Physics subreddits
We found 24 active physics subreddits: communities with at least one new post a day on average in September 2026, ranked by members. The largest is r/Physics with 3.25M members. The busiest is r/AskPhysics, with 1,284 posts last month. In 2 of the 19 we could measure, a brand-new account's post usually stays up: they remove 17% or fewer of posts from accounts under a week old.
Data for 24 communitiesDownload CSV
- r/Physics3.25M members
- r/AskPhysics1,284 posts in September 2026
- r/TheoreticalPhysics+48% members in 12 months
- r/Optics15% of new-account posts removed
All active physics subreddits, by members
| # | Subreddit | Members | Posts / month | Member growth, 12 mo | Median author age | Women | Posts with a reply | New-account posts removed | Links |
|---|---|---|---|---|---|---|---|---|---|
| 1 | r/Physics↗For physicists and physics students. See the rules before posting, and the subreddit wiki for common questions. Basic homework questions are not allowed. | 3.25M | 600 | +3% | 27 | 16% | 71% | 68% | Yes |
| 2 | r/AskPhysics↗Ask Physics | 1.57M | 1,284 | +5% | 28 | 16% | 77% | 37% | No |
| 3 | r/physicsmemes↗Description is left as an exercise for the reader. | 366K | 191 | +11% | 24 | 16% | 92% | 100% | Yes |
| 4 | r/astrophysics↗The branch of astronomy concerned with the physical nature of stars and other celestial bodies, and the application of the laws and theories of physics to the interpretation of astronomical observatio | 173K | 147 | +33% | 33 | 17% | 57% | Min. age/karma | Yes |
| 5 | r/PhysicsStudents↗A place for physics students of any level to discuss the intricate profoundness of the universe. | 149K | 553 | +23% | 22 | 24% | 86% | 40% | Yes |
| 6 | r/cosmology↗**/r/cosmology** - a community for questions, discussions, and articles about cosmology. | 144K | 63 | +20% | 34 | 14% | 60% | Min. age/karma | Yes |
| 7 | r/holofractal↗Exploring a connected universe through physics, geometry and consciousness. Centered on Nassim Haramein and collaborators' work on the quantum vacuum, holographic matter and spacememory, alongside Boh | 121K | 48 | +12% | 33 | 17% | 78% | Min. age/karma | Yes |
| 8 | r/QuantumComputing↗Academic discussion of all things quantum computing from hardware through algorithms. Not the place for business speculation, memes, or philosophy. | 103K | 196 | +26% | 27 | 14% | 50% | 95% | Yes |
| 9 | r/quantum↗Scientific discourse about quantum mechanics and related fields. Not for discussions about interpretations or speculative theories. | 93K | 132 | +27% | 29 | 15% | 47% | Min. age/karma | Yes |
| 10 | r/Radiation↗r/Radiation is your home on Reddit for discussing the science, careers , equipment and anything else related to ionizing radiation (alpha, beta, gamma, etc.) Do not post about non-ionizing radiation | 79K | 114 | +36% | 33 | 17% | 71% | 83% | Yes |
| 11 | r/QuantumPhysics↗A subreddit for discussing published work on quantum mechanics. | 72K | 80 | +13% | 29 | 18% | 67% | 30% | Yes |
| 12 | r/TheoreticalPhysics↗Post and discuss external content related to advanced research in physics. Remember to always back up your posts with reliable information, clear argumentation and verifiable sources. Professional o | 67K | 123 | +48% | 30 | 14% | 89% | Min. age/karma | Yes |
| 13 | r/NuclearPower↗Nuclear Power | 65K | 189 | +26% | 32 | 14% | 69% | 24% | Yes |
| 14 | r/CERN↗News and discussion about CERN, home of the Large Hadron Collider and birthplace of the World Wide Web. | 57K | 74 | +12% | 25 | 27% | 59% | 20% | Yes |
| 15 | r/CFD↗Computational Fluid Dynamics | 48K | 196 | +28% | 25 | 10% | 79% | Min. age/karma | Yes |
| 16 | r/Optics↗new-account friendlyA place for questions and discussions pertaining to optical science and optical engineering. | 30K | 144 | +28% | 30 | 16% | 77% | 15% | Yes |
| 17 | r/FluidMechanics↗Everything that is related to anything that flows. The hub for all the news, questions and mindblowing flow vizualizations! Official Lemmy community: https://discuss.tchncs.de/c/fluidmechanics | 29K | 72 | +40% | 28 | 11% | 61% | 26% | Yes |
| 18 | r/aerodynamics↗Aerodynamics, from Greek ἀήρ aero (air) + δυναμική (dynamics), is the branch of fluid mechanics which studies the motion of air, particularly when affected by a solid object. It is a core part of scie | 27K | 65 | +30% | 28 | 10% | 57% | – | Yes |
| 19 | r/HypotheticalPhysics↗Do you have a new hypothesis? Let us discuss it. Both laypeople and physics scholars are welcomed here. Let us discover together the possibilities of our multiverse. Remember, this sub is not an excus | 27K | 361 | +39% | 31 | 13% | 85% | Min. age/karma | Yes |
| 20 | r/learnphysics↗Learning about the universe | 23K | 134 | +108% | 27 | 17% | 36% | – | Yes |
| 21 | r/geophysics↗Geophysics | 12K | 39 | +21% | 29 | 23% | 70% | – | Yes |
| 22 | r/apphysics↗new-account friendlyThis subreddit will cater to anything related to Advanced Placement Physics (B or C) and prerequisite Physics classes. Asking questions, posting problems, discussing theories, and helping each other | 12K | 93 | +32% | 17 | 35% | 67% | 14% | Yes |
| 23 | r/Magnets↗Magnets! Post cool magnet things! Or ask magnet questions. We have a few experts here. Yes, we can answer the age old question. | 12K | 42 | +37% | 33 | 18% | 49% | – | Yes |
| 24 | r/AP_Physics↗AP Physics is a place for people to discuss the preparation for the AP Physics Exam. Stressed? Stuck? | 4.6K | 100 | – | 18 | 31% | 40% | – | Yes |
Looking for a ranking by size and growth? Top physics subreddits by tier.
How this list is built
Subreddits are grouped into topics by what their posts are about; this list holds the physics group. We include subreddits that are safe for work and had at least 30 new posts in September 2026, about one a day.
Members is Reddit's subscriber count; growth compares it with a year earlier. Posts with a reply is the share of posts that got at least one comment over the last three months. Median author age and women are estimated from what authors say about themselves, and shown only when enough of them did. New-account posts removed is the share of posts from accounts younger than 7 days that were removed; communities at or below 17% are marked new-account friendly. Min. age/karma means the subreddit asks for a minimum account age or karma before you can post.
The list is rebuilt every month from public Reddit posts and comments. Data and CSV are free to reuse under CC BY 4.0 with a link to this page.
Physics subreddits: common questions
What is the biggest physics subreddit?
r/Physics, with 3.25M members in September 2026. Next are r/AskPhysics (1.57M) and r/physicsmemes (366K).
Which physics subreddits are the most active?
By posts in September 2026: r/AskPhysics (1,284 posts), r/Physics (600 posts) and r/PhysicsStudents (553 posts).
Which physics subreddits can a new account post in?
r/Optics (15% of new-account posts removed) and r/apphysics (14% of new-account posts removed). They ask for no minimum karma or account age, and most posts from accounts under a week old stay up.
How often is this list updated?
Every month, when we rebuild our subreddit data. This version uses data for September 2026. Member counts come from Reddit; activity, removals and who writes come from public Reddit posts and comments.
Find the subreddits that fit your post
This list is the same for everyone. Find Subs narrows it to communities your account can post in, where your audience writes, and tells you when to post.