Gosh, I'm surprised nobody ever thought of that.

The Clarke comparison certainly grabbed my attention. My next question was "where can I find these works in English?" I see that one of the links above leads to English translations of a couple of stories.

Thanks for the tip!

First, I'd mod you up if I could for posting numbers.

Having said that, though, most of the efficiency breakdowns I've seen indicate that aerodynamic loss is higher than rolling-friction loss, especially at highway speeds -- drag goes up as the square of velocity.

Looking at the page you linked, I'm a bit surprised that it says rolling resistance is two to three times higher on "tar or asphalt" than on concrete surfaces. I didn't think there was that much difference between standard, mature asphalt surface and concrete, and I imagine friction on fresh asphalt or tar would be much higher than either concrete or older asphalt. The numbers for cruising on a concrete freeway are smaller by a factor of two or three.

From the other direction, that 10% of the energy is a theoretical maximum; it assumes that your recovery process cools the tires right down to ambient temperature, that it imposes no additional drag (due to its weight or its contact with the tire), and that it sustains no losses in its own operation. None of these three assumptions seems reasonable.

It would be up to the engineers at Goodyear (not Ford) to post the actual measurements of energy that they can reclaim, and the effects that this system has on overall vehicle efficiency. I haven't seen those numbers. I suspect that we won't, or that if we do, they won't be very impressive. I'd love to be wrong, though.

To which I say, "Derp". Not sure where in the world I pulled "Ford" from, but I probably ought to wash my hands.

A theory that ignores friction isn't especially interesting in this context.

Rolling friction is a pretty small contributor to energy loss for a moving car. Of this initially small amount of lost energy, some heats the road, and some heats the tire. As someone else observed below, the change in tire temperature is typically around 30 F, or 15-20 C, much less than a 10% change in absolute temperature. That means that a perfectly efficient heat engine could reclaim at most 10% of the thermal energy from the warm tires. In practice, the efficiency would be lower still.

Here's an infographic breaking down energy loss for an internal-combustion vehicle. Even if we assume that the electric vehicle has zero engine loss, rolling friction still represents at most maybe 20% of your energy loss. That means that you'd be reclaiming less than 2% of your total lost energy. In practice, considering the efficiency of the recapturing engine, it would probably be well under 1%; considering the added weight and mechanical loads of the recapture equipment, you might well end up losing net efficiency.

I'm not an engineer, but I have a basic understanding of thermodynamics. This story appears to be pitched at people who don't. If the engineers behind this want to convince people who know anything about physics or engineering, they're going to need something a lot better than this press release.

[clicks on link]

Rats.

I have to assume that any actual engineers at Ford understand Carnot efficiency, and that this is simply an effort on the part of marketing to generate social-media buzz. It's depressing, but not surprising, to see that they're succeeding.

Probably not.

First of all, the target wasn't matte black, so it was already reflecting a good bit of the incoming beam. I don't know what the IR reflectivity of the hood paint and underlying steel was at the laser's wavelength, so I don't know how much.

Second of all, while a mirror layer would be more reflective, it would also be thinner and less durable than a truck's sheet-metal. So, even if it's absorbing less energy, it's also less able to dissipate it.

It is interesting to consider the conflicting demands of stealth (low reflectivity, high absorbance) and laser-resistance (high reflectivity, low absorbance).

It's fun to imagine a target covered with corner-cube reflectors (which would direct the energy back toward its source), but if the laser emitter is a mile away, I don't know how much difference they'd make.

If you were into the whole "reading comprehension" thing, you might have understood a list of three alternatives to the action he took.

Or you might have gone ahead and done the clueless Anonymous Coward thing anyhow, as some sort of Kaufman-esque meta-performance-art schtick.

Perhaps that's something they should've thought about before they applied for that cushy Object Lesson opening.

How much vile and inexcusable behavior are you ready to tolerate "so taxpayers don't have to support them"?

I'm sorry that your children don't get to build their own meth lab.

No, actually, that's pretty close to the non-snarky truth. I was an avid chemistry hobbyist as a kid. Already in the 1970s it was getting harder to obtain some of the materials I wanted -- all the 1950's "chemical magic" books said to go to your pharmacy for nitric acid or carbon tetrachloride or white phosphorus, but the pharmacy was having none of that. Fortunately, I had science teachers who wanted to encourage my enthusiasm, and they arranged for me to order stuff through the schools. I managed not to do too much damage to the house, the environment, or my health.

Today? Schools and pharmacies are even more locked down, but now we've got search engines and e-commerce. On balance, it's probably easier to get stuff than it used to be. But with "chemistry sets" disappearing from the shelves, fewer kids are ever getting started in the hobby.

As for having "their imaginations torn from them", though, I think you're still way off-base. My kid spends a good bit of time on Minecraft and related online pursuits, but they still haven't come for her hot-glue gun, and her tower of miniature houses, characters, and gadgets continues to grow steadily. So do the stories that she's writing, both alone and in collaboration with former classmates. It would be cool if she took after chemistry or electronics like I did, I guess, but those aren't the only fields in which to become a maker.

And whatever you do, don't let anyone learn your True Name. If they have your True Name, they have power over you.

Seems to me that "outing users", in the form of leaking their personal info without consent, is what got Lenovo in trouble in the first place.

Well, heck. Now that we've mastered that pesky matter of grafting severed spinal cords, surely the optic nerve and other lesser bundles should be a piece of cake. So why not just do a brain transplant?

Anubis? Is that you?

Sounds a bit reminiscent of the Eschaton...

That can't possibly be accurate. Here's a paper reporting that total consumption of fully-refined silicon for chip manufacture in 1988 was 750 metric tons. I don't think increasing process efficiencies would have reduced that figure by four orders of magnitude since then...