Comment by 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.
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.
OP: "It’s essentially asking why is the speed of light 299,798,452 m/s or the gravitational constant 6.67x10-11 Nm2/kg2 I’m sure a universe could work with those constants varied but that’s the one we have in our universe.
There could be hypothetical universes with protons being half of electron and atoms would have twice the protons.
However the fundamental constants are just that. A number that allows us to reason about how the universe works.
As to why the number is that, gotta ask your God why they chose that specific value."
And so the post I responded too said these constants are totally RANDOM / ARBITRARY.
But they cannot be otherwise the universe wouldn't work (as far as we know).
The measurements or units we use to express these are arbitrary-- but the constants themselves are DERIVED from the system we call the universe. Without them the system wouldn't work.
Is this really so controversial?
As I said, people were talking past each other. I don’t agree with the guys argument as to why that matters. I just don’t agree with your explanation.
My objection to your post is that the meter being defined based on physical reality isn’t meaningful. It isn’t the same thing as saying “the speed of light is c because c is the speed of light and we’ve derived it to be c (in our system of units).”
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The relation between the meter as defined and the speed of light isn’t arbitrary. But the value of c in terms of meters isn’t really privileged compared to the value of c in parsecs: both numerical values are only the number they are because you’ve picked an arbitrary unit to measure them by.
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