The concept you're referring to is known as the observer effect or the measurement problem in quantum physics. It is related to the behavior of particles at the quantum level and the role of observation in determining their properties.
In quantum mechanics, particles can exist in what is called a superposition, where they can simultaneously be in multiple states or locations. However, when a measurement or observation is made on a quantum system, its wavefunction "collapses" into a single state or location corresponding to the observed property.
The observer effect does not imply that something does not exist unless it is observed in the conventional sense. It means that the properties of a quantum system are not definite or fixed until they are measured. Prior to measurement, a particle can exist in a superposition of states, but once observed, it appears in a specific state.
It's important to note that the observer effect applies to quantum systems and is not directly applicable to macroscopic objects like chocolate cakes. The behavior of everyday objects is well-described by classical physics, where observation does not have the same fundamental impact as it does at the quantum level.
In the case of a chocolate cake, the act of observing it does not fundamentally alter its existence or properties. If you observe a chocolate cake and it does not appear, it is likely due to other factors such as the absence of a cake, an illusion, or a perceptual error rather than a direct consequence of the observer effect in quantum mechanics.
Quantum mechanics is a complex and counterintuitive theory that describes the behavior of particles at the smallest scales. While the observer effect is a fascinating aspect of quantum physics, its implications are primarily relevant to the behavior of particles in controlled experimental setups, rather than everyday observations of macroscopic objects.