title: How to represent dates before epoch as a UNIX timestamp
body: <p>It occurred to me that I'm not aware of a mechanism to store dates before 1970 jan. 1 as Unix timestamps. Since that date is the Unix "epoch" this isn't much of a surprise.</p>
  
  <p>But - even though it's not designed for that - I still wish to store dates in the far past in Unix format.<br>I need this for reasons.</p>
  
  <p>So my question is: how would one go about making unix-timestamps contain "invalid" but still working dates? Would storing a negative amount of seconds work? Can we even store <strong>negative</strong> amounts of seconds in a unix-timestamp? I mean isn't it unsigned?</p>
  
  <p>Also if I'm correct then I could only store dates as far back as <code>1901. dec. 13 20:45:52</code> could this be extended any further back in history by any means?</p>