““If we forget to give our measurements in units, or if we are not in agreement over which units we have both used to make our measurements, it is a recipe for disaster. For example, in 1999, the Mars Climate Orbiter space probe was intended to orbit Mars at a low altitude while mapping its surface. It was known that the probe could not get closer than 80 kilometres from the Martian surface or atmospheric stresses would rip it apart. However, the probe actually came within 57 kilometres of the surface and did, indeed, disintegrate. The crash investigators found that the cause of the error was due to the flight system software calculating thrust in metric units, while the ground crew were entering thruster data using imperial measures.””
![“In fact, if you have a very large volume of mass at constant density, then it is guaranteed to become a black hole if the volume is large enough — no matter how small the density! [13] This means that if we had a large volume of soft cotton wool, with a uniformly low density, it would collapse to…” quote by Andrew Thomas](https://sms4smile.com/quotes/img-quotes/5ba/andrew-thomas-21902_black-hole_in-fact-if-you-have-a-very-large-volume_1663514.jpg)
