Physics | The Canadian Encyclopedia

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  • Article


    Viscosity is the ability of a flowing liquid or gas to develop internal shear stresses that resist flow. In air, viscous forces are generally small in comparison with inertia forces, a condition which leads to flow instability and turbulence.

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  • Article


    Astronomy is the science that studies the sun, the solar system, the remote stars, distant galaxies and all other detectable bodies in the universe. Its major subdisciplines include astrophysics, the closely related field of spectroscopy and cosmology. Astronomy is often regarded as the oldest science. For more than 5,000 years, motions in the sky have been used to predict events such as the annual flood of the Nile River. During the era of modern exploration, astronomy had practical applications in navigation, surveying and timekeeping. Modern astronomy, however, is more concerned with the physical and chemical nature of matter beyond Earth, where conditions of temperature, pressure and gravitational and magnetic fields allow astronomers to observe matter under extremes unattainable in terrestrial laboratories. Astronomy is also closely related to physics,  chemistry, mathematics, geology, engineering and computer science.

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  • Article


    Astrophysicists use many branches of physics: nuclear physics to study power-generation in stars; atomic physics to understand the spectra of stars and gaseous nebulae; and gas laws and magnetic theory to probe starspots and flares on star surfaces.

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  • Article

    Black Hole

    A black hole is an object in outer space whose the gravitational field is so strong that no matter or light can escape. Astronomers believe such regions can form from the collapse of massive stars. Researchers at Canadian institutions have contributed to theories supporting the existence of black holes.

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  • Article

    Bridge Disasters in Canada

    There have been several fatal bridge disasters over the course of Canada’s history, some during construction, others after a bridge was in use for some time. The following is a chronological account of the worst of these tragic events, including Canada’s most fatal bridge disaster, the 1907 collapse of the Quebec Bridge. (See also Highway Disasters; Railway Disasters.)

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  • Article

    Canada and the Manhattan Project

    Canada helped develop the world’s first nuclear reactors and nuclear arms. During the Second World War, Canada participated in British research to create an atomic weapon. In 1943, the British nuclear weapons program merged with its American equivalent, the Manhattan Project. Canada’s main contribution was the Montreal Laboratory, which later became the Chalk River Laboratory. (See Nuclear Research Establishments). This Allied war effort produced the atomic bombs dropped on the Japanese cities of Hiroshima and Nagasaki in 1945. It also led to the development of Canada’s nuclear energy industry. Click here for definitions of key terms used in this article.

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  • Macleans

    Canada's Astronomers Doing Stellar Research

    CANADIANS ARE masters of the universe. Just look at the numbers. Sure, the U.S. leads the world in spending on space research, laying out roughly US$7 per American each year, while Britain, France and Germany budget between US$4 and US$5 for every citizen.This article was originally published in Maclean's Magazine on September 5, 2005

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  • Article

    Challenger Expedition

    The Challenger expedition, the first worldwide oceanographic expedition, voyaged 127 663 km in the Atlantic, Southern, Indian and Pacific oceans between December 1872 and May 1876.

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  • Article

    Collapse of the Peace River Bridge

    ​The spectacular suspension bridge across the Peace River south of Fort St. John, British Columbia, was opened in the summer of 1943, replacing a ferry crossing on the Alaska Highway.

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  • Macleans

    Comet Hale-Bopp Puts on a Show

    Thomas Bopp is a big, broad-shouldered man with a deep voice, a quiet demeanor and a look on his face that suggests he would like to get this experience over quickly. The 47-year-old amateur astronomer from Phoenix, Ariz.This article was originally published in Maclean's Magazine on March 10, 1997

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  • Article


    How the world began is a question as old as the human race. It was not before the 20th century, however, that the evolution and large-scale structure of the universe emerged as a well-defined problem of interest to science.

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  • Article

    David Dunlap Observatory

    David Dunlap Observatory, see OBSERVATORY.

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  • Macleans

    Exploring Mars

    Driver required to operate robotic rover from 190 million kilometres away. Must be able to negotiate vehicle across rock-strewn martian terrain using commands that take 11 minutes to arrive. Experience with computer games an asset.This article was originally published in Maclean's Magazine on July 21, 1997

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  • Article


    Serious attempts to estimate the size of the galaxy began in the 19th century.

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  • Article


    Gravity, the fundamental physical property of attraction between all bodies, is here considered mainly as it relates to the study of the Earth.

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