TauZero

joined 2 years ago
[–] TauZero@mander.xyz 2 points 4 days ago (1 children)

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!

[–] TauZero@mander.xyz 1 points 4 days ago (3 children)

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.

[–] TauZero@mander.xyz 1 points 4 days ago

If you have a megawatt solar array, you can also afford a megawatt cooling array. The size is comparable.

[–] TauZero@mander.xyz 2 points 4 days ago

Closing a traffic lane on the Story Bridge for a temporary cyclist and pedestrian lane has been ruled out

Of course.

[–] TauZero@mander.xyz 3 points 4 days ago

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

[–] TauZero@mander.xyz 4 points 4 days ago* (last edited 4 days ago) (1 children)

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

[–] TauZero@mander.xyz 1 points 6 days ago (1 children)

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

  1. 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?

[–] TauZero@mander.xyz 3 points 1 week ago

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.

[–] TauZero@mander.xyz 2 points 1 week ago

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.

[–] TauZero@mander.xyz 27 points 1 week ago (1 children)

~~was executed~~ was 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.

[–] TauZero@mander.xyz 0 points 1 week ago

12:30 AM GMT 🤡

[–] TauZero@mander.xyz 3 points 1 week ago

Good find!

Height: 45cm

Muwahahaha! Finally a table for my cat!

 

All I wanted was to play the Factorio expansion, but Lemmy told me "Why play an imitation factory game when you could experience the original that inspired them all - gregtech?" So I did. Five months later, here we are.

TerraFirmaGreg is an unholy fusion of TerraFirmaCraft and GregTechCEu Modern. I just picked whatever modpack was popular at the time and ran on modern minecraft (1.20.1), and got pretty lucky with my pick. This gregtech version is actively developed, and while it is not the hardest greg out there, in combination with TerraFirma it becomes maybe 2nd hardest overall. It takes like 200 hours just to get an electric furnace! Congrats to the devs for making it all work.

There are some bugs here and there, some that even seemed like they would block progression, but turns out there is an in-game workaround for every one of those, and the entire full intended progression is currently completable in survival! I've used some creative-mode workarounds for non-game-breaking bugs, like spawning in Firmalife compost tumblers (and waterwheels to power them) and greenhouse sprinklers, which exist and work but are missing a recipe, and tier 2 space rockets which are also missing a recipe. I heard some more bugs have been fixed by the devs since, but I was too afraid to update an already working installation.

The game balance is here and there, but again everything is completable in the end. Like any proper factory game, the lack of any particular resource at any point in progression is more a problem of insufficient production for that resource than of game balance per se :D The exponential growth power curve smooths out all kinks after a couple doubling steps anyway.

I can even kinda agree with keeping fire clay so rare, a controversial topic in itself that the devs have resisted to budge on. You have to travel over 10k blocks to the equator to find it. While it is annoying to have to spend an hour in a boat each way, in retrospect I appreciate having being able to experience the full range of TerraFirma biomes. I might not even have known they existed if I did not have this reason to go on this journey, or have adventures like being suddenly chased by an alligator. It's also fun to build and use multiblock sailing ships, for which sailing to the equator is their primary purpose.

For some ideas going forward, I'd like to see the spaceflight part of the modpack completed further. The rocket recipes fixed up, some tier 2 spacesuits, and the planets populated with lategame ore. Alpha Centauri (once it actually works) would be a great place to stick ~~unobtainium~~ naquadah, as I had to stripmine my entire overworld in search for it to make trinium for fusion coils. I heard the devs even raised naquadah spawns since then, but outer space would be a great alternative place for it.

I would also like to mention the youtubers Dragonium and Flurben who are doing a complete playthrough series of the modpack as a team. My experience with the modpack has been made ever more satisfying by being able to see other players go through the same challenges I did as I was doing it, and to compare their solutions. The Dragonium terrafirmagreg tips for every tech age sequence is particularly high production value and useful. Thx!

I wanted to post this report somewhere, and this latestagecapitalism sublemmy is the only existing community on this server dedicated to all things gregtech (and also someone named greg unrelated to gregtech, but mainly gregtech :D), so I'll post here. To fit the theme, here's a map marking all the resources I have mined out that were necessary for progression. Devastating all landscape within a 3000 block radius to further factory needs is latestagecapitalism, right?

 

Bicycle/pedestrian path on the Queensboro Bridge in New York City. The two trenches are worn entirely by bicycle tire traffic. These are not car tracks as the width slightly varies later. The city has done zero effort to clean the bridge paths after the snow and almost zero effort to clean protected street bicycle paths. The intended use for this path is for pedestrians to be on the right half (you can see the middle dividing white line if you look for it), and for bicyclists to use the left two quarters. You can notice the yellow line intended to divide the two directions of bicycle traffic, with about 2ft per direction. The actual spacing resulting from natural use is on display and apparently way different.

 

Needed a replacement 700C front wheel for my commuter bike after the old aluminum rim exploded like a looney tunes cannon. It's hard enough to find the right size when there are 3 competing tire/rim sizing systems currently in use, it doesn't help when the people selling the wheels have no idea what the numbers mean either! All of these examples are from separate storefronts at the big online store. Ended up buying the wheel identical to mine from my local bicycle shop at the same price as online and with no shipping fee or delivery time.

The 3 systems in use are the American customary inch fraction notation like 26x1+3⁄4 (which is NOT interchangeable with American customary inch decimal notation like 26x1.75), the French metric notation like 650x45C, and the ISO 5775 metric notation like 47-571. I found the wikipedia conversion tables and Sheldon Brown's tire size chart invaluable.

 

To better understand how neural networks function, researchers trained a toy 512-node neural network on a text dataset and then tried to identify features within the network that are semantically meaningful. The key observation is that while individual neurons are difficult to attribute specific functionality to, you can find groups of neurons that collectively do seem to fire in response to human-legible features and concepts. By some metric, the 4096-feature decomposition of the 512-node toy model explains 79% of the information within it. The researchers used an AI nicknamed Claude to automatically annotate all the features by guessing how a human would describe them, like for example feature #3647 "Abstract adjectives/verbs in credit/debt legal text", or the "sus" feature #3545. Browse through the visualization and see for yourself!

The researchers called the ability of neural networks to encode more information than they have neurons for as "superposition", and single neurons being responsible for multiple, sometimes seemingly unrelated, concepts as being "polysemantic".

Full paper: https://transformer-circuits.pub/2023/monosemantic-features/index.html
also discussed at: https://www.astralcodexten.com/p/god-help-us-lets-try-to-understand
and hackernews: https://news.ycombinator.com/item?id=38438261

 

OC just for you! ♥️

 

The recent post made me fear that a lot of you are taking this "monkey looks at double-slits" meme, which was only ever supposed to be a funny monkey meme, actually seriously. Honorable mention goes to @kromem@lemmy.world, whose 12 posts on the topic, insisting that the quantum eraser experiment (but not the delayed-choice quantum eraser!) proves that the double slit is somehow bizarre, forced me to make my own meme. This meme explains the (non-delayed choice) quantum eraser paper from arXiv:quant-ph/0106078 and the figures are numbered to reference the paper.

First of all, looking at the photons, you the conscious intelligent monkey, MAKES NO DIFFERENCE. You can't actually "see" the photons going through a slit the way you could see say a bowling ball. The only way to detect a photon is to absorb or reflect it, and if the photon is getting absorbed by your eye that means it's not going through the slit or hitting the screen. The interference pattern stays visible on the screen WHETHER OR NOT YOU LOOK AT IT.

They've lied to you when they said the pattern changes when you "look" at which slit it the photon goes through. What the physicists actually do to measure the "which path" information is they put these circular polarizer filters in front of the slits, one clockwise one counterclockwise. Then the pattern disappears and you get this one single blob of density (Not even double! Figure 3). This is because light polarized in opposite directions cannot interfere with itself - wikipedia calls this the "Fresnel–Arago laws". In principle you could have put a polarization detector in place of the screen and record which way the light hitting it is polarized, which would tell you which slit the photon must have went through. The physicists DON'T EVEN BOTHER DOING IT. The fact alone that the light is polarized when it hits the screen is sufficient to destroy the interference pattern.

Well, NO SHIT. You put these giant 3D glasses in front of the slits and you still expect to see interference? This is very much a "mechanical interaction", not some "non-obtrusive conscious observation". Everything that destroys coherence will ruin your quantum experiment! Mystery solved!

So what about the quantum eraser, @kromem will ask? Popular science has created this myth that you can look at the screen and you can make the interference pattern literally shimmer in and out of existence by just flipping a switch, connected to second detector positioned elsewhere, turning it off and on. An action at a distant place (the detector POL1 observing "twinned" entangled photons created by this fancy nonlinear barium crystal before the slits, Figure 1) changes whether light over here behaves as a particle or a wave, right in front of your eyes. Spooky action at a distance, right?

THIS FUCKING DOESN'T HAPPEN. The monkey will see the single blob from Figure 3 and only single blob, no matter whether it turns the second detector on or off! The interference pattern will NEVER shimmer back into existence. The light never switches between behaving like a wave and behaving like a particle. It always behaves the same way, all the time, everywhere in the universe - like fucking light!

So what do the physicists actually fucking mean when they say the interference pattern is "restored"? If you observe the photons hitting the screen one at a time and you correlate them with simultaneous detections at detector POL1, you can mark those events as either "yes coincidence" category A or "no coincidence" category B. If you look at just all the category A events (Figure 4) you will see an interference pattern, and just category B you will see another (Figure 5). You cannot see these patterns by eye on the screen! You have to use a computer to record the events individually and separate them, you will only ever see a single blob by eye. The two interference patterns are subsets of that blob. They were always part of it, their hills and valleys mesh together into a single continuum. NO ONE EVER FUCKING EXPLAINED THIS.

The detector POL1 has a linear polarizer filter in front of it, so straight out the gate it will not see 50% of the twinned photons at all, because they will get stuck in the filter. Your category A can never match more than 50% of events. It gets worse, since the non-linear crystal in reality has very low efficiency and most photons going through are not twinned, so you cannot measure category B directly. In the experiment they do it by rotating the filter 90°, which changes the correlation to category B. In the meme I show them as if the crystal was 100% efficient.

The delayed-choice quantum eraser works similarly - you only ever see a single blob and can never see the interference pattern shimmer in and out of existence. You need the correlation data from the second detector to split the blob into two intermeshed interference patterns using a computer. The Sabine video was the first one I've ever seen that explains this correctly. Every other popular science video up to that point has lied to me!

Whatever you do, DO NOT watch the DR. QUANTUM video with an open mind! (Not even going to link to it, @manual3204 linked it in the other thread.) It's from a documentary produced by a literal UFO cult to promote their quantum woo woo, only masquerading as a quirky science video. It came out in the early days of youtube, when its production and animation quality were unusually high for its time, so it immediately became youtube's go-to video for double slit experiment. Copies of it remain highly ranked there even to present day. It's total baloney!

 

All the McD*nalds in my area have been upgraded with order kiosks. Regardless of all the controversy around self-checkout, and minimum wage, and automation taking our jobs, I personally love them. I can take my sweet time composing my order, I can see the full selection (such as it is), I can see pictures and prices clearly without having to strain my eyes to read 12pt font on the tableau, and I don't have to shout at the cashier to be understood or struggle to hear back. I really believe this is the right way forward.

My only complaint so far has been that the order kiosks only accept card. There is actually a way to pay by cash that the machine never lets you know about - you have to press "cancel" on the keypad when it asks to insert card, and then the screen gives you an order number to give to the human cashier (each store still has one register open) so you can pay in cash. So I still have to wait on line, but at least my order selection is locked in, I can have exact change ready, and there isn't usually a line anyway anymore.

I know all yall Europeans are proud about your nearly total transition to cashless economy or whatever, and you like to boast how not a single euro banknote has graced the inside of your wallet in months. However I personally like cash, and I genuinely believe that a cash payment system is a necessary element of a liberal democracy and secure society. So at least understand my pleasant surprise when I saw these reverse-ATM cashboxes at this restaurant. They work and were being actively used too! (It spat out my dollar coins though, those bastards!) I hope they find their way into more places.

 

It is said that ACs are counterproductive in fight against global warming, in that while they may make the local environment temporarily livable, the greenhouse gases produced while making the electricity needed to operate them heat up the rest of the Earth by much more than the relief from the AC itself. By how much exactly is that? Note that here I am interested in the global impact of greenhouse gases specifically, not in the local heat island effect (given how ACs do not destroy heat but only move it from inside to outside, and add extra heat from running the compressor itself). Let's also assume all electricity comes from fossil fuels (ACs might become a viable solution if 100% of AC electricity came from renewable solar, which is actually a reasonable goal to strive for given how both AC and solar are most active during the day, but at the moment most of electricity delivered to me specifically, for example, comes from natural gas.)

Here's my estimate. Let me know if it is reasonable! Methane has energy density of 891 kJ/mol, burnt into CO2 at 1 mol : 1 mol. Gas turbines have efficiency up to 60%. The radiative forcing of CO2 can be calculated as: ln(new ppm/old ppm)/ln(2)*3.7 W/m**2. For example the 131 ppm increase in CO2 since 1750 up to 411 ppm has a radiative forcing of 2.05 W/m**2 (is that across the entire Earth's surface? or only its crosssection?), and CO2 has persistence in atmosphere for at least 1000 years. The atmosphere composition is 78% nitrogen 21% oxygen 0.9% argon so its molar mass is:

.78 * 28 g/mol + .21*32 g/mol + .009*18 g/mol = 28.7 g/mol 

And total atmospheric mass:

4*3.14*(6.37e6 m)**2 * ~10000 kg/m**2 * 1000 g/kg / (28.7 g/mol) = 1.78e20 mol

Suppose 8 billion people each run 1kW AC for 1 year, with electricity from natural gas. (That's similar to our total current global energy consumption of 20TW, though of course we use power for things other than just AC or electricity, but also most energy comes from coal and gasoline not just gas, and 80% comes from fossil fuels not renewables.)

8e9 people * 1000 W/person * 60*60*24*365 s / (891e3 J/mol * 0.6) = 472e12 mol

That's 472 teramols of CO2 (20.8 gigatons) added to the atmosphere each year, or 472e12 / 1.78e20 * 1e6 = 2.65 ppm (parts per million). It is believable that having done so for a hundred years we have raised CO2 concentration from pre-industrial levels up to 411 ppm. The radiative forcing is:

ln((411 ppm + 2.65 ppm)/(411 ppm)) / ln(2) * 3.7 W/m**2 = 0.0343 W/m**2

Or for the whole earth:

4*3.14*(6.37e6 m)**2 * 0.0343 W/m**2 = 17.5 TW

What is my individual contribution for 1 hour?

17.5e12 W / 8e9 / (24*365) = 0.25 W

That is, if I run my 1kW air conditioner for 1 hour, the entire Earth will be solar heated by an extra 0.25 W for the next 1000 years. That doesn't sound like much, but it adds up over time: I spent one kilowatt-hour in one hour on cooling, but the rest of the Earth will be heated by an extra 0.25 W * 24*365 hours = 2.2 kilowatt-hours in the next year, and again every year thereafter. Multiply that by 8 billion people or a hundred years and it adds up a lot, even considering the heat is distributed across entire planet surface not just areas where people live.

So my answer is 1 kWh of cooling = 2.2 kWh of heating per year for the next 1000 years. By same calculation in terms of mass, 1 kg of CO2 = 7.4 kWh of heating for every year thereafter. Is this accurate?

 

Everyone is armed all the time and that's normal, but to draw a weapon is an overt hostile act. A standoff therefore is a game of chicken because both want to kill each other and you want to draw first to have the highest chance of surviving, but even a bandit will hesitate to add a felony murder charge to their rap sheet. The whole town serves as witness when there is a pair of eyes behind every shuttered window. The hero always draws second, both demonstrating his superior skill and speed by defeating the opponent even at a disadvantage, and getting away with murder scot-free.

 

cross-posted from: https://lemmy.world/post/2144441

Huge if this is true. Claim is: They have attained superconductivity at room temperature and ambient pressure. Also superconductivity holds till 127 C.

There is a discussion on Hacker News

89
submitted 2 years ago* (last edited 2 years ago) by TauZero@mander.xyz to c/memes@lemmy.ml
 

Image description - Cuphead Rage Flower meme
Me seeing cheap and expensive nuts mixed together for sale on the shelf
Me buying expensive nuts and mixing in cheap nuts myself

[Edited for CAPSLOCK]

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