Natalie Wolchover wrote a Quanta Magazine story
Where Gravity Is Weak in addition to Naked Singularities Are Verbotenwhich is promoting about fun May 2017 piece of work past times Jorge Santos (Prof) in addition to Toby Crisford (student, both Cambridge UK). I guess that but similar inward many other cases, the ground why a pop article was scheduled was that the Feb 2017 preprint (which has almost 1 citation thus far) has late appeared inward a prestigious printed journal:
Violating the Weak Cosmic Censorship Conjecture inward Four-Dimensional Anti–de Sitter Space (PRL; arXiv)They considered GR coupled to electromagnetism – the Einstein-Maxwell organization – inward \(AdS_4\) in addition to found a counterexample to the 1969 Cosmic Censorship Conjecture past times Roger Penrose. It's the electromagnetic forcefulness that allows them to arrive at the consequence (which Penrose considered forbidden) with the naked singularity. And they debate that just when the 2006 Weak Gravity Conjecture past times ArkaniHamed-Motl-Nicolis-Vafa is obeyed, the cosmic censorship volition live on defended in addition to the pathological singularity volition live on hidden inside a dark hole.
Well, I mean value that Santos in addition to Crisford wrote that the inequalities for cosmic censorship in addition to that of the weak gravity conjecture are solely the same upward to a numerical constituent that may neglect to live on one, in addition to that may neglect to live on theory-independent, thus I mean value that the "precision" of the equivalence is overstated inward Wolchover's article. But let's ignore this technicality: the fossil oil claim is that the \(AdS_4\) theory coupling electromagnetism in addition to gravity volition live on defended against the bad, naked singularity if in addition to solely if gravity is the weakest forcefulness (if at that spot be charged particles whose electrostatic forcefulness trumps the gravitational one).
But piece Wolchover wrote a lot of interesting things nicely in addition to accurately, at that spot is about basic confusion almost basic qualitative issues inward her text, too.
So first, let's review about basics. When nosotros formulated the Weak Gravity Conjecture, nosotros had about evidence based on clever semi-heuristic arguments inside full general quantum gravity, sort out of controlled gedanken experiments similar to those that Einstein in addition to Bohr discussed inward their debates almost quantum mechanics. And nosotros had anecdotal evidence based on the fact that the inequality seems to live on obeyed inward string/M-theory.
Even though Crisford in addition to Santos used numerical techniques inward GR, their add-on to the back upward of the Weak Gravity Conjecture must live on counted every bit about other semi-heuristic argument, in addition to an interesting one.
Our semi-heuristic arguments derived the Weak Gravity Conjecture from the requirement that dark hole remnants must live on absent; near-extremal charged dark holes must live on unstable; in addition to approximate symmetries imitating the (forbidden inward quantum gravity) global symmetries also good should amend live on banned. Some of the 300 followups bring linked the inequality to about other interesting, well-motivated, in addition to seemingly independent conditions.
Crisford in addition to Santos add together an exciting novel one. If nosotros had known almost this calculation inward 2006, their newspaper could bring cash inward one's chips about other chapter of the newspaper in addition to the listing of authors could bring had half dozen members. ;-) If at that spot are extra forces that are much weaker relatively to gravity, 1 may occupation them to degree singularities – singularities unprotected past times an trial horizon. Many people mostly believe that women on the street shouldn't ba naked, in addition to neither should live on well-behaved singularities inward a well-behaved Einsteinian theory of gravity. Both assertions are somewhat normative inward character; they haven't genuinely been proven. But Crisford in addition to Santos dot that this claim almost the "etiquette of singularities" isn't independent from about other, to a greater extent than justified rules inward physics.
To derive the status whether the electromagnetic forcefulness is stronger than gravity, every bit required past times the ban on the naked singularities in addition to past times the Weak Gravity Conjecture, yous ask about sort of a unification of these ii forces. Your theory should amend handgrip that their strength may live on "the same" inward about right quantification. So theories without whatever unification of gravity with other forces volition almost certainly neglect to enforce the Cosmic Censorship Conjecture.
Loop quantum gravity is an example. People who promote this šit bring repeatedly said that yous tin but add together electromagnetism on summit of their infantile version of aether irrationally claimed to resemble Einstein's gravity in addition to the coupling is unconstrained. If that's so, this LQG+Maxwell volition sometimes enforce the cosmic censorship, sometimes violate it.
So Nima Arkani-Hamed is quoted every bit maxim "If the weak gravity conjecture is right, loop quantum gravity is definitely wrong". Thanks for that, Nima. Well, Nima's thoughts almost loop quantum gravity bring been real similar to mine for decades but I am pretty sure that it's the get-go fourth dimension yous were told that Nima could dare to mean value that loop quantum gravity is wrong, non a existent competitor.
Funnily enough, Lee Smolin, a loop quantum gravity dog, told Wolchover that "if the Weak Gravity Conjecture is true, at that spot volition live on a loopy ground for it". This is but about other amazing instance of Smolin's brutally unscientific methodology. No derivation of the Weak Gravity Conjecture from loop quantum gravity is known in addition to it seems almost obvious that none may be because about constraint on the strength of the ii forces requires about "unification" of these forces in addition to loop quantum gravity's traveling salesmen mostly tell that the right theory, theirs, doesn't comprise whatever "unification". So Smolin uses about hypothetical newspaper that doesn't be in addition to likely cannot be inward lodge to do the impression that inward this cosmic censorship test, loop quantum gravity managed to necktie string theory in 1 trial again.
Sorry, it didn't. If cosmic censorship is viewed every bit a "nice thing", in addition to then the corresponding required inequalities bring been shown to handgrip inward string theory, but they haven't been (and they likely cannot be) shown to handgrip inward loop quantum gravity. So the comparing of string theory in addition to loop quantum gravity is sure enough not a tie. Like inward dozens of previous comparisons, string theory won, loop quantum gravity lost, in addition to you're but a pile of dishonest lying garbage, Mr Smolin. Unrealistic promises but aren't equivalent to results. And piece people are finding interesting results, yous bring done nil valuable inward your life, Mr Smolin, piece your demagogy solely impresses the to the lowest degree demanding laymen if I avoid the term filth.
But I was genuinely shocked past times a declaration that Wolchover wrote herself, too:
Such an alliance with the better-established cosmic censorship conjecture would reverberate real good on the weak gravity conjecture.Oh, thus the cosmic censorship conjecture is "better-established" than our conjecture? And yous limited this sentiment inward a pop article whose primary operate is to explicate the novel newspaper past times Santos in addition to Crisford? Let me get upward that the get-go judgement inward the abstract of the Crisford-Santos paper says:
We consider time-dependent solutions of the Einstein-Maxwell equations using anti-de Sitter (AdS) boundary conditions, in addition to supply the get-go counterexample to the weak cosmic censorship conjecture inward iv spacetime dimensions.So if yous genuinely honor the results of the newspaper yous were supposed to explain, the Crisford-Santos paper, the cosmic censorship conjecture isn't better-established. It is wrong. The folks found a counterexample. Wolchover is practiced but surprisingly, she was inward a minority of writers who got this dot incorrectly. Most of the dozen of thus of tidings reports almost the Santos et al. newspaper did realize, fifty-fifty the title, that they bring invalidated Penrose's conjecture.
Theirs is genuinely real far from the get-go counterexample to Penrose's conjecture. First, the master copy version of the "cosmic censorship conjecture" was stronger in addition to was shown to live on invalid real quickly. So it was weakened – non genuinely once, inward fact – in addition to that's why Crisford in addition to Santos, every bit good every bit others, solely bargain with about "weak cosmic censorship conjecture". But fifty-fifty this weakened version has been known to live on violated higher upward iv spacetime dimensions.
The get-go paragraph of the Crisford-Santos newspaper says:
...In higher dimensions, at that spot is abundant numerical evidence that this is possible, thus that this version of the WCCC does non handgrip [2–6]. However, inward all of the previous scenarios, 1 starts with an unstable dark hole solution, in addition to it is far from clear whether such a dark hole tin live on formed inward the get-go place. The instance nosotros supply inward this missive of the alphabet is four-dimensional in addition to starts inward the vacuum of the theory.You tin run into that they reminded the reader that lots of evidence has existed that Penrose's conjecture – fifty-fifty the weakened 1 – was incorrect. But the counterexamples required to a greater extent than than iv spacetime dimensions and non-vacuum initial weather that someone could bring argued to live on forbidden past times themselves. Crisford in addition to Santos bring increased the evidence against the validity of the cosmic censorship conjecture past times finding a counterexample inward \(D=4\); in addition to 1 inward which the initial Blue Planet is the vacuum.
So if at that spot is a existent logical propagation of credibility betwixt the Weak Gravity Conjecture in addition to the Cosmic Censorship Conjecture, it goes just inward the reverse administration than Wolchover wrote, namely:
This alliance betwixt the Weak Gravity Conjecture in addition to Cosmic Censorship Conjecture seems to imply that the Weak Gravity Conjecture that is backed past times stronger in addition to less ambiguous torso of positive evidence helps us to conclude that despite the counterexamples, at that spot is a feel or at that spot are situations inward which the embattled conjecture alongside the two, the Cosmic Censorship Conjecture, is valid, assuming inequalities that are guaranteed past times the consistency of a quantum theory of gravity.You run into that it's substantially dissimilar from the materials that Wolchover wrote.
Also, yous may sentiment the Cosmic Censorship Conjecture every bit a personal property of Roger Penrose. You may inquire him the next question:
By the cosmic censorship conjecture(s), do yous hateful that the naked singularities are avoided inward full general theories inward which Einstein's full general relativity is coupled to other fields, or are they avoided but when yous impose inequalities that tin solely live on guaranteed if 1 insists that the physical theory is a role of string theory?Guess what Penrose would answer. He has unsuccessfully attempted to dismiss string theory every bit "fashion" thus of course of pedagogy he would tell that his conjecture shouldn't depend on string theory. But with this Definition of (any) cosmic censorship conjecture, it's but wrong. This is what Crisford in addition to Santos bring shown. So the claim that this conjecture of Penrose's is to a greater extent than established than ours is but self-evident rubbish.
At the end, all these things are thus obvious in addition to yous ofttimes ask to read but the get-go paragraph of each relevant newspaper to larn these things straight. However, the pop media all the same tend to write lots of things that are but upside downward or otherwise completely wrong. Needless to say, piece I bring mentioned Lidice, Poles are to a greater extent than probable to get upward the rail tape of German-administered villages such every bit Auschwitz in addition to Birkenau.