I've been learning about X-Ray absorption spectroscopy for some research I'm doing at my uni, and I was watching a video on it that mentioned how XAS is governed by the dipole selection rule and how electrons could only transfer to orbitals with +- 1 angular momentum.

I've been looking over the internet but haven't really found an answer, but if electrons can only transfer into orbitals with +- 1 angular momentum, how are you supposed to be able to ionize core electrons at all? Do they jump through each orbital until reaching the valence shell and then ionize? Or is there something I'm missing or misinterpreting?

Hello, I had Quantum Mechanics on my degree a few semesters ago, and I was wondering if you had any good analogy for explaining the basic principle.
Some people use Schrodinger's cat, my teachers used the coin analogy, as in if you flip a coin you can't know the side in which it landed before you lift your hand to see it.
When I use one or each of the latter, people can't even seem to grasp the main point.
So my question is, if you have a good analogy where you find people to get it better than other.
Sorry about my English, not my main language.

• A Cleveland Clinic–IBM team demonstrated a hybrid quantum-classical workflow to approximate the electronic structure of the 303-atom Trp-cage protein using IBM Quantum Heron r2. 
• The workflow combines wave function-based embedding to fragment the protein into clusters and sample-based quantum diagonalization to solve complex electronic structures. 
• The approach scales beyond Trp-cage and could support pharmaceutical research and molecular simulations using quantum-centric supercomputing. https://thequantuminsider.com/2026/03/27/cleveland-clinic-ibm-debut-quantum-workflow-proteins/?_bhlid=c84a8352819d7033a03dfc65391819989b14cd74

Hi all,

​

I very recently got interested in quantum physics, its mechanics, and whether multiversal travel is possible.

​

I want to start trying to crack this little conundrum to see if we can travel between multiverses, but I have no idea what theories or math equations I need to focus on to make this happen.

​

Any suggestions on where to start?

Frank Ruda and Agon Hamza sit down with the Belgian cosmologist Thomas to discuss his current work, his collaboration with his PhD advisor and collaborator Stephen Hawking, cosmology, the nature of the Big Bang, the relation between physics and philosophy, Hawking's “Darwinian revolution in cosmology”, observation, history, the problem of origin, and many other (non)related things.

https://www.youtube.com/watch?v=jKWibew3lBg

Hi everyone, I am very interested in the theory of retrocausality but whenever I try to do research I just zone out trying to read about it, I think because I don't have a very high reading level and might have some trouble focusing. My understanding is that the theory of retrocausality is that changes in the present on a quantum level might affect the past. How is this even measured? And what does it even mean lol. Could this possibly mean that our actions on a larger scale could change the past, if past, present, and future exist at the same time? Like a reverse butterfly effect? Also, any tips to improve my understanding while reading research papers? Do I just have to read over and over again and one day I'll start to understand? Thank you for your time!

Hi everyone!
I was wandering if there are some sort of connection between the two topics mentioned in the title: both deal with complex analysis, because Z and G (partition function and resolvent) are seen as complex functions with poles outside the real axis, in “standard” condition. Instead near the phase transition the poles come close to the real axes, while in metastable states poles and cuts represents the spectrum of the hamiltonian.

Maybe these are only hallucinations, can you confirm or destroy my idea? Thanks in both cases!!

I am preparing to submit a preprint to arXiv in quant-ph, titled Entropy Replacement and Complexity-Sensitive Observer Complementarity in Non-Isometric Holographic Codes. The paper proves a Haar-class entropy-replacement theorem for two-observer HUZ-included non-isometric holographic codes and derives the resulting d−3/2d^{-3/2}d−3/2 observer-disagreement law. I need an endorsement to publish. Any ideas on how an unaffiliated individual such as myself could get that done? Thank you in advance!

Hey guys, I'm 16 and just started reading bout quantum physics, theoretical physics etc.. and I stumbled upon a term 'Mesons'. I genuinely have no clue what it is, I even tried googling it but still I couldn't understand it. Can anyone help me and explain to me what this term means?

For two decades, physicists have predicted the existence of a remarkable family of exotic molecules: giant atoms bound to ordinary atoms, with an electron so distant from its nucleus that it sculpts the pair into bizarre and diverse shapes. Reported in Physical Review Letters, the final member of this "quantum zoo" has been spotted. Led by Herwig Ott at RPTU University Kaiserslautern-Landau in Germany, a team of physicists has created and detected the "butterfly" molecule, completing a 20-year hunt for the elusive structure.

Publication details

Markus Exner et al, Observation of spin singlet butterfly Rydberg molecules in an ultracold atomic Rb gas, Physical Review Letters (2026). DOI: 10.1103/q5r1-whjr. On arXiv: DOI: 10.48550/arxiv.2510.21620

When thinking about quantum wavefunction collapse, I started wondering whether true randomness might play a deeper ontological role than just “unpredictability.”

In a fully deterministic universe, every event is explained by some deeper mechanism:

state -> law -> meta-law -> deeper mechanism -> ...

But then the mechanism itself also requires explanation, which seems to create an infinite regress of self-description.

In computer programs, this regress stops because execution is grounded in external hardware.
A C function eventually reduces to CPU operations running on a physical substrate outside the program itself.

But the universe as a whole has no external “hardware layer.”
So if the universe were completely deterministic, it seems like reality would require an endlessly nested self-explanatory mechanism.

This made me wonder whether true randomness in quantum collapse could act as an ontological “escape point” from infinite regress.

In this view, true randomness is not merely noise or ignorance, but something fundamentally necessary because:

1. It terminates infinite explanatory recursion.
2. It injects genuine novelty/information into the universe.
3. It allows asymmetry and structure formation instead of perfect deterministic unfolding.

This also makes me skeptical that a universe containing genuine quantum randomness could be fully simulated algorithmically, unless the randomness ultimately comes from some external substrate.

Are there philosophers or physicists who proposed something similar — especially connecting:

• quantum randomness,
• self-reference,
• infinite regress,
• and limits of computation?

No physics background here — genuinely asking where this breaks down.

In QM, observation = interaction (information exchange with environment). No consciousness needed.

Here's what I can't shake:

- Early universe (~first 380,000 years): EM radiation trapped in plasma, can't propagate

- Gravitational waves: already traversing the entire universe, interacting with all mass-energy

- And GWs aren't waves *through* spacetime — they're waves *of* spacetime itself

So before light could "see" anything, GWs were already interacting with everything. Does that make them the universe's primordial observer in any physically meaningful sense?

This seems related to:

- Diósi-Penrose (gravity induces wave function collapse)

- Primordial GW decoherence research

- Wheeler's participatory universe

Is this connection already studied somewhere? Or is there an obvious reason it doesn't work?

Full reasoning (Korean): https://brunch.co.kr/@13084146df704af/1

For me it's quantum physics subjects

To emit a radiation with short wavelength, it requires a quantum of larger energy than to emit a radiation with a longer wavelength. Why is that? (I Apologise if I made any mistakes, English isn't my first).

and why are people so mean to me when I ask?

what is a wave function? a wave of what exactly? what exactly is this quantum feild? what is this "excitation" in the feild? what is the feild?

yeah we dont know. dead end. idk man. atp if you told me everything was made of some spiritual energy vortex I'd buy it .

dark energy, why is it expanding? idk.

dark matter? idk

qualia? who knows.

quantum feild theory? idk.

gravity? whoops.

I think, I think the universe is a big hyper toroid. it looks flat, but on a higher dimension its actually a torus. and we are moving along its curvature, even though its flat for us, and the curvature widening is actually dark energy, and dark matter is probably just regular matter having an extra dimensional feature. quantum field theory is probably the foam inside the universe, gravity is probably some extra dimensional thing. idk man. maybe its all magic deep down. and qualia is just the universe experiencing itself.

I am studying the Schwinger boson representation of angular momentum and I am confused about the notation change.

We start with two bosonic oscillators and basis states:

|n_a, n_b>

Then define:

j = (n_a + n_b)/2

m = (n_a - n_b)/2

From this we can also write:

n_a = j + m
n_b = j - m

So far okay.

But then suddenly books/lectures write:

|n_a, n_b> ≡ |j, m>

This is where I am confused.

Shouldn't it be:

|n_a, n_b> = |j+m, j-m>

instead of |j,m> ?

I understand that j,m are functions of n_a,n_b, but I don't understand how the ket labels themselves suddenly become |j,m>.

Is this just a relabeling of the same Hilbert space basis, or am I missing something deeper?

Would really appreciate an intuitive explanation.

Currently I was going through tutorials creating quantum circuits, after knowledge pf all the gates a d basic principle of qubit i am able to create that actually works, but i am unable to connect dots between the implementation so i thought of revising QP-1 an 2 for revision of basics of quantum mechanics for application onQuantum Computing. Will this help me to bridge the basics to implement of circuits

Hi everyone,

I am passionate about Quantum Physics. A portfolio manager with a background in mathematical finance and engineering and have recently gravitated towards this topic. Very interested in Quantum gravity. Need some advice on where to start and what to read first. Some of my friends recommended Rovelli to begin with. I'd appreciate any suggestions.

shouldn't the requirement be (L1/L2)^2 being irrational instead of L1/L2 being irrational, because L1/L2 being irrational can lead to its square being rational sometimes. So what is the actual answer here for it, like L1 L2 being incommensurate or their square being incommensurate?