The Quantum World Is Lumpy
The quantum world has a lot in common with shoes. You cant just go to a shop and pick out sneakers that are an exact match for your feet. Instead, youre forced to choose between pairs that come in predetermined sizes.
The subatomic world is similar. Albert Einstein won a Nobel Prize for proving that energy is quantized. Just as you can only buy shoes in multiples of half a size, so energy only comes in multiples of the same “quanta” hence the name quantum physics.
The quanta here is the Planck constant, named after Max Planck, the godfather of quantum physics. He was trying to solve a problem with our understanding of hot objects like the sun. Our best theories couldnt match the observations of the energy they kick out. By proposing that energy is quantized, he was able to bring theory neatly into line with experiment.
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 SchrÃ¶dinger 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.
How Is Quantum Mechanics Different From Classical Physics
At the scale of atoms and electrons, many of the equations of classical mechanics, which describe the movement and interactions of things at everyday sizes and speeds, cease to be useful.
In classical mechanics, objects exist in a specific place at a specific time. In quantum mechanics, objects instead exist in a haze of probability they have a certain chance of being at point A, another chance of being at point B and so on.
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Examples Of Quantum In A Sentence
quantumquantum Forbesquantum Scientific Americanquantum Forbesquantum National Reviewquantum WSJquantum New York Timesquantum BostonGlobe.comquantum Ars Technicaquantum Popular Mechanicsquantum Quanta Magazinequantum BGRquantum Scientific Americanquantum WSJquantum Fortunequantum New York Timesquantum Popular Mechanics
These example sentences are selected automatically from various online news sources to reflect current usage of the word ‘quantum.’ Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
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 .
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Are Quantum Mechanics And General Relativity Incompatible
At the moment, physicists lack a full explanation for all observed particles and forces in the universe, which is often called a theory of everything. Einstein’s relativity describes large and massive things, while quantum mechanics describes small and insubstantial things. The two theories are not exactly incompatible, but nobody knows how to make them fit together.
Many researchers have sought a theory of quantum gravity, which would introduce gravity into quantum mechanics and explain everything from the subatomic to the supergalactic realms. There are a great deal of proposals for how to do this, such as inventing a hypothetical quantum particle for gravity called the graviton, but so far, no single theory has been able to fit all observations of objects in our universe. Another popular proposal, string theory, which posits that the most fundamental entities are tiny strings vibrating in many dimensions, has started to become less widely accepted by physicists since little evidence in its favor has been discovered. Other researchers have also worked on theories involving loop quantum gravity, in which both time and space come in discrete, tiny chunks, but so far no one idea has managed to gain a major hold among the physics community.
This article was originally written by Live Science contributor Robert Coolman and was updated by Adam Mann on March 2, 2022.
Why Is Probability Important In Quantum Physics
One more thing. That theres a 50 percent probability that a tossed coin will land heads simply means that it has two sides and we have no way of knowing which way up it will land. This is a classical probability born of ignorance.
We can be confident that the coin continues to have two sides heads and tails as it spins through the air, but were ignorant of the exact details of its motion so we cant predict with certainty which side will land face up. In theory, we could, if we knew exactly how hard you flipped it at exactly what angle, and at exactly what height you would catch it.
Quantum probability is thought to be very different. When we toss a quantum coin we might actually be quite knowledgeable about most of the details of its motion, but we cant assume that heads and tails exist before the coin has landed, and we look.
So, it doesnt matter exactly how much information you have about the coin toss, you will never be able to say with any certainty what the result will be, because its not pre-determined like in a classical system.
Einstein deplored this seeming element of pure chance in quantum mechanics. He famously declared that: God does not play dice.
And then, in 1927, the debates began. What is the wave function and how should it be interpreted? What is quantum mechanics telling us about the nature of physical reality? And just what is this thing called reality, anyway?
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Quantum Mysticism And Media
I think it is best to start by stating what quantum is not. First of all, quantum is always a verb or and adjective. If you hear someone saying something like the quantum, they probably dont understand it or you could even be facing a snake oil vendor.
Yes, I understand the word sometimes stands, in the media that deals with communication of science, for some otherwordly results. Even in more reputable newspapers and journals it is often somewhat fictionalized as a transcendent new area, which is too much for our minds to fathom. Why? Well, clickbait of course! Dont get me wrong, I believe it is breathtakingly interesting, sometimes confusing, and definitely worth exploring. However, in my opinion, this approach tends to shut people out of the beautiful ideas in Quantum Mechanics. It unjustly transforms it into a hermetic secret, only available to a few enlightened. And this cant be more wrong. For example, I see many concepts from quantum mechanics in articles in the news and even in memes which are used out of context, at best, and straight up misrepresented, at worst. The first one that comes to my mind, and probably yours too, is the famous Schrödingers cat. To try to disentangle all this, I want to explain a couple of things first.
Multiple Splits Multiple Worlds
Even to seasoned scientists, its odd to think that the universe splits apart depending on whether a molecule bounces this way or that way. Its odder still to realize that a similar splitting could occur for every interaction taking place in the quantum world.
Things get downright bizarre when you realize that all those subatomic splits would also apply to bigger things, including ourselves. Maybe theres a world in which a version of you split off and bought a winning lottery ticket. Or maybe in another, you tripped at the top of a cliff and fell to your death oops.
It’s absolutely possible that there are multiple worlds where you made different decisions. We’re just obeying the laws of physics, says Sean Carroll, a theoretical physicist at the California Institute of Technology and the author of a new book on many worlds titled “Something Deeply Hidden.” Just how many versions of you might there be? We don’t know whether the number of worlds is finite or infinite, but it’s certainly a very large number,” Carroll says. “Theres no way its, like, five.
Carroll is aware that the many worlds interpretation sounds like something plucked from a science fiction movie. And like a Hollywood blockbuster, the many worlds interpretation attracts both passionate fans and scathing critics.
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Types Of Quantum Physics
A representation of an atom.
Although it is a study that deals with minuscule particles, there are three main theories that deal with different types of forces. These are not branches of this subject as such. Even though gravity is one of the strong forces of nature, it only applies to object of a certain size, and in quantum mechanics, it just doesnt function.
- Electromagnetism: It is basically a study that focuses on the charge of bodies. It consists of two main components, electricity and magnetism. In the past, these two were considered as separate forces, however, as our understanding of physics expanding we found them to be one, thanks to Albert Einsteins theory of relativity, though they do behave differently. When it comes to quantum mechanics, it explains how atoms are held together and continue to remain that way.
- Weak Nuclear Force: Finally, the last and the weirdest force among all. This explains the radioactive decay of an atom. Also, it should be noted that weak nuclear force has a preference for the spin of the particles and whether they are matter or anti-matter. It is an extremely weak force compared to the other ones.
Quantum physics deals with an extremely weird plane of existence. Whatever we know as accepted physics, all just disqualifies when going to that extreme level. As a former science student, it is both intriguing and complicated to wrap my head around. It is the type of study we should leave for experts.
What Does Quantum Physics Mean To You
By | Submitted On March 17, 2010
The main thing you have to know about Quantum physics is when the electrons are not watched, they behave like a wave showing wave interference patterns. When the electrons are watched they turn into actual particles of matter and show the single line patterns you would expect for shooting particles through slits. What does it mean? Here is how we are going to interpret it. Get ready…
Nothing is separate. The entire universe, including you and I, are in reality pure energy. It is through our thoughts that we transform this energy into what we perceive to be reality. Remember in the video, the waves became particles when watched. Our thoughts create the world we live in. The paradigm shift is we have always thought the outer world is more real than the inner world. But the opposite is true. It is what is happening inside us that determines what is going to happen outside us. We create our world with our thoughts.
Now ask yourself this question. What does it mean for energy to play the piano, play the guitar, sing, speak French or program a computer? In our three dimensional world we use our conscious mind to perceive the energy as its physical counterpart. This to us becomes playing the piano, playing the guitar, etc… The energy that becomes every single thing in the universe is us. Which means it can’t be partial to any single one individual. If one person can do it so can you.
How do we do that?
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The History Of Quantum Mechanics
We now know that all matter is composed of atoms. Each atom is in turn made up of electrons orbiting a nucleus consisting of protons and neutrons. Atoms are discrete. They are localised: here or there.
But towards the end of the 19th Century, atoms were really rather controversial. In fact, it was a determination to refute the existence of atoms that led the German physicist Max Planck to study the properties and behaviour of so-called black-body radiation.
What he found in an act of desperation in late-1900 turned him into a committed atomist, but it took a few more years for the real significance of his discovery to sink in.
Planck had concluded that radiation is absorbed and emitted as though it is composed of discrete bits which he called quanta. In 1905, Albert Einstein went further. He speculated that the quanta are real radiation itself comes in discrete lumps of light-energy. Today we call these lumps .
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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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How Did We Get Here
The mind-bending saga of the many worlds interpretation began in 1926, when Austrian physicist Erwin Schrödinger mathematically demonstrated that the subatomic world is fundamentally blurry.
In the familiar, human-scale reality, an object exists in one well-defined place: Place your phone on your bedside table, and thats the only spot it can be, whether or not you’re looking for it. But in the quantum realm, objects exist in a smudge of probability, snapping into focus only when observed.
Before you look at an object, whether it’s an electron, or an atom or whatever, it’s not in any definite location, Carroll says. It might be more likely that you observe it in one place or another, but it’s not actually located at any particular place.
Nearly a century of experimentation has confirmed that, strange as it seems, this phenomenon is a core aspect of the physical world. Even Einstein struggled with the notion: What happened to all of the other possible locations where the object could have been, and all the other different outcomes that could have ensued? Why should an objects behavior depend on whether or not somebody was looking at it?
A Particle Is A Quantum Excitation Of A Field2
The picture soon got even stranger. In the 1930s, physicists realized that the wave functions of many individual photons collectively behave like a single wave propagating through conjoined electric and magnetic fields exactly the classical picture of light discovered in the 19th century by James Clerk Maxwell. These researchers found that they could quantize classical field theory, restricting fields so that they could only oscillate in discrete amounts known as the quanta of the fields. In addition to photons the quanta of light Paul Dirac and others discovered that the idea could be extrapolated to electrons and everything else: According to quantum field theory, particles are excitations of quantum fields that fill all of space.
In positing the existence of these more fundamental fields, quantum field theory stripped particles of status, characterizing them as mere bits of energy that set fields sloshing. Yet despite the ontological baggage of omnipresent fields, quantum field theory became the lingua franca of particle physics because it allows researchers to calculate with extreme precision what happens when particles interact particle interactions being, at base level, the way the world is put together.
An irreducible representation of the Poincaré group, a precocious classmate answered.
Elementary particles with one and five spin labels also appear in nature. Only a representation of the Poincaré group with four spin labels seems to be missing.
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