A drop of water can self-form into a sphere by surface tension alone. If that is dropped off in space, it becomes a planet??

Not in my view. That isn't implied by what I said, either. I said mass, and I meant mass. If you dropped your putative drop of water off in space, by the way, by which I mean in a vacuum, I don't think it would be able to hold itself together by any means. I suspect it'd most likely sublimate before you even had a chance to really get into admiring it.

Oh, by the way, our sun orbits the galaxy, does that mean we aren't a planet here on earth because we orbit around something that has its own orbit?

Not to me. Again, I said nothing of the sort, and I implied nothing of the sort.

If not, then why do moons get to be moons when many of them are bigger than the "planet" Pluto, when they orbit around something that has its own orbit around another body?

Moons get to be moons in the context of a solar system; once you step beyond that level of organization, most of us (apparently not you, but that's ok) use different terminology to indicate groupings of stars, gas clouds, supergroupings, and so on.

But hey, don't let me get in the way of your irrational ranting; you've got a good head of steam going there, be a shame to see it peter out too soon.

We see articles about how few people are scientifically literate, and so many on Slashdot decry "We are geeks, we understand science!"

Appearently, nope!

Actually, my dear fellow poster, it is you that does not understand science. Science is a method. Information gathered and suppositions constructed are both data. Such data, particularly when the scientific method is applied, may give rise to (hopefully) more accurate metaphor(s) (more data) as to how nature behaves, and that in turn may let us go a little (or a lot) deeper next time around. Science is a very simple, and beautiful, method.

Back to data. Data is subject to naming, among other things, and those names are (a) abstracts selected for the convenience of the various users, (b) significantly arbitrary, (c) quite often of a dual or more diverse nature (and still 100% correct), for instance "daisy" and "bellis perennis" and "flower" and "that thing that makes me sneeze" and (d) often extend into the metaphorical and allegorical realms in order to further-, and/or better-, and/or simply re-define the issue(s) at hand. This most definitely includes one's own personal or sharable naming conventions and specifics.

When something is controversial or simply not static, we will often see the naming structure(s) and/or system(s) undergo permutation, mutation or even outright replacement. Brontosaurus, apatosaurus, brontosaurids, etc. Those are good examples of names that changed for some pretty good reasons (wrong head on the body... the "brontosaur" was an apatosaurus that mistakenly got a camarasaurus head on it, lol. Now "brontosaurids" means, hand-wavingly, "those long-necked ones" and not much else.) These nomenclature mutations are part of the process of integrating the data into our best-approximation of knowledge about the world, which, coming back around to square one, is not "science" either. Science is a method that we "do." Knowledge is not science itself, although it can and should be used in the undertaking of science.

Further, as the users of the data, objects, information vary, often so goes the terminology. Programmer: "Time for za!" Secretary sent to get it: "Can I order a pizza, please?" counter person: "pie, cheese" artisian: "yet another culinary masterpiece!"... they're all correct. It's not a problem. It's normal and natural. It is still normal and natural if someone in a particular household begins to call pizza "magic goo"... and who knows, it could be what everyone calls it some years down the road. I still kind of twitch when someone says "you suck", because when I was a teenager, that was a deadly insult, worthy of an immediate fistfight. Means something quite a bit more casual today, something absolutely unrelated to its original meaning. And so it goes. Naming is by its very nature a malleable domain. As it should be.

The bottom line here is, just because a few astronomers (and it was very few, btw) voted for a particular usage, does not mean we have to, or even should, comply if we don't agree. I'm sorry if that seems too chaotic for you, but that's really the way it is, and likely always will be, too.

But to decry that because you learned something one way, therefore that convinces you forever, that's just plain stupid.

Well, good thing I wasn't doing that then, eh?

Cheers! :)

A protostar, given it's in a seriously pre-fusion state, will (as far as I know) be large enough to have quite decisively pulled itself into a spheroid. If it is orbiting another star, I'd say that at that point, it is a planet and a protostar.

As I see it, protostars seem to refer to a class of planet, just as do gas giants, balls of frozen gasses, molten worlds, rocky, airless worlds, and earthlike worlds. That namespace is a very rich field to till, I think.

Once it lights off, I see it as a sibling (binary, trinary, etc.) by virtue of being stars in thrall to one another's gravity. The star with the greater mass I'd call the primary, the next most mass the secondary, etc.

If it is just sitting out in space by itself, I'd designate it a (rogue) planet and a protostar.

Sure, planets can radiate all kinds of things, for all kinds of reasons. Aurorae, ionizing radiation, IR, UV (some high energy electrical storms do this here), atmosphere, monkeys in tin cans... :) ok, that's pushing the indirection a little hard, but... lol

At this point, I'd say that anything that had lit its fusion lamp gets the designator, quite possibly qualified, of "star." There are various kinds of post-fusion states; neutron stars, black holes, perhaps even just dead cinders and fragments, and of course gassy / radiative remnants resulting from their destruction. Probably lots of other things too. The world, Horatio... etc.

That's all just my own outlook though.

I don't see why, when another planet is discovered, we can't admit it.

So... "the problem"... doesn't strike me as a problem.

I don't know -- I think it's about 13 right now? Could be more or less.

Why?

Just to be explicit, I wasn't complaining about the number nine. Just the very weird and arbitrary demotion of pluto from planetary status. Which I do not go along with.

I like a nice, sane, consistent definition. :)

Covered it. Read my post again.

And how do we know that the real benefit doesn't come from hitting yourself with birch branches?

zblockquote>See: Cabin_Pressurization [wikipedia.org]

A person needs at least 20kPa *from the mask to breathe*. Not 20kPa *ambient pressure*. Please learn to read.

The "problematic loading on the capsules" is from the high speed aerodynamics, not the ambient pressure

Aerodynamic loading = pressure. If you have high loadings, you have high pressures. Period.

Are you talking about what I was talking about? I was talking about an electric motor, not a fuel-driven one.

What sort of claim is that? Since when do oxygen masks need 20kPa to function? And secondly, if there's "problematic loading on the capsules" from too much pressure on the pressure-compromised capsule, then your pressure is also way too high inside. Which means that you've repressurized the tube way too much. So the solution is: Don't do that!

Branching at full speed is probably not possible with the Hyperloop as designed; the skis are curved to match the diameter of the tube, with a ~1mm clearance with the tube surface, so there is no passive tube design that could accommodate a "switch". In order to continue from Section A to either Section B or Section C, you'd have to make an intermediate length of tube several hundred meters long that could be physically moved at one end from B to C, with sub-millimeter precision

Wait, meaning that while it's technically possible, but it'd be really tricky to accomplish? Gee, I wish I had written something like "Branching would be really tricky, but there's no physical barriers" at the top of my post ;)

The reason is threefold: drag continues to increase at higher speeds regardless of the speed of sound

Drag is reduced in the first place by using hydrogen even at a given pressure. And you can use 1/4th the pressure and still maintain lift because you're moving four times as fast. And given how few reboosts are needed from LA to SF in the base case, a few more per unit distance hardly seems limiting.

If you consider that the steel Hyperloop pipe draped across 30m-spaced pylons will approximate a vertical sine wave, then at 700mph the allowable sag is only about 5cm

Irrelevant because earthquakes impose far more deflection that you have to be able to counter (and that the proposal calls for countering) than a craft moving past.

Mechanical braking from 1500mph in the event of an emergency is also a non-starter

What, you're picturing drum brakes or something? You're moving at high speeds in a giant steel tube. Magnetic braking couldn't possibly be easier.

a 700mph capsule will incur about 2g's of aerobraking deceleration

Where are you getting this from? Even if the tube was instantly full pressure (which it wouldn't be), a streamlined shape will not experience 2Gs at 700mph, any more than a passenger jet losing full engine power does. And anyway, 10g horizontal is not fatal even if that was the case. The average untrained individual, properly restrained, can tolerate 10g for a minute without even loss of cognitive function.

Not only that, but if your craft is travelling four times as fast, you're sweeping through four times as much gas per unit time to compress under the skis.

Hydrogen has all sorts of advantages. And the very low pressures prevent most of the negatives. The only one that I don't know about and would require testing would be what sort of reaction would one see as a craft moves past, with any residual oxygen. If I had to guess, I'd guess that you will get some combustion, but the craft moves past so fast and the mixture will decompress so fast, I would think the rate would be quite limited.

First off, if servicing that requires full de/repressurization is some sort of frequent event, then the whole concept is doomed for reasons entirely unrelated to anything in this discussion. Secondly, 1/5 ton of hydrogen at industrial rates is about $200. Whoop-di-doodle-doo. And the advantage is being able to travel at mach freaking 4, not about the reduction of drag at a given speed (which is, FYI, true also).

As someone else already mentioned, it uses low pressure air because the "trains" are ground-effect aircraft, not maglev. They need air.

Secondly, the pumping budget to overcome leaks is so small, both in terms of capital and ongoing costs, that you could increase them by an order of magnitude and not have any sort of practical effect on the budget. Whatever factor you increase over the baseline increases the factor you can replace air by. You don't need 100%.