A pattern language for building systems that have to keep track of changes to business objects. Also, an experiment in writing minimalist patterns that are embedded in a Development Narrative (a Literate Program with Re Factoring).
The latest version of "Time Travel: A Pattern Language For Values That Change" can be found at www.manfred-lange.com 
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The patterns are:
Also a method of going backwards or forwards in the Space Time continuum. A favorite Plot Enabling Device in Science Fiction stories such as Star Trek, Time Tunnel, The Time Machine, Back To The Future, Time Cop etc and theoretically possible in the distant future using technology based upon Special Relativity such as the Warp Drive or Worm Hole. There are many philosophical Time Travel Problems and Time Travel Paradoxes that are being worked through in a Time Travel Thought Experiment, but the question is: if you could, which time period would you most like to travel to? Many video games now allow you to experience it virtually, so until Exotic Matter is mass produced this gives a chance to see what it would be like. One hypothesis for UFOs is that they are us from the future.
There are many accounts of people who seemed to step back in time for brief periods. One couple stayed at an inn in France where the staff dressed in period clothing, fixtures were all dated, currency was from a hundred years ago. When the witnesses tried returning there soon after no inn was there and local records showed it existed only long ago. Another case, someone stepped off an elevator to find themselves in another period at a train station. Similarly a couple were driving in one country, entered a fog, and found themselves thousands of miles away, had to fly back and ship the car. All anecdotal, but even myself will often be thinking of someone and encounter them on the subway, or writing a letter and at the same time I write a word it is spoken on tv or radio. Perhaps little Worm Holes form in Space Time like dust-devils not a full blown tornado, just a brief vortex in the continuum.
More mundane but equally compelling methods of Time Travel are possible. Recently in my city they had a display of its history and one artifact was a panoramic view of the city from a prominent intersection taken in 1857. It was printed on cardboard in a 3/4 circle and hung from the ceiling at eye level so you could enter through the open 1/4. They had captions every 10 degrees or so explaining what you were looking at. You could see famous buildings still standing and others long replaced by skyscrapers. They also had a few old brown and white stereograms, just like stepping back in time. Similar effect looking at Vermeer paintings - they say he used a Camera Obscura. Like looking at photographs from the 1600s, but instead of using photographic emulsion (not invented yet) he traced the image from a pinhole with his paints. Still a lot of skill required. Real photography was not invented till the 1820s. Art galleries and museums instead of being boring can be thought of as a form of Time Travel.
If you would like to meet Time Travelers from the future, perhaps you can try by developing and participating in a Time Travel Thought Experiment.
See also Grand Unified Theory, Theory Of Everything, Meta Physics, Quantum Physics, Quantum Mechanics, General Relativity, Special Relativity, Space Time, Particle Physics, High Energy Physics, Astro Physics, Wave Particle Duality, Nuclear Physics, Time Dilation, Time Travel Thought Experiment, Time Warp Synchronization.
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