19* Numbers, That's All Anyone Needs

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Milky Way above NZ native plants and a wooden seat
There's your age, your house number, your IR number, your employee number, your bank number, your ... nah, none of these are important to the universe.

According to some VERY clever people, there are nineteen (give or take) numbers that help determine EVERYTHING.

These aren't numbers that are the result of a function, they aren't worked out through maths, they are what they are. They are static, one off, 'this is it' numbers.
A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that cannot be explained by a theory and therefore must be measured experimentally. It is distinct from a mathematical constant, which has a fixed numerical value, but does not directly involve any physical measurement.
Speed of light is probably the one you can name. It is a fixed number, doesn't change no matter where you are in this universe, it is fixed. It is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour).
There are many physical constants in science, some of the most widely recognized being the speed of light in vacuum c, the gravitational constant G, the Planck constant h, the electric constant ε0, and the elementary charge e.
So, there are nineteen, or so, of these types of numbers. They can be written down, and if they weren't their particular values this universe would be very different.

These nineteen(ish) numbers are also a mystery. No-one knows why they are the number they are. Why is the speed of light 299,792,458 metres per second, no-one knows. My default reason for everything though is entropy, it'll have something to do with entropy 😀

So, what are these numbers:
  1. elementary charge [e] 1.602176634×10−19C
  2. Newtonian constant of gravitation [G] 6.67430(15)×10−11m3⋅kg−1⋅s−2
  3. Planck constant [h] 6.62607015×10−34J⋅Hz−1
  4. speed of light in vacuum [c] 299792458 m⋅s−1
  5. vacuum electric permittivity [ε0] 8.8541878188(14)×10−12F⋅m−1
  6. vacuum magnetic permeability [μ0] 1.25663706127(20)×10−6N⋅A−2
  7. electron mass [me] 9.1093837139(28)×10−31kg
  8. fine-structure constant [α = e2/2ε0hc] 0.0072973525643(11)
  9. Josephson constant [KJ = 2e/h] 483597.8484...×109Hz⋅V−1
  10. Rydberg constant [R∞ = α2mec/2h] 10973731.568157(12)m−1
  11. von Klitzing constant [RK = h/e2] 25812.80745... Ω
Yeah, nineteen is a number bandied around however all the lists of fundamental constants are bigger. Maybe the "number of physical constants" is, itself, a physical constant and our table of physical contestants are yet to be detected properly 😁

So there you have it though, a list of fancy named numbers that determine how our universe operates and we have no idea why they are what they are, they just are.

BREAKING NEWS!
Using the new technology, scientists may be able to determine if fundamental constants, such as the fine-structure constant which sets the strength of the force that holds atoms together, vary. Hints from astronomy suggest that the fine-structure constant might not be the same everywhere in the universe or at all points in time. Precise measurement using the nuclear clock of the fine-structure constant could completely rewrite some of these most basic laws of nature.


Wikipedia sources:

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