Editing 3086: Globe Safety

{{comic
| number    = 3086
| date      = May 7, 2025
| title     = Globe Safety
| image     = globe_safety_2x.png
| imagesize = 255x448px
| noexpand  = true
| titletext = Frankly, given their extreme gravitational fields and general instability, even 12-inch globes should probably be banned.
}}

==Explanation==
{{incomplete|This page was created by an EARTH MASS BOT THE SIZE OF A REGULAR BOT. Don't remove this notice too soon.}}
For any given amount of (stationary) mass, a value can be calculated known as the {{w|Schwarzschild radius}}, which denotes the radius of a spherical volume of space. If the mass somehow is compressed into this volume, it becomes so dense that it forms a {{w|black hole}}.

The newly-born black hole occupies that volume of space; more formally, that Schwarzschild radius then becomes the radius of that black hole's {{w|event horizon}}, the "surface" of the black hole to outside observers. When measured by a distant observer, the black hole's radius is the Schwarzschild radius. The event horizon is the "surface of no return": anything that falls into the black hole past its event horizon can't escape, and merges into it.

As for what's beyond the horizon? General relativity predicts an infinitely-dense {{w|singularity}} at the center, that anything falling past the event horizon eventually collides into. This is presumed a sign that the theory is failing at the extreme densities involved, where quantum mechanics can no longer be ignored, and some theory of {{w|quantum gravity}} is needed for a correct description; there are numerous speculative quantum qravity theories, but they remain untested at present, so the answer to what's "really" there is "we don't know (free Nobel up for grabs!)". (Relativity is a {{w|classical mechanics|"classical" theory}} which doesn't incorporate quantum mechanics at all, which is irrelevant on the scale of entire planets and stars and galaxies.)

Any arbitrary amount of mass has its corresponding value for its Schwarzschild radius. The Schwarzschild radius corresponding to the mass of the Earth is about 0.35 inches (roughly 9 mm, or a diameter of 7/10" or 18 mm), meaning if you could compress the Earth into a ball that small, it would be a black hole. The object at bottom right in the comic, with a triangular warning sign next to it, is a {{w|Black hole#Observation|depiction of a black hole}}.

{{w|Globes}}, in this context, are miniature re-creations of planet Earth, used to show its features without any of the [[977: Map Projections|typical problems of a flat map]]. [[Randall]] claims that safety standards are in place to ensure that globes are not manufactured at, below, or even close to the Schwarzschild radius of the Earth. The suggestion is that any globe of the Earth shares the same mass as the Earth and hence the same Schwarzschild radius. Such a globe might be made by creating a literal 1:1 replica of Earth and then shrinking it without distortion until it has the required size. This would, of course, give the most perfect maps; however, for each globe like this put on Earth, the Earth's mass would increase by its original amount, and in addition it would be impractical to make globes this way: such small amounts of matter of this density would [https://www.astronomy.com/science/what-if-a-tablespoonful-of-a-neutron-star-was-brought-to-earth/ immediately explode], vaporizing most or all of the Earth.

The title text suggests that globes up to 12 inches (30.5 cm) should be banned, due to their extreme density and gravitational field. The surface gravity of an object varies inversely with the square of its radius. Since the globe would have the same mass as the Earth, such a globe would exert massive, catastrophic gravitational forces at its surface. For a 12-inch globe, this would be 1.75 quadrillion times normal Earth gravity. The changes at the Earth's surface caused by these forces would immediately reduce the accuracy of the globe's representation of the area in which it is located. The gravitational effects on objects at a distance would be the same, but adding an Earth mass for each globe would still affect the orbits of satellites, other planets, etc. However, extreme gravity would exist for Earth-mass globes of any size, so the 12-inch cut-off is no less arbitrary than the 4-inch one.

==Transcript==
:[A standard globe of the Earth is shown. It stands on a typical stand which holds it by two arms at the poles, so it can turn around like the Earth does. The Earth is turned so it shows Australia at the bottom and most of Asia, including the entire India to the left. Only the very tip of Alaska can be seen of the Americas. Above the globe there is a double ended arrow that goes to two small lines that align with the edges of the globe (indicating the diameter). The arrow has been split in the middle and two lines of text are written in the gap. Above this text there is another line of text.]
:Remember:
:4 inches minimum

:[Beneath the globe there are two small drawings. The left shows the Earth and to the left of the Earth there is a double ended arrow ending at two lines that indicated the diameter of the Earth going from top to bottom. The distance of this is written in inches to the left. From the Earth an arrow points to another drawing, this time the typical depiction of a black hole, with a "hat" like shape. A triangular warning sign is shown a the top right of the black hole with an exclamation mark inside.]
:7/10"

:[Caption below the panel:]
:The Earth's Schwarzschild radius is about 0.35 inches, which is why safety regulations require desktop globes to be at least 4 inches in diameter.

{{comic discussion}}<noinclude>

[[Category:Astronomy]]
[[Category:Maps]]