This website tries to explain why the term spaghettification doesn't actually occur when something gets close to a black hole. The argument of the author is that the equations we use to predict the tidal forces causing the spaghettification are incompatible with the spacetime shrinkage around a black hole, and so they can't be used. She concludes that spaghettification doesn't occur but the extreme shrinkage turns matter into plasma and then into elementary particles after some time has passed.

I can't actually say that I understand everything of what the author explained, and therefore I am unable to agree or disagree. So I thought it would be better to ask about it here.

So does this website hold any valid argument against tidal forces causing spaghettification ? Or is it just something not taken into consideration ?

  • $\begingroup$ Perhaps this is prejudiced of me, but at first glance that does not appear to be a reputable website, to put it kindly. It might be better to read Wikipedia: en.wikipedia.org/wiki/Spaghettification. $\endgroup$ – gj255 Aug 28 '15 at 15:54
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    $\begingroup$ The author arrives at her conclusion (and supporting premises) by doing math in a Cartesian system that she's wrapped around the black hole. This leads her to the conclusion that space is contracted near a black hole, so that objects are compressed (rather than tidally stretched) as they approach the black hole. But simply wrapping a grid around on itself isn't accurate to how gravity warps spacetime, so the premise is false. $\endgroup$ – Asher Aug 28 '15 at 19:35
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    $\begingroup$ @Asher that should probably be an answer $\endgroup$ – David Z Aug 28 '15 at 22:51

The math in that article is based in Cartesian space. Note specifically figure 4, where a portion of a Cartesian plane is pinched in at one side to show the supposed warping due to gravity. Using the shown transformation, she concludes that space is compressed near a black hole rather than stretched. The diagrams after that along with the process explanations clarify this.

The "pinching" transformation used, though, is not accurate to how gravity warps spacetime. Note that the horizontal dimension becomes radial and the vertical dimension becomes circular. This is an attempt to transform from a Cartesian coordinate (length x length) into a polar system (distance x angle) but the math used afterward is still Cartesian math, which is incompatible with the new implied coordinate system.

Referencing figure 4b, I note that the wedge-shaped grid is about 30 degrees of a circle, so theoretically (in the author's system) twelve such connected grids would form a full circle. Assuming units in meters, the grid is about 30m wide by 10m high, so the final circle is about 30m in radius and 120m circumference at any distance from center. In the real world, a circle with larger radius has larger circumference. In the author's contrived system, orbital speed/period is independent of altitude. The math being used is not consistent with reality because the it is performed in the wrong coordinate system.

Another false premise at work here is that she uses a finite (30x10 in this case) space to illustrate warping of an infinite space. The only way to apply the shown transformation to an infinite grid would be to have a black hole that is in an extra dimension, I.e. "off the grid." Since black holes exist in the same dimensions we do, the math the author uses again does not agree with physical reality.

The article you've linked attempts to disprove a physical process in a universe with a particular geometry by comparing it to a functionally different process in a completely different geometry. The math stated in the article simply does not apply to spaghettification and thus cannot disprove it.


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