- string theory
- loop quantum gravity
- causal dynamical triangulation
- quantum Einstein gravity
- quantum graphity
- internal relativity
The remaining ones, with loop quantum gravity being the intermediate case, are fringe theories with 10-30 citations (from other crackpots) in average. When combined (and when LQG is omitted, just to be sure), they are more than 1,000 times smaller contribution to science - and especially the task to find the theory of all elementary forces and particles - than string theory.
I can't believe that Mr Marshall isn't capable to see this point and that it's simply not true that there are "six competitors" of string theory in any sensible or useful sense.
In the string theory section, the readers relearn all the opinions by the weak minds such as Peter Woit and Lee Smolin that have intensely spread in the media 4 years ago. There's no actual meaningful information about this key pillar of state-of-the-art theoretical physics, just the usual crackpot flapdoodle that it is bad to have XY solutions instead of UV solutions.
All the other theories including LQG can be falsified by a competent physicist within minutes - because of their incompatibility with the observed Lorentz symmetry, with the existence of fermions, flat space, unitarity, diffeomorphism symmetry, anything that matters in physics. Of course, we don't learn about any of these inconvenient facts.
But some of the entries are really juicy. For example, one of the "theories of everything" is quantum graphity, based on the permutation group of events in spacetime. First, the article incorrectly attributes this idea to Fotini Markopoulou even though it was proposed by Phil Gibbs in 1995: preprint. At any rate, there's no reason to struggle for priority because the idea manifestly cannot work.
The journalists seem completely incapable to understand any technical arguments, not even simple ones, so let me try some sociological ones. Gibbs' 1995 preprint has 26 citations, the Markopoulou et al. 2006 preprint has 29 citations. That's pretty bad for "theories of everything" because the figures are below (or close to) the average for any preprint - and there are tens of thousands of them in the field.
Or does Mr Marshall really believe that he is more likely to guess which preprint contains the theory of everything than the physicists?
Similarly, "internal relativity", another "theory of everything" originally called emergent general relativity, has 20 citations. Garrett Lisi's "exceptional theory of everything" based on E8 has 13 citations at this moment, despite the infinite hype in the media that tries to hijack the scientific research, too. You can also see that those newer follow-ups haven't led anywhere themselves. All these research directions are dead ends and all the citations are a matter of a "political support", not a real usage of the ideas others to achieve something of value.
Mr Marshall also seems to be incapable to understand that the exceptional group E8 has been known since the 19th century and it's been omnipresent in high-energy theoretical physics (and especially in discussions of stringy unifications) since the 1985 discovery of the heterotic string, so the group itself has nothing to do with the "surfer dude" who doesn't even know the basic subgroups of this Lie group.
In order not to use any other people in my argument, let me mention that e.g. my average preprint has had 65/73 citations, with the top-cited one near 250 citations. The last number, by itself, is more than all the last five "theories of everything" in the Nude Socialist list combined. Is that really so difficult to understand that this not-so-subtle hint could actually mean something?
I just find it incredible that a magazine that claims to be a popular science magazine keeps on promoting complete garbage and nonsense all the time so that real science is already hidden under megatons of shit. What they are - systematically - doing is a big disservice to science.
Physics is not an enterprise where every ambitious crackpot who screams to have a theory of everything is instantly on par with the most important research program in the contemporary pure science. Science is not an "anything goes" business.
First, the misleading reporting helps to increase the gap between the real scientists and the interested public which is bad by itself. Second, the young people who get attracted to physics will later find out that all these statements about the alternative possible theories of everything were just lies, which really means that 6/7 of the people who would get to physics because of similar articles will just suffer because they will find themselves as "preprogrammed" for the research of something that doesn't make any sense.
It always hurts to promote opinions that are not true.