TY - JOUR
T1 - Quintessence, cosmic coincidence, and the cosmological constant
AU - Zlatev, Ivaylo
AU - Wang, Limin
AU - Steinhardt, Paul J.
PY - 1999
Y1 - 1999
N2 - Recent observations suggest that a large fraction of the energy density of the Universe has negative pressure. One explanation is vacuum energy density; another is quintessence in the form of a scalar field slowly evolving down a potential. In either case, a key problem is to explain why the energy density nearly coincides with the matter density today. The densities decrease at different rates as the Universe expands, so coincidence today appears to require that their ratio be set to a specific, infinitesimal value in the early Universe. In this paper, we introduce the notion of a “tracker field,” a form of quintessence, and show how it may explain the coincidence, adding new motivation for the quintessence scenario.
AB - Recent observations suggest that a large fraction of the energy density of the Universe has negative pressure. One explanation is vacuum energy density; another is quintessence in the form of a scalar field slowly evolving down a potential. In either case, a key problem is to explain why the energy density nearly coincides with the matter density today. The densities decrease at different rates as the Universe expands, so coincidence today appears to require that their ratio be set to a specific, infinitesimal value in the early Universe. In this paper, we introduce the notion of a “tracker field,” a form of quintessence, and show how it may explain the coincidence, adding new motivation for the quintessence scenario.
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U2 - 10.1103/PhysRevLett.82.896
DO - 10.1103/PhysRevLett.82.896
M3 - Article
AN - SCOPUS:0001544612
SN - 0031-9007
VL - 82
SP - 896
EP - 899
JO - Physical review letters
JF - Physical review letters
IS - 5
ER -