منابع مشابه
A small but nonzero cosmological constant
Recent astrophysical observations seem to indicate that the cosmological constant is small but nonzero and positive. The old cosmological constant problem asks why it is so small; we must now ask, in addition, why it is nonzero (and is in the range found by recent observations), and why it is positive. In this essay, we try to kill these three metaphorical birds with one stone. That stone is th...
متن کاملWhy do we observe a small but nonzero cosmological constant?
The current observations seem to suggest that the universe has a positive cosmological constant of the order of H 2 0 while the most natural value for the cosmological constant will be L−2 P , where LP = (Gh̄/c3)1/2 is the Planck length. This reduction of the cosmological constant from L−2 P to L −2 P (LPH0) 2 may be interpreted as due to the ability of quantum microstructure of spacetime to rea...
متن کاملHow natural is a small but nonzero cosmological constant?
Based on our previous attempt, we propose a better way to understand a small but nonzero cosmological constant, as indicated by a number of recent observational studies. We re-examine the assumptions of our model of two scalar elds, trying to explain the basic mechanism resulting in a series of mini-in ations occuring nearly periodically with respect to ln t with t the cosmic time. We also disc...
متن کاملA two-scalar model for a small but nonzero cosmological constant
We revisit a model of the two-scalar system proposed previously for understanding a small but nonzero cosmological constant. The model provides solutions of the scalar-fields energy ρs which behaves truly constant for a limited time interval rather than in the way of trackeror scalingtype variations. This causes a mini-inflation, as indicated by recent observations. As another novel feature, ρs...
متن کاملFat Euclidean Gravity with Small Cosmological Constant
The cosmological constant problem is usually considered an inevitable feature of any effective theory capturing well-tested gravitational and matter physics, without regard to the details of short-distance gravitational couplings. In this paper, a subtle effective description avoiding the problem is presented in a first quantized language, consistent with experiments and the Equivalence Princip...
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ژورنال
عنوان ژورنال: International Journal of Modern Physics D
سال: 2001
ISSN: 0218-2718,1793-6594
DOI: 10.1142/s0218271801000627