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How Bird Flocks Resemble Liquid Helium 6

Posted by timothy
from the beats-speed-of-sound dept.
sciencehabit (1205606) writes "A flock of starlings flies as one, a spectacular display in which each bird flits about as if in a well-choreographed dance. Everyone seems to know exactly when and where to turn. Now, for the first time, researchers have measured how that knowledge moves through the flock—a behavior that mirrors certain quantum phenomena of liquid helium. Some of the more interesting findings: Tracking data showed that the message for a flock to turn started from a handful of birds and swept through the flock at a constant speed between 20 and 40 meters per second. That means that for a group of 400 birds, it takes just a little more than a half-second for the whole flock to turn."

Comment: Most alt.coins are designed to be ASIC-hostile (Score 1) 188

For Bitcoin, ASIC is the only way to go, but most of the interesting alternative coins are designed to be hard or impossible to build ASIC miners for. (They're also designed to be GPU-miner-hostile, but some of those have been worked around.) One of the tradeoffs with that is that CPU-only mining is botnet-friendly; it's harder to abuse botnet machines' GPUs (especially in cloud servers or routers that don't have GPUs.)

I avoid the whole problem by mining Dogecoin; it's close enough to no value that it's seldom worth stealing (though there was a botnet in the news recently that actually got $200K from mining it.)

Comment: Re: Yeah, 2 ports + WiFi - so? (Score 1) 46

by billstewart (#47547717) Attached to: A Router-Based Dev Board That Isn't a Router

No, generally a router has an inside and an outside, and sometimes a third port as a DMZ; you're thinking of a router with an ethernet hub attached, like many home routers. There are routers with more routed ports, and there are one-armed routers also, though that's less likely to be useful.

Comment: Price is reasonable - $35, not $90 (Score 1) 46

by billstewart (#47547711) Attached to: A Router-Based Dev Board That Isn't a Router

It's $35 plus shipping for the development board with the module soldered on it, so it's about the same as an Arduino; the $89 price was for two of them plus accessories like cables and power supplies. They're asking for not very much money to finish their software development, and the real question is whether their software is any good.

Comment: Difference is the route, not the protocol (Score 2) 362

The reason the VPN connection went fast isn't that EEEVILLL Verizon was throttling the customer's Netflix connections by doing deep packet routing and didn't do that to the VPN. The pipes Netflix bought to deliver movies to their paying customers who use Verizon weren't big enough to carry all the demand, at least at the peering* point that customer's traffic went through, while the pipes they bought or peering they got for free were big enough to reach the VPN endpoint, and the VPN endpoint had bought enough bandwidth from their ISPs to get from there to their peering point with Verizon, so there was enough bandwidth on the whole route to carry the movie that way.

That's not to say that there aren't ISPs harassing particular content (there was at least one well-publicized case a few years ago of some telco ISP blocking VOIP, and of course most of the cable modem and some DSL providers block home web servers), but this ain't one of them.

(*Peering unfortunately means two different things here - it's giving each other service for free, and it's having BGP-managed interconnections, usually at the big internet exchange locations, to pass traffic, not necessarily for free.)

Comment: VZ isn't capping the customer's broadband. (Score 1) 362

The problem isn't from Verizon's backbone to the customer - otherwise the VPN connection would have also been slow. It's the pipes from Netflix and their peering/transit providers to Verizon, which aren't big enough to handle all the Netflix customers on Verizon, at least in that region.

Also, what do you mean "has to set aside 8tb for sync"? Do you mean the ISP has to provide 8TB of some kind of storage hardware, or 8 terabits per second of traffic from somewhere to somewhere else? That's fairly huge, considering that most data connections aren't much bigger than 10 Gbps per wavelength (some carriers use 40, but it's not usually price-competitive.)

Comment: Mod Parent Up Please - It's exactly right. (Score 1) 362

Netflix either buys bandwidth or convinces ISPs to give it to them for free as peering. Its peers / transit providers are either big enough to peer with Verizon for free, or buy bandwidth from Verizon, and they don't have fat enough connections to Verizon to carry all of Netflix's traffic to this customer, at least at the peering point that Netflix's traffic uses to reach that customer (Netflix may have enough bandwidth to reach VZ customers in the other part of the country, e.g. LA peering is full while Seattle or DC isn't.)

The customer's VPN provider may very well provide free/cheap connectivity to Netflix (or at least fast enough), maybe even one of the providers Netflix buys from, because they're cheap. And they may also get it from somebody who has good bandwidth to Verizon. But peering's just peering - it's not transit.

Comment: Advanced Placement Tests aren't very representativ (Score 1) 117

by billstewart (#47539913) Attached to: AP Computer Science Test Takers Up 8,000; Pass Rate Down 6.8%

(First of all, to reply to the parent article, the test isn't for people graduating from college, it's for people in high school who will get to use the results to place out of courses in college. In my case that meant I could start more advanced calculus classes a year early, which was really useful, and got some extra credits for biology that didn't affect anything but probably looked good, and if I'd been at a college where tuition prices were by the course instead of the semester, it would have probably saved me some money.)

So it's nice that 39,000 students had enough high-level CS courses in high school that they were able to take the test, but that's a pretty small fraction of the number of kids entering college, even just in the STEM fields, and it's also limited to those high schools that had a good enough CS program to make it worth taking the test, so the statistics are probably not all that representative*.

(*And the fact that I misspelled "representative" in the title doesn't mean I'm bad at English; I ran out of characters in the title box. :-)

Comment: Most of Cal's water is for farms, not homes (Score 1) 367

by billstewart (#47529071) Attached to: Western US States Using Up Ground Water At an Alarming Rate

Residential rates matter a bit if you're trying to get people to install low-flow toilets or drought-tolerant non-grass landscaping, but if you live near the Niagara river, you can afford a lot more land than almost anybody in LA (except the folks on unstable hilltops.)

But that's not where California's water goes. 80% is for agriculture, and about half of that is for feeding cattle. It's at subsidized prices one or two orders of magnitude cheaper than residential water. There's also a good chunk of it going to industry.

Comment: Lawns, Veggies, other ground cover (Score 1) 367

by billstewart (#47529057) Attached to: Western US States Using Up Ground Water At an Alarming Rate

Most vegetables are seasonal, not perennials, and in most climates you'd want year-round ground cover. It's ok if that's grasses that go dormant in the summer or winter, as long as they still prevent erosion and mud, but growing zucchini not only won't do the job, but you won't be able to find enough grocery bags to leave it all on your neighbors' doorsteps. Most of the SF Bay Area isn't quite right for desert-style xeroscaping (even though prickly pear cactus grows really well here), but there's a lot of low-water native vegetation that does ok.

HOAs would have a fit. But boomers were the hippie generation - we approved of healthy food, organically grown veggies, all that stuff. (As long as somebody else does the hard work :-) In my case, I don't have ground-level dirt of my own, just pots on a balcony, and the squirrels have already stolen both tomatoes, but I liked doing extensive gardening back when I had a yard. And with a yard full of zucchini, I wouldn't have to tell you kids to get off my lawn.

Comment: Evil TOR Conspiracy or OverConservative Lawyers? (Score 2) 51

Given what the actual authors of TOR have said about their system over the years, the likelihood that the talk was cancelled because they've suddenly become evil (or have suddenly revealed that they've been evil all along!) vs. the likelihood that it was cancelled because the lawyers at CMU were being overly conservative and paranoid, I'll go for the latter explanation. There are projects for which that wouldn't be the case.

TOR has its limitations and weaknesses, and the developers have always tried to be upfront and public about them, both for the threat model / design and for the code itself.

"Just think of a computer as hardware you can program." -- Nigel de la Tierre