GREAT news, there may be a way to avoid a looming disaster. All you need to do is forget all about it by 鈥渞esetting鈥� your memory.
That鈥檚 the claim of physicist Saibal Mitra at the University of Amsterdam in the Netherlands, and it is predicated on the existence of parallel universes.
The 鈥渕any worlds鈥� concept is an interpretation of quantum theory 鈥� our best description of the microscopic world of atoms and their constituents. Many worlds takes literally quantum theory鈥檚 idea that a quantum entity like an atom can exist in many states at once, and posits the existence of parallel universes containing infinite copies of you with different histories and futures.
Advertisement
To understand how the many-worlds scenario could allow a future disaster to be avoided, says Mitra, consider a hypothetical machine intelligence that regularly backs up its memory. If it encountered a glitch, for example, it could reset its memory to, say, the previous day鈥檚 state.
Imagine that on learning of an impending disaster 鈥� perhaps a catastrophic asteroid strike on its planet 鈥� the machine resets its memory. Now, an observer sat next to the machine can verify that the 鈥渟ame machine鈥� will still face disaster after the reset. But from the perspective of the machine鈥檚 reset memory, the state of the universe in the many-worlds scenario becomes 鈥渦ndetermined鈥�. After all, for all the machine knows, the reset probably occurred for a mundane reason, such as a crash of its operating system.
The next part defies our natural instincts: according to the many-worlds interpretation, all of these undetermined possibilities actually exist and open up to the machine. Even though it followed one particular history up to its resetting, it can be dealt a new card, says Mitra. So, from its unwitting perspective, the machine could 鈥渟witch鈥� to a parallel universe. The probability of a memory reset due to a rare event like an asteroid strike would be far smaller than the probability of a routine reset due to a glitch, and so there will be many more universes in which the disaster does not occur. 鈥淐onsequently, the machine will almost certainly find itself in one of these universes and avoid the catastrophe,鈥� says Mitra ().
鈥淚f we could find a way to reset our knowledge of an impending disaster, we too could avoid it,鈥� he says. The downside of such memory resets, however, is that there is a small chance you will 鈥渨ake up鈥� in a universe facing an even more cataclysmic disaster than the one you were trying to dodge. 鈥淵ou鈥檇 have to weigh up whether it would be worth the risk,鈥� Mitra concedes.
鈥淚f we could find a way to reset our knowledge of an impending disaster, we could avoid it鈥�
鈥淚f correct, it鈥檚 an intriguing result,鈥� says Max Tegmark of the Massachusetts Institute of Technology, 鈥渆ven if it may only apply to future beings whose minds are quantum computers and not beings like us with warm, wet brains where quantum superpositions get rapidly destroyed.鈥�
David Deutsch at the University of Oxford, whose work has lent mathematical support to the many-worlds idea, points out that conclusions based on the probabilities of outcomes in parallel universes will be speculative, and therefore suspects Mitra is wrong. However, he notes that 鈥減robability is not yet sufficiently well understood to say so definitively鈥�.
