Abstract
In canonical quantum gravity, the formal functional integral includes an
integration over the local conformal factor, and we propose to perform the
functional integral over this factor before doing any of the other functional
integrals. By construction, the resulting effective theory would be expected to
be conformally invariant and therefore finite. However, also the conformal
integral itself diverges, and therefore the actual situation is more delicate.
The effects of a renormalization counter term are considered, including the
associated problem of unitarity violation, such as a Landau-like ghost. Adding
(massive or massless) matter fields does not change the picture; to confirm
this, detailed calculations were necessary, and they are presented. Some
alternative ideas are offered, including a more daring speculation, which is
that no counter term should be allowed for at all. This has far-reaching and
important consequences, which we discuss. A surprising picture emerges of
quantized elementary particles interacting with a gravitational field that is
"partly classical". This approach was inspired by a search towards the
reconciliation of Hawking radiation with unitarity and locality, and it offers
basic new insights there.
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