PARALLEL UNIVERSES

Imagine that everything you do is not the result of your conscious choices, but rather of which of parallel universes you happen to be at a particular moment. It sounds weird, but on the other hand, an article like this one can have any beginning whatsoever, right?

At the level of the smallest objects, the laws of physics differ greatly from those we are used to. A particle may not have a particular characteristic untill we look at it. What does that even mean? Imagine that a certain particle is distinguished by its colour. In that case, until you observe it, it doesn not have a specific colour; but at the moment you look at it, its colour is suddently determined. Until that moment, the colour of the particle is described by a so-called wave function, which, in turn, depends on the probability of the particle assuming various colours. Since we are talking about elementary particles, which cannot be observed by a naked eye, their characteristics can only be measured mathematically.

So here is the situation: at first we have a superposition of all possible colours, and then we get just one colour; but where do the rest of the colours go? According to the multi-world interpretation, they do not go anywhere - they remain in various parallel universes. At the moment when we measure an attribute of a particle (that is, when we observe it), the Universe splits into a myriad other universes, and in each of them, one of the possible outcomes is realised. If the particle assumes yellow colour in our Universe, then there exists another universe where it turns out to be red. Such a multi-universe concept does not just fit well into the framework of particle physics - it could work on the level of human-sized objects, too. There is a hypothesis that every time an event (which has a certain probability) occurs, the Universe splits, thus allowing all other possible outcomes to take place. The multi-world hypothesis is also able to solve the so-called 'dead grandpa paradox'. Here is how the paradox goes: if you were to travel to the past and kill your grandfather, then your father wouldn't have been born; thus, you wouldn't have been born, and you wouldn't be able to go back in time and kill your grandpa, either. And yet, your grandpa got killed. The solution is simple, though hypothetical. When you travel into the past, the Universe is split in two, and you find yourself not in your own past, but in the past of a parallel universe: it is there that you kill the grandpa - not yours, but of a 'parallel you'.