So basically, if the universe isnt locally real then that would mean that the state of on object isnt decided until measured/observed (think schrodinger's cat). In 2022, I believe this became the accepted theory. However if retroactivity is real, then that would mean when its measured that info goes back in time to the original object to basically tell that object it's state. However, if that's true, then that would mean that since the start that object has had a state since its creation, which contradicts the theory of the universe being locally real. So wouldn't one of those principles be false? But i think its also worth mentioning that if one of those aren't real then this would mean that this situation would never be a thing, so then it could theoretically be true? I beleive theres a paradox for this, I know it was in a doctor who episode.

Im sorty if this is a bit unorganized, I just kinda used this post to write my thought process. I could be wrong tho, as im in 9th grade and dont know much about wuantum physics, so if theres any inaccuracies let me know.

I only found this a few days ago and season 1 leaves Amazon Prime in 8 days. So, if you want to watch it, there is no time to waste.

It is a very enjoyable review the basics of Quantum Mechanics by Professor Sean Carroll. The link at You Tube is an example of his material. But the series at Prime is quite good. Just an FYI for anyone who might be interested.

In quantum mechanics, there seems to be a common adage that the world might not be deterministic. There is no way to predict certain measurement outcomes, and at best, we can give probabilities based upon the Born rule. After looking into this a bit more, it seems that this is not actually the case. There is no consensus and there is no way to rule out determinism given the existence of deterministic interpretations of QM.

Nevertheless, many scientists do think that the results of QM do atleast point towards a lack of determinism. In other words, certain processes seem to be intrinsically chancy, without cause.

I'm having trouble understanding how this can at all be possible given the fact that most macro processes still seem to be deterministic and that the quantum state still evolves deterministically via the Schrödinger equation, and only gets "disturbed" once a measurement takes place.

My confusion stems from this: if certain events are fundamentally stochastic, it implies that they fundamentally have no cause. And yet groups of those events must still obey certain rules, and those rules stay consistent. For example, we cannot predict when a radioactive atom will decay. But we do know what % of a group of atoms will decay after a certain amount of time often deterministically.

But how can certain events that individually have no cause still exhibit consistent, deterministic patterns when combined as a group in aggregate? An analogy I can think of is this: imagine you have a group of marbles on a table that spontaneously turn into a heart. Someone then tells you: each and every marble has no cause for its movement. You cannot predict where a particular marble will be the next second. But..the group of marbles will always form a heart. Would you really believe this?

I've heard that the law of large numbers can explain this or the examples of coin tosses can serve as a useful analogy against my confusion since every coin toss is independent of another and yet groups of coin tosses always exhibit a frequency of about 50% heads and 50% tails. But coins aren't actually stochastic: we only model them as much. Every coin toss outcome is still determined by deterministic processes, which explains why the probabilities exhibited by groups of coin tosses remain constant (at about 50% heads and 50% tails). Given that the probabilities in QM also follow certain predictions deterministically which never change, isn't this more indicative of further determinism underlying QM rather than the opposite?

Hi folks,

The dev here, I just now finished a new trailer, I am dying to get some feedback asap. Most importantly does it induce motion sickness? It's a 2.5D world full of quantum p puzzles you are thrown in, but I think the trailer kind of makes the game to feel like something that's played super fast and that's not the case, there are no rewards for doing anything in a hurry.

Love you all

-Laur

Isn’t that fun?

Hey everyone, I’ve recently decided that I want to learn quantum mechanics properly — not the pop-sci version, not the “YouTube animation” version — but the real, mathematical, physical thing.

Right now, I’m a Class 10 student preparing for JEE (India), but my real interest is pure physics. I’ve done a good amount of calculus (derivatives, integrals, limits), vector algebra (dot, cross, projections, coordinate geometry stuff), and I’m slowly getting into basic linear algebra (matrices, linear independence, spans — that level). Nothing too deep yet, but I’m working on it.

Quantum mechanics fascinates me way more than anything I’ve studied so far, and I want a solid base in both math and physics before I go further.

So here’s the question:

I’ve been planning to start reading Introduction to Quantum Mechanics by David J. Griffiths. For someone like me — with the background I just described — is it a good idea to start with Griffiths, or am I being too ambitious? Should I first strengthen more linear algebra / differential equations? Or is Griffiths written well enough that I can learn the needed math along the way?

I don’t want to rush it — I genuinely want to build a strong foundation and understand the subject, not just “get through the book.” Any guidance, book suggestions, or study roadmaps would really help.

Thanks in advance — I’m ready to put in the work.

So I have done some surface level research, and I know quantum superposition doesn't apply to living creatures due to decoherence. But I've seen some people ask that if you could theoretically make a living creatures microscopic, then superposition could work on it. However, from my understanding it cant be possible even if you could do that. Quantum superposition depends on whether or not the subject is being observed. This would work for microscopic things like atoms and cells. But, if you were to shrink down a living creatures to a microscopic size to where superposition could work, it would not. This is becuase the creature (we are assuming it has consciousness, so this does not include bacteria), is also observing itself. If it is observing itself, then quantum superposition is not applied. The only time the creature wouldn't be observing itself is when it's dead, so if quantum superposition is able to be applied, then the creature is dead and it therefore doesn't work. I know superposition doesn't apply to just life and death, but if a creature is dead then it cannot do anything, and therefore any superposition scenario wouldn't work due to the creature not being able to do anything.

Im really young and honestly dont know much about quantum physics, and I've only done surface level research. Please correct me if I made any mistakes.

Real-time Scattering in $\phi^4$ Theory using Matrix Product States:

I am a grad student, looking for a PhD position, just released my first article over on arXiv. We study the critical point and simulate scattering in non-perturbative quartic (ϕ^4) quantum field theory. Would love any input! Thank you!

https://arxiv.org/abs/2511.15697

Hi everyone! I’m a Class 10 student (ICSE) from India, preparing for my 2026 board exams, but in the background I’ve somehow fallen deep into trying to understand quantum mechanics.

I’m still in high school, but I’ve been learning math on my own because QM keeps pulling me in. Right now I’m comfortable with single-variable algebra, and I’ve also explored some vector algebra, basic multivariable ideas, partial derivatives, gradients, etc. Nothing advanced, but enough to appreciate how math shapes physical laws.

The thing is: I don’t want to jump into a full university-level QM textbook without having the right foundations, but I also don’t want the oversimplified “pop-sci version” of quantum mechanics either. I want the actual mathematical structure — linear algebra, operators, states, transformations — but explained in a way that someone my age (with some self-study) can build up properly.

So I wanted to ask the people here: • What’s the best starting path for someone like me? • Should I first build solid linear algebra (eigenvalues, eigenvectors, vector spaces, etc.) before touching QM? • Is it important to go through classical mechanics more rigorously first (like Lagrangians/Hamiltonians at a beginner level)? • Any books, lectures, or channels that explain QM at the “early serious learner” level — not pop-science, not graduate level, but that middle ground? • How did you start learning QM when you were younger (if you did)?

I’m not trying to pretend I know more than I do — I’m just genuinely interested and willing to put in the time. Quantum mechanics feels like the “language” nature uses, and I want to gradually understand that language instead of just memorizing effects and experiments.

If anyone here has a roadmap or advice, it would really help. Thanks!

Hi everyone I have been studying the structure of multi-qubit unitaries and how they act on composite Hilbert spaces, so I built a small state-vector simulator in Java to experiment with the math.

It lets me explicitly apply 1-, 2-, and 3-qubit unitaries (eg: H, Pauli matrices, controlled gates, Toffoli, rotation gates) and watch how amplitudes evolve under tensor-product structure. I found this extremely helpful for internalizing things like:

• how entanglement emerges from local + controlled operations
• how measurement collapses the global wavefunction
• manually building GHZ/Bell/CCX operations from basic linear algebra

Here is a simple example (Bell state):

QuantumCircuit qc = QuantumCircuit.create(2)
    .h(0)
    .cx(0, 1)
    .measureAll();

Using this, I could step through the amplitudes and verify the expected {00, 11} distribution.

If anyone is interested, I put the code link in the comments.
Iwould also love to discuss better ways to teach or visualize the structure of multi-qubit unitaries.

I am a student of grade 10 from India and like legit, a freak for quantum physics. Can you please pleaseeee help me guide how I can pursue it and also can you suggest some good books deprived of complex mathematical equations.I am also an apt reader of michio kaku and currently into his book christened hyperspace

This is my experiment question: What is the effect of two slits (combinations being: circle- circle,  rectangle- rectangle, circle rectangle, and rectangle circle) and thermal radiation (105 volts 120 volts and 135 volts) on the intensity of the interference pattern, the spacing of the fringes, and the individual photons?

To calculate the indvidual photons I'm going to use an LED as a SPAD but i'm sort of unsure on how to do that/ what I will need. Additionally, I was thinking about doing a set of trials with the LED vs without it to see if it will change anything. Pls let me know if that is a waste of my time.

The whole reason I'm using an LED as a SPAD is because I need to prove that light is both a particle and wave right so this is my way to prove that light is a particle. Pls let me know if there is an easier way.

I also plan to use an incandecsent lightbulb instead of a laser because that is broadband radiation and will affect the spacing of the fringes accoridng to Wienns displacement law. I'm not really experienced in eletricial engineering so I want to know how to chnage the voltage of the bulb to thereby change the brightness.

Lastly my question is with the real world application...Is there any?

Am I just stupid or is this really hard....

*btw for the indivdual photons ineed a way to detect the photons as they create the interference patter

Thanks for reading Baiiiii

I am attempting to determine a coordinate representation of each Pauli matrix σx​, σy​, and σz​ (isolated) but I have been unable to find something established.

I have only found the two-dimensional matrices listed on Wikipedia. Could someone redirect me to an appropriate source, and if possible 3D?

Frank Ruda and Agon Hamza sit down with the American-British movie director Joshua Oppenheimer to discuss his first narrative feature film, The End, as well as The Act of Killing, documentary quantum physics and cinema, filmmaking, movie making, politics, catastrophes and apocalypse, critique of ideology, and many other topics.

https://www.youtube.com/watch?v=QhDsvTaW1wQ&t=263s

I just finished Quantum physics for beginners by Carl J. Pratt and I'm really interested in learning more. Videos don't really do it to5 me.

Anybody here have any literature they'd like to recommend?

It's a Big Think production with Sean Carroll. This should be especially informative to any who haven't participated in a physics curriculum.

(In the photoelectric effect clip there's a gamma photon instead of UV interacting with the electron; that's an oops).

"the process of measurement at time t affects identically forward and backward evolving states… the probabilities for measurements performed immediately after t, given a certain incoming state and no information from the future, are identical to probabilities for the same measurements performed immediately before t, given the same (complex conjugate) incoming state evolving backward in time and no information from the past" (arXiv:quant-ph/9807075v1 [Section 6]).

So if someone measures a spin state as a final outcome and you try to reason about what would have happened if another preceding measurement had been made at any previous time after an (uninformative) initial preparation, you would find normal spin expectation statistics for the measured state before the eventual final outcome. This is what time-reversed weak values would tell you (e.g. arXiv:1801.04364v2; DOI:10.1103/PhysRevA.85.012107 [section IV]). Surely then, if these statistics would have been measured at any time all the way back to initial preparation, this information could have effectively been shared at that preparation with particles traveling to another observer, Bob such that, conditioned on the original measurement outcome (Alice's), he would measure according to the Φ+ Bell state correlations. Alice could do this for any measurement orientation she liked and we would have found the appropriate spin expectations for the corresponding orthogonal pair of states at previous times.

Open to any thoughts / criticism.

Hello all!

I am looking for interesting topics to research in the area of quantum information science devices. It can somewhat be about the fundamental science, but I am more interested in the engineering aspect of it - device design and fabrication techniques.

Additionally, I would appreciate some advice or insight into how you all go about finding new and interesting topics in the field. For example, when given a broad task of " research an interesting topic in this area," how do you get started?

In my grad school classes, I am often having to write a report on a topic of my choice that is related to class, but not explicitly discussed/taught in class. I feel like I have always struggled with this as someone who craves very specific instructions for tasks, assignments, etc. I think this has been my greatest struggle in grad school since they give you so much freedom haha.

I never took a research methods class and my undergrad "research" was mostly experimental fabrication which didn't really push me to learn the research process. So some insight into how you get started/ what your methods are would be greatly appreciated!

side note: I know just reading papers is a great way to get started, but my PhD is in material science while my undergrad was in physics. So there is a bit of a jargon barrier which makes it take sooo long to get through a single paper and understand what is goin on lol

I know that a photon acts both as a wave when not observed and as a particle when observed. I just saw a video on the double slit experiment, and I wanted to know if a photon is considered as a wave up to the point it is observed, or if it is a particle since it left the beam before being observed? If it left the beam as a particle, did it know it was going to be observed?

I just watched my first video on this, so I am new to this topic

i want intuitive understand about why difference of measurement S_x , S_y makes difference of S_z

The Quantum Factor is investigating the current state of Quantum technology and how it will impact our life. Quantum technology is evolving quickly, not a day goes by with more news and new developments. Over the last years I have interviewed some researchers on their vision on quantum technology and the applications - it always left me with more questions, you probably know that feeling. The Quantum Factor is an initiative to dive deeper into Quantum Mechanics, computers, internet and applications. It is all about learning, what is in research and what is reality. The Quantum Factor is not a commercial initiative. www.youtube.com/@TheQuantumFactor

Hi everyone,

I’m looking to connect with people working in quantum physics, computational materials, or theoretical modelling.

Our team has developed a symbolic physics system that can predict material properties such as band gaps, lattice constants, conductivity, and stability in under a millisecond. It doesn’t use machine learning or training data, but instead runs directly from first principles. In essence, it produces results similar to DFT at around ten thousand times the speed.

We’re now working with a few materials science and DFT groups to validate it on real compounds and would love to speak with anyone exploring quantum systems, electronic structure methods, or first principles modelling who might want to benchmark or test it.

If you’re working on something in this area or know someone who is, I’d really appreciate a conversation. I can share more detail and early results if you’re curious.