renormalize some theories
why can we renormalize some theories but others not?..in fact what wo7uld happen if we apply renormalization group method,or Feynmann,s renormalization program to quatnum gravity (non renormalizable theories).
I also found that http://arXiv.org/abs/hepth/9507067 they claim to have solved the problem of renormalization..is that true?. 
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Theories for which an infinite number of parameters would have to be renormalized are called unrenormalizable, and they can't be developed with present methods as finite theories. Gravity turns out to be unrenormalizable. Every time you try to renormalize one parameter, another crops up. 
and could the divergences in a nonrenormalizable theory be removed by using Renormalization group method and its equations?....another question for any lagrangian where i could find information about renormalization group method.

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So, you can say that gravity is a catastrophy, or you can say that it is a small remnant of another theory at high energies. cheers, Patrick. 
And just to add to what Patrick said, renormalization group methods are not instead of renormalization, they are in addition to it. For example RG methods don't renormalize QCD but they do show that confinement follows from renormalization.

There is something about nonrenormalizable theories what bothers me. In fact, I'm not sure whether, if you restrict yourself to a given order, say, second order perturbation, can you do loop diagrams, or are you screwed any way ?
I mean, I don't know if you get already an infinitude of counterterms at a given order, or whether at each order, you have to add more, but a finite number each time, of counter terms. cheers, Patrick. 
I think you only need to add more terms at each order. From the one theory that I'm aware of ('naive' IVB theory of the weak interaction), the divergences get worse order by order (ie they diverge as x^{kn}, where n is the order is k is constant).

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