Alternative Histories


Well we were having our boards and other entrances . . . pretty big deal here, decides our future and stuff(horror face). But I dunno why I get caught up in reading other books rather than the ones I should be reading. Well one of the books I finished was that of Stephen Hawking’s “The Grand Design”. All I can say is that he is ah-meh-zinggg!! Okay enough of the “Intro” now the main topic. In that book I came across the concept of Alternate Histories and it was just.. AWESOME( nothing to do with real history FYI).

Now the topic begins…. (It’s gonna get a bit science-y, muahahahaha)

Feynman (a physicist) was intrigued by the question of how interference patterns in the double slit experiment arises when we fire molecules at the screen because basically they should just hit at a point.

According to Newtonian Physics(and the way the experiment would work if we did it with soccer balls instead of molecules)-each particle follows a single well defined route from source to screen .There is no room in the picture for a detour in which the particles visit the neighborhood of each slit along the way.

According to Quantum PhysicsThe particle is said to have no definite position during the time it is between the starting point and the end point.

Feynman realized one does not have to interpret that to mean that particles take no path as they travel between source and screen. It could mean instead mean that the particle takes every possible path connecting those points. The situation in both slit matters because, rather than following a single definite path, particle takes every path, and they take them all . . . . simultaneously!! Feynman formulated a mathematical expression that reflects this idea and reproduces all the laws of quantum physics.

In the double slit experiment Feynman’s idea means that particles take paths that go through only one slit or only the other; path that circles Jupiter a few times and comes back; even paths that go across the universe and back. But according to the theory the paths are associated with the planks const. which as we know is very small. But sometimes for certain paths their phase line up and so they are favoured.

Just as for the double slit experiment the chance of observing the particle to land at a given point depends on all the paths that could have gotten it there, Feynman showed that, for a general system, the probability of any observation is constructed from all the possible histories that could have led to that observation. Because of that this method is called “Alternative Histories formulation of Quantum Physics”.

NOW, the main part … what if we could do that? I mean taking all of our decisions/paths simultaneously?? Ahhh, being a quantum particle has its perks I guess. But for the larger objects the probability that it would take a particular path i.e the one described by Newtonian model is just too large in comparison to the probabilities of other paths. That is why when we decide we’ll go shopping we usually take the main road which is mostly filled with cars honking at each other rather than reaching the mall after travelling through Switzerland (well unless ofcourse you live there). But mind you, the probability of larger objects taking a ‘quantum’ path is not exactly mentioned as being totally absent. So there is still a tiny, extremely small (almost zero.. but still there) probability that the next time you crave a pizza, you might reach the nearest pizzeria after travelling through Italy. 😉


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