6 research outputs found
The information paradox and the locality bound
Hawking's argument for information loss in black hole evaporation rests on
the assumption of independent Hilbert spaces for the interior and exterior of a
black hole. We argue that such independence cannot be established without
incorporating strong gravitational effects that undermine locality and
invalidate the use of quantum field theory in a semiclassical background
geometry. These considerations should also play a role in a deeper
understanding of horizon complementarity.Comment: 21 pages, harvmac; v2-3. minor corrections, references adde
Sinks in the Landscape, Boltzmann Brains, and the Cosmological Constant Problem
This paper extends the recent investigation of the string theory landscape in
hep-th/0605266, where it was found that the decay rate of dS vacua to a
collapsing space with a negative vacuum energy can be quite large. The parts of
space that experience a decay to a collapsing space, or to a Minkowski vacuum,
never return back to dS space. The channels of irreversible vacuum decay serve
as sinks for the probability flow. The existence of such sinks is a
distinguishing feature of the string theory landscape. We describe relations
between several different probability measures for eternal inflation taking
into account the existence of the sinks. The local (comoving) description of
the inflationary multiverse suffers from the so-called Boltzmann brain (BB)
problem unless the probability of the decay to the sinks is sufficiently large.
We show that some versions of the global (volume-weighted) description do not
have this problem even if one ignores the existence of the sinks. We argue that
if the number of different vacua in the landscape is large enough, the
anthropic solution of the cosmological constant problem in the string landscape
scenario should be valid for a broad class of the probability measures which
solve the BB problem. If this is correct, the solution of the cosmological
constant problem may be essentially measure-independent. Finally, we describe a
simplified approach to the calculations of anthropic probabilities in the
landscape, which is less ambitious but also less ambiguous than other methods.Comment: 42 pages, 5 figures, the paper is substantially extended, a section
on the cosmological constant is addeed; the version published in JCA
Cosmological Measures without Volume Weighting
Many cosmologists (myself included) have advocated volume weighting for the
cosmological measure problem, weighting spatial hypersurfaces by their volume.
However, this often leads to the Boltzmann brain problem, that almost all
observations would be by momentary Boltzmann brains that arise very briefly as
quantum fluctuations in the late universe when it has expanded to a huge size,
so that our observations (too ordered for Boltzmann brains) would be highly
atypical and unlikely. Here it is suggested that volume weighting may be a
mistake. Volume averaging is advocated as an alternative. One consequence may
be a loss of the argument that eternal inflation gives a nonzero probability
that our universe now has infinite volume.Comment: 15 pages, LaTeX, added references for constant-H hypersurfaces and
also an idea for minimal-flux hypersurface