I Jansky: When Physics Majors Should Expect It

[strangerep]

At what point during study for a reputable physics degree should one normally encounter the "Jansky"?

I.e., at what point is it reasonable for a lecturer (or textbook writer!) to assume the existence and meaning of "Jansky" as basic prior knowledge?

 

[Orodruin]

For a general physics degree, I would say it is not reasonable to assume any knowledge. It is a unit mostly seeing use in a particular subfield and unless students are specialising in that particular subfield they will most likely not be exposed or have very limited exposure.

 

[Baluncore]

At what point during study for a reputable physics degree should one normally encounter the "Jansky"?

One should only encounter SI units as part of a degree. Avoid the non-SI Jansky. The Jansky should be ignored until one makes experimental observations in radio astronomy.

 

[Ibix]

I made it through an entire physics degree without coming across it as far as I recall. So I'd say you introduce it in the first specialist astronomy course.

 

[strangerep]

Thank you all.

In case anyone is wondering, I came across this unit the hard way...

I've decided to try and improve my knowledge of the non-GR aspects of cosmology. So I've started working through Dodelson & Schmidt "Modern Cosmology" 2nd Ed (2021), intending to do every exercise properly. In ch1 (sigh), Ex 1.4, they ask the reader to convert from the CMB black body $I_\nu$ intensity-vs-frequency formula to the units on their graph Fig 1.7. Their vertical axis is labelled MJy/sr, which I thought meant Megajoule-year/sr (and now I don't know whether to sigh or laugh). Being determined to complete this should-be-simple exercise without looking at the solution, I wasted several hours. They only explain in their solution at the end of the book that the vertical axis is in these weird units called "Janskys".

Oh well, I guess I'll just have to re-acclimatize myself to the sloppy way these things are "taught" in physics courses, as opposed to (say) applied maths.

BTW, does anyone have suggestions for alternate very modern cosmology textbooks that force you to work through all the seriously tedious detail?

 

[vanhees71]

As usual, Weinberg is a very good but tedious choice. It's not that "modern" anymore given the quick development of cosmology, but it's reasonably new, I'd say:

S. Weinberg, Cosmology, Oxford University Press (2008)