Of Werner Heisenberg's many contributions, two stand out. The first was matrix mechanics. It was the first form of what is called “the new quantum mechanics,” as compared to the “old quantum mechanics” of Bohr. Bohr's old quantum theory talked of electron orbits; these were themselves unmeasurable. Heisenberg found a way of putting what was measurable into a sort of table, called a matrix. He also recognized that measurement of the same properties, such as electron spin, could give different results. This led to his second great achievement, his uncertainty principle. Certain pairs of measurements, such as position and momentum, could not be simultaneously measured to any desired degree of accuracy. The more accurately measured the one, the less can be known about the other. This is not an experimental error. It is fundamental. Heisenberg is associated with another uncertainty: his role in attempting to build a German atomic bomb. What he actually did or did not do is still a matter of controversy.
Of Werner Heisenberg's many contributions, two stand out. The first was matrix mechanics. It was the first form of what is called “the new quantum mechanics,” as compared to the “old quantum mechanics” of Bohr. Bohr's old quantum theory talked of electron orbits; these were themselves unmeasurable. Heisenberg found a way of putting what was measurable into a sort of table, called a matrix. He also recognized that measurement of the same properties, such as electron spin, could give different results. This led to his second great achievement, his uncertainty principle. Certain pairs of measurements, such as position and momentum, could not be simultaneously measured to any desired degree of accuracy. The more accurately measured the one, the less can be known about the other. This is not an experimental error. It is fundamental. Heisenberg is associated with another uncertainty: his role in attempting to build a German atomic bomb. What he actually did or did not do is still a matter of controversy.
From the outset, Heisenberg had resolved to eliminate classical space-time pictures involving particles and waves from the quantum mechanics of the atom. He had wanted to focus instead on the properties actually observed and recorded in laboratory experiments, such as the positions and intensities of spectral lines. Alone in Copenhagen in February 1927, he now pondered on the significance and meaning of such experimental observables. Feeling the need to introduce at least some form of ‘visualizability’, he asked himself some fundamental questions, such as: What do we actually mean when we talk about the position of an electron? He went on to discover the uncertainty principle: the product of the ‘uncertainties’ in certain pairs of variables—called complementary variables—such as position and momentum cannot be smaller than Planck’s constant h (now h / 4π).
Most of the physicians that I know are chary of Physics, especially the theory of elementary particles. Even if in Isaac Newton's mathematically precise universe, everything follows clear-cut laws and predictions are easy given appropriate starting conditions. Perhaps, however, physicians coping with this uncertainty will perhaps feel more in tune with Heisenberg's uncertainty law. Heisenberg (1901–76) described a theory of quantum mechanics, published in 1925, when he was only 23 years old. The uncertainty principle describes an imprecision in nature resulting in a limit to what we can know about the behaviour of quantum particles and, hence the smallest scales of nature. Heisenberg was awarded the Nobel Prize for Physics for 1932 for this theory and its application that resulted amongst other things the discovery of allotropic forms of hydrogen. His theory stated that we cannot always give an electron a position in space at a given time, nor follow it in its orbit, so that we cannot assume that the planetary orbits proposed by Niels Bohr exist. Mechanical quantities, such as position and velocity, should be represented, not by ordinary numbers, but by abstract mathematical structures called ‘matrices’ and he formulated his new theory in terms of matrix equations. The principle of uncertainty, says that the determination of the position and momentum of a mobile particle necessarily contains errors the product of which cannot be less than the quantum constant h and that, although these errors are negligible on the human scale, they cannot be ignored in studies. We cannot measure the position (x) and the momentum (p) of a particle with absolute precision. The more accurately we know one of these values, the less accurately we know the other. There are many ways of looking at this and in medicine we need to take account of uncertainty. Uncertainty in medicine can be resolved in many ways and can include Occam's razor. In medicine, all presenting symptoms in a patient may be explained by a few possible causes. In medicine, all presenting symptoms in a patient may be due to several disease and social processes at the same time. How can this be relevant to a working physician? The whole of medical practice has parallels with the certainties of Newton and Bohr. The object of a clinical consultation is to give a sign or complaint a diagnostic named description to be followed by a treatment regime which resolves the problem. Yet every physician knows and automatically models his understanding of a clinical problem perhaps unknowingly on a model based on Heisenberg's uncertainty principle. A core process, which is complicated by factors understood or not. The same principles are relevant to so many other features of life. There are certain fixed points in the diagnostic and clinical process. Gender, race, age, weight to height ratio, privileged and social life and intelligence. Some people age at different rates to their age cohort? Similarly, obesity does not always matter. The patient′s family history is another variable, complicated occasionally when the putative father with a family health trait may not be the actual father. The social story is a minefield, with the possibility of every phase of a person’s life being of relevance. A further element is how well the physician and the patient and their caring team relate. The clinical examination then gives a further array of data. From all of this comes a diagnosis which gives a pathway to a treatment schedule the ability of the patient to manage their treatment regime becomes important. There is a tendency that as soon as the diagnosis is made then the other elements fade away from the care plan, though of course it persists in the person's life. We are all consciously or unconsciously aware of the complex fabric of clinical care. It is intriguing to appreciate that other disciplines have been presented with the same multifactorial uncertainties. The era in Physics when Heisenberg introduced his view of nuclear physics was one when a precise physical model was being completed and gave certainty to a complex problem. His principle while obviously reintroducing uncertainty gave freedom of thinking and allowed further fruitful progress. We physicians do not enjoy uncertainty, and to have it formalized is uncomfortable. So we instinctively identify the major problem and treat that. By and large this is a useful process. It is however important to see this as a convenience. A convenience that may not always suit the patient. Applying the Heisenberg principles gives a broader view of a patient's concerns and problems and better care.
The two most important areas in modern physics are quantum mechanics and the theory of relativity. Unlike classical physics, where Newton's mechanics dominates, these two areas change human beings' fundamental view of the universe. One of the theories that build up the base of quantum mechanics is Heisenberg's Uncertainty Principle. Starting from a thought experiment, Heisenberg's microscope in the setting of classical physics, Werner Heisenberg built a bridge between classical and quantum physics by presenting a counterintuitive outcome in the thought experiment. Since then, the observer of a physics phenomenon is no longer a bystander. The behavior of observation became a part of the physical experiment. To come up with a mathematical expression that can describe such a new discovery, Heisenberg came up with matrix mechanics and the concept of complementary variables. There is a trade-off between a pair of complementary variables. When one of them is measured precisely, meaning the information of that variable is known on a large scale, the other variable can not be measured precisely, meaning there is no way to know enough information about the other variable. The principle indicates a fundamental limit on what human beings can know about the unknown variables. The discoveries of other complementary variables help physicists know the new image of the physics world under new rules.
One of the most striking deviations of quantum mechanics from classical mechanics is that any measurement of a microscopic system involves the interaction with the measuring instruments. The interaction cannot be neglected and in fact leads to uncontrollable disturbance on the system. In 1927, Werner Karl Heisenberg in his celebrated paper established the quantitative expression for unavoidable momentum disturbance caused by any position measurement. The crucial word here is simultaneously. The uncertainty relation gives the lower bound on the product of the uncertainties of two pairs of variables. But it says nothing about the accuracy with which individual observables can be measured. The physical meaning of energy-time uncertainty is different from that of x-px uncertainty. Position and momentum are observables to which Hermitian operators are assigned and which are measured at a particular time. An important implication of the uncertainty principle is that quantum systems do follow classical trajectories which conflict with our everyday experience.
Abstract How certain is Heisenberg’s uncertainty principle? Heisenberg’s uncertainty principle is at the heart of the orthodox or Copenhagen interpretation of quantum mechanics. We first sketch the history that led up to the formulation of the principle. Then we recall that there are in fact two uncertainty principles, both dating from 1927, one by Werner Heisenberg and one by Earle Kennard. Finally, we explain that recent work in physics gives reason to believe that the principle of Heisenberg is invalid, while that of Kennard still stands.
Abstract Driven by the idea that a physical theory should only deal with observable quantities, Werner Heisenberg, a young post-doc working with Max Born in Göttingen, who had earlier done his Ph.D. work under Sommerfeld in Munich, was led to introduce a new type of object which represented the transitions between Bohr-Sommerfeld orbits. Max Born realized and recognized these objects as matrices. Together with Pascual Jordan, another post-doc, they worked out a complete theory, matrix mechanics. They completed this work in a few months. We discuss the role of matrix mechanics in the development of quantum mechanics.