I've got loads of respect for leading-edge scientists. This is not so much because of any specific content they are dealing with, although I do have a great lay interest in several fields of science. I most respect their ability to devise tests for their hypotheses. It seems to me that the greatest knack the scientist must have is the ability to ask, 'How would I test that?' and then come up with an answer.
How do we leverage things we know to test for answers to things we don't know? How do we swing on the vine that dangles from a tree in the realm of the known so as to reach a new tree and thereby extend the realm itself?
Scientific pioneers have to do just that. I guess I'm most impressed by the ingenuity of those who operate at the largest and the smallest scales of physics. In cosmology and in particle and quantum physics, one has to be able to draw conclusions based on observation of things other than (but related to) the ones the hypothesis concerns. I'm sure this applies to many other realms as well, it just jumps out to me most in these fields.
How does one go about weighing a planet, a star, a galaxy? Or measuring the temperature of the sun or other distant stars? How does one determine the mass of the electron or the strength of the weak force? It's obviously possible, since it's been done.
Advances are usually made via a succession of small steps. The trees we've swung to have generally been close to those we swung from. I would love to know which were the biggest steps. Who REALLY made a leap beyond the (already very impressive) hops science generally advances by?
And will the empirical mind continue to push the limits of the scientifically knowable? Will the largely philosophical debates about interpretations of quantum mechanics or consciousness or free will be reeled in by the inexorable force of those who ask, 'How would I test that?'? At the greatest reaches, the biggest challenge to testing may be getting yourself out of the way of the test or, alternatively, designing yourself into in a way that lends itself to replication.
I think that some questions and the tests of them will remain subjective - only lending themselves to execution by one individual for herself. Their results are not necessarily reproducible because of the impossibility of replicating ‘similar conditions’. Here, I’m thinking of the careful inquiries each of us can do into our own experience of the world. ‘Does my story of the world and myself bear scrutiny? How would I test that?’