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Validity of the quantum world - why Schrödinger's cat belongs to us

The quantum world, how we know it, is very different from our world what we are experiencing. The quantum world is fuzzy and probabilisti...

The quantum world, how we know it, is very different from our world what we are experiencing. The quantum world is fuzzy and probabilistic, a real contrast with our world which is concrete and deterministic. However, where is the border between the two worlds? Where is the end of our "normal" world, and where does the quantum world start, when we become smaller and smaller? Is the border sharp or fuzzy between the two? Schrödinger's cat belongs to the quantum or she is a member of the world what we are experiencing? Or belongs to both? Can we answer this question?

The quantum world is fuzzy and probabilistic because it built on a kind of wave existence.  We are giving a probabilistic meaning to the wave-behavior in quantum mechanics because when the quantum world collides and creates our world, we can give meaning to our experiments by the probability of the results of these collisions. However, deep down, the quantum world behaves, as it would be waves. Therefore, where does the quantum world starts, and where does our deterministic world cease to exist? The quantum world is where the wave behavior is the law. The quantum world is the world, where these waves, the quantum states, are the rule, even if they create complex structures. If the waves are overlapping and are synchronized with each other, there is where the quantum world exists.

How big the quantum world can be? The border between the two worlds is not determined by a given size but determined by the size of the wave and the size of the construction of the waves, the size of the waves, which are synchronized to each other. Its typical size ends where the atoms or molecules end. What about a big and complex molecule? The whole molecule belongs to the quantum world or belongs to our deterministic world? It depends on the quantum waves, and how these waves are overlapped and synchronized. Parts of the molecule can behave quantum-mechanically, but when its two ends collide, it may behave classically.

So typically, the quantum world is small. However, the quantum world can be even as big as a superconducting magnet. Maybe even, it can be in cosmic size, maybe even the whole universe was in a quantum state once where all quantum states were overlapped and synchronized. In addition, maybe the universe will be in this overlapping and synchronized quantum state sometime again.

Our world is not in this state now, it is not in an overlapping and synchronized quantum state of quantum states, but in the states of different quantum states, which exist independently, and occasionally collide with each other and create our deterministic world. This way we can draw a line between the quantum world and our everyday world.

So is Schrödinger's cat dead or alive? Or both? She is in one state because she belongs to our world; she is dead or alive, but not both. The quantum states of the cat and the quantum state of the decaying nucleus are not overlapping and not synchronized to each other. The box - with them - is not in one quantum state. As Schrödinger would say: it is ridiculous.

Moreover, how is our deterministic world created from the probabilistic quantum world? It is the same question as to the measurement problem in quantum theory. The measurement problem is the almost philosophical question of, how we are doing experiments with the quantum world, how it becomes concrete to us. In these experiments, in most cases, what we see and how we define, the wave function collapses. It means that the fuzzy quantum state takes a value, which the value still probabilistic and looks random, but it becomes a concrete value then. What happens when we perform a measurement? Or - by equivalently to the measurement - what happens when independently existing quantum states collide with each other? Our deterministic world is born in this process. But how?

There are philosophical approaches to this question. They say, the measurement creates our world, or maybe our conscious recognition creates our world. In a more realistic approach, the measurement actually a record of value, the realized parameter of a collapsed quantum state, this got its value in the moment of the recording. And this record can be made by any kind of interaction, and it is made every time when the interaction occurs. This approach eliminates the necessity of consciousness but still assumes the existence of a kind of memory, the memory of the records.

The measurement problem is not really the problem of the measurement. Of course, we can get knowledge about the quantum world only when we are performing measurements, but the problem is rooted not in our subjective experience, not even in our objectively existing memory. The measurement problem is the problem of the interaction, the interaction between independently existing quantum states. The measurement takes place when quantum worlds collide.

What happens when two, independently existing quantum worlds collide? Both are different quantum worlds with independently synchronized quantum states. As the interaction occurs, both quantum states change, and this sharp change what we can read as a value, and as we define it, it is the collapse of the wave-function. After the collapse, both parts have a new quantum state, the so-called collapse is just a moment of the change of the quantum states.

When we are doing the double-slit experiment with an electron, until we are not interacting with the electron, the electron is in a quantum equilibrium, behaves as a wave. The wave can travel through both slits (if its size is comparable to the wavelength of the electron) and interfere with themselves, as the waves do, and creates a trajectory, which - if many recorded - shows us the interference pattern. Because the electron does not interact with the matter what the physical slit was built from, they do not change each other's quantum states; the electron-wave is not disturbed. However, if we modify this experiment and we interact with the electron-wave when it travels between the slits, the wave changes its quantum state, the wave of the electron "collapses", the wave gets its value at the location where the interaction occurs, the electron "appears" at the exact place, and we experience the physical existence of the electron. After the interaction, from the place where it occurs, a new wave starts, a new quantum state of the electron becomes to existence. This wave is not capable to interact with itself because it is not traveling through both slits anymore, thus it will not create the interference pattern. When and where the interaction occurs, there is the electron in full existence, it "materialize itself" at that moment. And our world, what we know, is born.

The grid model may give a view of what the physical background of this wave-particle behavior is. The grid model was discussed in several thoughts.

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