Reflections on Feynman

[Progenitor A]

Reading an article by Feynman recently.
He pondered that on a dark evening if we hold a lamp near to a window, we will see a dim reflection of ourselves. As he explains, about 75% of the photons emitted from our surface simply go straight through the glass, and 25% or so of the photons are reflected to form the image that we see.

NO-ONE KNOWS WHY SOME ARE REFLECTED AND OTHERS GO STRAIGHT THROUGH.

In just the same way as 1/2 life decay of some atoms - we just do not know why one half (or what half) decays whilst the other half is unaffected.

We simply do not understand what is going on at quantum level. That does not mean that we cannot describe what is going on - we can do that easily - it is simply the case that no-one understands what they are describing.

[speakertoanimals]

In just the same way as 1/2 life decay of some atoms - we just do not know why one half (or what half) decays whilst the other half is unaffected.

We simply do not understand what is going on at quantum level.

Given previous Feynman quotes, and looking at his lectures, it is well to remember that we can take this use of understand in two ways.

First is what we commonly mean by understand, in terms of things we understand in an intuitive way -- that is, we manage to reduce the process of understanding to 'understanding' a sequence of things which fit in with our intuition, and which of themselves do not require further 'understanding', or permit further 'why' type questions.

To give an example -- I throw a ball, and it reaches you. Why? Because I impart velocity to the ball. Why? Because objects in a state of motion tend to continue in that state of motion unless forces act. The forces acting here are gravity, which cause the path of the ball to curve.

Most people would find this perfectly acceptable, and say that they understand throwing balls.

Except there are several things hidden here -- why does motion persist? Inertia, some may say. What is inertia, WHY inertia? We could get into Higgs bosons and all that, but at some point we'd just have to say -- because that is what matter just does, it has inertia, and forces are related to acceleration. But WHY? There is no why, we could quite easily write down a mechanics that DIDN'T work like that, just that in our universe, mechanics does work like that.

Same for quantum objects. Just that understanding in this sense doesn't fit in with our intuition (one meaning of understand), whereas on another level, lack of determinism, and identical things (the incident photons) doing different things when they reach the window is just the way that nature seems to be at the deepest level.

Seems that nature is quantum, and non-deterministic, just as inertia just is. We don't often question the latter, because our intuition and everyday experience is built on it, but in basic terms, it is just as mysterious as the former.

So, we either have that no one actually understand anything, if by understand you mean something more than describe in detail what happens, on the other hand, we just have the fairly boring statement that we tend to not question (and say we understand) just those things that we have an intuitive feel for. Which isn't that much.

Whereas a physicist would say that the only proper way to understand the world (since our intuition is hopelessly subjective) is what we understand in terms of mathematical physical theories. And i that case, we understand the quantum world better than we understand the classical world, since we know how the latter can appear from the former -- things are fundamentally quantum, they just look classical (and simpler) if we only look at them on a coarse scale.

And if someone wants to quote yet again Feyman saying no one understands quantum mechanics, I'll say yet again that he just meant we don't grasp it intuitively............

now can we please stop having these pointless debates that all centre around differing usages of 'understand', just because some on here like nothing better than claiming that scientists don't understand anything................