Geophysics Starter

Geophysics Gravimetry
 

Geophysical fluid
dynamics

Radioactivity

Geomagnetism

Geothermal Physics

Mineral physics

Seismology

Magnetosphere

Geophysics
Electromagnetics

Size, form and
structure of the Earth

Plate Tectonics
 

Lunar Recession
 

Geophysics is the physics of the Earth and its surrounding environment in space. Geophysics is the application of physics to the Earth and other planetary bodies.

Radioactivity

Radioactivity is the phenomenon where by an unstable atomic nucleus emits ionizing radiation causing the nucleus to loses energy and rest mass.

In alpha decay the nucleus ejects an alpha particle.
An alpha particle is a helium atomic nucleus consisting of 2 protons and 2 neutrons.
The process reduces the atomic number of atom by 2 changing the element.

In negative Beta decay a neutron emits a Beta particle and an electron anti-neutrino to become a proton.
Beta particles are actually negatively charged electrons.
This process increases the atomic number of the nucleus by one.

Accelerated Nuclear Decay is the process by which nuclear decay proceeds at a faster rate than normal. Now small amounts of accelerated nuclear decay have been observed in Bata-decay under some circumstances. Now accelerated alpha decay has never directly been observed. However evidence exists for accelerated Alpha-decay in the retention of radiogenic helium by zircon crystals. Accelerated  Substantial accelerated alpha decay would produce a lot of heat but theoretical solutions to this problem do exist. Accelerated alpha decay would drastically reduce radiometric ages and measured helium diffusion rates in zircon crystals are a perfect match to a model showing accelerated alpha decay about six thousand years ago.

Seismology

Seismology is the science of earthquakes and the way elastic waves  propagatethrough the Earth and other planetary bodies. On Earth these elastic waves are often the result of Earth quakes which are a result sudden releases of energy in the Earth's crust creating seismic waves. The strength of an Earth quake is measured by a base 10 logarithmic scale called the Richter scale.

There are three main types of seismic waves:
Body waves which travel through the Earth.
Surface waves which travel through the Earth’s crust.
Normal modes that ring the Earth like a bell.

Seismic waves have been used to map the interior of the Earth.
This works because the waves travel at different speeds as the density and composition change.

Lunar Recession

One aspect of Geophysics that gets little attention for its degree of importance is the recession of moon. That’s right moon is slowly getting farther away and slowing the Earth’s rotation in the process. It was first discovered following the Apollo moon landings by bouncing laser off reflectors left behind by astronauts. These reflectors were designed to accurately measure the Earth / Moon distance. The results showed that the moon is getting further away at a rate of 1.5 inches or 3.82 cm per year. Furthermore a day is getting longer by 1.7 milliseconds per day per century.

Backwards projection based on the observed slowing of the Earth's rotation 

Backwards projection based on the observed slowing of the Earth's rotation
A backwards projection of the number of days in a year based on forces  acting on Moon and Earth.	This a backwards projection of the distance of the moon based on forces  acting on Moon and Earth

This is a backwards projection of  the observed slowing of the Earth's rotation and lunar recession data. The current data is simply plugged into the laws of physics. The result is that the Moon would have been locked in Geosynchronous orbit around the Earth 1.25 billion years ago. This is far short of the 4.533 billion years commonly given for the age of the Earths suggesting that the Earth-Moon system can not be any where near 4.533 billion years old.

The problem is understood by the proponents of a 4.533 billion year old Earth and several solution have been proposed. The problem is that paleontological data claimed as evidence for longer days in the past does not fit with any possible model that allows 4.533 billion years The ultimate response seems to be that the Earth-Moon system is too complicated to get accurate results form such calculations. This is essentially admitting that the problem can not be solve for an Earth-Moon system that is 4.533 billion years old. Which is exactly what would be the case if the Earth-Moon system were indeed much younger than 4.533 billion years.

Geophysics

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