I just saw a few of Feynman's lectures on QED: Reflection and transmission, and he describes the concept of probability amplitude arrows, and their representation as vectors, from what I interpreted, the length of the arrow is proportional to the probability of an event, and its angle is dependent on the time.(adsbygoogle = window.adsbygoogle || []).push({});

In the part where he describes the first law of reflection, the arrows form two spirals. (This is perhaps not the best way to describe it, but the important thing is that it forms a spiral)

Now to form these spirals, the length of each successive arrow should be less than the previous one, but since we do not know the probability of these events (which is what we have to find) and hence the lengths, how can he draw them as spirals?

(link : http://youtu.be/-QUj2ZRUa7c )

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# Probability amplitude arrows

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