A Few Fundamental Physics and Astronomy Questions for the Next Few Decades

There is no doubt that progress in physics and astronomy in the past century has been phenomenal. From the tiny matter particles (such as quarks, electrons, neutrinos) of the so-called "Standard Model" and the associated force-carrying bosons (such as photons, gluons, W, Z), to the cosmic microwave background and the vast, accelerating universe, physicists and astronomers have come together to explore an astonishing range of cosmic phenomena. When you think about the fact that the atomic nucleus was only discovered in 1911, and that only in 1924 astronomer Edwin Hubble confirmed that galaxies existed beyond our own Milky Way, you cannot avoid being amazed. The latest journeys into the largest and smallest scales have continued to produce spectacular results. On one hand is the discovery of the Higgs boson -- the particle that endows elementary particles with mass -- at the Large Hadron Collider (Figure 1). On the other, are the highly detailed observations of the cosmic microwave background--the afterglow of the Big Bang -- by the Planck satellite (Figure 2).

One may wonder which crucial questions will almost certainly occupy physicists and astronomers working together in the coming few decades. Here are a few of the remaining puzzles.