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[TheBiggerFish]

Number of carbon 12 atoms in 12g. That'd be the same with any system of mass.

Or that.

[Bauglir]

WTF is up with Avogadro's Number? Why don't they just round it up to one octillion? Why did they choose this weird arbitrary number to count atoms and molecules in groups of?

Well, it started out as the number of atoms of Hydrogen in a gram of Hydrogen, which is reasonable enough. Then it got adjusted to the number of atoms of carbon-12 in 12 grams of carbon, which is slightly different due to the slight difference in mass of neutrons, and then apparently it was generalized somehow?

I guess it does ultimately come down to water, though, since the gram was original defined in terms of water.

[miauw62]

Yeah the number is defined in such a way that the relative atomic weight of an element = the weight in kg of a mole of that element. Which is pretty convenient.

[Frumple]

They really missed the mark with that one when they didn't base it off of avocados.

[Arx]

Scientific constants generally don't make much sense. It's just the way things are, and you can't really 'just round it off' or you'll have to either adjust everything else to no longer make sense historically or deal with screwing everything else up.

[Loud Whispers]

Scientific constants generally don't make much sense. It's just the way things are, and you can't really 'just round it off' or you'll have to either adjust everything else to no longer make sense historically or deal with screwing everything else up.

If energy cannot be created or destroyed how did anything in the Universe come to be
3deep5me

[Graknorke]

Jesus did it. Maybe if you didn't love sinning so much it would be self-evident.

[i2amroy]

If energy cannot be created or destroyed how did anything in the Universe come to be
3deep5me

#SeriousResponsesToJokes

That's one of those rules that seems totally true, but when you get to the higher levels they are like, "Well, technically it can't be created or destroyed, but since mass and energy are the same thing, you can take a huge amount of energy can convert it to a small amount of mass, or take a small amount of mass and convert it to a large amount of energy." Thus lots of energy in the big bang -> small amounts of mass in the universe.

[NJW2000]

Also, you could create energy and mass, if you could make quantum, but larger.

[Il Palazzo]

WTF is up with Avogadro's Number? Why don't they just round it up to one octillion? Why did they choose this weird arbitrary number to count atoms and molecules in groups of?

It's not arbitrary, and it can't be changed to some (actually arbitrary) number, because it's a conversion factor between two specific systems of measuring mass. Just as there are 0.45-something kg in a pound, there are N_A units of atomic mass in a gram.

[Rose]

I just wanna know how the hell they figured the number out.

[GiglameshDespair]

I just wanna know how the hell they figured the number out.

I believe it was first worked out by coulometry.

[ggamer]

I just wanna know how the hell they figured the number out.

wizards

[i2amroy]

I just wanna know how the hell they figured the number out.

I believe it was first worked out by coulometry.

It was actually first worked out by some estimates while looking at the kinetic motions of gas and brownian motion (by Josef Loschmidt and later Jean Baptiste Perrin). But yeah, since then we've used many different methods to estimate more precise values of the number, ranging from actually measuring the charge on an individual electron to "count" the electrons, to weighing an ultra pure sample of a material and then using the crystal structure density to estimate the number of individual atoms.

[Dutrius]

If energy cannot be created or destroyed how did anything in the Universe come to be
3deep5me

#SeriousResponsesToJokes

That's one of those rules that seems totally true, but when you get to the higher levels they are like, "Well, technically it can't be created or destroyed, but since mass and energy are the same thing, you can take a huge amount of energy can convert it to a small amount of mass, or take a small amount of mass and convert it to a large amount of energy." Thus lots of energy in the big bang -> small amounts of mass in the universe.

Doesn't explain the apparent lack of antimatter though.