That works amazingly well for me, actually...
In fact, I like the "moron point" add-on for so very many things. So many it would be difficult to make a list...

So do stone-cold sober drivers. So do old people. So do young people. So do drivers who are high, but who also had a few beers. The reason god invented statistical analysis was so that we could stop using anecdotal reports of "knowledge" as if they were fact.

That said, pot is like alcohol in one important respect, and that is that one can have a lot or a little THC on board, and then, there are different cannibinoids with different action on the brain, and since the THC tests are comparatively insensitive to both concentration and type compared to blood alcohol tests it isn't so easy to build a table that extracts the risk associated with driving while doing
bong hits of resin-saturated buds every few miles compared to driving having smoked part of a joint of everyday weed two hours earlier. You remain THC positive for days after smoking, but are at (possibly) increased risk for at most hours, where with alcohol one metabolizes roughly 1 drink/hour (perhaps a bit less if you get a lot of alcohol on board instead of a little) and can remain at increased risk for six or more hours if you drink heavily at a party.

However, TFA (which I actually read, as the subject interests me) basically showed that across all categories of pot use, there is a very small, statistically insignificant increase in risk of accident. They noted a number of studies that show decreased risk for moderate pot intake -- the theory here being that stoned people know that they are stoned and drive extra-carefully and end up safer than your average cell-phone-toting, conversation distracted, overworked and stressed out driver. This may well be cancelling out part of the increased risk associated with drivers doing hits while they drive. But designing a study to reveal this sort of thing would be challenging and in some sense isn't useful. Common sense suggests that it is dumb to do bong hits while driving at high speed down an interstate, especially while washing it down with a cold beer on the side, just as common sense suggests that it is dumb to drive without a seat belt or while texting or while fumbling with a music player or when one is really sleepy. Some (many) people, myself included, have done one or more of these things at one point or another in their lives.

The evidence, however, supports at most the citation of individuals caught driving WHILE smoking weed, not people who have THC in their bloodstream. That's the whole point of the study. Unless/until we have better tests that can easily detect the quantity and type of THC in your brain and studies based on those tests that are sensitive to and demonstrate the increased risk you assert is there based on anecdotal evidence (and sure, common sense) for some specific levels of concentration, the risk based on the mere presence of THC in the blood is substantially less than the risk associated with drinking a single beer. Field sobriety tests measuring actual intoxication are going to be more valuable than "just" the presence of THC.

rgb

That's right, I like to include Nitrogen and Phosphorus and Uranium in my beer. None of this wussy carbon, oxygen and hydrogen. You know you've been drinking when you drink molten thorium fluoride salts.

Oh, you mean from hydrogen and carbon dioxide only...

Never mind.

Ah, that makes a lot more sense. So it was set up to basically do a reverse greenhouse -- reflect sunlight with very high albedo (not strongly absorbed because the non-humid atmosphere is largely transparent to sunlight) but emit on its own in bands that are counterposed to the greenhouse gas bands. That I can believe, I think. No second law violation because it is stuck between two reservoirs, one at 6000 K (sunlight), one at 3 K (space) and in thermal contact and quasi-equilibrium with a third (its environment). Interesting.

So during the day it would absorb less heat from the sun, and would radiate what it did absorb away in a comparatively narrow band. There are still some heat flow issues -- in order to be in dynamic equilibrium via heat loss through the smaller window, it has to get hotter than it would the same as an ordinary material with outgoing radiation merely blocked and reradiated down in the greenhouse bands, but it is decoupled from those bands instead of being in balance with them.

One does have to wonder what happens to greenhouse radiation incident on the material from above. It can't be absorbed because of Kirchoff's Law. So it must be reflected too?

rgb

No problem with resonant fluorescence or colored objects and so on. It's the notion of something being in thermal equilibrium with (say) 300 K but radiating only at a single frequency being a more efficient cooler. That's basically a picture of a thermal refrigeration laser (at least, if one puts the optically active material in between two mirrors). It requires a very peculiar quantum structure and as I said, one has to worry about detailed balance because the ordinary bouncing of internal thermal energy has to keep the resonant level "pumped" without itself radiating. It is metaphorically very close to a nanoscale Maxwell gate that only lets molecules through if they are warmer, or cooler, than equilibrium so that a gas spontaneously separates into hotter/cooler volumes, although as you say technically it might not violate the 2nd law by cooling to a reservoir at 3 K bypassing the material in between and hence enable a perpetual motion machine of the 1st kind. Odd to say the least.

I don't remember it on /. but I'll look around. Usually I catch anything of interest in optics but sometimes topics cycle fast enough in my feed that I don't see them before they breeze on through. However, if the time frame is "very recent" that helps. I suppose I can see what google can turn up. Thanks.

rgb

Reference (to the new meta-material)?

I'm not disbelieving, but given the nature of thermodynamics and radiation, I'm not believing until I read the paper(s) and see some evidence that it works. There's the detailed balance issue.

Then one can look at the cost-benefit. If it is cheap, it absorbs heat and radiates it away in a single channel, and you can make roof tiles or roadway surface out of it, it might make some sort of difference. Sadly, this is what I'm having trouble with because with a single sharpish frequency one is dangerously close to a Maxwell Demon, take "heat" and radiate it away as a single frequency.

rgb

And when the day comes that we can build general purpose robots, your obvious retort #2 will be apropos, although even then one will have to compare the operational efficiency and cost-benefit of a really, really good firefighting robot that is designed and "hardened" to be ideal for fires vs a slender, athletic, wide-hipped robot with highly flammable rubber padding in strategic places and a variety of special "attachments" that happen to include an appendage that can spray whipped cream or class B fire fighting foam.

I'd argue that the latter might be more appropriate for the home, not so good for a navy ship.

You'd also really like the AI to be pretty well debugged so that you don't get an inappropriate response if you mutter "Oh baby, I just burn for you..." at an inopportune moment.

rgb

Because they already have that, and it is boring? Because robotics are cool and fundable even where they are pointless and useless? Because the people that approved it have watched too many WW II movies? Because automated fire suppression systems might be vulnerable to damage elsewhere, requiring some system capable of dynamically bypassing nearly arbitrary intermediate zones of damage by archaic means like "fire hoses" in order to deliver fire suppression? Maybe a bit of all of these?

One can certainly imagine a scenario where a cruise missile or torpedo or even a shell strikes a ship in such a way that it knocks out most built in systems in some zone and sets that zone on fire, at which point sending humans in to fight the fire puts them at high risk and not sending humans in to fight the fire might put them at even greater risk from a sinking ship. At that point sending in a robot (humanoid or not) instead could be a lifesaver.

One is reminded of any number of science fiction stories, though, by Asimov and others. Building a humanoid robot for this purpose seems incredibly stupid. One doesn't want a robot to run a vacuum cleaner as if it is a metal version of a french maid. One wants a robot that is a vacuum cleaner, or a vacuum cleaner that happens to be a robot. Take vacuum cleaner. Add mechanism for moving. Add mechanism for navigating. Add minimal hardware needed to perform standard operational maintenance (that is, dump the dirt and clean filters). Add judgement/programming (or not, make it remote operated by humans sitting in a chair somewhere by remote control). In the end, one is more likely to end up with R2D2 with a carpet-sweeping vacuum base and "arms" that ARE extensible, manipulable tubes with nozzle(s) than with anything that looks like C3PO pushing a Dyson. And ditto for fire-fighting, only even more so.

rgb

OK, so we have multiple cosmi (space-time continua) embedded in a higher dimensional universe. I'm totally down with that and have written an entire SF novel based on the premise. Those cosmi (as the plural of cosmos) have a coupling. I'm good with that. But that means that "neighboring" cosmi will exist in a coherent bundle, and one will have to get quite distant from "this" brane to find a brane with substantial drift in its general mass distribution.

This is simple statistical mechanics, by the way -- if most brane-to-brane transitions occur in places where there is chuck of mass in one cosmos and none in another cosmos, there will be steady diffusion from the high mass concentration to the low one. This would lead to egregious and painful violation of mass-energy conservation as my foot in this cosmos diffuses into a vacuum in many, many others, because after all, the mass density of any cosmos at all is nearly zero with a hard, hard vacuum nearly everywhere.

This is overwhelming evidence that this sort of brane to brane, cosmos to cosmos transition does NOT happen in a universe in which the cosmi are equidistant and randomly organized. The only way that those transitions are possible at all is if there is a metric in the higher dimensional universe and if neighboring cosmi have ALMOST identical mass distributions and if transitions are only likely as pair exchanges between neighboring cosmi (note the requirement for pair exchanges is also a rather hard one or else one would observe a cumulative violation of conservation of mass in random-walk style that would be impossible to miss and that people have looked for, unless the transitions were VERY unlikely, or became very unlikely as a function of the intercosmos metric separation to increasingly different cosmi.

Note well that these constraints mean that no matter what, they aren't going to "bypass" a shield with a neutron flux, because there are going to be no nearby cosmi/branes in which the shield does not exist.

Note well in addition the response to those who suggest that this might be a way of viewing tunnelling. It is indeed -- the alternative cosmi are one of the POSSIBLE (I don't say plausible) interpretations of path integral formulations of quantum mechanics, integrated out. But in this case you STILL won't get tunneling through a barrier centimeters thick.

So this is a pointless experiment. One might as well just look for egregious violations of mass-energy conservation in everyday experiments, because if there is any substantive probability of mass energy departing our own spacetime cosmos and appearing in another "nearby" one, it would happen all the time and all mass concentrations would diffuse out into a multicosmo heat death.

Gravitation is an excellent possibility as the coupling between branes/cosmi -- one would guess that the "dimpling" of one spacetime dimples all of the neighboring ones on all sides (however many "sides" there are:-). The dimples probably don't have to precisely correspond, but they are likely to have to approximately correspond to minimize almost any sort of coupling across the sheets that permits a transition to occur in the first place.

rgb

In that part of the universe that is visible. We have no idea how much of the universe is beyond the ~14 billion light year visible boundary, only that it very likely extends at least many times as far beyond.

We absolutely do not know if there are more non-simply connected, non-interacting universes, because by definition you can't get there from here and cannot see them in any way -- but that does not mean that they do not exist, nor does it mean that they do. It means that we do not know if they exist because we have no evidence for their existence. We absolutely do not know if there are more coupled universes -- universes that one might be able to reach -- with independent space-time, because whatever coupling there might be between them, it is weak.

Finally, we do not know even in the simplest case that the many worlds quantum theorists hypothesize whether or not the bundle of universes is coherent, so that there are indeed lots of "nearby" universes with alternate-me as part of a coherent quantum bundle of me embedded in a coherent quantum bundle of universes that is semi-classical in evolution but knit together (entangled) with many little quantum jumps at the planck scale, or if you prefer the macroscopic cosmological hypothesis (which is pretty much completely without empirical foundation or any likelihood of obtaining any) of universes bubbling up in some sort of overarching ether with coupling constants that vary (without any explanation of how they might vary, or what sort of space of possible values bounds or does not boud the variation, or the physics that couples them with meta-coupling constants -- do you get the feeling that this is just mathematical science fiction, because it is -- we do not have any evidence that one single one more of these hypothetical universes exist.

It's like planets. Before 1990 there were lots of theories for planetary formation, and science fiction writers had been writing stories involving planets around other stars, usually with highly evolved life, just taking it for granted that they exist. But nobody had ever seen one, so that the statement "there is a planet within 100 LY of Earth with highly evolved life" was at best a scientific hypothesis unsupported by any evidence, but really was a complex form of science fiction because science had no way of sensibly bounding the probability that such a statement is true and there are a near-infinity of possibly true statements and we quite rightly give little credence to almost all of them without evidence and a really, really good reason to think that they might be true in the physics.

Today we have built instrumentation that permits us to "see" these "alternate universes" -- very crudely, but even that is improving over time as we build still-better instrumentation -- and we have at least some idea of what the density of planets of at least a certain size is in our immediate vicinity, much as we built the Hertzsprung-Russell diagram from parallax observations of nearby stars. We therefore have some small empirical basis for a model of planetary density around third generation stars (that probably doesn't extend into specialized environments, e.g. globular clusters). At the same time we are learning, somewhat painfully, lots of things about planetary chemistry and planetary ecology from observations within our own solar system and MIGHT -- as soon as we can sensibly measure some of the gross signatures of these things with even BETTER instrumentation -- soon get an idea of whether or not it is at all probable that there be highly evolved life within 100 LY. By an idea, of course I mean some statement of probability based on observations that has some statistical significance, as opposed to a statement built on top of a teetering tower of Bayesian priors 2/3 of which have no observational basis at all, none of which can be improved by recomputation of posterior probabilities based on observations within some restricted set.

A single example might be oceans -- we do not know for certain what the origin(s) of Earth's ocean might be. There are different hypotheses, and not sufficiently sensitive way of choosing between them this far after the event because we cannot look back at time and measure the probability of e.g. water-bearing comet impacts in the critical period after it cooled enough to hold an atmosphere -- plus there is the further complication of the probable impact that produced the moon. As a consequence, we have no good way of determining the probability of there being an ocean on any rocky planet in the right size range that might be orbiting any of the stars within 100 LY. It could be that such an ocean is a nearly absolute requirement for the evolution of advanced life forms -- it isn't even improbable that it is. It could be that only planets with molten iron cores (and hence magnetic fields, near-orbit moons formed via collision like ours was and a sufficient density of water-bearing comets will have the right "mix" of atmosphere regenerating oceans plus tidal stripping of stuff like ammonia and methane plus protection from radiation needed to allow the nucleation and growth of life (and we don't have any data on just how probably the latter is anyway).

As a consequence, while observations of nearby large planets has made it far more probable that there are planets the size of the Earth as well, and hence has systematically increased the probability of a life-bearing planet within 100 LY, that probability (as a statement of our ignorance, not of reality where there either is or there isn't) is still too uncertain to take any estimate of it seriously -- the error bars add up to "still science fiction", not scientific knowledge.

To cite a slightly different kind of example, consider magnetic monopoles. Now I personally just love the idea of monopoles. I teach electrodynamics at all levels and anything with the name "Dirac" attached should be taken very seriously indeed. Physicists in general would love for monopoles to exist, I think, because it would complete the symmetry of Maxwell's Equations and explain the quantization of charge, and it would have a profound impact on the development of quantum theories of everything as well, as now one has to fork the theories at the point where one decides "monopoles or no monopoles" and the latter requires some fancy dancing to explain charge quantization and WHY Maxwell's equations have a broken symmetry. Really, another broken symmetry as there would still remain the +/- charge asymmetry to explain, but there might be a way to get a twofer if there are monopoles.

Sadly, so far there is no reproducible, accepted evidence for the existence of magnetic monopoles, so in spite of the many physical theories they would improve, in spite of the enormous compulsion to believe in them as a sort of Platonic Ideal extension of our existing theory, all the physicists I know are very careful to draw the proper scientific box around them and present them as an unproven hypothesis -- in this case a notch up from science fiction, as they have immediate explanatory power of widespread observations -- not as a known (very probably true) "fact" supported by direct observation.

That's what annoyed me about the top article. It is sloppy, headline-grabbing stuff, not science. Science has a clear empirical foundation that is simply missing, but they aren't providing the required disclaimer. If I wrote a scientific paper that proved that Santa's Little Elves (if they exist) dine on dark matter (if it exists) and fart dark energy (if it exists) it wouldn't matter how valid and elegant the mathematics of the proof were, until somebody puts salt on the tail of an Elf, some dark matter, and some dark energy. And there's the rub, because they are all, well, dark. I might as well assert that the universe is run by invisible fairies. Prove me wrong! Kinda hard, because they are invisible.

So are alternate universes, to us, so far.

rgb

We know no such thing. We make conditional inferences, and part of what they are conditional on is our incomplete understanding of field theory. We don't even know if there is truly dark matter and/or dark energy, or what they are or how they work. Our understanding of the big bang/inflation extends back (again, rather conditionally since any number of field theory variations would completely alter it) to 13.8 bya but is extremely fuzzy given that we can't "see" events any earlier than the end of the Great Dark. All we have is a lower bound on the size of the Universe associated with the homogeneity of the CMB and estimates (which vary according to one's beliefs concerning DM/DE) as to whether the visible part of the universe is open or closed.

That's at the macroscopic level. At the microscopic level we are many orders of magnitude short of the Planck scale and do not even know how to reconcile quantum theory and gravity. But don't let that stop you from asserting certain knowledge just because you read something somewhere that was stated as truth without bothering to add all of the conditionals.

rgb

Unless they exist in a loop. Then there is no first. Then one can scale the loop up to infinity.

There are many rooms in Hilbert's Grand Hotel, and even though nobody ever brings cigars in through the front door, there is always a fresh cigar waiting in your room every morning.

Unless and until there is a glitch in the matrix, there isn't any really good reason to think we are a simulation in some sort of meta-universe, and some excellent information-theoretic reasons to think that we aren't. The estimates of "probability" here are completely meaningless because the Bayesian priors are utterly disconnected from any possibility of proof. If this, that, and the other thing are all true, then we are probably a simulation. If there are multiple universes at all (whatever that even means) and if we make a small mountain of assumptions about the rules that govern them (all unprovable) then there is no you in any of them, unless of course the distribution of universes isn't uniform or defies the odds and there is. If wishes were horses, beggars would ride. If pigs had wings, they could fly.

The only sad thing is that people are even pretending that this is science. You have it pegged -- it is science fantasy written by a cynical but very funny philosopher to mock human frailty when it comes to making absurd arguments without evidence.

    rgb

Why is it that they don't understand the meaning of the term "evidence" applied to "all the Universes that inflation creates" as if we actually have evidence that it creates more than a single one?

Seriously.

a) We have no evidence that even one "parallel universe" exists.

b) If "parallel universes" do exist, we don't really know what that means or what the overarching physical laws are that govern them, their distribution, their number because -- wait for it -- we have no evidence that even one parallel universe exists.

c) So somebody makes up a theory that takes an interpretation of quantum mechanics (which does exist, or at least for which there is actual evidence), extends it by fiat to describe one particular possible way that -- subject to a mountain of unprovable assumptions -- parallel universes might exist, and assumes that we know enough to be able to do the quantum statistical mechanics of the multiverse and determine whether or not they are infinite in number and whether the infinity is aleph null or aleph prime or whatever, and then makes a pronouncement that they cannot possibly justify because (oh my gosh) we have no evidence that even one parallel universe exists and hence we have no observational basis for determining their statistical distribution or the statistical distribution of some meta-universal dynamics .

Once upon a time science actually was based on observations. Well, actually, once upon a time it was all Platonic Forms, bullshit philosophy, but then the human race supposedly grew up just a little bit during the Enlightenment. Apparently we are now taking a giant step for mankind -- backwards.

Next stop, the Star Wars universe and the Tolkein universe. I'm not in them, but they sure are fun to read about as fiction, pending a glitch in the matrix...

rgb

Actually, you can kill yourself with a single 9 V battery -- or the 12 V battery of your car. One man did:

http://darwinawards.com/darwin...

The computation goes as follows. The issue, as several people have pointed out, is that it is current across the heart that causes defibrillation (basically interrupting the heart's natural rhythm so that it pulses chaotically), not a matter of cooking the person (which will also work, BTW, but isn't the most common cause of electrical shock deaths). It isn't even the case that more current is always worse -- there appears to be a range of currents that are more toxic than others. A brief explanation of this is here:

https://www.physics.ohio-state...

The maximally toxic range of currents across the thorax is empirically 0.1 to 0.2 amps. Below that it isn't enough to defibrillate, above that the heart muscle clamps all the way which means that when the current is removed it is actually more likely that it can with help or will on its own restore a normal rhythm.

The internal resistance of the human body once you introduce probes through the comparatively insulating skin is around 100 ohms. A 9V battery across ~100 ohms makes a thoracic current of roughly 0.1 amp, right at the start of the maximally fatal range. The Darwin above was given because an idiot didn't believe this and stuck probes through his skin to "prove" that it wasn't so.

Personally I've experienced shocks from 12 V car batteries when screwing around with them on rainy nights with salt water on my hands. That's another good way of reducing skin resistance. I didn't take the hit across the torso, but it was every bit as painful as a 110V shock through dry skin -- more so, actually -- and caused my muscles to contract like lightning.

None of this is actually news -- it has been known as long as there has been electricity, because people have been killing themselves accidentally with electricity just that long. My scout leader 50 years ago worked for GE (as an inventor, actually -- one of the people who invented the photodiode controlled light). He taught me that long ago to ground one finger and then brush another finger of the same hand against any possible hot wire so that you find out with a jolt across your hand, not through your torso. Hand to foot, hand to hand, not so good. People used to kill themselves all the time touching hot electrical switches while standing in wet feet on bathroom floors before ground fault circuits were invented and mandated by code.

None of which has much to do with TFA, but it is good to know if you work at all with electricity. Physicists need to know it just to be able to teach it to their students so THEY don't kill themselves accidentally one day. It isn't the voltage that kills you, it's the current, and it doesn't take much current to do the job (or much voltage to create a fatal current).