Clem Tillier
@ctillier.bsky.social
eclectic interests - space science & tech, SF Bay Area transit, HSR, anything on rails 🚄 or on a rocket 🚀
Now out! Part 2 on the Geary metro, discussing its East Bay connection, downtown alignment, and yard location.
Geary metro, purpose-built for SF
Part 2: East Bay connection, downtown alignment, and the yard
medium.com
Infrastructure Weak@infrastructureweak.bsky.social · 2mo agoI've just published this article, Part 1 of 4 about the choices that will enable San Francisco to finally build a Geary metro. medium.com/@infrastruct...
Umberto Boccioni’s “Unique Forms of Continuity in Space.” I had to walk around it three times to understand how it moved without motion. en.wikipedia.org/wiki/Unique_...
Unique Forms of Continuity in Space - Wikipedia
en.wikipedia.org
Jodi Pickens 🏳️🌈🖖✨@jodipickens.bsky.social · 2mo agoArt question 🎨 What painting, photograph, sculpture, or piece of visual art has stayed with you long after you first saw it? Not necessarily your favorite. The one that lingered.
One of the neatest observations made by lightning mappers: we clocked this meteor fireball at ~57 kilometers per second (125,000 mph). That is FAST!
Multi-sensor Observations of a High-velocity Fireball over the South Atlantic on 2026 April 1
Multi-sensor Observations of a High-velocity Fireball over the South Atlantic on 2026 April 1, Silber, Elizabeth A., Rubbrecht, Niels, Tillier, Clemens E., Cano, Juan L., Landis, Rob R., Longenbaugh, ...
doi.org
This nicely explains why SpaceX valuation is unmoored from the laws of thermodynamics. Cooling GPUs without conduction or convection is not the “no brainer” they claim.
Climate News@climatenews.bsky.social · 2mo agoRead IEEE Spectrum's article on orbital data centers by Andrew Cavalier: spectrum.ieee.org/orbital-data...
New on the blog: how @caltrain.com could accomplish level boarding soon, fast and cheap. This is their most important capital project.
Level Boarding Soon, Fast, and Cheap
Caltrain is working on their level boarding roadmap. If their recent work on grade separations is anything to go by, the capture of the age...
caltrain-hsr.blogspot.com
I spent the last month obsessed with finding colors that can't be displayed on a conventional screen. This is what I found. moultano.wordpress.com/2026/06/19/w...
Where to Find the Colors Your Screen Can’t Show You
An atlas of the vibrance of the real world
moultano.wordpress.com
On weekends, I like how you can use Caltrain like a horizontal elevator, just push a city’s button and whoosh, there you are, ding!
A bolide exploded high above New England in Earth's atmosphere on Saturday afternoon, creating a loud booming noise that was heard across the region. The flash of the exploding meteor was detected from the GOES-19 weather satellite's GLM instrument.
Progress! The more I work on this, I’m thinking it will be a shame to cover it with the road deck. Maybe a transparent deck? During construction, the girder seen here was painted with giant letters “McClintic Marshall,” the name of one of the steel suppliers. Thought about it, but it’s too cryptic.
Oil and gas might go the way of whale blubber sooner than we think!
David Roberts@volts.wtf · 4mo agoGrid-scale batteries are going in an absolutely wild pace. Every whingey objection to renewables you've ever heard is basically solved by batteries. This is happening whether any of the hopeless dipshits running the US want it or not.
"the dramatic cost declines in batteries have now made 'firm renewables' — solar or wind paired with batteries — cheaper than fossil fuels in many parts of the world." This is game changing.
Solar plus batteries cheaper than gas — IRENA report - Gas Outlook
A new IRENA report finds that 24/7 “firm” clean energy is cheaper than coal and gas in many parts of the world.
gasoutlook.com
This is a brilliant way to think about infrastructure: “for every obstacle encountered: is this a rock, or is this a person?”
Jonathan English@englishrail.bsky.social · 4mo agoInfrastructure projects routinely spend billions of dollars to avoid difficult conversations. I wrote a new piece on Infrastory on how we need to be better at recognizing the problems that can be solved with a phone call rather than big infrastructure. open.substack.com/pub/infrasto...
After mixing up a fresh batch of International Orange (not a standard Tamiya color) this subassembly is almost ready to install on the bridge tower.
GLM has been game-changing for the community that monitors meteors. Great example! It’s also one of the many new capabilities that would be lost in the current plan to stop flying a GLM-like instrument after the current fleet reaches end of life.
Dakota Smith@weatherdak.bsky.social · 6mo agoThe loud boom heard in Cleveland and the light seen across the Midwest and Mid-Atlantic... it was a meteor! GOES-19's geostationary lightning mapper picked up the brief flash of light.
Reverend Jesse Jackson called on each of us to be heralds of change, to be messengers of hope; to step forward and say “Send me” wherever we have a chance to make an impact. How fortunate we were that Jesse Jackson answered that call. What a great debt we owe to him.
How to identify American fascists as stated by our own US government in March of 1945.
@jeffwise.bsky.social watching your vids, it bugs me that you assume mh370 was in a pristine state (no malfunctions.) This underpins the idea that the sequence of events was weird. It is only weird for a pristine system that behaves according to docs & design intent, which damaged systems may not!
🚨🔥 Warmest Christmas on record for the Contiguous U.S.! The average high of 57.9F and the average low of 36.6F each broke the Christmas record by a full 3F. 🔥🚨
New blog post by @ctillier.bsky.social. I'd be curious to learn more about proposal #4 for improving trip time, modular/quick-build platform height increases, and about comparable examples.
It's the Trip Time, Stupid
Components of trip time. Electrification only improved time in motion. Photos by Mliu92, Evan0512, SaarPro. Marco Chitti recently penned a g...
caltrain-hsr.blogspot.com
From the hang time (~10 seconds from apex to ground), looks like this fountain is almost 500 meters high. Easily clears Eiffel Tower.
Alex Spahn 🌋🌪️☄️@spahn711.bsky.social · 9mo agoThis is U N B E L I E V A B L E. #Kilauea
California shut down its last coal plant last week and nobody even noticed, it made so little little difference. Meanwhile solar is up 17% and gas is down 17% from 2024. I have a few highlights... www.climatecoloredgoggles.com/p/ding-dong-...
Ding dong, coal is dead
At least in California.
climatecoloredgoggles.com
Alrighty, ready to see something really cool? (and maybe a little nauseating) The evolution of Hurricane Melissa's mesovortices at peak strength.
A display of pure power from Hurricane Melissa today. Remarkable satellite imagery.
It’s Sunday and I’m trying to catch an 8-minute connection from BART to Caltrain at Millbrae. BART arrived on time at SFO but departed 7 minutes late for Millbrae. Will there be enough time for the time-honored Millbrae escalator sprint?