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Authors: James Kakalios
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Planck’s constant, h, is a unit of angular momentum. When Planck introduced the constant h as a fudge to account for the spectrum of light emitted by hot, glowing objects, he had hit upon a fundamental constant of the universe. There is a set of basic numbers that one must specify when setting up a universe, such as the mass of the electron and the speed of light. Things would look very different if the speed of light, for example, was a value a person could achieve while riding a bicycle, such as 15 miles per hour. One would then have an intimate, firsthand intuition about the consequences of the Special Theory of Relativity. Similarly, if Planck’s constant were a much larger number, we would have to deal with quantum phenomena in our daily lives.
In Isaac Asimov’s novel Fantastic Voyage II: Destination Brain, a team of scientists is reduced in size, smaller than a single cell, in order to travel within the body of an injured scientist (who has figured out a way to make miniaturization energy efficient!) and perform an operation. Asimov proposes that the mechanism underlying this shrinking process involves creating a field that reduces the magnitude of Planck’s constant. Considering an atom to be a sphere, Bohr calculated its radius to be a few times r o , where r o = h / [(2π)m e c α] and m e is the mass of the electron, c is the speed of light, and α is termed “the fine structure constant” that involves another collection of fundamental constants (such as h, c, and the charge of the electron). If one could tune Planck’s constant at will, making it larger or smaller, then one could enlarge or shrink any object by changing the fundamental size of its atoms. 16 The fact that we cannot do this in reality reflects the fact that fundamental constants are just that—constant and unchanging.
It was unnerving to physicists when Albert Einstein suggested in 1905 that there was no velocity faster than light speed, but the universe and its laws indeed ensure that nothing can move faster than the speed of light in a vacuum. Apparently, with the discovery that subatomic particles have internal angular momentums whose values are multiples of either h /2π or 1/2 of h /2π but not any other values, the universe also cares about rotation.
The electron is the basic unit of negative charge, while the proton has an equal charge, but of an opposite sign (by convention the proton’s charge is termed “positive” while the electron’s is “negative”). It has been known since the 1820s that moving electric charges, that is, an electrical current, create a magnetic field. This is the basic physical principle underlying electromagnets and motors. If an electrically charged sphere rotates about a line passing through its center, like a wheel about its center spoke, then there are certainly electrical charges in motion, and these currents will generate a magnetic field. If there is an intrinsic angular momentum, it shouldn’t be surprising that as a consequence of this rotation every electron and proton has its own internal magnetic field. In fact, the quantized internal angular momentum aspect was proposed to account for the experimentally observed internal magnetic fields inside atoms. That is, the observation of the magnetic field came first, and later, in an attempt to account for it, the argument about intrinsic angular momentum was put forward.
Does the experimentally observed magnetic field of electrons and protons actually arise from the spinning rotation of elementary particles? Technically, the answer is no. The simplest reason why not is that neutrons, the other fundamental particle found within atomic nuclei, which have nearly the same mass as protons but are electrically uncharged, also possesses an internal magnetic field! If the magnetic field of the proton arose from the fact that as a charged object, its rotation could be described as a series of electrical current loops, each of which generates a
In Isaac Asimov’s novel Fantastic Voyage II: Destination Brain, a team of scientists is reduced in size, smaller than a single cell, in order to travel within the body of an injured scientist (who has figured out a way to make miniaturization energy efficient!) and perform an operation. Asimov proposes that the mechanism underlying this shrinking process involves creating a field that reduces the magnitude of Planck’s constant. Considering an atom to be a sphere, Bohr calculated its radius to be a few times r o , where r o = h / [(2π)m e c α] and m e is the mass of the electron, c is the speed of light, and α is termed “the fine structure constant” that involves another collection of fundamental constants (such as h, c, and the charge of the electron). If one could tune Planck’s constant at will, making it larger or smaller, then one could enlarge or shrink any object by changing the fundamental size of its atoms. 16 The fact that we cannot do this in reality reflects the fact that fundamental constants are just that—constant and unchanging.
It was unnerving to physicists when Albert Einstein suggested in 1905 that there was no velocity faster than light speed, but the universe and its laws indeed ensure that nothing can move faster than the speed of light in a vacuum. Apparently, with the discovery that subatomic particles have internal angular momentums whose values are multiples of either h /2π or 1/2 of h /2π but not any other values, the universe also cares about rotation.
The electron is the basic unit of negative charge, while the proton has an equal charge, but of an opposite sign (by convention the proton’s charge is termed “positive” while the electron’s is “negative”). It has been known since the 1820s that moving electric charges, that is, an electrical current, create a magnetic field. This is the basic physical principle underlying electromagnets and motors. If an electrically charged sphere rotates about a line passing through its center, like a wheel about its center spoke, then there are certainly electrical charges in motion, and these currents will generate a magnetic field. If there is an intrinsic angular momentum, it shouldn’t be surprising that as a consequence of this rotation every electron and proton has its own internal magnetic field. In fact, the quantized internal angular momentum aspect was proposed to account for the experimentally observed internal magnetic fields inside atoms. That is, the observation of the magnetic field came first, and later, in an attempt to account for it, the argument about intrinsic angular momentum was put forward.
Does the experimentally observed magnetic field of electrons and protons actually arise from the spinning rotation of elementary particles? Technically, the answer is no. The simplest reason why not is that neutrons, the other fundamental particle found within atomic nuclei, which have nearly the same mass as protons but are electrically uncharged, also possesses an internal magnetic field! If the magnetic field of the proton arose from the fact that as a charged object, its rotation could be described as a series of electrical current loops, each of which generates a
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