[ehswuttt] 42 in what units?

the Hitchhiker's Guide aliens ("mice") who received 42 as the answer to the Ultimate Question were probably surprised (among other reasons) that the Ultimate Answer was dimensionless.

one could easily imagine how the Ultimate Answer might be numbers: the free parameters of the Theory Of Everything -- numbers chosen by God -- but such parameters will likely have units.  it's conceivable that the Theory Of Everything has only one free parameter.  maybe the mice had already discovered such a Theory Of Everything, so Deep Thought did not include the rest of the theory as part of the Answer.  if so, the aliens probably wouldn't be surprised by a computer emitting the value of its free parameter.

the Answer being a dimensionless number constrains the Question a lot, though any question about a dimensioned number could be turned dimensionless by specifying units as part of the question.  but assuming the units weren't specified in advance, the units have to be somehow special if there really is a singular Ultimate Question: maybe Planck units, or its Theory-Of-Everything analogue.

the Answer being an integer also constrains the Question a lot.  maybe not so surprising because quantum mechanics often induces quantized constraints.  which overtone is our universe?

string theory: how many dimensions of space does our universe actually have?

currently, the Standard Model has a bunch of free parameters.  add to it massive neutrinos and general relativity (gravitational constant, cosmological constant, others?  maybe the number of dimensions of space and time), and you get a few more, about 25 numbers total that explain (some of) the universe.  they all have units, though some can be combined to obtain dimensionless constants, e.g., fine structure constant, whose reciprocal is coincidentally almost exactly the integer 137.

what would life be like in a hypothetical universe in which the value is exactly 137?  physics would (probably) be similar, but there would be tremendous curiosity to discover why the value is an integer.