Or, as an alternate to SS's elegant and more accurate solution is: 1mg of He4 corresponds to about 1.5E+20 molecules (=6/4*10^(23-3)), each of which weighs about 4GeV/c^2. So the answer is 6E+20GeV, which is also roughly 1mg in units where c=1.
Haha natural unit nonsense FTW. Or in other words: how to come up with circular self-referential answers.
Plus, very few units are really all that 'natural'. It's probably better to come up with a relatively arbitrary scale, which increases and decreases logically (as SI system) instead of having WTF moments later on when the 'natural' unit is found to not really exist, or even more confusingly, if it turns out to be a different value.
SI is more than fine IMO.
Although anything is better than pound-furlongs (instead of Newton-meters) system of units that one Physics professor used in his exams. I think it was just to get us annoyed enough never to use anything but the SI system ever again.
c=1 is common because it brings out the energy mass equivalence and simplifies things a lot; certainly no one uses the full MKS in particle physics. Imagine carrying around "c" in a one page equation....
Also, re the second answer, GeV is a perfectly good energy unit, given there is no context (10^21GeV vs 10^11J) - perhaps I originally wanted to compare He, say, to the max root-s for Au on Au at RHIC? Of course you're not gonna use He4 to make way for the swimming pool in the back yard, at 8MeV binding energy.
Edit: Of course 0.1TJ does sound better than 1,000,000 YeV!
Last edited by Quaggas; 25-07-2010 at 11:20 AM.
GeV is fine. Plus, you do need a few competing units, just to piss off high school students. And to crash NASA probes from time to time.
The Atlantic Wire - Genetic Scientist: 'We Have Learned Nothing From the Genome'
Awesomely bitchy interview.
Haha loving the swipes at Collins.
On the other hand, it's barely been ten years - obviously there hasn't been any medical benefits. Give it some time FFS.
Two words; cold fusion.
I don't think there are any parallels.
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