Editing 2780: Physical Quantities

{{comic
| number    = 2780
| date      = May 24, 2023
| title     = Physical Quantities
| image     = physical_quantities_2x.png
| imagesize = 338x183px
| noexpand  = true
| titletext = The Hubble length is about 1.9 meters lying down; Edwin Hubble was a tall guy.
}}

==Explanation==

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 {{w|List of scientific units named after people|units named for people}}, only one is actually a measurement of its namesake: the {{w|Smoot}}.

;Hubble volume
In cosmology, a {{w|Hubble volume}} (named for the astronomer {{w|Edwin Hubble}}) is a spherical region of the observable universe.
The Hubble volume is approximately equal to 10<sup>31</sup> cubic light years (or about 10<sup>79</sup> 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[https://bionumbers.hms.harvard.edu/bionumber.aspx?s=n&v=3&id=109718], but Edwin Hubble was a big guy (see title text) and likely had an above-average volume.

;Schwarzschild radius
The {{w|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,{{fact}} while making them more spherical and easier to measure, so {{w|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
{{w|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 {{w|Paul Broca}}, which probably refers to the {{w|Body surface area|surface area of his body}} - about 1.7-1.8 m<sup>2</sup> 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 {{w|Fermi energy#Related quantities|related to the Fermi Energy}}, a quantum value inherent to very cold substances. The {{w|Human body temperature|temperature of an average human}} is about 37 degrees Celsius, so it makes sense that {{w|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
{{w|Planck units}} are naturally-derived measurements invented by {{w|Max Planck}}; the Planck length (approximately 1.6×10<sup>-35</sup> 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). His "length" is given as 1.76m, or roughly 5'9". 

;Hubble length (title text)
A {{w|Hubble's_law#Hubble_length|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.

==Transcript==
:[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: 1.7m<sup>2</sup>
:Fermi temperature: 37°C
:Planck length: 1.76m (lying down)


{{comic discussion}}

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