From protons to planets
The quest for a theory of everything
by Phuongmai Truong
show thousands of formulas and theories for the various branches of
physics—classical and quantum mechanics, astrophysics, particle physics,
condensed matter, optics, and relativity, to name just a few. But can
there be one ultimate theory from which every formula can be derived? In
the quest for such a "Theory of Everything" (TOE), Petr Hořava in the
UC Berkeley physics department has recently launched a new approach to
characterize an elusive concept known as quantum gravity.
The continuing search for a Theory of Everything
In 1687, Isaac Newton described the force of gravity, the phenomenon
that attracts objects with mass toward each other, holding together
clusters of galaxies and humans to the earth. Two hundred years later,
in 1864, James Clerk Maxwell united the electric force with the magnetic
force, creating the theory of electromagnetism. In the early 20th
century, Albert Einstein developed special and general relativity (see
sidebar) to complete thedescription of moving objects at the macroscopic
level, while Max Planck, Paul Dirac, Erwin Schrödinger, Werner
Heisenberg, and many other physicists successfully described the
subatomic world of photons and electrons with the theory of quantum
mechanics. The question of how protons and neutrons (the building blocks
of atoms) bind together to form atomic nuclei despite the repulsive
electric force between them was answered in 1970 with the discovery of
the strong and weak nuclear forces.
Up to this point, everything in our daily life can be explained by
one of these four main forces or a combination of them: gravitational
force, which keeps us on our chairs writing and reading this article;
electromagnetic force, which forms atoms and holds together molecules;
strong nuclear force, the glue keeping nuclei intact and weak nuclear
force, the cause of radioactivity and the burning of the sun.
Entire article: http://sciencereview.berkeley.edu/articleex.php?issue=18&article=features_04_quantum.