Please create an account to participate in the Slashdot moderation system

 



Forgot your password?
typodupeerror

Comment: Re:Thermodynamics (Score 1) 312

The reason why this planet is around 300K is that the surface of the sun only fills a small solid-angle of our sky. Without the 3K background, our planet would heat up until photosynthesis became entropically unviable (by going in reverse as often as not).

When the CMB was 300K then, to prevent water from boiling, a planet would need to be much further from its sun. This would make it very dark; photosynthesis would need to be extremely efficient (which is difficult to engineer, or unlikely to arise biologically).

Comment: Re:Wot??? (Score 2) 173

by CesiumFrog (#39447959) Attached to: Scientists Discover Link Between Trees and Electricity

> Everyone knows that trees give us all oxygen so we can breathe

I certainly don't know any such thing. In fact I thought forests were net zero oxygen because when trees die the decay of the tree consumes as much oxygen as the tree produced during its life. Not to mention that of course at night the tree is burning the sugars it made during the day by photosynthesis.

If that were true, why does the global atmospheric CO2 concentration (whilst obviously increasing year after year) have a seasonal oscillation with its phase matched to the growing season of the northern hemisphere (which has an excess of forests rather than ocean)?

Plankton is where there is a possible net oxygen increase because when they go dead they can sink, and when that happens they don't decay.

It might be the production of carbon-rich soil that you're overlooking.

Comment: Re:TFAs fantasy world (Score 1) 463

by CesiumFrog (#39445725) Attached to: Surviving the Cashless Cataclysm

If you buy contraband once, you can immediately identify a large number of other wallets guilty of the same purchase, and you can trace each one's transaction history until they interacted with a legitimate business, and then you just subpoena for shipping addresses.

That is possible if the seller only ever uses one address. You could do it that way if you wanted, but it's not the default way the software works, nor is it how it's meant to be used.

No, it can also apply if the seller has more customers than addresses, or if statistical analysis can recognise that the seller is routinely aggregating that set of wallets together in order to spend the income (say, buying a boat or a trolly of groceries).

Comment: Re:TFAs fantasy world (Score 1) 463

by CesiumFrog (#39437881) Attached to: Surviving the Cashless Cataclysm

Your conclusion betrays a lack of imagination. And also a lack of in-depth knowledge about the system you are criticizing.

Bitcoin is a system of numbered bank accounts with public transaction histories, where the only person who knows your bank account numbers is you, and you can have as many bank accounts as you wish at will. It is not only non-trivial to trace (wallets are a collection of addresses which have no tangible relation between each other, and each transaction reveals partial information about the relation between addresses), it is impossible in most cases, especially if you take certain precautions. You make it impossible by keeping the relation out of the chain.

So, you want to purchase contraband? Just use two different wallets. One wallet that can potentially be traced to your identity, and one that can't be. Is it too hard to do?

And how do you get money into your contraband-wallets, without it being traceable back to you?

Comment: Re:TFAs fantasy world (Score 1) 463

by CesiumFrog (#39437335) Attached to: Surviving the Cashless Cataclysm

Bitcoin is fully anonymous. I think you are confusing authenticated with anonymous.

So not true.

If you buy contraband once, you can immediately identify a large number of other wallets guilty of the same purchase, and you can trace each one's transaction history until they interacted with a legitimate business, and then you just subpoena for shipping addresses.

Bitcoin is a system of numbered bank accounts with public transaction histories. Just because the accounts aren't listed by name doesn't mean it wouldn't be trivial for accountants to trace them back to people. (You can only be anonymous if none of your interactions are with any parties who could ever compromise you, in which case it isn't very useful as an alternative currency.)

Science

Undersea Neutrino Observatory To Be Second-Largest Human Structure 120

Posted by Soulskill
from the original-xbox-controller-still-king dept.
cylonlover writes "An audacious project to construct a vast infrastructure housing a neutrino observatory at the bottom of the Mediterranean Sea is being undertaken by a consortium of 40 institutes and universities from ten European countries. The consortium claims that KM3NeT, as it is known, will 'open a new window on the Universe,' as its 'several' cubic kilometer observatory detects high-energy neutrinos from violent sources in outer space such as gamma-ray bursts, colliding stars and supernovae. On the scale of human constructions, it will be second only to the Great Wall of China."

Comment: Re:its the ecosystem stupid (Score 1) 73

by CesiumFrog (#37312300) Attached to: Using Stem Cells to Save Endangered Species

TFA is about northern white rhinos, which are critically endangered by heavy poaching.

So actually for some species, human-caused extinction could be avoided simply by such artificial reproduction techniques. In fact this may be the only way, since there are now so few of these rhinos left that we don't have time to try more experiments to find out how to encourage breeding. (We certainly can't figure it out by observing wild populations, since we've poached those to extinction already.)

Also, if we had a technology to reproduce these animals at a much faster rate than is natural, then poachers (who are using other recent technology to eliminate these animals at a much faster rate than is natural) would cease to be a problem. Posters above have already made the case for preservation by domestication, but in this case (despite all our attempts to eradicate the ridiculous belief that keratin obtains some mysterious power when taken from some phallic icon) clearly the economy already does have a use for these rhinos (and lack of reproductive technology is the main obstacle to farming them, so we would not even need to modify these animals to be more appealing). Thus this technology could easily pay back its own development, even without considering the spinoffs that such iPSC germ cell research would be anticipated to advance human medicine.

But it's still valid for you to emphasise the ecosystem (or would be if you weren't unconstructive). Even if not applicable to these particular animals, habitat encroachment is certainly becoming the prime factor in the incredible rate of current extinctions. This is devastating, since our understanding of DNA is only just advancing to the point that we recognise what a wealth of information is being lost with diminishing biodiversity, it's like burning the library that stores millions of years of engineering insights which can guide biotechnology (for example, most pharmaceuticals even today are discovered, not invented, and their processes of chemical synthesis are similarly not only inspired by biology but often too difficult or more expensive to synthesis except through harvesting natural components), not to mention the encoded historical record (without which our understanding of our past must always have larger gaps), and abstract value (which only grows as are progressively less preoccuppied labouring for bare necessities). Hence the huge importance that we curb the raw growth (rather than development) of the economy, like we are finally only beginning to do in the issue of carbon. And that we halt this planet's human population growth (and it looks like being a long time before we have somewhere else to populate): we educate women (and quit forbidding family-planning tools while we're at it) and do more to eliminate extreme poverty (rather than using the reality that a portion of funds will leak and miss our target as an excuse to not contribute to the target at all). We generally need to adopt a more progressive stance, and quit bashing science, decora. Each extinction may cause a cascade. Who knows what other (perhaps little-known) species may be indirectly dependent on the existence on these rhinos for example. Certainly there will be species-specific parasites that directly depend on the host, which may not be as appealing but still embody potentially-useful knowledge. We only recently realised how organisms unique to a panda's gut are relevant to the development of biofuels.

(didn't really intend anonymous)

Australia

Pricing: Apple Defies Australian Government 440

Posted by Unknown Lamer
from the higher-prices-down-under dept.
daria42 writes "This week it was revealed that Apple has still not responded to Australia's Federal Parliament on the issue of why the prices of its products are significantly higher in Australia than they are in the US, five months after the query was first raised by a member of parliament from Australia's governing Labor party. Apple has refused to issue a statement on the matter or even acknowledge the issue. What will it take to get Apple to open up — a national enquiry?"
Transportation

8 Grams of Thorium Could Replace Gasoline In Cars 937

Posted by Soulskill
from the it's-cheap-on-the-auction-house-too dept.
An anonymous reader writes "Thorium, an abundant and radioactive rare earth mineral, could be used in conjunction with a laser and mini turbines to easily produce enough electricity to power a vehicle. When thorium is heated, it generates further heat surges, allowing it to be coupled with mini turbines to produce steam that can then be used to generate electricity. Combining a laser, radioactive material, and mini-turbines might sound like a complicated alternative solution to filling your gas tank, but there's one feature that sells it as a great alternative solution: 1 gram of thorium produces the equivalent energy of 7,500 gallons of gasoline."

Comment: Re:Loss of mass (Score 1) 133

by CesiumFrog (#36883716) Attached to: Heat 'Most Likely Cause' of Pioneer Anomaly

That's 14 milligrams, not 13 micrograms. And it may not be negligible if the mass is ejected directionally.

Google "1 kW / c / 250kg". The momentum of 1kW of photons could accelerate the Pioneer by 10^-8 ms^-2, if it were all emitted in one direction.

The anomalous acceleration we want to explain is about an order of magnitude smaller than this figure. Hence, TFA.

Comment: Here's the solution to the herd mentality flaw (Score 1) 393

by CesiumFrog (#36078168) Attached to: Ask Slashdot: Going Beyond Comment Threads?

The problem with the /. system is that it's one-size-fits-all. A better system would expose the raw moderation data to the client.

For example, consider a post that is highly informed, reasoned and articulated but expresses some viewpoint which herd sensibilities oppose: So it gets 10 positive and 10 negative mods, and the current system therefore buries it amongst the least significant posts (the system instead elevates a swathe of highly similar posts expressing the majority viewpoint, ultimately just reinforcing one potentially narrow mindset). Unfortunately, the posts I most want to read are the ones that expose me to viewpoints outside of my own. I want to preferentially read the posts that generated a strong-yet-controversial reaction (e.g., ranking posts more according to sum of absoluted mods, rather than the sum of signed mods).

But this is only one alternative ranking scheme. For example, I also want to cancel out the tendency to arbitrarily favour the earliest posts over ones contributed a couple hours later, so I might rank according to rate-of-moderation (calculated using timestamp from the post) instead of accumulated total. Or somebody might develop a Last.FM (librefm) style model, which analyses which other mods tend to agree with the mods who favour your favourite posts, and therefore recommends the posts each of us will personally most enjoy seeing. Or, some people might prefer to build their own trust networks, and preferentially read posts recommended by moderators endorsed by authorities they respect. (For example, on a cutting edge science topic, I'd like to first hear from people who have actually studied related fields, leaving the general sci-fi reference jokes and alternate theory speculations further down the page.)

We have to recognise that /. is already exceptionally good compared to most forums in the world. Try discussing the physics of climate change on physicsforums and you very quickly see the downsides of having some fixed set of "expert" moderators imposed from above (fallibility, autocracy, censorship, etc). The key at /. is automation and democratisation. But it could go further than that, by also democratising the post ranking scheme, and the site administrators only need to facilitate that. (Just like the users themselves perform the labour of eliminating spam from /., so too the users could burden responsibility to evolve superior ranking schemes.)

Communications

RIM Co-CEO Cries 'No Fair' On Security Question 329

Posted by timothy
from the you-can't-ask-me-that dept.
bulled writes "When asked about letting governments in Asia and the Middle East into the 'secure' message service used by their BlackBerry devices, Mike Lazaridis, the co-chief executive of RIM, walked out of the interview and said, 'We've dealt with this, the question is no fair.' By 'dealt with,' we can only assume he meant: 'been paid handsomely to let governments read what they wish.'"
Biotech

Improving Nature's Top Recyclers 41

Posted by Soulskill
from the i-bet-they're-twice-as-productive-in-michigan dept.
aarondubrow sends in this snippet from an article at the Texas Advanced Computing Center: "Over billions of years, fungi and bacteria have evolved enzymes to convert abundant cellulosic plant matter into sugars to use as energy sources to sustain life. It's a great trick, but unfortunately, these enzymes don't work fast enough...yet. So computational scientists at NREL, in collaboration with a large experimental enzyme engineering group, set about trying to understand and design enhanced enzymes to ... lower the cost of biomass-derived fuel to serve the global population (abstract)."
Earth

One Giant Cargo Ship Pollutes As Much As 50M Cars 595

Posted by kdawson
from the stink-pots dept.
thecarchik writes "One giant container ship pollutes the air as much as 50 million cars. Which means that just 15 of the huge ships emit as much as today's entire global 'car park' of roughly 750 million vehicles. Among the bad stuff: sulfur, soot, and other particulate matter that embeds itself in human lungs to cause a variety of cardiopulmonary illnesses. Since the mid-1970s, developed countries have imposed increasingly stringent regulations on auto emissions. In three decades, precise electronic engine controls, new high-pressure injectors, and sophisticated catalytic converters have cut emissions of nitrous oxides, carbon dioxides, and hydrocarbons by more than 98 percent. New regulations will further reduce these already minute limits. But ships today are where cars were in 1965: utterly uncontrolled, free to emit whatever they like." According to Wikipedia, 57 giant container ships (rated from 9,200 to 15,200 twenty-foot equivalent units) are plying the world's oceans.
Science

Glass Invisibility Cloak Shields Infrared 115

Posted by kdawson
from the moving-on-up dept.
An anonymous reader writes with the latest advance in the quest for a cloak of invisibility (Michigan Tech University's press release). We've been following this research as it develops; here are stories from each of the last four years. "Invisibility cloaks are slowly working their way up to shorter wavelengths — starting at millimeter-long microwaves and working their way to the nanometer wavelengths of visible light. EETimes says we are about half way there — micrometer wavelengths — in this story about using chalcogenide glass to create invisibility cloaks in the infrared. Quoting: 'Invisibility cloaks cast in chalcogenide glass can render objects invisible to infrared frequencies of light, according to researchers at Michigan Technological University... Most other demonstrations of invisibility cloaks have used metamaterials composed of free-space split-ring resonators that were constructed from metal printed-circuit board traces surrounded by traditional dielectric material. The Michigan Tech researchers... claim that by substituting nonmetallic glass resonators made from chalcogenide glass, infrared cloaks are possible too...'"

It isn't easy being the parent of a six-year-old. However, it's a pretty small price to pay for having somebody around the house who understands computers.

Working...