منابع مشابه
Is Our Universe Brany ?
Brane-world models, which have received a lot of attention during the last few years, are essentially characterized by two basic ideas: • they assume the existence of spatial extra dimensions, in addition to our four space-time dimensions. The higher dimensional spacetime is usually called the “bulk” spacetime; • our accessible Universe is assumed to be a submanifold, called “brane”, embedded i...
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In the 3 century BCE, the Greek mathematician Eratosthenes was able to estimate the Earth’s circumference. He learned that on the summer solstice the Sun at noon was reflected in a deep well in the southern Egyptian city of Syene, which indicated that the Sun was directly overhead at that time. He also knew the Sun was not directly overhead at that time where he lived (Alexandria, in northern E...
متن کاملHow Anisotropic is Our Universe?
Large-scale cosmic microwave background anisotropies in homogeneous, globally anisotropic cosmologies are investigated. We perform a statistical analysis in which the four-year data from the Cosmic Background Explorer satellite is searched for the specific anisotropy patterns predicted by these models and thereby set definitive upper limits on the amount of shear, (σ/H)0 and vorticity, (ω/H)0, ...
متن کاملOn the Stability of Our Universe
We argue that the Robertson-Walker’s Universe is a zero-energy stable one, even though it may possess a rotational state besides expansion.
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Recent observations of Cepheids in the Virgo cluster have bolstered the evidence that supports a Hubble constant in 70−90 km sec−1 Mpc−1 range. This evidence, by and large, probes the expansion of the Universe within 100Mpc. We investigate the possibility that the expansion rate within this region is systematically higher than the true expansion rate due to the presence of a local, large underd...
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ژورنال
عنوان ژورنال: Journal of Aircraft and Spacecraft Technology
سال: 2017
ISSN: 2523-1200
DOI: 10.3844/jastsp.2017.69.79