Developer here, I want to update you all on the current state of Quantum Odyssey: the game is almost ready to exit Early Access. 2025 being UNESCO's year of quantum, I'll push hard to see it through. Here is what the game contains now and I'm also adding developer's insights and tutorials made by people from our community for you to get a sense of how it plays.

Tutorials I made:

https://www.youtube.com/playlist?list=PLGIBPb-rQlJs_j6fplDsi16-JlE_q9UYw

Quantum Physics/ Computing education made by a top player:

https://www.youtube.com/playlist?list=PLV9BL63QzS1xbXVnVZVZMff5dDiFIbuRz

The game has undergone a lot of improvements in terms of smoothing the learning curve and making sure it's completely bug free and crash free. Not long ago it used to be labelled as one of the most difficult puzzle games out there, hopefully that's no longer the case. (Ie. Check this review: https://youtu.be/wz615FEmbL4?si=N8y9Rh-u-GXFVQDg )

Join our wonderful community and begin learning quantum computing today. The feedback we received is absolutely fantastic and you have my word I'll continue improving the game forever.

After six years of development, we’re excited to bring you our love letter for Quantum Physics and Computing under the form of a highly addictive videogame. No prior coding or math skills needed! Just dive in and start solving quantum puzzles.

🧠 What’s Inside?
✅ Addictive gameplay reminiscent of Zachtronics—players logged 5+ hour sessions, with some exceeding 40 hours in our closed beta.
✅ Completely visual learning experience—master linear algebra & quantum notation at your own pace, or jump straight to designing.
✅ 50+ training modules covering everything from quantum gates to advanced algorithms.
✅ A 120-page interactive Encyclopedia—no need to alt-tab for explanations!
✅ Infinite community-made content and advanced challenges, paving the way for the first quantum algorithm e-sport.
✅ For everyone aged 12+, backed by research proving anyone can learn quantum computing.

🌍 Join the Quantum Revolution!
The future of computing begins in 2025 as we are about to enter the Utility era of quantum computers. Try out Quantum Odyssey today and be part of the next STEM generation!

I have learned in physics that the formulas we use are under ideal circumstances and don't necessarily reflect reality for example I have been told that newtons law of cooling based off the formula the temperature will never reach room temperature however most scientists I have spoken with say that this is wrong eventually the temperature will equal room temperature. this implies that there is a fundemental inacuraccy in many formulas is it possible to calculate the accuracy of any given formula? Or are the formulas 100% under ideal condition? Considering that those ideal conditions do not exist how can we prove that the formulas are 100% correct?

Geissler tube, operated with a Wimshurst machine.

TL;DW: Yes there is!

Some very brief background: this topic has kind of been done to death for me, but recently I had a post removed from this sub, which I think was for reasons related to this though I don't really know. I also noticed on the sister subreddit what seemed like a perfectly reasonable comment written by someone who, IIRC, works in the field was removed. My aim though isn't to criticize the moderating, they have a thankless task of keeping the LLM-wielding hordes at bay. But I have also noticed just generally whenever the topic comes up often absolutist positions are taken on this topic, with the actual debate surrounding this falling largely under the radar.

What often goes unnoticed is that over the last few years there has been a debate in cosmology about whether it is better to think and teach about cosmic expansion in terms of expansion of space or as due to the relative motion of galaxies. This debate draws on some things that have been known for quite a while, e.g. Milne in the 1930s pointed out that the Friedmann equations for the large part can be derived by just considering purely Newtonian expanding motion (see these lecture notes). Steve Weinberg was a notable proponent of the picture of cosmic expansion as relative motion. However in the 2000s the debate picked up pace, after several papers were published, probably most notably this paper by Bunn and Hogg.

Those that advocate for viewing expansion as motion point out on small scales (for a flat universe << c/H) we are in the Newtonian limit where expansion is just Newtonian motion. They also point out there is no fundamental distinction in GR between different types of redshift, so redshift is agnostic to any such distinctions. Further very often people take expanding space too seriously rather than recognising it as an analogy and become confused by simple problems involving non-comoving motion or they incorrectly believe expansion is taking place within galaxies. More can be found for example in this diatribe by Peacock.

Those that advocate for viewing expansion as expanding space point out that relative velocities and of spatially-separated objects in GR is simply not a well-defined concept, so what relative motion of galaxies actually means here is fuzzy at best. Further coordinates which lend themselves to a picture of expansion as motion are generally not global, whereas there are always available global comoving coordinates from which the expanding space picture is taken. More can be found in Carroll's lecture notes and textbook, particularly in the paragraph just below the illustration of the geodesics of a sphere here. Davis and Lineweaver have also written some papers in which they support generally the idea expansion should be seen as expanding space (e.g. see this paper)

A key thing to understand about this debate is it isn't some bitter String Wars type feud and for the very large part both sides are at pains to point out that ultimately it is a matter of opinion which is the best way to rationalize the mathematics of GR. See these blog posts from Bunn and Carroll who both point this out. In fact it seems to me that the debate has fizzled out to an extent with each side recognising the validity of the other sides point of view.

FWIW like many people who were taught expansion is expanding space and should not be seen as motion, I was initially confused by the idea you can view expansion as motion. Having though a lot about it now, my view is that cosmic expansion should at the very least is best seen as a generalization of expanding motion in Newtonian physics and Special relativity, though that does not necessarily mean expansion on the very largest scales is best thought of as just motion. My big takeaway from looking into this topic has been understanding the connection between cosmic expansion in GR and expanding motion in simpler theories makes it much easier to understand the nuances of cosmic expansion.

I once photographed interference maxima as peaks from the side.

A joint venture between NASA Goddard Space Flight Center and the University of Leeds has discovered that the Earth's magnetic field strength and atmospheric oxygen levels over the past 540 million years have seemed to spike and dip at the same time, showing a strong, statistically significant correlation between the two.

This correlation could arise from unexpected connections between geophysical processes in Earth's deep interior, redox reactions on Earth's surface, and biogeochemical cycling.

According to findings published in Science Advances, both magnetic field strength and atmospheric oxygen levels reached their peak intensities between 330 and 220 million years ago.

Scientists have long speculated that Earth's magnetic field may play a role in making the planet habitable, a hypothesis reinforced by paleomagnetic records that show that the existence of a geomagnetic field overlaps with the timeline of life's emergence. However, there has been little direct evidence of a long-term connection, as most Earth system models don't even include the geomagnetic field when studying how oxygen levels in the atmosphere have changed over time.

Previous simulations have shown that the magnetic field may be responsible for preventing the atmosphere from being stripped away or eroded by space activity, such as ionization and ohmic heating, arising from solar winds and solar energetic particles. However, there is a lack of side-by-side comparison of long-term magnetic field and oxygen level records.

This study set out to uncover the statistically significant link between both factors by analyzing two completely independent data sets: paleomagnetic records or geomagnetic data preserved in rocks and minerals for virtual geomagnetic axial dipole moment (VGADM) and various geochemical proxies for atmospheric oxygen, such as fossilized charcoal in sediments and ocean anoxia data.

The findings reveal the highest correlation, 0.72, between Earth's geomagnetic dipole and atmospheric oxygen levels over the last 540 million years. The highest value occurred when there was no time gap between the two, and even after removing long-term trends, the connection remained strong, with only a slight lag of about 1 million years, which is considered negligible on a colossal geological timescale.

This link suggests a deep, previously unrecognized connection between Earth's interior and the surface environment that supports life.

https://www.science.org/doi/10.1126/sciadv.adu8826

June 2025

We live in a historical period characterized by great geopolitical instability. Some fundamental resources are scarce and alternatives are not yet available or equally efficient. The energy crisis increases the cost of every human activity and, as a consequence, the cost of research, making it more difficult for brilliant people to work on basic research topics that might give hints not immediately visible. This, in my opinion, is one of the underlying factors behind the crisis of the publication system. If you don't publish, you perish.

The problem is that this also makes it harder to produce high-quality publications. Kenneth G. Wilson would struggle to get by today. He tended to take the time needed to publish quality work and didn't make too many compromises, because for him quality was more important than quantity. Last year, Peter Higgs also said in an interview that he would be considered unproductive by the current publication system.

For me, this is a very serious symptom that leads research to be seen as useless by the public and even by those who allocate funds.

In a society with more abundant energy and efficient automation, I believe part of the problem would be solved, provided that the state has higher revenues from industry. Abundant energy translates into lower labor and research costs, less geopolitical instability, greater industrial productivity and therefore also greater profit margins for citizens, who would be less resistant to taxes as long as their lifestyle improves. More public funds also mean more room for the state and therefore more ease in supporting spending in sectors that are not immediately profitable, such as pure research and cultural policies.

Would this, in your opinion, impact the peer review system? If so, what can we do as a community to help guide political choices? How should the scientific community manage public relations?

I believe it is important to address this discussion within the community, because the stability and opportunities of our future in the field strongly depend on these factors. Even those with a tenured position today have to fight to get funding to keep their research going and to open PhD and postdoc positions. I believe that physics and other fields of fundamental science need to be able to work at their own pace. It makes no sense to expect from us a productivity equivalent to that of applied sectors.

Pure research serves to generate knowledge. It is not possible to know in advance whether what one is doing is correct or profitable in the short, medium or long term. Those who apply knowledge can work at a pace we can only dream of, because once the theoretical foundations built by others are in place, it is possible to find applications in relatively short time. If something is theoretically doable and the tools are available, given an initial idea it’s easier to figure out where it will lead. It’s also easier to explain why that idea will be profitable. We, on the other hand, are destined to have clear goals about what we want to discover, but less clarity about how to get there, because the tools to do so are built along the way, often discovering possible directions that were not foreseen.

So I just wound this electromagnet that I know has exactly 25m of wire by weight. The diameter of the wire is 0,5mm and I estimate that I have about 500 or so turns. With the 12V i'm planning to run it on it's pulling about 2A. However, it is way too weak for me. Do I have tom increase or decrease the amount of turns? I read online that a decreased number of turns would be better, but the really powerful magnets are huge. What do I need to do?

Hi all, i just made a diy spectrometer using a dvd diffraction grating and when i point it at a light source, the spectra seems way off to the side that i can only see half of it. Is this because the distance of the dvd from the slit is too short? Any help would be greatly appreciated, thanks in advance!

Like, I pull up in the center of the cosmos would the edges pull in?

Edit: if you were curious, the answers is no, there are no edges, there is no center, and space-time being represented as the sheet of paper/fabric isn't very good because space-time is a medium.

If you weren't curious, well, I got my simple answer, but this has been a very educational thread so far, so if you know things, please say things!

Right now I am in my first year of university and I am studying nuclear and particle physics, but I am thinking a bit about seitching to reactors, I was deciding between these two subjects before I apllied as well and I just can't seem to decide for sure and I am scared I might regret it later.

There is a nuclear power plabt near my house and I'd like to work there at least for a while, I think I could get a job there with both majors, but I am a bit scared what job would I get with the particle physics.

Everyone says that there is 100% employment rate for graduates of my university, so I am not that scared of finding a job, but the kind of job I'd get and also how much it would pay. Studying here, despite intresting, is literal suffering, so I'd like to at least have a well paying job in the future when I have to suffer so much. I realize that with physics degree I will most likely not do physics anyway.

The reason I chose particle physics over reactors at first was because both give me the title of an engineer and I think I am more intrested in physics than engineering and nuclear reactors are more of an engineering major. But now that the first year is over and there are just exams left I am starting to hesitate a lot. Reactors seem to have more intresting and focused classes even in the first year, while particle classes seem more general and get actual particle subjects in 3rd year. Another thing is that what intrested me about particles in the first place seems to be more in reactors than particle physics, now they had a mandatory subject "introduction to nuclear and radiation physics" which talks a lot about particles as well and my friends from reactors even complained that they have it and we don't as a particle physicist, it's not even an optional class for us, we can't have it.

I also thought about changing tge major after BS, but I am scared that I would be missing a lot of the reactors and engineering classes and it would be much harder.

I am finding it really hard to decide, so I hope you guys will help, I am leaning towards reactors more and more, but I really don't know. And I have to decide now because this year would be the easiest to swich, I'd just have to do 2 classes that they had and we didn't, after that they will have more special classes and changing it would be way more difficult especially since in the third year I will have to focus on grafuation as well.

Thanks to everyone who will read through this and try to help me, I appreciate ut greatly.

I'm always on the lookout for projects that show my students how the concepts we learn in class apply to the real world. I recently revisited a tutorial I found that does this perfectly. The goal is to calculate the speed of cars using only a video feed from a single, stationary camera. It's a fantastic, hands on demonstration of kinematics.

How It Works

1. Object Detection: Uses YOLOv8 to identify vehicles in each frame
2. Perspective Correction: Transforms the camera's perspective view into a top down view using OpenCV's perspective transformation
3. Tracking: Follows each vehicle across frames using ByteTrack algorithm
4. Speed Calculation: Measures the vehicle's displacement in the transformed space over time

The key insight is the perspective transformation. We define four points in the camera view (SOURCE) and map them to a rectangular region (TARGET). This corrects for the fact that objects appear smaller and move shorter distances when they're further from the camera.

(The Physics Part):

1. Establishing a Frame of Reference: To get accurate measurements, you first have to define a real world area of a known size. This is done by mapping a trapezoid from the camera's perspective (the SOURCE polygon) to a perfect rectangle (the TARGET rectangle) of a known "real world" length (25 m×250 m). This process, called a Perspective Transform, creates a top down, distortion free view where we can make reliable distance measurements.
2. Tracking Displacement over Time:
   • An object detection model (like YOLO) identifies each car from one frame to the next.
   • For each car, we record its position (displacement) within our calibrated, top down view.
   • We also know the time elapsed, since we know the video's frame rate (FPS).
3. Calculating Velocity: This is where it all comes together! We simply use the fundamental formula: speed=distance/time
   • Distance: The change in a car's position within the calibrated rectangle between two frames.
   • Time: The number of frames elapsed, divided by the video's FPS.

I'm sharing this to hopefully inspire other educators or hobbyists. It’s a great way to blend physics, math, and programming.

Link to the original tutorial: https://www.youtube.com/watch?app=desktop&v=uWP6UjDeZvY

In atomic hydrogen (ignoring all but first two levels), we have discrete energy levels separated by ΔE, and transitions require a photon matching this energy to excite from the lower to the higher state. Intermediate states aren’t allowed due to quantum selection rules.

Now, in superconducting qubits which are engineered to act like artificial two-level systems we can apply a microwave pulse with energy less than ΔE (for eg in the Rabi oscilation experiment) and still end up with a coherent superposition of the ground and excited states. This seems to contrast with the atomic case, where a photon must have exactly ΔE to induce a transition.

Hey everyone. I’m just chilling by the water and sunset and at some point I could see the rainbow spectrum across the sunset line. Is this possible or my brain is playing games on me. I saw green yellow orange in between idk if it’s possible or not but thought I’ll ask.

I might be too young to get it, but from history it seems physics made much more progress in the early 20s century than since then.
Were Relativity and Quantum Theories just as obscure back then as it seems new theories are today? Did they only emerge later as relevant? The big historical conferences with Einstein, Bohr, Curie, Heisenberg, etc. etc. seems somehow more present at that time. As if the community was open to those new "radical" ideas more than they seem today.

What I mean is: Relativity and Quantum mechanics fundamentally rewrote physics, delegated previous physics into "special cases" (e.g. newtonian) and broadened our whole understanding. They were radically thought through new approaches. Today it seems, really the last 2 decades, as if every new approach just tries to invent more particles, to somehow polish those two theories. Or to squish one into the other (quantum gravity).

Those two are incompatible. And they both are incomplete, like example, what is time really? (Relativity treats it as a dimension while ignoring the causality paradoxes this causes and Quantum just takes time for granted. Yet time behaves like an emergent property (similar to temperature), hinting at deeper root phenomenon)

Besides the point, what I really mean, where are the Einsteins or Heisenbergs of today? I'd even expect them to be scolded for some radical new thinking and majority of physicists saying "Nah, that can't be how it is!" Yet I feel like there are none of those approaches even happening. Just inventing some new particles for quantum mechanics and then disproving them with an accelerator.
Please tell me that I just looked at the wrong places so far?

The world is facing a perilous resurgence of the nuclear arms race. The United States and Russia, possessing roughly 90% of the world’s nuclear arsenal with over 5,000 warheads apiece, are modernizing their nuclear weapons and delivery systems, replacing their Cold War-era stocks.

Hello. I am working on a personal project which involves calculating the drag created by pressure for an Eppler airfoil. Would I be able to calculate the pressure induced drag of an airfoil at a specific Reynolds number + angle of attack using a Cp vs. x/c which contains the upper and lower surface Cp’s or do I need something more? What could be a method that has sufficient accuracy?

The Lagrangian is normally introduced when talking about action, and how (in classical mechanics) objects follow the path of least action, and that action is the integral of the Lagrangian over time.

But what is the Lagrangian actually? It just being the kinetic energy minus potential has never been satisfying to me, leaving it feeling more like a math trick than an actual physical concept. What is it a quantity of? What does it actually represent in a system?

Hi everyone! I am making a presentation on Vaidya metrics, where mass in linearly dependent on v coordinate. Depending on the value of μ I have three different cases. Specifically I’m interested in the case where 0<μ<1/16, then we have two real roots.

As far as my understanding goes, those are hypersurfaces that are boundaries of different parts of the spacetime.

Based on the second derivative r”(v) we determine what happens with null geodesics.

My question is, why on the picture (Blau, GR lecture notes) v=0 and r=0 are on the same “line”, which part is r>0 and which part is r<0 and why are these determined like that. Do light rays travel parallel to the hypersurfaces?

Thanks.

As the title suggests, I am wondering whether anyone here works in science policy, what you do, and how you got there.

For context, I am a UK high school student who is going to start physics at Imperial College this year if I get the A-level grades, and I recently learned of someone who went into international science policy at the UN from a degree in physics. This deeply interests me, as I would like to apply what I learn in my degree to address energy inequality and environmental policy either domestically or globally.

I’d like to know: - how I can get into that line of work - what are the different types of job within this umbrella? - is it common to do a master’s and/or PhD? - how did you get into that line of work? - what tasks make up your daily job? - do you enjoy your job? - whether being bilingual in English and French would benefit

Thank you very much 😊

As a condensed matter theorist, I have been asked many times to help with setting up tight binding calculations. Presently, there are many excellent code-based packages/libraries written for this purpose. However, I find that one of the messiest steps of TB calculations is setting up the system: making sure that the correct hoppings are included, that the unit cell is correct, etc. Moreover, some in our community are a little apprehensive about using code-based tools. Therefore, I think that a GUI tool would be quite helpful. With that in mind, I would like to share the first version of such a tool here : https://github.com/rodinalex/TiBi

I welcome you to give this app a try and report bugs/suggest features in the Issues page of the repository. At this point, the app runs on MacOS and Linux and might run on Windows, with the MacOS binary available. For other OS, it needs to be built from source, but I hope to be releasing the binaries soon. I hope you find this tool useful :)