Not negative, complex. As in the square root of a negative number. The value 1/square_root(c^2 - v^2) would be a complex number. You would experience imaginary time. Fiction portrays this as going back in time, but the reality would no doubt be far stranger.

Or is this an extreme for which string theory or quantum gravity have a different answer?

12.7 billion years ago our point of view didn't exist either. The universe was only around 1 billion light-years across. You might think that would mean all light would arrive at a destination in 1 billion years or less. You would be wrong. :-)

Use one of the many peer-to-peer file control systems like hg, git or even fossil. It's the obvious way to do it:

• no central server
• secure
• backed up

<em> and <strong> have always been a part of HTML. The idea is that you are tagging structure, not layout. Text should be emphasized, or made to look strong. <b> and <i> are layout tags, which say to use a bold font or italicized font.

<em> and <strong> are preferred since CSS 1, because best practices say you should separate presentation/layout from structure. The former should only be in CSS, while the latter are in the HTML itself.

Qt's collection classes are API compatible with STL. So I would argue that it plays nicely already. I prefer Qt containers to STL containers because Qt's classes have been optimized. STL has some issues with performance.