TauZero @ TauZero @mander.xyz 帖子 12评论 362加入于 2 yr. ago
Then you'd be surprised when you calculate the numbers!
A Falcon 9 delivers 13100kg to LEO and has 395,700kg propellant in 1st stage and 92,670kg in 2nd stage. Propellant in both is LOX/RP-1. RP-1 is basically long chains of CH2, so together they burn as:
3 O2 (3x32) + 2 CH2 (2x14) -> 2 CO2 (2x44) + 2 H2O (2x18)
Which is 2*44/(2*44+2*18) = 71% CO2. Meaning each launch makes (395700+92670)*.71 = 347 tons CO2 or 347/13.1 = 26.5 tons of CO2 per ton to orbit. A lot of it is burned in space, but I'm guessing the exhaust gases don't reach escape velocity so they all end up in the atmosphere anyway.
As for how much a compute satellite weighs, there is a wider range of possibilities, since they don't exist yet. This is China launching a test version of one, but it's not yet an artifact optimized for compute per watt per kilogram that we'd imagine a supercomputer to be.
I like to imagine something like a gaming PC strapped to a portable solar panel, a true cubesat :). On online shopping I currently see a fancy gaming PC at 12.7kg with 650W, and a 600W solar panel at 12.5kg. Strap them together with duct tape, and it's 1000/(12.7+12.5)*600 = 24kW of compute power per ton to orbit.
Something more real life is the ISS support truss. STS-119 delivered and installed S6 truss on the ISS. The 14,088kg payload included solar panels, batteries, and truss superstructure, supplying last 25% of station's power, or 30kW. Say, double that to strap server-grade hardware and cooling on it. That's 1000*30/(2*14088) = 1.1kW of compute per ton to orbit. A 500kg 1kW server is overkilling it, but we are being conservative here.
In my past post I've calculated that fossil fuel electricity on Earth makes 296g CO2 per 1 kilowatthour (using gas turbine at 60% efficiency burning 891kJ/mol methane into 1 mol CO2: 1kJ/s * 3600s / 0.6 eff / (891kJ/mol) * 44g/mol = 296g, as is the case where I live).
The CO2 payback time for a ton of duct taped gamer PC is 1000kg * 26.5kg CO2/kg / ( 24kW * 0.296kg/kW/hour) / (24*365) = 0.43 years. The CO2 payback time for a steel truss monstrosity is `1000kg * 26.5kg/kg / (1.1kW * 0.296kg/kW/hour) / (24*365) = 9.3 years.
Hey, I was pretty close!
A solar-powered computer in space could recoup the CO2 cost of its launch fuel over its lifecycle (say 10 years?) when compared to coal-fueled electricity on the ground. After that it's free. Of course, you'd benefit more by filling up every available spot on the ground with solar arrays first! But you will eventually run out, or you might not want to do that.
If you have a megawatt solar array, you can also afford a megawatt cooling array. The size is comparable.
Closing a traffic lane on the Story Bridge for a temporary cyclist and pedestrian lane has been ruled out
Of course.
Yeah, with a Lagrange keyhole orbit past the Moon (which is what OP is asking about, not just plain escape velocity), you could park an Asteroid Belt asteroid in an orbit around the Earth. But it will be a high orbit. Not sure how low you could get it, I'm hoping a circular geostationary orbit is possible? But more likely something in the 300,000km range.
Low orbit is out of the question. Maaaybe you could park the asteroid in a highly elliptical orbit where the perigee is inside the atmosphere. The drag will circularize it if the asteroid is small enough. But not so small or weak that it burns up or breaks up before that happens. And not so big that drag takes too long and the orbit wobble makes it hit the surface. In a low Earth orbit you now only have 8km/s delta-v to deal with.
But to get the asteroid to gently touch the surface the way OP describes it, like some sort of skyhook? Is impossible short of a planet X or a rogue black hole passing even closer to the Earth than the Moon at the right moment. And whatever remains afterwards would be hard to call a surface: https://www.youtube.com/watch?v=kRlhlCWplqk
they build a new path
Hahahaha!
But seriously. They took a streetcar lane, which has been torn out and repurposed for a car lane, but is so narrow and uncomfortable to use that in modern day few cars ever use it. I took a note to count the cars last time I rode over the bridge - the middle lanes were bumper-to-bumper, but only two vehicles used the outer streetcar lane. It's open and accessible, the drivers just choose to avoid it. Even the current pedestrian/bike path in the former streetcar lane on the other side is too narrow to use, which is why adding more pedestrian space is necessary.
The 4 car lanes on the top level are the ones that repurposed the original pedestrian path, as well as replacing two additional railway tracks.
https://en.wikipedia.org/wiki/Queensboro_Bridge#Levels
What about the "Protocol on Mines, Booby-Traps and Other Devices" that somebody linked above? Not sure if it's the same as the "1996 Geneva Amendments" you mention, but both Ukraine and Russia are listed as signatories, and the language does seem to me to cover this exact situation:
Article 7
\ Prohibitions on the Use of booby-traps and other devices
- Without prejudice to the rules of international applicable in armed conflict relating to treachery and perfidy, it is prohibited in all circumstances to use booby-traps and other devices which are any way attached to or associated with:
\ (a) internationally recognized protective emblems, signs or signals;
\ ...
\ (d) medical facilities, medical equipment, medical supplies or medical transportation;
It says "medical supplies", without reference to humanitarian aid, and clearly stressing in "any way associated with". A "red cross" is also a recognized emblem. I can appreciate how "humanitarian aid" can be narrowly defined as medical supplies under direct control and chain-of-custody of the Red Cross Organization and doesn't apply to random medkits. But I can't see how this language above would not apply.
Or is it the case that this would be a crime, committed during war, but not a war crime? How does that work? Does it have to be a violation of a specific Geneva Convention(R) version to count as a war crime, and not just any UN war-related convention?
Only because it's English and the model is already trained on a large corpus of English text, so it has some idea of what a "table row" is for example. It could learn the concept from reading assembly code from scratch, it would just take longer. Hell, even Lego bricks can be trained on! https://avalovelace1.github.io/LegoGPT/
Our system tokenizes a LEGO design into a sequence of text tokens, ordered in a raster-scan manner from bottom to top. ... At inference time, LegoGPT generates LEGO designs incrementally by predicting one brick at a time given a text prompt.
Racing is fundamentally incompatible with safety. I'd like to see racing replaced with something like cooperative touring, where you compete to commute the most people the greatest distance along the most interesting routes with the least number of injuries and impact on the environment and surrounding communities.
Language is language. To an LLM, English is as good as Java is as good as machine code to train on. I like to imagine if we suddenly uncovered a library of books left over from ancient aliens, we could train an LLM on it (as long as the symbols themselves are legible), and it would generate stories in the alien language that would sound correct to the aliens, even though the alien world and alien life are completely unknown and incomprehensible to us.
was executedwas allegedly executed
Modern journalism sucks. Can't use affirmative voice for anything. Everything is "alleged" this and "sources say" that. Even with a concluded court case that has found proof of guilt beyond a reasonable doubt - the fairest way that we as a humanity have settled on for determining the truth or falsehood of questions like this - they still won't say the words.
quantum computing is revolutionary because it allows instant transmission of information across unlimited space
False and common misconception! In quantum mechanics there is even a theorem called the no-communication theorem that mathematically proves that no information can ever be transmitted by quantum entanglement. Sorry!
Good find!
Height: 45cm
Muwahahaha! Finally a table for my cat!
No way the table would be structurally strong enough, unless the flat part is made of steel painted to look like wood, therefore fake and imaginary.
Gravity—the curvature of space-time—can’t stop changes in the curvature of spacetime from propagating outward.
This is false. If it were true, you could build a device to communicate from inside a black hole event horizon. By waving around a heavy ball you would create gravitational waves that a sensitive enough LIGO outside the black hole could detect. But this is impossible. You would create gravitational waves, yes, but they would fall towards the center singularity same as you, and will never penetrate and escape the event horizon.
NYC is using "Leading Pedestrian Interval" on most intersections. This feature has been installed about 10 years ago. When the cross traffic light has turned red and your (the car driver's) traffic light is about to turn green, the pedestrian traffic light in the same direction turns green first. Your traffic light turns green a few seconds later, and the pedestrian light stays green. 15 seconds later, pedestrian light starts flashing red, and 30 seconds later both lights turn red at same time.
This few second advanced-pedestrian-green protects pedestrians from collisions with cars by allowing the squishy road users to saturate the crosswalk before the cars trying to make a right/left turn get a go. Cars making a turn have to wait. When both lights used to change green at same time, the drivers making a turn had too much temptation to just gun it across an intersection before the pedestrians reached the middle of it. NYC has very many intersections and very many pedestrians. This caused many collisions and injuries.
A 2019 city council law ammended the Administrative Code section 19-195 to clarify that bicyclists should use the advanced pedestrian green as well. This makes sense because bicyclists ride on the side of the road (in the right turn danger zone) and are in the squishy human category. NYPD hates bicyclists and ignores the law, pretending to "forget" it exists every time they write a citation violating it.
This server itself is already dedicated to all things gregtech! :D Don't think it makes sense to be creating new communities when there are only 2 posts on the server in past 6 months and one of them is mine. Let's wait until there are like 10 gregtech posts here then we'll see! ;)
Use wireshark and listen on your ethernet interface. When you use tailscale, are the packets coming in/out from the tailscale server IP or the VPN ip? Check through the ip route routing table and figure out which pathway a packet will take in each use case. Might need to add a route exception specifically for the tailscale server IP to go out on the ethernet device.
In terms of kWh per kWh, by how much does greenhouse CO2 from running an air-conditioner heat up the rest of the Earth?