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Sunday, July 8, 2012

Higgs boson in the history of science

Scientific knowledge has developed over centuries. The journey of discovery includes long periods of experiments and the collecting of careful measurements (empirical data). Every once in a great while important milestones occur when a pattern in this data is recognised.

Identifying chemical compounds, chemical elements and developing processes to separate mixtures of each progressed gradually over centuries. A major milestone was reached in 1869 when Dmitri Ivanovich Mendeleev proposed a Period of Table of Chemical Elements that fitted the known elements according to patterns of physical properties that many scientists and researchers had discovered and studied.

The Periodic Table of Chemical Elements originally contained gaps that suggested a number of chemical elements may exist and that remained to be discovered.
Periodic Table of Chemical Elements
Periodic Table of Chemical Elements
Another milestone occurred at the dawn of the twentieth century when Marie Curie revealed two revolutionary ideas for which she was awarded Nobel Prizes in Physics and in Chemistry.

"Marie drew the conclusion that the ability to radiate did not depend on the arrangement of the atoms in a molecule, it must be linked to the interior of the atom itself. This discovery was absolutely revolutionary."
"For the first time in history it could be shown that an element could be transmuted into another element, revolutionizing chemistry and signifying a new epoch."

Together with her husband, she was awarded half of the Nobel Prize for Physics in 1903 for their study into the spontaneous radiation discovered by Henri Becquerel in 1896, who was awarded the other half of the Prize. Marie Curie was awarded a second Nobel Prize, in Chemistry, in 1911.

This type of scientific milestone is different in character to the work of Mendeleev. It occurs when completely new and previously unknown features of the natural world are revealed. It built on Mendeleev's work - Marie Curie's insights were gained after she discovered two new chemical elements, polonium and radium and devised techniques to isolate radium in sufficient quantities to study its properties. Polonium is named after her homeland, Poland.

Radium's radioactivity was so great that it could not be ignored. It seemed to contradict the principle of the conservation of energy and therefore forced a reconsideration of the foundations of physics. On the experimental level the discovery of radium provided men like Ernest Rutherford with sources of radioactivity with which they could probe the structure of the atom.

Rutherford conducted experiments with alpha radiation and as a result in 1910  introduced a new model of an atom that contained a minute nucleus possessing almost all the atom's mass.

The first half of the twentieth century was a period of remarkable scientific advances including Niels Bohr's atomic model (1913), Erwin Schrödinger's development of quantum mechanics (1925) and Albert Einstein's theory of mass-energy equivalence (1905) among numerous others.

It was also remarkable for an "embarrassment of riches" of fundamental sub-atomic particles that were discovered. At first each discoverer of a new sub-atomic particle was almost guaranteed a Nobel Prize in Physics. Later, each new discovery was greeted with dismay at the growing complexity of what was originally thought to be a simple quest to identify and characterise a limited number of fundamental particles.

The identification of new sub-atomic particles continued and eventually in the mid 1960s a model to fit all this empirical evidence into a coherent framework was more-or-less settled. This model known as The Standard Model of Fundamental Particles and Interactions parallels the breakthrough that Mendeleev's Periodic Table of Chemical Elements achieved in 1869.
The Standard Model of Fundamental Particles and Interactions
The Standard Model of Fundamental Particles and Interactions

Like Mendeleev's model of one century earlier, The Standard Model of Fundamental Particles and Interactions also identified a number of missing pieces that, if the model was correct, should be able to be found.

Of the missing pieces, the Higgs boson was predicted and its existence was crucial in checking the validity of the Standard Model.

See more information on the hunt for the elusive Higgs Boson at How Stuff Works:

What exactly is the Higgs boson?