"The energy density of batteries is an order of magnitude less than fossil fuels, and you have to carry the heavy batteries with you the entire trip (vs burning off fuel as you fly)."
It's even worse. Nowadays, in order to land, the aircraft needs to be almost empty, otherwise the mechanical structure that supports the stress of impact with the runway may break. So, heavier (as with batteries included) aircraft landing will mean the need to design sturdier landing gear, and stronger landing gear will most likely mean heavier materials as well.
"For jet engines, the only thing that comes to mind is electric aircraft. No single-crystal turbine blades needed at all. I may have picked a bad example, but the principle stands."
I understand the idea you wanted to convey and that commenting on the technical detail is not something we're supposed to do, but the technical side of your example is just too glaring to ignore. A people-carrying aircraft, be it of electric propulsion, or of other type, is heavy. Like, several tons (at minimum) heavy. To acquire the necessary portance, the aircraft has to be accelerated (on its inert wheels) on the runway up to the take-off speed and then to be able to hold the cruising speed, using engines capable of generating such thrust by only moving the air. That's a lot of force right there, and the engine that has to do this, will have to be pretty tough. Regardless of the fact that the source of the on-board energy is electric or not, that same air will have to be moved, somehow, at the needed speeds, and it will be by an engine that will look and work pretty much the same way the current jet engines do, since the shape is dictated by the aerodynamics and the internal design is given by the (air) fluid dynamics it has to work with. The single-crystal turbine blades are just an optimization. Weaker (regular fine-grained casting) materials can be used, but that will mean limiting the performance to lower tolerance levels (and most likely be heavier as well, to compensate for the lower mechanical strength).
Your range checking requirement is just one of many things that may or may not be necessary to someone using this. Taking them all into account (besides the fact that may be unfeasible, if there happen to be some conflicting requirements) would render the solution to be unnecessarily complex. It's better to focus on the minimal set of viable requirements and thus have a base design as simple as possible. For additional requirements, just go and complicate your design (and be the only one having to pay the costs that come out of that complication), hopefully only when and only for as long it makes sense to do so. For the need you mention, some kind of container wrapper may do, with the amount of number's words specified in it. A good thing is that you'd be able to limit the use of such container-wrapped numbers only to some situations (like the exchange of data to and from unsanitized areas).
While there are indeed "details" out there that have a great impact on the macro-dynamic, and even pose as blockers, history also provides us many counter-examples. The steel-making process has been invented and reinvented many times and in different places in an (arguably) independent manner. The same for sea-faring, writing systems, laws, and so on. They have all been different but did enabled progress more or less in similar way, and thus - are also details that it's fair to gloss over.
You two debated this as a philosophical or even moral issue, but it changes everything when you look at it from the natural hazard prospective. It doesn't even have to be a subjective matter. Picture this - you know the climate change is happening and you understand that some colony of animals will surely vanish because of that if you wont do a thing about it. Doing something could mean just taking a few pair of animals and relocate them to a safer area. Do you think that the survival of such descending colony of animals mean anything (to anyone)? Who can argue that it won't be our time (and obligation) to reduce the risk of having the only known capable civilization residing on only one planet or galaxy?
For sure, but that's my point; "taking a few pair of animals and relocate them to a safer area" is not what this paper is discussing. A better parallel would be "take digital photos of the endangered animal and circulate them around the internet." The proposed method doesn't spread us -- it spreads teeny tiny machines we made, for no reason at all other than to say we did it. And long after we're gone, when the Sun has died, far away galaxies will be polluted with little machines, each containing a copy of some data about us.
Right, but it’s only a feasibility study. By definition these only study the minimum system that could accomplish the goal, which was to visit as many galaxies as possible. Given the mass budget and density of the data storage contemplated there’s no reason the probes couldn’t carry enough information to create real human colonies in the process of replicating themselves.
The dilemma of spending significant amount of effort and resources for a colonizing project when the result won't benefit the enterprising society is not new. When looking for a reason, considering only the (individuals' or collective's) benefits on a rational basis does not make much sense indeed. Most likely there must be something more, akin to a religious goal, aiming for species' or civilization's greater good.
It's also called "vision". It's what provides and powers directions on large and long term scales. Those "simple" and "mundane step-by-step issues" are just chores by themselves, yet at the same time may become stepping stones in the context of a well thought vision that people buy into and rally behind.
In the open space, shades get very cold, like a few degrees over absolute zero cold, because even without a medium to facilitate convection and (atmospheric contact) conduction, the loss of heat through mere radiation (into the pitch black universe) is very efficient (for normal, non-reflective materials). Thus, for an astral body to remain in a melted state, continuous steams of energy should be poured in (and some thermo-insulating gaseous atmosphere may also help to reduce cooling, if the body in question would have enough gravity to retain it), but that's hardly a thing to worry for a project where the energy itself is carefully controlled and dosed.
"to Thai, squid, octopus, and cuttlefish are all ปลาหมึก. For English speakers, those are similar things, but all clearly distinct. But for Thai speakers, they're all ปลาหมึก, just different types."
Then, ปลาหมึก = coleoidea? If so, the squid, octopus, and cuttlefish are (in English and many other languages) all just types of coleoidea: https://en.wikipedia.org/wiki/Coleoidea
Coleoidea is a technical word, though, and ปลาหมึก isn't. Ordinary people use ปลาหมึก to refer to all of them, but they might not use that same word to describe e.g. nautiloids. It doesn't map neatly on our technical language.
Also, the kind of satellites that aren't much more than mirrors, even with today's knowledge, they can be designed to change their profile/surface and thus reduce the absorption of the incident radiation, if they'd had to cross the space between the sun and the sunlight collector areas.
It's even worse. Nowadays, in order to land, the aircraft needs to be almost empty, otherwise the mechanical structure that supports the stress of impact with the runway may break. So, heavier (as with batteries included) aircraft landing will mean the need to design sturdier landing gear, and stronger landing gear will most likely mean heavier materials as well.