About r/AskPhysics
Community guide
r/AskPhysics is #669 in our SFW Top 1000 (about 1.6 million subscribers). A recent sample averaged 39 posts a day (~89% text, ~11% link). Its public rules include: Irrelevance; Rudeness; No cheating on schoolwork, and show your own attempt; Questions that went unanswered for a day; No AI/LLM drivel.
What belongs here
Stay inside the room’s stated scope rather than adjacent off-topic dumps. Match posts to: Irrelevance; Rudeness; No cheating on schoolwork, and show your own attempt; Questions that went unanswered for a day.
How it differs from lookalikes
Prefer this room when your post matches its description and rule list—not merely a larger sibling community.
Practical pointers
Read the live sidebar/rules before posting; rules can change.
The community was created on Sep 8, 2011, which makes it 15 years old. Since Nov 2, 2026, it has gained 1,067 subscribers (+0.07%). Among the 7 communities on our physics list it is number 2 by size. It sits just behind r/Hulu (#667) and ahead of r/wholesomeanimemes (#669) in our ranking.
What sets r/AskPhysics apart
Compared with other large communities, r/AskPhysics leans heavily on text posts (89% of recent posts; the typical Top 100 subreddit sits at 35%). Its rhythm is strongly tied to time zones: the busiest hour (17:00 UTC) sees about 4.5× as many posts as the quietest (05:00 UTC).
Subscriber growth
Between Sep 19, 2026 and Nov 9, 2026, r/AskPhysics climbed from 1,568,713 to 1,576,646 subscribers (+7.9K, +0.51%). That is about 156 new members per day. The chart shows 10 weekly subscriber counts.
Top posts on r/AskPhysics this week
The most upvoted posts of the past seven days, in the order Reddit ranks them (collected Nov 7, 2026).
- If 0 is ‘no physics has been realised’, and 100 is ‘all possible physics theories have been proven’, where do you think humanity stands today?u/androgenousdonut · Nov 2 · text post
- Is it theoretically possible to sharpen a standard chef's knife so finely that gravity alone, working with the weight of the knife, would be enough force to slice a block of cheddar cheese?u/IndigoJones13 · Nov 1 · text post
- If you had an antimatter Sun and launched it at the real Sun from outside the solar system, would it even reach the Sun or would it just annihilate off the solar wind, interplanetary medium and other…u/Anthoniyuuuuuuu · Nov 4 · text post
- Why does a longer barrel allow a bullet to travel farther?u/PaulsRedditUsername · Nov 2 · text post
- Theoretical upper bound on temperature?u/DarthCloakedGuy · Nov 2 · text post
- If electrical energy travels through electromagnetic fields around the wires, what exactly do the wires do, and why are they needed to power a light bulb?u/No_Woodpecker6948 · Nov 5 · text post
- What if the universe has no objective "present"?u/leadattttt · Nov 3 · text post
- Is there any reason why gravity attracts object and not repel?u/Single_Flower_5994 · Nov 5 · text post
- Why can't you accelerate out of a Black Hole?u/Mutated_zombiebush · Nov 4 · text post
- Is General Relativity a simplified model?u/samgrep · Nov 2 · text post
All-time top posts
The highest-ranked posts in the history of r/AskPhysics, from 2020 to 2026, ranked by Reddit.
- I'm a physics teacher and I can't answer this student questionu/there_is_no_spoon1 · Jan 25, 2024 · text post
- My advice to all youngsters: Don't spend your years at high school trying to get ahead for universityu/mcroobie · Sep 16, 2020 · text post
- Since gravity moves at the speed of light, does the Earth orbit where the sun was 8 minutes ago?u/Interesting_Cloud670 · Mar 24, 2025 · text post
- I inherited my late father’s unfinished physics work on dark matter. How should I responsibly handle it?Feb 5, 2026 · text post
- Why isn’t Hiroshima currently a desolate place like Chernobyl?u/Pandagineer · Jan 30, 2024 · text post
- Einstein is a popular example of a genius. Yet, polymaths like Gauss, Euler, Hamilton, Van Neumann seem far more formidable. Is it just that relativity is remarkable, or am I just impressed by major …u/michaeldain · Oct 7, 2026 · text post
- Why is the speed of light 299,792,458 m/s?u/Orneb · Nov 21, 2024 · text post
- HELP!. My 9 year old daughter asks: "WHY does gravity exist?"u/DrMerkwuerdigliebe_ · May 13, 2025 · text post
- I have a friend who does not believe in the force of gravity, merely thinking that everything 'heavier than air' is supposed to fall down. How do I scientifically disprove this?u/Hollow_Knight999 · Aug 6, 2024 · text post
- If an ant hits you going 100,000,000 mph, what would happen?u/Available_Ad_7263 · Feb 22, 2025 · text post
What r/AskPhysics talks about
Across 266 recent posts (Oct 29–Nov 5), the words that come up most are “physics”, “energy”, “universe”, “light” and “question”. Other frequent themes are space, quantum, actually, theory, earth and black. Recurring phrases include “black hole”, “dark energy”, “solar wind” and “wind interplanetary”. By format, 89% are text posts and 11% are links.
Activity and best time to post
r/AskPhysics gets about 39 new posts a day. The public archive holds 192,876 posts and 1,755,112 comments in total, about 9.1 comments per post. Last week the busiest day was Thursday (55 posts) and the quietest was Saturday (21). Posting peaks around 17:00 UTC and is lowest around 05:00 UTC.
Rules of r/AskPhysics
The moderators of r/AskPhysics list 5 rules. In short:
- Irrelevance
- Rudeness
- No cheating on schoolwork, and show your own attempt
- Questions that went unanswered for a day
- No AI/LLM drivel
How to join
Open reddit.com/r/AskPhysics and press “Join”. Read the community rules in the sidebar before you post: every subreddit is run by its own volunteer moderators.
Frequently asked questions
How many subscribers does r/AskPhysics have?
r/AskPhysics has 1,576,646 subscribers (Nov 9, 2026), which makes it the #668 safe-for-work subreddit in the SubMouse ranking. It added 7,933 members between Sep 19, 2026 and Nov 9, 2026.
When was r/AskPhysics created?
r/AskPhysics was created on Sep 8, 2011, so it has been around for 15 years. The oldest post in the public archive is from Oct 19, 2011.
Is r/AskPhysics still active?
Yes. r/AskPhysics gets about 39 new posts a day (average of the last four weeks). Over its lifetime the archive counts 192,876 posts and 1,755,112 comments. In a sample of 266 recent posts we counted 231 different authors.
What is the best time to post in r/AskPhysics?
Based on post counts from Oct 29, 2026 to Nov 4, 2026, the busiest day was Thursday and the quietest Saturday, and most posts arrive around 17:00 UTC, with the fewest around 05:00 UTC. More posts also means more competition, so a quieter hour can help a post get noticed.
What kind of posts are on r/AskPhysics?
The community describes itself as: “Ask Physics” Recent post titles often mention physics, energy, universe, light and question. Most posts are text posts (89%).
Is r/AskPhysics SFW?
Yes. Reddit does not mark r/AskPhysics as an 18+ (NSFW) community. SubMouse lists safe-for-work subreddits only.
What are the rules of r/AskPhysics?
Join the community on Reddit first, then use “Create post”. r/AskPhysics accepts text posts only, with galleries enabled. It has 5 posted rules, starting with: “Irrelevance”; “Rudeness”; “No cheating on schoolwork, and show your own attempt”. Moderators remove posts that break the rules, so read them in the sidebar before posting.
What subreddits are similar to r/AskPhysics?
Communities with similar topics include r/Physics (3.3M), r/AskReddit (60.1M), r/ask (1.3M), r/AskCulinary (1.3M) and r/AskEurope (1.7M).
Stats from public data (data updated Nov 9, 2026; activity, rules and archive totals via the Arctic Shift archive, Nov 6, 2026; top posts from Reddit’s public feeds). Point and comment counts are archive snapshots and can be lower than on Reddit today. SubMouse is an independent directory and is not affiliated with Reddit or the moderators of r/AskPhysics.