2780: Physical Quantities

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Physical Quantities
The Hubble length is about 1.9 meters lying down; Edwin Hubble was a tall guy.
Title text: The Hubble length is about 1.9 meters lying down; Edwin Hubble was a tall guy.


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This comic plays on the name of various established physical definitions by simply taking them overly literally. Each one is treated as being a bodily measure of the scientist after which they are named, rather than describing/estimating the eponymous feature within the scientist's field of study. Interestingly, of the many units named for people, only one is actually a measurement of its namesake: the Smoot.

Hubble volume

In cosmology, a Hubble volume (named for the astronomer Edwin Hubble) is a spherical region of the observable universe. The Hubble volume is approximately equal to 1031 cubic light years (or about 1079 cubic meters). The value given in the comic is the estimated volume of Edwin Hubble's body. The mean volume of a human body is around 65L[1], but Edwin Hubble was a big guy (see title text) and likely had an above-average volume.

Schwarzschild radius

The Schwarzschild radius of a black hole refers to the event horizon: the radius beyond which light cannot escape. Curling up in a ball tends to reduce people's radii,[citation needed] while making them more spherical and easier to measure, so Karl Schwarzschild's is given as 0.34 m, corresponding to a black hole of about 40 times the mass of Earth.

Broca's area

Broca's area is a region of the brain whose functions are linked to speech. It is not a measurement of area in the sense of length times width. The measurement shown here purports to be the area of Paul Broca, which probably refers to the surface area of his body - about 1.7-1.8 m2 for a typical adult. This area was recently mentioned in the title text of 2732: Bursa of Fabricius.

Fermi temperature

The concept of Fermi Temperature is related to the Fermi Energy, a quantum value inherent to very cold substances. The temperature of an average human is about 37 degrees Celsius, so it makes sense that Enrico Fermi’s baseline body temperature was, likewise, 37 degrees Celsius. Since Fermi lived in the 20th century, and it may be possible to reference his medical records, this assertion is potentially testable, perhaps more readily than those made for the 19th-century persons named in this comic.

Planck length

Planck units are naturally-derived measurements invented by Max Planck; the Planck length (approximately 1.6×10-35 m) is one of the smallest meaningful distances. However, Randall measures the length of Max Planck, not the units. It is specifically when Planck was lying down (as to not decrease his height from a days exposure to gravity which may shorten a human by a centimeter or so, and also because lying down turns a human’s height into a length, as well as being a pun on the plank exercise, which is done in a horizontal position).

Hubble length (title text)

A Hubble length is 14.4 billion light years. This is a joke similar to the above play on the Planck length. The Hubble distance would be the distance between the Earth and the galaxies which are currently receding from us at the speed of light. The joke is that the Hubble length is 14 cm longer than the Planck length because Hubble was a tall man. Another joke by comparing these two are that these two distances are about as far from each other as possible on scales that make sense. The smallest distance to something on the order of the size of the visible universe.


Ambox notice.png This explanation may be incomplete or incorrect: Image outdated
If you can address this issue, please edit the page! Thanks.
[A centered header appears above a list of constant names and corresponding values, each item horizontally aligned to line up the gaps between the two.]
Reference Physical Quantities
Hubble volume: 96L
Schwarzchild radius: 0.34m (curled up)
Broca's area: 1.7m2
Fermi temperature: 37°C
Planck length: 1.76m (lying down)

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Planck Length here actually refers to the length of Planck himself. The same may apply to other names. 2659: Unreliable Connection (talk) 03:02, 25 May 2023 (UTC)

And here I was thinking it meant the length of Planck planking. Thisfox (talk) 22:00, 25 May 2023 (UTC)

I wonder if this is alluding to the Smoot, a unit of measure devised by MIT students to represent the height of Oliver R. Smoot. Probably worth a mention in the description nonetheless. Trimeta (talk) 03:45, 25 May 2023 (UTC)

Hawking radiation: ~100 W (through heat)

I'm pretty sure he loses most of his heat through conduction and convection. Radiation should be much smaller. DanielLC (talk) 06:24, 23 March 2024 (UTC)

Planking is a thing.https://en.m.wikipedia.org/wiki/Planking_(fad) One pretends that one is a board, or plank. Are some funny pics. The opposite of planking would be good god how? How can even a cat!?!! [Special:Contributions/|]] 06:26, 25 May 2023 (UTC)

Hubble length is 13.2 m. 10:30, 25 May 2023 (UTC)

The m³ unit for Broca's area is surely a typo, right? 14:55, 25 May 2023 (UTC)

That would be my guess. I sent a note to Randall to ask. BunsenH (talk) 21:24, 25 May 2023 (UTC)
The comic has been corrected to m2 now. ~underhat

Just a couple of others: 1 Watt is what it takes to invent the condensing steam engine and Euler's number doesn't exist, because he died before telephones were invented. 15:08, 25 May 2023 (UTC)

There are lots of <someone>'s Number constants. We could have an entire phonebook of these. Barmar (talk) 17:53, 25 May 2023 (UTC)
I tried phoning Graham's Number, once. I'm still not yet finished dialling! 19:22, 25 May 2023 (UTC)
I thought you meant Alexander Graham Bell's number. 23:04, 25 May 2023 (UTC)
Shouldn't AG Bell's number be 1? Barmar (talk) 16:03, 27 May 2023 (UTC)
Or 2. (Thomas Watson being on 1.) 18:14, 27 May 2023 (UTC)
Chandresekhar's Limit = 3 pints? Barmar (talk) 17:53, 25 May 2023 (UTC)
Don't forget that numbers are now Euler letters! 20:41, 25 May 2023 (UTC)

From a friend, regarding Fermi's current temperature: The typical ground temperature of a burial plot in Chicago depends on the depth and the season. According to the Illinois State Climatologist Office, the average soil temperature at 4 inches depth ranges from about 25°F in January to about 75°F in July. The average soil temperature at 8 inches depth ranges from about 30°F in January to about 77°F in July. These measurements are made under grass, so the soil temperature under other ground covers or under bare ground may vary somewhat from those shown here. In the winter, when the ground is frozen, cemeteries are able to continue burying the dead by using special equipment such as frost rippers or steamers to break through the frozen layer of soil. They also use heaters or blankets to keep the graves open until the burial service is completed. RandalSchwartz (talk) 23:09, 25 May 2023 (UTC)

Assuming his grave is 6 feet deep and his body is at 5 feet deep, he's going to be below the frost line, which is 40" in Chicago, so the temperature is never going to drop below 32°F. Based on the charts at https://www.builditsolar.com/Projects/Cooling/EarthTemperatures.htm, he should see temperatures ranging from 40° to 62°. Interestingly enough, at that depth, the soil temperature will lag behind the surface temperature enough that the coldest temperatures will be in March and the warmest will be in September. 03:36, 26 May 2023 (UTC)

Pretty sure the Schwarzschild radius is the radius of a curled up child, not of Mr. Schwarzschild. 08:49, 26 May 2023 (UTC)

68cm diameter of a person curled up seems about right. 15:23, 26 May 2023 (UTC)

Besides Smoot, there's Erdős number.

The Erdős number (Hungarian: [ˈɛrdøːʃ]) describes the "collaborative distance" between mathematician Paul Erdős and another person, as measured by authorship of mathematical papers.
The Erdős number or Paul Erdős is 0. Anyone who collaborated with him has Erdős number 1, and anyone who collaborated with someone with Erdős number 1 (but not Paul Erdős himself) has Erdős number 2 - and so on. Taking this comic's interpretation, the Erdős number should be either 1, 'cause there was only one Paul Erdős, or 0, because he's dead. 15:23, 26 May 2023 (UTC)
What is the Erdős number of Kevin Bacon? 15:21, 30 May 2023 (UTC)
I believe infinite, as he has published no relevant papers. (talk) 16:17, 26 October 2023 (please sign your comments with ~~~~)
That'd be 'undefined', then. 23:52, 27 October 2023 (UTC)
There's also the Helen: a unit of beauty named after Helen of Troy [2]
I believe Système international d'unités wishes, in a reversal from the kilogram, treat the millihelen (mH) as the fundemental base unit. But they are having trouble finding a better definition prototype than the original platinum-iridium ship. 08:51, 31 May 2023 (UTC)

Actually, anyone using Celsius degrees on daily basis, would write 36.6 degrees as human body temperature. 37 is slightly elevated. So 37 looks like "American converted known value from Farenheit scale" -- (talk) 12:18, 29 May 2023 (please sign your comments with ~~~~)

Well, 33.2–38.2°C (or 91.8–100.8°F, if you prefer, give or take the rounding in both) can actually be normal, given acceptible changes in conditions (environmental) and condition (physiological). And of course it depends on which way you measure the core/surface temperature, even for the same person at the same instant. But it's the oft-quoted value. And just because it normally drifts doesn't mean that it hasn't abnormally drifted, so can still be taken as a cue to check why it's a degree or three off the 'standard'.
I suspect you could be more exacting with an uncomplaining long-dead corpse, but perhaps you don't need quite so much analysis when you already know that it's a long-dead corpse you're dealing with, once you've gotten past the need to assess the rate of insect pupation/etc. ;) 13:08, 29 May 2023 (UTC)