There's a few other things in the hardware that would bring up issues:

*Battery- smaller form factor, smaller battery, less life. People complain about that already
*camera- is there any place to put a camera on there that isn't going to be blocked by write hair or inconvenient to take a picture with? Can you see the screen to see the image? is it easy to hold your arm steady enough?
*Text input- voice recognition isn't there yet, and even when it is you don't always want to be public with your messages. How do you type on one quickly?
*Is there enough physical room for everything?
*Heat- if we do all that in a watch, how hot will it get? Will it become a safety hazard or uncomfortable to wear?
*Power- even if everything works, a phone can have the same stuff and more, due to form factor. So why would you limit yourself to the watch?

Actually, the key thing for them is "cheap". They need to keep costing sub-$1k missiles in the ballpark of these Iron dome systems - the more, the better. They might as well just omit the warheads to save money and increase range. Every $50k shot Israel fires with those systems costs 25 Israelis' annual tax contribution to the IDF. Every $55m system they deploy costs 27.500 Israelis' IDF tax contributions.

Palestinians are poor, but they're not *that* poor that they can't leverage those kind of lopsided financial ratios.

Two seconds in a year!?! That means in a mere 30 years you'll have to adjust it by a minute. In your life you'll have to adjust it 3 times! DO you know how much effort and time you'll save by buying a $10,000 high end mechanical watch? You'll only have to adjust it once- that's got to save you 2 minutes over the course of your lifetime. Isn't 10K a small price to pay for that?*

*Math void if anything heavier than a feather ever touches it, as it may break the delicate alignment of gears.

Even more real answer- I'm in the subway. I'm not getting that call/text because the signal isn't reaching me through 10m of solid earth.

* Displace smart phones/dedicated GPSes used for turn-by-turn directions (visual and audio) while driving. It's going to be great for motorcycle users. I'm not sure yet whether it will be legal for this use.

So could smartphones, at no additional difficulty. In fact they'll do so better if you have a bluetooth earpiece, as the audio will be routed right to your ear. There's nothing here a watch will do better than a phone. (There's also good reasons for continuing to use the dedicated GPS, as they tend to lose signal less, have maps predownloaded in case you go to an area with spotty internet, and have better databases of nearby locations. But I can understand wanteing to ditch it).

It will make the policeman's job more difficult by allowing drivers to check their emails/texts while driving without it being obvious to an observer.

Here's an idea- on the extremely rare occasion you actually have to deal with the police, wait 10 fucking minutes to look at your texts. Also, if you need to deal with the police more than once every 5 or 6 years, take a good hard look at what you're doing wrong with your life.

Provide quick updates to stock/commodity traders who are on the go or not near a desktop/laptop.

So does a smartphone, with a better UI, and more screen space for easy access to information

Allow joggers to skip songs without carrying their smartphones in their hands.

Or they could use voice control. But I doubt holding it in their hands or fishing it out of ones pocket is really all that much worse than trying to fuck around with your watch while jogging. In fact I would bet either of those are easier.

Yeah, still no valid use cases for a smartwatch.

I can't help but picture a sign on the door at the exit of an airport in Israel. It reads "Thank-you for not stirring up ancient inter-tribal conflict".

Now I can't help but think of this excellent video :)

Using a nuclear device at high altitude? You do know what happens if you do that, right? That one test bomb knocked out street lights and long distance phone service nearly 1000 miles away and took out a third of all satellites in orbit around Earth at that point in time.

No, in the case of Iron Dome, that's only PR too. They're shooting $50k+ missiles at $800 rockets. Even after factoring in that Israel's per-capita GDP is 20 times that of Palestine's, that's still a losing proposition, even *if* they had a 100% hit rate (which this article is suggesting it's anything-but) and assuming that you get the launcher, radar, etc for free instead of the actual $55 million per unit. It's in Palestine's best interests that Israel deploy as many of them as possible and try to shoot down every last rocket, because every shekel they spend on Iron Domes and missiles is a shekel they don't spend on jets, tanks, and bombs.

I did not use the words efficiency or efficiency. You might want to work on your reading ability. It's not able, and you're not reading.

Sure, if your only goal is efficiency. But if it is, you're boring.

I just know there's a homeopathy joke in there somewhere...

Well, no. Not unless you can account for ballistics, and the drop zone for your projectiles. But perhaps you should be permitted to use a tethered net launcher.

Or any public property. Whether the restrictions on line-of-sight are reasonable is a whole other discussion (my thought is "maybe") but public lands belong to all of us. As always, the thing must be operated in a manner which does not represent a realistic risk to others.

... the greater your capacity, the less cycle life matters. If you want an EV that battery that will run a 250Wh/mi vehicle for an average 20 miles a day for 15 years, then you want it to cycle through about 30MWh. If you use a 100 mile (25kWh) battery pack, then that's 1100 cycles. If you use a 200 mile (50kWh) battery pack, then that's 550 cycles. If you use a 400 mile (100kWh) battery pack, then that's a mere 275 cycles. Actually, the improvement is even better than that in the real world, because the greater your capacity vs. how far you're actually driving, the more you can cycle the cells through a less destructive state of charge range rather than doing deep discharges.

A lot of people picture battery packs in EVs backwards, they think that things like hybrids stress the packs the least, PHEVs moderately, and EVs the worst. But it's reversed. If you look at how big hybrid packs are vs. how much electric range they hold, you'll see that they're disproportionately large, even after you factor in any differences in Wh/kg. The reason is that because hybrid packs get cycled so much, they have to keep the cycling in a very narrow state of charge range, only allowing shallow discharges. So if you only have a narrow discharge range, you have to make your pack bigger to make up for it. EVs can discharge through much more of their pack because they need fewer total cycles and only rarely go down toward the lower end of their allowable discharge range. Some EVs also let you limit the max that your pack charges up to to further extend lifespan (it's usually destructive both to use the very top end and the bottom end of the discharge range).

1024 mAhg1 is excellent capacity even vs. brand new graphite or amorphous carbon, about 3x as much as graphite's maximum. Silicon's theoretical max is 8-10x that of graphite, but the main problem with it is durability, it tends to tear itself apart on loading. There are silicon anodes in some newer li-ion cells on the market, but the tech is in its infancy.

That said, the real papers you want to be on the lookout for are cathode improvements, there's a lot more potential for volume/mass reduction there than in the anode. But it seems to be a more difficult challenge. Getting a 3x improvement in anode density is absolutely not the same a getting a 3x improvement in battery life.

Commercial li-ion battery energy densities have continued to improve during that time period, including the commercial introduction of cells with silicon anodes. Of course, silicon anodes are a new tech, so there's a great deal of room for improvement, which probably won't come close to "maxing out" for a decade or more.

Of course, that said, this article is your typical fluff piece following the guidelines of fluff science reporting.

1. Present an oversimplified version of one technology challenge that may or may not address the biggest issue and certainly doesn't address all of them - but don't mention that.
2. Introduce an outside-the-establishment loner with a passion - or at least someone you can try to present as "outside the establishment" and glaze over anyone who helped him.
3. Loner gets a "vision" based on some everyday activity
4. Present their solution and make it out to be a huge revolution that will certainly solve all our problems - if they can only get corporate backing / funding!

I think these sort of articles hurt the image of science because people read them, think "OMG, all our problems are solved!", then when everything's not solved afterward, fail to trust science in the future. For example, in this case, the most important element to improve is the cathode, not the anode. And cathode improvements are less common and usually less major than anode improvements. There's also tons of different anode improvements out there in various stages of research. Pretty much all of the silicon ones get way better than graphite or amorphous carbon.

That doesn't mean that this isnt an important paper - actually, from looking at it, it looks pretty good. It's just not "all that".

BTW, anyone know how credible this journal is? I see it's hosted on Nature.com but not part of Nature, and I tried to find an impact rating for it but couldn't.