Vacuum

Absence of matter

Introduction

A vacuum is a space devoid of matter. The word stems from the Latin term 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.

Historical Development

The concept of vacuum has been central to many scientific advancements. The development of the vacuum pump in the 17th century by Otto von Guericke was a significant milestone. This device allowed for the creation of a vacuum by removing air from a sealed container.

A historical vacuum pump

Early Experiments

In the 17th century, Evangelista Torricelli created the first laboratory vacuum using a barometer. This experiment demonstrated that air had weight and could exert pressure. The

Diagram of a barometer, an early vacuum device

illustrates the basic principle of Torricelli's barometer.

Applications of Vacuum

Vacuum technology has numerous applications in science and industry. It is essential in the production of semiconductors, the operation of electron microscopes, and the creation of incandescent light bulbs.

An incandescent light bulb, which operates in a vacuum

Vacuum Tubes

Vacuum tubes were crucial in the development of early electronics. They control the flow of electricity in a high vacuum between electrodes to which an electric potential difference has been applied. The

A Crookes tube, an early experimental vacuum tube

shows an example of an early vacuum tube used in experiments.

Vacuum in Space

Space is often considered a near-perfect vacuum, although it is not completely devoid of matter. The magnetosphere of Earth, for example, is influenced by the vacuum conditions in space.

Diagram of the magnetosphere, which is influenced by vacuum conditions in space

Measurement of Vacuum

The measurement of vacuum is crucial for many scientific and industrial processes. Instruments such as the McLeod gauge are used to measure low pressures in a vacuum.

A McLeod gauge, used to measure vacuum pressure

Quantum Vacuum

In quantum field theory, the vacuum state is the quantum state with the lowest possible energy. Generally, it contains no physical particles. The concept of vacuum fluctuations arises from the uncertainty principle, which allows for the temporary appearance of particle-antiparticle pairs.

File:Vacuum fluctuations revealed through spontaneous parametric down-conversion.ogv

Vacuum Pumps

Vacuum pumps are devices that remove gas molecules from a sealed volume to leave behind a partial vacuum. They are essential in many industrial and scientific applications.

Diagram of a vacuum pump

Related Pages

• Vacuum pump
• Vacuum tube
• Quantum vacuum
• Barometer
• Magnetosphere