Comment by lostemptations5

2 years ago

They are arbitrary in the sense that we could just change them and the universe wouldn't fl appart -- or are they derived from aonething deeper.

8 comments

lostemptations5

Reply
fiddlerwoaroof  2 years ago

The obvious way in which those constants are arbitrary is that the meter is just a random length we compare other lengths to (and the gram is an arbitrary mass we use). So, the precise numbers are only meaningful as part of a system built on these units

  • lostemptations5  2 years ago

    "Since 2019 the metre has been defined as the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second, where the second is defined by a hyperfine transition frequency of caesium."

    (https://en.m.wikipedia.org/wiki/Metre)

    I wouldn't call it totally random, no. It's really derived from somethings real in this universe.

    > So, the precise numbers are only meaningful as part of a system built on these units

    That doesn't sound particularly random. And in fact we agree here.

    • cgriswald  2 years ago

      No.

      Some of you are talking past each other. The speed of light being exactly the number c is arbitrary, because the choice to use the ephemeris second as the base unit of time (regardless of the precision we get by now using cesium atom “beats”) is arbitrary even though it’s based on something real. That’s just standardizing our arbitrary choice.

      The charge of an electron is also effectively arbitrary for the same reason. We can have our units based on whatever real thing we want.

      What isn’t arbitrary is that, whatever units we use and whatever number we arrive at for the charge of the electron, it true that the quark charge units are (1/3)e. Thus, as the poster pointed out there is a fundamental difference in asking why it works out that way compared to asking why the speed of light is a particular derived number.

      tldr: The poster above is wrong about his claim that it’s like asking “Why is the speed of light…” because he’s comparing a number to a relationship.

      5 replies →