Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. ×

Comment Re: Rockets are too expensive (Score 1) 308

Note your launch cost analysis is not useful: the entire ribbon doesn't need to be put into space. The best and cheapest way to build the elevator is with a seed string.

My launch cost numbers were to LEO - GEO is a lot more expensive - and so was only ever intended as a ballpark figure. The seed string itself needs to be lifted and I'd be very surprised if you could do that for under a billion. Sufficient strength of carbon nanotubes to be self supporting (based on theoretical models - we still can't actually build them) would come in above that for launch costs.

Comment Re:Rockets are too expensive (Score 1) 308

Cotton is strong because the individual threads are imperfect and so the strength comes from the friction between the fibres. Current nanotubes have almost no friction between the fibres, so when you spin them together you end up with something that simply falls apart when you pull on one end. There are research projects to try to improve this, but claiming that it's no different from cotton or wool implies a complete failure to understand the problems.

Comment Re: Rockets are too expensive (Score 2) 308

How much would it cost to make 50 thousand miles of 3-foot, paper-thin steel?

Assuming 'paper-thin' means 1mm thick, then that's around 75,000m^3 of steel, or about 680 Gg. At current steel prices, that's about $250-600m, depending on the kind of steel. The cost of getting that amount of steel to LEO (vastly cheaper than GEO, but assume that most of the mass doesn't have to go up to GEO) at current prices (assuming the cheapest possible launch) is just under $4tn.

The real question is why you care, because steel doesn't have anything like the tensile strength required to be a tether.

Comment Re: Maybe, but maybe not (Score 1) 299

My memory is that if Amazon had been happy with just books and bookish stuff they would've turned a profit much sooner. A smaller, and possibly short lived, profit...but sooner.

Profit is a pretty misleading metric. Amazon had enough income to exceed their operating expenses for quite a while. This is the intuitive definition of profit, but not what appears on a balance sheet. They were taking all of that money, using it as collateral to borrow more, and then investing all of that in growing their business. That meant that they didn't make a profit, but only because anything that would have been profit was ploughed straight back into the business. They were also very willing to shift markets. They created a cloud offering because they had to over-provision in their data centres to cope with spikes in demand and realised that they could sell some of this excess capacity. This turned out to be so lucrative that they poured all of the profits from their retail arm into expanding it for years. They did the same thing with the Kindle.

Comment Re:Sounds good to me (Score 5, Informative) 299

For the employer it's a win, but for consumers and staff it's not always

It actually isn't. There was a Freakonomics episode about this a few months ago. The problem is that front-of-house staff in the USA are now getting a significant proportion of their income from tips, which are a percentage of the total cost. This means that their income has gone up a lot more over the past couple of decades than that of kitchen staff, to the point where someone with a cooking qualification can still make more money waiting tables than being a chef. Even worse, it means that the income varies hugely between days, so it's trivial to find someone to work on a Friday or Saturday night, because they'll make loads of money, but restaurants often can't find people to work on Wednesday or Thursdays, because they'll make a lot less (for regular slots, you can establish a rota, but if you need cover for a sick employee then it's much harder).

Comment Re: Bloggers (Score 4, Insightful) 299

There are a few things that make Uber better than a taxi company, from a customer's perspective:
  • They tell you up-front how much it will cost.
  • They handle the payment automatically.
  • They aren't geographically limited, so you can use the same app all over the world, not have to try to work out which taxi company is reputable when you're travelling.
  • Start and end points are put on the map by the customer, so there's never a 'oh, I thought you meant the other Foobar Road' issue (I've hit this in Boston, where you have several overlapping cities that have many of the same street names, so you start heading in one direction before realising that the driver thought you meant somewhere else).

The problem for Uber is that there's absolutely nothing stopping the taxi companies adopting all of these. Many will already do fixed-price trips. If you have a corporate account, they'll happily just bill the company rather than the rider. An open protocol for interfacing with their dispatcher system and allowing them to provide locations of taxis that could be dispatched and quotes would let a federated system work. Some individual taxi companies already have apps that let you provide GPS start and endpoints.

Comment Re:That's a new war (Score 2) 88

You don't even have to make it public, you can make it privately owned by the person or people at the end of that mile. A few places have followed this kind of model and had the connection to the nearest back-haul link owned as part of the title on the individual houses and that include a share in the ownership of the company that owns the exchange and contracts maintenance and service provision to other ISPs. It puts the individual homeowners in a much stronger bargaining position because now an ISP that offers competitive rates and service gets a few hundred customers and loses them all at once if they provide bad service.

Comment Re:"Police found Purinton 80 miles away at Applebe (Score 1) 1081

I know I know, "clump of cells" and all. But Progressive are incredibly blasé about life in one sense and incredibly dramatic about it in another.

There are strict legal limits on abortion, which basically boil down to 'you can't kill it if it has a brain stem'. Do you eat meat? If so, the animals that you kill are closer to an intelligent being than anything that it's legal to abort. The millions sperm that die every time that you ejaculate are also denied the ability to grow into an adult human, but you don't seem too concerned about those, yet that have precisely the same level of intelligence as an aborted zygote and each one has half of the ability to grow into an adult human. Attempting to claim some kind of moral equivalence between a collection of insentient cells and a living sentient human is insulting to anyone reading your post.

Comment Re:"Police found Purinton 80 miles away at Applebe (Score 1) 1081

Please tell me how you plan to get rid of them in such a way that disarms criminals equally as well as it disarms law-abiding citizens

You might like to look at the UK, where owning a pistol went from something anyone might do for self defence, to something that you'd only do if you were a member of a shooting club, to something that you basically can't do, over a period of a few decades. One of the ways that this happened was by significantly increasing the penalties around the '60s for crimes where the perpetrator was armed, as well as for illegal trafficking in firearms. If carrying a gun to a crime means that, if you get caught, you'll spent 20 years in prison instead of two, then a lot of criminals will take a knife instead. If a firearm-related murder with an illegal gun leads to the seller going to prison for almost as long as the perpetrator then black marketeers find something lower risk to sell.

Comment Re:You don't own common sense (Score 1) 1081

It's important not to forget the people who would have died if they didn't have a gun to defend themselves, even if your coworker would have had a better chance if guns were banned.

I think the Rochdale Herald said it best: Bad guys with guns get more practice complain good guys with guns

Comment Re: Why is Amazon/Alexa even saving recordings? (Score 1) 116

Not quite true. The hardware detects a simple sequence of phonemes that might be Alexa. It then wakes up some software to try to parse the word. The data might still be shipped off to the cloud service for spurious wakeups. Names like Siri and Alexa are intentionally designed to have sequences of phonemes that don't appear commonly in English to minimise this.

Comment Re: Why is Amazon/Alexa even saving recordings? (Score 2) 116

I don't particularly worry about Amazon intentionally violating privacy with Alexa, but when you have something like that it's a wonderful target. The mute button is entirely software, so there are all sorts of things that an attacker can do if they compromise either an individual machine or the Amazon software update server. For example, it would be a trivial patch to make it stream the audio to a different cloud service when you press the mute button. Those thousands of people working at Amazon on Alexa also make it relatively easy to sneak someone into the company to exfiltrate user data. Even if their software is entirely bug-free, what happens when someone manages to do a dump of everything that Alexa has learned about a few million users?

Slashdot Top Deals

The trouble with money is it costs too much!