Misplaced Pages

Revision as of 07:52, 31 March 2015

Archives

1, 2, 3, 4, 5

Speed of light

Hi, Quondum!I have noticed your recent edits to speed of light. I want to ask in this context about the possibility of expressing the speed of an object relatively to speed of light by comparison to the way it is done with the speed of sounds in relative Mach units.--94.53.199.249 (talk) 08:24, 13 January 2015 (UTC)

It is quite normal for physicists to use the speed of light as a unit in many contexts, for example by refering to a particle travelling at 0.999999 c. The further simplification may be made where this unit is omitted, or equivalently treated as equal to 1. You may be interested in reading articles such as Fundamental unit, Natural units and Geometrized units. This would seem to me to be comparable to how the Mach unit is used. —Quondum 15:24, 13 January 2015 (UTC)

Often "β" is used for the ratio of the speed of an object divided by the speed of light, ${\displaystyle \beta ={\frac {v}{c}}\,.}$ JRSpriggs (talk) 06:19, 14 January 2015 (UTC)

Is there a name for this beta in analogy to Mach number, like perhaps Einstein number of Photo-Mach?--94.53.199.249 (talk) 16:19, 17 February 2015 (UTC)

According to Lorentz transformation, β is called the velocity coefficient, and the vector equivalent is called the relative velocity vector, but don't take that as given. Simply "c" seems to be common as a "unit", as in my example above. Perhaps one could regard the symbol as 'c', and the name of the of the unit as 'celeritas'? There is a quantity closely related to β, called rapidity φ = artanh(β). —Quondum 19:49, 17 February 2015 (UTC)

Can this velocity coefficient β as a quantity be applied to the speed of sound? It seems that Mach unit is/can be a dimensionless unit for the speed of sound velocity coefficient.--94.53.199.249 (talk) 14:15, 14 March 2015 (UTC)

This seems to be going in circles. The Mach number is essentially that, except being defined in relation to the speed of sound in a medium. If you mean β in relation to the speed of light, yes, technically it can, though something at the speed of sound would then have β ≈ 10. —Quondum 15:11, 14 March 2015 (UTC)

Breit Rabi 1934

Ive transcribed the interesting commentary by Breit and Rabi from 1934 on the state of measurement of the neutron's magnetic moment and on the proton/electron composition of the neutron here. A copy paste from the reference PDF file. The reference is: Breit, G.; Rabi, I.I. (1934). "On the interpretation of present values of nuclear moments". Physical Review 46, p. 230. Thought you'd be interested. Bdushaw (talk) 22:51, 30 January 2015 (UTC)

Thanks. One gets a sense that there were a whole bunch of incompatible results that they had to extract sense from. I note an interesting comment: "The attempt at a conclusion that the neutron is not an elementary particle from the sign of its g factor appears to be premature. It is well known that interaction terms of Pauli's type can describe a particle with an arbitrary magnetic moment so that either sign of the g factor is in agreement with the view that the neutron is an elementary particle." I wonder what this meant. OTOH, the neutrino is considered to be an elementary particle, yet due to its nonzero rest mass apparently may have a tiny magnetic moment. Confusing. —Quondum 02:01, 31 January 2015 (UTC)

Gamma matrices

You should probably take the chance now to save your face. Think it over before you consider reverting. The statement, aside from being trivial, is now the best referenced statement in the article. Classification of Clifford algebras has nothing to do with this. YohanN7 (talk) 19:14, 8 March 2015 (UTC)

Thanks

Thanks for your perceptive guidance at Talk:International System of Units#The SI and the ISQ. NebY (talk) 16:32, 30 March 2015 (UTC)

My pleasure, though I just thought of it as chipping in my opinion (which is not always received well). I've actually learned a bit about the ISQ in the process. Thank you for polishing up that niggling issue of cross-dependence. —Quondum 16:52, 30 March 2015 (UTC)

Formal mediation has been requested

The Mediation Committee has received a request for formal mediation of the dispute relating to "Vectors are not tensors". As an editor concerned in this dispute, you are invited to participate in the mediation. Mediation is a voluntary process which resolves a dispute over article content by facilitation, consensus-building, and compromise among the involved editors. After reviewing the request page, the formal mediation policy, and the guide to formal mediation, please indicate in the "party agreement" section whether you agree to participate. Because requests must be responded to by the Mediation Committee within seven days, please respond to the request by 6 April 2015.

Discussion relating to the mediation request is welcome at the case talk page. Thank you.
Message delivered by MediationBot (talk) on behalf of the Mediation Committee. 21:47, 30 March 2015 (UTC)

Troublesome editor

I ran out of patience...

There is currently a discussion at Misplaced Pages:Administrators' noticeboard/Incidents regarding an issue with which you may have been involved. Thank you.

Bdushaw (talk) 06:56, 31 March 2015 (UTC)

You should not run out of patience, Bdushaw. These emotional reactions are not advisable (I'm also tempted to be irritated by Bdushaw's irritation/lack of cooperation, but that would be contrary to my own demand of advisability). Please familiarize yourself with relevant wikipolicies before making edits that on the verge of tendentiousness. The troublesome is certainly not me.--5.15.185.197 (talk) 07:51, 31 March 2015 (UTC)