Follow Slashdot blog updates by subscribing to our blog RSS feed

 



Forgot your password?
typodupeerror
Get HideMyAss! VPN, PC Mag's Top 10 VPNs of 2016 for 55% off for a Limited Time ×

Comment Re:Don't like bats? (Score 1) 115

Interesting that it is probably spread via the air, too. But that would affect all speciem not only bats.

Only, as bats fly around a room at night over your bed (which happens not infrequently in old houses with bats in the attic, I will personally attest) they emit sonar pulses and if they are rabid, tend to be sloppy. So they emit aerosolized rabies-laden bat-sputum too. Then you can inhale it, or get it on a cut in your skin, or open your eyes and get droplets in your eye, etc. A rabid fox out in open air might run you down and bite you, foaming at the mouth or not, but it isn't that likely to sneeze at you violently enough to infect you through the air. It is also lower than your airways instead of above them. In North Carolina bats are by far the primary vector anyway -- no-bite transmission is just a bonus.

rgb

Comment Re:Don't like bats? (Score 2) 115

As several people pointed out, bats are one of the most common vectors of rabies in the US. And sadly, you do not have to be bitten by a bat to get rabies. There is evidence that just being in the same room with a rabid bat can lead to exposure, probably from aerosolized saliva. Three men (out of the 19 total) who died of rabies over the last ten years had no reported history of contact with bats at all, but had bat-associated rabies viruses. It isn't probable that you will get rabies just being outdoors with bats flying overhead (you have to be super-unlucky, as the bats have to have rabies AND you have to inhale or otherwise introduce aerosolized bat saliva into your system) but it is possible. My wife is a physician who used to work with bats before she went to medical school (and went to Jamaica to collect them because they don't have rabies in Jamaica) and once the evidence that rabies could be transmitted by bats without any bite at all came out, she has actively discouraged even building outdoor bat houses to attract them to our yard.

Yes, one is balancing risks. Mosquitoes carry many diseases (and bats carry a few besides rabies, e.g. histoplasmosis) and some of them can be fatal. Killing mosquitoes with e.g. chemical agents carries risks that have to be balanced against the costs and risks of the diseases they carry. Increasing the bat population will likely enough reduce the mosquito population and chance of mosquito borne infection, but at the risk of increasing the number of deaths due to bat-borne disease instead. I'd guess that the bet is a good one, but (naturally) not for the losers.

There are other efficient mosquito eaters. Purple martins, for example, dragonflies for another. These are not rabies or disease vectors AFAIK. But rabies is an especially scary disease because if you get it, you are basically dead, and 17 out of the 19 deaths reported to the CDC from 1997 to 2006 were from bat-related variants of the rabies virus (so even if the bite was e.g. from a fox or racoon, the fox got it from a bat). It is like mad cow disease -- scary because you may not even know you were exposed and then at some later point -- possibly years later for vCJD -- you develop the incurable disease and die. Because vCJD is so difficult to detect or diagnose, you might even die without anyone ever knowing why. If you remember the panic over mad cow disease in the US, try to also remember that more people die of bat borne rabies in three years that have ever -- to the best of our current knowledge -- died of vCJD in the US, and of the four that HAVE died, all of them are believed to have contracted the disease overseas.

The flu, on the other hand, kills well over 100 children every year, and many times that many adults. Yet people don't fear it enough to even get vaccinated, all too often, because MOST people who get it don't die (but a lot of people get it!). It's not rational. Go figure.

rgb

Comment Re:2 weeks later (Score 0) 296

But that doesn't work if they have probable cause to search it, any more than saying "sorry, you can't come in just now" works if they have a warrant to search your house. The constitution only protects against UNREASONABLE search and seizure, and the historical definition of this has been "enough to convince a judge to issue a warrant". So you can plead anything you want, but you'll stay in jail until you cough up the keys, be they keys to your house or to your encrypted phone or laptop. I learned this, BTW, directly from FBI agents at a crypto conference I attended many years ago, where the rest of the discussion centered on cracking. The feeb was a lot less concerned -- then -- with cracking encryption than you might have thought, simply because they already had adequate eternajail means to gain access in cases with probable cause. This might even have been pre-9/11 -- since then they have clearly come to see the importance of being able to crack things even when somebody is CONTENT to sit in jail forever relative to what would happen if a file were decrypted, or to be able to crack the encrypted files of dead terrorists in the aftermath of events.

Note that Ithe above is not commenting on what is or isn't good or just or right here. Only that there is a constitutionally approved and commonly enough used way to mandate access to encrypted files, and it doesn't involve NSA-level resources or techno-spooks or back doors into encryption routines. It involves getting a warrant. To comment NOW -- that's by far the way I'd prefer it. A warrant or court order at least gives you some chance to defend yourself -- probably not invoking the fifth, but perhaps challenging the strength of the evidence used to get the court order. It is also done in the light of day. I think what a substantial fraction of the world is worried about is that Russia is regressing to where no court at all is required, no oversight, and where they might literally use a wrench -- or a testicle-taser -- to coerce the keys on demand.

One might worry about this in the United States as well. Or "by" the United States in places like Cuba. IMO both Trump and Clinton are perfectly willing to use non-constitutional means against perceived enemies or possible terrorists -- Clinton demonstrably so, Trump by his overblown jingoist rhetoric.

That's why I'm voting for Cthulhu. With Cthulhu you know where you stand. If elected, It promises to eat all of the enemies of the United States first, in some cases only a little bit at a time... Vote for Cthulhu: "No Lives Matter"

rgb

Comment Re:2 weeks later (Score 1) 296

Which is the "official and legal" way to obtain access to encrypted information in the US. The "wrench" is called a "subpoena" or a "warrant" issued by a judge for probable cause, combined with an unbounded eternity in jail for contempt of court until you cough up the keys. Yes, you can be in prison for life without even having a trial for ongoing contempt of court. Every day is a new offense and another day in jail.

I'm even reasonably comfortable with that. At least there is some sort of due process with a nod to the constitution and the rights of citizens. The PROBLEM is all of these agencies that want to just be able to browse all the files in existence looking for trouble, or decrypt any file they want (or any phone or laptop they want) without going through the constitutionally mandated process of obtaining a warrant etc to use as a wrench. I don't think they have any clue as to the computational implausibility of what they are asking, as well. I'm personally good for a few hundred GB of data -- call it a TB. Some of that goes over the internet, encrypted, every day. Just to send or receive it at 200 Mbps (premium service) often takes me an hour or two. Now multiply.

The only way to accomplish their goal is to build a powerful AI agent into every operating system in the world that monitors every single byte typed or saved or displayed on a system, the ultimate electronic big brother. Then network the whole thing together into a nation-spanning compute cluster with hierarchical decisioning at all levels. Because categorizing the human interpretive MEANING of any given content is much more computationally intensive than moving the bytes around (it requires our enormously complex human brains to do it) we can anticipate that every laptop and desktop and server would need to devote at least 90% of its resources to bigbrotherd operation. And bigbrotherd hooks would have to be built into the hardware, or it would be too easy to write kernels without it, or with a bigbrotherd that runs in a sandbox to make the global network happy but leaves the user the actual system running free and clear, especially with open source OS's in abundance that cannot easily be controlled.

And this will all happen approximately when hell freezes over. So don't worry about it! In Putin's Russia, keys encrypt you!

rgb

Comment Re: If this is correct it should be easy to check (Score 1) 299

My biggest concern is the free lunch thing -- second law violation is -- unlikely. Literally. Energy quanta and attendant uncertainty is all great, but it can't be used to generate free energy. Momentum uncertainty doesn't seem as though it could be used to generate free momentum. And finally, I am deeply skeptical of violating the relativistic relation between (massless) energy and momentum.

But sure, anything is possible. And no doubt, a reactionless drive would be very cool and enormously useful, maybe even enough to permit the exploitation of near-earth space. As I said, even mm/sec^2 accelerations are plenty to get around if you can afford to take your time to get places and all your ship needs to run is sunlight. Light sails would be equally cool, except for that pesky E/c bit, and even so NASA is testing using those to at least overcome high orbit drag and keep satellites up longer without an expensive boost (at whatever acceleration they can produce, maybe microns per second squared, dunno).

I love science fiction, and would like nothing better than to see new physics that enables all the things that forty years of studying, doing research in, and teaching physics have taught me are just plain impossible (barring new physics). But at the same time, I can't suspend my disbelief the way I do with e.e. smith's space opera (with its TERRIBLE physics) when it is the real world. Either way, time will tell. It usually does.

rgb

Comment Re: If this is correct it should be easy to check (Score 1) 299

C'mon, if they can program experiments that prove that there could be no hidden variables that explain the randomness in quantum mechanics (using, of course, hidden variables that simulate the randomness in quantum mechanics in their computer) they ought to be able to fix this bug...

rgb

Comment Re:Not making any sense to me (Score 1) 299

Well, I am a theorist that teaches graduate level CED and a science fiction author, so I'm really good at making stuff up that sounds plausible. But let's maintain perspective, please. The point of my post is that energy and momentum are strictly conserved in the two slit experiment in the observable universe. Sure, the missing energy/momentum "could" be in a direction we know nothing about, but that is pretty implausible, basically just science fiction so far. We would need way more evidence before we started to take that sort of hypothesis seriously.

Put it up in space, power it with solar cells. One ought to be able to build one that should produce an acceleration of 1 mm/sec^2, "forever", off of sunlight. That's a delta-v of around 200 mph/day, unmistakable, and if it can produce this without losing mass and using only sunlight as energy input, CED, QED, and the second law of thermodynamics are going to all be very sad... as we will have built a machine that violates the second law of thermodynamics, (electrical) energy into work "with no other effect".

Until then, let's remain just a bit skeptical, shall we?

rgb

Comment Re: If this is correct it should be easy to check (Score 3, Interesting) 299

Oh, I was just being facetious. As you say, physics has undergone multiple "complete rewrites" (not really, but yeah, aristotelian->newtonian, newtonian->quantum, galiliean->lorentz are at the very least very, very serious revisions of the way we think even if they do eat their predecessors and continue to support their successful results).

However, the law of conservation of momentum is one of those things that it is difficult to muck with, without requiring a pretty complete rewrite. If you put this thing in deep space and it just moves (accelerates) without shooting mass/energy/momentum out in some form, it would make me -- and physics -- pretty sad. I have to put it in the same category as the prior reports of transluminal neutrinos and the like. Always possible that they are true, but claims that will change everything require the most solid of evidence, and so far this is in the category of any number of famous "marginal" results that turned out to be accidents of one sort or another.

At the end of the day, of course, physics is KNOWN to be incomplete. Maybe the damn thing is acting as a darkon drive and is through a process we do not understand converting microwaves to darkons to momentum through some unknown resonance process. Maybe it is evidence for a dual universe where charge and spacetime are reversed, and the cavity somehow couples the two so it is pushing off against its shadow twin. Maybe we can make up a dozen theoretical explanations for it -- eventually, if necessary.

But for the moment it, like transluminal neutrinos, is still in the "probably magic" category pending extraordinary evidence to back up the extraordinary claim. Maybe if NASA launches one into orbit with its own solar power system and runs it for a few years, during which time it promotes its orbit in unmistakable ways. It doesn't look like it needs to mass more than a few hundred kilograms total, solar panels ought to be able to provide it with at least a kilowatt or three, so getting a thrust of around a newton should be possible. A newton may not sound like much pushing 100+ kg, but an acceleration of 1 mm/sec^2 over a day adds 84600 mm/sec, or roughly 90 m/sec, or (multiplying by 9/4) roughly 200 mph. It wouldn't take many days to make a clear, unmistakable alteration in the orbit. With modern instrumentation, I would think "one" (or even less) would suffice. Even 20 m/sec/day acceleration at a tenth of this ought to show up almost immediately.

In space, there is nothing nearby to push against. One can actually use the observed thrust itself to measure the mass of the satellite and see if it varies over time (eliminating the possibility that mass is being thrown out somehow assuming that it does not, as it should not). With solar cells with a cross-sectional area of at most a few square meters, radiation pressure is utterly incapable of producing this acceleration because you have at most Pr = S/c to work with, and S is order of 1400 W/m^2 and by the time you divide by c you have basically nothing left (as observed elsewhere in the thread).

At that point, if it accelerates as advertised, Classical Electrodynamics is dead as a doorknob, and QED is walking wounded as it still works off of CED and at the microwave level and high power, "photons" ought to be irrelevant anyway. Note well: you are converting a substantial amount of incoming electromagnetic energy directly into work "with no other effect" if it works as advertised. So even the second law of thermodynamics is going to be very sad. I'm tempted to quote Eddington:

"The second law of thermodynamics holds, I think, the supreme position among
the laws of nature. If someone points out to you that your pet theory of the
Universe is in disagreement with Maxwell's equations - then so much the worse
for Maxwell's equations. If it is found to be contradicted by observation -
well, those experimentalists do bungle things up sometimes. but if your theory
is found to be against the second law of thermodynamics I can give you no hope;
there is nothing to do but to collapse in deepest humiliation."

There's some wisdom there...

Comment Re:Not making any sense to me (Score 1) 299

Elementary E&M. The EM field, quantum or not, "particle like" or not, is a FIELD. If you set up the two slit experiment there are places on the screen where the fields from two coherent sources (slits) are out of phase and no energy or momentum is transferred. Even if you turn the intensity down to where one "photon" at a time goes through the pair of slits (yes, it goes through BOTH slits, or at least the FIELD does) the photons appear only in the BRIGHT bands where the fields are IN phase. No energy or momentum is transferred to the dark bands.

So the correct answer is that if there is a volume of space where the photons are out of phase and cancel, there is another volume of space (at a different angle) where they are IN phase and do NOT cancel, they add. Energy and momentum are conserved. The light just goes only to places where the FIELD addition is coherent and at least partly in phase. QED.

The photon is its own antiparticle, BTW.

This drive is (so far) like a hypothetical box in space containing a kid with a basketball. He keeps bouncing the ball off of one wall so that it recoils off and he catches it. Every time he bounces it off the wall, however, the box recoils away from the kid, and gradually builds up an appreciable momentum.

So all we need to explain this drive is a way for the kid to catch the ball, inside the box, and not just transfer the exact same momentum back to the other side of the box that he's standing on in order to be able to throw the ball in fhe first place.

rgb

Comment Re: If this is correct it should be easy to check (Score 2) 299

Ah, but this drive is MAGIC, and doesn't obey the laws of conservation of momentum and equal action/reaction and all that. It pulls itself up by its bootstraps. It gets rich by selling itself rocks. And if it violates momentum conservation it almost certainly violates energy conservation too. Chaos ensues. The Universe collapses in a puff of physical inconsistency.

Or, as it moves forward, it kicks something else backwards. There really aren't a lot of choices here that don't require a fairly complete rewrite of physics. Even at the quantum level, outside of irrelevant borrowings at the scale of hbar, these conservation laws hold and it is pretty well believed that they hold globally for closed systems and that energy and momentum and angular momentum are in detailed balance in interactions. That's the entire basis of field theory. You're talking about a nearly complete rewrite of field theory (along with everything else).

Or, it kicks something backwards. Or, something else is going on. I'll take a heap 'o convincing, though, before I throw out physics in favor of "magic".

rgb

Comment Re:ALIENS. (Score 1) 220

If I had any ligoites in my addressbook, sure, but lacking that, posting on /. is a good way to proceed. OTOH, reading the wikipedia page would probably do it too. At the moment I'm making up a physics final and don't have time -- I was just dangling bait to see if I could get a lazy answer in the meantime...;-)

Comment Re:ALIENS. (Score 1) 220

I think you slipped a decimal. The LIGO observatories are roughly 3000 km apart, so a straight line lag between them is around 10 milliseconds. A lag of 1 millisecond meansi that the (essentially plane) wave came in at a small angle relative to the perpendicular plane separating them. The triangle involved would (conveniently enough) have a short leg around 300 km long, and that's still a small angle so without a calculator roughly 0.1 radians on one or the other side of the perpendicular plane. I'm not certain how they manage to set the azimuthal angle and decide whether the source is on the northwest or southeast side of the plane (at the moment of detection, which then has a very particular orientation relative to universal coordinates as the earth orbits and rotates) -- maybe they use the shift in the lag AS the earth rotates to do azimuthal triangulation if the signal is long enough, maybe they use multiple detectors at right angles to each other to get an extra angle -- I suppose I could look, but detecting signal lags across meters is easy enough with modern electronics (nanosecond plus time resolution) so they could even do both. It would have been and still would be a lot more precise if they had three, or better, four detectors and could do honest to god 3D triangulation -- they aren't going to do parallax until they put a second detector on (say) the moon or at the lagrange points but they could get a very precise line to the event that way.

Any LIGO-ites on /.? Surely somebody who does this is around to comment with something other than references to the mass of their male parts? Which, on the scale we are discussing, is truly infinitesimal (reminding me of the flea and the elephant, but that's another story...:-)

rgb

Comment Seriously? (Score 4, Insightful) 159

The "scientists" at Cornell who are getting headlines with this breaking news haven't the foggiest clue how far away the nearest alien intelligent species is from Earth. Possibilities range from living here already among us or lurking in the solar system to "there are no alien intelligent species in the Cosmos", we could be unique. If you assume -- not unreasonably -- that evolution of advanced life requires an extremely unlikely accident -- like a collision with a proto-planet that is just the right size to strip away some atmosphere components and deposit others and rearrange the distribution of massive elements in the developing crust and then produce a moon that initially is very close and produces huge tides, plus a magnetic core, plus the right distance from the right sun, plus the good fortune not to be hit AGAIN just as intelligence is teed up, plus the enormous good fortune of the developing species making it over the self-extinction hump -- we might be alone in the entire galaxy or in very rare company extragalactically, even with a trillion trillion star systems to choose from. Or, the odds could be a D&D 20 sided dice roll per star. We just don't know. There is no evidence, and our theories of planetary evolution and abiogenesis are just that -- theories with very little substantive evidence to support them.

Then there are the other silly aspects of their claim. It is rapidly looking like a developing civilization is likely to have only a narrow window where they radiate a substantial amount of organized radio wave energy, so one has an even narrower window for retarded detection. Also that emitted (wasted!) energy at its peak is on the order of maybe a megawatt or two in any given channel on its brightest day, and the 1/r^2 law is pitiless. Just one light year away your 10^6 watts are spread out across 4\pi (10^15)^2 ~ 10^31 square meters. Let's see: 10^6/10^31 = 10^{-25} watts per square meter. If you turned an entire planetary surface into a directed antenna, it would have a cross sectional area on the order of 10^14 square meters, leaving you with 10 whole trillionths of a watt receiver power. Sure, why not, a piece of cake we can amplify that and resolve signal from noise -- using a planet-sized antenna and black magic.

So a better answer is that we will never be visited by space aliens who "pick up our TV signals" any more than we will pick up their signals. If some NEARBY civilization is crazy enough to point a directional, tight beam radio station right at the solar system and pump it with a terawatt or so, sure, maybe we could receive it here. But resolving the waste signal of a civilization order of tens of light years or more away? The amazing thing is that anybody manages to get this sort of thing funded. Simple arithmetic makes a fairly powerful argument that any SETI effort is a complete waste of time and money. No matter how cool -- and dangerous -- it might be.

rgb

Comment Re:No morals to be found there (Score 2) 170

I agree. Apple is just weird, sort of a kinder gentler flakier version of M$. They run Unix as their OS, sort of, rely on the open source community for a pretty good chunk of their back-end Unixoid software at least, do HAVE a decent amount of OSS available, but at the same time they emulate the empire of evil at inopportune times.

I keep wondering if one day they are going to learn the Sun Microsystems lesson the hard way. You can be a hardware company, or a software company, but if you try to be both you are just asking for it. Apple has survived balanced on that line, but only because they stopped being a "computer company" for the most part and focused on the children of the humble PDA rearranged into PAD or POD. There (including their phone) they've been able to continue to make consumers buy Apple Koolade -- for now. But they (like Sun) are a high margin sales company. They survive only as long as they remain a premier brand that people will pay a premium for, because you PAY a premium compared to Android devices built much more along OS lines. M$ has failed repeatedly to get any suckers to buy their even more overpriced hardware with integrated software.

We could be moving solidly into the next phase of the small digital device, where one cannot really add more functionality than they already have, where they are already fast enough to do almost anything most people want them to do, where the only dimensions for added value are things like longer battery life or better screens. In the PC world that was signalled by a crash in prices to where survivors survive on the thinnest of margins and where once mighty "name brands" can only eke out a continued, marginally profitable existence but can no longer pay for a dedicated premier sales force and so on. Such a market change could crush Apple (as it crushed Sun, DEC, and countless others during the great Unix shakeout a decade or two ago) and maybe even M$ as well. But M$ still has what remains of the "real computer" world by the balls with its sales agreements, and even though it isn't high margin sales any more, it is nearly free money that they can continue to extort from system vendors indefinitely, and they obviously plan to transform their OS into a rental commodity that you have to renew annually instead of something you buy once to monetize it even after it leaves the store.

A brave new world, where we pay the M$ tax not once, but every year, with Apple not far behind (I'm sure). But what do I care? I've used nothing but Linux for decades at this point -- even my WinXP VMs haven't been booted for over a year. With Steam, even the game issue is largely moot, although coverage is far from perfect or universal. Don't have much time for games these days anyway, sigh.

rgb

Slashdot Top Deals

It is not every question that deserves an answer. -- Publilius Syrus

Working...