The double slit interference and Davisson-Germer experiments.
In 1801 Thomas Young provided some very strong evidence to support the wave nature of light, he placed a monochromatic light in front of a screen with two slits cut into it, and observed an interference pattern, only possible if light was a wave. In 1965 Richard Feynman came up with a thought-experiment that was similar to Young’s experiment. In Feynman’s double-slit experiment, a chosen material is fired at a wall which has two small slits that can be opened and closed at will – some of the material gets blocked and some passes through the slits, depending on which ones are open.
Based on the pattern that is detected beyond the wall by a specific detector – one can distinguish whether the material coming through behaves as either a wave or particle.
When particles are fired at the wall with both slits open, they are more likely to hit the detector in one specific area, whereas waves interfere with each other creating an interference pattern.
Feynman proposed that electrons – historically thought to be particles – would actually produce the pattern of a wave in the double-split experiment.
Unlike water waves for example, Feynman emphasised that when electrons are fired through the slits one at a time, an interference pattern would be produced. He then famously said that this phenomenon “has in it the heart of quantum physics [but] in reality, it contains the only mystery.”
Finally in 2012 Feynman’s thought-experiment had been accurately carried out by a team of researchers. The team managed to “show a full realization of Feynman’s thought experiment and illustrate key features of quantum mechanics: interference and the wave-particle duality of matter.”
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...c energy of an accelerated electron, we get the equation:
1/λ = n/2dsinθ = p/h = (√2mE)/h = (√2meV)/h
Equation (1)
Davisson and Germer found that by varying the applied voltage to the electron gun, the maximum intensity of electrons diffracted by the atomic surface was found at different angles. The highest intensity was found to be at an angle θ = 50° with a voltage of 54 V, giving the electrons a kinetic energy of 54 eV.
According to the de Broglie relation and Bragg's law, a beam of 54 eV had a wavelength of 0.167 nm. The experimental outcome was 0.165 nm via the grating equation, which closely matched the predictions. Davisson and Germer's accidental discovery of the diffraction of electrons was the first direct evidence confirming de Broglie's hypothesis that particles can have wave properties as well.
through space. This theory came to life when Heinrich Hertz created those waves and seven
In 1906, a scientist by the name of Richard Dixon Oldham had suggested a theory structured another scientists findings by the name of Emil Wiechert. Oldham had identified that S waves and P waves behaved differently and
The cathode ray tube was invented in 1875 by the name of Sir Williams Crooke. Yet he wasn’t the one to make the big discovery. In 1897, a man by the name of J.J. Thompson conducted a series of experiments to prove the existence of subatomic particles. He wasn’t 100% correct with all of his claims he made but broke the theory John Dalton stated that the smallest form matter could be broken down to was an atom. Having shown the world that there was smaller than an atom, it later caused others to question and dive even deeper.
waves were reflected back to the transducer as they crossed interfaces of different acoustic impedance. More simply, the ultrasound bounced off the
The novel, Alice and Quantum Land, by Robert Gilmore is an adventure in the Quantum universe. Alice, a normal teenage girl, goes through quantum land and understands what quantum is and how it works. The quantum world is a difficult one to understand, as its nature is one of complex states of being, natures, principles, notions, and the like. When these principles or concepts are compared with the macro world, one can find great similarities and even greater dissimilarities between the world wherein electrons rule, and the world wherein human beings live. In Alice in Quantumland, author Robert Gilmore converts the original tale of Alice in Wonderland from a world of anthropomorphic creatures into the minute world of quantum mechanics, and attempts to ease the reader into this confusing world through a series of analogies (which comprise an allegory) about the principles of quantum mechanics. Through Alice’s adventure she comes across some ideas or features that contradict real world ideas. These ideas are the following: Electrons have no distinguishing spin, the Pauli Exclusion Principle, Superposition, Heisenberg Uncertainty Principle, and Interference and Wave Particle Duality.
Holtzman, Jack M. "A note on Schrodinger's cat and the unexpected hanging paradox." The British Journal for the Philosophy of Science v39. 1988. 397-401.
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Quantum Mechanics developed over many decades beginning as a set of controversial mathematical explanations of experiments that the math of classical mechanics could not explain. It began in the turn of the 20th century, a separate mathematical revolution in physics that describes the motion of things at high speeds. The origins of Quantum Mechanics cannot be credited to any one scientists. Multiple scientists contributed to a foundation of three revolutionary principles that gradually gained acceptance and experiment verification from 1900-1930 (Coolman). Quantum Mechanics is
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Matter is energy (Fernflores 1). The fact that electron-positron interactions can either produce photons or...
Some physical entities such as light can display some characteristics of both particles and waves. Before the early 20th century, scientists believed that light was in the form of an electromagnetic wave. It wasn’t until the 20th century onwards that scientists found that light has properties of waves and particles. Scientists discovered different properties of light through experimentation and allowed them to determine that light actually has a wave-particle duality.
The next big step in the discovery of the atom was the scientific test that proved the existence of the atom. After the discovery of the atom we had the discovery of subatomic particles. With the discovery of the subatomic particles came the research, which came from experiments that were made to find out more about the subatomic particles. This research is how we uncovered that most of the weight of an atom is from its nucleus. With the gold foil experiment, tested by Ernest Rutherford, he discovered the existence of the positively charged nucleus. He proved this when the experiment was happening, a small fraction of the photons th...
For instance, throughout the nineteenth century, it was correctly believed that light was a wave. If light were a wave like all other waves, it must have a medium through which to propagate through. This medium was called the ether, a substance which was everywhere throughout the universe. If this hypothesis were true one would be able to calculate the velocity of the Earth through the ether. Many experiments were conducted to determine this velocity the most famous one being the Michelson-Morley experiment.