Timeshifting

The practical design document NotBeforeTime v2.6 explains how existing technologies can be assembled to create a universal way to time-lock information accessed by everyday software most people already use. Underpinned by tried-and-true mathematics, this is a pragmatic tool that anyone will be able to use. The design document explains in mostly non-technical language how: Not Before Time combines existing technology to give three strong guarantees that particular information: will not be readable before a certain future time was not created before a certain past date and time was not electronically signed before a certain past time These support human rights, democracy, health and business. ...

Reversible Computing and Reversible Debugging are amazing and useful applications of Time Shifting via virtualisation, aiming at the massive problem of software unreliability. I believe my excited comments from 2005 still stand: Reversibility is the biggest advance in debugging since source code debugging — GDB developers list In 2026, reversibility has come both a long way and not far at all. I am still very interested in it. What is reversibility? It is possible to have a network of running computers - say, Android, Windows, Linux running on miscellaneous hardware - and then to stop them all and reverse back to any point in time. For example, reversing to a point just before a catastrophic error occurred, so we can watch carefully. And repeat it if we want to, again and again, any number of times. Imagine installing an operating system you know nothing about, starting an application… and then running the process in reverse as it unboots, scrolling up the screen until it switches off. This is true reversibility. ...