Scientific Specific Units

[luisphysics]

(12-05-2015 07:01 PM)Tim Wessman Wrote:  It is true there is no way to define custom units. One problem we have is that the "unit" object is basically full in terms on the low level implementation at this point. We have discussed custom units (and "true" custom units not just the "make a synonym for another set of built in units - e.g. you could define _$, _€ that have no relation to any other group of base units) but that is definitely below the list of "fixing" the unit conversion UI. After that, some creative thinking to avoid backwards compatibility issues will be needed.


However, I'm perfectly happy to receive feedback/suggestions for new "built in" units that are well established in useage with actual names and (most importantly) are based on the existing base unit groups.

Well Honestly looking at most of my books the Prime team has a lot of good useful units like a barn which I use for nuclear cross sections, which is great.

But E=mc^2 => The units to Einstein's Energy to mass equation is MeV = kg * (m/s)^2

But no one ever divides out the c^2 numerically. The reason is that in most cases it just cancels out.

So the mass of the Proton is 1.67*10^-27kg eWWW no one wants to see that.
So what we do is just say the proton has 938 MeV/c^2. which is the same units as kilograms.

What we don't do is
((938E6_(eV))/(3E8_(m/s))^2 =1.04E-14 MeV/(m/s)^2
mainly because the answer is ugly.

And simplifying all the way is also ugly.
((938E6_(eV))/((3E8_(m/s))^2 )*(1.6E-19_(J)/_(eV)) = 1.67E-27 kg if you simplify J/(m/s)^2

I'd like to note that a good example and a familiar one, is the Higgs boson. Check out wiki https://en.wikipedia.org/wiki/Higgs_boson on the right side of the page for the mass. It is in GeV/c^2 because no one wants to write kg.

If you need a more convincing argument I can find one.