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We have an explanation for all 3306 xkcd comics, the 21 extra comics, and everything xkcd-related.
Only 52 explanations (1.6%) are incomplete. Help us finish them!


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Accelerator Energies
Fans at Daytona always get extra excited when officials decide to introduce some antimatter cars circling the track in the opposite direction.
Title text: Fans at Daytona always get extra excited when officials decide to introduce some antimatter cars circling the track in the opposite direction.

    Explanation

    This comic compares the Daytona International Speedway, a track for car races, with various particle accelerators, in terms of their length and collision energy produced. This is not a particularly meaningful comparison, since the two are completely different things.[citation needed]

    eV stands for electronvolt, a non-SI unit of energy. It is typically used in particle physics, where exceedingly small and light particles are accelerated to exceedingly high velocities approaching the speed of light, thus boosting their energy; it is also sometimes used as a unit of mass through E = mc2, such as in 2186: Dark Matter and 2035: Dark Matter Candidates. Trying to increase the energy as much as possible to create collisions that allow us to probe ever deeper in subatomic physics leads to ever-larger machines, some having circumferences of dozens of kilometers, necessary because particles' energy losses are smaller with larger, gentler curves. This also makes accelerators far more expensive.

    Judging by collision energy alone, a race car is a far cheaper way to cause a collision than a particle accelerator. It also has a shorter track than the largest accelerators, though, beyond a certain point, this isn't hugely relevant to the collision speed. At first glance, it may seem remarkable that a simple raceway produces collisions with energies so much higher than those of the various particle colliders, by about 10 orders of magnitude. It is important to note that the comparison needs to take into account the masses of the colliding objects. A vehicle might have a mass of 1000 kg or more, with a current Generation 6 vehicle specified for a minimum operational mass of 1542 kg. The Large Hadron Collider operates on particles ranging from protons (1 atomic mass unit, 1.66 x 10-27 kg) to lead atom nuclei (204 to 208 AMUs, 3.388 x 10-25 to 3.45 x 10-25 kg). Race cars are thus more than 1027 times as massive as the particles accelerated by the LHC, and therefore have higher collision energies despite their much, much slower speeds. Particle colliders do, however, provide much higher energy-divided-by-mass values.

    Some particle accelerators have been designed for collisions between matter and antimatter, such as between electrons and positrons or protons and antiprotons. Introducing antimatter circling in the opposite direction allows more energy to be put into the collision products because the original particles are destroyed (at least in theory; with baryons, it is often the case that only some of the quarks/antiquarks annihilate), so the equivalent energy of their rest mass—and, more significantly, their remaining kinetic energy after the collision—does not detract from the energy budget available to create collision products. This does not matter as much as people think it does, but it could lead to audience excitement because of pure energy (light) that would be emitted.

    Introducing a hypothetical antimatter race car going in the wrong direction would not only result in even more carnage but in a huge explosion as well. The Hiroshima atomic blast released energy equivalent to less than a gram of matter, so a matter-antimatter annihilation of 1000-kg race cars would be more than a million times larger. The fact that you, a spectator in the stands, would not survive such an energy blast is typical of xkcd. Randall has also compared a race track with a particle accelerator before.

    Transcript

    [A scatter-plot graph. The Y axis is labeled "Collision Energy" and shows values from 1 eV to 1027 eV, marked at every 3rd order of magnitude, using SI prefixes up to 1 PeV, then switching to scientific notation from 1018 eV; the SI prefixes Eta, Zetta, Yotta and Ronna are not used for higher values. The X axis is labeled "Track Length" and shows values from 10 cm to 100 km, marked at every order of magnitude. Three of the datapoints lowest to the left on the graph are each labeled as "First Cyclotrons" and are numbered #1, #2, and #3 below. Based on manual fitting, the datapoints in the scatter plot are as follows, with the location and the label applied:]
    [Length of 0.28 metres, energy of 3.00E+04 electronvolts:] First Cyclotrons [first of three points pointed at by this label]
    [Length of 2.9 metres, energy of 3.00E+06 electronvolts:] First Cyclotrons [second of three points]
    [Length of 5.7 metres, energy of 9.50E+06 electronvolts:] First Cyclotrons [third of three points]
    [Length of 4.8 metres, energy of 2.80E+08 electronvolts:] ADA
    [Length of 54 metres, energy of 2.10E+09 electronvolts:] COSMOTRON
    [Length of 101 metres, energy of 1.10E+10 electronvolts:] BEVATRON
    [Length of 250 metres, energy of 3.50E+09 electronvolts:] BEPC-II
    [Length of 1460 metres, energy of 3.00E+10 electronvolts:] J-PARC
    [Length of 2500 metres, energy of 8.00E+09 electronvolts:] CEBAF
    [Length of 4300 metres, energy of 6.00E+10 electronvolts:] RHIC
    [Length of 4800 metres, energy of 4.70E+24 electronvolts:] Daytona Speedway
    [Length of 6200 metres, energy of 8.00E+11 electronvolts:] TEVATRON
    [Length of 17500 metres, energy of 1.20E+13 electronvolts:] Large Hadron Collider

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    Edit this week's pick!

    This Week's Explanation for Improvement

    As part of the Explanation Improvement Project, each week the community selects one older, stagnant, or otherwise neglected explanation to expand and polish together. This week's pick is comic 186: Console Lines, you can help us by editing its explanation!

    To get involved with the project, you can also nominate an explanation that you think should be improved, or vote on current nominations!

    Console Lines
    If I get a Wii, it will be the first game console I've owned.
    Title text: If I get a Wii, it will be the first game console I've owned.

      Explanation

      Welcome to This Week's Explanation for Improvement! Anyone is encouraged to help explain comic 186: Console Lines; click here to get started! If you are new to wiki editing, you can read our editing FAQ for guidance. Here are some suggestions for improving this explanation:

        Why are the Nintendo people more kind than the Sony/Microsoft people? Explain!
        Explain what a "Nintendo Wii" is for readers who have never heard of it.
        Explain the necessary historical context of when this comic was published.
        Why does Randall say that a Wii will be the first game console he will ever own? Are there other comics posted after this one where he says he owns a different console?
        Improve the explanation of the double meaning of "console" in the comic.
        Explain how the world is different now from November 2006.

      This comic relates to video game consoles. At the time this comic was published, there were three major competing products: the Playstation 3 by Sony, the Xbox 360 by Microsoft, and the Wii by Nintendo. The Wii was released on November 19, 2006, the day before this comic was published. When a game console gets released, fans are often seen queueing outside the stores or camping on the pavement in order to be among the first to get their hands on a console. The comic shows such a console camp and points out the differences between the fan communities. While the fans waiting in line for a Sony or Microsoft product are very rude, the Nintendo fans are apologetic and try to comfort (that is to say, console) those who arrived too late to obtain a package. The cliché that Nintendo fans are nicer and more polite may be attributed to the fact that the Wii is targeted at children and families with children, while the PS3 and the Xbox are targeted at the more "serious gamer" crowd.

      The comic may also contain a subtle pun on the fact that 'console' has two meanings. A game console (noun) is a device that allows you to play video games, taking control input from one or more users and displaying the progress of the game as video output. However, to console (verb) means to make someone feel better when they are upset, as those in the Wii queue are attempting to do for the latecomers.

      The title text primarily expresses Randall's distance from the console wars (he has never owned a game console before), but also indicates an inclination towards the Wii, which was known for its (at the time) innovative motion controls.

      Transcript

      Fans turning away latecomers to all-night game console campouts:
      [Two lines, presumably leading to video game stores, are shown, where the same two people just arrived, behind other people]
      [In the line labeled Sony/Microsoft:]
      [Cueball, Megan, and another Cueball are in line, while Cueball and Hairy are just outside of the line]
      Cueball: The line is full, asshole! Fuck off!
      [In the line labeled Nintendo:]
      [Cueball, a chair, another Cueball, a third Cueball, and Ponytail are in line, while Cueball and Hairy are just outside of the line]
      Cueball: I'm so sorry, all the consoles are spoken for.
      Cueball: Do ... do you want a hug?

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