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aristarchus [soylentnews.org] writes:

Sorry, from WIRED [wired.com], again. Sometimes they have good stuff. This if from a philosopher of science, with some interesting critique of some current astrophysical dogma. Strap in tight, my Soylentil Cosmonauts!

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.

As you may already discern, the author is concerned that Thermodynamics may not actually be applicable to black holes. And who am I to disagree?

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.

Often, upon a Thursday morning, I would ask myself, "What is 'temperature' in a black hole?" But then, I never could get the hang of Thursdays.

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.

Now this is what I am on about, as a philosopher. What if, it is only an analogy? What if it is stretched too far? What if Cheez-Whiz is not actually cheese in any meaningful sense of the word? Conclusion?

Playing the role of the Socratic gadfly in the foundations of physics is sometimes important. In this case, looking back invites a bit of skepticism that may be useful going forward.

Maybe, but after what Hawking said about philosophy [telegraph.co.uk], I think that astrophysicists need a bit more perspective.

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