String Theorists on Loop Quantum Gravity ( ft. Edward Witten)

From Strings 2021ICTP-SAIFR Strings 2021 - June 27 - Ask a String Theorist

String Theorists on being asked about alternative theories for quantum gravity

[greggballanger]

Edward Witten, you should write a book for people.

[mlguy]

“The only game in town” drops mic and walks away.

[professorboltzmann]

0:31 that voice always cracks me up: imagine Lord Voldemort became a physicist and had a crack on the mysterious Quantum Gravity ... now I wonder who the "Harry Potter" of the story is?!

[rogierbrussee]

"it may look like we are a cult, but I have seriously looked at Tai Chi to see if it is an alternative to Yoga, but no, all I can say, it is not an alternative to Yoga, Yoga is the only game in town"

[goddamn]

What about quantizing the EM field to get photons? LQG is quantizing continuum space time to get quanta of space time..

[isedairi]

I don't know which is worst, physics or economics, when dealing with alternatives to their accepted frameworks.

[quantumofspace]

A hybrid of quantum space, this is the theory of ether + theory of quantum strings = quanta of membranes (such as rosebuds). It will turn out 1) the quantum Universe from chaos. 2) Universe from quantum fractals. 3) The visible universe is on the border between fractal and chaos.

[ngogol]

“We may look like a church and talk like a church but don't let that fool you. We really are a church.” (free adaptation of a groucho marx phrase)

[lucaspierce]

All other Approaches to QG are just Add ons & Extensions based on Previous Works in it's Quantization! I totally Agree! Many of these so called Alternatives were Inspired by or are Based on String Theory including Shape Dynamics which I see as Much more Promising than LQG!.

[vaidphysics]

The funny thing is Loop Quantum Gravity makes concrete predictions whereas string theory has not one prediction after 60 years of being "the only game in town". Ultimately Nature decides who is right and not scientist's egos.

[bastamtajik]

Witten better reconsider his answer by remembering the lack of evidence for SUSY and the exclusion of MSSM by neutron EDM, as well as the instability of string vacuum in de Sitter space and the highly ambitious premises of strings in comparison to LQG( Several higher dimensions, SUSY etc.). QFT came into existence out of philosophical question about the second law of thermodynamics and Maxwell's demon paradox by Planck and its following 5 papers as a discourse between Planck and Boltzmann + Einstein's wisdom in calculating the vacuum energy fluctuations and sub volume Entropy of the black body. String theory even correct in the distant future never followed such Philo-scientific evolutionary path and is relying on pure mathematical grounds without human's involvement in the theory at any level. I wish we could learn from Einstein that he was led to GR by philosophy and not by mathematical beauty as the string community proclaims. I'm wondering how the hell one can ignore the foundations of QM and try to mix GR with QM! There's not even 10 active groups working on such deep questions that can definitely change our views about QM and gravity while thousands of people try to make an open-ended version of string theory just more mathematically rigorous! Posterity will contempt us for our ignorance and arrogance.

[nowonda]

I'm a total layman, but if you phrase it like that ("is LQG an alternative to ST?"), the answer is obviously no, because they both have different goals, although they overlap on some domain. It's like asking "is wine an alternative to water?" Also, for a theory that's been worked on and developed by hundreds of brilliant minds for a few decades now but which does not have a reasonable end product in sight, it would be better for everyone (us laymen included) if string theorists and adepts of LQG would not behave like highschool girls when talking about each other...

[r.williamcomm]

“Survey says….” No is don’t like it. OK then we’ll just take your word for it that it’s bunk. There is no spoon. 😂

[pepperpepperandbayleaf]

The most cult like behavior ever from scientists.

[Plx]

String Theory is neither background-independent nor diffeomorphism invariant and needs not detected supersymmetrie ! If it is the only „Game in Town“, the „Town“ seems to be very small, more a village !

[radinelaj]

, sorry, you didn't find out any thing, you just maximized the problem, but didn't found the point ( the essence) you just extend the problem, you just carried the problem to another ( smaller) size , you should find the edge between particles and strings, the connection between them, ( in that connection there is another edge, in that edge there is another edge..and so on...deeper and deeper on the edge there is another edge and deeper there is another edge and deeper there is another edge...and so on, how many edges are?! Where did this process ends ?! this is the point, hope you understand

[JTNugget]

Ed Witten must explain quantum gravity’s failure.

[ntf]

I don't like the host's arrogance and ego.

[neutronstar]

These guys are smiling as if they had achieved their goal of reconciling GR and quantum mechanics. The sad and cold reality (that they will never recognise) is that they simply failed... and String Theory might be regarded in a couple of decades as the greatest failure / waste of time in modern physics considering the amount of human resources, brain power, money put in it. This clip contains the core reason of why this happened: arrogance !!! David gross' face when he's talking about LQG says it all.