Very early in my study of physics, Weyl became one of my gods. I use the word “god” rather than, say, “outstanding teacher” for the ways of gods are mysterious, inscrutable, and beyond the comprehension of ordinary mortals. 188 more words

## Tags » Mathematical Physics

#### Dynamical symmetries and observational constraints in scalar field cosmology [CL]

http://arxiv.org/abs/1410.4930

We propose to use dynamical symmetries of the field equations, in order to classify the dark energy models in the context of scalar field (quintessence or phantom) FLRW cosmologies. 169 more words

#### Lattice Universe: examples and problems [CL]

http://arxiv.org/abs/1410.3909

We consider lattice Universes with spatial topologies $T\times T\times T$, $\; T\times T\times R\; $ and $\; T\times R\times R$. In the Newtonian limit of General Relativity, we solve the Poisson equation for the gravitational potential in the enumerated models. 142 more words

#### Why are sound waves longitudinal?

“Give me some example for waves in nature! “

“Sound is a wave.. Light is a wave.. Of course we see water waves.. “

Thats the usual answer we think about when asked that question. 541 more words

#### General Relativity and Gravitation: A Centennial Perspective [CL]

http://arxiv.org/abs/1409.5823

To commemorate the 100th anniversary of general relativity, the International Society on General Relativity and Gravitation (ISGRG) commissioned a Centennial Volume, edited by the authors of this article. 116 more words

#### A New Solution of Einstein Vacuum Field Equations [CL]

http://arxiv.org/abs/1409.3758

A new solution of Einstein’s vacuum field equations is discovered which appears as a generalization of the well-known Ozsvath-Schucking solution and explains its source of curvature which has otherwise remained hidden. 84 more words

#### Friedmann's Equations in All Dimensions and Chebyshev's Theorem [CEA]

http://arxiv.org/abs/1409.3352

This short but systematic work demonstrates a link between Chebyshev’s theorem and the explicit integration in cosmological time $t$ and conformal time $\eta$ of the Friedmann equations in all dimensions and with an arbitrary cosmological constant $\Lambda$. 191 more words