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| A COSMIC REPORT.
Timothy Ferris sums up the universe in "The Whole Shebang." |
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Questions asked
in this forum:Was Einstein wrong? What was the location of the Big Bang ? What was the universe like before the Big Bang? If the universe is expanding, is gravity weakening? What is the universe expanding into?
NewsHour Backgrounders
June 27, 1997
David Gergen speaks with Timothy Ferris about his book "The Whole Shebang."
July 2, 1997
A look at July 4th landing of the Mars Pathfinder.
April 10, 1997:
Elizabeth Farnsworth glimpses the distant moons of Jupiter.
March 27, 1997:
Jeffrey Kaye explores the excitement over the Hale-Bopp comet.
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NASA
From Donald Webb of Guelph, Ontario, Canada asks: Does gravity necessarily have a constant force? If the universe is expanding, might not the force of gravity be weakening in some proportion? If so, how could we tell?
Timothy Ferris responds:
Many theorists have investigated the prospect that the gravitational constant might vary -- or have varied -- over the course of cosmic history. Most such theories make predictions that have not been fulfilled: For instance, if gravity were stronger when the universe was young we would expect stars to have been brighter then, and no such effect is seen in deep-space investigations conducted with Hubble and other large telescopes. But a variable gravitational constant remains an interesting possibility.
In "The Whole Shebang" this is discussed in the form of speculation about whether inflation never completely stopped -- a situation known technically as the universe having a "positive cosmological constant." The cosmological constant is a kind of anti-gravity, driving expansion at a faster rate than would be the case were the constant zero. The actual value of the cosmological constant is not yet known; it may very well be zero, in which case the dynamics of the expanding universe are exactly what one would expect from a non-variable gravitational constant.
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