Vanishing electrical resistance in condensed matter introduced the phenomena of superconductivity. More recently, the discovery of quantum Hall effects (QHE) stemmed from studies of zero-resistance states at low temperatures, T, and high magnetic fields, B, in the 2-Dimensional Electron System (2DES). Quantum Hall effect and superconductivity have shown that observations of vanishing resistance in unusual settings can be a harbinger of new physics. It turns that the GaAs/AlGaAs 2DES can also exhibit vanishing diagonal resistance, without Hall resistance quantization, at low T and low B when the specimen is excited by electromagnetic waves in the microwave and terahertz parts of spectrum, and that these zero-resistance-states occur about B = [4/(4j+1)] Bf with j=1,2,3…, where Bf= 2p f m*/e, m*is the electron mass, e is electron charge, and f is the EM-wave frequency. Here, we report recent developments in the study of such photo-excited phenomena at low temperatures, in the large filling factor limit, in this ultra high mobility 2DES. 1) R. G. Mani et al., Nature 420, 646 (2002) संक्षिप्त जीवनी / Brief Biography : Ramesh Mani is an Indian-born American physicist who obtained his BS, MS, and Ph.D. at the University of Maryland, College Park, MD in the USA. After the time at the University of Maryland, he worked as a scientist at the Max-Planck-Institute for Solid State Physics in Stuttgart, Germany. He returned to the USA with a position at the University of California at Santa Barbara (UCSB), California. After a brief stay at UCSB, he moved to Harvard University as a senior research associate in Dean Venky Narayanamurti's group. In 2006, he moved to Georgia State University where he is now Professor of Physics & Astronomy. At Georgia State University, he has set up a large laboratory for materials preparation, device fabrication by lithography, and low temperature, high magnetic field magneto-transport studies of low dimensional systems based on GaAs/AlGaAs heterostructures, graphene, and other modern atomic layer 2D systems.