MURRAY GELL-MANN (b.1929)

1964 – USA

‘Neutrons and protons are made up of particles called quarks. Like electrons, they cannot be subdivided further’

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MURRAY GELL-MANN

The standard model of particle physics divides all elementary particles into three groups:

six types of leptons
electron, electron neutrino, muon, muon neutrino, tau and tau neutrino
six types of quarks
up, down, charm, strange, top and bottom    and
four types of bosons

   
Ordinary matter is made up of:

protons
each an up-up-down quark triplet
neutrons
each an up-down-down quark triplet    and
electrons

 

Gell-Mann predicted the existence of three quarks; up, down and strange. Other scientists predicted another three. Quarks cannot exist singly.

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ABDUS SALAM (1926- 96)

1979 – Switzerland

‘Unification of the weak nuclear force and the electromagnetic force’

Photograph of Abdus Salam &copy:

ABDUS SALAM

Awarded the 1979 Nobel Prize for Physics along with Steven Weinberg and Sheldon Lee Glashow.

The Standard Model of quarks, electrons, neutrinos, gluons and Higgs particles.

Physicists introduced two new interactions, the strong and weak nuclear forces.
Unlike gravitation and electromagnetism these forces operate only at very short distances, distances of the order of the diameter of the nucleus or less.

Weak interactions change neutrons into protons and visa-versa in radioactive processes within stars. They are responsible for the so-called radioactive beta decay.

Strong forces hold quarks together inside protons and neutrons, as well as holding protons and neutrons together inside atomic nuclei.

The standard model of particle physics has unified electromagnetism with the weak interactions, and provides an explanation of the strong interactions. There are still huge gaps in the theories, for example there is no way of creating a unified understanding of strong and weak interactions.

Abdus Salam introduced the electroweak theory, which now sits at the core of the standard model of high-energy physics.
Energy in sunlight is produced when hydrogen fuses, or burns, into helium in a chain of nuclear reactions occurring in the Sun’s interior. In the first step of this chain reaction, weak forces enable hydrogen to transform into heavy hydrogen (deuterium).

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