vacuum
Sign in to savethumb|300x300px|Vacuum pump and bell jar for vacuum experiments, used in science education during the early 20th century, on display in the Schulhistorische Sammlung ('School Historical Museum'), [[Bremerhaven, Germany]]
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A vacuum is a space that is empty of matter, or nearly empty of air and other gases. Scientists and educators have used special equipment like vacuum pumps and bell jars to study vacuums and demonstrate their properties in experiments.
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Article
20 sectionsContents
- Etymology
- Historical understanding
- Classical field theories
- Gravity
- Electromagnetism
- Quantum mechanics <span class="anchor" id="The quantum-mechanical vacuum"></span>
- Outer space
- Measurement
- Relative versus absolute measurement
- Measurements relative to 1 atm
- Measuring instruments
- Uses
- Vacuum-driven machines
- Outgassing
- Pumping and ambient air pressure
- Effects on humans and animals
- Examples
- See also
- References
- External links
thumb|300x300px|Vacuum pump and bell jar for vacuum experiments, used in science education during the early 20th century, on display in the Schulhistorische Sammlung ('School Historical Museum'), [[Bremerhaven, Germany]]
A vacuum (: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective (neuter ) meaning "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 considerably lower than atmospheric pressure. The Latin term in vacuo is used to describe an object that is surrounded by a vacuum.