[ZZipZZipe]

arXiv Find: Reasons Not to Believe in the String Theory Landscape

by Sean Carroll
Tom Banks has long been skeptical of the popular picture of the string theory landscape — the idea that there is some extremely large (10500 or more) number of phases of string theory, representing different ways to compactify the extra dimensions, and that all these phases are dynamically connected to each other, possibly by cosmological transitions during eternal inflation. Tom’s reasons aren’t of the curmudgeonly you-kids-get-off-my-lawn sort, but arise from his views about how quantum gravity works. (He thinks different cosmological boundary conditions represent truly different quantum theories, not just different regions of one big spacetime.) Well worth considering, if only because it’s too easy to run off in the direction of conventional wisdom when you’re far away from the realm of experimental testing.





The String Landscape is a fantasy. We actually have a plausible landscape of minimally supersymmetric $AdS_4$ solutions of supergravity modified by an exponential superpotential. None of these solutions is accessible to world sheet perturbation theory. If they exist as models of quantum gravity, they are defined by conformal field theories, and each is an independent quantum system, which makes no transitions to any of the others. This landscape has nothing to do with CDL tunneling or eternal inflation.



A proper understanding of CDL transitions in QFT on a fixed background dS space, shows that the EI picture of this system is not justified within the approximation of low energy effective field theory. The cutoff independent physics, defined by the Euclidean functional integral over the 4-sphere admits only a finite number of instantons. Plausible extensions of these ideas to a quantum theory of gravity obeying the holographic principle explain all of the actual facts about CDL transitions in dS space, and lead to a picture radically different from eternal inflation.



Theories of Eternal Inflation (EI) have to rely too heavily on the anthropic principle to be consistent with experiment. Given the vast array of effective low energy field theories that could be produced by the conventional picture of the string landscape one is forced to conclude that the most numerous anthropically allowed theories will disagree with experiment violently.



http://blogs.discovermagazine.com/co...ory-landscape/




>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>


The Top 10^{500} Reasons Not to Believe in the Landscape

T. Banks
(Submitted on 28 Aug 2012)
The String Landscape is a fantasy. We actually have a plausible landscape of minimally supersymmetric $AdS_4$ solutions of supergravity modified by an exponential superpotential. None of these solutions is accessible to world sheet perturbation theory. If they exist as models of quantum gravity, they are defined by conformal field theories, and each is an independent quantum system, which makes no transitions to any of the others. This landscape has nothing to do with CDL tunneling or eternal inflation.
A proper understanding of CDL transitions in QFT on a fixed background dS space, shows that the EI picture of this system is not justified within the approximation of low energy effective field theory. The cutoff independent physics, defined by the Euclidean functional integral over the 4-sphere admits only a finite number of instantons. Plausible extensions of these ideas to a quantum theory of gravity obeying the holographic principle explain all of the actual facts about CDL transitions in dS space, and lead to a picture radically different from eternal inflation.
Theories of Eternal Inflation (EI) have to rely too heavily on the anthropic principle to be consistent with experiment. Given the vast array of effective low energy field theories that could be produced by the conventional picture of the string landscape one is forced to conclude that the most numerous anthropically allowed theories will disagree with experiment violently.




http://arxiv.org/abs/1208.5715

[BartRonalds]

> Reasons Not to Believe in the String Theory Landscape

It's a brilliant idea, and I had a soft spot in my heart for it, until it was wiped out recently by the non-existence of supersymmetry.

> Theories of Eternal Inflation (EI) have to rely too heavily on the anthropic principle to be consistent with experiment.

Absolutely not, quite the reverse. The string theory landscape is literally the only way that an anthropically consistent universe could have evolved without invoking the anthropic principle.

In addition, they totally miss the fact that the string theory landscape does not rely on Eternal Inflation.

Or to put it another way, this article looks like a piece of polemic junk.