Here some update from an expert: https://arxiv.org/pdf/2002.05703.pdf
From the conclusions: "At present, it is not possible to derive a sufficiently complete effective theory from full loop quantum gravity, and even if this were possible, it is not clear whether loop quantum gravity itself is...
The end of science in the sense of trying to find an explanation. This is about the scientific method. Essentially she claims that an observed fine tuning does not need to have an explanation, any observed numerical quantity is a good as any other one, so stop here, cancel experiments, it is all...
Hossenfelders crusade against particle physics is getting more ridiculous every day. In essence she promotes the end of science. It is like as if a remote forrest was discovered where all the trees have the same height up to one nanometer. If people say, this is unnatural, there must be some...
This problem has many facets, even without perturbation theory and the Planck scale. That's why I highlighted in my previous post a related problem, which is non-perturbative in nature, namely the QCD phase transition (one may also consider the weak symmetry breaking scale). While the hierarchy...
You wrote a very good comment on her board. She obviously lacks the understanding of the subject, but nevertheless makes strong claims (even hinting that she considers 1000's of other physicists as being wrong - that is always a very bad sign).
One may also add the following perspective to...
Hi Urs,
thanks fot your answer. Still I am confused: the only instance where I could vaguely understand a doubling to linearize the T-Duality G < Sp(200) is to double the number of coordinates of the moduli space (roughly, there is a symplectic polarization so that half of the periods (minus...
Hi Urs,
I wasn't that sophisticated, rather than just naive. Upon glancing over the paper you cited I found I understand
next to nothing, at least without studying it for hours..
So to clarify the basic setup, we have the following scalars:
a) 3 complex scalars which are the coordinates...
What is a matter for Sugra philosophy, is the fixation on tori. Which is fine for some applications, but one should not expect to draw more general conclusions from this geometry. Try to make T-duality for CY's manifest and you see what I mean...
This is a classic example which shows that importing too much supergravity philosophy into string theory can do more harm than good. Supergravity people usually consider tori and at most spheres as backgrounds. And indeed, this doubled field theory works essentially only for tori but not for...
Naive non-renormalisability is just one of many problems that arise if you try to quantise gravity. There are clashes between unitarity and locality at a deeper level. They manfest themselves for example in black holes. Naive approaches such as UV fixed points do not shed any light on these...
Sure, there is the usual renormalization taking place. But there is no "calculation" of the CC in particle field theory, because the first quantum correction is infinite anyway. So you can attribute any number to it, whatever you like, since it is undetermined in field theory (unless if you...
Sure it does. But there are several contributions to the CC, the vacuum energy of the Higgs field at the minimum of its potential is just one. There is no meaning in particle field theory of the absolute value, so a constant term can always be added. In gravity, that term matters however. A...
Time exists independently of any matter fields, purely in GR. In fact there is no deep relation between GR and the Higgs mechanism. It is not true that the mass of "all" matter is due to the latter; in fact, 95% of the observed mass is not generated by the Higgs mechanism, but rather by the...