4-D Space-Time Crystal May Be Built - Or Not
What to give the person who has everything? A clock that will keep perfect time even after the heat-death of the universe.
Such a "space-time crystal" has periodic structure in time as well as space. Why haven't we built those? With such a 4D crystal, scientists would have a new and more effective means by which to study how complex physical properties and behaviors emerge from the collective interactions of large numbers of individual particles, the so-called many-body problem of physics. A space-time crystal could also be used to study phenomena in the quantum world, such…