Explosions In 2007

An explosion is a rapid expansion in volume associated with an extreme outward release of energy, usually with the generation of high temperatures and release of high-pressure gases. Supersonic explosions created by high explosives are known as detonations and travel through shock waves. Subsonic explosions are created by low explosives through a slower combustion process known as deflagration.

Causes

Explosions can occur in nature due to a large influx of energy. Most natural explosions arise from volcanic or stellar processes of various sorts. Explosive volcanic eruptions occur when magma rises from below, it has very dissolved gas in it. The reduction of pressure as the magma rises and causes the gas to bubble out of solution, resulting in a rapid increase in volume. Explosions also occur as a result of impact events and in phenomena such as hydrothermal explosions (also due to volcanic processes). Explosions can also occur outside of Earth in the universe in events such as supernovae. Explosions frequently occur during bushfires in eucalyptus forests where the volatile oils in the tree tops suddenly combust.

Astronomical

Among the largest known explosions in the universe are supernovae, which occur after the end of life of some types of stars. Solar flares are an example of a common, much less energetic explosion on the Sun, and presumably on most other stars as well. The energy source for solar flare activity comes from the tangling of magnetic field lines resulting from the rotation of the Sun's conductive plasma. Another type of large astronomical explosion occurs when a very large meteoroid or an asteroid impacts the surface of another object, such as a planet. For example, the Tunguska event of 1908 is believed to have resulted from a meteor air burst.

Black hole mergers, likely involving binary black hole systems, are capable of radiating many solar masses of energy into the universe in a fraction of a second, in the form of a gravitational wave. This is capable of transmitting ordinary energy and destructive forces to nearby objects, but in the vastness of space, nearby objects are usually rare. The gravitational wave observed on 21 May 2019, known as GW190521, produced a merger signal of about 100 ms duration, during which time is it estimated to have radiated away 9 solar masses in the form of gravitational energy.

Chemical

The most common artificial explosives are chemical explosives, usually involving a rapid and violent oxidation reaction that produces large amounts of hot gas. Gunpowder was the first explosive to be invented and put to use. Other notable early developments in chemical explosive technology were Frederick Augustus Abel's development of nitrocellulose in 1865 and Alfred Nobel's invention of dynamite in 1866. Chemical explosions (both intentional and accidental) are often initiated by an electric spark or flame in the presence of oxygen. Accidental explosions may occur in fuel tanks, rocket engines, etc.

Electrical and magnetic

A high current electrical fault can create an 'electrical explosion' by forming high energy electrical arc which rapidly vaporizes metal and insulation material. This arc flash hazard is a danger to people working on energized switchgear. Excessive magnetic pressure within an ultra-strong electromagnet can cause a ''magnetic explosion''.

Mechanical and vapor

Strictly a physical process, as opposed to chemical or nuclear, e.g., the bursting of a sealed or partially sealed container under internal pressure is often referred to as an explosion. Examples include an overheated boiler or a simple tin can of beans tossed into a fire.

Boiling liquid expanding vapor explosions are one type of mechanical explosion that can occur when a vessel containing a pressurized liquid is ruptured, causing a rapid increase in volume as the liquid evaporates. Note that the contents of the container may cause a subsequent chemical explosion, the effects of which can be dramatically more serious, such as a