Show HN: Newton's Orchard – Browser-based space/gravity playground https://ift.tt/mlkdS1M

Show HN: Newton's Orchard – Browser-based space/gravity playground Hi HN! My son spent a lot of time in 5th grade playing with the 2-dimensional PhET gravity/space sims[1]. His STEM class uses it, and he was playing with it at home, and has been looking for more. I found several space sims/playgrounds online, including NASA's Eyes on the Solar System[2], but nothing that seemed to offer a real progression from what he was getting out of the PhET sims, so I built Newton's Orchard over the summer for him. https://ift.tt/g0LIwiT The source is also published at https://ift.tt/SiPt07a It features deterministic time scrubbing, all bodies are editable, different preset systems and experiments, missions to complete (complete 3 to unlock the blackhole object type and mission), and a gallery for user submissions. I would very much appreciate feedback from HN - particularly from the lens of making it engaging and illuminating for students, and anyone that would like to just get a feel for how gravity works. Thank you! [1] https://ift.tt/WSpqDP2... [2] https://ift.tt/I4lrZqR https://ift.tt/g0LIwiT September 1, 2026 at 10:13PM

Show HN: Mcptunnels – ngrok for MCP with basic OAuth https://ift.tt/JC37OTS

Show HN: Mcptunnels – ngrok for MCP with basic OAuth Basically, OpenAI tunneling sucks and is broken most of the time. This can get you tunneling pretty trivially to share with someone temporarily. Roadmap includes being able to host MCP servers trivially as well. https://terragohan.github.io/mcptunnels/ September 2, 2026 at 02:04AM

Show HN: Semantic Overlays – an NX bit for LLM prompt injection (live demo) https://ift.tt/t6O27pu

Show HN: Semantic Overlays – an NX bit for LLM prompt injection (live demo) I've built a new method for steering LLMs called Semantic Overlays, small trained adapters on a frozen model which change how it perceives a piece of its context. The most readily applicable usage is to mitigate prompt injection, and it lets us take a very-injectable Qwen-3.5-9B to SOTA scores on all the prompt injection benchmarks I could find. (They are only blackbox attacks, but I did NOT train on anything like them — whitebox attacks are out of scope for this paper) I'm excited for you to play with the tech — see if YOU can break it! (let me know if you can) Paper at https://ift.tt/BAFRDpZ if you want to read more about it, code at https://ift.tt/EWKauSN , adapters at https://ift.tt/3zNdyMC... Also https://ift.tt/jKtpiJI if you wanna watch a little video I made! https://semantic-overlays.vercel.app/ September 1, 2026 at 11:10PM

Show HN: Guess the AI model from its web design https://ift.tt/cQp81Lx

Show HN: Guess the AI model from its web design https://ift.tt/rSuHnR3 September 1, 2026 at 01:10AM

An Operator's Perspective on How Muni Moves and Connects People

An Operator's Perspective on How Muni Moves and Connects People
By

Sincere Dow steps out of the operator chair to strike a pose on a Muni train. For Muni Operator Sincere Dow, no two days on the job are quite the same. “I pretty much float and drive all the train lines,” she said. “But mainly I am on the F Market. And I also do the J Church a lot.” Dow’s work takes her through unique neighborhoods and by some of San Francisco’s most iconic destinations. There also are schools on some of her lines. And she loves helping students get where they need to go. “They’re all very grateful,” Dow said. “They’re especially appreciative when you take that extra time to...

Published 2026-08-31T00:00:00Z
https://ift.tt/9gW8tSJ

Show HN: Corporate Mind Games – logic puzzles with a sarcastic corporate theme https://ift.tt/MVtLsgI

Show HN: Corporate Mind Games – logic puzzles with a sarcastic corporate theme I have always enjoyed building and playing puzzles. I am a regular user of NYT Games and LinkedIn Games. I thought it would be fun to create some corporate-themed puzzles as a silly alternative to LinkedIn Games. So, I built Corporate Mind Games. The games are intended to be a little bit sassy and sarcastic, but I hope they are enjoyable and challenging. I was planning to post this on HN last week. However, many years ago, I made a game called Don't Wordle, which unexpectedly appeared on the front page last week. I ended up getting distracted by that, and I also figured it was more appropriate to post this game on HN on a Monday morning given the theme. So here we are. https://ift.tt/mW245wC August 31, 2026 at 09:38PM

Show HN: NFC Energy-Harvesting PCB Business Card with an MCU https://ift.tt/vTjbn16

Show HN: NFC Energy-Harvesting PCB Business Card with an MCU https://ift.tt/Rlwcu69 August 28, 2026 at 07:18PM