2312: mbmbam

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mbmbam

Title text: Hello and welcome to Millibar Millibarn Attometer, an advice show for the Planck era.

Explanation

In part, this comic is an homage to the referenced podcast, My Brother, My Brother, and Me, which often features rapid garden-path conversations and puns and double entendres that are at once groan-worthy and delightfully witty. "MBMBAM" is an acryonym of "My Brother, My Brother, And Me".

The millibar is a metric unit of pressure (force per unit area), equal to a thousandth of a bar, or 100 Pa. It is slightly less than one-thousandth of sea-level atmospheric pressure on Earth (a standard atmosphere is 1013.25 millibar).

The millibarn is a metric unit of area, equal to a thousandth of a barn (a humorously-named unit approximately equal to the cross-sectional area of a uranium nucleus), or 10^-31 m^2 or 10^-27 cm^2. Both units would theoretically have the symbol mb. Hence mbmb (the pressure unit multiplied by the area unit) would be a unit of force. This can be seen by applying dimensional analysis; pressure x area = (force/area) x area = force. Nobody in the comic strip discusses the magnitude of this force, but it would be 100 Pa x 10^-31 m^2 = 10^-29 newtons = 10^-24 dynes, or about the weight of an electron under Earth's gravity.

am would be the symbol of an attometer, or 10^-18 meters. Multiply that to create the unit mbmbam, which would be a unit of energy. Specifically, it would be a unit of work: the energy expended to move an object. More dimensional analysis: force x distance = (work/distance) x distance = work. The actual value of 1 mbmbam is correctly calculated in the comic: 100 Pa x 10^-31 m^2 x 10^-18 m = 10^-47 joules = 10^-40 erg. White Hat dubs this unit "one podcast".

The final panel is an extended series of puns: 'rise' referring to physically moving upward as well as biologically growing (expanding and becoming lighter and softer) as yeasts do; 'foam' referring to both quantum foam (the fluctuation of spacetime on very small scales due to quantum mechanics) as well as the foam generated by yeast fermenting; 'unleavened dimensions' punning on the eleven dimensions of spacetime in string theory (actually, ten—M theory says eleven), while continuing to play on the theme of yeast--in this case, the universe is presumably flat because some of its dimensions lack the Planck yeast that would make them rise. White Hat appears to have managed to have caught onto these puns, much to his (extreme) dissatisfaction.

The example used in the comic of lifting a yeast cell 1 Planck length is one of many possible examples of 1 mbmbam of work. (The Planck length, approximately 1.6×10^−35 m or 1.6×10^−33 cm, is how far light travels in one unit of Planck time.) Another interpretation of 1 mbmbam would be the work necessary to pull two socially distancing (6 ft) SARS-CoV-2 virions apart by the thickness of a single strand of hair against the gravity they exert on each other.

The Planck Era (or Planck Epoch) referenced in the title text is the near infinitesimally short period covering the first 10^-43 s after the Big Bang, when energies were so high that the four fundamental forces were combined into one and ordinary subatomic particles didn't yet exist. It is unlikely there were advice shows during this era^{[citation needed]}, so this would likely be a modern nostalgia show for physicists. The title text is also a play on My Brother, My Brother and Me's tagline: An advice show for the modren [sic] era.

Transcript

[Cueball, Megan, and White Hat are standing next to each other, talking. Megan has her hands raised to the side, in a shrugging gesture.]

Megan: Odd how in physics "mb" is both millibars (pressure) and millibarns (area).

Megan: mbmb could mean millibar-millibarn, which is a unit of force, strangely.

White Hat: Units are weird.

[Same scene - Megan is now checking her phone. White Hat is raising his right index finger.]

Cueball: So what's mbmbam, the My-Brother-My-Brother-And Me unit?

Megan: Millibar-milliibarn-attometer, I guess? That'd be a unit of energy. 10^-47 Joules.

White Hat: "One podcast"

[Same scene in a frameless panel. Megan holds her phone to her side. White Hat has his arms raised to the side, excited.]

Cueball: 10^-47 sounds small.

Megan: Yeah, it's roughly the energy you'd need to lift one yeast cell by one Planck length in Earth's gravity.

White Hat: Planck yeast!

[Same scene in a regular panel. Megan has put away her phone, and has her right index finger raised. White Hat has his hands balled into fists, frustrated.]

Cueball: Doesn't Planck yeast rise on its own?

Megan: Yeah, that's what makes quantum foam. But data suggests our universe is flat.

Megan: String theory says it's because spacetime has unleavened dimensions.

White Hat: ...I hate you.

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Discussion

So ... what would the MMMbop unit be?

the power of love

This has gotta be at least the third or fourth time he's referenced MBMBaM. https://what-if.xkcd.com/155/ and https://xkcd.com/1836/ I know are two more examples, but there might be more. 162.158.107.13 00:54, 28 May 2020 (UTC)

Am I the only one thinking that mbmbam should be a unit of work, not energy? Force x distance... High school physics was a long time ago though. Philosophicles (talk) 03:15, 28 May 2020 (UTC)

Work is energy 172.69.62.154 05:28, 28 May 2020 (UTC)

The only difference could be absolute or relative energy, comparable to height above sea level vs. distance. Sebastian --141.101.69.193 06:36, 28 May 2020 (UTC)

My first instinct was "that´s a torque". But of course angles have no unit, and so torque and energy must have the same. --162.158.88.74 07:15, 28 May 2020 (UTC)

Please forgive my ignorance here: Is not a "degree" an angular unit?

ProphetZarquon (talk) 17:20, 29 May 2020 (UTC)

The concept that a plane angle is a dimensionless unit is a tenet of the International System of Units (SI). It works something like this. "Degrees" and "Radians" are two ways of expressing the same thing, the size of an angle. If you have an angle and you draw an arbitrary circle with the angle's vertex as the circle's center, so that your angle now "subtends" an arc of the circle, then the size of your angle in radians is defined to be the length of that arc divided by the length of the radius of the circle. The circumference of the whole circle has length 2π·r, so an angle of 360 degrees is also an angle of 2π·r/r radians. The numerator and the denominator are dimensionally both lengths. Dividing a length by a length yields a dimensionless quantity, i.e. one with no "unit". Consequently radians are dimensionless, and so are degrees. JohnB (talk) 19:52, 29 May 2020 (UTC)

Is my vision going blurry, or does that second panel say "milliibarn"? -- Peregrine (talk) 09:09, 28 May 2020 (UTC)

Yes, two 'i' before the barn. That must be a mistake. --108.162.229.192 10:28, 28 May 2020 (UTC) <-- Either that or it's milli - i*barn, going into imaginary dimensions. Cellocgw (talk) 11:58, 28 May 2020 (UTC)

MBMBaM's tagline is "an advice show* for the modern era", not an advice podcast.

Reminds me of how this symbol: "μ" means both "micro" (micrometer is μm.), and "friction" (frictional constant of X would be μ = X), and the population statistical average (the average acceleration due to gravity on the surface of earth is μ_gravity), and something like 20 other things according to this wikipedia article: https://en.wikipedia.org/wiki/Mu_(letter)#Use_as_symbol Tsumikiminiwa (talk) 15:53, 28 May 2020 (UTC)

Reminds me of the old joke: Several kittens have found their way up onto a sloping roof, which one falls off first? The one with the lowest μ... 162.158.155.218 21:52, 29 May 2020 (UTC)

"It's an advice show for the modren era", not modern. 162.158.79.15 19:35, 28 May 2020 (UTC)

I went ahead and removed the statement that "mbar" is more common than "mb," since the preferred abbreviation depends on the field. In atmospheric science, "mb" is nearly universal. 162.158.187.201 17:19, 28 May 2020 (UTC)

anyone following that podcast who can shed light on the arrangement of the dashes? why is there non between "and" and "me" but between all the other words? (my-brother-my-brother-and (how do I emphasize a space?) me) --Lupo (talk) 06:40, 29 May 2020 (UTC)

Can anyone please explain (to me) the role of white hat in this comic? He is not part of the conversation and just makes more or less random statements, concluding in "I hate you". What am I missing here? Bischoff (talk) 19:54, 2 June 2020 (UTC)

I really think that this comic would be better without White Hat in it. His actions do seem like a complete non-sequitar.

For most of the dialogue, Megan and Cueball are discussing some oddities of dimensional units and making puns, while White Hat struggles to keep up. His utterances can be seen as 1) True but lacking insight ("UNITS ARE WEIRD") 2) A valid pun but out by about 10^50 ("ONE PODCAST") 3) Freaking out because it is all too weird for him ("PLANCK YEAST!") 4) Final breakdown due to some very high level punning by Cueball and Megan ("...I HATE YOU")

In the last panel, Cueball and Megan link Planck yeast (not a thing) and unleavened (yeast-free) bread to several concepts in theoretical physics: Quantum foam, the curvature of space time, and M-theory. M-theory suggests that space-time has eleven ("unleavened") dimensions, and is described by Wikipedia (https://en.wikipedia.org/wiki/String_theory) as a unification of superstring theories. The five consistent versions of superstring theory apparently suggests that space-time has only ten dimensions, so this may be a rare error by Randall. Or I may just have misunderstood. --Paul Seed 21:34, 28 June 2020 (UTC)

What about millibuckets? PoolloverNathan^[talk]U•T•S•c 17:54, 24 September 2021 (UTC)

mbar

I cite wikipedia:

The unit's official symbol is bar; the earlier symbol b is now deprecated and conflicts with the use of b denoting the unit barn, but it is still encountered ...

I wonder since when, und who still uses *mb*, since I have never encountered that in my life. --162.158.88.92 04:05, 29 May 2020 (UTC)

never seen it either. But the comic doesn't state that it is common, just that it is possible. See also comment above on atmospheric science. --Lupo (talk) 06:40, 29 May 2020 (UTC)

Here's a link to a page with multiple uses of mb with the meaning millibarn. It's in the CRC Handbook of Chemistry and Physics (97th ed., 2016), a "comprehensive one-volume reference reasource for scientific research". JohnB (talk) 13:28, 29 May 2020 (UTC)

172.68.51.107 09:56, 11 January 2023 (UTC)

mb • mb [millibar times millibarn] is not mbmb - it is ubb [microbarbarn]. Such a gabing plot hole...

Wrong comic title?

The XKCD website shows the comic title as "MBMBaM" instead of "mbmbam"; should this be fixed? Adrmcr (talk) 21:40, 9 August 2024 (UTC)

It was created by the BOT of the day, which (from experience, but also checking some of the contemporary comics/local pages) should have taken exactly what it was called at the time of discovering its release.

If it needs a page move, it'd ideally also need a "comic details changed"-type note, perhaps even an appropriate category membership (there's one for comic images changing, which this wouldn't be, but ...without checking... not entirely sure if this kind of tweak has another). 172.70.85.63 00:00, 10 August 2024 (UTC)