Without It The Sun Wouldnt Shine
The sun makes its energy through a process called nuclear fusion. It involves two protons the positively charged particles in an atom sticking together. However, their identical charges make them repel each other, just like two north poles of a magnet. Physicists call this the Coulomb barrier, and its like a wall between the two protons.
Think of protons as particles and they just collide with the wall and move apart: No fusion, no sunlight. Yet think of them as waves, and its a different story. When the waves crest reaches the wall, the leading edge has already made it through. The waves height represents where the proton is most likely to be. So although it is unlikely to be where the leading edge is, it is there sometimes. Its as if the proton has burrowed through the barrier, and fusion occurs. Physicists call this effect “quantum tunneling”.
Relation To General Relativity
Even though the predictions of both quantum theory and general relativity have been supported by rigorous and repeated empirical evidence, their abstract formalisms contradict each other and they have proven extremely difficult to incorporate into one consistent, cohesive model. Gravity is negligible in many areas of particle physics, so that unification between general relativity and quantum mechanics is not an urgent issue in those particular applications. However, the lack of a correct theory of quantum gravity is an important issue in physical cosmology and the search by physicists for an elegant “Theory of Everything” . Consequently, resolving the inconsistencies between both theories has been a major goal of 20th- and 21st-century physics. This TOE would combine not only the models of subatomic physics but also derive the four fundamental forces of nature from a single force or phenomenon.
Another popular theory is loop quantum gravity , which describes quantum properties of gravity and is thus a theory of quantum spacetime. LQG is an attempt to merge and adapt standard quantum mechanics and standard general relativity. This theory describes space as an extremely fine fabric “woven” of finite loops called spin networks. The evolution of a spin network over time is called a spin foam. The characteristic length scale of a spin foam is the Planck length, approximately 1.616Ã10â35 m, and so lengths shorter than the Planck length are not physically meaningful in LQG.
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Although they might be found anywhere, the certainty of finding one of these particles in any particular place is zero. Scientists can predict where they might be yet they never know where they are.
The bottom line is, the quantum world just doesnt work in the way the world around us works, says David Lindley. We dont really have the concepts to deal with it, he says. Trained as a physicist, Lindley now writes books about science from his home in Virginia.
Heres a taste of that weirdness: If you hit a baseball over a pond, it sails through the air to land on the other shore. If you drop a baseball in a pond, waves ripple away in growing circles. Those waves eventually reach the other side. In both cases, something travels from one place to another. But the baseball and the waves move differently. A baseball doesnt ripple or form peaks and valleys as it travels from one place to the next. Waves do.
But in experiments, particles in the subatomic world sometimes travel like waves. And they sometimes travel like particles. Why the tiniest laws of nature work that way isnt clear to anyone.
Do you really believe the moon exists only when you look at it? Albert Einstein famously asked.
A quantum recipe
Quantum theory thrills scientists even as it frustrates them.
Is the cat okay?
New York Times
Welcome to the multiverse
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Is Light A Wave Or A Particle
Einsteins hypothesis posed a bit of a problem. There was an already well-established body of evidence in favour of a wave theory of light. The key observation is called the double slit experiment.
Push light through a narrow aperture or slit and it will squeeze through, bend around at the edges and spread out beyond. It diffracts.
Cut two slits side-by-side and we get interference. Waves diffracted by the two slits produce an alternating pattern of light and dark bands called interference fringes. This kind of behaviour is not limited to light such wave interference is easily demonstrated using water waves.
But waves are inherently delocalised: they are here and there. Einsteins hypothesis didnt overturn all the evidence for the delocalised wave-like properties of light. What he was suggesting is that a complete description somehow needs to take account of its localised, particle-like properties, too.
So, light acts like both a wave and a particle.
In 1923, French physicist Louis de Broglie made a bold suggestion. If light waves can also be particles, could particles like electrons also be waves? This was just an idea, but he was able to use it to develop a direct mathematical relationship between an electrons wave-like property and a particle-like property .
Application To The Bohr Model
De Broglie expanded the Bohr model of the atom by showing that an electron in orbit around a nucleus could be thought of as having wave-like properties. In particular, an electron is observed only in situations that permit a standing wave around a nucleus. An example of a standing wave is a violin string, which is fixed at both ends and can be made to vibrate. The waves created by a stringed instrument appear to oscillate in place, moving from crest to trough in an up-and-down motion. The wavelength of a standing wave is related to the length of the vibrating object and the boundary conditions. For example, because the violin string is fixed at both ends, it can carry standing waves of wavelengths 2 n }} , where l is the length and n is a positive integer. De Broglie suggested that the allowed electron orbits were those for which the circumference of the orbit would be an integer number of wavelengths. The electron’s wavelength, therefore, determines that only Bohr orbits of certain distances from the nucleus are possible. In turn, at any distance from the nucleus smaller than a certain value, it would be impossible to establish an orbit. The minimum possible distance from the nucleus is called the Bohr radius.
De Broglie’s treatment of quantum events served as a starting point for Schrödinger when he set out to construct a wave equation to describe quantum-theoretical events.
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Development Of Modern Quantum Mechanics
In 1925, Werner Heisenberg attempted to solve one of the problems that the Bohr model left unanswered, explaining the intensities of the different lines in the hydrogen emission spectrum. Through a series of mathematical analogies, he wrote out the quantum-mechanical analog for the classical computation of intensities. Shortly afterward, Heisenberg’s colleague Max Born realized that Heisenberg’s method of calculating the probabilities for transitions between the different energy levels could best be expressed by using the mathematical concept of matrices.
In the same year, building on de Broglie’s hypothesis, Erwin Schrödinger developed the equation that describes the behavior of a quantum-mechanical wave. The mathematical model, called the Schrödinger equation after its creator, is central to quantum mechanics, defines the permitted stationary states of a quantum system, and describes how the quantum state of a physical system changes in time. The wave itself is described by a mathematical function known as a “wave function“. Schrödinger said that the wave function provides the “means for predicting the probability of measurement results”.
Schrödinger was able to calculate the energy levels of hydrogen by treating a hydrogen atom’s electron as a classical wave, moving in a well of the electrical potential created by the proton. This calculation accurately reproduced the energy levels of the Bohr model.
What Does Quantum Physics Actually Tell Us About The World
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The Unfinished Quest for the Meaning of Quantum PhysicsBy Adam Becker 370 pp. Basic Books. $32.
Are atoms real? Of course they are. Everybody believes in atoms, even people who dont believe in evolution or climate change. If we didnt have atoms, how could we have atomic bombs? But you cant see an atom directly. And even though atoms were first conceived and named by ancient Greeks, it was not until the last century that they achieved the status of actual physical entities real as apples, real as the moon.
The first proof of atoms came from 26-year-old Albert Einstein in 1905, the same year he proposed his theory of special relativity. Before that, the atom served as an increasingly useful hypothetical construct. At the same time, Einstein defined a new entity: a particle of light, the light quantum, now called the photon. Until then, everyone considered light to be a kind of wave. It didnt bother Einstein that no one could observe this new thing. It is the theory which decides what we can observe, he said.
Figuring out what quantum physics is saying about the world has been hard, Becker says, and this understatement motivates his book, a thorough, illuminating exploration of the most consequential controversy raging in modern science.
This is disturbing to philosophers as well as physicists. It led Einstein to say in 1952, The theory reminds me a little of the system of delusions of an exceedingly intelligent paranoiac.
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Mathematics And The Probabilistic Nature Of Quantum Objects
Because many of the concepts of quantum physics are difficult if not impossible for us to visualize, mathematics is essential to the field. Equations are used to describe or help predict quantum objects and phenomena in ways that are more exact than what our imaginations can conjure.
Mathematics is also necessary to represent the probabilistic nature of quantum phenomena. For example, the position of an electron may not be known exactly. Instead, it may be described as being in a range of possible locations , with each location associated with a probability of finding the electron there.
Given their probabilistic nature, quantum objects are often described using mathematical “wave functions,” which are solutions to what is known as the Schrödinger equation. Waves in water can be characterized by the changing height of the water as the wave moves past a set point. Similarly, sound waves can be characterized by the changing compression or expansion of air molecules as they move past a point. Wave functions don’t track with a physical property in this way. The solutions to the wave functions provide the likelihoods of where an observer might find a particular object over a range of potential options. However, just as a ripple in a pond or a note played on a trumpet are spread out and not confined to one location, quantum objects can also be in multiple placesâand take on different states, as in the case of superpositionâat once.
No Matter How Hard Physicists Probe They Still Puzzle Over This The Universe’s Deepest Secret
The quantum world is the world thats smaller than an atom. Things at this scale dont behave the same way as objects on the scale that we can see.
If youre interested in the smallest things known to scientists, theres something you should know. They are extraordinarily ill-behaved. But thats to be expected. Their home is the quantum world.
Explainer: Quantum is the world of the super small
These subatomic bits of matter dont follow the same rules as objects that we can see, feel or hold. These entities are ghostly and strange. Sometimes, they behave like clumps of matter. Think of them as subatomic baseballs. They also can spread out as waves, like ripples on a pond.
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Free Online Book Audio Download What Is Real: The Unfinished Quest For The Meaning Of Quantum Physics By Adam Becker In English
“A thorough, illuminating exploration of the most consequential controversy raging in modern science.” New York Times Book Review Every physicist agrees quantum mechanics is among humanity’s finest scientific achievements. But ask what it means, and the result will be a brawl. For a century, most physicists have followed Niels Bohr’s solipsistic and poorly reasoned Copenhagen interpretation. Indeed, questioning it has long meant professional ruin, yet some daring physicists, such as John Bell, David Bohm, and Hugh Everett, persisted in seeking the true meaning of quantum mechanics. What Is Real? is the gripping story of this battle of ideas and the courageous scientists who dared to stand up for truth. “An excellent, accessible account.” Wall Street Journal “Splendid. . . . Deeply detailed research, accompanied by charming anecdotes about the scientists.” Washington Post
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Quantum Physics For Regular People: Is Reality Even Real
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Tristan covers human-centric artificial intelligence advances, quantum computing, STEM, Voltron, physics, and space stuff. Pronouns: He/him Tristan covers human-centric artificial intelligence advances, quantum computing, STEM, Voltron, physics, and space stuff. Pronouns: He/him
Everything you assume about the universe, the laws that govern it, and how objective reality works is probably wrong. What goes up doesnt have to come down, theres no logical reason why we cant travel through time, and theres a pretty good chance that you exist as one of an infinite number of doppelgangers spread across parallel universes.
Thats not stoner logic or the use of science fiction as a proxy for real science those are actually just a few fairly tame interpretations of quantum mechanics.
Quantum mechanics is a unified theory that sets out to bridge the differences between classical physics , and quantum physics . Scientists have spent the past century or so trying to figure out why the two worlds dont seem to jive when it comes to what reality really is.
Quantum mechanics doesnt care much for time. Depending on how you interpret the scientific findings and empirical evidence that quantum mechanics is built on, time is a very fluid construct. Because subatomic particles dont just act like regular objects they also act like waves we cant make the same determinations about objects over time at the quantum scale that we do at the classical.
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What Is The Schrdinger’s Cat Paradox
Schrödinger’s cat is an often-misunderstood thought experiment describing the qualms that some of the early developers of quantum mechanics had with its results. While Bohr and many of his students believed that quantum mechanics suggested that particles don’t have well-defined properties until they are observed, Schrödinger and Einstein were unable to believe such a possibility because it would lead to ridiculous conclusions about the nature of reality. In 1935, Schrödinger proposed an experiment in which the life or death of a cat would depend on the random flip of a quantum particle, whose state would remain unseen until a box was opened. Schrödinger hoped to show the absurdity of Bohr’s ideas with a real-world example that depended on the probabilistic nature of a quantum particle but yielded a nonsensical result.
According to Bohr’s interpretation of quantum mechanics, until the box was opened, the cat existed in the impossible dual position of being both alive and dead at the same time. Both Schrödinger and Einstein believed that this helped show that quantum mechanics was an incomplete theory and would eventually be superseded by one that accorded with ordinary experience.
Entanglement has been shown to be one of the most essential aspects of quantum mechanics and occurs in the real world all the time. Researchers frequently conduct experiments using quantum entanglement and the phenomenon is part of the basis for the emerging field of quantum computing.
John Bell First Encountered The Mathematics Of Quantum Physics As A
The people of Tlön are taught that the act of counting modifies theamountcounted,turningindefinitesintodefinites.Thefactthatseveralpersonscountingthesamequantitycometothesameresultisforthepsychologists of Tlön an example of the association of ideas or ofmemorization. JorgeLuisBorges,Tlön,Uqbar,OrbusTertius
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What Does Quantum Theory Actually Tell Us About Reality
Nearly a century after its founding, physicists and philosophers still dont knowbut theyre working on it
For a demonstration that overturned the great Isaac Newtons ideas about the nature of light, it was staggeringly simple. It may be repeated with great ease, wherever the sun shines, the English physicist Thomas Young told the members of the Royal Society in London in November 1803, describing what is now known as a double-slit experiment, and Young wasnt being overly melodramatic. He had come up with an elegant and decidedly homespun experiment to show lights wavelike nature, and in doing so refuted Newtons theory that light is made of corpuscles, or particles.
But the birth of quantum physics in the early 1900s made it clear that light is made of tiny, indivisible units, or quanta, of energy, which we call photons. Youngs experiment, when done with single photons or even single particles of matter, such as electrons and neutrons, is a conundrum to behold, raising fundamental questions about the very nature of reality. Some have even used it to argue that the quantum world is influenced by human consciousness, giving our minds an agency and a place in the ontology of the universe. But does the simple experiment really make such a case?
But theres only one photon going through the apparatus at any one time. Its as if each photon is going through both slits at once and interfering with itself. This doesnt make classical sense.