After Heaviside’s attempts to generalize Maxwell’s equations, Heaviside came to the conclusion that electromagnetic waves were not to be found as longitudinal waves in “free space” or homogeneous media. But Maxwell’s equations do lead to the appearance of longitudinal waves under some circumstances, for example, in plasma waves or guided waves. Basically distinct from the “free-space” waves, such as those studied by Hertz in his UHF experiments, are Zenneck waves. The longitudinal modes of a resonant cavity are the particular standing wave patterns formed by waves confined in a cavity. The longitudinal modes correspond to those wavelengths of the wave which are reinforced by constructive interference after many reflections from the cavity’s reflecting surfaces. Recently, Haifeng Wang et al. proposed a method that can generate a longitudinal electromagnetic (light) wave in free space, and this wave can propagate without divergence for a few wavelengths.
Among the ringed gas giant planet Saturn's amazing collection of 62 diverse, bizarre, and beautiful moons and moonlets, sometimes one of them just seems to stand out in the crowd. Such a moon is little Methone. Looking like a shiny white egg in Space, and composed of very lightweight fluffy stuff, Methone is less dense than any other known moon or asteroid in our Solar System. In March 2013, astronomers announced at the 44th Lunar and Planetary Science Conference held in the Woodlands, Texas, that this strange little 5-kilometer-size moon is one of a batch of Space eggs in orbit around Saturn! This important measurement was made using Cassini's INMS instrument, which detects gases with the goal of determining their composition. INMS was designed to sample the upper atmosphere of Saturn's large, smoggy moon Titan. However, after Cassini's surprising discovery of a tall plume if icy spray erupting from cracks on Enceladus in 2005, planetary scientists turned its detectors to that small moon. The Moon in the Birth Chart. The Moon is a very important planet in the Birth Chart as it is from this that we operate from through childhood and thus it becomes our foundation. Although we grow towards our Sun (our own 'mind') in adulthood, the Moon is a 'feeling, reflective' energy that picks up and stores early messages and experiences. Many of our behavioural and emotional problems can be uncovered by examining the role of Moon in the Natal Chart. The Moon informs and represents the way we habitually respond and react throughout life. It denotes our instinctive behaviour and the sign it is in describes its innate quality, whereas the house reflects the environmental influence. Any aspect to the Moon shows how it reacts. If for example it has a connection to Mars, then it may be more assertive in having its needs met. Moon with Venus will emphasise its female or creative quality and Moon in aspect to Mercury may be able to express its feeling in some communicative way..