In A Very Short Introduction: Black Holes by Katherine Blundell, the author noted that "Black holes are very messy eaters", and explained that saying:

It transpires that only a fraction (estimated to be 10%, though it can be very significantly higher) of the matter that gets attracted in towards a black hole gets as far as the event horizon and actually gets swallowed. Chapter 8 considers what happens to the matter infalling towards a black hole that doesn’t actually get swallowed within the event horizon. From across the accretion disc itself, matter can blow off as a wind; from within the innermost radii of the accretion disc very rapid jets of plasma squirt out at speeds that are really quite close to the speed of light. As Chapter 8 shows, what doesn’t get eaten by the black hole gets spun out and spat out rather spectacularly.

What's exactly meant by "spun out" in this context? Does it mean "be released away through a spiral path", since the plasma jets shown in chapter 8 take a zigzag/corkscrew pattern?

  • $\begingroup$ "As Chapter 8 shows..." So, what does Chapter 8 show? I think that in this case just pasting a block quote is not "evidence of research effort. Why don't you go ahead and check out Chapter 8 like the last sentence suggests, and add to your question what you can learn from it? i.sstatic.net/7Y0NF.png $\endgroup$
    – uhoh
    Jul 2, 2022 at 11:48
  • $\begingroup$ @uhoh I've already read Chapter 8, and therefore understood what "spat out" means, but couldn't get the meaning of "span out" though. $\endgroup$ Jul 2, 2022 at 11:57
  • $\begingroup$ You just said that you understand what "spat out" means and then said that you do not understand what "spat out" means... These contradict each other. Which is it? $\endgroup$ Jul 2, 2022 at 13:09
  • $\begingroup$ @DaddyKropotkin I meant "spun out". $\endgroup$ Jul 2, 2022 at 13:25
  • 6
    $\begingroup$ I've read a number of questions that Ahmed has posted recently. Most of the questions seem to quote parts of the same book where the author has used an idiom or figure of speech to explain complex physics. Given the content in the question, English Language Learners might a really good fit. Phrases like "spun out" are not technical terms. They are general purpose figures of speech that can apply to many different scenarios, not just astronomy. $\endgroup$ Jul 2, 2022 at 14:54

1 Answer 1


Spun out is the term one uses to describe spinning a bucket by a rope or a rock by a sling and then releasing it. Here it refers to matter that is orbiting around the BH (say in the accretion disk) held in by gravity which is suddenly released from the pull of gravity by wind pressure or extreme gas pressure. The matter shoots outward but may also continue to move with a velocity and/or direction close to the tangential velocity it had in orbit just before release.


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