Observational Bounds on Cosmic Doomsday
نویسندگان
چکیده
منابع مشابه
Possible Anthropic Support for a Decaying Universe: a Cosmic Doomsday Argument *
I have suggested that one possible solution of the Boltzmann brain problem is that the universe is decaying at an astronomical rate, making it likely to decay within 20 billion years. A problem with this suggestion is that it seems to require unnatural fine tuning in the decay mechanism that would not be explained anthropically. Here it is pointed out that if a spacetime version of volume avera...
متن کاملForecasting cosmic doomsday from CMB-LSS cross-correlations
A broad class of dark energy models, which have been proposed in attempts at solving the cosmological constant problems, predict a late time variation of the equation of state with redshift. The variation occurs as a scalar field picks up speed on its way to negative values of the potential. The negative potential energy eventually turns the expansion into contraction and the local universe und...
متن کاملLimits on the detectability of cosmic topology in hyperbolic universes
We reexamine the possibility of the detection of the cosmic topology in nearly flat hyperbolic Friedmann-Lemâıtre-Robertson-Walker (FLRW) universes by using patterns repetition. We update and extend our recent results in two important ways: by employing recent observational constraints on the cosmological density parameters as well as the recent mathematical results concerning small hyperbolic ...
متن کاملObservational bounds on the cosmic radiation density
We consider the inference of the cosmic radiation density, traditionally parameterised as the effective number of neutrino species Neff , from precision cosmological data. Paying particular attention to systematic effects, notably scaledependent biasing in the galaxy power spectrum, we find no evidence for a significant deviation of Neff from the standard value of N 0 eff = 3.046 in any combina...
متن کاملTime variation of the fine structure constant in the early universe and the Bekenstein model
Aims. We calculate bounds on the variation of the fine structure constant at the time of primordial nucleosynthesis and at the time of neutral hydrogen formation. We use these bounds and other bounds from the late universe to test Bekenstein model. Methods. We modify the Kawano code, CAMB and CosmoMC in order to include the possible variation of the fine structure constant. We use observational...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2003