Quantum Gravity

What are the four fundamental forces of nature?
Answered by Discovery Channel
  • Discovery Channel

    Discovery Channel

  1. The four fundamental forces of nature are electromagnetism, the strong force, the weak force and gravity. If these forces weren't present in our universe, all the matter in the cosmos would drift apart and float away. Scientists believe these forces were present at the beginning of the universe in the form of a single unified force.

    The strong force is what holds the nucleus of an atom together. It's not terribly long-ranged and is primarily attractive; electromagnetism is weaker than the strong force and can be seen in the repulsion of like charges and in the reaction between magnets -- it can repulse or attract and only occurs between things that carry a charge of electricity; the weak force is just that -- a weakling, short in range, causing radioactive decay and neutrino interplay; gravity is weak (which sounds counterintuitive at first glance) but is also extremely long range and always attractive between any two things [source: University of Tennessee].

    As fascinating as these four fundamental forces are by themselves, were they once all one? Many scientists believe that at the beginning of the universe there was one unified force driving everything, and that the four fundamental forces we know today were parts of this one. Still unproved, theoretical physicists are trying to construct a grand, unified theory that will explain this, although there are many issues still to be clarified, such as the relationship between quantum mechanics and gravity. It has already been proven that the electromagnetic force and the weak nuclear force combine when brought to a temperature of 1015 K (1368 F), or 100 giga-electron volts (100 GeV) of energy. At even greater temperatures, it is predicted that the resulting electro-weak force would combine with the strong force, and at temperatures near to those at the start of the Big Bang (1019 GeV) all forces would be united.

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