January 8, 2014

A Black Hole is Not a Hole by Carolyn Cinami DeCristofano

Posted in Uncategorized tagged , , , , at 1:29 am by suebe2

A Black Hole is Not a Hole
by Carolyn Cinami DeCristofano
illustrated by Michael Carroll

If a black hole isn’t a hole, then what is it?

DeCristofano answers this question from two different theoretical perspectives.  The first she uses is the more common.

A black hole is a place with powerful gravity.  It is so strong that nothing, including light, can escape.  That’s why it looks like a hole.  The light that would normally reflect back to the viewer can’t reflect off the matter that is here.  Without this ability to reflect light back to a viewer, the viewer is unable to see what is there.

At the center of a black hole is a collection of incredibly dense matter.  It is so dense that the gravitational pull it generates is inescapable.

Because black holes are so very far from earth, and nothing can get close to one and then move away, scientists study them by taking readings of various kinds (xrays, etc.), making observations, and conducting thought experiments.  The part that I found most interesting is that light traveling near a black hole is bent and often splits.  Remember that light carries images to the human eye.  If the light traveling around the hole doesn’t join up again perfectly, scientists observing black holes will see the same image in multiple places.  This lets them know that someone back behind these images is a black hole.

Although this is a highly illustrated book, don’t let that fool you into thinking its a picture book.  This is a book for older elementary students and middle school students.  The material it covers is actually complex enough to keep high schoolers and adults engrossed as well.

In addition to discussing the history of the study of black holes, DeCristofano also goes into Einstein’s slightly different theory of space, matter and gravity.  According to Einstein, gravity isn’t the effect of two objects acting on each other.  It is the effect that matter has on space itself.   An object in space presses something of a depression into space, the deeper the depression (stronger the gravity) depending on the density of the object.  Because the matter at the center of a black hole is so dense, it is a pressing a vary deep dimple into matter.  In that sense, a black hole, if not a hole, is at least a very deep well in the matter around it.

Writers are constantly told not to dumb down their material and DeCristofano definitely took this lesson to heart.  Any middle school science classroom would benefit from this book and it is sure to generate a host of debates and discussions.




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