In a literal sense, a new theory, in this case involving dark energy and the Higgs Boson, by two well-known physicists – Lawrence Krauss and James Dent – is “news.” So why did I question my first reaction to create a ‘news’ story? Well, new theories of any kind, much less in the theory-filled universe of cosmology, are plentiful and most of them never make it far enough onto anyone but a specialist’s radar. So what was different about this one? Three things, I think.
One, dark matter and dark energy are of the greatest mysteries. This is certainly true for cosmology and astrophysics, but really for the whole of science. Scientists currently believe that dark energy constitutes about 70% of the total energy density of the universe (2-5% is observable matter/energy, 25% dark matter). Yet for all its supposed ubiquity, dark energy remains a hypothetical construct. As yet, there is no fully satisfactory evidence (much less proof) of its existence. It’s vastly important, yet remains a profound mystery. Serious attempts at explanation are potentially very important.
Two, the scientists involved with the new theory, which they dub “Higgs Seesaw Mechanism as a Source for Dark Energy,” are long-time researchers in the area of dark energy and the cosmological constant. They have cred among their peers. However, they have also authored books and papers (such as Krauss’s The Universe from Nothing), which made best-seller lists (suck air through teeth in reaction) and generated a fair amount of controversy. This includes their notoriously mis-interpreted notion from 2007 that humanity’s observation of dark energy would doom the universe (or some such thing). In short, with Krauss and Dent you get a mix of very serious astronomical research with a dose of the popularizer. This mix makes some people in the scientific community uncomfortable.
Three, reputations aside, the theoretical proposal Krauss and Dent make is interesting, if only because it can be expressed without resorting to obfuscation by jargon. It goes something like this: When the Large Hadron Collider demonstrated the existence of the Higgs boson; it opened the door to verifiable speculation about its potential connection to dark energy. The Krauss and Dent paper, published in Physical Review Letters [09 August 2013, paywalled] makes a case for a small coupling between the Higgs boson and possible new particles (to be discovered) existing at the “Grand Unified Scale” – an infinitesimal scale 16 orders of magnitude smaller than a proton, a scale at which the three known non-gravitational forces might converge into a single theory. These particles, if they exist, could each have an energy field similar to the seesaw (fluctuating) property of the Higgs field. Taken together, the Higgs boson and the related particles could contribute enough energy density to account for the presumed density of dark energy.
The Krauss-Dent paper is at pains to make it clear their hypothesis has defensible or even testable elements, but it is a long way from a convincing argument. In fact, it is only a first step in constructing a theoretical framework for what may – or may not – turn out to be a new level of particle physics. In other words, the ideas in the paper are backed with workable mathematics, but are still in essence part of a thought experiment. We’ll see what others in the field make of it, or not, in the meantime.