4 ms·
Too many digits… TL;DR: .5 MeV and .9 GeV, respectively.
by Koshkin 5y ago
Too many digits… TL;DR: .5 MeV and .9 GeV, respectively.
- pdonis 5y agoThat's what the GP wrote. Their electron value has a decimal point before the last three digits. The GP values are approximately 510 keV and 938 MeV.
- gus_massa 5y agoI prefer to use the same unit for all numbers because it makes the comparison easier. The bound of mass of the neutrino is really low. Using M and G hides it. I was going to write: > For comparison, the mass of an electron is approximately 500,000 eV and the mass of a proton is 900,000,000 eV. But all the numbers I wrote are measured experimentally. Both values have a lot of experimentally measured digits! I only removed the part that overlaps with the uncertainty, because the notation with parenthesis is somewhat confusing.
- fknorangesite 5y ago> I prefer to use the same unit for all numbers because it makes the comparison easier. Thank you; this is a style guideline I wish more writers would adopt.
- robotresearcher 5y agoAlternatively, you can use exponential notation to compare numbers of very different sizes while writing them similarly and using the same unit.
- fknorangesite 5y agoYeah. The point is keeping the units consistent.
- deleted 5y ago[deleted]
- _Microft 5y ago511 keV and 938 MeV would have been much clearer than a distinction via comma/point like in 510,998 -> . <- 950 eV and 938,272 -> , <- 088 eV.
- gus_massa 5y agoI agree that the coma/point distinction is confusing. Also, I'd like to cut all the numbers in the same digit, but the next digit of the proton is too dubious. What about this version: > [an upper bound of 0.9 eV] For comparison, the mass of an electron is approximately 510998.9 eV and the mass of a proton is 938272088.0 eV.
- cecilpl2 5y agoI would just round to the nearest eV and keep the commas. > the mass of an electron is approximately 510,999 eV and the mass of a proton is 938,272,088 eV. This reads best to me.
- panda-giddiness 5y agoI know we're just bikeshedding now, but neutrino: 0. 8 eV/c^2 electron: 510 000. 0 eV/c^2 proton: 940 000 000. 0 eV/c^2 (Note: neutrino mass is given as the upper limit.)
- _Microft 5y agoThe first value has one, the others two significant figures in this example. The decimal point is also giving a false sense of certainty when used like this. You can find more about significant figures at Wikipedia: https://en.m.wikipedia.org/wiki/Significant_figures https://en.m.wikipedia.org/wiki/Significant_figures
- panda-giddiness 5y agoYes, I know about significant figures. In fact, I considered adding a note about sig figs before deciding it was too minor of a nitpick to elaborate on. Elsewhere in this thread, people have already listed these masses to much greater precision than almost anyone needs (including me, a practicing physicist); obviously people can infer I'm rounding from context. Of course, if you were to present the masses this way without context, you should add a note about rounding.
- codeflo 5y agoIn contrast to some sibling comments, I think using the same unit is a great idea. It’s just that long numbers with commas are a bit hard to read. At least I think 511 keV and 938 000 keV would have been another clear way to present those numbers.
- throwhauser 5y agoWriting out the digits gives a more visceral impression of the difference in weight, from roughly one, to a six-digit number, to a nine-digit number.