[_puk]

Thanks for both those links.

That article is from 2012 and quotes:

"If that’s the case, we ought to be reading the details about the first space-time crystal sometime in the days and weeks to come. "

Was there something non obvious they had to overcome that took the extra few years to produce these space-time crystals?

(I use the term non obvious as if this was not all way beyond my ken!)

[brathouz]

The 2012 article said they were using beryllium ions, Wikipedia says in 2013 they were planning on using calcium ions, and now the 2016 article says they used ytterbium ions. Without more content to go on, we can only guess about these changes.

In any event, they sure seem to have made a lot of progress in just a few years. I look forward to reading more about this, as well as listening to Neil deGrasse Tyson describe it in his infectiously enthusiastic way.