Beta
×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Comments

top

Do Dark Matter and Dark Energy Cast Doubt On the Big Bang?

Alef Re:Oh good lord. (225 comments)

"Use" means to convert it to a different form

...and to extract work while doing so. No? Which means converting it to some form where it has higher entropy.

Look, it seems like you are more or less just making stuff up based on your rather incomplete understanding of thermodynamics, which is why recommended you to actually read up on the subject. Setting aside the rather dubious claim that a perfectly isolated system can even exist, what you are describing is exactly how you could define a perpetual motion machine of the second kind: an isolated system that performs work using energy from a single heat reservoir, without transferring heat to an external cooler reservoir. Such a machine cannot exist, because it violates the second law of thermodynamics, which states that the entropy of an isolated(!) system never decreases. The system tends towards thermal equilibrium, where all the energy is converted to a uniform distribution of heat.

If you had bothered to look any of this up, you would have already known this, instead of speaking out of your ass based on what you think a perpetual motion machine is and why it must be impossible.

The key flaw in your reasoning is that you seem to think of energy as something that's equivalent regardless of its form. It is not so. In fact, whenever we use energy to perform some work, it actually isn't the energy in itself that we are using, but its state of being far from equilibrium. Its "order", for the lack of a better word. The energy is just a carrier. And when we are using heat energy, we are actually not using the heat in itself, but exploiting the temperature differential between the heat reservoir and a cooler reservoir. That's why all heat producing power plants need cooling water, and the reason jet engines get higher efficiency when flown through cooler air at high altitude (even if it's thinner). Conversely, it explains why a refrigerator requires external energy even though it is removing energy from its interior, and why a heat pump can have more than 100% heating efficiency whereas distributed heating can never reach 100%.

One physicist who have written a lot about these things is Ilya Prigogine, if you are interested to read more, although I'm sure you could find many others.

about two weeks ago
top

Do Dark Matter and Dark Energy Cast Doubt On the Big Bang?

Alef Re:Oh good lord. (225 comments)

I think you should ask yourself what it actually means to "use" energy. What purpose can energy have that does not involve irreversibly transforming it to heat?

Or to put it another way: If you have a system that takes in a lot of useful energy, and it does not transform this energy to heat (which inevitably would be radiated as black-body radiation as the system's temperature increases), then you are either: 1) wasting energy, by not exploiting all the work it could have performed before releasing it, or 2) just storing it without actually using it (although the process of storing it would involve performing some work as well).

If, on the other hand, you have managed to build a magical system that can perform useful work without extracting it from the energy you are continually collecting, but can "reuse" energy like a perpetual motion machine, then why the fsck are you collecting more? You don't need it!

Honestly, though, I really think you should pick up a physics text book that covers thermodynamics if you want to understand these things. From your responses (assuming you're not just trolling) it's evident that if you ever read one, you either didn't understand it, or you've forgotten some pretty basic principles and need to refresh. Now the argument sounds more like "I don't really know, therefore aliens can do it. Easy peasy."

about two weeks ago
top

Do Dark Matter and Dark Energy Cast Doubt On the Big Bang?

Alef Re:Oh good lord. (225 comments)

Heat is a waste product, efficient energy use doesn't necessitate heat.

Not sure if I'm feeding a troll now, but, yes it does. "Using" energy specifically means transforming it such that the entropy increases. The energy doesn't disappear, you can only change its form. And the form where it has the highest entropy (i.e. where you have extracted all useful work), is heat.

All a Dyson sphere does is exploiting the energy difference between its interior and its exterior. All the energy passes through it; the sphere just maximises the entropy as it passes through, in order to perform as much useful work as possible. If it emits anything other than pure black-body radiation, that means it has inefficiencies.

about two weeks ago
top

UK To Allow Driverless Cars By January

Alef Re:Better than zombie drivers (190 comments)

Better for whom? I'm saying is that we agree that it probably would be safer, at least from some average utilitarian perspective. The point you are still missing is that for me as a driver, and most other potential buyers of these cars, it is pretty much pointless to ever switch it automatic drive if we have to be 100% alert all the time and be prepared to intervene to avoid the risk of being charged with manslaughter at any random moment. If whatever happens is on me, and the car company doesn't trust their own car enough to accept liability for what it does, then it sure as f*ck is going to be me who is behind the wheel. And this is how lots of people will reason, whether the car is actually a better driver than them or not. People may be overestimating themselves, but when it's their neck that's on the line, lots of them are going to want to be in charge. That's just psychology. So for these fully automatic cars to be widely adopted, for the benefit of us all IMHO, I think it is crucial that the legal systems ensures that the passengers are not held liable for whatever flaws the car has.

about a month ago
top

UK To Allow Driverless Cars By January

Alef Re:Better than zombie drivers (190 comments)

You are missing the point. The point is that unless the liability is with the car manufacturer, you're basically a riding scapegoat for whatever might go wrong, and realistically with a minimal ability to actually do anything about a sudden situation. If you're smart you wouldn't want that as a car owner.

So it isn't a question of whether the driver-less cars can drive more safely or not; I'm sure they can. It's a question of who's in charge of the car. Is the car maker ready to accept responsibility for what the car maker has programmed it to do? If they're not confident enough to do that, then why would I let it drive for me, instead of just driving myself?

about a month ago
top

Russian Government Edits Wikipedia On Flight MH17

Alef Re:Do you have any hands-on experience ? (667 comments)

Aren't you underestimating the capacity of people to fuck up? The US accidentally shot down Iran Air Flight 655 in 1988 despite Mode III IFF squawks, so it wouldn't be the first time that happened. Maybe they figured it was imposing, or whatever. I tend to go for Hanlon's razor in cases like this.

about a month ago
top

Linux Needs Resource Management For Complex Workloads

Alef Re:complex application example (161 comments)

Of course it's technically possible to transmit packets with essentially 0% loss, and I'm sure there are set-ups that would work under the right circumstances. That's not the point. The point is that each and every component involved, from hardware through firmware to software, is designed under the premiss that it is okay to drop a packet at any time for any reason, or to duplicate or reorder packets. Even if you get it to work, the replacement of any single component, or the triggering of some corner case you haven't tested for (some hardware counter wrapping around or whatever imaginable), might suddenly blow everything up. It's just an insanely fragile system, and you need to have complete and total control of the implementation of every involved component, not just their specifications, in order to ensure that your system meets your spec.

Either switch protocol, or implement something on top of UDP that adds the reliability. There is no other sane way.

about a month ago
top

Linux Needs Resource Management For Complex Workloads

Alef Re:complex application example (161 comments)

Honestly - why are people trying to do things that need guarantees with python?

Oh, you got that far at least? What I wonder is, why are people trying to do things that need guarantees using UDP with no back-communication, no redundancy built in to the protocol, and not even detection of lost packets? External requirement my ass, why do you accept a contract under those conditions? The correct thing to say is "this is broken, and it's not going to work". If they still want the turd polished, it should be under very clear conditions of not accepting responsibility for the end result, and they should be known and understood by all decision makers at the customer. And even so I would be wary.

Otherwise, you're in a prime position for getting hit by the blame when shit hits the fan, either because it doesn't work, or because you didn't tell them that in the first place, since you are supposed to be the expert.

about a month ago
top

Windows 9 To Win Over Windows 7 Users, Disables Start Screen For Desktop

Alef Microsoft's Tick Tock (681 comments)

I suppose this is the next Tick in Microsoft's equivalent of Intel's Tick Tock development model. In Microsoft's case, they get redesign hubris with every other version, then spend the following version back-tracking and undoing all the things they did wrong.

Much like Windows 7 pretty much was a fix-up of Vista, Windows 9 appears to be a "corrected" Windows 8.

about 2 months ago
top

Wikipedia Editors Hit With $10 Million Defamation Suit

Alef Re:booo (268 comments)

Don't worry, this is my night job.

about 2 months ago
top

Steve Wozniak Endorses Lessig's Mayday Super PAC

Alef Re:Major source of corruption is Tax Code not PACs (209 comments)

Obviously, you could say the same thing for any well defined tax curve, more progressive ones as well. It doesn't have to be X%+Y. What you're really saying is that you want all incomes to be treated the same way, and that there should be no deductions.

The reality isn't going to be that simple; for starters you need to define income in some way that is both fair and can't be evaded easily. And if you are too strict about everything being level, you have lost a whole range of financial instruments that are sometimes useful for fine-tuning a market (e.g. internalising externalities like the cost of pollution). But the principle of making the system as simple and transparent as possible I can agree to.

about 2 months ago
top

Steve Wozniak Endorses Lessig's Mayday Super PAC

Alef Re:Major source of corruption is Tax Code not PACs (209 comments)

One reason why a progressive tax system is a good thing is the following: In general, you can get a higher appreciation on your assets if you have more of them. In other words, the richer you are, the faster you can increase your relative wealth. If you set up the differential equations for this, you will notice that the system is unstable, and will asymptotically reach a point where very few own almost everything. A progressive tax system counterbalances this effect, so that there can be an stable equilibrium where some are richer and some are poorer.

Incidentally, this kind of concentration of wealth to a small elite is exactly what we have been seeing in recent decades. Because in practice, the tax systems in most countries aren't really progressive all the way up to the top. If you are rich enough, you either get your income through other means than a salary, which is then usually associated with a lower tax rate, or you escape taxes through more creative measures, like moving your assets to a tax haven.

about 2 months ago
top

America 'Has Become a War Zone'

Alef Re:War of government against people? (875 comments)

What people are saying here is that those claiming that increased gun ownership leads to lower crime rates are using utterly flawed logic. That does not mean that they necessarily argue for the opposite position. In fact, the person you responded to explicitly said that "I'm not arguing for one side or the other".

Why is it so freaking hard for people on Slashdot to understand the difference between a counterargument and making the opposite claim? There is such a thing as "we do not know".

about 3 months ago
top

America 'Has Become a War Zone'

Alef Re:War of government against people? (875 comments)

The burden of proof is on the one making a claim. So when someone wants to claim that gun ownership does not increase violent crime, that person has to prove that claim just as much as someone claiming it does. Pointing to other plausible compounding factors is a perfectly valid counterargument. You then have to eliminate those alternative explanations, just like Copernicus had to for his theory to survive.

You are of course correct that it is a very weak counterargument to simply say that "there could be explanations". But that is not what the GP did. The GP did propose a whole list of other factors that could affect violent crime rate.

By the standard you are setting, nothing is ever disproved, because there could be variables which have not been taken into account.

It's more like "nothing is ever proven", which would be a more or less correct statement with regard to science. It is all about trying to come up with inconsistencies or alternative explanations. When you have thrown everything you've got at the theory and accounted for it all, it is usually accepted.

about 3 months ago
top

Fuel 3-D Claims to be a High-Res, Point and Shoot 3-D Scanner (Video)

Alef Re:What does the back look like? (25 comments)

They use stereopsis for coarse scale depth and photometric stereo (three directions from the looks of it) for finer scale structures. And they seem to be using some tracking target to compensate for motion between these captures. Not a bad idea per se, but I don't think their numbers are particularly remarkable.

I'm not aware of any 3D capturing technique that captures an object "from all sides", unless it's comprised of multiple individual scanners who's data you then stitch into a single model, or a moving scanner (relative to the object's reference frame, so the object could be the one moving), in which case you're really building the model out of lots of tiny scans at different positions (e.g. sheets). In principle, either of these are more or less orthogonal to the choice of scanner. You could do it with this scanner; you'd just put them all in a box and calibrate the extrinsic parameters using some reference object.

The only things that I can think of that could be remotely considered scanning from "all sides" would be something that penetrates the object, like an x-ray CT scanner, ultrasonography or something of that sort, but that would be stretching it.

about 3 months ago
top

Fuel 3-D Claims to be a High-Res, Point and Shoot 3-D Scanner (Video)

Alef Re:Can't have researched competitors much (25 comments)

After having read some on their website, I get the sense that the primary novelty of Fuel3D is not the technology, but who they are marketing it towards. There are plenty of scanners, like the ones you mention, that have equal or better performance characteristics, but they pretty much always seem to be marketed towards either medical applications or manufacturing industries. Fuel3D, on the other hand, have the slogan "Fire up your creativity", visit Maker Faire, and so on. I imagine they hope to break into an emerging market segment before the other guys catch up.

about 3 months ago
top

Fuel 3-D Claims to be a High-Res, Point and Shoot 3-D Scanner (Video)

Alef Re:Can't have researched competitors much (25 comments)

Also, calling their accuracy, by which they mean noise level on a perfectly flat surface, of 0,3 mm on a 35 cm (diagonal) field of view "extremely high resolution" is quite a stretch. High compared to other cheap scanners, possibly, but at least an order of magnitude worse than industrial scanners of similar format.

I think it is an interesting concept to combine photometric measurements with geometric stereo in a single handheld unit, trying to get the best of both worlds, so to speak. But it certainly feels like they are overselling it.

about 3 months ago
top

On MetaFilter Being Penalized By Google

Alef Re:The root problem is... (108 comments)

Isn't the problem that smaller or medium sized web sites don't really have any option? Google is the "start menu" of the Internet for a whole lot of people, so any site that isn't the scale of Facebook or Twitter will be affected by how Google decides to rank them, whether they like it or not.

about 3 months ago

Submissions

Alef hasn't submitted any stories.

Journals

Alef has no journal entries.

Slashdot Login

Need an Account?

Forgot your password?

Submission Text Formatting Tips

We support a small subset of HTML, namely these tags:

  • b
  • i
  • p
  • br
  • a
  • ol
  • ul
  • li
  • dl
  • dt
  • dd
  • em
  • strong
  • tt
  • blockquote
  • div
  • quote
  • ecode

"ecode" can be used for code snippets, for example:

<ecode>    while(1) { do_something(); } </ecode>