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.

Introduction

Introduction, The Introduction, Intro, or The Intro may refer to:

Intro (R&B group)

Intro is an American R&B trio from Brooklyn, New York City, New York. The trio consisted of members Jeff Sanders, Clinton "Buddy" Wike and lead singer/songwriter Kenny Greene. Intro released two albums (for Atlantic Records): 1993's Intro and their second album, 1995's New Life. The group had a string of US hits in the 1990s. The hits included the singles "Let Me Be The One", the Stevie Wonder cover "Ribbon in the Sky", "Funny How Time Flies" and their highest charting hit, "Come Inside".

Intro's Kenny Greene died from complications of AIDS in 2001. Intro recently emerged as a quintet consisting of Clinton "Buddy" Wike, Jeff Sanders, Ramon Adams and Eric Pruitt. Adams departed in 2014, with the group back down to its lineup as a trio. They are currently recording a new album to be released in 2015. The group released a new single in 2013 called "I Didn't Sleep With Her" and a new single "Lucky" in October 2014.

Discography

Albums

Singles

References

Introduction (music)

In music, the introduction is a passage or section which opens a movement or a separate piece, preceding the theme or lyrics. In popular music this is often abbreviated as intro. The introduction establishes melodic, harmonic, and/or rhythmic material related to the main body of a piece.

Introductions may consist of an ostinato that is used in the following music, an important chord or progression that establishes the tonality and groove for the following music, or they may be important but disguised or out-of-context motivic or thematic material. As such the introduction may be the first statement of primary or other important material, may be related to but different from the primary or other important material, or may bear little relation to any other material.

A common introduction to a rubato ballad is a dominant seventh chord with fermata, Play  an introduction that works for many songs is the last four or eight measures of the song, Play  while a common introduction to the twelve-bar blues is a single chorus. Play