waylandsmith

waylandsmith t1_j60w9pt wrote

A lunar space elevator is possible, but would be quite different than one that could be built on Earth. But the moon's lower gravity makes a lot of the benefit of a space elevator moot. A lack of atmosphere on the moon also makes some sort of railgun launch possible and economical, at least for cargo.

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waylandsmith t1_j5xtcqe wrote

Naively, on paper, yes. Launching from the Moon vs Earth saves you about 9km/s in delta-v, more than making up for the 4km/s to slow down, and then another 2.4km/s to actually land on the moon. But the problem is a lot more complicated than that. Without aerobraking, the propellant needed to land would need to be sent with the spacecraft on its entire journey. Fuels that are stable for long, long journeys are typically significantly less efficient than those that can be refreshed/topped-up until the moment of launch, so more of that stable fuel is needed, requiring more launch fuel to get it into space. The delta-v budget would be turned on its head and the vast majority of it would be needed to be spent right at the end, instead of at the beginning. And this, of course, ignores the problem of how to get the spacecraft onto the moon and the payload back to Earth.

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waylandsmith t1_iya5h90 wrote

With ISO paper sizes, the loophole is easy: Buy A3 paper, fold it in half and cut along the fold for 2 pieces of A4. A3 banned? Fold A2 in half, cut, now you have 2 pieces of A3. Another loophole? Most printed paper is only one sided! Turn it over and now you have a blank page!

But seriously, Chinese government, you're making yourself look idiotic. If your own people can make you so afraid of a piece of blank paper that you need to try to ban the sale of it, you've lost.

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waylandsmith t1_iwm2x0o wrote

You should read up on what rare earth metals are. Lithium isn't one of them. They're on the opposite side of the product table. It's not even "rare" in the conventional sense. It ranks between lead and cobalt in abundance in the Earth's crust. Finally, it takes up only about 2.5% of the weight of a typical EV battery. Yes, we're currently in short supply during the rapid run-up in the EV market but it's also nearly perfectly recyclable, meaning eventually exhausted EV batteries will become a major source of lithium in new ones. That is, unless we move to another battery chemistry by then!

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waylandsmith t1_iwiyrdv wrote

Oh, RTE means "Round Trip Efficiency". The paper's abstract doesn't make clear if this is a theoretical number from their numerical model (aka best case), or measured efficiency (real world). And ya, 77% is terrible compared to batteries, but possibly still useful in cases where you have so much overproduction at zero cost (really only solar) that it's still useful to throw out 1/4 of the energy.

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waylandsmith t1_iwb6ght wrote

Nope. Neutron stars exist in a narrow window of masses and densities and these characteristics have been confirmed in observations of them, at least the sort that we can detect (ones that are pulsars). The neutron star itself does have some structure, though, with various layers containing slightly different densities, the different forms being called "nuclear pasta". It has a gnocchi, spaghetti, lasagna, anti-spaghetti, and finally a 'swiss cheese' layer.

I'm glad that scientists get to indulge in whimsical naming once in a while. (the truth and beauty quarks got re-named top and bottom unfortunately).

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waylandsmith t1_iwau9m0 wrote

This is an interesting time to be asking that question, considering something that was just observed.

>The hypermassive star was produced by the merger of two smaller neutron stars. Normally such collisions result in neutron stars so massive that they collapse into a black hole almost instantaneously under their own gravity. But the latest observations revealed the monster star hovering in view for more than a day before it faded out of sight.

So, according to the observation, two neutron stars (which are always quite close to the critical mass for a black hole) merged, bringing the total mass much higher than the needed limit, but it took a significant amount of time for the observable neutron stars to 'fade away' into the black hole.

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waylandsmith t1_iwat4ne wrote

I'm pretty sure you've misunderstood. I can see there being some ambiguity from the wording of the question, but the topic flair on the question is "paleontology", not "genetics" or "biology". I think it's safe to say they're asking about "having" DNA in the sense of having samples from it, not "having" DNA as in sharing DNA with those species.

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waylandsmith t1_iuigr1w wrote

I worked for 8 years at a software company working with reformers in the medical system trying to fix how the active learner and "resident" system works. It was pretty disturbing to learn how things work at a typical learning hospital. Especially frightening was discovering that "evidence based medicine" is (was?) still a relatively fringe idea that there was large resistance to. The system sucks. I live in Canada where the learning system is a bit better, but we have a significant brain drain problem where Canadians attend a relatively affordable medical program here and then move to the states to earn the big bucks in the private medical system.

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waylandsmith t1_iu3xmc8 wrote

Yep, I pretty much had the same attitude, into my 40s never had a bad breakup with a partner, never regretted a relationship, friends with most my exes. But with this one, blew through a bunch of red flags but they really wanted to stay with me, so figured what's the worst that can happen? I almost didn't survive the aftermath of the breakup. To rest of you with a similar experience, I'm really sorry and hope you recover.

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