Although quantum mechanics is the most robust, widely-supported scientific theory in the history of science, the theory only deals with the math and measurable effects; it says nothing about the underlying reality. It’s one thing to say that an observation affects the outcome of a given subatomic event, but it’s quite another to claim that you understand what that means as far as how the world really works.
Most physicists seem content to just deal with the predictions, the experiments, and the mathematics. But asking “what does it all mean” simply lies outside of what they are comfortable with. Some physicists, however, take the plunge into speculating on what quantum theory means– the “reality” behind the theory.
This speculation is completely outside the realm of verifiable physics. It is metaphysics. But some of the world’s leading scientists have offered their interpretation of the reality underlying the theory. These interpretations are really wild, ranging from ‘there is no real world’ to ‘there are an innumerable number of universes’ and some bizarre stuff in between. Here are the major realities (or interpretations), adapted from Nick Herbert’s Quantum Reality (numbered for reference, not as an indication of viability or popularity):
Initially proposed by Niels Bohr, this is the first half of the interpretation held by most physicists today. Developed at Bohr’s Copenhagen institute, it is referred to as the Copenhagen interpretation. Proponents of this position basically say that the world around us is real, but that reality does not extend into the quantum dimension– there is no objective reality at the quantum level. Needless to say, this causes great angst among many people who wonder how something real can be built out of something that is not real. Albert Einstein was a vehement opponent of the Copenhagen interpretation.
The second half of the Copenhagen Interpretation, it allows for a phenomenal reality, but only when there is an observer. This variation has two parts: 1) reality doesn’t exist without observation, and 2) reality is created through observation. For more on this view, see Taking the Quantum Leap by Fred Wolf.
David Bohm is probably the best-known physicist to advocae the view that the the world is seamless, undivided, and inseparable (see Bridging Science and Spirit: Common Elements in David Bohm’s Physics, the Perennial Philosophy and Seth). A similar view is presented by Fritjof Capra in The Tao of Physics and is generally consistent with eastern world views. Herbert says it well:
“Quantum wholeness, on the other hand, is a fundamentally new kind of togetherness, undiminished by spatial and temporal separation. No casual hookup, this new quantum thing, but a true mingling of distant beings that reaches across the galaxy as forcefully as it reaches across the garden.”
Some physicists believe that whenever there is a possibility of more than one outcome, all outcomes occur– and a new universe is created for each outcome. Flip a coin: it comes up heads in one universe, tails in another (you are present in both). Although it is incomprehensibly bizarre, this view has gained support among physicists because it resolves the quantum measurement problem— in other words, as Herbert puts it, “the math works out better.”
This view holds that the consequences of the quantum revolution are so great that we must replace our mode of reasoning with a new quantum logic. Just like Boolean logic (developed by George Boole in the nineteenth century) launched the science of mathematical logic, some physicists believe that we need a new system of logic to make sense of quantum events. Herbert quotes quantum theorist David Finkelstein:
“Einstein threw out the classical concept of time; Bohr throws out the classical concept of truth… Our classical ideas of logic are simply wrong in a basic practical way. the next step is to learn to think in the right way, to learn to think quantum-logically.”
The quantum world is made of ordinary objects, just like the larger-object world we are familiar with. Herbert uses the term ‘neorealist’ to describe physicists who believe that the familiar world of objects can be extended into the sub-atomic realm. Although it doesn’t sound so radical, claiming that life-size objects are made out of quantum-size objects is heresy to establishment physics. The established view is that at the quantum level ordinary objects don’t exist; they are impossible under quantum theory. Bohr was very clear: “There is no quantum world, there is only an abstract quantum description”. Heisenberg asserted that “atoms are not things” and considered neorealists the modern-day equivalent of flat-earthers.
But these modern flat-earthers were no intellectual slackers: Albert Einstein, Max Planck, Erwin Schrodinger, and Prince Louis de Broglie were all neorealists. Neorealism also underlies David Bohm’s views (also see ‘undivided wholeness’, above and Bridging Science and Spirit: Common Elements in David Bohm’s Physics, the Perennial Philosophy and Seth). Einstein wrote in his autobiography: “I still believe in the possibility of a model of reality– that is, of a theory which represents things themselves and not merely the probability of their occurrence.”
This is a variation and subset of the observation-created reality view (above), with the additional position that only a conscious entity can create reality. Herbert says that he includes this reality “not only because it is so outlandish but because its supporters are so illustrious.” Among the notable advocates of this reality is John von Neumann, the brilliant mathematician who wrote Die Mathematische Grundlagen der Quantenmechanik, considered the quantum bible by many physicists. He was the first to suggest that an observer’s consciousness must play an active role in quantum reality. Eugene Wigner, a close colleague of von Neumann’s, said:
“It is not possible to formulate the laws of quantum mechanics in a fully consistent way without reference to the consciousness… It will remain remarkable in whatever way our future concepts may develop, that the very study of the external world led to the conclusion that the content of the consciousness is an ultimate reality.”
According to Herbert, most physicists today believe in the Copenhagen interpretation, reflected in the first two quantum realities: 1) there is no deep reality, and 2) observation creates reality. The common thread between these two interpretations is the position that phenomena are real but the world beneath them is not. This view leads to the difficult-to-accept premise that we live in a very real world which has a foundation of completely unreal stuff.
Remember, these are not the wild musings of science fiction writers; they are serious views of how the world really works by physicists who have spent much of their life thinking about it. Herbert says that the current views of quantum reality create a two-part crisis for physicists: 1) there are too many realities, and 2) they are all preposterous. Some of them are compatible with each other, some are mutually exclusive. But all of them are completely supported by experiment– they all predict the same observable phenomena. And they may all be wrong.
This summary of the current views on quantum reality is only a brief glimpse into the fascinating and bizarre world of modern physics (and metaphysics). For more information or a better explanation, you should read Herbert’s Quantum Reality.