Quantum theory predicts the motion and behavior of particles at the atomic and subatomic level.
The term quantum mechanics (QM) generally refers to a mathematical formulation of quantum theory. It often describes and predicts the motion and behavior of particles at the atomic and subatomic level. This includes particles such as atoms, electrons, protons, and photons. According to QM, the behavior and movement of particles at these microscopic levels is counterintuitive, radically different from anything observed in everyday life. This requires a theory like quantum mechanics to better explain this different world.
In the macroscopic world, there are generally two types of phenomena that are classified by scientists: particles and waves. The particles can be seen as localized, carrying mass and energy in their movements. Waves are a type of phenomenon that are never localized and have no mass, but carry energy. The microworld particles examined in quantum mechanics are different from those of the macroworld, because in certain situations, particles can act like waves, whereas, conversely, waves can act like particles. According to QM, this would mean that, at the quantum level, an apple could behave like a wave, while a wave could behave like an apple.
Quantum mechanics uses the quantum unit to roughly assign and measure quantities of the physical properties of these particles. Particles are generally measured by considering the wave function recorded at the time of measurement. However, since particles can behave like waves, the simultaneous location or speed of a particle can never be fully determined.
This apparent conundrum is known as Heisenburg’s uncertainty principle, which in other words states that position and momentum cannot be accurately measured simultaneously. This is not just because there are limitations in equipment or measurement capabilities, but because this uncertainty is believed to be inherent in the particles themselves. Quantum mechanics, therefore, is a mathematical theory that tries to calculate probabilities as a function of the wave function.
Many scientists do not agree with the postulates of QM. Albert Einstein was a scientist who sometimes criticized quantum theory as it conflicted with his own theory. Thus, one of the biggest problems in contemporary physics is to create a theory that unifies the ideas of quantum mechanics with those of Einstein’s general theory of relativity. Physicists such as Julian Barbour have proposed some innovative solutions to this problem, basically stating that if we humans consider that time itself does not exist, there is no obstacle to unifying quantum mechanics and the theory of relativity.