There has been a long running debate throughout the history of Quantum Physics as to what exactly is going on in the physical world on the quantum level. This debate is waged both at the scientific and philosophical levels, however there is no real way as of yet, to declare any of the theories of Quantum Reality as fact, but some theories hold more ground amongst the physics community than others. The variety and scope of these underlying realities is a testament to the complicated nature of the subject at hand. All interpretations of quantum reality deal with the very foundations of Quantum Physics, and that is locality and realism. These interpretations or theories range from the Copenhagen Interpretation, which takes a non-real and non-local stance, to the Many World’s Interpretation which states that the world is realist and non-local. The many theories and interpretations of Quantum Reality can weave a confusing web, but by taking a systematic approach to the explanation of the inner-workings of the universe, it will be seen that no matter who you are, there is an interpretation that will sit right with your interpretation of reality.
Unlike other areas of science, Quantum Physics is unique in that at its core lie fundamental questions, and a need for interpretation, rather than concrete experimentally proven realities. Throughout the history of Quantum Physics, there has been a debate about whether or not the science was to be considered complete. This is an argument that Bohr and Einstein are responsible for spearheading as they were the main figures on either side of the argument, Einstein and Schrodinger saying that Quantum Mechanics is not complete, while Bohr, Heisenberg, and Pauli stating that Quantum Mechanics is a complete theory. Bohr, Heisenberg, and Pauli recognized that this was completely unlike classical physics, which follows natural laws, but nonetheless they persisted with their theory (Omnes 39). The reason that Einstein had so much difficulty dealing with the completeness of the theory was because it deviated so much from what was usually regarded as physical reality. He struggled with this fact his entire life, and in trying to come to grips gave us many thought experiments, some of which come into play in the interpretation of Quantum Reality.
One of the most prevalent and widely discussed theories of Quantum Reality is the Orthodox, or Copenhagen Interpretation. This theory, championed by Bohr, Heisenberg, and Pauli, is named for the location of Bohr’s lab, where the group would often meet. These three men were in favor of a non-realist and non-local interpretation, and are credited with formulating the first essential answer to the interpretation question in Quantum Physics (Omnes 41). Bohr, Heisenberg, and Pauli utilized measuring methods taken from classical physics in order to analyze the world on the quantum level (Evans & Thorndike 137). This complication is one of many associated with the interpretation, including absolute randomness. Even with these complications present, this theory of Quantum Reality states that the universe non-realist. Non-Realism says that if an object is out of sight and thus isolated from its surroundings, the objects location becomes not only unknown, but undefined. For the object to acquire a well-defined location, somebody must see it, or it must interact in some other way with the environment around it (Blaylock 3/5/08). That is to say, if we cannot see or otherwise act on a particle or object, then that object is not able to defined in any sense, even going as far as to say that the object does not exist. In addition, the Copenhagen Interpretation states that the universe is non-local, which suggests that actions taking place at one point can have immediate effects on another completely separate portion of space. Actions are not limited to their local vicinity, but may permeate all of space. Bohr, Heisenberg, and Pauli went to great lengths to defend their position against dissenters, and converted quite a few naysayers along the way. Not everyone was convinced, mostly because of a few particular points of contention.
Quantum Physics replies heavily on the principles of probability and uncertainty, and because of the probabilistic nature of the science, applying classically defined mathematical symbols does not produce the type of observations that one would expect. This deviation from what is held as “common sense” of classical mathematics and physics leads to much debate as to the legitimacy of the quantum theory (Omnes 42). Complex numbers are perfect example of this complication in action. These numbers can be used in classical physics in order to make a calculation simpler, even though the calculation can be done without them, but it should be noted that these complex numbers in question are superfluous (Omnes 42). When applying these numbers to Quantum Physics, the problem arises when it is realized that reality requires the use of mathematical symbols that represent real numbers. How and why then do we apply complex numbers, which are not real, to Quantum Reality? These complex numbers are necessary for the computation of real wave functions due to their probabilistic meaning, and making computations of this nature with real numbers causes difficulties that vanish when complex numbers are substituted (Omnes 42). Here we have a theory of quantum reality that requires non-existent, basically valueless symbols be inserted into equations to produce concrete results. This testament to the non-real quality of the universe on the quantum level is much debated, and a tipping point on the scale of many critics.
Einstein famously said, “God does not play dice,” when referring to the random nature of the universe. He had himself built probability into his work with Black-Body Radiation, but he like many of contemporaries, did so because he assumed that all of the laws of the physical world had not yet been discovered (Omnes). In formulating a complete theory of Quantum Mechanics, it is necessary to include the fact that the universe is random. There is such thing as “Absolute Randomness,” and it is at work at all times. Even knowing all there is to be known about a given circumstance or experiment cannot lead the observer to a point where the outcome can be predicted precisely. This universal randomness in the world of atoms has given way to quite a bit of difficulty in the digestion of the Copenhagen Interpretation of quantum reality, but nevertheless, in order to say that the universe is non-local and non-real as this theory does, we must account for absolute randomness (Omnes 43).
The Copenhagen Interpretation certainly has its followers, but to say that this theory of quantum reality is all encompassing would be quite irresponsible as there are a number of other well-known and documented interpretations. The Copenhagen Interpretation covers many bases, but there is definitely room for discussion, and it should be noted that this interpretation although once at the forefront of quantum theory has since lost some ground to the newer theories on the table.
David Bohm’s interpretation of quantum reality argues for realism and non-locality through a revival of de Broglie’s Pilot Wave Theory (Evans & Thorndike 14). The most troublesome aspect of the Copenhagen Interpretation for many is the fact that complementarity “replaced the obvious clarity instinctively attributed to reality” with “an irreducible ambiguity” (Omnes 62). So while attempting to adjust the Copenhagen Interpretation to avoid the principle of complementarity, his interpretation really did not bring anything new to the table, only offered a new interpretation of the existing Copenhagen Interpretation and reignited people’s interests in the foundations of Quantum Physics (Evans & Thorndike 14).
In an effort to bring realism into Quantum Reality, Bohm aimed to abandon complementarity, instead redefining Quantum Mechanics so that a given particle has a well-defined location at every moment of time, as well as a trajectory and therefore a velocity. The fault present in this, is that in order to really analyze the relativistic nature of the particles at hand, we must decide which is real, the particle or the field, and thus complementarity rears it’s head again (Omnes 63).
Although an interesting take on an existing idea, Bohm’s Interpretation does little to expand the school of thought surrounding Quantum Reality. This pitfall is a major reason for the lack of followers to this interpretation, and could even be viewed as it’s undoing. While certainly not the most unusual interpretation, Bohm’s Interpretation does bring some interesting thoughts to Quantum Reality, however it does not raise nearly as many eyebrows as some of the other interpretations out there.
The Many Worlds interpretation came from Everett’s original relative-state proposal (Evans & Thorndike 138). This interpretation states that the world is realist and extravagantly non-local. There is never collapse, because every possible outcome exists in a separate world or universe. That is, every possible outcome is actually realized (Norris 135). The implications of this theory are hard to grasp, and requires thinking outside of all common notions of the universe and reality. The interpretation tells us that everything that we can’t observe taking place, is actually happening somewhere else. We are only viewing one of many outcomes. The only concrete evidence to support this theory of reality is the interference pattern created by “real” and “shadow” photons (Norris 135). This phenomenon alone is not enough to sway the minds of all, as this interpretation of reality has some very vocal dissenters, many of whom argue from a philosophical standpoint, not from a strictly scientific stance.
Quantum Reality is a topic that almost always ends in some sort of philosophical debate. It is almost unavoidable, but this is not a surprise, given that we are dealing with information and circumstances that defy all “common sense” notions of physical law. The critic often asks the question of “how” and “why,” but when it comes to the behavior of the world on the quantum level, we need to focus on the fact that certain things just happen. Someday we may know why it is exactly that electrons in the double slit experiment take on wave-like features. The dual nature of photons may not always be a mystery, but at this point what we know is that sometimes things go one way, and sometimes they go another. It sounds ambiguous because it is just that. We cannot exactly predict anything, but only predict with a reasonable amount of certainty and uncertainty. For these reasons, many turn to a philosophical debate, but with good intentions. When confronted with the unknown we are tempted to take that which we already understand, and try and apply the unknown to these defined laws and observable behavior. Quantum Physics tells us that it is not that easy. Even the greatest minds of the science struggled with the redefining of the laws of nature. So is it any surprise that the more casual observer tries to fit quantum occurrences into a convenient box? It is human nature to try and explain that which we do not understand. For this reason, it is clear that we have not come anywhere near the point where a true interpretation of quantum reality is agreed upon by all. We may never get to this point, but as long as we have individuals asking questions and proposing answers, we are on the right path.
The universe may be local, or it may be non-local. That which we observe could be real, but it could also be non-real. These foundations of quantum reality and quantum physics itself are the fuel for the debate at hand. Like the dual nature of matter and light, there is experimental evidence to support either side of the coin in all of these cases. For this reason, the future of quantum reality is very much wide open for the next great mind to make a remarkable breakthrough. What is needed, is to have a great mind start from scratch, and not rely on the established information of quantum reality. Building on previous work is not the appropriate the foundation when redefining that which is commonly deemed as “real.” It is necessary to expand horizons into uncharted territory, this is the future of the Quantum Reality.
As time goes by, more experiments are performed, and our instrumentation becomes finer tuned, it is likely that additional interpretations of Quantum Reality will be brought to light. Some of these interpretations may immediately hold ground, others will not stand up to scrutiny, and still more may take years of experimentation until they mature. One thing can be known for certain, and that is no matter the outcome – if we ever see an outcome of this argument – our minds and imaginations will surely be tested to the max, and our ability to reason with the unreasonable will be our greatest weapon in the search for the answers to our most fundamental questions.
Norris, Christopher. Quantum Theory and the Flight from Realism. London and New York City: Routledge, 2000.
Omnes, Roland. Understanding Quantum Mechanics. Princeton, New Jersey: Princton University Press, 1999.
Quantum Mechanics at the Crossroads. Ed. James Evans and Alan S. Thorndike. New York City: Springer Berlin Heidelberg, 2007.