Universe is about the size of a dust grain; the fundamental forces initially exist as one "superforce," but gravity quickly separates out.
1031 Kelvin*
10-35
Universe rapidly expands, doubling in size every 10-35 seconds; strong force separates out from the still-unified electromagnetic and weak forces; quarks, the building blocks of matter, now appear.
1027 K
10-11
Electromagnetic and weak forces are now separate; laws of nature observed today have emerged.
1015 K
10-6
Universe is a "soup" of elementary particles and quarks, which begin to bind together to form protons and neutrons.
1012 K
3 min.
Protons and neutrons combine to form simple atomic nuclei of hydrogen, helium and lithium; it is still too hot for atoms to form.
109 K
103 years
Electrons settle into orbit around atomic nuclei, forming the first hydrogen and then helium atoms.
105 K
[Zone of uncertainty]
109
Formation of earliest stars and galaxies; our own sun and solar system emerge several billion years later.
10K
3K
NOW
*273.16 K = 0o C = 32o F
The Fundamental Forces
Gravity
Electromagnetic Force
Strong Force
Weak Force
Gravity is the weakest of the four forces. It is so weak that if it were not for the fact that it can act over long distances and is always an attractive force, we'd never notice it. Every particle in the universe feels the force of gravity.
The second strongest of the four forces, it is the union of electricity and magnetism. This force interacts only with charged particles like electrons and quarks, and is much stronger than gravity.
The strongest of the four forces, with the shortest range of all. It holds the quarks together in the protons and neutrons, and holds protons and neutrons together to form the nuclei of atoms.
The second weakest of the four forces, it has a very short range. The weak force affects all matter particles, but not force-carrying particles. It is responsible for radioactive decay in nature.
