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For centuries, the laws of physics seemed completely deterministic. If you knew where every particle was, how fast it was moving, and what the forces were between them at any one instant, you could know exactly where they\u2019d be and what they\u2019d be doing at any point in the future. From Newton to Maxwell, the rules that governed the Universe had no built-in, inherent uncertainty to them in any form. Your only limits arose from your limited knowledge, measurements, and calculational power.<\/p>\n
All of that changed a little over 100 years ago. From radioactivity to the photoelectric effect to the behavior of light when you passed it through a double slit, we began realizing that under many circumstances, we could only predict the probability that various outcomes would arise as a consequence of the quantum nature of our Universe. But along with this new, counterintuitive picture of reality, many myths and misconceptions have arisen. Here\u2019s the true science behind 10 of them.<\/p>\n
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By creating a track where the outside magnetic rails point in one direction and the inside magnetic rails point in the other, a Type II superconducting object will levitate, remain pinned above-or-below the track, and will move along it. This could, in principle, be scaled up to allow resistance-free motion on large scales if room-temperature superconductors are achieved.\n<\/p>\n
Credit<\/a>: Henry M\u00fchlpfordt\/TU Dresden\/Wikimedia Commons<\/p>\n 1.) Quantum effects only happen on small scales. When we think of quantum effects, we typically think about individual particles (or waves) and the bizarre properties they display. But large-scale, macroscopic effects happen that are inherently quantum in nature.<\/p>\n Conducting metals cooled below a certain temperature become superconductors: where their resistance drops to zero. Building superconducting tracks where magnets levitate above them and travel around them without ever slowing down\u00a0is a routine student science project<\/a>\u00a0these days, built on an inherently quantum effect.<\/p>\n Superfluids can be created on large, macroscopic scales, as can\u00a0quantum drums that simultaneously do and don\u2019t vibrate<\/a>. Over the past 25 years,\u00a06 Nobel Prizes have been awarded<\/a>\u00a0for various macroscopic quantum phenomena.<\/p>\n The differences in electron energy levels occur in all atoms, from the simplistic hydrogen to the most complex elements of all. This graph illustrates the energy level differences in an atom of Lutetium-177. Note how there are only specific, discrete energy levels that are acceptable. While the energy levels are discrete, the positions of the electrons are not.\n<\/p>\n Credit<\/a>: M.S. Litz and G. Merkel Army Research Laboratory, SEDD, DEPG<\/p>\n 2.) Quantum always means \u201cdiscrete.\u201d\u00a0The idea that you can chop up matter (or energy) into individual chunks\u200a\u2014\u200aor quanta\u200a\u2014\u200ais an important concept in physics, but it doesn\u2019t fully encompass what it means for something to be \u201cquantum\u201d in nature. For example: consider an atom. Atoms are made of atomic nuclei with electrons bound to them.<\/p>\n Now, think about this question: where is the electron at any moment in time?<\/p>\n Even though the electron is a quantum entity, its position is uncertain until you measure it. Take many atoms and bind them together (such as in a conductor), and you\u2019ll frequently discover that although there are discrete energy levels that the electrons occupy, their positions can literally be anywhere within the conductor. Many quantum effects are continuous in nature, and it\u2019s eminently possible that\u00a0space and time, at a fundamental, quantum level, are continuous<\/a>, too.<\/p>\n By creating two entangled photons from a pre-existing system and separating them by great distances, we can \u2018teleport\u2019 information about the state of one by measuring the state of the other, even from extraordinarily different locations. Interpretations of quantum physics that demand both locality and realism cannot account for a myriad of observations, but multiple interpretations all appear to be equally good.\n<\/p>\n Credit<\/a>: Melissa Meister\/ThorLabs<\/p>\n 3.) Quantum entanglement allows information to travel faster-than-light. Here\u2019s an experiment we can perform:<\/p>\n create two entangled particles,<\/p>\n separate them by a great distance,<\/p>\n measure certain quantum properties (like the spin) of one particle on your end,<\/p>\n and you can know some information about the quantum state of other particle instantaneously: faster than the speed of light.<\/p>\n But here\u2019s the thing about this experiment: no information is being transmitted faster than the speed of light. All that\u2019s happening is that by measuring the state of one particle, you are constraining the probable outcomes of the other particle. If someone goes and measures the other particle, they will have no way of knowing that the first particle has been measured and the entanglement has been broken. The only way to determine whether entanglement has been broken or not is to bring the results of both measurements back together again: a process that can only occur at light speed or slower.\u00a0No information can be passed faster than light<\/a>; this\u00a0was proven in a 1993 theorem<\/a>.<\/p>\n In a traditional Schrodinger\u2019s cat experiment, you do not know whether the outcome of a quantum decay has occurred, leading to the cat\u2019s demise or not. Inside the box, the cat will be either alive or dead, depending on whether a radioactive particle decayed or not. Although it\u2019s rarely discussed, the validity of a Schrodinger\u2019s cat experiment depends on the system being isolated from its environment; if the isolation isn\u2019t perfect, the quantum nature of the superposition-of-states will be disrupted.\n<\/p>\n Credit<\/a>: Dhatfield\/Wikimedia Commons<\/p>\n 4.) Superposition is fundamental to quantum physics. Imagine you have multiple possible quantum states that a system can be in. Maybe it can be in state \u201cA\u201d with 55% probability, state \u201cB\u201d with 30% probability, and state \u201cC\u201d with 15% probability. Whenever you go to make a measurement, however, you never see a mix of these possible states; you\u2019ll only get a single-state outcome: either it\u2019s \u201cA,\u201d \u201cB,\u201d or \u201cC.\u201d<\/p>\n Superpositions are incredibly useful as intermediate calculational steps to determine what your possible outcomes (and their probabilities) will be, but we can never measure them directly. In addition, superpositions don\u2019t apply to all measurables equally, as you can have a superposition of momenta but not positions or vice versa.\u00a0Unlike entanglement, which is a fundamental quantum phenomenon<\/a>, superposition is not quantifiably or universally measurable.<\/p>\n A variety of quantum interpretations and their differing assignments of a variety of properties. Despite their differences, there are no experiments known that can tell these various interpretations apart from one another, although certain interpretations, like those with local, real, deterministic hidden variables, can be ruled out.\n<\/p>\n Credit<\/a>: English Wikipedia page on Interpretations of Quantum Mechanics<\/p>\n 5.) There\u2019s nothing wrong with us all choosing our favorite quantum interpretation. Physics is all about what you can predict, observe, and measure in this Universe. Yet with quantum physics, there are multiple ways to conceive of what\u2019s occurring at a quantum level that all agree equally with experiments. Reality can be:<\/p>\n a series of quantum wavefunctions that instantaneously \u201ccollapse\u201d when a measurement is made,<\/p>\n an infinite ensemble of quantum waves, where a measurement selects one member of the ensemble,<\/p>\n a superposition of forward-moving and backward-moving potentials that meet in a \u201cquantum handshake,\u201d<\/p>\n an infinite number of possible worlds corresponding to the possible outcomes, where we simply occupy one path,<\/p>\n as well as many others. Yet\u00a0choosing one interpretation over another teaches us nothing<\/a>\u00a0except, perhaps, our own human biases. It\u2019s better to learn what we can observe and measure under various conditions, which is physically real, than to prefer an interpretation that has no experimental benefit over any other.<\/p>\n Many entanglement-based quantum networks across the world, including networks extending into space, are being developed to leverage the spooky phenomena of quantum teleportation, quantum repeaters and networks, and other practical aspects of quantum entanglement. The quantum state is \u201ccut-and-pasted\u201d from one location to another, but cannot be cloned, copied, or \u201cmoved\u201d without destroying the original state. In reality, no information is ever being exchanged faster than light.\n<\/p>\n Credit<\/a>: S.A. Hamilton et al., 70th International Astronautical Congress, 2019<\/p>\n 6.) Teleportation is possible, thanks to quantum mechanics. There actually is\u00a0a real phenomenon known as quantum teleportation<\/a>, but it most definitively does not mean that it\u2019s physically possible to teleport a physical object from one location to another. If you take two entangled particles and keep one close by while sending the other one to a desired destination, you can teleport the information from the unknown quantum state on one end to the other end.<\/p>\n This has enormous restrictions on it, however, including that it only works for single particles and that only information about an indeterminate quantum state, not any physical matter, can be teleported. Even if you could scale this up to transmit the quantum information that encodes an entire human being, transferring information is not the same as transferring matter: you cannot teleport a human, ever, with quantum teleportation.<\/p>\n This diagram illustrates the inherent uncertainty relation between position and momentum. When one is known more accurately, the other is inherently less able to be known accurately. Both position and momentum are better described by a probabilistic wavefunction than by a single value. Other pairs of conjugate variables, including energy and time, spin in two perpendicular directions, or angular position and angular momentum, also exhibit this same uncertainty relation.\n<\/p>\n Credit<\/a>: Maschen\/Wikimedia Commons<\/p>\n 7.) Everything is uncertain in a quantum Universe. Some things are uncertain, but many things are extremely well-defined and well-known in a quantum Universe. If you take an electron, for example, you cannot know:<\/p>\n its position and its momentum,<\/p>\n or its angular momentum in multiple, mutually perpendicular directions,<\/p>\n exactly and simultaneously under any circumstances. But some things about the electron can be known exactly! We can know its rest mass, its electric charge, or its lifetime (which appears to be infinite) with exact certainty.<\/p>\n The only things that are uncertain in quantum physics are pairs of physical quantities that have a specific relationship between them: that are\u00a0pairs of conjugate variables<\/a>. This is why there are uncertainty relations between energy and time, voltage and free charge, or angular momentum and angular position. While\u00a0many pairs of quantities have an inherent uncertainty<\/a>\u00a0between them, many quantities are still known exactly.<\/p>\n The inherent width, or half the width of the peak in the above image when you\u2019re halfway to the crest of the peak, is measured to be 2.5 GeV: an inherent uncertainty of about +\/- 3% of the total mass. The mass of the particle in question, the Z boson, is peaked at 91.187 GeV, but that mass is inherently uncertain by a significant amount owing to its excessively short lifetime. This result is remarkably consistent with Standard Model predictions.\n<\/p>\n Credit<\/a>: J. Schieck for the ATLAS Collaboration, JINST7, 2012<\/p>\n 8.) Every particle of the same type has the same mass. If you could take two identical particles\u200a\u2014\u200alike two protons or two electrons\u200a\u2014\u200aand put them on a perfectly accurate scale, they\u2019d always have the same exact mass as one another. But that\u2019s only because protons and electrons are stable particles with infinite lifetimes.<\/p>\n If you instead took unstable particles that decayed after a short while\u200a\u2014\u200asuch as two top quarks or two Higgs bosons\u200a\u2014\u200aand put them on a perfectly accurate scale, you wouldn\u2019t get the same values. This is because there\u2019s an inherent uncertainty between energy and time: if a particle only lives for a finite amount of time, then there\u2019s an inherent uncertainty in the amount of energy (and hence, from\u00a0E = mc\u00b2, rest mass) that the particle has. In particle physics, we call this a particle\u2019s \u201cwidth,\u201d and it can lead to a particle\u2019s inherent mass being uncertain by up to a few percent.<\/p>\n Niels Bohr and Albert Einstein, discussing a great many topics in the home of Paul Ehrenfest in 1925. The Bohr-Einstein debates were one of the most influential occurrences during the development of quantum mechanics. Today, Bohr is best known for his quantum contributions, but Einstein is better-known for his contributions to relativity and mass-energy equivalence. Both were known for thinking long and hard about the most difficult puzzles the Universe had to offer.\n<\/p>\n Credit<\/a>: Paul Ehrenfest<\/p>\n 9.) Einstein himself denied quantum mechanics. It\u2019s true that Einstein had a famous quote about how, \u201cGod does not play dice with the Universe.\u201d But arguing against a fundamental randomness inherent to quantum mechanics\u200a\u2014\u200awhich is what the context of that quote was about\u200a\u2014\u200ais arguing about how to interpret quantum mechanics, not an argument against quantum mechanics itself.<\/p>\n In fact, the nature of Einstein\u2019s argument was that there might be more to the Universe than we can presently observe, and if we could understand the rules we have not yet uncovered, perhaps what appears to be randomness to us here might reveal a deeper, non-random truth. Although this position has not yielded useful results, explorations of the fundamentals of quantum physics continues to be an active area of research, successfully ruling out a number of interpretations involving \u201chidden variables\u201d present in the Universe.<\/p>\n Today, Feynman diagrams are used in calculating every fundamental interaction spanning the strong, weak, and electromagnetic forces, including in high-energy and low-temperature\/condensed conditions. The electromagnetic interactions, shown here, are all governed by a single force-carrying particle: the photon, but weak, strong, and Higgs couplings can also occur.\n<\/p>\n Credit<\/a>: V. S. de Carvalho and H. Freire, Nucl. Phys. B, 2013<\/p>\n 10.)\u00a0Exchanges of particles in quantum field theory completely describe our Universe. This is the \u201cdirty little secret\u201d of quantum field theory that physicists learn in graduate school: the technique we most commonly use for calculating the interactions between any two quantum particles. We visualize them as particles being exchanged between those two quanta, along with all possible further exchanges that could occur as intermediate steps.<\/p>\n If you could extrapolate this to all possible interactions\u200a\u2014\u200ato what scientists call arbitrary\u00a0loop-orders<\/a>\u200a\u2014\u200ayou\u2019d wind up with nonsense. This technique is only an approximation: an\u00a0asymptotic, non-convergent series<\/a>\u00a0which breaks down past a certain number of terms. It\u2019s an incredibly useful picture in terms of its calculational power, but it has fundamental limits to its utility, and therefore, is fundamentally incomplete. The idea of \u201cvirtual particle exchanges\u201d mediating forces is compelling and intuitive, but is unlikely to provide the final answer.<\/p>\n This article was first published in December of 2022. It was updated in January of 2026.<\/p>\n \n Sign up for the Starts With a Bang newsletter <\/p>\n \n Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all. <\/p>\n","protected":false},"excerpt":{"rendered":"Sign up for the Starts With a Bang newsletter Travel the universe with Dr. Ethan Siegel as he…\n","protected":false},"author":2,"featured_media":382480,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[49],"tags":[199,79],"class_list":{"0":"post-382479","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-physics","9":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/382479","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=382479"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/382479\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/382480"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=382479"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=382479"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=382479"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/commons.wikimedia.org\/wiki\/File:Stickstoff_gek%C3%BChlter_Supraleiter_schwebt_%C3%BCber_Dauermagneten_2009-06-21.jpg\")
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