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ensabah6

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From the point of view of the techniques of (four-dimensional) quantum field theory, and as the numerous and heroic efforts to formulate a consistent quantum gravity theory by some very able minds attests, gravitational quantization was, and is still, the reigning champion for bad behavior. There are problems and frustrations stemming from the fact that the gravitational coupling constant has dimensions involving inverse powers of mass, and as a simple consequence, it is plagued by badly behaved (in the sense of perturbation theory) non-linear and violent self-interactions. Gravity, basically, gravitates, which in turn...gravitates...and so on, (i.e., gravity is itself a source of gravity,...,) thus creating a nightmare at all orders of perturbation theory. Also, gravity couples to all energy equally strongly, as per the equivalence principle, so this makes the notion of ever really "switching-off", "cutting-off" or separating, the gravitational interaction from other interactions ambiguous and impossible since, with gravitation, we are dealing with the very structure of space-time itself.

Suppose one were to introduce as a hypothetical physical principle, the idea of "quantum minimal energy" -- simply put, there is a minimal "quanta" of energy that results in graviton interactions, and below this threshold, there is no graviton interactions. Suppose that one were to conjecture, as a physical principle, the graviton carries too little energy (or for some unknown physical principle, spin-2 particles do not self-interact below a certain threshold)

would this make gravitons perturbation in non-SUSY 4D QFT re-normalizable? While this might seem ad-hoc, if it works, it might be worth researching. Also, there is no technology to explore such incredibly weak effects.

there might not been a need for strings, SUSY, or loops. Just QFT with some additional physical principles, like a cut-off.