The researchers faced difficulties advancing their theory because Physics has virtually given itself over to String Theory. Smolin et al kept it up, searching for the elusive graviton... ( )

The paucity of popularizations of loop quantum gravity -- a major attempt to unify quantum theory and general relativity by discretizing spacetime itself -- makes this volume a welcome addition to the large set of books on fundamental physics. It strongly focuses on the efforts -- both collaborative and separate -- of Lee Smolin and Carlo Rovelli to develop and apply the theory. In describing how the two men now (respectfully) differ on such issues as the nature of time and the interpretation of quantum mechanics, it helped to clarify my personal feeling that Rovelli's positions are the more convincing. A writing-style alert: Baggott very often uses "which" instead of "that" as a restrictive relative pronoun.

“Now, through the efforts of a number of dedicated theorists, a resolution appeared to be at hand. Remember, this was a theory [LQG] that drew all the lessons about the nature of space and time from general relativity into a structure that closely resembled a quantum field theory. It produced a set of equations that could be solved without the need for messy and tedious renormalization procedures, and whose solutions could be shown to be completely independent of any choice fo coordinate system - it was genuinely independent of any kind of spacetime background. What’s more, this was a theory founded directly on accepted , empirically tried-and-trusted structure - there had been no need to second-guess physical reality any further by introducing supersymmetries, or hidden dimensions. But any jubilation that the theorists [Smolin, Rovelli, etc.] might have experienced was shortlived. Because, just a few months before Rovelli and Smolin’s paper was published, some statements delivered to a conference by Edward Witten sparked a second revolution [String Theory].”

In “Quantum Space - Loop Quantum Gravity and the Search for the Structure of Space, Time, and the Universe” by Jim Baggott

“M-Theory is not a theory. To this day, nobody knows what M-theory looks like, although many theorists have tinkered with structures that they believe it could or should possess.M-theory is really the presumption that there must exist a unique, eleven-dimensional superstring theory.”

In “Quantum Space - Loop Quantum Gravity and the Search for the Structure of Space, Time, and the Universe” by Jim Baggott

Firstly, there is a limited number of top quantum/relativity scientists in the world. This fact is extremely important, because a big portion of those work on M-theory with the rest working on LQG (I’m exaggerating, but you get the gist). People argue that M-theory is so complex that you need many of the top minds working on it (are they?), BUT that actually limits the brain resources for the rest of the fields. And I do not only mean science, but also ideas that could one day lead to science.
One of that majorities’ main argument is, quantum physics has hit a roadblock last 30 years, only discovered things that was more or less already expected, and only real progress come from astronomy. Well, if old experts keep saying that to young students, they are going to choose something like M-theory, and they don't want to devote their career on something that has no promise of big breakthroughs. But younger generations have often in science history come up with radical new ideas that can make a stale field move forward. Well, that might take a long time now that many of the brightest works on M-theory.

And another thing. Even if M-theory can be applied to our universe(s), it looks to be a long way from science. People often say M-theory is like next centuries science, by accident discovered in the last. Well, it sure looks that way, also in terms of when it will become science. Likely not next 10 years or 50. As far as I understand, it does not even have the string equivalent of fields yet. And, with the 10^500 permutations of possible universe configurations, it’s not even sure it will ever be useful, even if does fit the world we live in.

I am not saying it should be thrown away, it just vacuums too many bright minds away from other fields like LQG.

As my father used to say, one step at a time, i.e., not all the steps at once, is what I vote for. Cannot force LQG on people; people should research what they feel like. Like doing more research into Grand Unified Theory (GUT), instead of trying to skip directly to Theory of everything (TOE), like M-theory. I just think it’s a problem, and a big one.

Many scientist working in quantum theories, often also believe in M-theory, even though it is not the field they work in. That could also be a problem, as they might for example think, "hmm, I would not spend my time on GUT, as M-theory will be the theory on that". Which would also limit competing theories on aspects M will cover.

First place to start; top m-theory experts should stop trying to paint opponents of M-theory as crackpots (I’m one of those crackpots). It's not done directly, but can often be read between the lines. And stop calling it science, until it is. I hope this gets better, so science can move forward faster. I see only one reason to stop progress, that is if the scientists suspect new insight can lead to unwanted weaponization. Like antimatter bombs or something similar that is too powerful for us to handle. Then of course scientists should find ways to prevent progress in that field. But this does not seem to be the case, so please let’s get more research diverted from M-theory into improving our current framework of nature, so we can understand dark matter/energy, and other weird empirical data from the universe.

The entire basis of any 'theory of everything' is the rather presumptuous notion that what we can currently observe IS actually 'everything'. If we have actually only uncovered 1% of what exists, then we'd be in the absurd position (which I think we actually are) of trying to find an 'all-encompassing' theory that left the bulk of reality unexplained.

My suspicion is that the reason why quantum theory and gravity (LQG) have yet to be unified is not for lack of mathematical geniuses but because the lack of unity suggests there is more physical reality that we have not yet arrived at. Only when we find the missing physics will we stop trying to fit a square peg into a round hole. It is true that one has the impression that science at the present cutting edge is rather theory rich and data poor. However, I suspect that this is always the case, because at the frontier of science it is usually easier to theorize than to gather and interpret data. As the frontier moves on, unsuccessful theories fall by the wayside and are forgotten. We thus suffer from a sort of historical tunnel hindsight in which we see the path that science has traversed as an obvious high road, and forget that it was usually far from obvious at the time.

At the end of the day there is no problem with spinning all kinds of theories, because ultimately the facts will decide the issue. Scientists know that. There's no downside. Nobody is about to take string theory or whatever as fact and base their actions on that.

Jim Baggott has written an honest book, while some String Theorists (e.g., Susskind and Greene) have fought many fights in blogsphere and exploited journalists as far as it goes. It is hilarious how they exploit quantum information to support string theory while privately, string theorists consider colleagues working with quantum information as dumb-fucks who tailor with trivial finite dimensional matrices. Esteemed Professors Susskind and Greene, don't steal others horses when your own old cow gets tired! ( )