Just what is it about 'Neutron Stars' that makes me shiver and shake?

Einstein's predicted warping of space-time has been discovered around neutron stars, the most dense observable matter in the universe. The warping shows up as smeared lines of iron gas whipping around the stars, astronomers say. The finding also indicates a size limit for the celestial objects. The same distortions have been spotted around black holes and even around Earth, so while the finding may not be a surprise, it is significant for answering basic questions of physics. There could be exotic kinds of particles or states of matter in the centres of neutron stars. Neutron stars can pack more than a sun's worth of material into a city-sized sphere. A few cups of neutron-star stuff would outweigh Mount Everest. Astronomers use these collapsed stars as natural laboratories to study how tightly matter can be crammed under the most extreme pressures nature can offer. To even begin to address the mystery of what lies within these dying stars, scientists must accurately and precisely measure their diameters and masses. In two concurrent studies, astronomers studied the spectral lines from hot iron atoms that whirl around in a disc just beyond the neutron stars' surfaces at speeds reaching 40 percent light speed. The measurements allowed them to determine maximum star size. "We're seeing the gas whipping around just outside the neutron star's surface," said team member Edward Cackett of the University of Michigan. "And since the inner part of the disc obviously can't orbit any closer than the neutron star's surface, these measurements give us a maximum size of the neutron star's diameter." He said the neutron stars can be no larger than about 33 kilometres across. Space.Com