Discovery Science: Physics and Technology – Physics – The great Unification

Physics and Technology – Physics – The great Unification

In the early 20th century, quantum mechanics and relativity theory exposed the limits of classical physics. More than this, they raised fundamental new questions.

First, the atom was replaced as the basic building block of nature by an increasingly diverse collection of elementary particles. Unfortunately, however, the two main pillars of the modern physical view of the world-quantum mechanics and relativity theory-showed themselves to be fundamentally incompatible.

Curved space-time cannot be integrated into quantum theory, therefore the greatest current challenge for modern physics is to achieve a unified description of all four fundamental natural forces or interactions. This attempt has become known as the search for a “theory of everything,” a term that was first used with an ironic undertone.

Encouraging observations

While the first half of the 20th century was a time of discovery and experimentation, the second half of the century brought the first steps toward the reconciliation of the many theories utilized by the field of physics. First, the theory of quarks brought order into the “particle zoo” when it was discovered that, except for electrons and neutrinos, nearly all known particles-even those within atomic nuclei-turned out to be combinations of two or three quarks.

Then, experiments showed that at rising energy levels, the differences between electromagnetism and the strong and weak nuclear forces begin to disappear. A temperature was even identified at which the three forces behave identically—although this temperature is so high that it cannot be reproduced in any laboratory. The third success came with the unification of quantum mechanics, special relativity, and electrodynamics, into quantum electrodynamics (QED).

Mathematically, this theory is closely related to the quantum theory of the strong interaction or color force, quantum chromodynamics (QCD). The pioneer mystery Even today, mysteries still appear in unexpected places. Space probes were launched in the direction of Jupiter and Saturn during the 1970s as part of the Pioneer and Voyager programs.

They have since left the solar system, but their positions are still being tracked. In recent years, however, it has become clear that their paths cannot be described accurately either by known classical celestial mechanics or by relativity theory.


Born in 1933, Steven Weinberg is one of the most prominent U.S. physicists of his generation His book The First Three Minutes, describing the time just after the big bang, was an international bestseller.

In his most important contribution to physics, he combined electro-magnetism and the weak nuclear force into the “electroweak force,” showing that both the forces arose from an original electroweak force existing shortly after the big bang