[Pdx-pm] 32 bits? Seconds? For shame!

[Keith Lofstrom]

On Sat, Sep 18, 2010 at 03:29:18PM -0700, Michael G Schwern wrote:
> REPENT!!! FOR THE END OF THE UNIX EPOCH IS NIGH!!!
> http://pghpw.org/ppw2010/talk/3035

32 bits?  Seconds????  

The only natural unit for time is the Planck time (5.39E-44 seconds). 
Computers with clock periods shorter than that have bits that 
collapse into black holes,  so we can take that as a reasonable
lower bound.  The universe is expected to evaporate into leptons
and photons in about 1E36 years.  So, we should represent time
in computers as a 264 bit quantity. 

Since we haven't yet figured out (down to the zepto-yocto-second)
when the universe started, we might as well keep the current Unix
epoch, starting on January 1, 1970 .  As I write this, it is now
0x000000000000000000003FB2AC0EF8519C1027A69E4B15634FC1C56DEF02120F
Planck units since the epoch.

I expect that some tightwad programmer will try to scrape
by with only 255 bits plus sign, leading to the dreaded
Y98910607320000000000000K problem.  If that programmer is still
around, they will have a LOT of accumulated code to fix.

Keith

-- 
Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs