Stanford U. Professor discusses vacuum energy & string theory
Date: Sunday, March 06, 2005 @ 18:50:43 UTC
Topic: Science
"We have examples of systems in nature which have thousands of degrees of freedom," Susskind says, citing a molecule made up out of a thousand atoms. "How many energy levels, how many quantum states, does such a molecule have? The answer can be as high as 10^1000 [ten raised to the power of one thousand]—[there are] huge, huge numbers of possibilities for the ways the atoms organize themselves. In the same way, there are huge numbers of possibilities for the way that these—they're called compactification manifolds—organize themselves. And because there are so many ways, there are many, many energy levels. For the molecule, there are many, many possible values for the energy, 10^500 [ten raised to the power of five hundred] possible values of the vacuum energy."
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"As the world's most famous physics equation, E = mc2, shows, energy and matter are related. When the universe expands, the particles of matter dilute, or take up less space in a given volume. Ordinary energy, therefore, dilutes when the universe expands.
In contrast, dark energy—also called vacuum energy—is a property of empty space. When empty space expands, it just replaces itself with more empty space; it does not dilute. So dark energy is a form of energy that does not dilute as the universe expands.
"Eventually when the universe expands enough, all that will be left is the dark energy," Susskind predicts.
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Read the article here: Leonard Susskind
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