By Shristi Pandey
While the theories of quantum mechanics are all that we have in understanding the world and it’s working; they have been doubted for complexities risen lately in the modern world. Be it the question of violating complexities and contradictions in the theory of relativity or the unknowable components behind the truth of multi-universes, it is unfair to rely on a ‘decades old theory’ to naturally account for all the strange features of the world that we live in. The conceptual aspects of quantum physics make it drastically different from the principles of classic physics, which continues to abide by the laws of causality and the space-time equations abided by the same. These however, have been long discarded by the preachers of quantum mechanics, Heisenberg and Bohr, themselves. If we take Heisenberg’s principle into account, it strictly denies the possibility of the fact that exact simultaneous values can't be assigned to all physical quantities. According to Heisenberg, at a particular instant when a given particle is scattered, provided the position of the particle is known, there is a sporadic change in momentum that follows- the greater the change, the more exact is the determination of the particle’s position. Thus, the more precise the determination of the position is, the less precise is the knowledge of the momentum is known. This though, can be viewed from a different angle, altogether. If we are to believe that the change in the momentum of the particle during the measurements is continuous, we are more likely to obtain a different picture out of it. Also, if we consider the possibility that the initial momentum of the particle might have been the same until the position measurement, then we can say that Heisenberg’s argument might need an updating.
Even if we are to believe that the momentum at a particular instant isn’t defined properly yet, we could take the average of the two values of momentums at this instant. But then, this would mean that the momentum is precisely determined at all instants, which doesn’t quite go well in hand with the uncertainty principle. In this process, we consider the sequence as: measurement of momentum after the position of the particle has been already measured, followed by an uncertainty in momentum of the given particle. While Heisenberg points that initial values of momentum and position can never predict about the future behavior of the electron, it brings us to the question whether we can consider this momentum is physically real or not. If we go by the principle of relational physics, we realize that no particle can follow a definite path in absolute space. It is always viewed to have a trajectory through the point of view of a relative particle. This opposes the notion of locality proposed by Heisenberg in his principle. By the virtue of this, when we have two quantum systems interacting in space, the properties of one affect what's measurable in the other particle. We note that the time advance of the final state of a particle is not observable—due to the uncertainty principle, and that is always uncertain. Uncertainty is the effect, but like they say behind every effect, there is a cause.
This relation between the cause and effects is termed as causality, in scientific terms. But the controversial notions of the same haven’t been supported by the advocates of quantum physics. Similar to, but quite different from what Newton propagated through his second law, it can be still rooted for considering that it works well in favor of the superposition principle in the quantum realm. While the theory of causality is particularly in accordance with the concept of arrow of time- laws of physics do not have any preference for the flow of time, it completely goes against the ideas of quantum physics where all the happenings are governed by space-time relations. Through the principles of causality, it was assumed that all events are caused by earlier ones according to the known laws of nature, and that the future states of the world could be computed if the current states were known with precision. The relativistic principle of causality states that the cause of an event must precede its effect, stressing on the existence of a time-like relation to evaluate the same. If a time-like interval does actually exist between the two events, then there is a valid possibility of transmission of signals, both in forward or backward time zones. The one involving the latter is generally termed as retro causality or reverse causality, which works totally against the special relativity and is a whole new arena to be discussed over.
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