BUBBLE encyclopedia topics

bubble chamber, device for detecting charged particles and other radiation by means of tracks of bubbles left in a chamber filled with liquid hydrogen or other liquefied gas. It was invented in 1952 by Donald Glaser. The bubble chamber consists essentially of a sealed chamber to be filled with a liquefied gas and constructed so that the pressure inside can be reduced quickly. The liquid is originally at a temperature just below its boiling point. When the pressure is reduced, the boiling point becomes lowered so that it is less than the temperature of the liquid, leaving the liquid superheated. When a charged particle passes through this superheated liquid, it leaves a trail of tiny gas bubbles that can be illuminated and photographed. The track of a charged particle can be used to identify the particle and to analyze complex events in which it may be involved. If a magnetic field is present, the tracks of the particles will be curved, positively charged particles curving in one direction and negatively charged particles curving in the opposite direction. The degree of curvature depends on the mass, speed, and charge of the particle. Neutral particles can be detected indirectly by applying various conservation laws to the events recorded in the bubble chamber or by observing their decay into pairs of oppositely charged particles. The bubble chamber is particularly useful for studying high-energy particles that would pass through a cloud chamber too quickly to leave a detailed enough track but which pass more slowly through the bubble chamber because of the greater density of the liquid. Liquid hydrogen and helium are commonly used in bubble chambers, with special equipment needed to maintain these gases in their liquid state (see low-temperature physics). For experiments requiring very dense liquids, a variety of organic compounds may be used. See elementary particles; particle accelerator; spark chamber.

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Licensed from Columbia University Press

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South Sea Bubble

South Sea Bubble, popular name in England for the speculation in the South Sea Company, which failed disastrously in 1720. The company was formed in 1711 by Robert Harley, who needed allies to carry through the peace negotiations to end the War of the Spanish Succession. Holders of £9 million worth of government bonds were allowed to exchange their bonds for stock (with 6% interest) in the new company, which was given a monopoly of British trade with the islands of the South Seas and South America. The monopoly was based on the expectation of securing extensive trading concessions from Spain in the peace treaty. These concessions barely materialized, however, so that the company had a very shaky commercial basis. Nonetheless, it was active financially, and in 1720 it proposed that it should assume responsibility for the entire national debt, again offering its own stock in exchange for government bonds, a transaction on which it expected to make a considerable profit. The government accepted this proposal, and the result was an incredible wave of speculation, which drove the price of the company's stock from £1281/2 in Jan., 1720, to £1,000 in August. Many dishonest and imprudent speculative ventures sprang up in imitation. In Sept., 1720, the bubble burst. Banks failed when they could not collect loans on inflated stock, prices of stock fell, thousands were ruined (including many members of the government), and fraud in the South Sea Company was exposed. Robert Walpole became first lord of the treasury and chancellor of the exchequer and started a series of measures to restore the credit of the company and to reorganize it. The bursting of the bubble, which coincided with the similar collapse of the Mississippi Scheme in France, ended the prevalent belief that prosperity could be achieved through unlimited expansion of credit. Legislation was enacted that forbade unincorporated joint stock enterprise.

See studies by L. S. Benjamin (1921, repr. 1968), J. Carswell (1960), and V. S. Cowles (1960).

The Columbia Electronic Encyclopedia Copyright © 2004.
Licensed from Columbia University Press

bubble chamber

Subatomic-particle detector that uses a superheated liquid which boils into tiny bubbles of vapour along the tracks of the particles. As charged particles move through the liquid, they knock electrons from the atoms of the liquid, creating ions. If the liquid is close to its boiling point, the first bubbles form around these ions. The observable tracks can be photographed and analyzed to measure the behaviour of the charged particles. Developed in 1952 by Donald Glaser, the bubble chamber proved very useful in the 1960s and '70s for the study of high-energy nuclear and particle physics.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.

South Sea Bubble

(1720) Speculation mania that caused financial ruin for many British investors. Parliament's acceptance of a proposal by the South Sea Co. to take over the British national debt resulted in an immediate rise in its stock. After soaring from 12812 to over 1,000 in nine months, the bubble of overvalued stock burst and the price per share dropped to 124, dragging other stocks down and leaving many investors ruined. An inquiry by the House of Commons found collusion by several government ministers.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.