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PrefaceIt is possible that physics in the early 21St century is near the possibility of experimental tests of quantum gravity. This is an expository on the subject, where phenomenology and experimental prospects play a crucial part. With the exception of the final three chapters of this book, much of the discussion here may become empirically relevant within a couple of decades. By this it is hoped that the topics will become at best "old physics" in the light of subsequent developments within a few decades into the 21St century.This book is written to become a part of a process that leads to an empirical understanding of quantum gravity, as well as the development of a possible final theory of physics. This final theory may at best be a theory that describes the universe up to the limits of what is understandable. Here there are proposed quantum gravity experiments which could be performed in the next one or two decades. These may help to initiate the study of quantum gravity as a really empirical science.Despite the incredible difference in scale between the Planck scale and the scale of current experimental physics, it has to be recognized that there are similar precedents in the past. The ancient world had no means to examine the atomic structure, but there were considerable speculations on the nature of atoms stemming from Democritus. The Epicurean cosmos framed the cosmos on three fundamental principles: materialism, mechanism, and atomism. Epicurus thought the universe as an infinitude of space and events were played out according to matter within a void. Epicurus upholds Democritus theory that all matter is composed of indestructible atoms, with eternal properties that can neither be created or destroyed. However, whereas Democritus thought the number of atomic sizes and shapes as infinite, Epicurus argued that their number, while large, is nevertheless finite. Lucretius wrote that atoms could be any size, where he argued that the slow motion of oil through a sieve indicated the largeness of the atoms that constituted oil. Democritus claimed atoms move in straight lines in all directions and always in accordance with the iron laws of "necessity." In the first century B.C.E. Lucretius This is a remarkable insight that was most completely codified by Einstein in 1905.This suggests that insights of today can potentially lead to unexpected empirical results. Given the current age of rapid technological development, barring any sort of upheaval similar t o the end of the ancient world and the so called "dark ages," the lag time between insight and measurement should be much shorter.The intention is t o connect various theories and ideas about quantum gravity and quantum fluctuations. Many of the current theoretical constructs of this physics are discussed in connections with the main theoretical point advanced here: quantum gravity requires a quantum uncertainty principle more general than obtained in current quantum physics. Quantum gravity is also discussed in the light of possible experimental tests tha...

It is shown that if the Lorentz condition is discarded, the Maxwell–Heaviside field equations become the Lehnert equations, indicating the presence of charge density and current density in the vacuum. The Lehnert equations are a subset of the O(3) Yang–Mills field equations. Charge and current density in the vacuum are defined straightforwardly in terms of the vector potential and scalar potential, and are conceptually similar to Maxwell's displacement current, which also occurs in the classical vacuum. A demonstration is made of the existence of a time dependent classical vacuum polarization which appears if the Lorentz condition is discarded. Vacuum charge and current appear phenomenologically in the Lehnert equations but fundamentally in the O(3) Yang–Mills theory of classical electrodynamics. The latter also allows for the possibility of the existence of vacuum topological magnetic charge density and topological magnetic current density. Both O(3) and Lehnert equations are superior to the Maxwell–Heaviside equations in being able to describe phenomena not amenable to the latter. In theory, devices can be made to extract the energy associated with vacuum charge and current.

Lightning spectra in the 850‐ to 1400‐nm near‐infrared region have been recorded with 200‐ to 300‐ms time resolution using a slitless spectrometer with a lead sulfide detector. Except for the wire portion of triggered discharge channels, rocket triggered and natural return stroke spectra are very similar. The following neutral atomic nitrogen (NI) and oxygen (OI) multiplet emissions have been identified (the wavelength, in nanometers, of the brightest line in each group is shown in parentheses): NI(2) (821.6), OI(4) (844.6), NI(1) (868.0), NI(15) (906.1), OI(8) (926.6), NI(7) (939.3), NI(19) (986.2), NI(18) (1011.3), NI(28) (1053.9), and NI(36) (1246.8). Continuum emissions with peak intensities at least an order of magnitude less than the strongest line emissions were detected. A laboratory arc simulation of a return stroke discharge produced a near‐IR spectrum containing all the features emitted by lightning. Additional NI radiation peaks at 1131.4 nm (NI(17)) and 1358.1 nm on the arc spectra overlapped water vapor absorption bands and were not visible on lightning spectra recorded at 2.2‐km range. A time‐averaged lightning channel temperature of about 16,000°K was calculated from the ratio of relative intensities of the NI(1) and NI(18) multiplets.