive 'UCLA comma' and 'Michigan comma' are a long string of commas at the start and end of the sentence respectively.
Númenor Margaritaville

I see white shores, and beyond it, a far green country under a tequila sunrise.
Ingredients

Add main-belt asteroids to taste.
UK Coal

The Watership Down rabbits removed an additional 0.1 nanometers constructing their warren, although that was mostly soil. British rabbits have historically mined very little coal; the sole rabbit-run coal plant was shut down in the 1990s.
Beamsplitters

Under quantum tax law, photons sent through a beamsplitter don't actually choose which path they took, or incur a tax burden, until their wavefunction collapses when the power is sold.
Late Cenozoic

Our nucleic acid recovery techinques found a great deal of homo sapiens DNA incorporated into the fossils, particularly the ones containing high levels of resin, leading to the theory that these dinosaurs preyed on the once-dominant primates.
Physics Lab Thermostat

Hopefully the HVAC people set it to only affect the AIR in the room.
Maslow's Pyramid

The local police, building inspector, and fire marshal are all contesting my 'safety' assertion, or would be if they could reach me past all the traps.
Tectonic Surfing

The worst is when you wipe out in the barrel and you're trapped for several million years until erosion frees you.
Every Scientific Field

Conveniently for everyone, it turns out that dark energy is produced by subterranean parasitoid wasps.
Craters

It's annoying that the Nastapoka Arc isn't a meteor impact crater, but I truly believe that--with enough time, effort, and determination--we could make it one.
Asteroid News

Their calculations show it will 'pass within the distance of the moon' but that it 'will not hit the moon, so what's the point?'
Monocaster

My competitors say the tiny single tiny caster is unsafe, unstable, and offers no advantages over traditional designs, to which I say: wow, why are you guys so mean? I thought we were friends!
Water Filtration

You'd think the most expensive part would be the quark-gluon plasma chamber, but it's actually usually the tube to the top of the atmosphere to carry the cosmic rays down.
Slingshots

In my reboot, Dennis the Menace was just trying to send Mr. Wilson a nice comet, but accidentally wiped out his dinosaur garden.
Lava Lakes

Hey, golf balls float on lava, so this should make recovering them from the hazards easier.
Sky Alarm

During the day it also activates for neat clouds and pretty sunsets.
Stranded

At least they're not alone down there.
Three Kinds of Research

The secret fourth kind is 'we applied a standard theory to their map of every tree and got some suspicious results.'
Time Traveler Causes of Death

Many a hungry time traveler has Googled 'trilobites shellfish allergy' only to find their carrier had no coverage in the Ordovician.
Classical Periodic Table

Personally I think mercury is more of a 'wet earth' hybrid element.
Storage Tanks

We're considering installing a pressurization system to keep the tanks at constant pressure solely to deter them.
Ferris Wheels

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.
Helium Synthesis

Our lawyers were worried because it turns out the company inherits its debt from the parent universe, but luckily cosmic inflation reduced it to nearly zero.
Celestial Event

If we can get a brood of 13-year cicadas going, we might have a chance at making this happen before the oceans evaporate under the expanding sun.
Meteor Shower PSA

If you hold the meteor too long, it may imprint on you and form a contact binary, making reintroduction to space difficult.
Vice President First Names
![[Political pundit on the ScrabbleTV News channel] "After four years of defying orthographic pressure, Joe ceded the top of the ticket to Kamala, who--after considering Josh, Mark, Andy, Roy, and Pete--picked Tim."](https://imgs.xkcd.com/comics/vice_president_first_names.png)
[Political pundit on the ScrabbleTV News channel] "After four years of defying orthographic pressure, Joe ceded the top of the ticket to Kamala, who--after considering Josh, Mark, Andy, Roy, and Pete--picked Tim."
University Age

This only makes it more urgent that we adopt my roadmap for the next 10 years, which should put us solidly in the lead.
Matter

He was the first person to land a 900, which is especially impressive because pulling off a half-integer spin requires obeying Fermi-Dirac statistics.
Exam Numbers

Calligraphy exam: Write down the number 37, spelled out, nicely.
Chili Tornado Quake

Buildings constructed from softer materials were damaged by chili pepper impacts to the storm's high Richter-Fujita-Scoville-Mohs hardness rating.
Olympic Sports

Thankfully for everyone involved, the Winter Olympics officials spotted me and managed to stop me before I got to the ski jump.
House Inputs and Outputs

People think power over ethernet is so great, and yet when I try to do water over ethernet everyone yells at me.
President Venn Diagram

Hard to imagine political rhetoric more microtargeted at me than 'I love Venn diagrams. I really do, I love Venn diagrams. It's just something about those three circles.'
CrowdStrike

We were going to try swordfighting, but all my compiling is on hold.
Organ Meanings

IMO the thymus is one of the coolest organs and we should really use it in metaphors more.
Beam of Light

Einstein's theories solved a longstanding mystery about Mercury: Why it gets so hot. "It's because," he pointed out, "the sun is right there."
Hatchery

Anadromous fish are more vulnerable in rivers, since the lack of salt means you can quickly crack passwords using rainbow trout tables.
A Crossword Puzzle
![Hint: If you ever encounter this puzzle in a crossword app, just [term for someone with a competitive and high-achieving personality].](https://imgs.xkcd.com/comics/a_crossword_puzzle.png)
Hint: If you ever encounter this puzzle in a crossword app, just [term for someone with a competitive and high-achieving personality].
Number Line Branch

Attention all passengers: This is an express sequence to infinity. If your stop is not a power of two, please disembark now.
Pole Vault

Ugh, and we JUST went through this yesterday with javelin.
Bracket Symbols

’"‘”’" means "I edited this text on both my phone and my laptop before sending it"
Alien Theories

They originally came here to try to investigate our chemtrail technology, and got increasingly frustrated when all their samples turned out to just be water ice with trace amounts of jet exhaust.
Routine Maintenance

The worst was the time they accidentally held the can upside down and froze all the Earth's magma chambers solid.
Bad Map Projection: Exterior Kansas

Although Kansas is widely thought to contain the geographic center of the contiguous 48 states, topologists now believe that it's actually their outer edge.
Situation

We're right under the flight path for the scheduled orbital launch, but don't worry--it's too cold out for the rockets to operate safely, so I'm sure they'll postpone.
Network Configuration

If you repeatedly rerun the development of technological civilization, it turns out that for some reason the only constant is that there is always a networking utility called 'netcat', though it does a different thing in each one.
Electric vs Gas

An idling gas engine may be annoyingly loud, but that's the price you pay for having WAY less torque available at a standstill.
Pascal's Wager Triangle

In contrast to Pascal's Wager Triangle, Pascal's Triangle Wager argues that maybe God wants you to draw a triangle of numbers where each one is the sum of the two numbers above it, so you probably should, just in case.
1.2 Kilofives

'Oh yeah? Give me 50 milliscore reasons why I should stop.'
Broken Model

In addition to eating foxes, rabbits can eat grass. The grass also eats foxes. Our equations chart the contours of Fox Hell.
Magnet Fishing

The ten-way tie was judged a ten-way tie, so no one won the grand prize, a rare fishing monopole.
Unsolved Chemistry Problems

I'm an H⁺ denier, in that I refuse to consider loose protons to be real hydrogen, so I personally believe it stands for 'pretend'.
Fluid Speech

Thank you to linguist Gretchen McCulloch for teaching me about phonetic assimilation, and for teaching me that if you stand around in public reading texts from a linguist and murmuring example phrases to yourself, people will eventually ask if you're okay.
Cell Organelles

It's believed that Golgi was originally an independent organism who was eventually absorbed into our cells, where he began work on his Apparatus.
Modes of Transportation

My bold criticism might anger the hot air balloon people, which would be a real concern if any of them lived along a very narrow line directly upwind of me.
Complexity Analysis

PERPETUALLY OPTIMISTIC CASE: Early in the execution, our research group makes a breakthrough on proving P=NP.
Local Group

Cosmologists estimate the spaghetti strand to be about 200 septillion calories, though it could be higher depending on the nutritional value of dark matter.
Room Code

Sorry to make you memorize this random string of digits. If it helps, it can also double as a mnemonic for remembering your young relatives' birthdays, if they happened to have been born on February 5th, 2018.
Exponential Growth

Karpov's construction of a series of increasingly large rice cookers led to a protracted deadlock, but exponential growth won in the end.
Ocean Loop

I can't believe they wouldn't even let me hold a vote among the passengers about whether to try the loop.
Bloom Filter

Sometimes, you can tell Bloom filters are the wrong tool for the job, but when they're the right one you can never be sure.
Elementary Physics Paths

==COSMOLOGY==> 'Uhhh ... how sure are we that everything is made of these?'
Driving PSA

This PSA brought to you by several would-be assassins who tried to wave me in front of speeding cars in the last month and who will have to try harder next time.
Chasing

Certain hybrid events can only happen in certain locations where all the conditions are present; chasers flock to the area in and around Kansas known as tumbleweed-colliding-with-possum alley.
Google Solar Cycle

From Google Trends, it looks like the lag between people Googling cocktail recipes and 'hangover cure' is 14 hours.
Good and Bad Ideas

While it seemed like a fun prank at the time, I realize my prank fire extinguishers full of leaded gasoline were a mistake.
Software Testing Day

The company tried to document how often employees were celebrating Software Testing Day, but their recordkeeping system kept mysteriously crashing.