Energy Distribution of a G\"{o}del-Type Space-Time

We calculate the energy and momentum distributions associated with a G\"{o}del-type space-time, using the well-known energy-momentum complexes of Landau and Lifshitz and M{\o}ller. We show that the definitions of Landau and Lifshitz and M{\o}ller do not furnish a consistent result.Comment: LaTex, no figure

The two sector endogenous growth model: an atlas

In this paper we investigate the underlying structure of the Lucas (1988) endogenous growth model. We derive analytically, the restrictions on the parameter space that are necessary and sufficient for the existence of balanced growth paths and saddle-path stable local dynamics. We demonstrate that in contrast to the original model, with the addition of an external effect and depreciation in the human capital sector, the Lucas model can be made consistent with the high degrees of intertemporal elasticities of substitution increasingly estimated in the empirical literature even if there is a significant degree of increasing returns to scale in the physical production sector of the economy. Finally we demonstrate that for a given baseline rate of steady state growth, with the inclusion of modest degrees of depreciation and external effects to the human capital production process, the model can accommodate the widest possible range of economies including those characterized by low discount factors, high elasticities of intertemporal substitution, increasing returns in the final goods sector, and also both the high rates of population growth and steady state per-capita output growth we observe in many parts of the world today

M{\o}ller Energy-Momentum Complex of a Static Axially Symmetric Vacuum Space-Time

The energy and momentum densities associated with the Weyl metric are calculated using M{\o}ller's energy-momentum complex. These results are compared with the results obtained by using the energy-momentum complexes of Einstein, Landau and Lifshitz, Papapetrou and Bergmann. We show that the aforementioned different prescriptions and that of M{\o}ller do not give the same energy density, while give the same momentum density.Comment: LATEX, 9 pages, no figures, an improved version, references added, corrections [Admin note: substantial overlap with gr-qc/0403097, gr-qc/0404108 , gr-qc/0303009 , hep-th/0311050

The impact of immigrant dynasties on wage inequality

I construct a set of dynamic macroeconomic models to analyze the effect of unskilled immigration on wage inequality. The immigrants or their descendants do not remain unskilled–over time they may approach or exceed the general level of educational attainment. In the baseline model, the economy’s capital supply is determined endogenously by the savings behavior of infinite-lived dynasties, and I also consider models in which the supply of capital is perfectly elastic, or exogenously determined. I derive a simple formula that determines the time discounted value of the skill premium enjoyed by college-educated workers following a change in the rate of immigration for unskilled workers, or a change in the degree or rate at which unskilled immigrants become skilled. I compare the calculations of the skill premiums to data from the U.S. Current Population Survey to determine the long-run effect of different immigrant groups on wage inequality in the United States

M{\o}ller's Energy in the Kantowski-Sachs Space-time

We present a counter example to paper \cite{P71} and show that the result obtained is correct for a class of metric but not general. We calculate the total energy of the Kantowski-Sachs space-time by using the energy-momentum definitions of M{\o}ller in the theory of general relativity and the tetrad theory of gravity.Comment: 7 pages and no figure

On the Singularities of Reissner-Nordstr\"{o}m Space-Time

It is shown that if two Reissner-Nordstr\"{o}m space-times, both with the same mass m and charge e, glued together in the singularities, then the light ray in black hole of the first space-time can go continuously through the singularity into black hole of the second. The behavior of tidal forces near the Reissner-Nordstr\"{o}m space-time singularity is examined by considering what happens between two particles falling freely towards the singularity.Comment: Latex, 4 figures, 11 page