35 Years Of Losing At Particle Dark Matter Roulette

Particle physicists are supposed to be the best and brightest, but one begins to wonder when one sees their track record at trying to identify Nature’s actual dark matter objects.

In the 1980s theoreticians came up with the Cold Dark Matter Model of the cosmos, which required particle dark matter. Between roughly 1985 and 2020 there have been an average of 10 to 50 tests per year, and this is a conservative guess. That makes a rough approximation of 350 to 1750 experimental tests of the particle dark matter hypothesis, and 1000 may be a more realistic minimum number. The number of papers written on the particle DM hypothesis over that 35 year period is enormous and the number of equations devoted to it is astronomical. The expenditures on this snipe hunt have been jaw-dropping.

A partial list of the major candidates would include: neutrinos, sterile neutrinos, axions, neutralinos, Sneutrinos, gravitinos, light scalar particles, axinos, Little Higgs particles, and superheavy particle.

Because particle theorists had little idea about the details of what they were looking for (like their crucial putative mass values) they had a vast parameter space to play in. The problem is that every experiment yielded negative results or false positives “hints” that were quickly disavowed.

So have particle theorists soured on the idea of particle dark matter? Hardly! Most seem to have doubled down and pressed on into the Big Muddle. ‘Surely the next experiment with a bigger machine will find them’ is their mantra.

Meanwhile the observational evidence for stellar-mass primordial black holes has grown steadily, as has interest in this novel dark matter candidate.

Scientists are evidence-based and rational. Right?