Quantum mechanics has macroscopic analogs

If modern physics (that masterpiece of complexity, abstraction, and imponderability) teaches us anything, it points out the impossibility of severing the link between the observer and the observed. Yet even in a very simple piece of chemistry or cooking, we know this to be the case if we only think about it: how does a thermometer measure the temperature of a hot liquid? It is immersed in it, and some of the energy of the liquid “moves into” the thermometer, causing a change in it that (in a liquid-based thermometer) we can see. Why do we never think that the energy left in the liquid must necessarily be less after we inserted the thermometer than it was before? In the act of measuring the temperature of the liquid, we have changed it. ( I suppose what quantum physics tells us is that this interaction of measurer and measured can only be minimized, not eliminated.) A similar effect can be seen, on a larger scale, when you dump pasta into boiling water: put in more than a tiny bit of pasta, and the water stops boiling! It’s fascinating to me, in retrospect, that no-one deduced the entanglement principle earlier.