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The 500k-ton typo: Why data center copper math doesn't add up

111 points16 hoursinvestinglive.com
Fiveplus14 hours ago

The funniest part is beyond the typo, the complete lack of physical intuition from the analysts who circulated this. 500,000 tons is roughly the weight of 1.5 Empire State buildings. If your rack busbars weigh more than the structural steel of the facility housing them, you have a geotechnical engineering crisis on your hands. It is wild that we reached a point where financial modeling is so decoupled from physical reality that nobody paused to ask if the floor would collapse.

lm2846911 hours ago

When I asked gemini it got it right away and as a source it provided a link to your comment... what a time to be alive, I hope you got the Empire State buildings calculations right because you're now part of the Truth ™

https://imgur.com/a/NaTfvtS

kibwen10 hours ago

The irony is that I feel like everyone here is just copping off of WolframAlpha, which for the past 15 years has featured the ability to display references of similar magnitude for any query you give. And in fact, typing in "500,000 tons" into WolframAlpha tells you specifically that this is 1.4x the mass of the Empire State Building (and also 0.8x to 1.4x the mass of an Ultra Large Crude Carrier oil supertanker, and also 0.11x the mass converted to energy by the sun in one second).

https://www.wolframalpha.com/input?i=500%2C000+tons

Aurornis14 hours ago

The world of financial analysis and modeling is broad. It’s common to give these tasks to juniors and expect them to grind through it when the output doesn’t really matter.

In this case the output wasn’t actually used for financial modeling. If it had been, it would have been caught immediately when someone put it into a table where they calculated the price or the supply constraints or anything else.

matthewaveryusa13 hours ago

Just to make it even more real: During covid I added a sub-panel and the wire (more like the sausage given the girth) between the sub-panel and main panel was aluminum because of cost. You just need to be a tad careful at the connection points with copper -- nothing a caring literate person can't handle

SoftTalker11 hours ago

The incoming drop for a service panel is almost always aluminum (at least the residential stuff I've seen). It's cheaper and lighter than copper while still being ductile enough to work with. Just use the proper antioxidation paste at the connection point.

quickthrowman11 hours ago

Did you use antioxidant paste on all of the aluminum terminations? If you didn’t, please pay an electrician to come fix it. If you did apply the paste, you are in the 0.01% of non-idiot non-electrician homeowners and can skip my rant about homeowners doing electrical work in the next paragraph. I sell electrical work and have seen some incredibly poor work done by homeowners.

Do not install aluminum wire if you are a homeowner unless you already know enough to use antioxidant paste and also to use a torque screwdriver or torque wrench for terminations and know where to find the torque values for the wiring devices you are using. If you don’t apply the paste, the surface of the aluminum will oxidize and could catch fire due to increased resistance.

I suggest not even touching copper as a homeowner, but it’s your choice and your house.

mschulkind4 hours ago

Kind of overstating things here. Noalox has not been required for modern materials made in like the last 30 years.

viggity11 hours ago

Kinda like when someone said that instead of running for mayor, Bloomberg could have given everyone in the country $1M. A guest said it on NBC and Bryan Williams, nor the pundit had any intuition that it seemed grossly wrong. https://www.politifact.com/factchecks/2020/mar/06/msnbc/bad-...

lazide11 hours ago

The system incentivizes ‘sounds good’ over ‘is correct’.

If news agencies needed to pay out fines for false info, you better believe they’d be checking more.

carlesonielfa12 hours ago

My first thought was, this is the kind of thing that an LLM writes and nobody checks. But then I realized, any decent LLM would have probably caught that inconsistency

observationist11 hours ago

Yeah, the good ones will use tools and give you a nice markdown table. Any claims like this anymore, I trust AI to go through it and give the numbers a reality check. With all the claims made about datacenter resources, power, and water usage, it's darkly funny how bad people are at understanding these things.

The math they do with their assumptions is usually pretty good, and you can tell when they put in the effort, but wow, the models and assumptions are all over the place.

schainks11 hours ago

2008 would like a word.

cyanydeez7 hours ago

Do we think the people pushing new age LLM saviors are more or less stupid?

franktankbank14 hours ago

I wouldn't be surprised if that part was not really reviewed by an expert. They have the unit mass correct but maybe an editor is like ok but what does this look like for a gw project? It doesn't take more than 3rd grade math and a pocket calculator to do it correctly but journalist hasn't had to fumble that ball before. An expert knows its all too easy for any person to make that mistake and would second guess their own work.

crote14 hours ago

With regards to the copper market: it keeps surprising me that some people seem to assume copper is a hard requirement for conducting electricity.

In reality copper is just convenient. We use it because it's easy to work with, a great conductor, and (until recently) quite affordable. But for most applications there's no reason we couldn't use something else!

For example, a 1.5mm2 copper conductor is 0.0134kg/m, which at current prices is $0.17 / meter. A 2.4mm2 aluminum conductor has the same resistance, weighs 0.0065kg/m, which at current prices is $0.0195 / meter!

Sure, aluminum is a pain to work with, but with a price premium like that there's a massive incentive to find a way to make it work.

Copper can't get too expensive simply due to power demands because people will just switch to aluminum. The power grid itself had been using it for decades, after all - some internal datacenter busbars should be doable as well.

dzink14 hours ago

You just have to not mix and match. If you mix them the two need special bonding at every single connector or they can cause arching and fires.

amluto11 hours ago

If by “special” you mean ordinary low-cost lugs, then sure.

Check it out:

https://lugsdirect.com/WhyAluminumOverCopperFAQ.htm

And you can browse that site for lugs, and they’re mostly rated for aluminum and copper. Copper-only lugs are actually rather unusual.

Sure, you can’t stick copper and aluminum wires into a wire nut, and finding terminations for smaller-gauge aluminum wire can be hard. But for larger wire, it’s really no problem.

quickthrowman11 hours ago

Most wiring device terminations and lugs are Al/Cu rated. You’re supposed to use specific fittings for splicing together aluminum and copper wire (specific WAGO lever nuts are UL listed for this purpose along with some others), I assume that’s what you meant.

nerdralph11 hours ago

Most residential 200A electrical panels use tin plated aluminum busbars. https://www.eaton.com/cr/en-us/catalog/power-connections/bus...

quickthrowman6 hours ago

Most commercial panelboards and transformers also use aluminum buss.

pfdietz11 hours ago

One good reason for moving from copper to aluminum is that copper contaminates recycled steel, but aluminum doesn't. Fortunately these days it's profitable to carefully extract most of the copper wire and such from scrap steel before it's melted down.

y-curious14 hours ago

I am not an electricity/wiring guy so maybe you can help me understand. I thought aluminum is dangerous to wire with because it is a fire hazard (I bought a home this year and this was a prominent warning in my reading). Is that because it needs to be done very carefully? I imagine most data centers would not mess with a fire risk on such a scale.

crote14 hours ago

That's the "a pain to work with" part.

Residential aluminum is a Really Bad Idea because DIY Dave will inevitably do something wrong - which then leads to a fire hazard. Copper is a lot more forgiving.

But a large scale datacenter, solar farm, or battery storage installation? Those will be installed and maintained by trained electricians, which means they actually know what a "torque wrench" is, and how to deal with scary words like "corrosion" and "oxidation".

Like I said: it's what's used for most of the power grid. With the right training it really isn't a big deal.

jabl13 hours ago

Aluminum got a bad rep due to a lot of poor installations made in the 1960 and 70'ies. Subsequently new alloys (AA-8000 series) for wiring, new installation and termination procedures etc. have been developed, and AFAIU the situation today is much better. It's still trickier than copper wiring, so probably not a good option for DIY, but for some industrial installation with competent personnel and where the savings can be substantial it could certainly be an attractive option.

https://en.wikipedia.org/wiki/Aluminum_building_wiring

scherlock14 hours ago

Aluminum oxide has high resistance and if you mix aluminum wiring with copper outlets, etc the impedance mismatched is what causes fires. You need to either have special copper pigtails installed or use fixtures that are rated for aluminum wiring.

For commercial installs, it shouldn't be a problem as long as it's planned for.

auxym14 hours ago

It's because aluminium has a higher coefficient of thermal expansion. It expands and shrinks more as it heats, and as those cycles add up it tends to loosen electrical connections. Loose connections have higher resistance, heat up and can cause fires.

That said, there is no reason we can't design better connectors that can withstand the expansion and shrinkage cycles, like spring loaded or spring cage connectors.

quickthrowman6 hours ago

Wiring devices have almost all been universally rated for Al/Cu conductors for the last 50 years, what you’re talking about only lasted a handful of years in the early 1970s.

Go look at the terminals on any light switch or receptacle at Home Depot, they’re all Al/Cu rated.

_heimdall14 hours ago

Unless I'm mistaken, the risk with aluminum is that it can expand and contract if it gets too hot. Aluminum sized properly with the correct connectors torqued to spec would be fine, aluminum wires in a residence with a DIYer working on it can be riskier and is why inspectors will always note it.

u808014 hours ago

Aluminum wires became brittle over time(tens of years), fluid which requires some maintenance for screw terminals and inducts galvanic corrosion when coupled with copper without special care. If wiring was properly done and maintained, it is okayish.

MSFT_Edging14 hours ago

Old aluminum wiring in your walls with cloth insulators, designed for a time where electricity consumption was a small fraction of today's electrified usage is dangerous because you're overloading an old, unprepared system.

Aluminum bus bars(solid, often exposed) would be designed for the required power levels and installation criteria.

Aurornis14 hours ago

Aluminum home wiring was from the 60s and 70s. It’s not the same as cloth covered knob and tube from earlier years. It has its own problems, but I’d take a house with knob and tube over a house with aluminum wiring.

margalabargala12 hours ago

Household electrical usage has decreased, not increased, since that time. Your scaling is backwards.

Old aluminum wires in your walls were designed for a time when you lit your home with 100 watt incandescent lamps rather than 12 watt LEDs.

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quesera12 hours ago
knollimar13 hours ago

Old aluminum is dangerous. Modern aa-8000 series aluminum is fine. Bigger pipes though.

quickthrowman11 hours ago

If you apply antioxidant paste, torque the terminations to the correct value, and use wiring devices rated for Cu and Al conductors, there are zero problems.

Most homeowners know none of the requirements of aluminum wire installation so I don’t recommend using it, oxidation is bad and can cause fires. Just pay for copper NM cable, it’s dirt cheap anyways.

FWIW I sell and run electrical work for a living. I assume crote and amluto work in the electrical industry, since they’re the only other posters in this discussion who know what they’re talking about.

Analemma_14 hours ago

It’s a fire hazard in residential houses where people frequently do their own wiring, because it needs more expertise to wire correctly. Copper wiring is a lot more forgiving to being hooked up by amateurs.

The biggest reason is that aluminum oxidizes, and unlike copper, the oxide layer has high resistivity. In theory that shouldn’t be an issue in datacenters hiring expert technicians.

pixl9713 hours ago

Yea, in a data center setup the cost difference can justify the things like soldiering connections rather than mechanical connectors with a higher resistance.

zahlman12 hours ago

> In the Earth's crust, aluminium is the most abundant metallic element (8.23% by mass[68]) and the third most abundant of all elements (after oxygen and silicon).

TIL. I thought it would be relatively expensive due to the difficulty of extracting it.

(Iron is much cheaper than I thought, too.)

crote12 hours ago

It used to be extremely expensive!

The Washington Monument has an aluminum cap, which at the time was as expensive as silver. Two years later the Hall-Héroult process was invented, and as a result the price plummeted.

newyankee11 hours ago

Aluminium essentially reflects electricity prices and increasingly recycled

candiddevmike14 hours ago

AFAIK Aluminum wires will become a heat liability, especially at higher amps

crote14 hours ago

That's why my calculation example used a 1.5mm2 copper wire but a 2.4mm2 aluminum one.

Aluminum has a higher resistance, which means the same diameter will get hotter than copper. Make the cable thicker and its resistance drops, which means it gets less hot.

Want more amps at the same temperature? Ohm's law still applies: just use a thicker cable.

pfdietz11 hours ago

Aluminum has lower resistance per kg, or per $. This is why transmission lines use aluminum (around a steel core).

greggyb14 hours ago

Any wire---of any non superconducting material---will be hotter at higher current flows. You size the wire to the application.

mmulqueen13 hours ago

It depends on design, environment and maintenance. If it's well protected against oxidation and it's static, it's not really a problem. Heat issues are often at the joints, which are most vulnerable, but can be coated and encapsulated to mitigate. For some uses, aluminium is superior to copper all things considered. Obviously the diameter of the wire/cable depends on which conductor you use, AC/DC, current and service temp - for some applications, that may favour one material over the other.

MSFT_Edging14 hours ago

If the two wires are the same gauge, yes. If you size up the aluminum, at the same resistance/current would mean the same amount of power over the length of the conductor and same heat.

lillecarl14 hours ago

Thicker cables or higher voltage(lower current) is the answer which is why it's used in power distribution networks where they can control the voltage by planning what to transform to.

quickthrowman6 hours ago

You are incorrect.

Wire can be used for up to whatever ampacity is listed for that size wire and temperature rating in Table 310.16 (Conductor Ampacity) Copper and aluminum have separate ampacity tables because you need to use larger aluminum conductors.

Example:

#250MCM THHN copper can handle 255A in a commercial setting (75C column)

#250MCM THHN aluminum can handle 205A in a commercial setting (75C column).

NEC ampacity table: https://media.distributordatasolutions.com/ThomasAndBetts/v2...

nirui13 hours ago

> In reality copper is just convenient. We use it because it's easy to work with, a great conductor, and (until recently) quite affordable

It's convenient, it's easy to work with, great conductivity, and cheap enough all at the sametime... Dude, I think you just explained why cropper is used instead of anything else.

jandrese12 hours ago

> and cheap enough

Not anymore. :(

quickthrowman5 hours ago

Wire has barely gone up in price, I was paying $175 for 1000’ of #12 THHN a year ago and today it’s about $190 for 1000’ of #12 THHN.

It’d be nice to get 1000’ of 12-2 MC cable for $500 again, but those days are gone.

amluto11 hours ago

> Sure, aluminum is a pain to work with

Really? In larger sizes, an equivalent ampacity aluminum cable is generally lighter and more flexible than copper. The main downside is that it’s thicker.

(Common terminations for larger wire sizes are often dual-rated for aluminum and copper. The engineering details for how to design lugs that work well for aluminum and copper were worked out long ago.)

fedeb9514 hours ago

interesting, thanks!

kmbfjr14 hours ago

Aluminum conductors are dangerous unless the entire system is designed for it. It is not a case of switching to something cheaper.

Look at the electrical fires of the 1950’s and 1960’s as an example, and that was at household levels of current.

Aluminum is used, but everything accounts for the insane coefficient of linear expansion and other annoying properties.

greggyb14 hours ago

I would imagine most large-scale data center construction projects will include electrical engineers to design the electrical subsystem. A rack's floor footprint is a few square feet. You can put several million dollars of hardware into that rack. A data center will have at least a few racks. It's a very reasonable investment to bring someone in to do electrical design.

knollimar13 hours ago

This isn't true at all unless you narrowly dwfine "the entire system".

Each feeder can be aluminum if you put special goop on any copper connections. Breakers accept it just fine, etc.

You should avoid it for smaller wiring, though. There's special 8000 series aluminum if you're trying to be serious with Al feeders

amluto11 hours ago

The goop is generally considered to be unnecessary. What you need is a termination that is rated for aluminum wire, and these are very, very common as long as the wire in question is fairly large (8AWG or so and larger).

knollimar11 hours ago

I only put it in the comment since the commenters here seemed uninformed.

It's better to be safe and follow specs; it's more when you're doing some compound splice where it makes sense. I figure it'll make more people feel easy about it if there's a preventative measure

daeken15 hours ago

This sort of mistake is easy to make when you're mixing up your units; if they kept to one system of measure, it would've been trivial to catch, before or after release.

testplzignore15 hours ago

We need to standardize on using Earth circumferences as the unit of length. Or better, football fields! (the type of football of course being implied by the website's ccTLD)

Pinus15 hours ago

We _have_ standardized on Earth circumferences for length, only we divide by 40 million to make the numbers more sane, and got the measurement slightly wrong!

crote14 hours ago

We should just redefine it to make the speed of light a nice even 300.000 km/s - we are so close already!

SAI_Peregrinus13 hours ago

But it's already a nice round 10m/s in base 299,792,458.

jasomill10 hours ago

Why stop there when we could just as easily redefine it to be 1 (new base unit of length)/second or 1 meter/(new base unit of time)?

Ekaros12 hours ago

How hard would it be to fix this? Could we theoretically add or subtract enough material or make whole thing slightly more dense or less dense to compensate?

jasomill10 hours ago

Per Wikipedia, the discrepancy is approximately 74 km, so digging a ditch with an average depth of approximately 74/2π ≅ 12 km around the circumference of the Earth would theoretically fix the problem.

Feasibility and geological implications are left as exercises for the reader.

Regardless, I suspect a more cost-effective fix would be to redefine the meter to be a couple "legacy" millimeters longer.

eterm15 hours ago

If only there were some kind of international system of standard units.

blitzar15 hours ago

Olympic swimming pools for liquids, times around the the earth for length and number of double decker busses for height.

literalAardvark15 hours ago

You jest, but times around the Earth is the actual origin of the Meter. Kinda.

The history is quite interesting and well worth checking out.

I can't recommend a book on the subject, but I do heartily recommend "Longitude", which is about the challenges of inventing the first maritime chronometers for the purpose of accurately measuring longitude.

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EA14 hours ago
RobotToaster15 hours ago

For smaller lengths and radiation bananas are also acceptable.

lostlogin14 hours ago

A good physicist can calculate banana equivalent dose other head. Always ask for it when dealing with radiation.

jasomill10 hours ago

Don't forget packs of cigarettes as a more convenient unit for measuring volumes significantly smaller than Olympic-sized pools.

There is, of course, no more need to standardize on a specific brand or style of cigarette than on a specific depth of Olympic-sized pool.

brookst15 hours ago

Don’t forget cheetahs for velocity and elephants for weight.

blitzar10 hours ago

A horse as a measure of power and a crocodile bite as a measure of compression strength

dredmorbius8 hours ago

Or vice versa.

coldcode14 hours ago

I thought all measurements in data centers were in US football fields.

Nifty392912 hours ago

For the floor area or length/width it is, but if you want the height then that's in Empire State Buildings.

paulddraper12 hours ago

There are standard units, yes.

NoNotTheDuo13 hours ago

Amazingly ironic that in an article about a typo, there is a typo.

> "Tat sounds like the ultimate catalyst for the commodities market and copper has been hitting records."

"Tat" should be "That", imo.

NooneAtAll311 hours ago

you should've made a typo as well, as per tradition

sidewndr4613 hours ago

I interpreted the typo as a meta commentary on the state of journalism in the 21st century.

zekyl31413 hours ago

I saw this too, awesome to report on a typo when you yourself have a typo. What are the odds?

zenoprax13 hours ago
amtamt13 hours ago

but one weighs half a million ton ¯\_(ツ)_/¯

mrbonner13 hours ago

It’s interestingly related that Amazon is also buying a copper mine: https://www.wsj.com/finance/commodities-futures/amazon-is-bu...

flakeoil11 hours ago

They don't buy a mine they buy the output.

compressedgas15 hours ago

The error in the original article has been corrected.

https://developer.nvidia.com/blog/nvidia-800-v-hvdc-architec...

nine_k15 hours ago

> If the "half a million tons" figure were accurate, a single 1 GW data center would consume 1.7% of the world's annual copper supply. If we built 30 GW of capacity—a reasonable projection for the AI build-out—that sector alone would theoretically absorb almost half of all the copper mined on Earth.

Quickly doing such "back of an envelope" calculations, and calling out things that seem outlandish, could be a useful function of an AI assistant.

9dev15 hours ago

Using your brain is so vastly more energy efficient, we might just only need half of that 30 GW capacity if fewer people had these leftpad-style knee-jerk reactions.

blueg314 hours ago

A Gemini query uses about a kilojoule. The brain runs at 20 W (though the whole human costs 100 W). So, the human is less energy if you can get it done in under 50 seconds.

9dev14 hours ago

Where does that number come from? Does it factor in the energy required to build the servers used to train the model? Does it factor in… the training?

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pixl9713 hours ago
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lostlogin14 hours ago
lostlogin14 hours ago

If humans aren’t more efficient the energy is still used, as they remain alive. Maybe the AI will notice this?

wongarsu15 hours ago

Each person uses about 100W (2000kcal/24h=96W). Running all of humanity takes about 775GW.

Sure, using or not using your brain is a negligible energy difference, so if you aren't using it you really should, for energy efficiency's sake. But I don't think the claim that our brains are more energy efficient is obviously true on its own. The issue is more about induced demand from having all this external "thinking" capacity on your fingertips

program_whiz15 hours ago

Is there an AI system with functionality at or equal to a human brain that operates on less than 100W? Its currently the most efficient model we have. You compare all of humanity's energy expenditure, but to make the comparison, you need to consider the cost of replicating all that compute with AI (assuming we had an AGI at human level in all regards, or a set of AIs that when operated together could replace all human intelligence).

pixl9713 hours ago

>all human intelligence

So, this is rather complex because you can turn AI energy usage to nearly zero when not in use. Humans have this problem of needing to consume a large amount of resources for 18-24 years with very little useful output during that time, and have to be kept running 24/7 otherwise you lose your investment. And even then there is a lot of risk they are going to be gibbering idiots and represent a net loss of your resource expenditure.

For this I have a modern Modest Proposal they we use young children as feed stock for biofuel generation before they become a resource sink. Not only do you save the child from a life of being a wage slave, you can now power your AI data center. I propose we call this the Matrix Efficiency Saving System (MESS).

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tlb14 hours ago
Aerroon12 hours ago

>Is there an AI system with functionality at or equal to a human brain that operates on less than 100W?

Obviously not equal to a human brain, but my GPU takes about 150W and can draw an image in a minute that would take me forever to replicate.

wongarsu14 hours ago

Obviously we don't have AGI so we can't compare many tasks. But on tasks where AI does perform at comparable levels (certain subsets of writing, greenfield coding and art) it performs fairly well. They use more power but are also much faster, and that about cancels out. There are plenty of studies that try to put numbers on the exact tradeoff, usually focused more on CO2. Plenty that find AI better by some absurd degree (800 times more efficient at 3d modelling, 130 to 1500 times more efficient at writing, or 300 to 3000 times more efficient at illustrating [1]). The one I'd trust the most is [2] where GPT4 was 5-19 times less CO2 efficient than humans at solving coding challenges

1: https://www.nature.com/articles/s41598-024-54271-x?fromPaywa...

2: https://www.nature.com/articles/s41598-025-24658-5

Majromax14 hours ago

I did some math for this particular case by asking Google’s Gemini Pro 3 (via AI studio) to evaluate the press release. Nvidia has since edited the release to remove the “tons of copper” claim, but it evaluated the other numbers at a reported API cost of about 3.8 cents. If the stated pricing just recovers energy cost, that implies 1500kJ of energy as a maximum (less if other costs are recovered in the pricing). A human thinking for 10 minutes would use sbout 6kJ of direct energy.

I agree with your point about induced demand. The “win” wouldn’t be looking at a single press release with already-suspect numbers, but rather looking at essentially all press releases of note, a task not generally valuable enough to devote people towards.

That being said, we normally consider it progress when we can use mechanical or electrical energy to replace or augment human work.

jasomill10 hours ago

While I don't know how more or less efficient it is, WolframAlpha works well for these sorts of approximations, and shows its work more clearly than the AI chatbots I've used.

Gravityloss15 hours ago

I think this is exactly the thing that should be done by a person without AI, to check what AI is writing.

brookst15 hours ago

That can be true while also seeing value in using an AI to sanity check human-generated claims.

franktankbank15 hours ago

Nah just spin up an agentic ai proofreading agent on the cloud.

CamperBob213 hours ago

Nobody on HN is a bigger AI stan than I am -- well, maybe that SimonW guy, I guess -- but the truth is that problems involving unit conversions are among the riskiest things you can ask an LLM to handle for you.

It's not hard to imagine why, as the embedding vectors for terms like pounds/kilograms and feet/yards/meters are not going to be far from each other. Extreme caution is called for.

zahlman12 hours ago

That sounds like the sort of thing I'd expect them to be good at. What goes wrong?

CamperBob212 hours ago

I edited the post with a speculation, but it's just a guess, really. In the training data, different units are going to share near-identical grammatical roles and positions in sentences. Unless some care is taken to force the embedding vectors for units like "pounds" and "kilograms" to point in different directions, their tokens may end up being sampled more or less interchangeably.

Gas-law calculations were where I first encountered this bit of scariness. It was quite a while ago, and I imagine the behavior has been RLHF'ed or otherwise tweaked to be less of a problem by now. Still, worth watching out for.

zahlman12 hours ago

> In the training data, different units are going to share near-identical grammatical roles and positions in sentences.

Yes, but I would also expect the training data to include tons of examples of students doing unit-conversion homework, resources explaining the concept, etc. (So I would expect the embedding space to naturally include dimensions that represent some kind of metric-system-ness, because of data talking about the metric system.) And I understand the LLMs can somehow do arithmetic reasonably well (though it matters for some reason how big the numbers are, so presumably the internal logic is rather different from textbook algorithms), even without tool use.

kergonath15 hours ago

It’s one of the useful functions of an engineer.

potato373284214 hours ago

It's almost always the engineers, analysts and MBA spreadsheet pushers and other people removed from the physical consequences outputting these mistakes because it's way easier to not notice a misplaced decimal or incorrect value when you deal in pure numbers and know what they "should" be than you are the person actually figuring out how to make it happen the difference between needing 26666666.667 and 266666666.667 <units> of <widget> is pretty meaningful. Engineers don't output these mistakes as often as analysts or whatever because they work in organizations that invest more in catching them, not because they make them all that much less.

Whether talking weight or bulk a decimal place is approximately the difference between needing a wheelbarrow, a truck, a semi truck, a freight train and a ship.

kergonath13 hours ago

Around here, asking "does this number make sense?" when coming across a figure is second nature, reinforced since early in engineering school. The couple of engineers from the US that I know behave similarly, which makes sense because when your job is to solve practical problems and design stuff, precision matters.

> difference between needing 26666666.667 and 266666666.667 <units> of <widget> is pretty meaningful

To be fair, that’s why we’d use 2.6666666667e7 and 2.66666666667e8, which makes it easier to think about orders of magnitude. Processes, tools and methods must be adapted to reduce the risk of making a mistake.

Jblx211 hours ago

>why we’d use 2.6666666667e7 and 2.66666666667e8

Engineers prefer (wait for it) "Engineering Notation": 26.67e6 and 266.7e6.

https://en.wikipedia.org/wiki/Engineering_notation

jandrewrogers14 hours ago

These kinds of errors are not rare in the media.

Even among engineering fields routine handling of diverse and messy unit systems (e.g. chemical engineering) are relatively uncommon. If you work in one of these domains, there is a practiced discipline to detect unit conversion mistakes. You can do it in your head well enough to notice when something seems off but it requires encyclopedic knowledge that the average person is unlikely to have.

A common form of this is a press release that suggests a prototype process can scale up to solve some planetary problem. In many cases you can quickly estimate that planetary scale would require some part of the upstream inputs to be orders of magnitude larger than exists or is feasible. The media doesn't notice this part and runs with the "save the planet" story.

This is the industrial chemistry version of the "in mice" press releases in medicine. It is an analogue to the Gell-Mann amnesia effect.

bradfa13 hours ago

With a higher voltage you can reduce your copper needs by a substantial amount. Seems if copper cost was a concern this would be what these data centers would do.

sidewndr4613 hours ago

Agreed. I was kind of surprised to see 54 VDC mentioned. I am assuming this is low enough to meet some threshold for some kind of safety regulation. In other words, it doesn't shock you just 220 VAC would. I'm not entirely convinced of that however as it turns out bus bars are really dangerous in general. A 54 VDC bus bar won't shock you, but if you drop even a paperclip between the bus bar and a metal part that is grounded it basically disappears instantly in a small blast of plasma. The injury from that can be far worse than any shock you'd receive.

bradfa12 hours ago

My experience has been that SELV (safety extra low voltage, less than 60V peak and less than 240VA) is considered safe and anything exceeding that needs certain levels of protection.

But bus bars generally should be protected regardless of voltage as they carry currents from high current capacity sources so even a lower voltage can be a safety concern.

Many server power supplies can take AC or DC input, with the DC input in the 300-500V range as this is comparable to the boost voltage for the AC power factor correction circuit. I just assumed most data centers using DC would be distributing around 400V within each rack.

hireshbrem15 hours ago

I wonder how many 'innocent' inaccurate data is taken by journalists to use for their agenda. I think this happens a lot in the age of AI.

JohnMakin11 hours ago

Efficient markets!

tlb15 hours ago

Checking the arithmetic in every paper published seems like an good use case for LLMs. Has someone built a better version than uploading a PDF to ChatGPT and asking it to check the arithmetic?

ironbound15 hours ago

LLM's are why we're in this mess, they can't do math or count r's

gordonhart15 hours ago

Modern reasoning models are actually pretty good at arithmetic and almost certainly would have caught this error if asked.

Source: we benchmark this sort of stuff at my company and for the past year or so frontier models with a modest reasoning budget typically succeed at arithmetic problems (except for multiplication/division problems with many decimal places, which this isn't).

RobotToaster15 hours ago

Interesting, how have you found they have been performing at more complex things like calculus and analysis?

speedgoose15 hours ago

It’s on the front page of HN once in a while.

literalAardvark14 hours ago

They can't do math?

ChatGPT 5.2 has recently been churning through unsolved Erdös problems.

I think right now one is partially validated by a pro and the other one I know of is "ai-solved" but not verified. As in: we're the ones who can't quite keep up.

https://arxiv.org/abs/2601.07421

And the only reason they can't count Rs is that we don't show them Rs due to a performance optimization.

ironbound13 hours ago

You can feed it the Hodge Conjecture for all I care, the current algorithms are a joke and without real breakthroughs your just generating left to right text with billions in hardware.

literalAardvark10 hours ago

Guess frontier math and programming are just left to right text then.

nine_k15 hours ago

An LLM usually has a powerful digital computer right in its disposal, and could use it as a tool to do precise calculations.

brookst15 hours ago

More accurate to say they can’t see r’s. They process language but not letters.

UqWBcuFx6NV4r14 hours ago

Yes, yes. We’ve all seen the same screenshots. Very funny.

Those of us who don’t base our technical understandings on memes are well aware of the tooling at the disposal of all modern reasoning models gives them the capability to do such things.

Please don’t bring the culture war here.