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posted by janrinok on Thursday September 12 2019, @05:44PM   Printer-friendly
from the probably,-possibly,-maybe dept.

From WIRED, again. Sometimes they have good stuff.

In the early 1970s, people studying general relativity, our modern theory of gravity, noticed rough similarities between the properties of black holes and the laws of thermodynamics. Stephen Hawking proved that the area of a black hole's event horizon—the surface that marks its boundary—cannot decrease. That sounded suspiciously like the second law of thermodynamics, which says entropy—a measure of disorder—cannot decrease.

Yet at the time, Hawking and others emphasized that the laws of black holes only looked like thermodynamics on paper; they did not actually relate to thermodynamic concepts like temperature or entropy.

Then in quick succession, a pair of brilliant results—one by Hawking himself—suggested that the equations governing black holes were in fact actual expressions of the thermodynamic laws applied to black holes. In 1972, Jacob Bekenstein argued that a black hole's surface area was proportional to its entropy, and thus the second law similarity was a true identity. And in 1974, Hawking found that black holes appear to emit radiation—what we now call Hawking radiation—and this radiation would have exactly the same "temperature" in the thermodynamic analogy.

[...] But what if the connection between the two really is little more than a rough analogy, with little physical reality? What would that mean for the past decades of work in string theory, loop quantum gravity, and beyond? Craig Callender, a philosopher of science at the University of California, San Diego, argues that the notorious laws of black hole thermodynamics may be nothing more than a useful analogy stretched too far.

After what Hawking said about philosophy, I think that astrophysicists need a bit more perspective.


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  • (Score: 2) by maxwell demon on Friday September 13 2019, @06:07PM

    by maxwell demon (1608) on Friday September 13 2019, @06:07PM (#893774) Journal

    Actually, dishwashers use less energy (and less water) than washing by hand.

    Assuming you wash your dishes by had properly, of course. And of course assuming you actually fill your dishwasher, instead of turning it on when partially filled.

    --
    The Tao of math: The numbers you can count are not the real numbers.
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