Woit, Glashow and others on SU(5) GUT Theories

Non-detection of proton decay and other forms of baryon number and lepton number violations such as neutrinoless double beta decay and flavor changing neutral currents at the tree level, has killed countless grand unified theories, including the simplest possible one, the SU(5), which Glashow, the physicists who is largely credited with conceiving of it, has now ruled out as not viable.

Turning to physics, there’s a very good new article at Quanta from Natalie Wolchover about the unsuccessful search for proton decay and what this means for grand unification ideas. Glashow has now given up, with the simplest GUTs now conclusively ruled out: 

Glashow, for one, largely lost interest in the whole affair when SU(5) was ruled out. “Proton decay has been a failure,” he said. “So many great ideas have died.” 

Not everyone has given up though, with fans of the “flipped SU(5)” SUSY GUT explaining things this way: 

Barr, one of the originators of the still-viable “flipped SU(5)” GUT model, compared the situation to waiting for your spouse to come home. “If they’re 10 minutes late, there’s simple explanations for that. An hour late, maybe those explanations become a little less plausible. If they’re eight hours late … you begin to worry that maybe your husband or wife is dead. So the point is, at what point do you say your theory is dead?” 

Right now, he said, “we’re more at the point where the spouse is 10 minutes late, or maybe an hour late. It’s still completely plausible that grand unification is correct.” 

Besides the current wishful thinking, this particular model has a strange history. You can read here about how it follows from Vedic Science. Over the years it has been about to come home many times, see this from 2012, which assures us that: 

The CMS and ATLAS experiments have also observed tantalizing hints of the unique signature predicted by the Flipped SU(5) model. 

At this point, it seems to me to be way more than an hour late, time for its nearest and dearest to admit that it’s dead (or maybe has run off with its TM instructor).

From Not Even Wrong.