[Pdx-pm] 32 bits? Seconds? For shame!
keithl at kl-ic.com
Sat Sep 18 17:15:50 PDT 2010
On Sat, Sep 18, 2010 at 03:29:18PM -0700, Michael G Schwern wrote:
> REPENT!!! FOR THE END OF THE UNIX EPOCH IS NIGH!!!
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
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 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
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