Supersymmetry
Apart from the unknowns, the inconsistencies and incongruities we presently know about could by themselves mean that another particle is being produced in the detectors alongside the Higgs like boson, which may mean that the new particle is something much more exotic, thereby providing a more complete model of the universe that includes the mysterious entities of dark matter and gravity. Perhaps these new particles are the superpartners of existing particles (sparticles) predicted by the string theory concept of supersymmetry (SUSY for short).[1] These superpartners would partner each standard model particle, with the fluctuations of the partners neatly each cancelling out the other[2].
The basic idea of supersymmetry was developed in the 1970s by physicists who were interested in the relationship between symmetries and particle physics[3]. It represents not just one theory but rather a framework for theories. The concept postulates that for every known particle species there should be a heavier and as yet undetected partner species, but having the same electrical and nuclear force properties. It purports to provide answers to a number of important “why” questions bedevilling the Standard Model: Why do particles have the masses they do, in particular why does the electron have the mass that it does? Why is it lighter than the Higgs boson? Why do forces have the strength they do? Why does the universe look the way it does? Why are there three types of leptons (electron, muon and tau)? Why not say 2, 4 or 15. The Standard Model fails to provide answers to any of these question, whereas the superparticles in supersymmetry do.
Many individual models of the universe can be “supersymmetric” if they share certain properties. For example, from symmetries themselves we have been able to derive the relation between energy, momentum and mass exemplified by E=mc². Scientists have also used symmetries to predict new phenomena. Thus, in 1930 Paul Dirac showed that when you combine quantum mechanics with relativity, spacetime symmetries imply that every particle has to have a related antiparticle – a particle with opposite charge; specifically the electron with the positron.
Supersymmentry postulates that there exists a quantum extension of spacetime called superspace and that particles are symmetric in this superspace, but it can only be correct if the universe contains a large number of superpartner particles that have eluded detection. However, to date all attempts to confirm supersymmetry, especially via the LHC, have proved elusive. Unless some experimental confirmation is forthcoming soon, to wit after the LHC has been ramped up to maximum energies (March 2015), a crisis is predicted in physics, forcing researchers to question assumptions they have been working on for decades and obliging them to cast their net wider for alternative speculative theories such as the multiverse and the existence of new dimensions. This is not the first time this has occurred in physics. As we shall see, more than a century ago, the failure to find the “luminiferous” ether led to the invention of special relativity.
Supersymmetry may also provide an answer to a baffling problem concerning the longevity of the Higgs field and the universe itself. The discovery of the Higgs boson shows that there is a Higgs energy field turned on everywhere in the universe that gives mass to elementary particles. This means that the so-called vacuum of empty space is a busy place with both Higgs energy and virtual particles producing complicated dynamics [3.1]. Is this vacuum really stable or could some unlucky quantum event one day trigger a catastrophic transition from our universe to virtually nothing. Supersymmetry acts to stabilise the vacuum and prevent such mishaps, but without supersymmetry, the stability of the vacuum depends sensitively on the mass of the Higgs: a heavier Higgs implies a stable universe, whereas a lighter one implies eventual doom. Remarkably, the measured Higgs is right on the edge in a so-called metastable state, implying a long-lived but ultimately unstable vacuum. Quantum effects could eventually bounce the Higgs field into a lower energy state, annihilating the universe in the process, but this shouldn’t happen for many billions of years[4].
The metastable Higgs field:
Once its properties are analysed, will the newly discovered Higgs particle provide any answers to these unknowns, inconsistencies and incongruities ? Does the new particle itself play a role in the inflation mechanism considered the force driving the big bang origins of the universe? And does it interact with dark matter thought to inhabit the cosmos? [5] Most physicists are hoping, Steven Weinberg among them, that something other than a common garden variety Higgs is on offer as an avenue for new vistas. If in fact the LHC fails to turn up anything on supersymmetry, it has been suggested that interest in supersymmetry as a theory may “fade away” even though it cannot be disproved[6]. The odds of its doing so (turning up) have been assessed at 50%, but some sceptics say the chances are much less[7].
[1] Davide Castelvecchi, “Is Supersymmetry Dead?’ Scientific American, May 2012, 9.
[2] Matthew, Chalmers, "The Higgs Problem- What exactly is that particle?, New Scientist, 10 November 2012, 37.
[3] The following account of Supersymmetry is an edited summary of “Symmetry and the Crisis in Physics”, by Joseph Lykken and Maria Spiropulu, in Scientific American, May 2014, 22-27.
[3.1] The nature and role of s0-called virtual particles in the context of Heisenberg's uncertainty principle is considered on the page Something out of nothing - again
[4] Lykken and Spiropulu, op cit, 26 and 27.
[5] Michael Riordan, Guido Tonelli and Sau Lan Wu, “The Higgs at Last”, Scientific American, October 2012, 58 at 65.
[6] Davide Castelvecchi, “Is supersymmetry dead?” Scientific American, May 2012, 9,10.
[7] John C Baez and John Huerta, “The strangest numbers in string theory”, Scientific American, May 2011, p 44. The 50% assessment was made by David Gross, one of the world’s leading experts on string theory.