The Amazon box: delivering an imaginary boundary between classical reality and quantum physics

Jim Al-Khalili was on Radio 4 a little while ago talking about quantum physics and his new Time project. He was being asked why, in quantum physics, time does not exist, and responded by describing the way we divide quantum physics from ‘normal’ thinking. The question was, “Is there some threshold at which matter starts to be subjected to the laws of time?” He replied, “That’s what’s called the quantum classical boundary, the ‘classical’, that means the everyday world, of us beings made up of trillions of atoms, so where is that boundary and how does that transition take place?” Quantum physics suggests that time does not apply when we try to observe things that are too small to see, and as Professor Al-Khalili says there is assumed to be a boundary somewhere between the way Quantum physicists have to think about events and the way we ‘normally’ think about them. I am not sure if this boundary exists, because I think that the way quantum physicists think about the world might have a wider application than we often assume. Let’s imagine a thought experiment to understand what I mean by this. There is a box at the Amazon distribution centre waiting to be used and dispatched. We can locate it easily in two or three dimensions, in the distribution centre, and we can describe it in three – it has length, width and height, although not a lot of the third since at present it’s flat packed. Our conventional way of imagining this box is that we will then observe it through time, as it is opened, filled and dispatched to Wherever, and then recycled and returned in a flat pack to Amazon. Time is therefore the fourth dimension of the box’s location. Simple. But this only works while we are actually observing the box. Right now, we are not observing it, we are imagining it, and even right now in the present time doesn’t really apply unless we imagine – or calculate – how a story might unfold over time, but obviously this will be extremely speculative. In this sense, the box is just like a sub-atomic particle we can’t see. It is even more like that sub-atomic particle when we think about where it will be in the future. Nobody knows that. The order that may fill it has not arrived. And even if it has, and we discover its ‘destination’, that’s not its destination at all because it will continue in some form we don’t yet know (and will never know) to exist. We can only talk about where it will be in terms of probability. Time is now quite obviously not a useful dimension on its own. With regard to this imaginary box, the only dimension that makes time work at all is probability. Even more fascinatingly, if we travel in our experiment in the opposite way, we don’t know where the box has been either. Amazon boxes are recycled. But there is no record of what our box was recycled from. So we have as little idea of the box’s past as we do of its future. Again, time is of little use to us here. We are only certain of the box’s present (and even that, if plausible, is imaginary). The past is as much a mystery as the future, and if we really want to work it out our only means is probability. So you can see that, even in the case of quite large visible objects, the division between how we apply time to objects we can possibly see and objects we possibly can’t is itself only a matter of probability, not a matter of time. We don’t know where the box came from or where it will go, nor in each case how long it took, and we almost certainly won’t glimpse it for more than an hour or two of its entire life, if that. Now, it might be objected that the fact that it is ‘observable’ makes a quantum difference because ‘somebody’ can always see it. It is true that this is ‘possibly’ a difference, but the fact that this is not certainly a difference puts us in the same position as we were before. We don’t know who will see it, for how long or where, or indeed who they will be or where they are. We are imagining the box and now we are imagining its observers too, and both are subject to probability. We know that observation will change it in the same way as it changes the particle, by locating it. But, right now, we have no way of locating it anywhere, except by imagining it. So what this thought experiment shows us is that the ‘classical boundary’, which Professor Al-Kalili mentions, is imaginary, and it is as subject to probability in relation to a cardboard box as it is in relation to the smallest sub atomic particle. There is no practical difference. This is really interesting, I believe, because it suggests that the science of very small things is actually the science of very big things too, and it calls into question the whole concept of locality on which the idea of time and the calculations of the standard model of the universe are based. I have written a book about this. It is called ‘Quantism:  the science of the imagination’ and it is available on Amazon if you would like to read more. (It may arrive in the box I have been talking about.)

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