Earthquakes radiate waves with periods of tenths of seconds to several minutes. Rocks behave like elastic solids at these frequencies. Elastic solids allow a variety of wave types and this makes the ground motion after an earthquake or explosion (called an event) quite complex. There are two basic types of elastic wave: one involving compression and rarefaction of the elastic material in the direction of propagation of the wave, and one involving no compression but shear of the elastic material perpendicular to its direction of propagation. These are called P and S waves respectively, for primary and secondary since the P wave travels fastest and arrives first.

The propagation of elastic waves in a homogeneous solid is governed by a hyperbolic system of three linear second-order partial differential equations with constant coefficients. When the solid is also isotropic, the form of these equations is well known and provides the foundation of the conventional theory of elasticity (Love 1944). The explicit solution of the initial value, or Cauchy, problem for the isotropic case was found by Poisson, and in a different way by Stokes (1883). If the initial disturbance is sharp and concentrated, the resulting disturbance at a field point will consist of an initial sharp pressure wave, a continuous wave for a certain period, and a final sharp shear wave. The disturbance then ceases.

Now, the velocity of wave propagation can be seen, without the aid of any mathematical analysis, to depend on the elasticity of the medium and its density; for we can see that if a medium is highly elastic the disturbance would be propagated at a great speed.

Itchingham Lofte had caused explosions before. There had, in truth, been many bangs, flashes, and smells coming from his bedroom in the past. His multi-stained carpet and pockmarked walls were a testament to that. But there had been nothing like this explosion—it made even more of an imact than the small earthquake that had rippled under Cornwall a few months before.

The SDT proposes that the causes of revolutions and major rebellions are... similar to processes that cause earthquakes. In both... it is useful to distinguish "pressures" (structural conditions, which build up slowly) from "triggers" (sudden releasing events, which immediately precede a social or geological eruption).

After a large earthquake the earth "rings" like a bell; this motion can be observed on sensitive instruments up to a month after a large event. These oscillations have specific frequencies which are properties of the whole earth and which can be measured very accurately indeed. The lowest frequency oscillation has a period of about one hour. Any combination of seismic waves can be represented as an equivalent combination of normal modes. In practice the mode representation is most useful at low frequency — for seismic waves above about 40 s — since at higher frequencies the number of modes becomes prohibitively large.

After demonstrating the practicability of this method of transmission, the thought naturally occurred to me to use the earth as a conductor, thus dispensing with all wires. Whatever electricity may be, it is a fact that it behaves like an incompressible fluid, and the earth may be looked upon as an immense reservoir of electricity, which, I thought, could be disturbed effectively by a properly designed electrical machine. Accordingly, my next efforts were directed toward perfecting a special apparatus which would be highly effective in creating a disturbance of electricity in the earth.

Matthew Choptuik, a postdoctoral student at the University of Texas, carried out a simulation on a supercomputer that he hoped would reveal new, unexpected features of the laws of physics; and he hit the jackpot. What he simulated was the implosion of a gravitational wave.47 When the imploding wave was weak, it imploded and then disbursed. When it was strong, the wave imploded and formed a black hole. When its strength was very precisely “tuned” to an intermediate strength, the wave created a sort of boiling in the shapes of space and time. The boiling produced outgoing gravitational waves with shorter and shorter wavelengths. It also left behind, at the end, an infinitesimally tiny naked singularity

It would be interesting to use high temperatures - in the billions, which develop during atomic bomb explosions, for conducting synthetic reactions (for example, the formation of helium from hydrogen), which are the source of energy of stars and which could raise the energy liberated during the explosion of basic matter (uranium, bismuth, lead) even higher.

Matthew Choptuik, a postdoctoral student at the University of Texas, carried out a simulation on a supercomputer that he hoped would reveal new, unexpected features of the laws of physics; and he hit the jackpot. What he simulated was the implosion of a gravitational wave.47 When the imploding wave was weak, it imploded and then disbursed. When it was strong, the wave imploded and formed a black hole. When its strength was very precisely “tuned” to an intermediate strength, the wave created a sort of boiling in the shapes of space and time. The boiling produced outgoing gravitational waves with shorter and shorter wavelengths. It also left behind, at the end, an infinitesimally tiny naked singularity (Figure 26.7). Fig. 26.6. Our bet about naked singularities. Fig. 26.7. Left: Matthew Choptuik. Middle: An imploding gravitational wave. Right: The boiling produced by the wave, and the naked singularity at the center of the magnifying glass. Now, such a singularity can never occur in nature. The required tuning is not a natural thing. But an exceedingly advanced civilization could produce such a singularity artificially by precisely tuning a wave’s implosion, and then could try to extract the laws of quantum gravity from the singularity’s behavior.

An earthquake in one department created tidal waves in others.

These transverse vibrations are not produced (as in the older theories of light) by simple atomic vibrations, but their pitch depends on the shape of the hollow space which the molecule forms in the ether, just as Hertzian waves are not caused by vibrations of the ponderable matter of the brass balls, the form of which only determines the pitch.

When somebody provokes your anger, the only reason you get angry is because you’re holding on to how you think something is supposed to be. You’re denying how it is. Then you see it’s the expectations of your own mind that are creating your own hell. When you get frustrated because something isn’t the way you thought it would be, examine the way you thought, not just the thing that frustrates you. You’ll see that a lot of your emotional suffering is created by your models of how you think the universe should be and your inability to allow it to be as it is.

What scientists have only recently discovered is that the more familiar earthquakes, those that are easily measured while in progress and instantaneous in their destruction, are often preceded by longer, slow-moving, catastrophic disruptions rumbling twenty miles or more beneath us, too deep to be felt and too quiet to be measured for most of human history.