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Cake day: June 18th, 2023

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  • If you’re getting into private jets, you should also know that brands have reputations even there.

    Gulfstream is a luxury brand within the private jet world. You can easily get a comparable product from Bombardier or Cessna Textron that performs equivalently, but only pay half as much operating costs as Gulfstream. Like Gucci, you pay a lot of money just for the Gulfstream name.

    At the low end of the market, Honda makes a small jet. (This is in the Very Light Jet category which bumps up against the turboprop market).

    At the very high end of the market you get into Boeing Business Jets, and the Airbus equivalent. These are converting airliners to your exact interior design specifications. Airliners are like another order of magnitude higher cost to operate.


  • There’s a class of orbits called “polar orbits” that are sideways and perpendicular to the spin of the earth. These orbits are useful for satellites whose main job is taking pictures of earth, because they will cover nearly all of the earth’s territory over time. You get into a polar orbit by launching to the north outer south.

    Aside from that, nearly all launches go towards the spin of the earth, because it’s a free boost. The fancy rocketry word for this is “prograde”.

    The sun appears to traverse from east to west in the sky. This means that the earth is moving the opposite way: west to east. So if you want to take advantage of the free boost, the rocket needs to take off in an easterly direction.

    The amount of spin you get is greatest if you launch from the tropics near the equator, and it falls off at greater north or south latitudes. In theory, if you set up a launch pad at the north pole, the spin boost would be zero in all directions, because you’re just rotating in place. At the equator, the free boost is around 1000 mph or 1600 km/hr.

    So the ideal launch site is as close to the equator as possible, and it has low population off to its east, in case the rocket blows up or crashes. The United States has two sites that meet these criteria: one in Florida and one in extreme south Texas. Both of these face an ocean to the east. Europe launches Ariane rockets from French Guiana in South America. Russia uses Kazakhstan, which is on the southern ends of the old Soviet Union.



  • mkwt@lemmy.worldtoAsklemmy@lemmy.ml*Permanently Deleted*
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    1 month ago

    There was a book a while back called Guns, Germs, and Steel that delves into this topic.

    The root cause, as I understand it, is that Europe is on a continent oriented east-west instead of north-south. And Europe in particular is on the part of that continent that has a lot of easy access to the sea.

    East-west orientation allows you to transplant plants and animals long distances and keep them at roughly the same latitudes, which means roughly the same climate. That is a big boon for spreading “civilized” agriculture, which is what creates surplus of labor, which creates non food jobs that advance technology.

    Among the common 5-7 domesticated food animals people eat today, all but one or two were domesticated in Mesopotamia, but then spread all over Europe.

    Access to the sea is the other component that turns tech advantage into colonialism, because it gives the transportation. Even today, China and Russia are great powers, but they are forced to be continental powers instead of maritime powers, because nearly all of their coast lines are hemmed in by narrow seas that are easy to blockade.

    There are, of course, a bunch of other factors I’m not even thinking about and competing opinions. But I don’t for one second think that any of this has anything to do with European “innate intelligence” or skin color.




  • I gave you the downvote because I once attended a public lecture by Stephen Hawking, near the very end of his lifetime. It had to be one of the few, very last, public lectures that Dr. Hawking had in him. And the topic of that lecture was the nature of time, and how all of the equations of motion are fully reversible, etc, etc etc.

    Out of all of the topics Dr. Hawking could have discussed, that one is the one he chose. And to me, that means that the nature of time was interesting enough to him to spread around to the public. That there are live issues that are not well settled. And so on.

    Since that time, I’ve not seen any major developments in theoretical physics or philosophy to shift the status quo to an appreciable degree.

    This leads me to the final judgement on your comment: You are wrong. There are live issues to discuss here, and OP deserves to further explain, defend, and debate their philosophy.



  • It matters a lot whether she is a US citizen or not.

    If she’s a citizen, then she can shut up / lawyer up. She has a fifth amendment right to not divulge a phone or computer password, code, pin, or whatever. CBP can detain her for up to several hours, but at the end they have to either charge her or release her into the country.

    If she’s not a citizen, then things are a lot tougher. She still has constitutional rights, including the fifth amendment. But CBP has a lot of leverage, because they can rule her inadmissable. Once that happens once, then it can become really hard to get readmitted later, because this “strike” is on your record.

    The main thing that is tripping up green cats holders at the border currently is old criminal records. That DUI or marijuana or shoplifting charge or conviction from 20 years ago is often not enough dirt to get an LPR deported, but it is enough dirt to deny readmission if they happen to leave voluntarily.


  • If I recall correctly, the photon sphere orbit is unstable, so there may not be a ton of photons there. “Unstable” in this sense means that photons in adjacent orbits tend to diverge away from the photon sphere orbit rather than toward it.

    For Schwarzchild holes, the lowest circular orbit for massive objects is at 3 event horizons, which is above the photon sphere. There are unstable circular orbits down to 2 horizons. Black hole rotation reduces this altitude for prograde orbits asymptotically down to 1 horizon.







  • Exactly. This is completely insane. The DoD has the negotiating leverage to write these right to repair requirements into their RFPs, specifications, and contracts. The idea that their procurement offices simply failed to do this boggles my mind.

    Back in the war, if you had a winning design, you were required to license it, full drawings included, to many different manufacturers at fair prices. The Defense Production Act is still on the books, and it contains a lot of power to control the economy. Why is DoD handcuffing themselves?