grkvlt

OK, so 235 kg of U_235 has the same number of fissile units (N atoms = 1000 x N_a) as 5 kg of D-T has of fusible units (2N atoms of combined weight 5 amu, or 1000 x N_a pairs) so (ignoring the N_a for now) one kg of U_235 gives 200 MeV / 235 = 0.85 MeV and the D-T fusion gives 17 MeV / 5 = 3.40 MeV

So, yeah, that's exactly four times the energy per kilogram. Now, why couldn't they just say THAT on the web page instead of the confusing and meaningless "this energy is 3-4 times more powerful than that energy" nonsense? But, thanks 'mikeash for clearing that up for me!

Except for the fact that the sort of person who cannot come up with USD 400 in cash is also the sort of person who has a poor credit rating and no credit cards, and most likely their peer group of friends and family are in exactly the same situation. This is the same sort of tone deaf advice that rich people give about starting your own company - "Why can't these poor people just borrow a few hundred thousand dollars from the family trust fund like I did, they must just be shiftless and lazy" - and should be dismissed in the same way. I suspect the author has neither been short of money in their life, nor met anyone else who was...

But even that is pretty vague, since a single Uranium atom fission event releases about 200 MeV of energy, whereas most of the Hydrogen/Deuterium/Tritium/Helium/etc. fusion pathways release around 10% of this per fusion event: D + T -> He fusion gives 17 MeV, 4 p -> He gives 27 MeV, D + D -> He is 12 MeV and so on. Now, the energy released per nucleon greater for fusion, but I'm not convinced that's a useful or intuitive metric?

I'd believe Lockheed Martin's CFR claims more if they didn't say things like this:

> Energy created through fusion is 3-4 times more powerful than the energy released by fission.[0]

Which is just confus(ed/ing) on a fundamental level... More Powerful energy? So each Joule from fusion is actually 3-4 times better than each Joule from fission, in some way? I really can't work out what they are trying to say here.

0. https://www.lockheedmartin.com/en-us/products/compact-fusion...

Maybe Exercise Tiger[0] w which was a rehearsal for the D-Day Normandy landings, where they created a replica of the beach landscape that would be encountered. Or there's Sindh Kalay[1] which is an Afghan village created in Norfolk, UK.

0. https://en.wikipedia.org/wiki/Exercise_Tiger

1. https://www.independent.co.uk/news/uk/this-britain/welcome-t...

Well, there's not a choice anymore - everyone HAS to go and see those other hundred monumental cathedrals, after Notre Dame went up in flames a month ago...

Yeah, a Petawatt is huge, there is nothing on earth (well, see next sentence) that can provide that sort of average power continuously. For comparison, 4PJ is basically the output of a kiloton nuclear weapon, so one second of a PW laser needs a nuclear weapon powering the thing.

Someone who wants to buy 100 of those airplanes, but knows that the safety option reduces the risk of incurring a $100 million total hull loss by less than one percent, thus saving less than the $100 million extra cost for the option? Obviously the numbers are different, but see the oft-quoted 'Fight Club' line about product recalls for similar logic.

> Delivering a plane with or without it to a customer had the same cost

Not exactly, surely. The ongoing/recurring costs to Boeing would be increased with the feature enabled - it's another thing that can go wrong and must be monitored, it changes support requirements and the overall software runtime complexity. I assume that would get factored in, somehow...

Also, in our CS lab anyway, theft of the shiny mouse pads had evidently been an issue in the past, and they were often glued or otherwise attached permanently to the desks.

But why? And who? No student back then (early 90s) could even dream of affording a SparcStation, which were the only workstations which used the mouse that needed the shiny mats.

We had various types of Sun machines in the labs, from the IPX and 5, up to dual processor 20s, and they needed an (expensive, maybe 200Mb) SCSI disk to boot from. Video was to a chunky high resolution (i recall OpenLook on 1152x900 grayscale was awesome, or the expensive option, 1280x1024 colour) monitor with RGB plus sync input using that weird 13W3 socket with the wee coax connectors inside. For networking you had to embrace the world of AUI media converters and so forth, which was just annoying. Anyway, all that stuff would have cost essentially the same as a nice Mercedes or a suburban house...

Maybe people used the muse mats as bird scarers? Perhaps they dropped too much LSD and just stared at the shiny pattern? Stealth teams of research assistants might be sent to fetch replacements for their professor's workstation, after running out of funding, but needing a new one having used his as a coffee mat and broken it? Or I suppose they could have been stolen by accident, not knowing what they were, by someone who was blinded by staring at the little laser under the mouse...

Indeed, what they (members of said sub-culture) all are is collectively different to, or in some way deviating too far from, whatever the current social norms, mores, or accepted majority cultural standards are. In this way, the group as a whole will appear unique compared to the majority of the population, who (usually) behave, dress and act in a (mostly) homogeneous way according to whatever the culture deems normal and within (somewhat) acceptable deviations.

Yes, and did you know most data centres add evil back doors to the machines you rent? The secret hardware is codenamed 'LOM' apparently...

I'd suggest that if you genuinely don't understand this sort of social thing instinctively, then you're probably on the autism/aspergers spectrum then. I really wasn't trying to be offensive towards you or anything, I just probably forgot some extra caveats... Basically, this sort of social reasoning is (usually) hard wired into your (typical) human being, and has been since prehistory. But mental disorders like autism seem to mess up social perceptions and interactions, masking these instincts. Fortunately, in that case, I've found it's possible to work around the issue by simply researching what the natural instincts and drivers are for the typical human, hence my suggestion of referencing an anthropology textbook.

It's pretty simple, and really not caused by people attempting to appear unique. There are two main factors: 1. All humans has a need to be accepted and approved of by their peers, 2. Humans also have an essentially identical neural architecture and a very similar set of likes and preferences to their peers. This results in groups of people with similar habits, clothes, and so on. The vast majority of humans normally want to fit in and conform, rather than be the odd one out in a group, see the entry on tribalism in any good anthropology textbook.

Also, anyone who claims not to understand this is either lying, engaging in some form of virtue signalling or has some sort of mental illness.

You would never say 'nominally', rather just 'nominal' to avoid confusion on noisy radio nets.

Interestingly, that's higher than the ppO2 at sea level, which is about 3 psi, or at ~5K feet (standard airliner cabin pressure) where it's 2.5psi, so they were still running at almost double the amount of oxygen available normally.

FYI, I think your terminology is slightly non-standard though - (UK) english normally would describe any device worn on the head which allows you to listen to audio as either 'headphones' or 'earphones' interchangeably, with the distinction you refer to being indicated by using the modifier 'in-ear' beforehand...

Also the cost differential that you seem to suggest exists between them is not apparent - I have seen examples of both form factors of bluetooth headphones as cheap as GBP 10.00 (or less) at a minimum, and you could spend way over GBP 500.00 on either kind if you so desired - you get what you pay for, though...!

it turns out that even mp3 encoding audio doesn't actually stop it being audible to other people nearby when played through speakers, the headphones on the other hand, mean only the wearer can hear it...

Most aircraft, really. That's why jet engine "air start" services are provided at most airfields and airports.

Because the truck carried flour and margarine, I was hoping the legend was going to be something about the fire started by the crash making a multi-ton sponge cake in the tunnel... Never mind...

Some of the recordings are unintentionally hilarious though, it turns out. When I looked at the history page, there were a bunch of times when Google seemed to think I was saying "b b b b b b b b b" repeatedly? Anyway, when I played the audio back, it seems my alarm clock's beeping had triggered the Google Assistant, which then obviously failed to understand the beeps!

And also, annoying for Echo device users, since the use of the word 'Alexa' will trigger the device, and thus mute/drop the volume so that you can't hear what is said next... I guess it could be worse, since the volume reduction means the device doesn't hear the command and try to execute it as well!

TBH, I don't understand why they couldn't add a circuit that checks if the microphone is being activated by the device's own speaker, and ignore it. Some sort of simple phase inverting circuit from the speaker that gets summed with the microphone input ought to do it. It's not exactly rocket science and they're doing complex phased-array/beam-forming stuff with the microphones already, so it's not like the engineers are idiots?

The problem seems to be there is no barrier to entry. Say what you like about Apple's app store, at least they have standards that are enforced, and to a certain extent Google as well. Windows, and the Microsoft app store, on the other hand, suffers the same problem of quality control and lack of curation as Alexa skills. There are some gems, and Amazon have put effort into making Alexa and the Echo devices useful out of the box with their default skills/commands. I've also never had issues with the smart home skills for various devices I have around the house. However, it's a telling statistic that there are over 50 'fart' skills, [0] half of which are rated at three stars or above.

And of course, although stricter curation and quality control would fix this, it would cut the number of skills down hugely, maybe even to 1% of the current size, so the app store looks tiny and people don't bother with the platform. See also Metcalfe's law [1] and network effects...

0. https://www.amazon.com/s?k=alexa+skill+fart&crid=2KFJ9DO3N51...

1. https://en.wikipedia.org/wiki/Metcalfe%27s_law

OR... the Internet and eBay have made watch collecting accessible and broken down a lot of the barriers to entry that used to exist, and were jealously guarded by gatekeepers. Yes, the likelihood is that most collectible watches now cost more, but the prices are probably much closer to a far value for the seller as well as the buyer due to the lessening of the huge information asymmetry that used to exist. Now, the watch you found in grandpa's attic when looking through his estate after he died can be researched and priced accurately using the Internet, and it becomes much harder for unscrupulous dealers to obtain it for peanuts.

> "Oh, these Rolex Milgauss watches with a certificate showing it was presented to your grandpa while he worked at CERN? [0] Yeah, there are loads and loads of them floating about, sorry, they're really common. If it was new, could be worth about five or six thousand pounds [1] but this is old, used and pretty well worn so probably only worth a couple of thousand quid, but I'll take it off your hands for GBP 2500.00 just to be nice, ok?"

0. https://onlineonly.christies.com/s/christies-watches-online-... - Estimate was from 10K to 14K and sold for GBP 17000.00

1. https://www.rolex.com/watches/milgauss/m116400gv-0002.html - Brand new from Rolex is GBP 6300.00

This is a strange thing to believe - fines exist for deterrence, not income - the purpose of a fine has failed if it ends up being paid, since it didn't deter the offender!

In the UK, for example, about GBP 80 million in speeding fines are issued each year. The annual police budget is GBP 12.5 billion though, so fines are a tiny 0.64% of that, hardly significant. Having said that, it looks like the road policing budget for 2018-19 is down by a large amount, from the GBP 200 million in 2016, to about GBP 90 million, so the fines would seem to cover most of that... Not sure what to make of that, now?

Well, there is their Polestar [0] performance division, which suggests there is such a market...?

0. https://www.volvocars.com/uk/cars/new-models/s60/variants/po...

Rockwell, I guess, at a stretch? Over 30 years ago they built the Space Shuttle...

You say today's marketing but this has been going on for a while now...! It's been at least sixty years since Vance Packard's [0] 1957 book, 'The Hidden Persuaders' was published, which was probably the first time the public learned about these tricks.

0. https://en.wikipedia.org/wiki/Vance_Packard

No, that is NOT what the 'tamper' is or does. See my (or various other) nearby comments where I describe the actual process, or just read the Wiki article linked in another comment...

Except that in a thermonuclear bomb, fission also occurs at the end as well as the start... The initial fission explosion starts off a fusion reaction, and then neutrons from the fusion process carry on to start another fission reaction, usually of the LEU 'tamper' encasing the bomb. In fact, a large proportion of the energy output is from this third stage fission reaction.