Last week Ruth & I went for a scan at Queen Elizabeth Hospital and were faced with the marvellous image of our very own kicking, 5cm long baby who at one point turned to face us in response to the ultrasound waves. Obviously we're both delighted and petrified all at once, immersed in all the life-changing potentialities of the human + human = human equation. But the laws of reproduction and other processes taking place around us only apply to our immediate physical world, while an entirely different set of rules applies to the world of the very small (atomic) and the very large (cosmic). Here, I'm taking a trip to the micro world to try and understand the ideas of various scientists including Niels Bohr, the father of quantum physics.
20th century science has shed light on the quantum world and its various quirks, helping us understand various processes such as radioactivity and interference fringes (the interaction of particle waves); basically, how light and particles behave. At the heart of this weird world is a system of correlations completely different to those in the classical world, i.e. ours. For instance, quantum particles can appear in two different places at the same time, disappear altogether or act differently when we observe them. Two key questions are, where is the interface between these micro and macro worlds, and how do we sort out the problem of measuring phenomena given this paradoxical situation?
The Schroedinger’s Cat experiment highlights the measurement problem in quantum physics, by revealing the paradox of applying quantum laws to everyday objects, in this case a cat, a flask of poison and a geiger counter, all of which are sealed in a box, resulting in the cat being both alive and dead at the same time. Yet, from physical experience, we’re sure this isn’t possible. This is because at the atomic level, the laws of Newtonian mechanics break down, and vice versa.
One way of mapping the behaviour of particles in quantum physics is the wave function – a complex mathematical algorithm used to calculate the probability a particle is found in a certain location, or certain state of motion. However, if this process is observed or measured, wave function collapse occurs and the particle is reduced to being located in only one of those probable states. This is known as the Copenhagen interpretation.
However, eminent physicist Niels Bohr rejected the wave function as a mere mathematical algorithm that is not applicable to quantum physics, and this idea has recently gained currency among the physics community. Some modern experiments still suggest that the wave function is in fact “real”, but questions remain about how applicable it is to the macro or classical world. Physicists of a more philosophical bent see this debate in terms of an “epistemological” problem – the difference between an object viewed from the outside and “of and in itself”.
Again, this relates to the uncertainty principle and the fact that measurements using instruments are just approximations of the appearance of an unknowable essence. Like judging the mood of a friend based on their smiling face, even though they may be sad inside. In quantum mechanics, for example, the location of a particle can be measured but not its momentum, and vice versa.
For physicists, the holy grail remains finding a way of relating gravity to quantum physics, and this would also solve the measurement problem. Some physicists even see a need to go back to the root and branch of the science, formulated by Newton and Einstein, and start again to find a solution. However, any revolution in physics would require new anomalies and phenomena, and this can only be brought about by the mass displacement experiments in places like CERN; the first results from the Large Hadron Collider are expected after July this year.
20th century science has shed light on the quantum world and its various quirks, helping us understand various processes such as radioactivity and interference fringes (the interaction of particle waves); basically, how light and particles behave. At the heart of this weird world is a system of correlations completely different to those in the classical world, i.e. ours. For instance, quantum particles can appear in two different places at the same time, disappear altogether or act differently when we observe them. Two key questions are, where is the interface between these micro and macro worlds, and how do we sort out the problem of measuring phenomena given this paradoxical situation?
The Schroedinger’s Cat experiment highlights the measurement problem in quantum physics, by revealing the paradox of applying quantum laws to everyday objects, in this case a cat, a flask of poison and a geiger counter, all of which are sealed in a box, resulting in the cat being both alive and dead at the same time. Yet, from physical experience, we’re sure this isn’t possible. This is because at the atomic level, the laws of Newtonian mechanics break down, and vice versa.
One way of mapping the behaviour of particles in quantum physics is the wave function – a complex mathematical algorithm used to calculate the probability a particle is found in a certain location, or certain state of motion. However, if this process is observed or measured, wave function collapse occurs and the particle is reduced to being located in only one of those probable states. This is known as the Copenhagen interpretation.
However, eminent physicist Niels Bohr rejected the wave function as a mere mathematical algorithm that is not applicable to quantum physics, and this idea has recently gained currency among the physics community. Some modern experiments still suggest that the wave function is in fact “real”, but questions remain about how applicable it is to the macro or classical world. Physicists of a more philosophical bent see this debate in terms of an “epistemological” problem – the difference between an object viewed from the outside and “of and in itself”.
Again, this relates to the uncertainty principle and the fact that measurements using instruments are just approximations of the appearance of an unknowable essence. Like judging the mood of a friend based on their smiling face, even though they may be sad inside. In quantum mechanics, for example, the location of a particle can be measured but not its momentum, and vice versa.
For physicists, the holy grail remains finding a way of relating gravity to quantum physics, and this would also solve the measurement problem. Some physicists even see a need to go back to the root and branch of the science, formulated by Newton and Einstein, and start again to find a solution. However, any revolution in physics would require new anomalies and phenomena, and this can only be brought about by the mass displacement experiments in places like CERN; the first results from the Large Hadron Collider are expected after July this year.
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