Ultraviolet

Ultraviolet (UV) light is an electromagnetic radiation with a wavelength from 400 nm (750 THz) to 10 nm (30 PHz), shorter than that of visible light but longer than X-rays. Though usually invisible, under some conditions children and young adults can see ultraviolet down to wavelengths of about 310 nm, and people with aphakia (missing lens) can also see some UV wavelengths. Near-UV is visible to some insects and birds.

UV radiation is present in sunlight, and also produced by electric arcs and specialized lights such as mercury-vapor lamps, tanning lamps, and black lights. Although lacking the energy to ionize atoms, long-wavelength ultraviolet radiation can cause chemical reactions, and causes many substances to glow or fluoresce. Consequently, biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules.

Suntan, freckling and sunburn are familiar effects of over-exposure, along with higher risk of skin cancer. Living things on dry land would be severely damaged by ultraviolet radiation from the sun if most of it were not filtered out by the Earth's atmosphere, particularly the ozone layer. More-energetic, shorter-wavelength "extreme" UV below 121 nm ionizes air so strongly that it is absorbed before it reaches the ground. Ultraviolet is also responsible for the formation of bone-strengthening vitamin D in most land vertebrates, including humans. The UV spectrum thus has effects both beneficial and harmful to human health.

Vacuum

Vacuum is space void of matter. The word stems from the Latin adjective vacuus for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often discuss ideal test results that would occur in a perfect vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is lower than atmospheric pressure. The Latin term in vacuo is used to describe an object as being in what would otherwise be a vacuum.

The quality of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%. Much higher-quality vacuums are possible. Ultra-high vacuum chambers, common in chemistry, physics, and engineering, operate below one trillionth (10⁻¹²) of atmospheric pressure (100 nPa), and can reach around 100 particles/cm³.Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average. According to modern understanding, even if all matter could be removed from a volume, it would still not be "empty" due to vacuum fluctuations, dark energy, transiting gamma rays, cosmic rays, neutrinos, and other phenomena in quantum physics. In the electromagnetism in the 19th century, vacuum was thought to be filled with a medium called aether. In modern particle physics, the vacuum state is considered the ground state of matter.

Vacuum (disambiguation)

Vacuum is the absence of matter.

Vacuum may also refer to:

Vacuum (band)

Vacuum is the name of a Swedish pop band. The members are Mattias Lindblom and Anders Wollbeck. They also work as song writers and producers under the same name. As songwriters and producers Wollbeck and Lindblom have worked with artists such as Tarja Turunen, Tina Arena, Garou, Monrose, TVXQ, Keisha Buchanan, f(x) and The Canadian Tenors. Wollbeck and Lindblom are signed to Universal Music Publishing world wide.

History

Vacuum was formed in 1996 by Anders Wollbeck, Alexander Bard and Mattias Lindblom. Their first single I Breathe was a big hit in large parts of Europe. At that time Marina Schiptjenko was part of the group. After the second album Bard left the group. Vacuum then released the single Starting Where The Story Ended. Schiptjenko left the group shortly after. Wollbeck and Lindblom wrote and produced, in 2004, Vacuum's critically acclaimed album Your Whole Life Is Leading Up To This, marking a new direction for the band. At that point Wollbeck and Lindblom had started writing and producing for other artists as well. Vacuum then released the singles Six Billion Voices in 2006 and Walk On The Sun in 2007. In 2008 Wollbeck and Lindblom started a collaboration with Austrian pianist Michael Zlanabitnig. It resulted in the release of Know By Now and My Friend Misery. The latter being a duet with Marcella Detroit known for her success with Shakespears Sister. In 2009 they released The Ocean. Another single written in collaboration with Zlanabitnig. Vacuum is currently working on new material. The band enjoys a huge fan following. On June 4, 2011, Vacuum released the song Black Angels.