Oh my god! This story is just as chilling as it was when it was first published in 1954.
As the title suggests, the universe does not care about good intentions. There is no compromise when it comes to physics and mathematics.
In this story we run into the desire of a young girl to surprise her older brother. But the laws of physics and the good of the many, to borrow a quote from Star Trek, has something to say about it.
This is an excellent story and one that should not be missed by any science fiction fan.
I read this in the July 2011 issue of Lightspeed magazine which includes a follow up short story called The Old Equations by Jake Kerr.
The original story is now in the public domain and can easily be found with a Google search. Or, if you like you can find it HERE.