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Physics in the News
Title: From Protons To Planets: The Quest For A Theory Of Everything
Date: 06/29/2010
Publication: Berkeley Science Review
Extended Text:

From protons to planets
The quest for a theory of everything

by Phuongmai Truong

Textbooks 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.

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