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Are We All Wrong About Black Holes?

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

aristarchus writes:

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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Original Submission

• Re:remember Re:remember (Score: 1, Funny) by Anonymous Coward on Friday September 13 2019, @12:52AM (1 child)

  by Anonymous Coward on Friday September 13 2019, @12:52AM (#893449)

  That's why I drew in some black holes in the box. Shh! The sheep is sleeping.

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• Re:remember (Score: 2) by aristarchus on Saturday September 14 2019, @08:25AM

  by aristarchus (2645) on Saturday September 14 2019, @08:25AM (#894008) Journal

  FOURTH WALL!! You Philistine Soylentils! Or, is it me for pointing it out?

  Le Petit Prince [gutenberg.net.au]

  So then I did my drawing over once more.
  **
  But it was rejected too, just like the others.

  "This one is too old. I want a sheep that will live a long time."

  By this time my patience was exhausted, because I was in a hurry to start taking my engine apart. So I tossed off this drawing.

  **

  And I threw out an explanation with it.

  "This is only his box. The sheep you asked for is inside."

  I was very surprised to see a light break over the face of my young judge:

  "That is exactly the way I wanted it! Do you think that this sheep will have to have a great deal of grass?"

  "Why?"

  "Because where I live everything is very small . . ."

  "There will surely be enough grass for him," I said. "It is a very small sheep that I have given you."

  He bent his head over the drawing.

  "Not so small that--Look! He has gone to sleep . . ."

  And that is how I made the acquaintance of the little prince.

  But the crucial comment is from Chapter One:

  Grown-ups never understand anything by themselves, and it is tiresome for children to be always and forever explaining things to them.

  Especially to engineers, and triply so to software engineers. Twinkle on, B-612. [wikipedia.org]

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