It's the same reason why many of the oppose geothermal power, keeping Hawaii reliant on burning oil for most of its electricity. Also why there's opposition to even trying to redirect lava flows as most countries do when their people are threatened (with a number of successful redirects having been achieved).

Apparently Pele wants people to be ignorant of the cosmos, to destroy the climate, and to lose their dearest possessions without putting up a fight.

I get 1 new recruiter request per month. What typically follows is spamming of job offers because one keyword matched in their database. Such as "programming". I've had some pretty interesting offers once in a while. Perhaps not interesting enough to jump ship after all the advantages I have for working 18 years in the same house, but some came very close. But on the average of 10-15 offers a month, most are totally irrelevant to what my profile lays out in terms of specialties and experience.

The problem boils down to the recruiters not understanding the core technologies they're being tasked as manning. So they shoot all around hoping for a positive hit because they want their fees and will go as far as sharing their fees with a sign-in bonus.

Can you imagine a 500$ sign-in bonus would have an 18 year veteran jump ship?

If you can't be bothered creating an account or resetting your lost password, you can forget about any meaningful offer.

I've seen plenty of work on accelerator-drive heavy isotope reactors but nothing for light isotope reactors like lithium. Accelerator driven heavy isotope reactors still deal with many of the problems of conventional fission reactors - they're greatly improved in many regards, but still problematic (you still have some plutonium, you still have some fuel availability/cost limitations, you still have some long-lived waste, you still have some harder to shield radiation, you still have a wide range of daughter products making corrosion control more challenging, etc - just not to the degree of a regular fission reactor). A light isotope reactor using lithium would virtually eliminate all of these problems. And it has a higher burnup ratio, which is of course critical for space uses.

And while everything I've seen about past improvements in accelerator efficiencies and spallation process improvements, and what's being worked on now, suggests no limit any time soon on neutron production efficiencies - at least that's how it looks from the papers I've read. Plus, even if efficiencies couldn't be improved any further (there's not that much further one needs to go), one could hybridize a heavy isotope and light isotope reactor, using a heavy isotope target as a neutron multiplier to bombard the lithium. You'd require significantly reduced quantities of heavy isotopes relative to a pure heavy isotope reactor, and most of the energy from the lithium side could be as mentioned captured without Carnot losses, which is a big bonus. Any non-thermalized neutrons of sufficient energy would produce tritium as a byproduct, which of course would be a value-added product - in fact, given that the tritium-breeding reaction with 7Li and a high energy neutron yields a lower-energy neutron, the thermalization could potentially be done via tritium breeding in the first place. And tritium is a valuable product whether one has interest in D-T fusion or not.

I just think it's weird that I've not come across any work on a lithium-based accelerator-driven spallation reactor, and was just wondering if there's a reason for that. It certainly looks appealing to my non-expert eyes. I mean, it looks even cleaner and more fuel-available than D-T fusion, and looks closer to being viable on a full-system perspective. Versus accelerator-driven heavy isotope fission you get less power per neutron (about a quarter as much), of course, even accounting for Carnot losses in the former - but that's not what matters. Cost is what matters, and if you're eliminating the use of super-expensive fuel, not producing any costly-to-manage waste, have no incident radiation, no proliferation concerns, etc, you're completely changing the cost picture - without even considering the possible joint production of saleable tritium.

I own a 2001 Honda Insight hybrid modified to be a PHEV and plugged in nightly to charge on geothermal power.... and a Ford Ranger ;) The "why" is obvious, because I have regular needs to carry big heavy things, now that I own land in the countryside. Back when I had no such need... I didn't own any such vehicle.

I guess it's hard for him to imagine that a woman would have a need to carry large and/or heavy items?

And the crazy thing is, they did consult with male colleagues before publishing. The reviewer just assumed that because two women submitted a paper with a conclusion that he disagreed with, that it's specifically because they're women "making ideologically biased assumptions" who refuse to talk to men.

Oh hey, since we've got (assumedly) a lot of physics nerds on this thread, and because my mind hasn't suddenly stopped being curious about random topics even though I grew old: here's one of my more recent things that left me with unanswered questions:

One of the commonly cited tritium-generating reactions is 7Li+n(>2.466 MeV) -> 4He + 3H. But is 7Li not also capable of transmutation to 8Li via slow neutron capture? If so would that not yield a 16.004 MeV beta to 8Be, and then immediately into 2 alphas with an additional energy of 0.092 MeV? If so, is there not potential for a future nuclear reactor? Spallation currently yields neutrons for about 25MeV each. If one could cut that in half or less - which I don't see any laws of physics in the way, just improvements in accelerator efficiencies and the spallation process - could this not yield a net positive, using direct deceleration/capture of the beta to generate power without having to suffer Carnot losses? And if so, would that not be a very desireable reactor - nonproliferative, abundant fuel, harmless waste, high ratio of fuel to energy conversion, direct spacecraft thrust possibilities, etc? Or am I totally off base here?

Haha, my concept as a child was to have a buoyant container on wheels in a tube full of water that would rise up, roll down a ramp on the other side, and re-enter the tube through an airlock on the bottom.

Wish my dad had taken the time to tell me why it wouldn't work rather than just saying "perpetual motion is impossible".

Or, rather than all of physics being wrong, maybe they have an erroneous measurement setup.

That doesn't mean you shouldn't investigate anomalous measurements. But at this stage you shouldn't be writing fluff pieces with page after page of how much your new technology will change spaceflight. You should be publishing a paper with a name like "Measurement of anomalous thrust in a microwave apparatus operated in a hard vacuum" and trying to avoid the media insomuch as possible - and when you need to talk with them, trying to explain "we don't know what's going on... we have some theories but they're controversial... we need to do more testing." etc.

Small prop driven aircraft, ALREADY.

The market was almost nonexistent about five years ago but it's growing quite fast. Don't underestimate what the major and ongoing advances in motors, controllers, and batteries will bring in the future. There's many radically new technologies in the works to partially or completely electrify aircraft transportation, far beyond just electrically driven propellers.

I'd have trouble being whisked around town dangling from a drone under my command without also being in a superhero costume.

Seriously, in our modern age, how else would a superhero get around? A fast car? Pish.

The system is actually not that big. The batteries are small because, despite the weight of the plane, the distances traveled are very short; and electric motors pack a lot of power into a small package. Having it all built into the plane reduces ground delays, ground staff, and additional ground hardware. It's a "pushback and go" system, the pilot can move the instant he gets clearance to, he doesn't have to wait for anyone else. It's estimated to save about 2 minutes over using tugs, which may not sound like a much, but each flight at the gate represents about $100k worth of revenue, so squeezing an extra flight in every couple days is a lot of money.

Ultimately they want to turn it into a fully automated airport traffic flow, where each plane moves from the runway to the gate and vice versa in a fully automated, optimized manner.

"Fast" is not an issue. Electric motors have a much better power to weight ratio than combustion motors, and li-ion batteries have no trouble feeding it. The reason things like solar impulse fly slowly is to reduce air resistance and thus minimize their power consumption needs.

Batteries have advanced tremendously in the past several decades and show no signs of slowing down. The transition of air travel will be more difficult and longer in the making than that of ground travel, mind you.

Before ICBMs became a reality, nuclear-powered planes were significantly researched. Probably the craziest was Project Pluto, whose concept was to have an open to the air nuclear core inside a ramjet housing, acting as the heat source instead of combusting fuel. The unmanned craft was designed to be able to fly around for months at a time holding numerous atomic bombs. When given orders to attack it would have bombed Soviet cities... then with its cargo spent, continued the rest of its lifespan flying low over Soviet territory damaging everything its path with sonic booms and the radioactive plume spewing out the back. Then when finally shot down or out of power, it'd crash as a dirty bomb in Soviet territory.

The engine was actually tested on a railcar, but there were way too many concerns about the craft, and the advancement of ICBMs just seemed a better route. Among the many concerns was that the US didn't want the Soviets to feel that they had to develop a similar such craft as a countermeasure.