Theory of Everything – Supersymmetry
Encouraged by the successful “electroweak” unification, researchers next attempted to add the strong interaction or color force. This has proved much more difficult.
The most promising attempt to find a theory of everything has been the concept of supersymmetry and superpartners. Symmetries-such as those of before and after, right and left, electricity and magnetism, QED and QCD-have always fascinated physicists. The current standard model of the elementary particles has a one-sided and asymmetrical aspect.
The quantum mechanical spin of electrons, neutrinos, and quarks has a value of a half, while that of energy particles, such as photons and gluons, is one. As early as 1973, the hypothesis was formulated that these elementary particles have “superpartners” with different spin values.
What advantages would be gained from this expansion in particles? The first is mathematical: the superpartners would prevent the appearance of undesirable infinite values in various equations, which then require “fine-tuning.”
In addition, the interactions between superpartners are closely related to the characteristics of space and time-a promising point of connection with general relativity theory. Ultimately, it was demonstrated in 1975 that, except for supersymmetry, there can be no other undiscovered symmetry in the universe.
Bringing dark matter to light
Supersymmetry could also solve the mystery of dark matter. It seems evident that superpartners could only transform into other superpartners; otherwise, scientists would have detected the products of their decay long ago.
Thus, there must be at least one smallest supersymmetrical particle that is nearly or completely stable. This would be an ideal candidate for dark matter: a non-observable particle with a large mass, present throughout the universe.
Stephen Hawking discovered an interesting link between quantum and gravitational theory. He studied the way virtual particles arising from fluctuations in the quantum vacuum behave in the vicinity of black holes.
The gravitation of black holes is so strong that particle-antiparticle pairs are ripped apart. While one is swallowed up by the black hole, the other may escape and become an elementary particle. Thus, black holes emit a weak particle stream known as “Hawking radiation.”
HAWKING RADIATION
British theoretical physicist Stephen Hawking (b 1942) is, like Isaac New ton before him. the Lucasian Professor of Mathematics at Cambridge University. In 1974, he provided the theoretical argument for the existence of Hawking radiation
There is much debate over this exotic radiation and many experiments are under way to vindicate or disprove this theory.
STRING THEORY
String theory interprets elementary particles as states of vibration in unimaginably small strings. This concept is automatically super-symmetrical and can also be applied to space and time (and thus to gravity).
How-ever, string theory only works in a system of at least ten spatial dimensions leading to new conclusions about the nature of gravity.
ISSUES TO SOLVE
FINE-TUNING presents a problem in physics. Whenever theoretical models do not match up with the results, fine-tuning of the equations is required in order to match the observations.
However, this does not mean that the equation was wrong, but rather that there is an unexplained effect upon the results. One possible explanation is the anthropic principle, stating that the results are being changed merely from being observed