r/QuantumPhysics • u/outofplace_2015 • 21h ago
What is a lesser-known quantum phenomenon OR quantum theory you wish more people knew about?
Its quantum physics so the stranger the better.
r/QuantumPhysics • u/theodysseytheodicy • Apr 29 '25
Late 19th c. through Schrödinger and Dirac
Quantum physics is usually taught to advanced physics undergraduates, but to work through most of the thought experiments and most quantum algorithms, you only need linear algebra. If you really want to understand the physics, though, you'll need multivariable calculus, differential equations, classical mechanics, and electromagnetism (see "Theoretical minimum" above).
A complex vector space is a set (whose elements are the points of the space, called "vectors") equipped with a way to add vectors together and a way to multiply vectors by a complex number. A Hilbert space is a complex vector space where you can measure the angle between two vectors. The state of a generic quantum system is a vector called a "wave function" with length 1 in a Hilbert space.
So roughly, a quantum state can be written as a list of complex numbers whose magnitudes squared add up to 1. The list is indexed by possible classical outcomes. Physical processes are represented by unitary matrices, matrices X such that the conjugate transpose of X is the inverse of X. Things you can measure are represented by Hermitian matrices, matrices equal to their conjugate transpose.
What's written in the previous paragraph is all true for finite-dimensional Hilbert spaces, spaces that represent quantum states with a finite number of possible classical outcomes. If there are infinitely many possible outcomes—for example, when measuring the position of an electron in a wire, the answer is a real number—then we have to generalize a little. A list of n complex numbers can be represented as a function from the set {0, 1, ..., n-1} of indices to the set of complex numbers. Similarly, we can represent infinite-dimensional quantum states like the position of an electron in a wire as functions from the real numbers ℝ to the complex numbers ℂ. Instead of summing the magnitudes squared, we integrate, and instead of using matrices, we use linear transformations.
Superposition is the fact that you can add or subtract two vectors and get another vector. This is a feature of any linear wavelike medium, like sound. In sound, superposition is the fact that you can hear many things at once. In music, superposition is chords. Superposition is also a feature of the space we live in: we can add north and east to get northeast. We can also subtract east from north and get northwest.
Entanglement is a particular kind of superposition; see below.
The Born postulate says that the probability you see some outcome X is the square of the magnitude of the complex number at position X in the list. For infinite-dimensional spaces, we have to integrate over some region to get a complex number; so, for example, we can find the probability that an electron is in some portion of a wire, but the probability of being exactly at some real coordinate is infinitesimal.
The inner product of two vectors tells you what the angle is between the two. If you prepare a quantum state X and then measure it, the probability of getting some classical outcome Y is the cosine of the angle between X and Y squared. So if X is parallel to Y, you'll always see Y, and if X is perpendicular to Y, you'll never see Y. If X is somewhere in between, you'll sometimes see Y at a rate given by the inner product.
We write the inner product of X and Y as <X|Y>. This is "bracket notation", where <X| is a "bra" and |Y> is a "ket". When we're working with a finite-dimensional Hilbert space, |Y> denotes a column vector, <X| denotes a row vector, and <X|Y> is the complex number we get by multiplying the two. The real part of the inner product is proportional to the cosine of the angle between them:
Re(<X|Y>) = ‖X‖ ‖Y‖ cos θ.
Given a vector
|A> = |a₁|
|a₂|
|⋮ |
|aₙ|
and a vector
|B> = |b₁|
|b₂|
|⋮ |
|bₘ|
representing the states of two quantum systems that have never interacted, the composite system is represented by the vector
|A>⊗|B> = |a₁·b₁|
|a₁·b₂|
| ⋮ |
|a₁·bₘ|
|a₂·b₁|
|a₂·b₂|
| ⋮ |
|a₂·bₘ|
| ⋮ |
| ⋮ |
|aₙ·b₁|
|aₙ·b₂|
| ⋮ |
|aₙ·bₘ|.
This vector is called the Kronecker product of A and B.
An entangled state is any vector that can't be written as the Kronecker product of two others. For example, if
|A> = |a₁|
|a₂|
and
|B> = |b₁|
|b₂|,
then
|A>⊗|B> = |a₁b₁|
|a₁b₂|
|a₂b₁|
|a₂b₂|.
The vector
|C> = |1/√2|
| 0 |
| 0 |
|1/√2|.
can't be written this way. Suppose it could: since a₁b₂ = 0, then either a₁ is 0 or b₂ is 0. But a₁b₁ is not 0, so a₁ can't be 0, and a₂b₂ is not 0, so b₂ can't be 0. Therefore, there's no way to write the combined quantum system |C> as the product of two independent parts. To reason about |C>, you have to think about both qubits together.
Almost every interaction ends up entangling the two particles (or three, if it's a decay). Equilibrium for a quantum system is completely entangled. The hard part of doing quantum experiments is preventing particles from getting entangled with each other and the environment.
See also superposition
But why does entanglement break once you measure one part of it?
If you start with particle A being entangled with particle B, and then you have a measurement device undergo a unitary interaction with particle A so that the measurement device becomes correlated with particle B, then what happens is that the entanglement spreads to the whole combined measurement-device/particle-A/particle-B system, and none of the entanglement remains in the smaller particle-A/particle-B subsystem.
For photons
For delayed choice (tbd)
For delayed choice eraser (tbd)
With full explanation (Roger Bach et al 2013 New J. Phys. 15 033018)
See this comment.
No. If Alice and Bob each have half of an entangled pair of qubits, there is no operation Alice can perform on her qubit that Bob could detect by examining his qubit. It is only when they communicate at the speed of light that they discover that their measurement results are correlated.
There is a lot of confusion on this matter, and it is often depicted wrong in science fiction, so it bears repeating. Entanglement is not Twin Telepathy. There is absolutely nothing that you can do to one particle in an entangled pair that results in anything measurable happening to the other particle. It's true that if you prepare a pair in the state (|00> + |11>)/√2 and you measure the state of one of them, you know the state of the other. But there's no way to detect if a particle is in such a state unless you have access to both particles. Flipping one of the particles doesn't cause the other to flip. Measuring one of them doesn't make anything detectable happen to the other.
Classically, we can prepare correlated states. I can put each glove from a pair into two packages, randomly send you one and keep the other. That's a probabilistic mixture (|RL><RL| + |LR><LR|)/2. When I open my box and see which glove I have, I learn what glove you have. But in this scenario, there is hidden information: one of the gloves was always the left and the other was always the right.
Entangled states are similar, but they're quantum superpositions of correlated states. Suppose I have two qubits in the |00> state. By applying a Hadamard to the first, a control-NOT from the first to the second, and a NOT to the first, I get the state (|01> + |10>)/√2, which is a maximally entangled state. If I measure the first qubit, I learn the value of the second. But in the standard interpretation of quantum mechanics, there's no hidden information. The state of the first qubit wasn't defined before measuring it.
Other interpretations approach this differently.
But all of them obey the same math, and that math does not allow FTL communication.
Spin is a kind of angular momentum that fundamental particles have. It doesn't have a classical analogue.
It is an intrinsic property of elementary particles on one hand, and a quantized observable which behaves like the angular momentum from classical mechanics on the other. Similarly to how mass is the energy associated to some particles just by their existence, spin is the angular momentum associated to some particles just by their existence. And just as there are massless particles like photons, there are spin-0 particles like the Higgs boson. In this sense, it is "something real and measurable, just like mass and charge".
Spin is the name of one of the quantum numbers in the mathematical formalism of quantum mechanics. In this sense, it is "just something that comes out from the mathematical description".
A key feature of spin is that its magnitude can take on values of s = (n-1)/2 where n can be any positive integer, so n = 1, 2, 3, 4, 5, ... s = 0, 1/2, 1, 3/2, 2, ... Particles with integer spin are called bosons, whereas particles with half-integer spin are called fermions.
Subreddit/crowdsourced answers
In order to make a measurement, we need a quantum system X to be measured and a quantum system Y ("the observer") to serve as the record of the measurement. The measurement itself is any physical process that makes the state of Y depend on X. If the state of X is not an eigenstate of the observable, the resulting combined system X ⊗ Y will be entangled.
An observer is any quantum system separate from the system being observed that becomes entangled with it during the measurement process. An observer can be as small or as large as you like, from an electron to a human, to a galactic cluster. See this comment for an analysis of the double slit experiment with a single qutrit as the observer.
A wave function is a function from classical configurations to complex numbers. You can think of it as an infinite list of complex numbers, where the index into the list is given by the configuration. The Schrödinger equation describes a single spinless particle, where a configuration is an element of ℝ³, a set of coordinates for the particle.
As humans, we never perceive superpositions of matter waves. There are lots of different ideas about why that should be. One of the oldest, called "the Copenhagen interpretation" after a conference where lots of famous physicists met to talk about quantum physics, is that somehow when we measure a quantum system, the wave function undergoes a sudden, discontinuous change. There are many problems with this idea. "If it worked the way its adherents say it does, it would be:
However suggestive this may appear, these points are subject to critical evaluation.
The Nobel laureate Roger Penrose had an idea that perhaps wave functions collapse due to differences in the curvature of spacetime, but that was recently disproven.
There are lots of ideas about what's going on at the quantum level. These are called "interpretations" of quantum mechanics.
Stapp is a prominent proponent of the consiousness-is-collapse idea. He postulates, based on human experience, that free will exists. However, since the Schrödinger equation is deterministic and random wave collapse is not choice, he says there's a third process, specifically for free will, and that this is the root of consciousness. This third process is a form of postselection on human brain states. Some kooks have taken Wigner and Stapp's ideas and claim that humans can postselect the universe to get money and sex. If unrestricted postselection is possible, it not only grants the ability to solve NP-complete problems in polynomial time (last two paragraphs, page 19), but also the ability to collapse the galaxy into a black hole. (Greg Egan's novel Quarantine, which Aaronson cites, is a story about what the universe would be like if such postselection were possible.) Stapp suggests perhaps this third process is limited in a way that makes it useless for computation and effects outside a mind.
The punchline of The Talk is, "If you don't talk to your kids about quantum computing, someone else will," with a magazine saying, "Quantum computing and consciousness are both weird and therefore equivalent."
Decoherence is when a quantum system becomes entangled with its environment and stops being able to display constructive and destructive interference.
See this response.
There are four fundamental constants that form the basis of Planck units:
These can be combined in different ways to get different fundamental units: charge, length, mass, temperature, and time.
The Planck length is √(ℏG/c³) = 1.616255(18)×10−35 m. A proton is about 10−15 m, so if you could scale up a proton to a meter in diameter and then zoom in again by the same amount (making the proton about the size of the Oort cloud, tens of thousands of times the distance from the sun to earth), a Planck length would still only be around a tenth of a millimeter.
The Planck length is the scale where we know quantum field theory breaks down and we'll need a theory of quantum gravity to accurately predict what's going on there.
Quantum mechanics is a nonrelativistic theory. The number of particles is conserved. There's a quantum analogue to a mass on a spring called a quantum harmonic oscillator (QHO). In a classical harmonic oscillator, the system can have any energy. In a quantum harmonic oscillator, it can only have certain energies, just like a guitar string of a fixed length has certain frequencies it vibrates at. The difference between these energy levels is called a "quantum of energy".
Quantum field theory (QFT) assigns a QHO to each point in spacetime [well, really to each point in "energy-momentum space", with coordinates (E, px, py, pz) and QHO natural frequency E/ℏ]; you can think of it as a universal springy mattress. QFT then adds interaction terms between the QHOs, called "propagators". A particle is then similar to a wave pulse you get when you shake or "excite" the mattress. The propagators are "Lorentz invariant", so they work well with special relativity.
See this comment
QFT is quantum theory combined with special relativity. Quantum gravity is the unsolved problem of combining quantum theory with general relativity, which includes gravity and curved spacetime. String theory is one attempt to combine the two, and suggests that instead of being pointlike (0-dimensional), particles are 1-dimensional objects called "strings". It predicts that every particle we've seen has a heavier "supersymmetric" twin "sparticle". A lot of beautiful mathematics has come out of string theory, but none of its predictions have been verified yet. Physicists hoped the sparticles would be within reach of smaller particle colliders due to a "naturality" argument, but with the failure of the LHC to find any, there's no reason to think we'll see them in larger colliders.
Loop quantum gravity is the most popular alternative, but it hasn't made testable predictions yet, either. There are a lot of less popular alternatives, too.
In a quantum harmonic oscillator, the lowest energy level isn't zero, it's ℏω/2. If you integrate over more than a single point in momentum space, you get infinity for the ground state.
Quantum electrodynamics (QED) is "renormalizable": there's a mathematical trick that Tomonaga, Schwinger, and Feynman worked out for getting rid of the infinity. It involves taking a sum of a bunch of terms (corresponding to Feynman diagrams with more and more vertices) and pushing the infinity to later and later terms. But it only works because the fine structure constant is unitless, so we only need a single measurement for the first term and we can derive the others.
The "Lagrangian" for a system is the difference between kinetic and potential energy. If you integrate the Lagrangian with respect to time, you get a quantity with units of "action". Classically, systems take the path of least action. Quantum mechanically, the system takes all paths weighted by a phase exp(iS), where S is the action of the path. Paths far from the path of least action tend to cancel out: given any path p with action much greater than the least-action path, there's a path p' with smaller action whose phase is minus one times the phase of p, so they add up to zero.
There's a Lagrangian formulation of general relativity, but instead of being unitless like the fine structure constant, the coupling constant has units of inverse mass. If we try to do the renormalization trick in the same way we did for QED, we would need to make a new measurement for each of the infinitely many correction terms.
It's designing a system where quantum states constructively interfere to produce the right answer. SMBC's "The Talk" is an astonishingly good introduction.
That's only part of how quantum algorithms work. You can certainly put a quantum computer into a uniform superposition of inputs and test each of them. But now you've got a big superposition
∑ |input, whether correct>
and if you measure it, you'll just get the answer to whether a random input was correct, which isn't what you want. Quantum algorithms have to make use of some structure of the problem to make the wrong answers less probable and the right answer more probable.
There are two main quantum algorithms applicable to cryptography, Grover's algorithm and Shor's algorithm. Grover's algorithm effectively cuts the size of a symmetric key in half: if you have a 128-bit key, it'll take 264 iterations to find it. It also reduces the difficulty of finding a collision in an n-bit hash function from 2n/2 to 2n/3. Shor's algorithm breaks public key algorithms like RSA and ECC that depend on the difficulty of the hidden subgroup problem.
Bitcoin uses secp256k1 as its public key algorithm, an elliptic curve-based signature algorithm. To claim someone's bitcoin, you effectively have to figure out their private key given their public key. A quantum computer that could keep thousands of bits coherent forever could break Bitcoin quickly using Shor's algorithm.
This article estimates that it will take until the late 2030s/early 2040s to get there at the current exponential rate of growth.
Wikipedia's explanation is very good.
Quanta magazine has a great explanatory article.
Almost everything you see is due to a quantum effect: sunlight is produced by fusion where particles fuse by a quantum tunneling process where a positron tunnels out of a proton to form a neutron.
All of chemistry is due to the Pauli exclusion principle: because electrons are fermions, they have to form distinct orbitals, giving all the richness of the periodic table.
Superconductivity is a purely quantum idea: in BCS superconductors, pairs of electrons combine to form Cooper pairs, which are bosons, and form a Bose-Einstein condensate. Flux pinning in superconductors allows levitation.
The nucleus of most helium atoms has two protons and two neutrons, making the nucleus a boson. Helium-4 forms a superfluid at about 3K.
Photons are bosons, and the population inversion in a laser is similar to a Bose-Einstein condensate.
Gold and cesium are yellow, copper is reddish, mercury is a liquid, and ten of the 12 volts in the lead-acid battery in your car happen because of relativistic quantum effects.
Footnote on QI from Wallace's book (p.372): "Before moving on, I feel obliged to note that we ought to be rather careful just how we discuss quantum suicide in /popular/ accounts of many-worlds quantum mechanics. Theoretical physicists and philosophers (unlike, say, biologists or medical ethicists) rarely need to worry about the harm that can come from likely misreadings of their work by the public, but this may be an exception: there are, unfortunately, plenty of people who are both scientifically credulous and sufficiently desperate to do stupid things."
Quantum immortality is a thought experiment that refers to the Many Worlds interpretation of quantum mechanics. The Many Worlds interpretation is just one of many interpretations. Quantum immortality is neither a property of collapse interpretations nor of superdeterministic interpretations.
The Many Worlds interpretation rejects the idea that there is only one of "you": because quantum particles are never in exactly one place, "you" are constantly diverging into a continuum of possible futures in which electrons in your body are in slightly different places, different photons get absorbed by your eyes, different neurons fire in your brain. In one universe, an old lady fails to notice a red light and t-bones a car, killing its driver, a young film student. In another, a neuron in the old lady's motor cortex fires differently: she pulls slightly harder on the steering wheel, takes a slightly different trajectory, and the student dies a tenth of a second later. In another, a neuron in the old lady's visual cortex fires differently; she becomes aware of the red light and slams on the brakes, injuring but not killing the student; the student spends the rest of their life in a coma. In another, the neuron fires earlier and she brakes earlier, merely giving the student whiplash. In another, the old lady notices early enough to stop normally at the light. There are infinitely many worlds and ways every future plays out. In most of the futures of the student in the car, the student dies. But in some of those futures, there is a film student who remembers getting in a car accident and barely surviving, and in others, there is a student who doesn't remember anything special about passing through the intersection.
Quantum immortality is the idea that there are always futures (however rare) where someone has barely survived (critically injured, perhaps, but alive for an instant longer) and futures (perhaps much rarer) in which they are completely fine. Any world with a nonzero probability amplitude exists.
https://en.wikipedia.org/wiki/Quantum_suicide_and_immortality
https://arxiv.org/pdf/quant-ph/9709032.pdf (Tegmark)
https://space.mit.edu/home/tegmark/crazy.html (Tegmark, SciAm article)
Past reddit threads:
https://www.reddit.com/r/QuantumPhysics/comments/n1w32e/i_have_a_question_about_quantum_immortality/
https://www.reddit.com/r/Physics/comments/5s5zoo/quantum_immortality_is_it_bullshit_as_a/
https://www.reddit.com/r/quantum/comments/p4r2g3/suggestion_to_the_mods_add_a_no_posts_about/
Please read and watch the following before asking about the DCQE:
https://www.preposterousuniverse.com/blog/2019/09/21/the-notorious-delayed-choice-quantum-eraser/
https://www.youtube.com/watch?v=RQv5CVELG3U
u/ShelZuuz breaks it down in a comment thread.
u/Educational_rule_956 [explains] (https://www.reddit.com/r/QuantumPhysics/comments/u1qifg/comment/i4jjobr/)
u/Muroid explains in a comment thread what went into the 2022 Nobel Prize in physics.
r/QuantumPhysics • u/ketarax • Oct 04 '24
Recently, there's been an increase of posts presenting a layman hypothesis. These do not belong in the sub. If you insist on being ridiculed for your grand illusions (where you're more professional than the history of professionals before you), r/HypotheticalPhysics welcomes you.
Infringements of rule 2 will result in a 1mo ban for some time to come, appeals will be ignored.
Read the rules.
r/QuantumPhysics • u/outofplace_2015 • 21h ago
Its quantum physics so the stranger the better.
r/QuantumPhysics • u/Dull-Drive5059 • 1d ago
I will start this with I am not a scientist but rather a philosopher. I follow science very closely.
In quantum theory, entanglement, wormhole theory there is a glaring issue in my eyes. My understanding is that it is believed that two quarks are connected by a wormhole. This doesn't make sense to me. In my head that would mean there would have to be a third force making this happen.
A simpler explanation in my opinion is that they aren't two separate pieces of subatomic matter but rather one that is existing in two or more locations at once. Am I wrong in my thinking? I've yet to hear anyone weigh in on this. I'm asking because I truly want to learn more.
I may be wrong and I fully accept that.
r/QuantumPhysics • u/TROSE9025 • 2d ago
Basic quantum mechanics utilizing the algebraic approach is recently being most closely applied to physical AI, quantum information, and quantum computing.
I hope this material provides assistance in learning operators through examples.
r/QuantumPhysics • u/Beautiful_Major3836 • 4d ago
me sinto isolado em meu quarto,descobri tantas coisas,mas não tem com quem compartilhar.
r/QuantumPhysics • u/catisadog1 • 4d ago
(I really don't know anything about quantum mechanics I only know what it is from some youtube videos so, I'm a nobody when it comes to quantum knowledge. But I had a question and I wanted to share it.)
I heard that quantum entanglement means two particles are completely in sync with each other so if we change one partical's one property it also change the second partical(I don't know if this is even true). So why are there no communication devices which use these. If we can adopt this technology communication would be instant, right?
I'm open to new knowledge.no hate please.
Thank you.
r/QuantumPhysics • u/Mynameis__--__ • 5d ago
r/QuantumPhysics • u/VARIENT__ • 7d ago
Why dismiss the question of where the particle was before the measurement like if we determine the pre measured state it could give us valuable insights into the particle fundamentals properties right I'm asking this question because this book doesn't revisit this topic in the later chapters i might sound like a stupid but I really want to know more about this
r/QuantumPhysics • u/kairo-misa • 7d ago
We literally learned that electrons have a de Broglie wavelength and can form an interference pattern in the double-slit experiment. Fine, cool.
But if you fire electrons one by one, what exactly is it interfering with? An interference pattern usually requires two waves to overlap. If there's only one electron in the apparatus at a time, does its wavefunction somehow go through both slits and interfere with itself? If so, what does that actually mean physically?
And the part that confuses me even more is that if you place a detector to determine which slit the electron went through, the interference pattern disappears and it behaves like a classical particle. I know the electron doesn't literally "know" it's being observed, but why does obtaining which-path information destroy the interference?
I'm trying to build an intuitive understanding of what's happening here. Is the "electron interfering with itself" just a mathematical description, or is there a physical picture that makes sense?
r/QuantumPhysics • u/TROSE9025 • 9d ago
This material focuses on quantum mechanics within the framework of operator-based linear algebra.
As of 2026, linear algebra-based quantum mechanics is rapidly becoming an essential requirement across both industry and academia—driven by its critical roles in quantum computing, quantum information science, Physical AI, and the development of 2-nanometer semiconductor processes.
I have made every effort to break down the complex concepts of functional analysis and explain them as simply as possible.
I hope this material proves highly useful to your studies.
r/QuantumPhysics • u/vedant_608 • 9d ago
I was reading my high school physics book, and it explained that if electrons and protons are the fundamental charges of the world, then the law of quantisation of charge means charges come in integral multiples of e=1.6×10^−19 C.
But then I learned about quarks, which don’t have integral multiples of e. For example, the up quark has +2/3e, and the down quark has −1/3e. Yet, they always combine in such a way that observable particles (like protons and neutrons) end up with integer multiples of e.
I also read that quarks can’t be isolated individually, because if you try to pull them apart, the force between them actually increases instead of decreasing.
So my question is: how is this possible? If quarks have fractional charges, why do we only ever see integral multiples in nature, and why can’t we isolate a single quark?
I think this is a question of quantum physics unless I'm mistaken.
r/QuantumPhysics • u/Remarkable_Piano_582 • 9d ago
Can you give me a practical example of a simple algorithm where a quantum computer is more efficient? I struggle to understand the usual ones, like the maze-solving example, which aren't very clear to me. They always seem too theoretical. Can someone provide a more concrete and intuitive example, please?
r/QuantumPhysics • u/Radiant_View_9959 • 8d ago
I bumped onto this paper purely out of curiosity and admitting I never felt "comfortable" with the measurement problem.
https://arxiv.org/pdf/2509.11609
The paper and experiment seems to prove the Bohmian mechanics is actually true and real. Yet, and this is the question, I see thus far little to no momentum on the subject. Seen a couple of interviews on the matter (namely https://youtu.be/VbXEc9vpeIM?si=-_cfxGHG_VD_Z8dN ) but no actual "breaking news" on the matter.
Why is that? Is it normal for these kinds of experiments somewhat pulling the curtain on existing beliefs, to be left as background noice in the community?
Again, I am no-where near a scientist or a student on the matter.
Purely a spectator ... 😇
r/QuantumPhysics • u/Alon_F • 9d ago
I heard that if two atoms fuse together the new atom's mass would be less than the combined mass of the two parent atoms, because during fusion energy escapes as a photon. Is that true? Does energy really make objects heavier? If so how can a photon be massless?
r/QuantumPhysics • u/RiskOperator • 10d ago
I am someone who just started studying statistics, whilst studying the sampling distribution and the standard error, I feel like the concepts are someway connected to oscillation/harmonic motion and maybe deep down quantum mechanics.
Could someone please link me to a video lecture series on this specific topic?
r/QuantumPhysics • u/cantcreatenordestroy • 11d ago
I just learned that light is an electromagnetic wave and that it is a disturbance caused to the electromagnetic field or rather the yank alright and, i also learned that electron is neither a wave or a particle like if light is a disturbance in the electromagnetic field that electromagnetic field is caused by an electron and that electron is basically unknown then what actually is waving? what is an electron? all these years spent learning abt borhs models etc and drew so many electronic configurations considering electrons as subatomic particles represented with dots imagined that particles and tried to understand current like nothing makes sense rn can someone explainnn.😞
r/QuantumPhysics • u/vedant_608 • 12d ago
Hi, I’m new to quantum mechanics. I was trying to model what the orbitals for oganesson might look like, and I keep seeing that we need to treat it as a “hydrogen‑like” atom. I don’t fully understand why we can’t just solve the Schrödinger equation for the actual atom itself without using such approximations. Is this a fundamental mathematical limitation, or is it just that the computation becomes impossible in practice?
r/QuantumPhysics • u/you_should_study677 • 12d ago
Reddit doesnt just solves doubts of a peer but actually increases it, i am saying this bcz i in previous post asked a question about heisenberg uncertanity and photon relation with it. I get lot of comments on it but my doubts doesnt seem to vet low it increased. The doubt is as:
Δx of photon, V → ΔP↑ ⇒ Δν↑ ⇒ Δλ↑. Conclusion: the speed of light doesn't change at all for a photon — it's constant, forever. Δν of a photon can change indefinitely, but the speed of light stays as it is.
What happens when a fast-travelling entity emits light in the direction of its motion? The speed of light never changes, but in relative motion, shouldn't the speed add up to the speed of the entity? Isn't this a contradiction?
Analogy: relative speed = c. If we consider that an entity emits waves while it's travelling — the wave has some (λ, ν), the entity has its own speed, and the wave itself travels at c. If we want the relative speed to stay constant, then I think the string (wave) compresses. That's the only way the relative speed of the thing stays c — the string compresses.
Imagine it like the wave of the photon compressing — meaning frequency increases. And the wavelength — maybe it doesn't change, or maybe it does. But according to Einstein, when an entity moves at c, time dilation happens. So what happens exactly — does the travelling frequency of the photon remain the same and just time slows down? Or does the frequency of the photon decrease, while the relative speed still stays "c"?
This is my opinion and my own understanding only
So what happens exactly? Tell me your opinion on it.
r/QuantumPhysics • u/No-Relation-5069 • 13d ago
I have been mesmerized by the world of quantum physics, but haven't been able to grasp the concepts from the very few lectures I can find for free. Do y'all have any suggestions? I am open to book PDFs, but please make sure that they are free of cost, as my parents are not going to buy more study stuff,f as I am already in class 11th
r/QuantumPhysics • u/Stairwayunicorn • 15d ago
Is the direction of travel of a newly created photon parallel or perpendicular to the direction of the parent electron losing its stored energy?
The orbital cloud absorbing a photon I can understand. But then what? the electron can't sustain it's heightened level and collapses back to its rest level and squirts out a photon, but how is it oriented? does the collapse occur in a straight line or a spiral?
r/QuantumPhysics • u/TROSE9025 • 16d ago
The quantization rule of de Broglie in the 1920s is not an arbitrary guess, and demonstrates the direct mathematical consequence of treating the electron as a standing matter wave. It is hoped that this posting provides minor assistance to those who are initiating modern physics and quantum mechanics for the first time.
r/QuantumPhysics • u/Far-Professional-786 • 17d ago
Hello! I'm currently Studying the Math behind Cooper pairs to understand Superconductivity, but I'm a little bit stuck on how the approximation of "Vkk' = -V" was made by Leon Cooper. I'm currently following along Michael Tinkerham's "Introduction to superconductivity."
(Link to Book: https://archive.org/details/introductiontosu0000mich/page/44/mode/2up)
These are the rough notes I have on the topic so far, and I wanted to ask if anyone can explain the logic Leon Cooper used to approximate Vkk' as -V?
(Also if anyone finds major errors within my notes/understanding, constructive feedback on that would be appreciated.)
r/QuantumPhysics • u/Vivid-Height9891 • 18d ago
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created this short educational video to explain the fundamentals of quantum computing in simple Hindi using visual illustrations. I'd love feedback on the clarity, accuracy, and presentation.
r/QuantumPhysics • u/Random_dude64836483 • 19d ago
Is it just reading papers, or do y'all have any other resources instead of just straight up reading papers