“Is N=2 large?” queried Kitano, Yamada and Yamazaki in their paper title. Exactly five months later, they co-wrote with Matsudo a paper titled “N=2 is large“, proving that their question was, after all, rhetorical.
Papers ask the darndest things. Collected below are titular posers from the field’s literature that keep us up at night.
Who?
Who is afraid of quadratic divergences?
Who is afraid of CPT violations?
How?
How bright is the proton?
How brightly does the glasma shine?
How bright can the brightest neutrino source be?
How stable is the photon?
(Abstract: “Yes, the photon.”)
How good is the Villain approximation?
How light is dark?
How many solar neutrino experiments are wrong?
How many thoughts are there?
How would a kilonova look on camera?
How does a collapsing star look?
How much information is in a jet?
How fast can a black hole eat?
How straight is the Linac and how much does it vibrate?
How do we build Bjorken’s 1000 TeV machine?
How black is a constituent quark?
How does a pseudoscalar glueball come unglued?
Bonus
How I spent my summer vacation
Why?
Why is 
Why do we flush gas in gaseous detectors?
Why continue with nuclear physics?
What and why are Siberian snakes?
Why does the proton beam have a hole?
Why are physicists going underground?
Why do nucleons behave like nucleons inside nuclei and not like peas in a meson soup?
Bonus
Why I would be very sad if a Higgs boson were discovered
Why the proton is getting bigger