| Science_Magazine__Energy_special_issue__1978 Article topics included biomass, photovoltaics, CANDU nuclear reactor technology, and prospects for hydrogen energy. Now in PDF format. (February 10, 1978) |
| Science_Magazine__Energy_special_issue__1974 Many articles on energy technology and the energy crisis: technical, social, political and economic aspects. Now in PDF format. (April 19, 1974) |
| MagCAD MagCAD is a simple low-cost software tool for calculation of spatial distribution of the magnetic field created by permanent magnets and electric coils at presence of nonlinear ferromagnetic materials |
| Analytical_Reference_Materials_International Source for instrument calibration standards, CRMs for the oil, coal, and metals industries. |
| Antares_Analytical_-_Baird_Spectrometer_Specialists International service, parts, supplies and support for Baird spectrometers by Baird trained engineers. Distributor of GNR and Angstrom spectrometers for metals and oil analysis. |
| Applied_Analysis Manufacturer of in-process diode array for UV, Vis, NIR spectrophotometers. |
| Applied_Computing_Technology,_Inc_ Total spectroscopic instrumentation solutions. [JAVA required.] |
| Applied_Spectroscopy Supplies high-speed measuring technology for the photodiode array spectroscopy, film thickness measurement, and PVD plasma emission monitoring. |
| Aquila_Instruments_Ltd Aquila manufactures the nkd spectrophotometer for thin film analysis, including refractive index, absorption coefficient and coating thickness measurement. similar to ellipsometers. Spectroscopy for t |
| Avian_Technologies,_LLC Maker of spectrometric calibration accessories (UV, VIS and IR). |
| Burgener_Research_International Producer of Teflon Burgener Parallel Path Nebulizers such as Mira Mist, a nonsalting, nonplugging micro nebulizer for ICP, ICP/MS spectrometers. Supplier of sample preparation equipment and supplies. |
| Camspec Maker of single and dual beam UV spectrometers and related accessories. |
| Cascade_Science Offers carbon, hydrogen, oxygen and nitrogen elemental analysis equipment. Uses flash pyrolysis and spectroscopy for detection of elements. |
| Centre_Optics Produces a variety of optical components, including thin film interference filters, in a range of bands, particularly for analytical determination of gaseous substance concentrations. Based in Kiev, U |
| Climax_Technology Power supplies for Deuterium UV lamp. |
| Control_Development,_Inc_ Manufacturers of optical spectrographs, detector heads and fiber optic accessories. |
| CPI_International Instrument supplies, standards and lab accessories for spectroscopy and metal digestion apparatus. |
| CRAIC_Technologies Manufactures a UV-visible-NIR range microspectrophotometer and a Questioned Document System. These are used for non-destructive analysis of microscopic samples. |
| CuvetteShop_com Offers cells and cuvettes for spectrophotometers and fluorometers. |
| DeltaNu Raman spectrometers for academic use. Includes historical tutorial, applications, instrument specification and contacts at their division of CC Technology, Inc, Laramie, Wyoming. |
| Designs_and_Prototypes,_Ltd_ Designing and building very small, low power, rugged FTIR spectrometers for use in portable, airborne and commercial applications. |
| Detector_Technology_Europe_ Engineers and manufactures channel electron multipliers for high performance and maximum reliability. Retrofit or new design. Used for Mass Spectroscopy. |
| Edinburgh_Instruments_Ltd Manufacturers of steady state and time resolved fluorescence spectrometers using single photon counting and time correlated single photon counting techniques. Laser flash photolysis also available. |
| Elvatech_Ltd_ Designs and manufactures spectrometry, data collection and analytical software. Company also makes laser markers. Located in Kiev, Ukraine. |
| Engineer\'s_Office_for_Applied_Spectroscopy Offers high-speed gauges for photodiode array spectroscopy. |
| FTIR NICODOM - FTIR and FTNIR spectrometers , spectral libraries FT-IR and FT-NIR, infrared spectroscopy, silicon windows |
| Getspec Modular fibre optic spectrometer for UV/VIS, NIR and Raman applications, laboratory equipment, accessories |
| Getspec_com Offers modular fibre optic spectrometer and accessories for UV/VIS, NIR, Raman and Fluorescence applications |
| Goffin_Meyvis_Analytical_and_Medical_Systems_ Instrumentation for clinical chemistry, hematology, analytical laboratories. ICP, XRF, AA, spectrometers. |
| ICP_glassware Precision glassblowing of Colorado manufactures replacement glassware for ICP and ICP-MS instrumentation. Offers torches, nebulizers, injectors, spray chambers, and other associated items. |
| Infrared_Analysis,_Inc_ Specializes in the measurement of gases. Manufacturer of long path gas cells and remote monitoring systems. 270 compound quantitative IR database with automatic gas analysis software. |
| In-spec Manufacturer of color spectrum and optical standards and calibration for spectrometers. |
| Ion_Optics Has pulsed infrared sources that are used in non-dispersive infrared gas sensing equipment. |
| ISS_Fluorescence_and_Biomedical_Instrumentation Manufacturer of fluorescence instrumentation, spectrofluorometers, photon counting spectrofluorometers, fluorescence correlation spectrometers, high pressure cells, and oximeters. |
| J__A__Woollam_Co_,_Inc_ Spectroscopic ellipsometers for thin film and bulk materials chacterization. Measures thin film thickness and material optical constants. In-situ and ex-situ, spectral ranges from Vacuum UV to Far IR. |
| JASCO\'s_Analytical_Instrumentation HPLC, Circular Dichroism, Polarimetry, SNOM, Raman, FTIR, UV-Visible Fluorescence and Polarimetry instrumentation |
| JETI JETI Technische Instrumente GmbH offers various products for spectral measurement, ranging from components like read-out electronics and OEM spectrometers to systems for different applications. |
| Jobin_Yvon_Ltd Manufacturer of gratings, monochromators, Raman spectrometers, spectroscopic ellipsometers, spectrofluorometers, synchrotron beam line monochromators and wavelength multiplexers. |
| JY_Horiba Detectors for ICP, Raman, fluorescence as well as gratings, monochromators, detectors, and plasma processing equipment. Includes contacts for worldwide suppliers and research and development labs in E |
| Kaiser_Optical_Systems,_Inc_ Manufacturer of diode laser and CCD-based spectrometers, analyzers, microscopes, holographic filters, spectrographs and instruments for process, analytical and research, Raman spectroscopy application |
Understanding General Relativity too Table of Content The Principles of General Relativity Background The equivalence principle Gravity as Curvature Gravitational Redshift and Time Dilation Tidal Forces GR and Newtonian gravity Verifications of the GR Theory Einstein's Field Equation Curved Space Geometry External and Internal Curvature Tangent Vectors and Tangent Spaces Tensors Parallel Transport Riemann Curvature Tensor The Metric Ricci Tensor, Weyl tensor and Ricci Scalar The Geometric Meaning of Curvature Tensors The Field Equation and More Einstein Tensor The Stress-Energy Tensor The Equation The Point Mass Solution The Interior Solution Black Holes A Model of the Universe Understanding General Relativity too By Rafi Moor 2005 The purpose of this article is to introduce General Relativity to people with basic knowledge of mathematics and physics. Familiarity with the basics of Special Relativity is also required. Talking about General Relativity without getting into higher mathematics is not an easy mission. Much of the theory of GR deals with advanced mathematical issues. One can't cover the main topics of GR without getting into some mathematical issues. I have divided the article to three parts so that the reader can decide how deep he wants to dive into the subject. The first part introduces the principles of GR without any mathematics at all. The second part discusses curved space geometry without getting into the detailed mathematics of it. The third part describes Einstein's field equation and some consequences of it. 
