Re: Fredkin, for the units issue, see:
“Chapter 20: Units B, L, T, P, D, R, A & I”
http://web.archive.org/web/20060925023734/http://digitalphilosophy.org/digital_philosophy/20_units.htm
For temporal reversibility, see:
“Chapter 30: DM and CPT”
http://web.archive.org/web/20040410145311/www.digitalphilosophy.org/digital_philosophy/30_dm_cpt.htm
I also have a page on the subject:
http://finitenature.com/cpt/
There’s also a synopsis of Fredkin’s ideas (incl. these two) in:
“Five big questions with pretty simple answers”
http://www.research.ibm.com/journal/rd/481/fredkin.html
Re: Fredkin, for the units issue, see:
“Chapter 20: Units B, L, T, P, D, R, A & I”
http://web.archive.org/web/20060925023734/http://digitalphilosophy.org/digital_philosophy/20_units.htm
For temporal reversibility, see:
“Chapter 30: DM and CPT”
http://web.archive.org/web/20040410145311/www.digitalphilosophy.org/digital_philosophy/30_dm_cpt.htm
I also have a page on the subject:
http://finitenature.com/cpt/
There’s also a synopsis of Fredkin’s ideas (incl. these two) in:
“Five big questions with pretty simple answers”
http://www.research.ibm.com/journal/rd/481/fredkin.html