منابع مشابه
Quintessence and the cosmological constant
The idea of quintessence originates from an attempt to understand the smallness of the “cosmological constant” or dark energy in terms of the large age of the universe [1]. As a characteristic consequence, the amount of dark energy may be of the same order of magnitude as radiation or dark matter during a long period of the cosmological history, including the present epoch. Today, the inhomogen...
متن کاملEffective cosmological “constant” and quintessence
In this paper we present exactly solved extended quintessence models; furthermore, through a dynamical effective Q-cosmological ”constant”, we recover some of the Λ decaying cases found in the literature. Finally we introduce a sort of complementarity between the Q-dominated or Λdominated expansions of the Universe. e-mail addresses: [email protected] [email protected]
متن کاملThe cosmological constant problem and quintessence
I briefly review the cosmological constant problem and the issue of dark energy (or quintessence). Within the framework of quantum field theory, the vacuum expectation value of the energy momentum tensor formally diverges as k. A cutoff at the Planck or electroweak scale leads to a cosmological constant which is, respectively, 10 or 10 times larger than the observed value, Λ/8πG ≃ 10 GeV. The a...
متن کاملConformal fixed point, cosmological constant, and quintessence.
We connect a possible solution for the "cosmological constant problem" to the existence of a (postulated) conformal fixed point in a fundamental theory. The resulting cosmology leads to quintessence, where the present acceleration of the expansion of the universe is linked to a crossover in the flow of coupling constants.
متن کاملSmooth Energy: Cosmological Constant or Quintessence?
For a flat universe presently dominated by smooth energy, either cosmological constant (LCDM) or quintessence (QCDM), we calculate the asymptotic collapsed mass fraction as function of the present ratio of smooth energy to matter energy R0. Identifying the normalized collapsed fraction as a conditional probability for habitable galaxies, we observe that the observed present ratio R0 ∼ 2 is like...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Nuclear Physics B - Proceedings Supplements
سال: 2003
ISSN: 0920-5632
DOI: 10.1016/s0920-5632(03)02077-2