Wednesday, July 04, 2012

Paradigm unshift

Scientists recently observed traces of a suicidal Higgs boson. That is a good moment for celebrating science. Without fruits of science, you wouldn't read this message. You wouldn't have the equipment to receive it, and you would be busy doing heavy physical work for subsistence. The www protocol which tells your browser how to render this page was first designed in the very same CERN. Thanks to science, engineering and markets, machines do things for you, giving you ample food and leisure.

Therefore science is worth celebrating and worth funding, but also worth watching over to prevent nasty stuff, say, geneticists developing artificial pandemies.

Peer review is central to science. Symbolically, this big moment was chosen by peer review - peer physicists determined that the smoking ruins of some boson, probably Higgs boson were sighted, and that it was an important milestone.

The non-technical Wikipedia overview of Higgs boson is perfect. It tells for laymen why those whippersnappers matter. It also contains links to the real stuff for those who have IQ and training to understand particle physics (I don't.) And it captures the uncertainty under which scientists work.

In particle physics, elementary particles and forces give rise to the world around us. Physicists explain the behaviors of these particles and how they interact using the Standard Model—a widely accepted framework believed to explain most of the world we see around us. Initially, when these models were being developed and tested, it seemed that the mathematics behind those models which were satisfactory in areas already tested would also forbid elementary particles from having any mass, which showed clearly that these initial models were incomplete. In 1964 three groups of physicists almost simultaneously released papers describing how masses could be given to these particles, using approaches known as symmetry breaking. This approach allowed the particles to obtain a mass, without breaking other parts of particle physics theory that were already believed reasonably correct. This idea became known as the Higgs Mechanism (not the same as the boson), and later experiments confirmed that such a mechanism does happen—but they could not show exactly how it happens.

The leading and simplest theory for how this effect actually takes place in nature was that if a particular kind of "field" (known as a Higgs Field) happened to permeate space, and if it could interact with fundamental particles in a particular way, then this would give rise to a Higgs Mechanism in nature, and would therefore create around us the phenomenon we call "mass". Around the 1960s and 1970s the Standard Model of physics was developed on this basis, and it included a prediction and requirement that for these things to be true, there had to be an undiscovered boson—one of the fundamental particles—as the counterpart of this field. This would be the Higgs boson. If the Higgs boson was confirmed to exist, as the Standard Model suggested, then scientists could be satisfied that the Standard Model was fundamentally correct. If the Higgs boson was confirmed not to exist, then other theories would be considered as candidates instead.

The Standard Model also made clear that the Higgs boson would be very difficult to demonstrate. It only exists for a tiny fraction of a second before breaking up into other particles, so fast that it cannot be directly detected and can only be detected by identifying the results of its immediate decay and analyzing them to show they were probably created by a Higgs boson and not some other reason. The Higgs boson requires so much energy to create (compared to many other fundamental particles) that it also requires a massive particle accelerator to create collisions energetic enough to create it and record the traces of its decay. Given a suitable accelerator and appropriate detectors, scientists can record trillions of particles colliding, and analyze the data for collisions likely to be a Higgs boson, and then perform further analysis to test how likely it is that the results combined show a Higgs boson does exist, and the results are not just due to chance.

Experiments to try and show whether the Higgs boson did or did not exist began in the 1980s but until the 2000s it could only be said that certain areas were plausible, or ruled out. In 2008 the Large Hadron Collider ("LHC") was inaugurated, being the most powerful particle accelerator ever built. It was designed especially for this experiment, and other very high energy tests of the Standard Model. In 2010 it began its primary research role which was to prove whether or not the Higgs boson actually existed.

In late 2011 two of the LHC's experiments independently began to suggest "hints" of a Higgs boson detection around 125 GeV (the unit of particle mass). In July 2012 CERN announced[1] evidence of discovery of a boson with an energy level and other properties consistent with those expected in a Higgs boson. The available data raise a high statistical likelihood that the Higgs boson had been confirmed. As a result, further work will be necessary for the discovery of the Higgs boson to be considered conclusive (or disproved). If the newly discovered particle is indeed the Higgs boson, attention will turn to considering whether its characteristics match one of the extant versions of the Standard Model. The CERN data include clues that the additional bosons or similar-mass particles may have been discovered as well as, or instead of, the Higgs itself. If a different boson were confirmed, it would allow and require the development of new theories to supplant the current Standard Model.

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