Time travel works.
In fact, it is remarkably common.
However, it doesn’t do what everyone thought it did. The ubiquitous mistake was to assume that time is another dimension (I blame Einstein and Dr. Who); that you could move in that dimension in the same way that you could move in space, left, right, up, down, forwards, backwards, past, and future. Of course, this was nonsense, and many scientists had a field day pointing out that just because you could write Maxwell’s equations for electromagnetism in four-vector, relativistic invariant form, that didn’t mean much to anyone on the top of the clapham omnibus stuck in bad traffic. Nor did any of them get a Fields medal for saying so.
So how does time travel really work?
Essentially, it is time that travels, not you. Think of time as a collection of instants (temporal quanta). Each of those instants can be experienced in many orders, including repetitions. However, instants are unique (the “no cloning” theorem of quantum time theory applies), so how do the repetitions occur in time?
Time travels from one place in the sequence to another. Think of those moments when a smell “transports” you to another time – perhaps the smell of a plant (even Thyme) reminds you completely of all the other times that you were in the presence of that resonant experience. That isn’t what happens. What is actually occurring is that those other “times” are traveling to you. and then back again. You just tick along, as usual, thinking the world is made of some endless reel of film unrolling from the past to the future, holding your delusional beliefs that somebody may build a machine that lets you skip back to some earlier stage of the reel, or unroll it so you can jump forward to some as yet unlived experience. Of course, once this was understood, and indeed, comprehended by the great unwashed public, there was an outcry. Just as Copernicus took us out from the centre of the universe, and Darwin’s theory of evolution took us out of the pinnacle of the pyramid of species, and Relativity cast doubt amongst moral absolutists, and quantum bought us more doubt all the disinformation programs the kremlin could ever muster, Natoshi Sakamoto’s brief theory of time has “bought to an end” causal ordering.
Time is a Pack of Cards continually being shuffled by someone or something. The rules of shuffling are as yet unclear, although certain patterns appear to be emerging, certainly not unconnected with the widely accepted Quantum Smell syndrome. However, for many aspects of human life, time is running out. How shall the law accommodate such a world, where moments are no longer unique or organised into more than an illusory sequence of action and consequence?
Of course, for many in the metaverse, this has been understood “for some time.” Shortcuts, why, even back in text only MUDs and MOOs, had been commonplace, both in between rooms, but also between events. “Be kind, rewind” had to be generalised as a piece of advice, to prevent excessive trauma for new entrants into virtual worlds. Now, it seems, there was no difference between the virtual and the real. Not that we are living in a simulation, of course – that was a consequence of the computational complexity inherent in the Sakamoto model. We could appear to choose to leave that space, and move to the metaverse – this was not a contradiction, since anything built by meta was of necessity, of lower complexity than the Sakamoto universe, and therefore could be fit within, multiple times, if necessary.
“What next?” I hear you cry. That, I reply, is the wrong question.
Marconi Professor of Communications Systems in the Computer Lab at the University of Cambridge