Paradoxical effects, ghostly effects at a distance and all sorts of mysterious things: the bizarre phenomena of the quantum world are the focus of the September issue of Bild der Wissenschaft. The intellectual “impositions” of quantum physics are still causing researchers a lot of headaches and possible explanations are being hotly debated. The proposed solutions are sometimes astonishing and seem to contradict the human perception of reality, as the cover story shows.
The predictable if-then relationships and other rules of classical physics do not seem to apply in the quantum world: the behavior of waves and matter in the size range of atoms appears strangely nonlocal, random and superimposed. This leads to paradoxical effects, spooky actions at a distance and bizarre random phenomena. These phenomena have remained difficult to explain to this day, although quantum theory is the focus of many research teams worldwide and has already led to countless technical applications. The strange predictions are not just pure theory either – they have also been partially confirmed experimentally. Nevertheless, some aspects of the models appear inconsistent – some are still unresolved, incomplete or contradictory.
In the first article of the three-part cover story, bdw editor Rüdiger Vaas first explains which aspects of the quantum world are so confusing and how they caused headaches for the pioneers of the research field, Albert Einstein, Max Planck and Erwin Schrödinger. He then focuses on the concept of matter waves, which goes back to the physicist Louis de Broglie. It states that, depending on which experiments are carried out or which type of interaction is being considered, both matter and radiation can appear either as particles or as waves. This view has not changed to this day. But questions still remain unanswered and consequences arise that seem difficult to reconcile with the human perception of reality.
Decoherence and quantum collapse
In the quantum realm, seemingly paradoxical superposition states occur. This is illustrated by the famous thought experiment of Schrödinger’s cat: The animal would have to be everywhere at the same time and simultaneously alive and dead – until an observation reveals exactly where and in what state the cat is. In the article “Schrödinger’s ghostly cat”, Vaas explains why these ghostly quantum superpositions and the role of chance and discontinuity represent downright impositions of the quantum world on the human mind.
The second article is mainly about an effect that can explain at least some strange aspects of the quantum world: Vaas reports on decoherence. The phenomenon provides clues as to why superpositions are only measured under isolated conditions, but do not appear in everyday life. The effect can even be quantified and recorded with sophisticated experiments. Nevertheless, the picture still appears bizarre: spooky long-distance effects shift the quantum interference into the wider environment, thereby removing it from our observation. But the decoherence effect at least partially sheds light on the central mystery of quantum physics, explains Vaas in the article “How our classical world is created”.
The cover story is rounded off by an article that makes it clear that the “unreasonableness” of quantum physics does not only affect the microcosm: the focus is on physicists’ search for the limits of the quantum world. It is becoming apparent that the findings on the decoherence effect only shift the problematic aspects. Perhaps the entire universe is in superposition. In the article “Controversial Collapse”, Vaas explains why models that postulate a spontaneous quantum collapse can shed light on some unclear aspects of quantum physics, but again raise difficult questions and further problems.
You can read the articles on the cover story “Why the quantum world is so strange” online as part of a bdw+ subscription, or you can find them in the September issue of bild der wissenschaft, which will be available in stores from August 16.