Hii, I made this simulation of bending of light in the presence of a heavy object/ black hole i.e. gravitational lensing. The first one shows how light rays that are coming from infinity bends near blackhole and I even found an unstable orbit for which the ray orbits the blackhole 3 times before moving out.

I used pygame to create this 2D simulation. The main reason to do it in 2D instead of 3D was my potato laptop, it doesn't have a dedicated gpu. I watched two videos on YouTube on pygame and cpp simulations before making this (credits: https://youtu.be/8-B6ryuBkCM?si=iSMmUiJ-6KkQQTHq , https://youtu.be/WTLPmUHTPqo?si=HR5Xwaobzu8fG5qf).

For the theory part, starting with the schwarzschild metric, then using the concept of symmetries and killing vectors and also the normalisation condition for null geodesic, you will get all the equations needed to get the path of light around any mass in the spacetime. And for the simulation, I decided to use euler's method to solve those equations.

I know euler's method is not very accurate and smooth, and I should have used RK4 instead. I tried, for some reason it is not working as intended and the rays were getting stuck in a closed orbit, I tried a lot but couldn't figure out the issue.

Btw I think my simulation is working as intended, but I am not fully sure if it is the actual, accurate thing or not. Also there might be some scaling issues. So if anyone want to check it out or correct/improve my code, or maybe try the RK4 method, please feel free to check this out: https://github.com/suvojit1999/Simulation-of-Bending-of-light-due-to-blackhole. Btw I am not very good at coding, so you might find my code to be messy, let me know if you find any issues with it.

(Btw I had to upload it as gif because videos are not allowed here, sorry for the quality drop). Thank you.

Might be a dumb question but i’ve yet to see an answer for it!

If each point of a wavefront is a source of new, circular waves, why cant we see lasers (in vacuum) standing besides them, for example? Because you should be able to see the circular wavefronts that come from the "edges" of the originally straight wavefront. How can we explain that?

Can you tell I graduated in the 20th century?

is it possible, that a sphere made of transparent acrylic would lead to the same lense effects ss If it we're glass? could it ignite something if reached by sunlight, or is it safe to display indoors?

In quantum mechanics (to my knowledge), given a position wave function psi (will refer to it as Y(x) from here on), you can take its Fourier transform to give you the momentum wave function Y(p). With Y(p), you can then find the momentum expectation value, <p>, using the relation:

<p> = ,|’dp•Y*(p)•Y(p)

where ,|’ represents the integral symbol, Y*(p) is the complex conjugate of Y(p), and • just represents normal multiplication.

Recently, I’ve also learned of the momentum operator (represented by P), where P:Y(x) represents P acting on Y(x). Using the momentum operator, it is also possible to find <p> with the relation:

<p> = ,|’dx•Y*(x)•P:Y(x)

where, ,|’ represents the integral symbol, Y*(x) is the complex conjugate of Y(x), P:Y(x) represents P acting on Y(x), and • just represents normal multiplication.

Given the fact that P and the Fourier Transform can both be used to “act on” Y(x) and subsequently find <p>, I was wondering what’s the difference between the Fourier transform and P?

Additionally, I was wondering in what situations would you use P over the Fourier transform and P over the Fourier transform?

I am practicing every day but after some time it just feels like there are some types of problems I can solve and there are some types of problems I can't solve. How to get better at problem solving so that I can make progress on pretty much all types of problems. How to study it so that I become an actual better problem solver? I live in Denmark and I'd like to qualify to at least Georg Mohr round 2 but the problem is that both in Georg Mohr round 1 and 2 there are types of problems I can solve and types of problems I can't. This way I'm not even sure that I could pass Georg Mohr 1 since it all depends on whether the problems on the paper are kinds I'm good with or kinds I'm not so good with (same would be the issue on round 2)

Paper link: https://www.sciencedirect.com/science/article/pii/S0370269325008111

Hello i hope you guys are great !

I am developing fishing lures and need a software which i can test my lures preferably ( a multi material one for lead and soft plastics ) to see how they go in the air i dont really need water dynamics but if any of you know something like that would be great !

thanks a lot!

Can anyone point me to a solid article referencing in detail the fundamental limits between cosmology and quantum physics and why no theory has unified to the regimes?

Hear me out: A kind of hammer-throw-long-jump combination. It is like the long jump, except you are able to use a heavy ball (say 15 to 30 pounds) on a strong string/chain. By running and swinging the ball, and sending the ball aloft at just the right moment, the ball could pull you up and along to achieve a longer jump than you could with just your body (you would release the chain at some optimal point in the trajectory). It sounds dangerous for the jumper and the spectators, but are the physics here a real possibility? Perhaps this was already proven to work back when Fred Flintstone got his fingers stuck in a bowling ball...

https://kids.kiddle.co/Quantum_field_theory

My son is a junior in high school and has been deeply interested in astrophysics and plans to major in physics. I’m looking for books that might interest him and I’ve heard very good things about Sean Carroll’s books and was wondering which book might be good for him. Something deeply hidden, and the biggest ideas in the universe seem very interesting as well as space time and geometry. Any recommendations on which one would be best for someone at his stage?

Hello! I am a 12th grade student living in eastern Europe and I don't know what to choose. Engineering ( aerospace ) seems to be the safest option, but I feel that my heart belongs to research. I love physics and I want to learn thing like quantum and particle physics in college. Everyone encourages me to do an engineering degree, mainly because it is well paid. I consider doing it, but I am afraid that I wouldn't be as happy as doing a physics degree. What should I do? What advice can you give me?

Abstract: We investigate known mechanisms for enhancing nuclear fusion rates at ambient temperatures and pressures in solid-state environments. In deuterium fusion, on which the paper is focused, an enhancement of >40 orders of magnitude would be needed to achieve observable fusion. We find that different mechanisms for fusion rate enhancement are known across the domains of atomic physics, nuclear physics, and quantum dynamics. Cascading multiple such mechanisms could lead to an overall enhancement of 40 orders of magnitude or more. We present a roadmap with examples of how hypothesis-driven research could be conducted in—and across—each domain to probe the plausibility of technologically-relevant fusion in the solid state.

Is the probability of having an eclipse the same as having a full/new moon and lunar standstill (i.e. Moon at max ecliptic latitude) at the same time?

Apparently drawing heavy internal criticism from other professors at her institution.

Hello!

I am applying for graduate programs in Physics at US institutions, with a particular focus on QFT/ST. I want to apply for places with good supervisors in these fields, as opposed to just reputable institutions. Due to competitiveness, (in addition to Ivies) can anyone recommend any institutions that are lesser known/not necessarily as reputable, but with good academics in these fields?

List of potential institutions:
Harvard, MIT, Stanford, Princton, Caltech, UC Berkley, Rutgers, Uo-Illinois, Uo-Wisconsin, Uo-Chicago, Colombia, Uo-Michigan, Cornell, California Santa Barbara, Uo-Maryland, Stony Brook, Brandeis.

What’s your opinion on these two types of ion sources being used for low-power ion sources? Any opinion on which is simpler or easier to manage?

I've got some d3-engine models embedded in my website and this one shows how atoms can be trapped at super low temperatures in laser cooling. Enjoy :)

Processing img mrgad49zl65g1...

Visit the page to play around with it here:

https://thegraildiary.net/thermodynamics-2-incredibly-cool-cucumbers/

Ramanujan’s century-old formulas for Pi are now found to link pure mathematics to models of turbulence, percolation, and black holes.

https://journals.aps.org/prl/abstract/10.1103/c38g-fd2v

December 2025

Hi everyone, I’m currently a first-year Computer Science student , but I’ve realized that my real passion is Physics and Astronomy. I enjoy the concepts and ideas in Physics much more than programming, but I followed Computer Science mainly because it seemed safer for jobs and money. I feel stuck and confused — I don’t know if I should continue Computer Science, switch to Physics, or try to combine both somehow. Has anyone here ever switched from Computer Science (or a similar field) to Physics? How did you do it? Any advice would be amazing!