1. Schrödinger’s cat
As stated by the Copenhagen interpretation, the state of the system and its position relative to other states can only be determined by an observation (the wave function is used only to help mathematically calculate the probability of the system being in one state or another). We can say that after observation, the quantum system becomes classical and immediately cease to exist in other states, except for the state it has been observed.
This approach has always had its opponents (remember for example Albert Einstein’s “God does not play dice“), but the accuracy of the calculations and predictions prevailed. However, the number of supporters of the Copenhagen interpretation is decreasing and the major reason for that is the mysterious instant collapse of the wave function during the experiments. The famous mental experiment by Erwin Schrödinger with the poor cat was meant to demonstrate the absurdity of this phenomenon.
Let us recap the nature of this experiment. A live cat is placed inside a black box, together with a vial containing poison and a mechanism that can release this poison at random. For instance, a radioactive atom during its decay can break the vial. The precise time of atom’s decay is unknown. Only half-life, or the time during which the decay occurs with a probability of 50%, is known.
In fact, until the observer opens the box, the cat will be subjected to the endless balance on the brink of being between life and death, and its fate can only be determined by the action of the observer. That is the absurdity pointed out by Schrödinger .
2. Diffraction of electrons
There is a source that emits a stream of electrons onto photosensitive screen. And there is obstruction in the way of these electrons, a copper plate with two slits. What kind of picture can be expected on the screen if the electrons are imagined as small charged balls? Two strips illuminated opposite to the slits.
In fact, the screen displays a much more complex pattern of alternating black and white stripes. This is due to the fact that, when passing through the slit, electrons begin to behave not as particles, but as waves (just like the photons, or light particles, which can be waves at the same time). These waves interact in space, either quenching or amplifying each other, and as a result, a complex pattern of alternating light and dark stripes appears on the screen.
Electrons seemed not wanting to show their wave nature under the watchful eye of observers. Did they manage to follow their instinctive desire to see a clear and simple picture. Is this some kind of a mystery? There is a more simple explanation: no observation of a system can be carried out without physically impacting it. But we will discuss this a bit later.
3. Heated fullerene
Recently, a group of scientists from the University of Vienna supervised by Professor Zeilinger tried to introduce an element of observation in these experiments. To do this, they irradiated moving fullerene molecules with a laser beam. Then, warmed by an external source, the molecules began to glow and inevitably displayed their presence in space to the observer.
Together with this innovation, the behavior of molecules has also changed. Prior to the beginning of such comprehensive surveillance, fullerenes quite successfully avoided obstacles (exhibited wave-like properties) similar to the previous example with electrons passing through an opaque screen. But later, with the presence of an observer, fullerenes began to behave as completely law-abiding physical particles.
4. Cooling measurement
Recent experiments by Professor Schwab in the U.S. are even more valuable in this respect, where quantum effects have been demonstrated not at the level of electrons or fullerene molecules (their characteristic diameter is about 1 nm), but on a little more tangible object, a tiny aluminum strip.
This strip was fixed on both sides so that its middle was in a suspended state and it could vibrate under external influence. In addition, a device capable of accurately recording strip’s position was placed near it.
As a result, the experimenters came up with two interesting findings. First, any measurement related to the position of the object and observations of the strip did affect it, after each measurement the position of the strip changed. Generally speaking , the experimenters determined the coordinates of the strip with high precision and thus , according to the Heisenberg’s principle, changed its velocity, and hence the subsequent position.
Secondly, which was quite unexpected, some measurements also led to cooling of the strip. So, the observer can change physical characteristics of objects just by being present there.
5. Freezing particles
This quantum effect was first predicted back in the 1960s, and its brilliant experimental proof appeared in the article published in 2006 by the group led by Nobel laureate in Physics Wolfgang Ketterle of the Massachusetts Institute of Technology.
In this paper, the decay of unstable excited rubidium atoms was studied (photons can decay to rubidium atoms in their basic state). Immediately after preparation of the system, excitation of atoms was observed by exposing it to a laser beam. The observation was conducted in two modes: continuous (the system was constantly exposed to small light pulses) and pulse-like (the system was irradiated from time to time with more powerful pulses).
The obtained results are perfectly in line with theoretical predictions. External light effects slow down the decay of particles, returning them to their original state, which is far from the state of decay. The magnitude of this effect for the two studied modes also coincides with the predictions. The maximum life of unstable excited rubidium atoms was extended up to 30-fold.
Quantum mechanics and consciousness
We are only one step away from admitting that the world around us is just an illusory product of our mind. Scary, isn’t it? Let us then again try to appeal to physicists. Especially when in recent years, they favor less the Copenhagen interpretation of quantum mechanics, with its mysterious collapse of the wave function, giving place to another quite down to earth and reliable term decoherence.
Here’s the thing, in all these experiments with the observations, the experimenters inevitably impacted the system. They lit it with a laser and installed measuring devices. But this is a common and very important principle:you cannot observe the system or measure its properties without interacting with it. And where there is interaction, there will be modification of properties. Especially when a tiny quantum system is impacted by colossal quantum objects. So the eternal Buddhist observer neutrality is impossible.
This is explained by the term “decoherence”, which is an irreversible, from the point of view of thermodynamics, process of altering the quantum properties of the system when it interacts with another larger system. During this interaction the quantum system loses its original properties and becomes a classic one while “obeying ” the large system. This explains the paradox of Schrödinger’s cat: the cat is such a large system that it simply cannot be isolated from the rest of the world. The mere design of this mental experiment is not quite correct.
In any event, compared to the reality of consciousness as an act of creation, decoherence represents a much more convenient approach. Perhaps even too convenient. Indeed, with this approach, the entire classical world becomes one big consequence of decoherence. And as the authors of one of the most prominent books in this field stated, such an approach would also logically lead to statements like “there are no particles in the world” or ” there is no time on a fundamental level”.
Is it the creator-observer or powerful decoherence? We have to choose between the two evils. But remember, now scientists are increasingly convinced that the basis of our mental processes is created by these notorious quantum effects. So, where the observation ends and reality begins, is up to each of us.