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Comment Re:I don't even know what "hyperloop" is any more. (Score 1) 216

In addition to what bws111 wrote:

Re: the MIT capsule: it's nothing like the Hyperloop Alpha concept (hence my post). SpaceX's test track that they're building is designed to handle a wide variety of vehicles, not just the one laid out in the Hyperloop Alpha concept. IMHO the MIT concept is utterly uninspiring. The drag levels are vastly higher, which are going to ruin pretty much every appealing aspect of the concept.

(but no, the tube has no electromagnets, the MIT design involves induced magnetic fields for propulsion)

Comment Re: No problem (Score 1) 537

No it isn't. Absolutely nothing stops ad blockers using heuristics to identify "ad shaped images" or simply having manually written lists of DOM paths to nuke.

I find this whole attitude of "shut up whiners, make your ads EXACTLY meet my unique criteria or else I'll just benefit from your work for free - see if you can stop my nya nya" to be appalling.

Apparently people haven't thought through where this ends. It ends with someone eventually making a non-web content platform that doesn't support ad killers, uses video-game like "anti cheat" techniques and which gets the lions share of the best content because publishers are sick of being ripped off. You know, kind of like how the PC used to be the primary gaming platform in the world and eventually most of the AAA games were coming out on consoles first, and PC maybe or never. Basically, because of piracy and the console makers commitment to fighting it.

Comment Re:Things that I wish wouldn't keep getting repeat (Score 5, Informative) 298

It takes billions (not millions) of years for hydrogen atoms to fuse in the sun - that is precisely why the sun has a billions-of-years lifetime. So in building a fusion reactor, we need many orders of magnitude higher reaction rates, and to achieve them at many orders of magnitude lower densities. One way of doing this is to have much higher temperatures. The solar core temperature is about 15 million degrees and TFA has 50 million degrees for this new result, and 80 million degrees for half a second at a European reactor. This sounds unimpressive, but the reaction rates are very sensitive to temperature - proportional to about T^8 as I recall, but I didn't quickly find an online reference for this. 75 million degrees would therefore give a boost of about 5^8 which is about 400,000.

In the sun, the first reaction in the chain (proton+proton->deuterium) is the rate limiting step. In a reactor, we can provide deuterium enriched fuel and bypass this step. I don't know what the reaction rates are, but I suspect that this will be a greater benefit that the higher temperatures. You can do even better with tritium in the fuel, but your reactor becomes an intense neutron source, leading to induced radioactivity in nearby materials. Some proposed designs use these neutrons to breed more tritium from a lithium blanket around the reactor. (Once I get beyond the proton-proton chain reaction, I'm just relying on pop-science knowledge, so corrections from the more knowledgeable are welcome.)

Stars a bit more massive than the sun burn hydrogen via the CNO cycle, which has even higher temperature dependence (from memory, about T^17). I've never heard of anyone suggesting using the CNO cycle in a fusion reactor - presumably there are good reasons, but I don't know what they are. One problem is you need to wait for radioactive decays, but these have half-lives on the order of 1 to 2 minutes, and a commercial reactor would be running for much longer than that.

Comment Re:I don't even know what "hyperloop" is any more. (Score 1) 216

Indeed. That's one of the few things that one can say has nothing to do with either the original Hyperloop alpha concept or the new college competition entries. Pneumatic tubes mean that they make use of pressure to push things - that's what the word "pneumatic" means. Pressure being the one thing Hyperloop (all permutations) distinctly lacks.

Comment Dated info. (Score 1, Informative) 17

Comment I don't even know what "hyperloop" is any more. (Score 1) 216

Seriously. I was a big fan of Hyperloop Alpha. But the MIT team that won the "Hyperloop" contest is proposing something nothing like Hyperloop. The test track that SpaceX is building is designed to support a wide range of vehicles, most nothing like that in the Hyperloop Alpha document. So if I say "I like hyperloop", I don't know what exactly it is I'm supporting anymore. What exactly is "Hyperloop" these days?

All I can say is that I really liked the alpha one. The MIT team's maglev thing is Meh^2.

Comment Re:The fun (Score 1) 216

If you're dedicated enough to climb onto a well elevated tube, cut a hole large enough to pour concrete in through inch-thick steel - after sabotaging all of the pressure sensors tbrough the whole length of the tube and feeding them false data - and then using a concrete pump with a very tall boom fill in the tube with concrete, in order to kill people.... then why not just fly planes into skyscrapers like most people? I mean, if you're going to go through that much work.
 

Comment Re:Roll-back as in play-back? (Score 2) 69

Banks can roll back transactions for various reasons, e.g. bankruptcy proceedings, mistakes by their own operators or by customers, or ... transactions that are fraudulent. The Metel gang obviously had a sense of irony in exploiting this ability to undo fraudulent transactions to their own benefit.

Comment Re:I can understand small first batches (Score 2) 109

Since you have experience... I've often had interest in physical computing, but have never gotten around to learning / messing around with it. What would you find to be a good "introductory" system (for someone with lots of programming experience but only grade-school/100-in-1-electronics-kit/basic soldering/etc level electronics experience) for the purposes of, say, controlling steppers, variable-RPM drive motors, taking voltage readings, etc?

Comment Re:Kessler, anyone? (Score 1) 42

Of course they're taking business from other players - but that's not the question. The question is if they're making new business that otherwise wouldn't be there. Thusfar, I haven't seen anything to suggest that.

But, the potential is there in the future if they can keep bringing down costs, as they're hoping.

And IMHO, we're not even remotely near the point where space junk is going to stop us from launching things into space. Not even close. Particularly in LEO where orbits decay relatively quickly. It's always a threat, a threat that rises with the launch rate, but as far as being prohibitive... no. And there's some good evidence that things are moving in a positive direction - increasingly, nations are passing laws mandating that satellites be moved to disposal or graveyard orbits at the end of their service life, rather than just leaving them out there as potential collision/debris generation hazards.

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