Riley Rainey

Skydiving the eclipse - during totality near Dallas. Ineffable. 🎥 Riley Rainey

@AJamesMcCarthy Wow. Impressive!

Here’s a stabilized live view of the ISS through my telescope and the photo I made from stacking the image frames. The hardest part was getting my telescope to track it smoothly as it whizzed through the sky

@drxwilhelm @grok Welp, there is it. OK, there went the rest of my weekend ...

@rileyrainey @grok Quaternions in engineering kept the structure alive while academia went vector-only. Hestenes' STA picks the thread back up if you want a modern starting point.

✂️ The cross product only works in three dimensions. Heaviside built all of electromagnetism on it anyway. In 4D spacetime there is no unique perpendicular direction to pick, so the cross product has no natural extension. Heaviside's vector calculus cannot be written down in a Lorentz-covariant form without outside help. The algebra that does extend is geometric (Clifford) algebra. In 4D spacetime algebra, Maxwell's four equations collapse to one: ∇F = J. 𝐄 and 𝐁 become a single bivector. Charge and current become one four-vector. The structure was there the whole time. Heaviside replaced Maxwell's quaternion formulation with 3D vectors in 1884. Minkowski recast the equations in spacetime tensor form 24 years later. Neither reached for the geometric algebra that would have made the structure visible in one stroke. Hestenes did, in the 1960s. Most physicists still haven't met it. The 3D shortcut cost a generation.

@newstart_2024 *posted as a short form video*

Elon Musk was asked: “What’s one invention that’s made us worse, not better?” His answer: short-form video. He called it straight-up “brain rot.” And he’s not wrong. A local news report highlighted how kids are getting flooded with dopamine hits every 15–30 seconds from YouTube Shorts and TikTok-style content. Brain scans show overactivation in the reward centers, which over time trains the brain to crave instant gratification, shortens attention spans, and contributes to attention problems, behavioral issues, and even emotional dysregulation. Doctors are now seeing cases where it’s hard to tell the difference between true ADHD and what they’re calling “environmental ADHD” caused by excessive screen use. 78–84% of kids aged 2–12 are on YouTube, often for 2+ hours a day. This one feels especially urgent for parents. How much short-form video are your kids (or you) consuming daily — and have you noticed any real impact on attention span or mood?

@MikeLevin @grok is there any scientific documentation that the Atlantic Conveyor / Gulf Stream has ever collapsed previously?

This should be a bigger story.  Scientists are more concerned than ever that a critical Atlantic current will collapse soon and wreak havoc on North America and Europe. The Atlantic Meridional Overturning Circulation, or AMOC, is a massive conveyor belt of ocean currents that transports water from the tropics to the Atlantic.  Without it, severe weather would impact both regions at potentially devastating rates. These scientists aren't just warning us about an environmental issue—they're sounding the alarm about a climate threat that could fundamentally rewrite how future generations survive on our planet. theguardian.com/environment/20…

@drxwilhelm @grok Thank you! I spent a fair part of my career applying quaternions in engineering simulations. Interested this more generalized math topic.

For the GA / Clifford route that handles 4D natively: Doran and Lasenby's "Geometric Algebra for Physicists" is the standard text. Hestenes' "Spacetime Algebra" is the original. My paper covers the cross-product limitation directly if you want the compressed version with the EED-specific argument.

@luismbat MIT deserves the credit for making the source code available. Plus the amazingly tireless volunteer efforts of many folks - Ron Burkey, in particular - much less so NASA

NASA open sourced the Apollo 11 codebase: github.com/chrislgarry/Ap…

@VinnyMartorano Highly suspect. And there is no free lunch here: A sufficiently efficient atmospheric water extractor would also reduce rainfall.

An up and coming technology system could help restore Central Texas ground water levels by pulling water from the air. It's called Atmospheric Water Generation. The system condenses water vapor into an ultrapure source of water that can be used for your home, or on a large scale, meet the needs of an AI data center. CEO of Texas BlueWater Renewables, Barbara Canales, says the systems can last 20-30 years, and would help preserve much needed ground/surface water. Full report from Greater Edwards Aquifer Alliance: aquiferalliance.org/atmospheric-wa… @cbsaustin

@AJamesMcCarthy beautiful. thank you!

I threw some free downloads on my website to celebrate humanity's new distance record! You can grab them at the link in my bio. They're cut from the full res image files, super high quality. Celebrate Artemis with the rocket that got them there!

@blind_via Several of my designs go skydiving with me and I haven’t had one fail during the opening shock yet.

Can your PCB survive many G loads during space launch?

@LuciaBlick And, LLMs can explain code as well as write new stuff. I suppose blank pieces of paper are always more intriguing.

Allow me some shit posting today... dedicated to the newly empowered vibe coders who will someday have to support their refactors :)

Post a picture YOU took. Just a pic. No description.

@ElectronicsbyJH Happy to experiment on this with you. It generates C modules from the model. github.com/rrainey/obliq-2

Yea I need to convert this to python, I really don't want to use MATLAB/Simulink tbh

@grok @sleitnick What's old is new. I happened to have implemented PNG-based AAM's in an open source flight sim I released in 1991. gnu.org/software/acm/ - it still runs on a few Linux distros if you want to look at the code in action.

Proportional Navigation Guidance (PNG) is a homing missile technique where the missile turns at a rate proportional to the line-of-sight (LOS) rotation rate to the target. Command: lateral accel = N × closing velocity × LOS rate (N usually 3-5). If the target drifts across your view, you bank to match that spin proportionally. This zeros the LOS rate and leads to perfect intercept (assuming constant speeds/no jinks). In your quadratic demo, you're solving the exact future hit point upfront. PNG is simpler feedback—no algebra per frame, just reactive control. Both make killer gamedev examples!

You can use the quadratic formula to make homing missiles properly lead and hit their target. I've used this in games for like a decade. I wish they'd use examples like that in math class. Give practical/fun examples. I hated math b/c it was too abstract. Gamedev made it fun.

@DanCleary79 Move along. Americans do not put slashes on the number "7".

Here’s the slowed down “Roswell footage“ from the new Disclosure Day trailer. The slate says “#5 Occupant” and it’s from “Roll 18”. It would be awesome if that was based on real footage. Or… maybe it IS real footage. (Nahhhh… right?)

@cqcqcqdx Um, no

Data from a damaged or unreadable Micro SD card may be recovered by manually wiring its essential pins and accessing it through USB connections, bypassing the normal card reader interface.

@Rafael_L_Spring Simulation is hard.

> Builds "sensor fusion engine" to "solve the drift problem" > Uses ground truth in solution > Gets 1.6k likes > smdh.jpg

@beffjezos @michaelandregg Simulation is not instantiation.

Can you feel the acceleration? Brain uploading is now real. Huge congrats to @michaelandregg & team

@NRO_gov Or, the satellite's path just matches the gravity-warped space around the planet in a way that makes it look like it's "orbiting". Ask Mercury.

It is a balance of forces. A satellite’s forward velocity moves it ahead while Earth’s gravity pulls it inward. When those forces are aligned, the satellite follows a stable path around the planet.