Studies have all come out clean on pacemakers and mmWave. No detectable interference in the hardware or on an EKG while in a mmWave scanner.
I could imagine other conditions potentially but pacemakers have been ruled a non issue for mmWave by academic studies (albeit I can understand still exercising caution despite that).
Tbh I'm not sure but they've done accelerated dosage testing to simulate long term use by repeatedly exposing people to use of the machine over a more frequent period of time.
But mmWave really just is not dangerous. Current generation 5G cellular and WiFi standards are mmWave and they are just as harmless.
Molecular damage just starts showing up with THF/terahertz emissions band but mmWave is in the EHF and is has more than 10x the wavelength of THF (i.e. it is far wider/more gentle than THF). In a very real sense mmWave can't even interact with most of the molecules in your body.
mmWave can interact with the water in your body but at the levels it's being used it's only really useful for seeing the water. You'd needs orders of magnitude more powerful emissions than what these scanners use to actually cause damage at that frequency.
i.e. It's the difference between using the flashlight on your phone to see in the dark and using the concentrated light from solar-thermal heliostats to boil water or heat molten salt. No matter how hard you try, your flashlight is never gonna boil water.
The distinction is that what they are doing for Webb is trying to dissipate small amounts of heat that would warm up sensors past cryogenic temperatures.
Like on the order of tens or hundreds of watts but -100C.
Dissipating heat for an AI datacenter is a different game. A single AI inference or training rack is going to be putting out somewhere around 100kW of waste heat. Temps don't have to be cryogenic but it's the difference between chiselling a marble or jade statue and excavating a quarry.
It's worth noting that the EACTS can at maximum dissipate 70kW of waste heat. And EEACTS (the original heat exchange system) can only dissipate another 14kW.
That is together less than a single AI inference rack.
And to achieve that the EACTS needs 6 radiator ORUs each spanning 23 meters by 11 meters and with a mass of 1100 kg. So that's 1500 square meters and 6 and a half metric tons before you factor in any of the actual refrigerant, pumps, support beams, valve assemblies, rotary joints, or cold side heat exchangers all of which will probably together double the mass you need to put in orbit.
There is no situation where that makes sense.
-----------
Manufacturing in space makes sense (all kinds of techniques are theoretically easier in zero G and hard vacuum).
Mining asteroids, etc makes sense.
Datacenters in space for people on earth? That's just stupid.
Your calculations are based on cooling to 20c, which is exponentially harder than cooling to 70c where GPUs are happy. Radiators would be roughly 1/3 the size of the panels for 70c.
I get that vacuum is a really good insulator, which is why we use it to insulate our drinks bottles. So disposing of the heat is a problem.
Can't we use it, though? Like, I dunno, to take a really stupid example: boil water and run a turbine with the waste heat? Convert some of it back to electricity?
It's a good question, but in a closed system (like you have in space) the heat from the turbine loop has to go somewhere in order to make it useful. Let's say you have a coolant loop for the gpus (maybe glycol). You take the hot glycol, run it through your heat exchanger and heat up your cool, pressurized ammonia. The ammonia gets hot (and now the glycol is cool, send it back). You then take the ammonia and send it through the turbine and it evaporates as it expands and loses pressure to spin the turbine. But now what? You have warm, vaporized, low pressure ammonia, and now you need to cool it down to start over. Once it's cool you can pressurize it again so you can heat it up to use again, but you have to cool it, and that's the crux of the issue.
The problem is essentially that everything you do releases waste heat, so you either reject it, or everything continues to heat up until something breaks. Developing useful work from that heat only helps if it helps reject it, but it's more efficient to reject it immediately.
A better, more direct way to think about this might be to look at the Seebeck effect. If you have a giant radiator, you could put a Peltier module between it and you GPU cooling loop and generate a little electricity, but that would necessarily also create some waste heat, so you're better off cooling the GPU directly.
I think I get it. If we could convert 100% of the waste heat into useful power, then all good. And that would get interesting because it would effectively become "free" compute - you'd put enough power into the system to start it, and then it could continue running on its own waste heat. A perpetual motion machine but for computing.
But we can't do that, because physics. Everything we could do to generate useful energy from waste heat also generates some waste heat that cannot be captured by that same process. So there will always be some waste heat that can't be converted to useful energy, which needs to be ejected or it accumulates and everything melts.
What do you do with the steam afterwards? If you eject it, you have to bring lots of it with your spacecraft, and that costs serious money. If you let it condensate to get water again, all you did is moving some heat inside the spacecraft, almost certainly creating even more heat when doing that.
However there are workarounds. People are talking like the only radiator design is the one on the ISS. There are other ways to build radiators. It's all about surface area. One way is to heat up a liquid and then spray it openly into space on a level trajectory towards a collecting dish. Because the liquid is now lots of tiny droplets the surface area is huge, so they can radiate a lot of heat. You don't need a large amount of material as long as you can scoop up the droplets the other end of the "pipe" and avoid wasting too much. Maybe small amounts of loss are OK if you have an automated space robot that goes around docking with them and topping them up again.
On this topic of ports/recomps there's also OpenGOAL [1] which is a FOSS desktop native implementation of the GOAL (Game Oriented Assembly Lisp) interpreter [2] used by Naughty Dog to develop a number of their famous PS2 titles.
Since they were able to port the interpreter over they have been able to start rapidly start porting over these titles even with a small volunteer team.
Lol yep. Emacs as the IDE, Allegro Common Lisp as the interpreter + HAL implementation, and GOAL itself being a Scheme-like.
Naughty Dog in general was actually a primarily Lisp studio for a long time. It was only in the PS3 era with Uncharted and The Last of Us that they switched to C++ because trying to maximise the performance out of a Lisp interpreter environment with the complexity the Cell Processors added on a time and cash budget simply wasn't feasible for them.
The Crash Bandicoot games were written in GOOL (Game Oriented Object Lisp) which they wrote prior to GOAL and the Jak and Daxter games. GOOL/Lisp of course was extremely important for the Crash Bandicoot legacy because by writing their own higher level interpreter they were given an excuse to through away the entire standard library that Sony gave them and start from scratch. That process allowed them to write a massively more performant stdlib and execution environment leading to Crash Bandicoot being able to support game environments an order of magnitude more complex than other games at the time could. And of course this allowed them to build in a system for lazy loading the environment as the player progressed through the levels which firmly cemented Naughty Dog in the video games history books.
Andy Gavin actually has an incredible blog site (including a 13 part series on Crash Bandicoot and a 5 part series on Jak and Daxter) that has over the decades documented the history of their studio's game development process and all the crazy things they did to make their games work on hardware where it really shouldn't have been able to with the tools they were provided.
Oh I should issue a minor correction. After talking with some people more familiar with it than me, Crash had a lot written in GOOL but it's not 100% GOOL like how Jak is 100% GOAL.
Instead it's mostly enemy AI and the like which are built in GOOL and the game itself is instead a more traditional systems language (I believe C++). So instead of 100% it's more like 40/60 which tbh is still quite good.
Absolutely. OpenGOAL really just set a new standard for what games preservation looks like.
It's incredible seeing the community taking a 25 year old game, modernising it with accessibility features and quality of life, and even creating entirely new expansions to the game [1].
Like beyond just keeping the game preserved on modern platforms, it's keeping the spirit of the game and the community attached to it alive as well in a way that it can continue to evolve and grow.
I can only pray that PS2Recomp makes this a fraction as accessible to other games from this era.
Oh and a similar project but on the nintendo side of the world is Ship of Harkinian by HarbourMasters [2] and the Zelda RE Team [3]. Zelda RET have half the Zelda games and are well on their way decompiling and reverse engineering the other half. And HarbourMasters have taken these decomps and used them as the groundwork for building comprehensive ports and remasters of these original games to a degree that fans could only dream that first party remasters and ports would attempt.
It's worth noting that the way Signal's architecture is set up, Signal the organisation doesn't have access to users' phone numbers.
They technically have logs from when verification happens (as that goes through an SMS verification service) but that just documents that you have an account/when you registered. And it's unclear whether those records are available anymore since no warrants have been issued since they moved to the new username system.
And the actual profile and contact discovery infra is all designed to be actively hostile to snooping on identifiable information even with hardware access (requiring compromise of secure enclaves + multiple levels of obfuscation and cryptographic anti-extraction techniques on top).
Perhaps you're right that they couldn't be compelled by law to reveal it, then! However, I can still find people on Signal using their phone number, by design. If they can do that, surely there is sufficient information, and appropriate means, for US state-side signals intelligence to do so, too. I don't think Signal self-hosts their infrastructure, so it wouldn't be much of a challenge considering it's a priority target.
Now, whether FBI and friends would be determined to use PII obtained in this way to that end—is a point of contention, but why take the chance?
Better yet, don't expose your PII to third parties in the first place.
Yeah it should be technically feasible to do "eventually" but it's non trivial. I linked a bunch of their blogs on how they harden contact discovery, etc. And of course you can turn contact discovery off entirely in the settings.
Settings > Privacy > Phone Number > Who can find me by number > Nobody
> And of course you can turn contact discovery off entirely in the settings.
I know right and that would keep you hidden from Average Joe, but not US government. The mechanism to match your account to your phone number remains in place.
If you aren't saving people's phone numbers in your own contacts, signal isn't storing them in group chats (and even if you are, it doesn't say which number, just that you have a contact with them).
Signal doesn't share numbers by default and hasn't for a few years now. And you can toggle a setting to remove your number from contact discovery/lookup entirely if you are so inclined.
They weren't though? Signal requires a phone number to sign up and it is linked to your account but your phone number is not used in the under the hood account or device identification, it is not shared by default, your number can be entirely removed from contact disovery if you wish, and even if they got a warrant or were tapping signal infra directly, it'd be extremely non trivial to extract user phone numbers.
In past instances where Signal has complied with warrants, such as the 2021 and 2024 Santa Clara County cases, the records they provided included phone numbers to identify the specific accounts for which data was available. This was necessary to specify which requested accounts (identified by phone numbers in the warrants) had associated metadata, such as account creation timestamps and last connection dates.
Yep however that only exposes a value of "last time the user registered/verified their account via phone number activation" and "last day the app connected to the signal servers".
There isn't really anything you can do with that information. The first value is already accessible via other methods (since the phone companies carry those records and will comply with warrants). And for pretty much anyone with signal installed that second value is going to essentially always be the day the search occurred.
And like another user mentioned, the most recent of those warrants is from the day before they moved to username based identification so it is unclear whether the same amount of data is still extractable.
I think that's a fair assessment on their part however it's worth noting that your phone number does not serve as your account ID. It can be used to look up an account but there are caveats to that.
The lookups go through a secure enclave, the system is architected to limit the number of lookups that can be done, and the system has some fairly extensive anti-exfiltration cryptographic fuckery running inside the secure enclave to further limit the extent to which accounts can be efficiently looked up.
And of course you can also remove your phone number from contact discovery (but not from the acct entirely) but I'm not sure how that interacts with lookup for subpoenas. If they use the same system that contact discovery uses, it may be an undocumented way to exclude your account from subpoena responses.
The rest of what they say however is pretty spot on. The priority for signal is privacy, not anonymity. They try to optimise anonymity when they can but they do give up a little anonymity in exchange for anti-spam and user-friendliness.
So of course the ending notes of "use a VPN, configure the settings to maximise anonymity, and maybe even get a secondary phone number to use with it" are all perfectly reasonable suggestions.
Others mention you must still register with a phone, although you can remove it from your account after you go through the username stuff? Usually HN is pretty good about identifying that the default path is the path and that opt-out like behavior of this means very little for mass usage.
It's not that you can remove it from your account entirely. Your account is still linked to that number. It's that you can remove the number from contact discovery.
And re: defaults the default behavior on signal is that your phone number is hidden from other users but it can be used to do contact discovery. Notably though you can turn contact discovery off (albeit few people do).
Which of those links actually say that your phone number is private from Signal? If anything, this passage makes it sound like it's the reverse, because they specifically call out usernames not being stored in plaintext, but not phone numbers.
>We have also worked to ensure that keeping your phone number private from the people you speak with doesn’t necessitate giving more personal information to Signal. Your username is not stored in plaintext, meaning that Signal cannot easily see or produce the usernames of given accounts.
Yeah WD-40 is good for cleaning up old grease or loosing up seized mates more than anything but pretty much as soon as you get it moving you want to clean it up, let it boil off, and then replace it with lithium grease.
Do not use canola oil for most lubrication tasks. You should almost always be using lithium grease.
Spray on white lithium grease works for most "architectural" or furniture uses (ex: door hinges, gas springs on chairs, garage door rails and chain, etc).
For anything constantly moving (ex: gearboxes or bearings) you want a more viscous lithium grease (ex: red n tacky or lucas xtra/green).
But in pretty much every situation (on land) you want to be using a form of lithium grease if you want to actually keep the interface lubricated.
I could imagine other conditions potentially but pacemakers have been ruled a non issue for mmWave by academic studies (albeit I can understand still exercising caution despite that).
reply