140 Medical Time Travel vitrification  will  require  fundamental  new  knowledge  of mechanisms of cryoprotectant toxicity, and means to inter- vene in those mechanisms. If reversible vitrification of humans is developed in future decades,  what  would  be  the  application  of  this  ‘suspended animation’? Space travel is sometimes suggested as an applica- tion, but time travel – specifically, medical time travel – seems more likely to be the primary application. People, especially young  people  dying  of  diseases  expected  to  be  treatable  in future years would be most motivated to try new suspended animation  technologies.  Governments  would  probably  not even  allow  anyone  but  dying  people  to  undergo  such  an extreme process, especially in the early days. Applications like space travel would come much later. Medical  time  travel,  by  definition,  involves  technologi- cal  anticipation.  Sometimes  this  anticipation  goes  beyond just  cures  for  disease.  After  all,  if  people  are  cryopreserved in anticipation of future cures, what about future cures for imperfections of the preservation process itself? As the medi- cal prospect of reversible suspended animation draws nearer, the  temptation  to  cut  this  corner  will  become  stronger. In fact, some people are already cutting this corner very wide. In 1964, with the science of cryobiology still in its infancy, Robert  Ettinger  proposed  freezing  recently  deceased  per- sons until science could resuscitate them. [24] The proposal assumed that the cause of death, the early stages of clinical death, and crude preservation would all be reversible in the future. Even aging was to be reversed. This proposal was made in absence of any detailed knowledge of the effects of stopped blood flow or freezing on the human body. The proposal later came to be known as ‘cryonics’. Cryonics was clever in that it circumvented legal obstacles to cryopreserving people by operating on the other side of the legal dividing line of death. However 40 years later, as