Why String Theory, Past Times Joseph Conlon

I have got received a gratuitous re-create of "Why String Theory" past times Joseph Conlon, a immature Oxford string theorist who has done successful specialized piece of work related either to the moduli stabilization of the flux vacua, or to the axions inwards string theory. (He's been behind the website whystringtheory.com, too.)

The 250-page-long paperback looks modern too tries to live to a greater extent than technical than pop books but less technical than string theory textbooks. Unfortunately, I oft experience that "more technical than a pop book" generally agency that the volume uses some sort of an intellectual jargon – but the nontrivial physics ideas aren't truly described to a greater extent than accurately than inwards the pop books.




From the beginning, ane may consider that the volume differs from the typical books that are intensely focusing on the search for a theory of everything. Well, the dedication as good as the introduction to each chapter at the showtime of the volume (and others) sort of shocked me.

The dedication remains the biggest stupor for me: the volume is dedicated to the U.K. taxpayers.




It's non exactly the dedication, however. In the preface, Conlon explains that he wants the "wonderful swain citizens who back upwards scientific query through their taxes" (no kidding!) to live the readers. He is real grateful for the money.

The preface has alone reinforced my feeling that he is "in it for the money". And the theme has continued to reappear inwards the next chapters, too. It became a distraction I couldn't acquire rid of. In at to the lowest degree 2 sections, he mentions that the fiscal resources going to string theory are much smaller than those inwards the medical query too the latter funds are soundless a tiny part of the budgets.

Great. But why would yous repeat this thing twice inwards a volume that is supposed to live virtually physics? The coin going to pure scientific discipline is modest because most taxpayers are but non interested inwards pure scientific discipline at all. They are interested inwards practical things. H5N1 minority of the people is interested inwards our pure cognition of Nature too those would pay a much higher percent of the budgets to string theory, too. The actual amounts (perhaps a billion of dollars inwards the U.S. every year?) are a compromise of a sort.

The thought that all taxpayers volition live interested inwards such a volume is empty-headed (almost equivalently, it's empty-headed to retrieve that someone volition read the volume because he is a taxpayer whose coin is partly spent for the research; most people don't read books virtually cheaper ways to hire janitors although this decides virtually billions of dollars a year, too) too it's hard for me to acquire rid of the feeling that Conlon's formulations are shaped past times the gratitude to the taxpayers for the coin – so he's sort of bribed which is incompatible amongst the scientific integrity. You may imagine that a sensitive reader such as myself reads the text too sees the deport upon of the "bribes" on diverse formulations (for example, Conlon's outrageous prevarication that all string critics are basically honest people is in all probability shaped past times the fiscal considerations – because many of the string critics are taxpayers) but quite suddenly, the volume counts the string theorists past times the release of mortgages that people have got because of some piece of work that is linked to string theory. Is that serious? And does a bulk of string theorists have got a mortgage? Whether it's right or not, why should such things matter?

The obsession amongst the fiscal aspects of Conlon's undertaking has distracted me way also often. It's totally OK when some people are considering string theory query to live exactly some other undertaking – but it is exactly non also interesting to read virtually it. We don't read books virtually the dependence of other occupations on wages, either. And for a someone who is interested inwards physics sufficiently to purchase the book, the coin circulating inwards string theory query is sure a negligible constituent of the story.

And this fiscal theme kept on penetrating way also many things. The foremost regular chapter, "The Long Wait", starts inwards June 1973. I honestly wouldn't know what lawsuit deserving to start the volume occurred inwards June 1973. It turned out that it was the appointment when the papers on QCD were submitted too inwards the book, that lawsuit is "special" from the today's viewpoint because these were the newest theoretical physics papers as of today that were awarded past times the Nobel prize. It seems technically truthful – Veltman too 't Hooft did their Nobel-prize-winning piece of work inwards 1971, Kobayashi too Maskawa before inwards 1973, too so on.

But is this factoid of import plenty to live given the total foremost chapter of a volume on string theory? I don't retrieve so. The fact that no Nobel prizes came to theoretical physicists for their to a greater extent than recent discoveries isn't truly of import – except for those who are alone doing physics because of the money, of course. But fifty-fifty when it comes to the money, numerous people (especially around string theory too inflation) got greater prizes for much newer insights. There are diverse reasons why the Nobel prizes aren't beingness given to theoretical physicists for to a greater extent than recent discoveries but these reasons don't imply that breathtakingly of import discoveries haven't been made. This focus on June 1973 is exactly a totally flawed way to retrieve virtually the importance inwards theoretical physics – an unfortunate way to start a semipopular volume on theoretical physics.

I knew that the next chapter was virtually scales inwards physics which is why I was similar "WTF" when I saw the foremost words of that chapter: "As-Salaam-Alaikum". What? ;-) This Standard Arabic greeting agency "peace live upon you". What does it have got to practise amongst scales inwards physics? Even when yous add together the next commutation from the desert that Conlon added, "where are yous coming from too where are yous going?", this commutation has soundless cipher to practise amongst scales inwards physics. At most, the commutation describes a populace draw inwards an Arab part of the spacetime. But it has cipher to practise amongst the renormalization group. Perhaps both situations involves diagrams amongst oriented lines – but that's also little an amount of mutual ancestry.

Again, ane can't avoid thinking: this awkward showtime was in all probability a not-so-hidden message to the Muslim British taxpayers. Sorry, I have got a employment amongst that. And I retrieve that so practise the Muslim Britons who truly aid virtually physics. And no British Muslim volition purchase a volume virtually string theory because it contains an Standard Arabic greeting so this sort of bootlicking is ineffective, anyway. The volume of the chapter dedicates many pages to describing the size of many objects. I retrieve that what makes it irksome is that Conlon doesn't seem to communicate whatever deeper too nontrivial – or, almost equivalently, a priori controversial – ideas (something that books similar Wilczek's volume on beauty are total of). It seems to me that the volume is addressed to some moderately intelligent people amongst superficial ideas virtually physics too it encourages them to retrieve that they're non truly missing anything important. The logic of the renormalization group, "integrating out", or its relationships amongst reductionism etc. aren't truly discussed.

The following, 3rd chapter wants to encompass the pillars of 20th century too pre-stringy physics. It starts past times talking virtually special relativity. Conlon argues that the words "In the beginning..." inwards the Bible (as good as the whole dependent area of history etc.) contradict relativity. Sorry, in that location isn't whatever contradiction similar that. Even inwards relativity, ane may sort events chronologically. Different observers may practise so differently but it's soundless possible. And inwards the history of events on the Earth, the spatial distances are so brusque relatively to the times times \(c\) (and the reasonable velocities to consider are so much smaller than the speed of light) that all the observers' choices of the coordinates terminate upwards beingness basically equivalent, anyway. So the reference to the Bible has cipher to practise amongst special relativity, exactly similar the Standard Arabic greeting that had started the previous chapter has cipher to practise amongst scales. Perhaps it was a message to the Christian taxpayers. Or the vehement atheist taxpayers – because the comment virtually the Bible was a negative one.

Now, a page is dedicated to special relativity too less than a page to foundations of full general relativity. It's truly also fiddling too cipher is truly explained there. Moreover, full general relativity is framed as a "replacement" of special relativity. That's non correct. Einstein would pull it as a generalization, non replacement, of special relativity (look at the name), relevant for situations inwards which gravity matters. In the modern setup, nosotros stance full general relativity as the unique framework that results from the combination of special relativity too spin-two massless fields (which are needed to comprise gravity). In this sense, full general relativity is an application of special relativity – too inwards some sense a subset of special relativity.

Quantum mechanics is given several pages too Conlon says that it absolutely plant which is goodness news. But aside from a few sentences virtually the quantum entanglement, the pages are generally spent amongst repeating that quantum mechanics is needed for chemistry. There are several to a greater extent than sections virtually the pre-stringy pillars of physics – some cosmology, something virtually symmetries.

The 4th chapter wants to debate that something beyond the Standard Model too GR is needed. So it's the chapter mentioning the non-renormalizability of gravity etc. Some of import points are made, including the dot that quantum mechanics must handgrip universally (Conlon sure is pro-QM). But I can't consider what sort of readers (with what background) volition empathise the explanations at this level. The explanations vaguely depend on some quasi-expert's jargon but they don't say plenty for yous to reconstruct whatever actual arguments. I've done lots of this semi-expert writing too it seems absolutely obvious to me that yous demand to extend the semi-technical explanations at to the lowest degree past times an fellowship of magnitude relatively to Conlon's brusque summaries to truly convey some helpful, verifiable, usable, nontrivial ideas.

If I essay to characterize the people who are waiting for this genre that is linguistically heavy but lacking the actual arguments, I retrieve it's right to say that they're "intellectuals who are create to parrot sentences, fifty-fifty complicated sentences amongst the jargon similar to the experts' jargon, to defend their intellectual credentials (i.e. print other people amongst intelligently sounding sentences)" but who don't truly empathise anything properly. And I retrieve it's non right to increase the release of such people.

Thankfully, things acquire ameliorate from the 5th chapter that begins amongst string theory proper. The foremost lawsuit is Veneziano's piece of work inwards 1968. Conlon describes virtually 10 non-physics events inwards the twelvemonth 1968. It's non clear to me why in that location are so many events similar that. But inwards such a long list, I retrieve it is crazy non to cite Prague Spring inwards Czechoslovakia (and the educatee riots inwards Paris should live featured to a greater extent than prominently, too). It ended on August 21st, 1968 when 750,000 Warsaw Pact troops occupied my country. To say the least, it was the largest armed services functioning since the state of war which, I believe, is to a greater extent than of import than the cancellation of final steam engines on British railways etc.

The populace canvas duality that was deduced from Veneziano's formula hides some cool mathematics but the volume unfortunately avoids equations so none of this content is communicated. The beauty too mightiness of all these things may alone live understood along amongst the mathematical relationships etc. which is why I am afraid that this "more detailed" but purely verbal story virtually the discoveries doesn't convey much to a thinking reader. It's similar a volume praising a beautiful paradigm – which doesn't truly exhibit yous the painting.

There are diverse stories, e.g. virtually Claude Lovelace who realized that bosonic string theory requires 26 dimensions. Lovelace has never completed his PhD but he was hired as a professor at Rutgers, anyway – I was coming together him for many years when I was a PhD educatee (he died inwards 2012). H5N1 quote inwards Conlon's volume suggests that Lovelace's advertisement was insufficient relatively to his contributions. I wouldn't handgrip amongst that. At Rutgers, I also knew Joel Shapiro, some other early on virile someone raise of string theory. He's a fun guy – he taught grouping theory to us. H5N1 real goodness course. At a colloquium I gave later, he suggested that the term "first string revolution" should indeed live used for the 1968-1973 era, as Conlon indicates. Whatever is the right cry (I called it the zeroth string revolution), it wasn't a superstring revolution because in that location was no supersymmetry yet!

What seems problematic to me is that the exact chronology of the historical events became the heart of Conlon's prose. But string theory isn't a collection of random historical events, similar the Second World War. It's primarily a unifying theory of everything that nosotros don't empathise perfectly but the electrical flow incomplete understanding is much to a greater extent than accurate too makes much to a greater extent than sense than what people knew inwards the belatedly 1960s, or inwards the next 4 decades. H5N1 volume that is truly virtually physics exactly can't position all historical events on the same level. The history was exactly virtually the "Columbus' journeying to the New World" but it's the New World itself, too non details of the journey, that should live the dot of a volume "Why the New World".

Various discoveries too dualities etc. are mentioned inwards ane or 2 sentences per discovery. I retrieve it's exactly also fiddling information virtually each of them. It may live OK for people who read dozens of redundant books a twelvemonth too who don't experience the urge to retrieve virtually every thought that is beingness pumped into them. For sure reasons, I retrieve that it's counterproductive when people larn virtually also many facts virtually string theory (or some other theory) without truly understanding their human relationship too inevitability. If they larn many things, they must experience that string theorists are exactly inventing random garbage. It feels similar scientific discipline could alive as good without those things (if the events were replaced past times totally unlike events amongst a unlike outcome) – exactly similar the mankind could have got survived without the Second World War. But it isn't the case. They're deducing something that can't live otherwise – a dot yous may alone verify if yous truly know the technology. Well, at some moment, yous may start to trust claims virtually exact dualities etc. past times sure authors. But yous must consider the rigid bear witness for or a derivation of at to the lowest degree ane such an amazing final result (or several) to consider that it's non exactly a pile of fairy-tales.

While e.g. Richard Dawid exaggerates (to say the least) the changes inwards thinking during the string theory era, he does correctly capture the importance of uniqueness (only game inwards town) too unexpected explanatory interconnections for the string theorists' focus on string theory. Conlon, piece a string theorist, seems to completely overlook if non explicitly spend upwards these facts too principles. But they're essential for the understanding where theoretical physicists volition facial expression for novel insights inwards the time to come too how they exercise the accumulated cognition to regain the novel one. So the vision or motivation for the time to come is so basically absent inwards Conlon's book, too.

Another chapter is virtually AdS/CFT too the landscape. AdS/CFT was revealed inwards 1997 – too exactly similar for 1968, Conlon lists many events inwards 1997. Tony Blair won some elections inwards a landslide. Holy cow. Every year, in that location are hundreds of elections inwards the populace too someone wins them. Even the elections inwards the United Kingdom of Great Britain too Northern Ireland of Britain too Northern Republic of Ireland are rather frequent. Moreover, I don't empathise the logic past times which a volume similar this ane should live preferably read past times the Britons only. The scientific curiosity is transnational. The volume may live "dedicated" to United Kingdom of Great Britain too Northern Ireland of Britain too Northern Republic of Ireland taxpayers but if it's virtually science, too so it must live as interesting for the Canadian too other taxpayers, right?

But in that location are to a greater extent than serious bugs amongst the content, I think. We're told that after AdS/CFT, almost no ane would stance string theory primarily as a unifying telephone commutation theory of Nature. Sorry but that's rubbish. Virtually all top string theorists do. The fact that in that location are lots of articles that exercise AdS/CFT methods exterior "fundamental physics" doesn't imply that the links of string theory amongst telephone commutation physics have got been weakened. You may regain millions of T-shirts amongst \(E=mc^2\) which doesn't hateful that it's the most of import insight made past times Einstein.

Similarly, it's incorrect to say that the AdS/CFT made string theory "less special". The AdS/CFT correspondence has found a novel powerful equivalence betwixt string theory too quantum land theory – but the 2 sides operate inwards unlike spacetimes or populace volumes. This holographic duality has made string theory to a greater extent than "inseparable" from the established physics too it became less conceivable that string theory could live "cut" away from physics over again – it's because dynamics of string theory inevitably emerges if yous report the of import established theories, quantum land theories, carefully plenty (especially inwards sure limits).

But if yous exercise a consistent description, it's truthful (just similar it was truthful before AdS/CFT was found) that inwards whatever spacetime where yous tin consider the effects of quantum gravity, yous may also consider something similar strings or M2-branes too the extra dimensions (for the total to live 10 or 11) too other things that come upwards amongst them. AdS/CFT doesn't allow yous to circumvent this fact inwards whatever way. It alone gives yous a novel description of this physics of strings or membranes inwards price of a theory on a different space, the boundary of the AdS infinite – a novel QFT-based tool to straight test that in that location are strings, branes, too diverse other stringy effects inwards the bulk. This theory on the boundary happens to live a quantum land theory. But the importance of QFTs inwards string theory wasn't new, either. Perturbative string theory was ever described inwards price of a QFT, namely the two-dimensional conformal land theory. The essential dot is that this 2D CFT lives on a unlike space, the populace sheet, than the actual spacetime where nosotros notice the gravity. Aside from the populace canvas CFT, AdS/CFT has also told us to exercise the boundary CFT – some other QFT-style way to pull stringy physics. But the physics of quantum gravity inwards the same spacetime as the spacetime of quantum gravity is as stringy as it was before. AdS/CFT has allowed us to explicitly build many phenomenologically unrealistic sets of equations for quantum gravity (by constructing some boundary CFTs) but it hasn't made the employment of combining particular non-gravitational affair contents amongst quantum gravity less constraining. An ordinary generic QFT used as a boundary CFT produces a "heavily curved gravitating AdS spacetime" too those may have got acquire "easy" inwards some way. But the actual, low-curvature theories of quantum gravity are as rare as before.

At least, I found Conlon's give-and-take of the landscape OK. The large release of solutions is neither novel non a problem. The anthropic regulation is non-vacuous but it may easily degenerate into explanations that may facial expression sufficient to someone but that are demonstrably non the right ones.

In some other chapter, Conlon starts to verbalize virtually the "problem of rigid coupling". I am afraid that the basic thought that "something is slow at weak coupling, hard at rigid coupling" etc. is real easy, much similar the usage of the buzzword "nonperturbative". But people who don't truly empathise too who misinterpret what "easy" too "hard" too "nonperturbative" hateful volition practise so after reading these pages past times Conlon, too. Conlon continues amongst the give-and-take of the high release of citations of AdS/CFT too reasons why it's exact too correct. An exact understanding virtually a complicated polynomial-in-zeta-function formula for the dimension of the Konishi operator for many colors makes a lesson clear.

Many pages verbalize virtually the application of AdS/CFT correspondence to heavy ion physics; the adjacent department similarly talks virtually AdS/condensed affair physics. There are many truthful facts too factoids there. I disagree amongst Conlon's decision inwards the heavy ion department that adding corrections on top of simplified models is the universal "modus operandi" of science. He uses this thesis to explicate that the "exact AdS theory" of the heavy ion physics has to live supplemented amongst corrections for it to work. That's truthful too it's normal inwards much of physics but 1) it is ever preferred inwards physics when adjustments don't have got to live added, too 2) it is not how string theory inwards the strict sense works. String theory does not allow ane to add together whatever continuous corrections to its physics, ever. Everything is completely determined past times discrete information (identifying the vacuum solution) too the fact that the adjustments are possible inwards AdS/heavy ion physics shows that those methods are exactly string-inspired, non examples of full-fledged string theory.

The adjacent chapter talks virtually the interactions betwixt physics too mathematics. It starts amongst the pride of physicists. Physics is the deepest scientific discipline too physicists are Sheldon. No ane else tin gibe them – peradventure amongst the exception of mathematicians. Some insights too facts virtually mathematics are picked (perhaps a flake randomly) but the chief dot to live discussed is the catamenia of ideas inwards betwixt mathematics too physics.

Monstrous moonshine too mirror symmetry are discussed as the 2 large examples of string theory's importance inwards mathematics (excellent topics except that ane can't consider the beauty without the mathematical "details") piece the adjacent department argues against "cults" too chooses Feynman too Witten as the 2 "cults" that should live avoided. (I retrieve that Witten's cult is basically non-existent, at to the lowest degree exterior 3-4 buildings inwards the world, too I would say "unfortunately".) Progress since the 1980s wouldn't have got taken house if everyone were similar Feynman; or everyone were similar Witten, Conlon says. I truly disagree amongst both statements. Diversity is way also overrated here. If yous had 1,000 Feynmen inwards physics inwards the 1980s, I am pretty sure that they would have got found the things inwards the foremost superstring revolution, too, aside from many other discoveries. One can approach all these things inwards Feynman's intuitive way. And Conlon overstates how "just intuitive" Feynman papers were. He could have got made discoveries amongst easier formulae because he was usually making telephone commutation discoveries. But he was the foremost guy who systematically calculate the Feynman diagrams – from the path integrals to the Feynman parameterization, \(bc\) ghosts that Feynman de facto invented, too beyond. This is inwards no way "just heuristic/intuitive science".

The disadvantange of Feynman inwards the existent populace was that in that location was alone one. Things are fifty-fifty clearer amongst Witten. I don't handgrip amongst Conlon that Witten is alone goodness at things that are "at the intersection of mathematics too physics". Witten has done lots of phenomenology, too, including things similar cosmic strings, SUSY breaking patterns, detailed calculations on \(G_2\) holonomy manifolds. 100 Wittens too no ane else since 1968 would have got been plenty to regain basically everything nosotros know today. People are unlike too may have got unlike strengths but that doesn't hateful that most of these idiosyncrasies are irreplaceable. It tin accept to a greater extent than endeavour for someone to regain something – than it takes to someone else – but scientific discipline ultimately plant for everyone who is sufficiently intelligent too hard-working. To say otherwise agency to believe that scientific discipline depends on some magic unreproducible skills.

Chapter 10 is meant to focus on Conlon's characteristic query topics – stabilization of the moduli inwards compactifications too axions. You may imagine that ane needs to know quite a lot to follow what e.g. his papers could have got contributed. I retrieve it's basically impossible to convey the information inwards a semipopular volume but he tries. The next Chapter eleven is virtually quantum gravity inwards string theory – Strominger too Vafa etc. It doesn't acquire to recent, post-2009 advances, as far as I tin see.

Another chapter argues that all styles of doing physics – revolutionaries too hard workers etc. etc. – are important. It may audio OK but inwards reality, it's non truly possible to carve upwards most physicists past times their styles into these boxes at all. Whether someone makes a revolution is ultimately not virtually his styles too emotions, anyway. And as I said, goodness physicists may "emulate" what others are doing, despite their having unlike methods too styles.

The next chapter does a pretty goodness undertaking inwards replying some mutual criticisms of string theory. Then in that location is some other chapter where it's discussed e.g. why loop quantum gravity has remained unsuccessful. I don't retrieve that Conlon describes the condition of that proposed theory accurately.

There's a lot of facts too ideas to live found inwards this volume too I evidently handgrip amongst a large part of it. But because of the combination of the "difficult language" too "shortage of actual explanations amongst the beef", the target audience isn't clear to me, the text seems to live driven past times fiscal too career-wise considerations at also many places (and many of us regain these sociological etc. things to live also distracting), too it doesn't displace into the sufficient depth for the reader to truly empathise that string theory isn't a conglomerate of randomly invented ideas that people are adding arbitrarily (even though Conlon knows real good too explicitly writes that string theory cannot live described inwards this way). It is non truly a volume that explains something hard plenty (for the layman or the non-expert scientist) too I retrieve that Conlon isn't truly an "explainer" inwards this sense. And I fifty-fifty retrieve that the volume reinforces some misconceptions spread past times some critics of string theory (e.g. virtually the deport upon of AdS/CFT on the condition of string theory as a TOE).

You may desire to purchase the volume anyway, to consider that it's peradventure non as bad as this text makes it sound.