Loop Quantum Gravity WAR!

A few weeks ago, I released a video about whether string theory’s biggest competitor, Loop Quantum Gravity, might have suffered a fatal blow.

The video sparked a lively debate across YouTube, with creators like Sabine Hossenfelder and Phil Halpern making reaction videos and Carlo Rovelli even reaching out to me personally, asking me to take it down.

Now, I want to clarify the situation and share my perspective on whether Loop Quantum Gravity is truly on its last legs—or if there’s more to the story.

Tune in to the Loop Quantum Gravity War!

Key Takeaways:

00:00 Intro
00:46 My initial video on loop quantum gravity
03:25 Quick recap of my correspondence with Carlo Rovelli
04:20 The problem with string theory and loop quantum gravity
09:08 Reacting to Sabine’s video
12:55 My final thoughts

Additional resources:

➡️ Check out the videos referenced:

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#intotheimpossible #briankeating #loopquantumgravity

[DrBrianKeating]

What is the best candidate for a Theory of Quantum Gravity: String Theory or Loop Quantum Gravity? Or something else?

[williamblake]

People should stop being offended. If someone said your theory sucks, it's up to you either to prove it does not suck or ignore him. But being emotionally offended is not an option.

[l.wayneausbrooks]

Sabine just dropped a blistering diss track

[fishermensfriend]

Sabine just published a video and brought the dilemma of modern physics to the point. I can just repeat what I wrote in her channel: I work with a couple of highly educated, PhD. holding physicists together at Siemens. They all complain about the situation you explain here and they are all pointing to the root cause: It's about the money. People construct fancy theories to pretent progress. Why would else one give them money? It starts at the universities. Modern physics is dead and that will remain till the system gets changed.

[zyzhang]

After watching Sabine’s last and the latest video, I feel whoever disagree with her should try to point out the flaw in her argument, if there is any. As someone who studied a bit physics during undergrad, i feel her argument is pretty clean and conclusive.

[Suggsonbass]

As a Brit I would like to contribute some of my own expertise : "bollocks" are spherical objects usually seen in pairs that orbit one another in a kind of nebula-like sac that is gravitationally locked to the pillar of creation.

[takanara]

Sabine just put out a video about this, lol. Pretty much owns everyone.

[theonetruemorty]

Sabine just summed it up nicely, "sick of hearing it."

[gibijobi]

why the background incredibly annoying and distracting

[melissablick]

I'm not a physicist, but an applied mathematician, which should make my bias obvious. Remember going to lots of talks on this topic during my PhD and postdoc. Even back then, I always thought how on earth all these labs pull in funding without even having a plan for verifiable results. My personal opinion is that creating new math is like creating art. It can be beautiful and elegant, and has value. But with limited funding, I'd rather see resources being put towards more practical endeavours.

[maha-madpedo-gayphukumber]

I have a theory it is called "gravity loop quantum string field" to satisfy both parties.

[willardsteele]

As a scientist but not a physicist, I tend to lean Team Sabine. I tend to be skeptical of the claims of theoretical physicists now. I am old and have heard too many promises. By the way, could you invite Gregory Chaitain. He has make comments about academia and the progress of physics you might or might not like.

[JamaicaWhiteMan]

Sabine represents and presents sensible realism and we're very lucky to have her. It's hardly surprising a lot of supposed physicists obsessed with modern versions of Ptolemy's epicycles would rather she keep her mouth shut.

[floatingblaze]

I don't understand this talk about "having a monopoly is bad". Having untestable/unfalsifiable theories is bad. Having multiple contested theories all of which ignore mathematical inconsistencies or experimental evidence is worse. Having a single theory which can be tested and proven is the most desirable outcome, and by definition that's a monopoly; or as I would call it scientific consensus.

[Thomas-gk]

Haha, thanks for your politeness in this video Dr. Keating, that´s truly how a scientific debate should be. I´m in "team Sabine" and look forward a new episode with her in your show. All the best.

[metaflea]

Why do you have to play a close to sub auditory repetitive tonal sound track during your talk. I do not need to be hipnotized into a somnolent state to remain engaged with the material you are presenting. Please amend your sound tack or eleminate it altogether.

[claudio-roma]

I almost always find categorical statements dubious. For those who are curious, more than ten years ago (2002), Rovelli and Speziale argued that LQG does not necessarily imply violation of Lorentz invariance in the paper:

Carlo Rovelli, Simone Speziale, Reconcile Planck-scale discreteness and the Lorentz-Fitzgerald contraction, Physical Review D 67, 064019 (2003) DOI: 10.1103/PhysRevD.67.064019

In short:
1. The minimum length is not a fixed property of space-time, but a minimum value of a quantum observable. This means that there is no fixed “grid” in space-time, but rather a set of possible discrete values ​​that can be observed.
2. The eigenvalues ​​of observables, such as area, remain unchanged under Lorentz transformations. A moving observer would see the same spectrum of discrete values, with the same minimum area.
3. What changes with the Lorentz transformation is the probability distribution of observing one of these discrete values. This means that the probability of measuring a certain area may change, but the possible measurable values ​​remain the same.

[duggydo]

I for one am glad there is finally some discussion on actual experimental results. Hopefully we are having similar discussions about string theory soon.

[nukerock]

I did watch Sabine Hossenfelder's emphatic appeal regarding whether we should continue to think of / fix linear LQG. I do have sympathy for her pragmatic approach, and the risk of unfairly distorting the balance of research investment.

[montybannerman]

There is a strong smell of personal vested interest and the sunk cost fallacy emanating from those who get their bucks and tickets to conferences from LQG.