Suggest you look up the history of currencies in the early United States. You want unstable?

It does it very efficiently.

I believe it does matter. But only time will tell. I have no interest in trying to convince anyone though (well, from time to time it's a bit of fun), I believe these things will become evident. If they don't, I'm wrong and so what?

I did too and never had any problems. I just heard of a few exploits of various things that made me uncomfortable with the idea.

but why would it be lighter than a conventional train?

The main reason is that hyperloop isn't designed to achieve throughput by bundling everyone together into (proportionally) rarely launched trains, but by frequently launching smaller trains fully under computer control - spacing on the order of a few minutes instead of a half hour or so. There's only 28 passengers per pod. That launch rate is easier than many other computer controlled transportation systems, mind you, because there's no intersections - the only thing you could possibly hit is the car in front of you or the car behind you, and only by doing something really ridiculous (it's also more than enough time to stop if something goes wrong, as per the calculations, and the numbers look quite realistic).

but at the least it's going to have to support the tube plus the train cars itself

The tube isn't actually as heavy as you might think. Unfortunately I dont have my numbers on me right now, but it works out to not materially change the picture.

Is it simply that new materials and not having to share tracks with existing trains allow for different, lighter construction?

The real enabling technology for this is high launch rate, and the enabling technology for that is computer control with a simplified control problem (one way, don't hit the car ahead of or behind you). Yes, they'll use modern materials to try to keep things light, but that's not the key factor; the key factor is spreading out the load. It also adds a great deal of convenience for passengers - near constant departures and quick to get in and out of. The proposal really has more in common with a roller coaster ride than with a train: frequent small cars, quick loading and unloading, computer control maintaining spacing, etc.

But I'm concerned that it might be too optimistic

In the beginning I did too. But I've read the proposal and cross-referenced the numbers, and I'm sold. The cost figure is totally different from rail because it's really nothing like rail. For example, the track construction is far more like pipeline construction (really, it *is* a pipeline construction), so you need to compare to pipeline construction costs, not track construction costs. And it actually favors comparably with most types of pipeline, like oil pipeline, which are bogged down in environmental regulations and almost always lots of lawsuits, plus face high construction costs from having to generally go through wilderness areas, and a ton of other things. In most aspects oil pipelines have a far tougher time of it; the only thing that Hyperloop has harder is establishing and maintaining tolerances (but they have some very good proposed solutions for achieving the them quickly and affordably).

You don't even have to typo. There's a nasty bug in Konsole where if you're typing under load, it will get characters out of order. So rm -rf /var/tmp/x /var/tmp/y becomes rm -rf /var /tmp/x/var/tmp/y (or something like that). That was fun to recover from.

Cool. I've been thinking about looking at Glacier as an additional backup option. Really needs to be supplemental to backups under local control as well unless it's just stuff you really don't care about too much.

You have to have a realistic estimation of the value of your data.

In truth, for many of us, the most valuable data is the most trivial to back up.

He didn't protect himself against malicious code and got caught by incompetent code.

Yep. If you don't have offline backups, you're going to have a bad time.

That is a different permission system to the one under discussion.

What's the deal with NVidia and on-board graphics? Have they exited the market? I recently had to replace a MB with onboard NVidia and wanted to find another with NVidia onboard (because drivers) but nada. Fortunately the drivers for the Athlon with onboard ATI were not hard to install and it works fine for what it's used for but it was just surprising and perhaps what was even more surprising was the lack of commentary. Like they just went out with a whimper.

But since Musk intends to use the I-5 median on the long straight San Joaquin stretch, why will he use columns that entire distance?

I'm not sure what you're not understanding here. You have two seven-foot diameter pipes here, where are you picturing they should go if not "up"? I doubt anyone would approve of you eating up the entire median the whole way, if they'd even fit to begin with. If you're thinking about expanding the road, that takes land acquisition and all sorts of added hassle. Also, as straight and flat as the road seems to you, it's not so straight and flat to someone moving at 740 miles per hour. The columns vary in height and how they hold the pipe to compensate for the irregularities in the landscape.

And given that he will be using columns to save cost in urban areas, why not come right imto the city? Bringing it to the vicinity of Union Station would be a powerful selling point.

I do find that a valid criticism, something that one may well pass off to thinking in terms of airports - ignoring that airports are positioned on the outskirts of cities because they *have to be*, not because that's a good thing. That said, I'm sure the people permitting any actual implementation would pretty much force them to go into town - especially if they're also begging for funding. The highways get a bit twisty in town but there's some nice straight railways they could go over on both ends.

True. Although to be fair oil pipelines often have to be built in places where the ground is terrible - for example, permafrost, bogs, etc, vs. the median of an already-built highway.

Hyperloop does have deflection calculations worked into the proposal. The uniformity of the interior surface proposed to be accomplished by mounting a rotating buffing disk to a pipe-crawling robot (like those already in use for sewer and water pipe maintenance), having it grind and polish out the welds and any irregularities in the steel as it goes. Since pipe-crawling robots are on the market today, I don't see this as a serious hurdle. Certainly way cheaper to accomplish then fighting protracted legal battles over environmental regulations ;)

Either way, the people saying that Hyperloop should cost many dozens or hundreds of billions of dollars are clearly out of the ballpark. That's just not what long elevated steel pipes and associated hardware cost.

Hmm, another thought: if instead of air you maintained a sparse methane atmosphere, you could get a 140% the speed you could in air. More challenging to maintain such an environment, of course, since leaks into the pipeline would be air (unless the pipeline was surrounded by a thin methane sheath). At least it wouldn't be flammable - at such low partial pressures, there's no amount of air that could leak in that would lead to a flammable mixture.

Ammonia has similar performance to methane, but it's corrosive, so methane would probably be a better choice than ammonia. Neon also has similar performance to methane, but is way more expensive.

For the excellent performers, helium has a speed of sound 3x higher than air, and hydrogen 4x higher. But helium is rare and increasingly expensive, while hydrogen embrittles steel, leaks through almost anything, and leaks into the atmosphere have adverse consequences to the ozone layer. So I imagine both of those options are out.

If one scrubbed oxygen from the pipeline, with any sort of easily-oxidized material placed regularly in the pipeline, you should be able to get a couple percent boost in max speed, nitrogen has a slightly higher speed of sound than oxygen. But whether that would be worth it, probably not, unless the oxygen is problematic in other ways.

All of that said, I think the best option would be water vapor; at such low pressures, any water in the tube will automatically vaporize. Such a low partial pressure should pose no rust risk (that's actually very dry!), it's cheap, and most importantly, your vacuum pumps can simply discharge it and you can just feed more into the pipeline as needed, there's no need to filter it out or neutralize it first or anything. The more you approach a 100% water vapor atmosphere, the more you approach having 150% the max speed that air would give you. Instead of the 1190 kph/740 mph that the current Hyperloop design tops out at, you could potentially go upwards of 1790 kph/1110 mph. The downside is of course the increased pumping effort to try to keep the atmosphere as close to 100% water vapor.

If one could achieve a practical average 1000mph then that's 2 1/2 to 3 hours New York to Los Angeles, depending on how straight the line would be. For an express that stayed in the countryside, that is; each stop along the way would cost time. Hopefully the system would be smart enough to let passengers bundle together into "express" pods and let them bypass stations they don't want to stop at (although the lower in-town speeds would still be a hindrance)