He pointed out – in addition to tried to clearly articulate in addition to decorate amongst a novel term – something that all string theorists ever saw. The effective laws of physics that y'all may derive equally long-distance approximations of string theory aren't exactly "any" or "generic" effective plain theories. Effective plain theories let likewise many features that are prohibited inwards string theory. String theory seems to imply roughly extra weather in addition to regularities that couldn't pick out been derived past times effective plain theory itself.
These days, the Weak Gravity Conjecture (WGC), the get-go hep-th preprint of 2006, is in all probability the most well-known illustration of these swampland-like restrictions. Some people fifty-fifty know the term WGC spell they're ignorant nigh the full general concept of the swampland.
But WGC is exactly 1 type of full general predictions that are especial for string theory. Cumrun pointed out that the volume of moduli spaces seems to last finite inwards string theory – spell effective plain theories seemed to let both finite in addition to infinite volumes.
Also, the issue of plain species seems to last finite, similar the ranks in addition to dimensions of approximate groups. And inwards May 2006, Ooguri in addition to Vafa discussed roughly full general but characteristically stringy deportment of the particle spectrum close especial points of the moduli space. The density grows amongst the majority inwards a certainly way. I would add together that the omnipresent "towers of states" inwards string theory pick out to last at that spot because they're the precursors to the exponentially growing towers of dark hole microstates inwards quantum gravity.
Among similar observations, nosotros also divulge the observation that it's hard, to tell the least, to realize "large scale inflation" inside string theory. With canonically normalized kinetic damage for scalar fields, it seems difficult to let an inflaton to motility past times much to a greater extent than than 1 Planck mass. It seemed similar string theory would prefer Guth's one-time inflation over Linde's novel inflation.
In all of this business, the observed extra constraints were commonly figured out past times "experimentally watching" properties of string theory's vacua. But string theory is a consistent theory of quantum gravity in addition to many of us divulge it probable that it's the alone consistent theory of quantum gravity. So these stringy constraints may also last viewed equally hypothetical restrictions that consistency of quantum gravity (a seemingly to a greater extent than full general framework) imposes on effective plain theories that may last incorporated.
More generally, seemingly non-stringy arguments may last constructed to fence that the weather implied past times string theory truly follow from the coherent unification of quantum mechanics in addition to gravity. So far, all clear plenty statements are consistent amongst the supposition that "string theory" in addition to "consistent quantum gravity" are the same creature observed from dissimilar directions.
In the get-go hep-th preprint today,
Emergence in addition to the Swampland ConjecturesBen Heidenreich, Matthew Reece, in addition to Tom Rudelius are trying to convey roughly fellowship to these seemingly unrelated, chaotic observations nigh the "extra constraints" imposed past times string theory. They derive the rich tower of low-cal states from a novel supposition they suggest equally a to a greater extent than key one: the supposition that loop corrections drive both gravity in addition to scalar interactions to the rigid coupling at the same scale (well, this is a classify of a "soft unification" supposition in addition to I volition work that term for their assumption).
With this assumption, the collection of states that instruct low-cal close a betoken of the moduli infinite automatically needs to last a "rich tower of states". The same "soft unification" supposition of theirs also seems to imply that the "large plain inflation" should last prohibited.
These qualitative properties of string theory and/or quantum gravity should last understood increasingly good – including diverse logical relationships betwixt seemingly independent assumptions of this sort. Along amongst roughly progress inwards the data loss paradox in addition to entanglement/glue duality, a crisp novel Definition of string theory or quantum gravity could ultimately emerge inwards forepart of the eyes of mortal whose thinking nigh the matters is simply clever.