The Quantum Mess: Part Four

Are observers really necessary in order for reality to have reality? Is the realm of the quantum really spooky? Is causality doomed? Welcome to the world of the quantum mess!

Continued from yesterday’s blog…

THE QUANTUM MESS - ARE OBSERVERS NECESSARY? In my section on Schrodinger’s cat, I noted how, according to some, it takes an observer to determine the fate of the animal, and until there is such an observation, the cat is both alive and dead at the same time. This thought experiment was an analogy for something in the quantum world that some outcome can have equal but mutually exclusive possibilities (i.e. – an outcome where you can have both being and not being simultaneously), at least until a measurement/observation is made and things fall into place as either being or not being. [There’s an interesting variation on that cat thought experiment. Say the cat-in-the-box is in a room and I’m also in the room, and after one hour I peek in the box and determine the aliveness or deadness of the animal. But, say you are outside the room when I do that. As far as you are concerned, the cat’s wave function hasn’t collapsed and the cat is still dead-alive. So you have got to look too! But then what about a third party in another room in the house, then the neighbour next door, and hence other residents of the town, then state, hence country and then the entire world. Of course the cat would be in a limbo dead-alive state to extraterrestrials on another planet until they looked, and so on. In fact, taken to a logical extreme, nothing has reality until the entire Universe observes, which is again (IMHO), absurd seeing as how it could take billions of years for that cat observation to reach the farthest regions of the cosmos!]

In a similar way, there are those who argue that nothing is real unless that something is observed. For example, the Moon dissolves into quantum uncertainty, the Moon is and is not, if nobody is actually looking at the Moon! As soon as someone looks at the Moon, it solidifies back into physical reality. The absurdity (again IMHO) of that is that if the Moon faded away into quantum uncertainty that would play havoc with the tides and be noticed.  Perhaps observing the tides is sufficient to give the Moon reality without actually observing the Moon!

Extrapolating, there are those who believe and would argue that the entire Universe exists (has reality) only because there are observers to observe or measure it.  Clearly (unless you count God [if He/She/It exists at all] as an observer from Day One), the Universe was in a lifeless state and evolved in a lifeless state from Day One through several billions of years at least. That is, there were no observers at all. The Universe had to exist in a pre-observers stage in order to evolve the complexity required to produce observers. An early Universe consisting of only hydrogen, helium and radiation doesn’t hack it as far as being a suitable environment for observers. So, in terms of this chicken-or-the-egg question, the Universe-or-the-observer question, the answer must clearly come down on the side of the Universe. The Universe can exist either with or without observers; observers exist only because there is a Universe.

Lastly, no one has defined exactly what constitutes an observer. What about an inorganic things like a Geiger counter or thermometer? Can it be anything that’s alive like a plant or bacteria, or does it have to have a sophisticated nervous system (higher sensory capacity)? Maybe there has to be a complex brain within. Maybe an observer is only a bona-fide observer if it has intelligence, but what degree of intelligence? A one day old baby or someone who is brain damaged might look in the box and see Schrodinger’s cat but has no capacity to understand what they are seeing.  What about an artificial intelligence?

I conclude (or believe) that observers and measurements have bugger-all to do with reality, existence and how things work on either a macro or micro scale. The proof of that pudding, if any were necessary, is that radioactive substances decay with a measured half-life. The entire science of radioactive dating depends on this. And radioactive elements decay whether or not observers are present – they have; they do; they will.

THE QUANTUM MESS - UNCERTAINITY (Where’s Jane?): 

Quantum physics is weird for a whole lot of reasons. One of the central reasons is that all things in the quantum realm are stated in terms of probabilities, or uncertainties, or indeterminacy. That’s unlike the realm of classical physics, the realm our normal day-to-day lives are lived in. However, I use an analogy from the classical world to illustrate the realm of quantum uncertainty.

The physical universe is pretty predictable. The rising and setting of the Sun, the phases of the Moon, the tides, the positions of the planets and their satellites, eclipses, etc. can all be predicted to a high degree of accuracy centuries in advance. Applies fall from trees. Two parts hydrogen combines with one part oxygen makes water.  Pure water boils at 100 degrees Centigrade at sea level. Spring follows winter. Entropy increases. Musical instruments play according to design. Bridges bridge according to design. Airplanes fly according to design and so on and so on and so on. Your macro (classical physics) world is as predictable for the most part as is your death and taxes.

On the micro (quantum physics) scale however, quantum effects rule the roost, and that roost is anything but predictable. In other words, uncertainty rules in the tiny world of the micro, for at the heart of quantum physics lays the Heisenberg Uncertainty Principle. In other words, when dealing with all things micro, what you know is only probability. In the world of the macro: The sun will rise tomorrow. In the world of the micro: Any specific atom of a radioactive substance may, or may not decay within an hour, even if it’s near certain that at least one atom will. You can’t predict or know which one. In the world of the macro: You know where the moon is. In the world of the micro: Where is an electron that’s ‘in orbit’ around an atomic nucleus? You don’t know to any precise degree, unlike say, a satellite in orbit around the Earth. The very act of observing or measuring something at the micro level changes the very nature or the properties of what you are trying to observe or measure. You may know the general probability of the value of the property (say the location of an electron in the vicinity somewhere around an atomic nucleus), but never the exact value or location.

From the realm of the classical macro, say an observer observes a pebble on the beach. The observation comes about because photons (light) reflect off the pebble, enter the eyes of the observer, carry sufficient energy to jiggle those retina receptors, causing an electrical nerve signal into the brain which does its brain thingy and ‘sees’ the pebble in a specific place on the beach. The photons, while energetic enough to jiggle the receptors in the retina, aren’t energetic enough to budge the pebble. However, if you replaced a revolver bullet(s) for the photon(s), then the pebble would move, probably to an unexpected, indeterminist place, but with a certain probability of being with a certain radius of where it originally was; an even greater probability of being within twice that distance, etc. Instead of the pebble and the bullet, substitute an electron (pebble), which is small enough to be dislodged by a photon (bullet). You need the photon to see the electron, say in ‘orbit’ around an atomic nucleus, but after that photon enters your eye, the electron has gone walkabout. In other words, the very act of observing the electron changes the position of the electron, so you can’t be certain post-observation where the electron is now and what its new velocity and direction might be. It might not even be in ‘orbit’ anymore. That’s part of the guts of the Heisenberg Uncertainty Principle and better eyeballs or better measuring equipment won’t decrease the level of uncertainty.  The other part  of the uncertainty phenomena is that the electron is behaving as a wave – the wave-particle duality – and thus the electron is not behaving like a little billiard ball and travelling in a nice straight line, or a standard curved orbit at all but waving all over the place like a flag in a still breeze.

So when comparing the macro and the micro worlds, there are two kinds of probability or uncertainty or indeterminacy – call it what you will. There’s uncertainty in the macro world due to lack of knowledge that you in theory could acquire, like is that flipped coin that rolled under the sofa heads or tails? Then there’s uncertainty in the micro world due to lack of knowledge that you can not ever acquire, even in theory. In general, the former tends to represent the classical physics of the macro; the latter, the quantum physics of the micro.

To illustrate, I’ve thought up an example from the world of the classical macro world called ‘where is Jane?’ The starting point is that apparently, according to information on Facebook, Jane is to leave Adelaide, South Australia for Canberra, Australian Capital Territory at 9 am. That much is apparently certain, but that’s all you know. The question is ‘where is Jane?’ at 10 am?

It’s highly probable that Jane will catch a direct flight from Adelaide to Canberra, and knowing the usual speed of a commercial airliner, you can predict where Jane will be at 10 am. BUT, what if Jane missed the flight? What if the flight was delayed? What if the plane hit high headwinds, tailwinds or crosswinds? What if the flight had to go around some nasty weather system? What if the flight was diverted or returned to Adelaide because of a mechanical problem? Then your prediction of where Jane is (latitude, longitude, altitude) at 10 am is fuzzier.

Of course Jane, albeit with less probability, might have flown first to Melbourne hence Canberra. Or perhaps Jane went from Adelaide to Darwin to Brisbane to Canberra - improbable, but not impossible. Even more improbable (but not impossible) is that Jane flew from Adelaide to Perth then on to London via Africa (or the Middle East), hence to New York (or maybe Boston or Washington or Miami) then on to L.A. (or San Francisco) hence to Hawaii, Sydney and Canberra! To predict where Jane is at 10 am, you’d need to consider all those improbably but possible itineraries. 

To complicate things further, there’s a reasonable possibility Jane went to Canberra not by plane, but by train. Or maybe she drove or took a taxi or bus. Maybe she decided to hitchhike, or use her bicycle or walk the distance (say to raise and collect money for charity). 

So, where’s Jane at 10 am? You don’t know exactly, although you can assign various probabilities to all the possibilities and take your best guess. Of course if Jane knows you’re looking for her, perhaps she deliberately took one of the low probability options – and then decided to head for Hobart instead as her port of call! Now you have an idea of how hard it is to pin down any property, such as the position of an electron, in the world of the quantum micro! In fact, it’s even harder than that. You will be indecisive or indeterminate or uncertain that the electron in question is in fact anywhere even near that atomic nucleus it normally ‘orbits’ around. There’s a possibility that the electron went totally walkabout. In our analogy, what if Jane went up – straight up. Maybe, just maybe, however improbable, our Ms. Jane took a suborbital rocket flight from Adelaide to Canberra, perhaps maybe via the Moon, or maybe she is currently heading outward bound towards Mars (and points beyond)!

Actually, to satisfy your curiosity, Jane woke up, decided to hell with going to Canberra, rolled back over and went back to sleep!

To be continued…