The Periodic Table isn't a model, or at least not a functional model. It's a chart - a way to represent data.
It's more than a chart. A table is not just a way to represent data; a simple list of all items in random order can represent the data just as well as a table can. A table is a way to organize data -- by spotting patterns, identifying which patterns are most important, then arranging the items to highlight those patterns. By choosing which patterns are important, you are implicitly constructing a model of what the items in the table are.
The Mendeleev-derived periodic table has done quite nicely for us: it predicted the properties of many elements long before we actually isolated them, and it was doing so well before we understood that the patterns highlighted by the table (the table's implicit model) were ultimately caused by the arrangement of electrons into quantum-mechanical energy-level shells by way of Pauli exclusion, with the arrangement of elements in each row directly dependent on the quantized degrees of freedom in each shell's energy level (hence the 2*[1], 2*[1+3], 2*[1+3+5], 2*[1+3+5+7] pattern in the table's row widths). Think of the table as a quick first-order approximation to the deeper equations needed to compute the true physics, such as the energy of a filled d-orbital in the third electron shell. A more complex table with an extra dimension or two of symmetry might be able to capture more patterns, giving us a more detailed model that produces better, more subtle approximations than the Mendeleev-derived model can yield; yet that new model would still bypass the tough work of calculating how electrons actually behave when packed around a single nucleus. (Or perhaps we could capture some symmetry affecting how an atom forms molecular bonds, or a nucleon symmetry that gives better predictions of stability and half-life or that better captures why the stable proton:neutron ratio isn't a perfectly smooth curve.)
Lies. There's nothing wrong with X that can be attributed to the protocol. It's the Xorg codebase that's gotten unwieldy. Wayland throws the baby out with the bathwater.
This is, of course, why XCB has taken the Linux universe by storm and everyone has abandoned toolkits like GTK in favor of the unicorns and puppies that XCB brings us. Everyone loves atoms, pixmaps, and server-side bitmap fonts.
You could drop a chair from an airplane and see... marvel at that incredible force that is gravity, see how it easily defeats that feeble electromagnetic force, and turns what was once a chair into a pile of splinters, and in due time-- they will make their way into the earth...
What's holding up the plane in the first place, giving the chair the potential energy to shatter on the ground below? Oh, right, the electrostatic repulsion of the electrons in the air pushing against the electrons in the plane's wing.
Seriously, though: gravity is 10,000,000,000,000,000,000,000,000,000,000,000,000 times weaker than the electromagnetic force.
Electromagnetic attraction also decays by a great amount over any significant distance...
Both decay 1/d^2, but the chair is electrically neutral (or very close to it), while the Earth is pulling against you with the full might of 10^24 kg of gravitational charge. Because the chair is neutral, it can only hold you up with the residual electromagnetic force, i.e. the fact that electrons and protons aren't evenly smeared throughout the atom's interior, and that's an incredibly weak effect compared to the actual electromagnetic force.
(This, by the way, is why the Electric Universe cranks inhabiting Slashdot are so off-base. Do they really think nobody would notice the un-subtle effects of a force 10^37 times more powerful than gravity?)
Instead, it can take a few swings around the black hole in a rapidly decaying orbit, until it slingshots out on a hyperbolic path. The smaller the black hole gets, the more definite the position is for every matter/antimatter particle pair, and by Heisenberg's uncertainty principle applied to position-momentum, this makes it easier for one of the two particles to escape.
Erm, that's not how orbital/slingshot mechanics work. In fact, a mass-bearing particle (from a virtual pair) could never escape a stationary black hole, because it wouldn't have enough energy to do so, and normal orbital mechanics wouldn't increase its energy.
Instead, you'd need a rotating black hole with an ergosphere. This is a weird area where space-time is dragged along the black hole faster than the speed of light relative to outer space. Here it is possible to extract energy from the black hole with what is called the Penrose process, and thus the electrons/positrons may gain enough speed to escape.
I was simplifying things for the audience, and wasn't even remotely about to bring up frame dragging. That said, I'm an interested layman who's never taken a physics class touching GR so correct me if I'm totally off-base, but I'm pretty sure that Hawking's conclusion was initially solved for Schwarzschild black holes, and if so the ergosphere around Kerr black holes clearly doesn't come into it. The region between the photon sphere and the event horizon has no stable orbits, but wouldn't there still be some trajectories that would send a particle out past the photon sphere? (On a more circuitous path than a straight line, I mean.) And the Wikipedia article for the photon sphere says that "[a]ny orbit that crosses [the photon sphere] from the inside escapes to infinity".
I will admit to never having plugged numbers into a tensor equation in my life, so I could be totally bullshitting here.
Then why would the particle be affected differently than the antiparticle? Why wouldn't *both* fall into the black hole equally?
Both the particle and the antiparticle are affected equally by gravity, but gravity is the weakest force in nature. Think about it: a simple chair, held together by the electromagnetic force, supports you above the ground by counteracting the gravitational attraction of the entire Earth pulling you down.
Since virtual particle pairs start from vacuum, they are always created with equal but opposite momentum. This momentum can't be very big because the attraction between the pair (usually electromagnetic) has to be strong enough to quickly counteract that initial momentum (and bring the particles back together fast enough for them to still count as "virtual"). But just because the momentum can't be very big doesn't mean it can't be big enough for one particle to escape a black hole, if the particles happen to pop into existence with one of them pointing in just the right direction to escape. Hawking predicts that the odds are 50/50 on whether it's the matter particle or the antimatter particle that does the escaping; it has nothing to do with the particles responding differently to gravity.
(Keep in mind that the escaping particle doesn't have to rocket out in a straight line at escape velocity. Instead, it can take a few swings around the black hole in a rapidly decaying orbit, until it slingshots out on a hyperbolic path. The smaller the black hole gets, the more definite the position is for every matter/antimatter particle pair, and by Heisenberg's uncertainty principle applied to position-momentum, this makes it easier for one of the two particles to escape. A smaller black hole also has the bonus that, looking out from just above the event horizon, more directions point away from the black hole, giving more chances to escape.)
You could actually make a black hole that radiates away Hawking radiation with a bias toward antimatter over matter, or vice versa. It's easy: black holes can have an electric charge, so just electrically charge the black hole! Like charges repel, so if the black hole is positively charged, it will preferentially eject positrons instead of electrons. However, the absorbed electrons neutralize the black hole's electric charge, bringing it back to neutral and making the Hawking radiation return to a 50/50 ratio between matter and antimatter.
(We suspect that the universe has a small preference for matter over antimatter, and this is why the universe is made of matter. But this mostly happens for some heavy uncharged mesons, not for lightweight simple particles like electrons. Here, "heavy" means "high energy" means "unlikely to appear in Hawking radiation". So the radiation may not strictly be 50/50, but it should be very close.)
One year (summer of '98?) the cicadas emerged in such numbers that they refused to stop singing at night. A wall of sound, blaring like a siren 24 hours a day, so loud you couldn't escape it indoors. After the first 50 kills on the front porch, my cats didn't know what to do with themselves. Tibicen is an annual genus, so I can only assume that the previous year's generation had simply been... busy.
So? they are genetically male.
self identification is bullshit. You don't go changing definition because it suits you. It's left over pop psychology form the 70s.
It's OK if you want to surgically change you gender, I don't care about that. but don't go around changing terms and definitions.
What does "genetically male" mean? 46,XY? Congratulations, you just excluded men with 47,XXY (Klinefelter syndrome) and 47,XYY (XYY syndrome) as "not male". Presence of a Y chromosome? Congratulations, women with 46,XY who lack the SRY gene (Swyer syndrome) are now "male". Presence of the SRY gene? Congratulations, 46,XY women with SRY but non-functional testosterone receptors (CAIS, complete androgen insensitivity syndrome) are now "male". And those are merely some of the conditions that are diagnosed by hormones and genitalia, without even looking at the giant ball of complexity that is the brain.
Self-identification of gender isn't bullshit 70's pop psychology. It's a practical consideration: science doesn't currently know what triggers male versus female identity in the brain. We know there's a surge of prenatal testosterone in the male fetus, followed by another testosterone surge a few weeks after birth, and that these two surges seem to trigger changes in the brain, but beyond that... hell if we know. We don't even know to what degree male identity is controlled by those testosterone surges versus direct action of SRY, or how many specific biological components there are in the brain that need to be affected. We don't know which circuits in the brain control self-identity ("I am a man/woman") versus proprioception ("my mental body map expects to receive sense data from male/female genitals") versus presentation ("other people see my behavior as feminine/masculine") versus orientation ("I am attracted to women/men"), if there are other categories than the ones I listed, where the lines are between these categories, or how blurry those lines are. Given how stable they are, we can infer that they're hardwired, which means that they must be phenotypes set during development; yet, the easiest way for a doctor to find out how genotype became phenotype in any particular patient is for the doctor to ask that patient to say their own gender identity.
Is it really "privacy" I'm guarding if I try to keep secrets from (a) a non-sentient computer program that (b) will never pass those secrets along to another human being (or even another non-sentient computer program at another company)?
Yes, you can flip a "developer mode" switch to disable the hardware lockdown
Does the developer mode switch also disable the warranty on the hardware? If I have flipped the developer mode switch, and the power connector wears out, am I out the full cost of replacement?
I suppose it's up to the manufacturer, but I'd be very surprised if anyone did. The ChromeOS firmware is designed so that, if you flip the switch back out of developer mode, it prompts you to confirm that it's going to wipe the disk and that you need to provide it with a signed OS image to install. The whole idea of the dev-mode switch is that, no matter what you've done to a ChromeOS device software-wise, you can always get it back to a pristine state. (AIUI, the firmware itself cannot be overwritten by the OS or the user, even in developer mode.)
Disclaimer: I work at Google but not on ChromeOS, Chrome, or anything remotely related to that, so I have no particular insider knowledge of it. I am the owner of an Acer AC700 Chromebook, however, purchased of my own free will. (I did boot the thing into developer mode once, out of curiosity, then I put it back.)
I could do it; I just worry about whether I'd be able to get hardware problems fixed under the manufacturer's warranty after having done it.
I suppose a manufacturer could go by different rules, but ChromeOS is specced to the manufacturers such that there's no way to brick it so bad you can't reimage back to the pristine signed-boot OS. (Unlike the OS, the bootloader isn't user-replaceable AIUI.) And the hardware is really not that different from a PC. It would be roughly equivalent to a PC maker refusing to honor your hardware warranty because you booted a Linux LiveCD once. Stranger things have happened, I suppose, but I would expect such a manufacturer to lose in court.
Disclaimer: I work at Google but not on ChromeOS, Chrome, or anything remotely related to that, so I have no particular insider knowledge of it. I am the owner of an Acer AC700 Chromebook, however, purchased of my own free will. (Principal complaint: the AC700 was sloooow. But it ran Netflix... so long as you weren't hoping to go fullscreen without stutter. Oh, and the built-in SSH terminal blew chunks; the new Secure Shell app is still rough but far better.)
I like firefox though. They tell you you are SOL without the passkey. I have no idea how Chrome encrypts. It looks like it is linked to your google account. Google could easily be holding all the keys.
Chrome uses a passphrase to encrypt sync data. By default it will use your Google account password, but you can change it to use any passphrase. If the Chrome devs are doing it right, they should be running the passphrase through PBKDF2 to derive an AES symmetric key. It's worth noting, though, that the Dashboard for "Chrome sync" shows counts for the number of synced items of each type. Assuming they're doing the crypto correctly, I see only two ways the Dashboard could know those numbers: (a) if Chome sends the counts in plaintext as part of the sync, or (b) if the items are individually encrypted (which is generally a bad idea due to known plaintext).
I do know from personal experience that you're SOL if you lose the Chrome sync passphrase (or if you simply want to change it). You have to click the "Stop sync and delete data from Google" link in the Dashboard, wait 5 or 10 minutes for the delete to finish, then set up sync again for all your Chrome instances. Oh, and Chrome sync still doesn't support OAuth login, so setting up sync is a pain if you have 2-factor auth set up on your account (as you should).
Disclaimer: I happen to work at Google, but I don't interact with Chrome except as a user. I'm using knowledge gleaned only from using Chrome sync with my personal account.
BTW 80k to start in SF seems pretty horrible considering the cost of living there [...]
No, that's actually not bad. Online cost of living calculators don't grok SF. When I moved to SF 5 years ago for a tech job I started out on $75k/year, and I did fine for myself living solo. Sure, you're probably going to drop an extra $15k-$20k/year on rent -- I moved into a ~650ft 1BR apartment for $2100/month, a bit of a premium for a good neighborhood -- but Craigslist is booming with roommate offers, and most other living expenses are about the same as other cities. Utilities are less (milder weather), eating out is more (higher wages, trendier places), groceries are the same. Entertainment is less (lots of free/cheap shows) but there's more of it, so you may wind up spending more.
Beyond rent, the only other thing that's noticeably more expensive than elsewhere is car ownership; parking garage fees of $300/month aren't uncommon if you work downtown and expect to park there every day, and there's the perennial delight of California gas prices if you're moving from out of state. But even before costing out the parking surprise, a $65/month Muni "M" pass is hella cheaper than gas + insurance + maintenance for owning your own car anyway. Throw in a ~$4/month ZipCar annual membership (partially or fully subsidized by some employers) and you can still have access to a car when transit won't cut it; the rental itself runs about $12/hour, which includes the cost of gas, insurance, and all the maintenance headaches. Even without an employer subsidy, that annual ZipCar fee is 1/3 the price of a WoW subscription, i.e. totally worth it at $75k/year.
[...] If you read the word Bayesian in this sentence, you know for certain that you did. There is nothing probabilistic about it. [...]
Not quite. You've never had the experience of remembering having done something, then having someone contradict you, then asking around and finding out that your memory is faulty? If you were certain of your memory, no finite amount of evidence would ever convince you that you were mistaken. Your example instead demonstrates that we pick the most probable (most "familiar") explanation without conscious consideration of alternatives, and we only backtrack to alternatives when the first explanation is sufficiently falsified to demote it from the best explanation.
That's not to say that this has any bearing on Judea Pearl's research into causal networks. Causal networks complement a probabilistic approach, as each causal node operates on purely Bayesian principles; the only difference is the added operation of graph surgery to represent counterfactuals. It's certainly true that the naïve extension of Bayesian probability to a decision theory (Evidential Decision Theory) is silly -- it results in "Speeding on the way to work is correlated with being late to work, therefore if I don't speed I can't be late!", and it's also true that causal graphs naïvely extend to a decision theory (Causal Decision Theory) that fixes the most egregious silliness. But Bayesian probability is still a key piece of CDT, and even CDT doesn't fix everything (look up Newcomb's paradox).
This is just an example of a MaCHO. We've theorized about them for a while. They are a strong candidate for a bulk of the dark matter we've detected. The other candidates are WIMPs.
Uh, no. MaCHOs were supposed to be Jupiter-size to brown dwarf-size lumps of mass, careening through galaxies without being associated with stars or other luminous matter. A black hole *can* count as a MaCHO *if* it has no accretion disk, but we think most black holes have accretion disks and therefore emit X-rays (and thus don't count as dark matter). This black hole is firmly in the not-a-MaCHO category; for that matter, what we today know about Big Bang baryogenesis pretty strongly rules out MaCHOs being the dominant type of dark matter, so they've mostly fallen by the wayside in modern cosmological thinking.
If the microwave radiation is strong enough, it definitely is going to cause skin damage (and also a bit below the skin), by simply boiling the tissue.
Believe me, that's a risk I worry about every day. But I recently discovered that there are other frequencies that can cause such damage! I now refuse to allow my family within a mile of any restaurant with so-called "heat lamps" (or as I prefer, "death lamps"), and I'm seriously considering banning from my household anything that emits between 400 and 790 THz. I heard one of my neighbors actually bought an Easy-Bake Oven for their kids. An Easy-Bake Oven! Won't somebody please think of the children?
(Seriously, though, if you pour significantly more than a kilowatt per meter square of EM into living tissue, you're gonna have a bad time. There are a handful of cases, e.g. VHF, where you might be able to bump that figure by an order of magnitude (maaaybe two) because humans are reasonably transparent at those frequencies. But as a rule of thumb, all non-ionizing EM from visible light down cooks you the same way.)
If the 5th packet was lost, in standard TCP you'd need to retransmit packets 5-10. With this encoding, you could in theory transmit only 1 packet to complete the set, regardless of which was lost, based on how the new ACKs describe the algebraic degrees of freedom remaining in solving for the original packet bytes. That means that you put out 11 packets instead of 15 packets into the same noisy environment, and the existing TCP window controls perceive less losses.
Uhh, that sounds like an extremely convoluted reinvention of TCP SACK (RFC 2018) using some knockoff of Reed-Solomon instead of, y'know, "I got packets 1-4 and 6-10, please retransmit #5".
The scheme you describe is a Message Authentication Code, not a salted hash. If you use a salted hash when you actually need a MAC, you're potentially compromising your system's security.
Not that I'm a pro or anything, but junk DNA was anything that didn't encode proteins, right?
No, that's "non-coding DNA". The Ars Technica article has a very nice Venn diagram. In short, we infer that most non-coding DNA is junk DNA because it shows signs of neutral drift (i.e. it doesn't matter to reproductive fitness), but non-coding DNA is different from junk DNA, and regulatory DNA is always non-coding but can be either junk or non-junk.
Some concrete examples (with Venn diagram colors in parens):
Coding DNA that isn't junk (white): a gene.
Coding DNA that is junk (blue): an endogenous retrovirus.
Regulatory non-coding DNA that isn't junk (orange/yellow): a promoter for a gene.
Regulatory non-coding DNA that is junk (orange/yellow/blue): a promoter for a pseudogene.
Non-regulatory non-coding DNA that isn't junk (yellow): hmm... an intron, I guess.
Non-regulatory non-coding DNA that is junk (yellow/blue): the letters "CGG" 30 times in a row on the X chromosome. (See aside below for more info.)
(Terminology: a "pseudogene" is a gene damaged so badly by frame shifts or early stop codons that it can't code for protein anymore. Before they break and become pseudogenes, they're often duplicates of some existing gene, which is why breaking them can be fitness-neutral. DNA transposons and sloppy cross-overs in meiosis make gene duplication reasonably common. Gene duplication is important for evolution as well: duplicated genes are free to mutate in random directions until they stumble on a new useful function, with the original free to keep the old one. For instance, the vertebrate blood clotting cascade was clearly formed from several rounds of dupe-then-mutate, and similarly with the huge family of myosin muscle proteins.)
(Terminology: an "intron" is a stretch of DNA that gets snipped out of the resulting RNA before the RNA can code for protein. It's not quite junk: an intron has recognition signals that say "please cut RNA here", and IIRC the intron needs to have roughly the correct length, but most of the intron is arbitrary nonsense. Some genes have alternative splices, where the same gene can code for different proteins by swapping in different coding regions -- "exons" -- like lego bricks. Alternative splices are important in the immune system, for instance: they're how antibodies work. And the alternative splicing stuff wouldn't be possible without introns, including the nonsense filler that helpfully spaces out the exons so the splice enzymes can operate correctly.)
(Aside: long sequences of repetitive DNA can trip up the DNA polymerase enzyme that copies DNA, causing the stretch of DNA to lengthen itself in the next generation... and the longer it gets, the better the chance is that DNA polymerase will screw up and make it longer still. The...CGG-CGG-CGG... sequence I mentioned has about 30 repeats in healthy individuals; but if the number of repeats climbs high enough, it causes Fragile X syndrome. Apparently the nucleus tries to silence the repeat by attaching methyl groups (CH3), which is standard procedure in the nucleus for turning off misbehaving DNA, but methylation isn't terribly precise and a nearby promoter happens to live nearby. This promoter is responsible for a nearby gene that's important in brain development; if the promoter is silenced by methylation, the reduced gene expression causes a form of severe autism.)
As PZ Myers asks, if the remaining 40% is all functional... why do onions need ten times as much as humans need,
When you question them, this is all the "Junk DNA" proponents' arguments ever boil down to: "I don't understand it, therefore it's junk."
We DO understand what 60% of the genome is doing. 45% of it is parasitic. Do you really think that LINEs, parasitic DNA strands that make copies of themselves over and over again, are NOT junk?
and why can the fugu pufferfish thrive without any of it?
Thrive....under what conditions? And what is your definition of "thrive"? Have you subjected the animal to every possible condition it could ever experience in life, to completely ensure that the DNA in question can never be triggered under any circumstances?
Of course you haven't--because you haven't the foggiest clue how it all even works. "Junk DNA", like many other idiocies in the long history of science, is the legacy of morons.
Fugu "thrive" in the sense that they're alive and reproducing. Fugu are not dying off. Fugu are not endangered. Fugu are not at an evolutionary dead end suffering under a genetic legacy that's handicapping them, like pandas or the various all-female species of parthenogenic whiptail lizard are. Like I said, thriving. The only thing that threatens them at all: their tasty lip-numbing tetrodotoxin convinces humans to turn them into sushi.
Why do fugu (390 megabases) get by with 3.5 times less DNA than zebrafish (1.4 gigabases)? Why do fruit flies eliminate non-coding "junk" DNA from their genome 40 times faster than crickets do? (And, for that matter, why do both fruit flies AND crickets AND most eukaryotes excise DNA from their genome at all?) Why does the common onion, Allium cepa (15876 megabases), need 2.3 times more DNA than its close relative the Blue Spear chive, Allium altyncolicum (6860 megabases)? Does bear's garlic, Allium ursinum (30870 megabases), have extra DNA stashed away in preparation for a future alien invasion that will sap the precious bodily fluids from lesser garlics? No. If two closely related Allium species both live in the same area, and look similar, and taste similar, and their cells have a similar appearance under a microscope, and they are equally prolific in their environment... but one has twice as much DNA as the other... then by definition at least half of the larger wad of DNA must be redundant. Maybe not inert, but "junk" in the sense of duplicate or obsolete functionality that doesn't need to be there to grow a successful, sexually mature plant that can compete in the real world.
In short, "junk DNA" is basically a shorthand for "DNA that could be deleted from all individuals in a species without harming the reproductive fitness of those individuals". By this standard, LOTS of DNA is junk -- at least the part that's known to be parasitic (45% of the human genome), and probably a lot more.
Are there regions of non-coding DNA, in the 40% of the human genome as yet not understood by humanity, that confer a benefit to their hosts? Almost certainly. But as a percentage of the genome, the 80% claim in the ENCODE press release is f***ing ridiculous. As best as I can tell, the ENCODE papers are using a shotgun approach that would categorize known parasites like LINEs, ERVs, and transposons as "functional". In one sense, such DNA is not passively sitting there, so it's not "junk" in the sense of being "inert". But for all the spinning of its little wheels, it's doing nothing to help you survive. Sure sounds like junk to me.
Beyond that... fine, call me a moron if you like, but PZ Myers is a Ph.D. professor of biology who studies genetics. This is his area of expertise, and his day job is to teach this stuff to people. If you don't have a Ph.D. i
Slashdot Mirror
It's more than a chart. A table is not just a way to represent data; a simple list of all items in random order can represent the data just as well as a table can. A table is a way to organize data -- by spotting patterns, identifying which patterns are most important, then arranging the items to highlight those patterns. By choosing which patterns are important, you are implicitly constructing a model of what the items in the table are.
The Mendeleev-derived periodic table has done quite nicely for us: it predicted the properties of many elements long before we actually isolated them, and it was doing so well before we understood that the patterns highlighted by the table (the table's implicit model) were ultimately caused by the arrangement of electrons into quantum-mechanical energy-level shells by way of Pauli exclusion, with the arrangement of elements in each row directly dependent on the quantized degrees of freedom in each shell's energy level (hence the 2*[1], 2*[1+3], 2*[1+3+5], 2*[1+3+5+7] pattern in the table's row widths). Think of the table as a quick first-order approximation to the deeper equations needed to compute the true physics, such as the energy of a filled d-orbital in the third electron shell. A more complex table with an extra dimension or two of symmetry might be able to capture more patterns, giving us a more detailed model that produces better, more subtle approximations than the Mendeleev-derived model can yield; yet that new model would still bypass the tough work of calculating how electrons actually behave when packed around a single nucleus. (Or perhaps we could capture some symmetry affecting how an atom forms molecular bonds, or a nucleon symmetry that gives better predictions of stability and half-life or that better captures why the stable proton:neutron ratio isn't a perfectly smooth curve.)
... and, uh, "praise" is not the word to describe what my co-workers are saying about the movie.
Go read "What Colour are your bits?".
Lies. There's nothing wrong with X that can be attributed to the protocol. It's the Xorg codebase that's gotten unwieldy. Wayland throws the baby out with the bathwater.
This is, of course, why XCB has taken the Linux universe by storm and everyone has abandoned toolkits like GTK in favor of the unicorns and puppies that XCB brings us. Everyone loves atoms, pixmaps, and server-side bitmap fonts.
You could drop a chair from an airplane and see... marvel at that incredible force that is gravity, see how it easily defeats that feeble electromagnetic force, and turns what was once a chair into a pile of splinters, and in due time-- they will make their way into the earth...
What's holding up the plane in the first place, giving the chair the potential energy to shatter on the ground below? Oh, right, the electrostatic repulsion of the electrons in the air pushing against the electrons in the plane's wing.
Seriously, though: gravity is 10,000,000,000,000,000,000,000,000,000,000,000,000 times weaker than the electromagnetic force.
Electromagnetic attraction also decays by a great amount over any significant distance...
Both decay 1/d^2, but the chair is electrically neutral (or very close to it), while the Earth is pulling against you with the full might of 10^24 kg of gravitational charge. Because the chair is neutral, it can only hold you up with the residual electromagnetic force, i.e. the fact that electrons and protons aren't evenly smeared throughout the atom's interior, and that's an incredibly weak effect compared to the actual electromagnetic force.
(This, by the way, is why the Electric Universe cranks inhabiting Slashdot are so off-base. Do they really think nobody would notice the un-subtle effects of a force 10^37 times more powerful than gravity?)
Instead, it can take a few swings around the black hole in a rapidly decaying orbit, until it slingshots out on a hyperbolic path. The smaller the black hole gets, the more definite the position is for every matter/antimatter particle pair, and by Heisenberg's uncertainty principle applied to position-momentum, this makes it easier for one of the two particles to escape.
Erm, that's not how orbital/slingshot mechanics work. In fact, a mass-bearing particle (from a virtual pair) could never escape a stationary black hole, because it wouldn't have enough energy to do so, and normal orbital mechanics wouldn't increase its energy.
Instead, you'd need a rotating black hole with an ergosphere. This is a weird area where space-time is dragged along the black hole faster than the speed of light relative to outer space. Here it is possible to extract energy from the black hole with what is called the Penrose process, and thus the electrons/positrons may gain enough speed to escape.
I was simplifying things for the audience, and wasn't even remotely about to bring up frame dragging. That said, I'm an interested layman who's never taken a physics class touching GR so correct me if I'm totally off-base, but I'm pretty sure that Hawking's conclusion was initially solved for Schwarzschild black holes, and if so the ergosphere around Kerr black holes clearly doesn't come into it. The region between the photon sphere and the event horizon has no stable orbits, but wouldn't there still be some trajectories that would send a particle out past the photon sphere? (On a more circuitous path than a straight line, I mean.) And the Wikipedia article for the photon sphere says that "[a]ny orbit that crosses [the photon sphere] from the inside escapes to infinity".
I will admit to never having plugged numbers into a tensor equation in my life, so I could be totally bullshitting here.
Then why would the particle be affected differently than the antiparticle? Why wouldn't *both* fall into the black hole equally?
Both the particle and the antiparticle are affected equally by gravity, but gravity is the weakest force in nature. Think about it: a simple chair, held together by the electromagnetic force, supports you above the ground by counteracting the gravitational attraction of the entire Earth pulling you down.
Since virtual particle pairs start from vacuum, they are always created with equal but opposite momentum. This momentum can't be very big because the attraction between the pair (usually electromagnetic) has to be strong enough to quickly counteract that initial momentum (and bring the particles back together fast enough for them to still count as "virtual"). But just because the momentum can't be very big doesn't mean it can't be big enough for one particle to escape a black hole, if the particles happen to pop into existence with one of them pointing in just the right direction to escape. Hawking predicts that the odds are 50/50 on whether it's the matter particle or the antimatter particle that does the escaping; it has nothing to do with the particles responding differently to gravity.
(Keep in mind that the escaping particle doesn't have to rocket out in a straight line at escape velocity. Instead, it can take a few swings around the black hole in a rapidly decaying orbit, until it slingshots out on a hyperbolic path. The smaller the black hole gets, the more definite the position is for every matter/antimatter particle pair, and by Heisenberg's uncertainty principle applied to position-momentum, this makes it easier for one of the two particles to escape. A smaller black hole also has the bonus that, looking out from just above the event horizon, more directions point away from the black hole, giving more chances to escape.)
You could actually make a black hole that radiates away Hawking radiation with a bias toward antimatter over matter, or vice versa. It's easy: black holes can have an electric charge, so just electrically charge the black hole! Like charges repel, so if the black hole is positively charged, it will preferentially eject positrons instead of electrons. However, the absorbed electrons neutralize the black hole's electric charge, bringing it back to neutral and making the Hawking radiation return to a 50/50 ratio between matter and antimatter.
(We suspect that the universe has a small preference for matter over antimatter, and this is why the universe is made of matter. But this mostly happens for some heavy uncharged mesons, not for lightweight simple particles like electrons. Here, "heavy" means "high energy" means "unlikely to appear in Hawking radiation". So the radiation may not strictly be 50/50, but it should be very close.)
I grew up in the Wichita, Kansas area with Tibicen pruinosa. Here's a YouTube video of one singing.
One year (summer of '98?) the cicadas emerged in such numbers that they refused to stop singing at night. A wall of sound, blaring like a siren 24 hours a day, so loud you couldn't escape it indoors. After the first 50 kills on the front porch, my cats didn't know what to do with themselves. Tibicen is an annual genus, so I can only assume that the previous year's generation had simply been... busy.
So? they are genetically male. self identification is bullshit. You don't go changing definition because it suits you. It's left over pop psychology form the 70s. It's OK if you want to surgically change you gender, I don't care about that. but don't go around changing terms and definitions.
What does "genetically male" mean? 46,XY? Congratulations, you just excluded men with 47,XXY (Klinefelter syndrome) and 47,XYY (XYY syndrome) as "not male". Presence of a Y chromosome? Congratulations, women with 46,XY who lack the SRY gene (Swyer syndrome) are now "male". Presence of the SRY gene? Congratulations, 46,XY women with SRY but non-functional testosterone receptors (CAIS, complete androgen insensitivity syndrome) are now "male". And those are merely some of the conditions that are diagnosed by hormones and genitalia, without even looking at the giant ball of complexity that is the brain.
Self-identification of gender isn't bullshit 70's pop psychology. It's a practical consideration: science doesn't currently know what triggers male versus female identity in the brain. We know there's a surge of prenatal testosterone in the male fetus, followed by another testosterone surge a few weeks after birth, and that these two surges seem to trigger changes in the brain, but beyond that... hell if we know. We don't even know to what degree male identity is controlled by those testosterone surges versus direct action of SRY, or how many specific biological components there are in the brain that need to be affected. We don't know which circuits in the brain control self-identity ("I am a man/woman") versus proprioception ("my mental body map expects to receive sense data from male/female genitals") versus presentation ("other people see my behavior as feminine/masculine") versus orientation ("I am attracted to women/men"), if there are other categories than the ones I listed, where the lines are between these categories, or how blurry those lines are. Given how stable they are, we can infer that they're hardwired, which means that they must be phenotypes set during development; yet, the easiest way for a doctor to find out how genotype became phenotype in any particular patient is for the doctor to ask that patient to say their own gender identity.
The "input" you supply is your privacy.
Is it really "privacy" I'm guarding if I try to keep secrets from (a) a non-sentient computer program that (b) will never pass those secrets along to another human being (or even another non-sentient computer program at another company)?
GPS would work perfectly fine without relativity calculations. [...]
False and false. Relativity matters when you care about nanosecond timing.
Yes, you can flip a "developer mode" switch to disable the hardware lockdown
Does the developer mode switch also disable the warranty on the hardware? If I have flipped the developer mode switch, and the power connector wears out, am I out the full cost of replacement?
I suppose it's up to the manufacturer, but I'd be very surprised if anyone did. The ChromeOS firmware is designed so that, if you flip the switch back out of developer mode, it prompts you to confirm that it's going to wipe the disk and that you need to provide it with a signed OS image to install. The whole idea of the dev-mode switch is that, no matter what you've done to a ChromeOS device software-wise, you can always get it back to a pristine state. (AIUI, the firmware itself cannot be overwritten by the OS or the user, even in developer mode.)
Disclaimer: I work at Google but not on ChromeOS, Chrome, or anything remotely related to that, so I have no particular insider knowledge of it. I am the owner of an Acer AC700 Chromebook, however, purchased of my own free will. (I did boot the thing into developer mode once, out of curiosity, then I put it back.)
I could do it; I just worry about whether I'd be able to get hardware problems fixed under the manufacturer's warranty after having done it.
I suppose a manufacturer could go by different rules, but ChromeOS is specced to the manufacturers such that there's no way to brick it so bad you can't reimage back to the pristine signed-boot OS. (Unlike the OS, the bootloader isn't user-replaceable AIUI.) And the hardware is really not that different from a PC. It would be roughly equivalent to a PC maker refusing to honor your hardware warranty because you booted a Linux LiveCD once. Stranger things have happened, I suppose, but I would expect such a manufacturer to lose in court.
Disclaimer: I work at Google but not on ChromeOS, Chrome, or anything remotely related to that, so I have no particular insider knowledge of it. I am the owner of an Acer AC700 Chromebook, however, purchased of my own free will. (Principal complaint: the AC700 was sloooow. But it ran Netflix... so long as you weren't hoping to go fullscreen without stutter. Oh, and the built-in SSH terminal blew chunks; the new Secure Shell app is still rough but far better.)
I like firefox though. They tell you you are SOL without the passkey. I have no idea how Chrome encrypts. It looks like it is linked to your google account. Google could easily be holding all the keys.
Chrome uses a passphrase to encrypt sync data. By default it will use your Google account password, but you can change it to use any passphrase. If the Chrome devs are doing it right, they should be running the passphrase through PBKDF2 to derive an AES symmetric key. It's worth noting, though, that the Dashboard for "Chrome sync" shows counts for the number of synced items of each type. Assuming they're doing the crypto correctly, I see only two ways the Dashboard could know those numbers: (a) if Chome sends the counts in plaintext as part of the sync, or (b) if the items are individually encrypted (which is generally a bad idea due to known plaintext).
I do know from personal experience that you're SOL if you lose the Chrome sync passphrase (or if you simply want to change it). You have to click the "Stop sync and delete data from Google" link in the Dashboard, wait 5 or 10 minutes for the delete to finish, then set up sync again for all your Chrome instances. Oh, and Chrome sync still doesn't support OAuth login, so setting up sync is a pain if you have 2-factor auth set up on your account (as you should).
Disclaimer: I happen to work at Google, but I don't interact with Chrome except as a user. I'm using knowledge gleaned only from using Chrome sync with my personal account.
BTW 80k to start in SF seems pretty horrible considering the cost of living there [...]
No, that's actually not bad. Online cost of living calculators don't grok SF. When I moved to SF 5 years ago for a tech job I started out on $75k/year, and I did fine for myself living solo. Sure, you're probably going to drop an extra $15k-$20k/year on rent -- I moved into a ~650ft 1BR apartment for $2100/month, a bit of a premium for a good neighborhood -- but Craigslist is booming with roommate offers, and most other living expenses are about the same as other cities. Utilities are less (milder weather), eating out is more (higher wages, trendier places), groceries are the same. Entertainment is less (lots of free/cheap shows) but there's more of it, so you may wind up spending more.
Beyond rent, the only other thing that's noticeably more expensive than elsewhere is car ownership; parking garage fees of $300/month aren't uncommon if you work downtown and expect to park there every day, and there's the perennial delight of California gas prices if you're moving from out of state. But even before costing out the parking surprise, a $65/month Muni "M" pass is hella cheaper than gas + insurance + maintenance for owning your own car anyway. Throw in a ~$4/month ZipCar annual membership (partially or fully subsidized by some employers) and you can still have access to a car when transit won't cut it; the rental itself runs about $12/hour, which includes the cost of gas, insurance, and all the maintenance headaches. Even without an employer subsidy, that annual ZipCar fee is 1/3 the price of a WoW subscription, i.e. totally worth it at $75k/year.
[...] If you read the word Bayesian in this sentence, you know for certain that you did. There is nothing probabilistic about it. [...]
Not quite. You've never had the experience of remembering having done something, then having someone contradict you, then asking around and finding out that your memory is faulty? If you were certain of your memory, no finite amount of evidence would ever convince you that you were mistaken. Your example instead demonstrates that we pick the most probable (most "familiar") explanation without conscious consideration of alternatives, and we only backtrack to alternatives when the first explanation is sufficiently falsified to demote it from the best explanation.
That's not to say that this has any bearing on Judea Pearl's research into causal networks. Causal networks complement a probabilistic approach, as each causal node operates on purely Bayesian principles; the only difference is the added operation of graph surgery to represent counterfactuals. It's certainly true that the naïve extension of Bayesian probability to a decision theory (Evidential Decision Theory) is silly -- it results in "Speeding on the way to work is correlated with being late to work, therefore if I don't speed I can't be late!", and it's also true that causal graphs naïvely extend to a decision theory (Causal Decision Theory) that fixes the most egregious silliness. But Bayesian probability is still a key piece of CDT, and even CDT doesn't fix everything (look up Newcomb's paradox).
This is just an example of a MaCHO. We've theorized about them for a while. They are a strong candidate for a bulk of the dark matter we've detected. The other candidates are WIMPs.
Uh, no. MaCHOs were supposed to be Jupiter-size to brown dwarf-size lumps of mass, careening through galaxies without being associated with stars or other luminous matter. A black hole *can* count as a MaCHO *if* it has no accretion disk, but we think most black holes have accretion disks and therefore emit X-rays (and thus don't count as dark matter). This black hole is firmly in the not-a-MaCHO category; for that matter, what we today know about Big Bang baryogenesis pretty strongly rules out MaCHOs being the dominant type of dark matter, so they've mostly fallen by the wayside in modern cosmological thinking.
If the microwave radiation is strong enough, it definitely is going to cause skin damage (and also a bit below the skin), by simply boiling the tissue.
Believe me, that's a risk I worry about every day. But I recently discovered that there are other frequencies that can cause such damage! I now refuse to allow my family within a mile of any restaurant with so-called "heat lamps" (or as I prefer, "death lamps"), and I'm seriously considering banning from my household anything that emits between 400 and 790 THz. I heard one of my neighbors actually bought an Easy-Bake Oven for their kids. An Easy-Bake Oven! Won't somebody please think of the children?
(Seriously, though, if you pour significantly more than a kilowatt per meter square of EM into living tissue, you're gonna have a bad time. There are a handful of cases, e.g. VHF, where you might be able to bump that figure by an order of magnitude (maaaybe two) because humans are reasonably transparent at those frequencies. But as a rule of thumb, all non-ionizing EM from visible light down cooks you the same way.)
If the 5th packet was lost, in standard TCP you'd need to retransmit packets 5-10. With this encoding, you could in theory transmit only 1 packet to complete the set, regardless of which was lost, based on how the new ACKs describe the algebraic degrees of freedom remaining in solving for the original packet bytes. That means that you put out 11 packets instead of 15 packets into the same noisy environment, and the existing TCP window controls perceive less losses.
Uhh, that sounds like an extremely convoluted reinvention of TCP SACK (RFC 2018) using some knockoff of Reed-Solomon instead of, y'know, "I got packets 1-4 and 6-10, please retransmit #5".
The scheme you describe is a Message Authentication Code, not a salted hash. If you use a salted hash when you actually need a MAC, you're potentially compromising your system's security.
And why is that? Google would love to see Microsoft die.
You don't bring nukes to a knife fight. Sure, you win the knife fight, but now everyone else knows to nuke you first and ask questions later.
Not that I'm a pro or anything, but junk DNA was anything that didn't encode proteins, right?
No, that's "non-coding DNA". The Ars Technica article has a very nice Venn diagram. In short, we infer that most non-coding DNA is junk DNA because it shows signs of neutral drift (i.e. it doesn't matter to reproductive fitness), but non-coding DNA is different from junk DNA, and regulatory DNA is always non-coding but can be either junk or non-junk.
Some concrete examples (with Venn diagram colors in parens):
(Terminology: a "pseudogene" is a gene damaged so badly by frame shifts or early stop codons that it can't code for protein anymore. Before they break and become pseudogenes, they're often duplicates of some existing gene, which is why breaking them can be fitness-neutral. DNA transposons and sloppy cross-overs in meiosis make gene duplication reasonably common. Gene duplication is important for evolution as well: duplicated genes are free to mutate in random directions until they stumble on a new useful function, with the original free to keep the old one. For instance, the vertebrate blood clotting cascade was clearly formed from several rounds of dupe-then-mutate, and similarly with the huge family of myosin muscle proteins.)
(Terminology: an "intron" is a stretch of DNA that gets snipped out of the resulting RNA before the RNA can code for protein. It's not quite junk: an intron has recognition signals that say "please cut RNA here", and IIRC the intron needs to have roughly the correct length, but most of the intron is arbitrary nonsense. Some genes have alternative splices, where the same gene can code for different proteins by swapping in different coding regions -- "exons" -- like lego bricks. Alternative splices are important in the immune system, for instance: they're how antibodies work. And the alternative splicing stuff wouldn't be possible without introns, including the nonsense filler that helpfully spaces out the exons so the splice enzymes can operate correctly.)
(Aside: long sequences of repetitive DNA can trip up the DNA polymerase enzyme that copies DNA, causing the stretch of DNA to lengthen itself in the next generation... and the longer it gets, the better the chance is that DNA polymerase will screw up and make it longer still. The ...CGG-CGG-CGG... sequence I mentioned has about 30 repeats in healthy individuals; but if the number of repeats climbs high enough, it causes Fragile X syndrome. Apparently the nucleus tries to silence the repeat by attaching methyl groups (CH3), which is standard procedure in the nucleus for turning off misbehaving DNA, but methylation isn't terribly precise and a nearby promoter happens to live nearby. This promoter is responsible for a nearby gene that's important in brain development; if the promoter is silenced by methylation, the reduced gene expression causes a form of severe autism.)
What happens when they attempt to hand out the 1,000,000,001th SSN? Or do government officials somehow trump combinatorics?
SSNs are recycled. They're only unique among the living.
Er... I stand corrected: http://www.ssa.gov/history/hfaq.html Q20.
What happens when they attempt to hand out the 1,000,000,001th SSN? Or do government officials somehow trump combinatorics?
SSNs are recycled. They're only unique among the living.
As PZ Myers asks, if the remaining 40% is all functional... why do onions need ten times as much as humans need,
When you question them, this is all the "Junk DNA" proponents' arguments ever boil down to: "I don't understand it, therefore it's junk."
We DO understand what 60% of the genome is doing. 45% of it is parasitic. Do you really think that LINEs, parasitic DNA strands that make copies of themselves over and over again, are NOT junk?
and why can the fugu pufferfish thrive without any of it?
Thrive....under what conditions? And what is your definition of "thrive"? Have you subjected the animal to every possible condition it could ever experience in life, to completely ensure that the DNA in question can never be triggered under any circumstances?
Of course you haven't--because you haven't the foggiest clue how it all even works. "Junk DNA", like many other idiocies in the long history of science, is the legacy of morons.
Fugu "thrive" in the sense that they're alive and reproducing. Fugu are not dying off. Fugu are not endangered. Fugu are not at an evolutionary dead end suffering under a genetic legacy that's handicapping them, like pandas or the various all-female species of parthenogenic whiptail lizard are. Like I said, thriving. The only thing that threatens them at all: their tasty lip-numbing tetrodotoxin convinces humans to turn them into sushi.
Why do fugu (390 megabases) get by with 3.5 times less DNA than zebrafish (1.4 gigabases)? Why do fruit flies eliminate non-coding "junk" DNA from their genome 40 times faster than crickets do? (And, for that matter, why do both fruit flies AND crickets AND most eukaryotes excise DNA from their genome at all?) Why does the common onion, Allium cepa (15876 megabases), need 2.3 times more DNA than its close relative the Blue Spear chive, Allium altyncolicum (6860 megabases)? Does bear's garlic, Allium ursinum (30870 megabases), have extra DNA stashed away in preparation for a future alien invasion that will sap the precious bodily fluids from lesser garlics? No. If two closely related Allium species both live in the same area, and look similar, and taste similar, and their cells have a similar appearance under a microscope, and they are equally prolific in their environment... but one has twice as much DNA as the other... then by definition at least half of the larger wad of DNA must be redundant. Maybe not inert, but "junk" in the sense of duplicate or obsolete functionality that doesn't need to be there to grow a successful, sexually mature plant that can compete in the real world.
In short, "junk DNA" is basically a shorthand for "DNA that could be deleted from all individuals in a species without harming the reproductive fitness of those individuals". By this standard, LOTS of DNA is junk -- at least the part that's known to be parasitic (45% of the human genome), and probably a lot more.
Are there regions of non-coding DNA, in the 40% of the human genome as yet not understood by humanity, that confer a benefit to their hosts? Almost certainly. But as a percentage of the genome, the 80% claim in the ENCODE press release is f***ing ridiculous. As best as I can tell, the ENCODE papers are using a shotgun approach that would categorize known parasites like LINEs, ERVs, and transposons as "functional". In one sense, such DNA is not passively sitting there, so it's not "junk" in the sense of being "inert". But for all the spinning of its little wheels, it's doing nothing to help you survive. Sure sounds like junk to me.
Beyond that... fine, call me a moron if you like, but PZ Myers is a Ph.D. professor of biology who studies genetics. This is his area of expertise, and his day job is to teach this stuff to people. If you don't have a Ph.D. i