In physics we do things and afterwards worry about whether they worked
In 1900, David Hilbert published his list of 24 problems that he believed would be part of the development of mathematics in 20th century – and so they were! The closest we come to a 21st century analogue of these are the Clay Institute Millenium Prizes, and Steve Smale’s problems (though these have not, sadly, become as widely known as the others). Certainly anyone involved in mathematics research is aware of most, if not all of these problems.
Until today, the only physics counterpart to these that I was aware of was Wikipedia’s List of unsolved problems in physics – which is reasonably comprehensive and has drawn my attention to some interesting unexplained phenomena in CMP (ever heard of sonoluminescence?). However, just now I’ve come across a list by a Russian physicist Vitaly L. Ginzburg. It’s a list of thirty problems that Ginzburg thinks every physicist should know about.
As far as I know, the list first appeared in his 2003 Nobel Lecture. The paper may be found here, but I’ll reproduce the list below anyway:
Ginzburg also says that:
It should be added that three “great problems” of modern physics are also to be included in the “physics minimum,” included in the sense that they should be singled out in some way and specially discussed, and their development should be reviewed. This is discussed at some length in the book About Science, Myself, and Others (Ginzburg, 2003). The “great problems” are, ﬁrst, the increase in entropy, time irreversibility, and the “time arrow.” Second is the problem of interpretation of nonrelativistic quantum mechanics and the possibility of learning something new even in the ﬁeld of its applicability. I personally doubt this possibility but believe that one’s eyes should remain open. And third is the question of the emergence of life, i.e., the feasibility of explaining the origin of life and thought on the basis of physics alone. On the face of it, how could it be otherwise? But until the questions are elucidated, one cannot be quite sure of anything. I think that the problem of the origin of life will unreservedly be solved only after “life in a test-tube” is created. Until then, this will be an open question.
Ginzburg sadly passed away on November 8th, 2009. Among his achievements are a partially phenomenological theory of superconductivity, the Ginzburg-Landau theory, developed with Landau in 1950; the theory of electromagnetic wave propagation in plasmas (for example, in the ionosphere); and a theory of the origin of cosmic radiation. He was beyond a doubt a great physicst, and maybe one day his list will be counted among his greatest achievements. It might steer the progress of physics in the coming years -we’ll see.
Finally this last quote from Ginzburg’s paper:
One more concluding remark. In the past century, and even nowadays, one could encounter the opinion that in physics nearly everything had been done. There allegedly are only dim “cloudlets” in the sky or theory, which will soon be eliminated to give rise to the “theory of everything.” I consider these views as some kind of blindness. The entire history of physics, as well as the state of present-day physics and, in particular, astrophysics, testiﬁes to the opposite. In my view we are facing a boundless sea of unresolved problems.
It only remains for me to envy the younger members of the audience, who will witness a great many new, important, and interesting things.