Complex planetary nebula NGC 5189

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Image credits and detail from APOD

More soundings from the frontier of physics today, and this is the weirdest since I read John Taylor’s 1973 book “Black Holes: The End of the Universe?“, which warned us to beware the gravitational collapse of a ‘rugby-football shaped star’*, since this might give rise to a naked singularity where the end of physics would be laid bare for all to observe, without the decency of a surrounding event horizon.

There are three fundamental principles of physics under question, one of which apparently has to go, otherwise the archetypal unwary space traveller, falling through the event horizon even of a black hole large enough that tidal effects (‘spaghettification’) would not yet be noticeable, would immediately be confronted and incinerated by a ‘firewall’ of Hawking radiation invisible to those outside the horizon. The first principle is the equivalence principle, that there is no difference between free fall and inertial motion. The second is the principle that black holes are information sinks. The third principle is simply that ‘normal physics’ holds sway sufficiently far outside black hole.

Physicists don’t lightly abandon time-honored postulates. That’s why so many find the notion of a wall of fire downright noxious. “It is odious,” John Preskill of the California Institute of Technology declared earlier this month at an informal workshop organized by Stanford University’s Leonard Susskind. For two days, 50 or so physicists engaged in a spirited brainstorming session, tossing out all manner of crazy ideas to try to resolve the paradox, punctuated by the rapid-fire tap-tap-tap of equations being scrawled on a blackboard. But despite the collective angst, even the firewall’s fiercest detractors have yet to find a satisfactory solution to the conundrum.

The article was in Scientific American but first appeared here. There is also an interview with Joe Polchinski, author of the paper (abstract here) which began the controversy, here.

*It is easy to find reasons to imagine such an object would be unlikely to exist.

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One Response to “Complex planetary nebula NGC 5189”

  1. […] have drawn attention to the black hole firewall paradox previously, and Scientific American has a new article, highlighting new work which argues for the reality of […]

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