You can show from basic stellar structure theory that you need a minimum mass of.08 solar masses or so to ignite hydrogen on the p-p cycle. (You can burn heavier isotopes like lithium and deterium at lower masses, but these contribute negligibly to the energy budget of the star because of their low abundances.).08 solar masses is about 80 Jupiter masses, so this star is over the p-p burning limit. As another author pointed out, the star has a radius comparable to Jupiter. It turns out that due to the physics of degeneracy pressure. Jupiter is about at a maximum in radius for substellar objects.
There is an important point to clarify here regarding nomenclature.
Stars shine by nuclear fusion of hydrogen. That can only be sustained in stars of about.08 solar masses or greater.
However, smaller mass objects are formed alongside stars with lower mass still. Astronomers call objects with insufficient mass to burn lithium (but enough to burn deuterium) "brown dwarfs".
At still lower masses, objects which cannot even burn deuterium are labelled (somewhat arbitrarily) according to their environment. If they are orbiting around another star, they are called planets. If they are free-floating, they are given another name -- free-floating objects or planets, depending on the author.
In the end, this is all a rather arbitrary scheme imposed by humans. For instance, if an object not burning deuturium is ejected from a protostellar disk, it gets changed from a planet to a free-floater in the process!
This article deals not with mass but with radius. There are in fact many objects which are known to exist with far less mass than the star reported here. They are not called "stars," but in fact the distinction is just one of nomenclature.
Does anyone else see something fundamentally wrong with that?
No, not in the least. Your question itself suggests a profound misunderstanding of what it means to conduct research.
The private sector has one objective, and that is to make a profit. Some will conduct limited research, but only because they view it as a means to an end. The problem is, of course, that basic research which would be overlooked by companies with a short-term view often pay off tremendously more in the long run.
Take a classic example. In the mid-19th century, industry was busy at work at improving intercontinental communications. How? By running cables underneath the Atlantic ocean. At the same time, James Clerk Maxwell scribbled and bibbled a few equations which suggested a completely different answer -- using long wavelength light waves, which hithertofore no one had even conceived of. The result? Radio, television, and (with the work of a few more scribblers doing quantum mechanics in the 1920s) the modern electronics industry.
The point is that no company would have ever invested in the basic research which gave rise to those industries. Only governments can devote the level of resources to basic research that are really needed to advance our knowledge.
Note that is not to say that private foundations (RIM's new Perimter institute, Keck, etc.) cannot have an impact. But they are only a drop in the bucket.
As other posters have mentioned, interactive fiction has thrived in an online community connected by usenet groups, webpages, and annual contests since the disappearance of Infocom. A few people have attempted commercial programs, but there does not appear to be much of a market for them, particularly when you can obtain Infocom-quality games or even better for free. If you are curious, take a look at this website.
With regard to the graphical versus non-graphical issue, one should point out that the medium only carries the message. Graphics games have all of the same problems of story-telling and entertainment, but must devote such a huge amount of effort to depicting everything graphically that very little effort is devoted to the depth of gameplay in general.
Speaking of game development, here is one of my thought-provoking usenet posts from over ten years ago on the issue of NPCs. Evidently someone else thought it was thought-provoking as well, as it had been excised and stored on someone's website this entire time. The context was interactive fiction, but you can easily see that the same underlying ideas can be applied to graphical games as well.
From: bobf@piglet (Robert Taylor Fisher)
Subject: Use of Utility Functions in Interactive Fiction
Date: 20 Apr 92 19:29:23 GMT
Early attempts at simulation of characters in Interactive Fiction relied
upon the use of "scripts." Each script was painstakingly written for each
character, taking into account what the player might actions the player might
perform. Take, for instance, Mrs. Robner in Infocom's Deadline. After
opening the door for the player, she would state something, and head off to
eat breakfast. However, nothing the player could do could change her course
of action. Thus, while the script method produced lifelike, believable action,
it did so at the cost of flexibility.
An alternative method relies upon the use of "utility functions," which
are commonly seen in economics and game theory. The basic concept is very
simple. Let x1 and x2 be two choices which a person has available to him. Also y
function U(x) in such a way that if the person is rational, U(x1) > U(x2).
The actual values assigned are arbitrary so long as they retain the order
of the preferences. This concept is easily extended to any number of options
{xn}.
Usign utility functions, one can design characters with built-in
preferences which will determine that character's actions. To make things
more realistic, one can also make the utility functions dependent upon time
so that characters will tend to be more dynamic. As an easy example, take
the simulation of hunger. If the current time is t and the character last
ate at time to, then we could simulate the character's need for food as
a utility function which is proportional to the amount (t - to). One could
make the function's value inversely proportional to the size of the
character's last meal, c. Thus, the form of the utility function for
acquiring food would be like U(eating)~ 1/c * (t - to). This is just an
arbitrary example -- better forms for the function could probably be
chosen. If one were to compile dozens of these functions, each of which
depends on time, the program would take the character and evaluate
the functions, determining which option has the highest value, and then
enable the character to carry out that action.
The form of the function may also have some conditional dependence. For
instance, suppose we had an option for striking the player. The function may
have a clause reading (if player strikes me) then add X to function. In this
way, the characters would take into account how the player interacts with them,
and react accordingly. Perhaps most excitingly, the characters can also be
allowed to interact among each other using slight alterations to this scheme,
possibly having extremely subtle effects on their interactions with the player.
All that would be necessary would be to to r
The plan to decomission Hubble earlier this year came within days of the Bush plan to redirect NASA to explore Mars. If you really believe that the decision was based on good science and engineering, and not on political goals, then you are incredibly naive. The announcement came with only a nominal budgetary increase, so many NASA budgets were completely slashed, including the Hubble servicing mission. Several other very important missions, including the Dark Energy Probe, are now on permanent ice as well. It is not a matter of "expense," as you suggest, but rather one of priority. We have the money, but rather than devoting it to science, it is now going into the drain of a Mars mission which will never launch, because Congress will never approve the hundreds of billions required.
The NGST (now named Webb) telescope has been in the works for years. It has a launch date of 2010. The Hubble reservicing mission was planned for 2006, and should have kept Hubble in operation until at least 2011 or 2012. That WAS a rational plan to keep the HST maintained, and to ensure than we have one optical space observatory in service at all times.
I agree that efficiency can save us factors of several, but there is one major issue which you have neglected -- that of the rise of the third world. Most of the world's population resides in underdeveoped nations, which are currently using very little power. As these nations become more developed, their energy consumption rates will skyrocket, just as ours did during the 19th and 20th centuries.
I am not certain how this got ranked to 5, but it is a common misconception, so allow me to clarify.
When all the stars burn out, space will start collapsing again as energy falls into black holes.
No. This is not how gravity, according to general relativity, works. The curvature of spacetime is, roughly speaking, proportional to its local mass/energy content. In fact, converting things into black holes doesn't change the curvature of spacetime to any substantial degree once you are more than a few Schwarzschild radii away -- Newtonian gravity works just fine in the far-field region. Therefore, as massive stars die out and form black holes, their gravitational field is not substantially affected far from them.
Incidentally, the vast majority of stars will not form black holes, but rather white dwarfs. Just so that you know.;-)
We often toss out a question to the Astronomy 1 students tests their knowledge of this principles. What would happen to the Earth's orbit if the sun could be suddenly replaced by a black hole? Most students answer that the Earth would fall in. (Wrongo! Too many scifi movies.) Answer : the orbit is practically unchanged.
I'm a computational astrophysicist, so my main tools are computers.;-)
But more generally, computers are nearly universally present in all scientific settings. Observers no longer gaze through the eyepiece of a telescope; they sit in a control room in front of a computer. (Observers who use Hubble, Chandra, or Spitzer, of course, never leave their computer in their office.) Similarly, few experiments generate reams of paper rolls of data anymore; almost all experimetnalists use a computer in some fashion to generate and analyze their results.
All of this begs the question... if in nearly any scientific setting you have a high-powered computer sitting right in front of you on your desk, why on Earth would you choose to use a hand-held calculator instead?
I agree that calculators are still useful for educational settings, although for a different reason that the one you suggest.
As a computational astrophysicist, I no longer find any use for hand-held calculators whatsoever. If I find the need to do a detailed numerical computation while working, I simply pop up Mathematica. I have hundreds of physical constants relevant for my work stored in a handy ".m" file, so if I wish to compute, say, the Planck mass, I can simply type in "Sqrt [hbar c / G]", rather than punching in numerical values. It is far more convenient and _more powerful_ than using a hand calculator since I can readily construct expressions, do symbolic manipulations on them, and produce complex plots with very little effort. Mathematica has an enormous understanding of mathematical functions, so if I want, say, the value of second derivative of the Laguerre polynomial of order n, I can simply enter "N [D [LaguerreL [n, x], x] ]". (Try to stuff than in your calculator and smoke it.) It also has unlimited numerical precision, so if I want the value of Pi to 100 digits, I just enter "N [Pi, 100]". (Not a practical example, given that 100 decades is greater than the total number of fundamental particles in the current Hubble radius, but an illustrative one nonetheless.) In addition, I have the ability to immediately translate those expressions into Tex format or C or Fortran code, so that they can be readily incorporated into papers or other standalone code. And that is saying nothing of the fact that a full-sized keyboard is vastly easier to use than _either_ a stylus or a weeny calculator keypad.
If I am in a meeting of some kind or just informally speaking to someone, and the need for a quick numerical estimate comes up, I can always whip out an estimate good to within 10% without using any calculating aid other than a pencil and paper. You'll find that all good scientists and engineers can do quick back-of-the-envelope calculations when the need arises.
So what use are calculators in schools when students could be using Mathematica (or any other mathematical software of their choice) on their laptops? The plain fact of the matter is that math and science instructors almost universally do not wish to construct a course in which the learning goes beyond the simplest applications of the principles learned. Therefore, they must almost always artificially control additional information and calculating aids during exams (normally no notes, books, or computers). Calculators are the one concession they do allow, only because their functionality is limited, and therefore the aid they provide is also limited. I admit calculators have become reasonably sophisticated as of late, and so as a result, partially to offset any potential unfair advantage, instructors are increasingly allowing students to stuff all of the equations they can fit onto a "cheat sheet" of a certain size.
When you think about the situation, it is fairly ludicrous. No literature professor would make a student write a term paper on Shakespeare without having access to the original plays and all the additional supplemental information he can lay his hands on. But it is easier to construct a system in which students are tested on rote memory and simple application of known template examples from class, rather than being able to use all the resources at their disposal to synthesize everything they have learned in creative applications. Synthesis and creative use of one's knowledge, is, after all, what real world science and engineering are all about. Primarily because of this artificial construction, classwork performance is quite often a poor indicator of a student's potential as a real scientist or engineer.
You have some good points, but there is one key distinction you are missing.
There IS certainly innovation among all those categories (books, films, music, etc.), but the VAST MAJORITY of the innovation is usually being made on a very small scale, with just a handful of talented individuals working on the edge. Movies are a great example. Blair Witch was not produced by a Hollywood theatre, nor are the dozens of indie films snatched up by Hollywood distributors at Sundance and other film festivals. They are made by a few people, almost always on a shoestring budget (often funded on someone's credit cards!). A number of these films are made with astonishingly low budgets... El Mariachi was done on $10K, and many not much more than that. The same goes for books (where just a single person working in their spare hours can produce the next classic), music, and zines.
Now... back to the game industry. What can anyone do with $10K these days? That would hardly be enough money to purchase one high-end workstation with Maya and other requisite software tools. You see, people are EXPECTING highly polished graphics and gameplay out of each new video game. Long gone are the days where a single Russian program can whip out Tetris in a few weeks of effort, and create a sensation. I'm sure that thousands of slashdotters have tremendous ideas for awesome games, and many of them have the programming skills to pull it off. But if they are to to compete with the current big-name titles, they have to play by their rules. Who will do the artwork? The motion capturing and animation? The original music score? The voice-overs? The analogy to films would be like if the movie-going audience demanded to see Return of the King-quality battles and special effects in EVERY film they see. If that were the case, then the indie film industry would be dead as a doornail too.
There is room for innovation here (think of games like Snood) but the game-going audience needs to lose their addiction to big-name licenses and fancy production values and focus on the one thing that gaming is about : fun.
Your point is well-taken. Stated simply, in your view, contextual phrases should be ranked according to usage.
But how are we to weigh the usage? Is every hit on every webpage of equal statistical relevance -- whether it is the New York Times or a random blogger?
The obvious answer is that, no, if one wants a meaningful search, some sites are more statistically relevant and should be weighted as such.
But if they are to be weighted, how? Does the NYT carry 10, 10^3, 10^6 times the relevance of a blogger? This factor is tied in in some fashion to how many sites link back to the site in question. But it can be washed out if a sufficiently large number of low-relevance sites are included. Hence we have phenomena such as Google bombing.
Although right now these effects are of "zero measure" (in Google's claim), I think the problem is continuously increasing, as people become aware of how Google operates, and can influence searches. For instance, it is easily conceivable to me that the first 10-20 searches of a third party political candidate could be swamped out by a highly devoted Google bombing on the part of his political rivals. That would be a serious misrepresentation of information, with potentially huge impact on the rest of us.
Google's page summary is giving out misleading information about him, and they refuse to do anything about it.
Have you even looked at the California Board website in question? At the very top of the page, there is a huge honking disclaimer that reads:
"This list contains names of licensees for which accusations have been filed and are pending possible disciplinary action." (emphasis mine)
The crux of what this CPA is claiming in his case is that this information about a pending case against him is difficult to find on the CBA website, but it pops up immediately when you Google him. He believes this is how Google is "misrepresenting" the information.
No one is disputing the factuality of the information -- only the manner in which it is presented. No matter how you look at it, the CBA website should be responsible for the factual content, since they are putting the information out for the world to see. If the information should not be up yet, or it is not 100% accurate in every regard -- fine, but then the CBA should be responsible. If it is a matter of public record -- fine, but then why is this CPA bitch complaining?
Forget Tom Clancy. There is a much better story from the Cold War, and it is all true.
Shortly after WWII, the United States decided that it should monitor dust particulates in the upper atmosphere to test for the possibility of an above-ground test by Soviets. The program itself was highly contoversial; Oppenheimer (falsely) thought the radioactive material would go into the atmosphere in a gaseous phase, and diffuse away so rapidly that it would never be detected. This turned out to be incorrect because a significant amount of radioactive material enters into solid particulates, which can float in long-lived clouds hanging in the upper atmosphere for weeks or months. Cold War generations knew this phenomenon as a terrifying, bone-chilling household word : fallout.
Still others in the military (noteable General Groves) smugly thought that it would take the Soviets decades to catch up, and hence there was no rush in setting up a detection system.
Much to everyone's shock and surprise, a scant few weeks after the program was initiated, positive results came back from the chemical analysis of the upper-atmosphere dust gathered on one mission. Hans Bethe and other experts were called in to interpret the findings. Not only could they determine the yield of the blast, but they could also infer the date (and hence, approximately, from prevelant winds, the location) of the blast, and even the composition and design of the device.
The implications were clear. Someone had filched the US design from the Manhattan Project, and the Soviets had the information. The seeds of the Cold War and McCarthyism were sown.
The most amazing twist to this story is that if the US had delayed its fallout survaillance program by just a few months, the Cold War would have been delayed by years -- until the Soviets tested their next device. That is not to say that there would never have been a Cold War. But the US would have lived on in its smug complacency for years longer, and McCarthyism as we know it today wouldn't have occurred as it did at that time. History might have turned out quite differently indeed...
If you find this story fascinating, you would get a kick out of reading "Dark Sun," which contains this en
To answer the poster's question, clearly none of this is new. The point of the article is that much of the vigilance and expertise was allowed to dissipate after the Cold War ended. Now, post-9/11, the incentives for due dilligence are back...
I think this IBM device is the most innovative idea I've seen in "mobile" computing since the iPod. Basically, one carries around the CPU and hard drive of your computer, and docks it wherever you need to use it -- at home, at the office, in a mobile dock. It's the notion of a dock/laptop combination taken to its logical extreme. Plus, with some basic software installed, there would be no need for a separate portable media player ala iPod. It may very well revolutionize our way of thinking about computing.
The question becomes even more convolved once we move outside the solar system, since we now know of a wide diversity of systems, of which our own solar system is only one particular instance. (And perhaps not even typical at that.) We know that there are objects extending all the way down from massive stars (around 100 Msun) to hydrogen-burning stars like our sun to brown dwarfs to planets. Clearly any definition of a planet must apply not only to our solar system, but also to these extrasolar systems. Some of these systems are much like our own (for instance, they may contain a brown dwarf orbiting a star, or a planet orbiting a star), and some (including a few systems of low enough mass to qualify as a planet) are "free-floaters" -- just sitting out there by themselves in space.
I think ultimately the question is whether there is a single continuous "initial mass function" of isolated objects or not. The best idea as to how stars acquire their initial mass is that turbulence in the interstellar medium, which exists on all scales, establishes a power-law distribution of initial masses. Every once in a while, you get a very strong shock which passes by inside a giant molecular cloud and forces the collapse of a large region which then goes on to form a massive star. But more typically, you form stars more like our sun. And just as rare as massive collapses are very small mass ones which go on to form isolated brown dwarfs and free-floating planets. If this model holds up to be true, then we are all mincing words in our definitions of isolated systems, since they are all manifestations of the same universal formation process.
However, to avoid the difficult question of formation mechanisms, an IAU working group of some of the most respected people in the field established a working definition to define by fiat what it means to be a brown dwarf, and a planet. Extrasolar "planets" are those objects orbiting a star which are beneath the deteurium-burning limit -- regardless of how they are formed. "Brown dwarfs" are defined to be those which burn deuterium but not lithium, and "sub-brown dwarfs" (NOT free-floating planets!) are defined to be those isolated objects which do not burn deuterium. Even the working group itself admitted that this definition was not satisfying to a single member of the group, and so it is likely it will be replaced at a later time with something more physically-motivated. The "planet/planetismal/KBO" distinction was pushed back to our own solar system, since it will be some time before anyone sees anything that small in another system.
Also of interest is the following link, which gives a history of previous claims for additional planetary members of our solar system :
SEDS.
Actually, the VLA has pretty much been in its current configuration for almost 25 years : see this historical note for some of its amazing history. The reason why you probably saw only five dishes is that the array can be operated in different modes. Depending on whether an astronomer wants a highly zoomed-in, extremely high-resolution image, or a wider field of view with lower resolution, he can instruct the telescope operators to move the array dishes either closer or father (respectively) on their tracks. Its one of the most basic tricks of radio interferometry. Sometimes even a single dish is used to repeat an observation of a highly resolved region at the same frequency; although the single dish cannot match the resolution of the array, it _can_ detect the total power emitted, and therefore determine how much the high-resolution observation "missed".
You're absolutely right that we don't hear as much about radio astronomonical observations. There are probably a few reasons. The first stems from the fact that astronomers tend to specialize in a given waveband -- the knowledge and expertise that is required to observe in the optical is very different from that required to observe in the radio, and both are in turn radically different from that required to observe in gamma rays. A few exceptionally talented astronomers operate in a couple of bands, but almost none operate across the entire spectrum. Radio astronomers are a minority within the astronomical community, and while they do really great science, it is primarily on sources filled with cold gas or electrons gyrating in the magnetic field, and are somewhat more difficult to popularize than a snazzy Hubble photo. The other reason, I think, is largely cultural and political. NASA does a great job pushing its science (Hubble, Chandra, Spitzer, planetary missions) to the public's attention, and devotes a lot of its effort culling the media's attention. The remainder of the astronomical community, including the national radio and optical observatories, tends to be much more conservative, and does not make much of an effort to garner attention. Generally you will only hear of their work when the press appears at one of the American Astronomical Soceity (AAS) and snatches up a few of their stories to splash up in their papers and broadcasts.
This parent posting was really great, and I applaud the moderators who modded it up. However, sadly, it was the ONLY reasonable post modded at 5 -- the rest are just a bunch of idiots making stupid comments which some other idiot found funny. Posters and moderators should definitely try harder to keep postings on topic and technically worthy. That is, after all, what slashdot is all about.
This comment is bang-on. The author's comments are insightful. So insightful, in fact, that, amazingly enough, NASA has already gathered such a review committee. They do so once a decade, in a huge effort that takes input from the entire astronomy/astrophysics/space sciences/planetary sciences community. It is often referred to as the "Decadal Review" or the "Decadal Survey," and features some of the most respected scientists in the community. (For instance, the 2000 survey was sponsored by Princeton's binary pulsar discoverer and Nobel Laureate Joe Taylor and the University of California at Berkeley Physics Department Chairman, Chris McKee.) Rather than having dozens of warring factions fighting for a limited pool of funding, it has long been realized that it is far better for everyone to get together and decide on the basis of scientific progress which goals should be given the highest priority. Then, when NASA goes to congress to ask for the billions it will take to fund these missions, the entire scientific community stands behind NASA as one.
The result? There were many goals described, some of which may now be in peril as a result of Bush's backhanded hit on science within NASA. Putting a man on the moon or on Mars is not on the list, however. You can read the brief summary here. The entire text of the report is availbale here. Although the entire text is well over 200 pages, there is a lot of material in it that sets it apart from most beauracratic reports, including some 40+ pages of a layman's discussion of the science driving the requests.
Bob
Re:It's like Netscape v. Microsoft in that...
on
Google v. Microsoft
·
· Score: 5, Interesting
I like the way you give both possible angles into the competition.
However, there is one ace card in Microsoft's back pocket which you left out : Microsoft's Theory Group. MS supports a very high-powered discrete math and computer science group, comparable to that of a top-notch university. It's not just deep pockets here : it's a long-term commitment to building up a substantial research group pursuing fundamental research on problems closely allied to various technical issues. Noteably, this includes web searches, which is really just a problem in graph theory.
One needs to be extremely cautious in comparing the relative maturity of two technologies. The IE/NS analogy shows that MS can rapidly catch up to an existing technology, since they can afford to outspend and outlast any competitor. The only survival strategy is to evolve more rapidly than MS can follow; NS failed in that game by version 4, and it has only been relatively recently that other browsers (noteable Mozilla and Safari) have posed serious competition to the now-stagnant IE. Based on the existing high-powered theory already within MS, I am willing to bet that not only will MS have caught up to Google within 1-2 years, but they very well may also proceed to blow right past them.
You're thinking of CYC, as in enCYClpedia. (The open source version of this system was released in the wake of the movie AI, and is available at opencyc.org. )
As another poster has pointed out, this project had nothing to do with heuristics, and everything to do with ontology -- that is, the formal specification of knowledge using logical constructs.
In the way of background, the project was the brainchild of Douglas Lenat, who proposed to take traditional AI technques to their limit by giving a computer program all of the knowledge of the world which a toddler might have. Once a computer (so his reasoning went) had that knowledge, it could then be fed additional facts, and it would be able to understand them as well, with some occasional guidance from humans (much as a toddler might). Eventually the program would have enough knowledge that The project took dozens of computer scientists and philosophers specalizing in ontology the better part of the 1990s, and was frequently covered in the popular press.
The end result had not been so widely discussed or covered. I infer the program was not in fact self-propagating as was intended. Clips I saw towards the end of the project showed the enormous potential problems in this approach. For instance, one might tell CYC about a electric shaver. Later that night, it would go through and find inconsistencies between this new knowledge and its existing ontological database. For instance, in the case of the electric shaver, it might ask whether the human was also an electrical appliance while using the shaver, because someone had previously specified a rule that anything incorporating an electrical appliance was itself an electrical appliance. Hence, I gather that rather becoming self-propagating, the larger the ontological database became, the greater the number of logical inconsistences that arose, thereby miring the entire approach. At some point, progress would presumably be bottlenecked by the fact that many ontological experts trained in the CYC software would have to be working around the clock to attempt to sort out these problems.
Is anyone aware of any software projects that actually use CYC or openCYC? I am also greatly interested if anyone has a link to a good discussion by Lenat or others on their assessment of the CYC project at its completion. It is a monumental chapter in the history of AI, but despite this, I have never seen many technical articles published by CYC team members. I suspect that it may be nearly impossible to have a fully self-consistent set of ontological definitions of the world in the manner that CYC attempted. If so, that would be an amazing statement about AI, and indeed, the nature of knowledge itself.
I totally agree with you. NASA is an enormous enterprise, and although the manned spaceflight missions get most of the attention (and budget), the unmanned missions and satellites and hard astrophysics funded by NASA make a vastly more significant science impact. This is coming from someone who got his graduate research supported by a generous NASA fellowship under the GSRP program.
Just the great observatories program alone -- Compton, Hubble, Chandra, and now Spitzer -- each constructed and launched with roughly $1 B, underline the point that when TENS of billions of dollars get shifted around, science could very well be left out in the cold.
Moreover, the THEORY portion of NASA's science is peanuts of the overall science program, which is itself peanuts of the overall NASA budget. Each year, over a hundred PIs go all out to fight for the few million dollars provided by NASA's Astrophysics Theory Program (ATP). About a dozen are actually funded, to the tune of about $100 K each. The irony is that after all those tens of billions of dollars are spent on launching people on top of firecrackers and designing and building telescopes and satellites, only a miniscule amount is devoted towards our physical understanding of those observations.
I totally agree. I read about this poster several months ago when it first appeared as a preprint on the astro-ph preprint server. I loved it so much that I printed out the postscript version to put on the door of my office at work.
Almost any technically-minded person who stops to look at it finds it very cool, and often has questions about it. The mark of its usefulness as a teaching tool is the fact that many cool astronomical facts can be picked up simply by carefully looking at it. For instance, there is an enormous gap in the Sloan Digital Sky Survey galaxies when plotted on this map. At first you may think it is simply an artifact, but actually it occcurs where we are trying to peer through the center of the galaxy -- the so-called "zone of avoidance". It shows up on the plot because the data are plotted in galactic coordinates. The plot is rich in such detail. A few more are mentioned in the astro-ph paper; truly curious and interested folks would benefit from reading it.
Slashdot Mirror
You can show from basic stellar structure theory that you need a minimum mass of .08 solar masses or so to ignite hydrogen on the p-p cycle. (You can burn heavier isotopes like lithium and deterium at lower masses, but these contribute negligibly to the energy budget of the star because of their low abundances.) .08 solar masses is about 80 Jupiter masses, so this star is over the p-p burning limit. As another author pointed out, the star has a radius comparable to Jupiter. It turns out that due to the physics of degeneracy pressure. Jupiter is about at a maximum in radius for substellar objects.
There is an important point to clarify here regarding nomenclature.
.08 solar masses or greater.
Stars shine by nuclear fusion of hydrogen. That can only be sustained in stars of about
However, smaller mass objects are formed alongside stars with lower mass still. Astronomers call objects with insufficient mass to burn lithium (but enough to burn deuterium) "brown dwarfs".
At still lower masses, objects which cannot even burn deuterium are labelled (somewhat arbitrarily) according to their environment. If they are orbiting around another star, they are called planets. If they are free-floating, they are given another name -- free-floating objects or planets, depending on the author.
In the end, this is all a rather arbitrary scheme imposed by humans. For instance, if an object not burning deuturium is ejected from a protostellar disk, it gets changed from a planet to a free-floater in the process!
This article deals not with mass but with radius. There are in fact many objects which are known to exist with far less mass than the star reported here. They are not called "stars," but in fact the distinction is just one of nomenclature.
Does anyone else see something fundamentally wrong with that?
No, not in the least. Your question itself suggests a profound misunderstanding of what it means to conduct research.
The private sector has one objective, and that is to make a profit. Some will conduct limited research, but only because they view it as a means to an end. The problem is, of course, that basic research which would be overlooked by companies with a short-term view often pay off tremendously more in the long run.
Take a classic example. In the mid-19th century, industry was busy at work at improving intercontinental communications. How? By running cables underneath the Atlantic ocean. At the same time, James Clerk Maxwell scribbled and bibbled a few equations which suggested a completely different answer -- using long wavelength light waves, which hithertofore no one had even conceived of. The result? Radio, television, and (with the work of a few more scribblers doing quantum mechanics in the 1920s) the modern electronics industry.
The point is that no company would have ever invested in the basic research which gave rise to those industries. Only governments can devote the level of resources to basic research that are really needed to advance our knowledge.
Note that is not to say that private foundations (RIM's new Perimter institute, Keck, etc.) cannot have an impact. But they are only a drop in the bucket.
== bob
With regard to the graphical versus non-graphical issue, one should point out that the medium only carries the message. Graphics games have all of the same problems of story-telling and entertainment, but must devote such a huge amount of effort to depicting everything graphically that very little effort is devoted to the depth of gameplay in general.
Speaking of game development, here is one of my thought-provoking usenet posts from over ten years ago on the issue of NPCs. Evidently someone else thought it was thought-provoking as well, as it had been excised and stored on someone's website this entire time. The context was interactive fiction, but you can easily see that the same underlying ideas can be applied to graphical games as well.
From: bobf@piglet (Robert Taylor Fisher)
Subject: Use of Utility Functions in Interactive Fiction
Date: 20 Apr 92 19:29:23 GMT
Early attempts at simulation of characters in Interactive Fiction relied upon the use of "scripts." Each script was painstakingly written for each character, taking into account what the player might actions the player might perform. Take, for instance, Mrs. Robner in Infocom's Deadline. After opening the door for the player, she would state something, and head off to eat breakfast. However, nothing the player could do could change her course of action. Thus, while the script method produced lifelike, believable action, it did so at the cost of flexibility.
An alternative method relies upon the use of "utility functions," which are commonly seen in economics and game theory. The basic concept is very simple. Let x1 and x2 be two choices which a person has available to him. Also y function U(x) in such a way that if the person is rational, U(x1) > U(x2). The actual values assigned are arbitrary so long as they retain the order of the preferences. This concept is easily extended to any number of options {xn}.
Usign utility functions, one can design characters with built-in preferences which will determine that character's actions. To make things more realistic, one can also make the utility functions dependent upon time so that characters will tend to be more dynamic. As an easy example, take the simulation of hunger. If the current time is t and the character last ate at time to, then we could simulate the character's need for food as a utility function which is proportional to the amount (t - to). One could make the function's value inversely proportional to the size of the character's last meal, c. Thus, the form of the utility function for acquiring food would be like U(eating)~ 1/c * (t - to). This is just an arbitrary example -- better forms for the function could probably be chosen. If one were to compile dozens of these functions, each of which depends on time, the program would take the character and evaluate the functions, determining which option has the highest value, and then enable the character to carry out that action.
The form of the function may also have some conditional dependence. For instance, suppose we had an option for striking the player. The function may have a clause reading (if player strikes me) then add X to function. In this way, the characters would take into account how the player interacts with them, and react accordingly. Perhaps most excitingly, the characters can also be allowed to interact among each other using slight alterations to this scheme, possibly having extremely subtle effects on their interactions with the player. All that would be necessary would be to to r
I hate to disagree, but that is not what Nobel organization says. They claim Marconi's radio patents were the first in the world.
--astr
I think you are missing out on one major fact.
The plan to decomission Hubble earlier this year came within days of the Bush plan to redirect NASA to explore Mars. If you really believe that the decision was based on good science and engineering, and not on political goals, then you are incredibly naive. The announcement came with only a nominal budgetary increase, so many NASA budgets were completely slashed, including the Hubble servicing mission. Several other very important missions, including the Dark Energy Probe, are now on permanent ice as well. It is not a matter of "expense," as you suggest, but rather one of priority. We have the money, but rather than devoting it to science, it is now going into the drain of a Mars mission which will never launch, because Congress will never approve the hundreds of billions required.
The NGST (now named Webb) telescope has been in the works for years. It has a launch date of 2010. The Hubble reservicing mission was planned for 2006, and should have kept Hubble in operation until at least 2011 or 2012. That WAS a rational plan to keep the HST maintained, and to ensure than we have one optical space observatory in service at all times.
--RF
I agree that efficiency can save us factors of several, but there is one major issue which you have neglected -- that of the rise of the third world. Most of the world's population resides in underdeveoped nations, which are currently using very little power. As these nations become more developed, their energy consumption rates will skyrocket, just as ours did during the 19th and 20th centuries.
-- Bob
I am not certain how this got ranked to 5, but it is a common misconception, so allow me to clarify.
;-)
:-)
When all the stars burn out, space will start collapsing again as energy falls into black holes.
No. This is not how gravity, according to general relativity, works. The curvature of spacetime is, roughly speaking, proportional to its local mass/energy content. In fact, converting things into black holes doesn't change the curvature of spacetime to any substantial degree once you are more than a few Schwarzschild radii away -- Newtonian gravity works just fine in the far-field region. Therefore, as massive stars die out and form black holes, their gravitational field is not substantially affected far from them.
Incidentally, the vast majority of stars will not form black holes, but rather white dwarfs. Just so that you know.
We often toss out a question to the Astronomy 1 students tests their knowledge of this principles. What would happen to the Earth's orbit if the sun could be suddenly replaced by a black hole? Most students answer that the Earth would fall in. (Wrongo! Too many scifi movies.) Answer : the orbit is practically unchanged.
Ponder that, Chemisor.
--Bob
I'm a computational astrophysicist, so my main tools are computers. ;-)
But more generally, computers are nearly universally present in all scientific settings. Observers no longer gaze through the eyepiece of a telescope; they sit in a control room in front of a computer. (Observers who use Hubble, Chandra, or Spitzer, of course, never leave their computer in their office.) Similarly, few experiments generate reams of paper rolls of data anymore; almost all experimetnalists use a computer in some fashion to generate and analyze their results.
All of this begs the question... if in nearly any scientific setting you have a high-powered computer sitting right in front of you on your desk, why on Earth would you choose to use a hand-held calculator instead?
Bob
I agree that calculators are still useful for educational settings, although for a different reason that the one you suggest.
As a computational astrophysicist, I no longer find any use for hand-held calculators whatsoever. If I find the need to do a detailed numerical computation while working, I simply pop up Mathematica. I have hundreds of physical constants relevant for my work stored in a handy ".m" file, so if I wish to compute, say, the Planck mass, I can simply type in "Sqrt [hbar c / G]", rather than punching in numerical values. It is far more convenient and _more powerful_ than using a hand calculator since I can readily construct expressions, do symbolic manipulations on them, and produce complex plots with very little effort. Mathematica has an enormous understanding of mathematical functions, so if I want, say, the value of second derivative of the Laguerre polynomial of order n, I can simply enter "N [D [LaguerreL [n, x], x] ]". (Try to stuff than in your calculator and smoke it.) It also has unlimited numerical precision, so if I want the value of Pi to 100 digits, I just enter "N [Pi, 100]". (Not a practical example, given that 100 decades is greater than the total number of fundamental particles in the current Hubble radius, but an illustrative one nonetheless.) In addition, I have the ability to immediately translate those expressions into Tex format or C or Fortran code, so that they can be readily incorporated into papers or other standalone code. And that is saying nothing of the fact that a full-sized keyboard is vastly easier to use than _either_ a stylus or a weeny calculator keypad.
If I am in a meeting of some kind or just informally speaking to someone, and the need for a quick numerical estimate comes up, I can always whip out an estimate good to within 10% without using any calculating aid other than a pencil and paper. You'll find that all good scientists and engineers can do quick back-of-the-envelope calculations when the need arises.
So what use are calculators in schools when students could be using Mathematica (or any other mathematical software of their choice) on their laptops? The plain fact of the matter is that math and science instructors almost universally do not wish to construct a course in which the learning goes beyond the simplest applications of the principles learned. Therefore, they must almost always artificially control additional information and calculating aids during exams (normally no notes, books, or computers). Calculators are the one concession they do allow, only because their functionality is limited, and therefore the aid they provide is also limited. I admit calculators have become reasonably sophisticated as of late, and so as a result, partially to offset any potential unfair advantage, instructors are increasingly allowing students to stuff all of the equations they can fit onto a "cheat sheet" of a certain size.
When you think about the situation, it is fairly ludicrous. No literature professor would make a student write a term paper on Shakespeare without having access to the original plays and all the additional supplemental information he can lay his hands on. But it is easier to construct a system in which students are tested on rote memory and simple application of known template examples from class, rather than being able to use all the resources at their disposal to synthesize everything they have learned in creative applications. Synthesis and creative use of one's knowledge, is, after all, what real world science and engineering are all about. Primarily because of this artificial construction, classwork performance is quite often a poor indicator of a student's potential as a real scientist or engineer.
Bob
You have some good points, but there is one key distinction you are missing.
There IS certainly innovation among all those categories (books, films, music, etc.), but the VAST MAJORITY of the innovation is usually being made on a very small scale, with just a handful of talented individuals working on the edge. Movies are a great example. Blair Witch was not produced by a Hollywood theatre, nor are the dozens of indie films snatched up by Hollywood distributors at Sundance and other film festivals. They are made by a few people, almost always on a shoestring budget (often funded on someone's credit cards!). A number of these films are made with astonishingly low budgets... El Mariachi was done on $10K, and many not much more than that. The same goes for books (where just a single person working in their spare hours can produce the next classic), music, and zines.
Now... back to the game industry. What can anyone do with $10K these days? That would hardly be enough money to purchase one high-end workstation with Maya and other requisite software tools. You see, people are EXPECTING highly polished graphics and gameplay out of each new video game. Long gone are the days where a single Russian program can whip out Tetris in a few weeks of effort, and create a sensation. I'm sure that thousands of slashdotters have tremendous ideas for awesome games, and many of them have the programming skills to pull it off. But if they are to to compete with the current big-name titles, they have to play by their rules. Who will do the artwork? The motion capturing and animation? The original music score? The voice-overs? The analogy to films would be like if the movie-going audience demanded to see Return of the King-quality battles and special effects in EVERY film they see. If that were the case, then the indie film industry would be dead as a doornail too.
There is room for innovation here (think of games like Snood) but the game-going audience needs to lose their addiction to big-name licenses and fancy production values and focus on the one thing that gaming is about : fun.
Bob
Sujal :
Your point is well-taken. Stated simply, in your view, contextual phrases should be ranked according to usage.
But how are we to weigh the usage? Is every hit on every webpage of equal statistical relevance -- whether it is the New York Times or a random blogger?
The obvious answer is that, no, if one wants a meaningful search, some sites are more statistically relevant and should be weighted as such.
But if they are to be weighted, how? Does the NYT carry 10, 10^3, 10^6 times the relevance of a blogger? This factor is tied in in some fashion to how many sites link back to the site in question. But it can be washed out if a sufficiently large number of low-relevance sites are included. Hence we have phenomena such as Google bombing.
Although right now these effects are of "zero measure" (in Google's claim), I think the problem is continuously increasing, as people become aware of how Google operates, and can influence searches. For instance, it is easily conceivable to me that the first 10-20 searches of a third party political candidate could be swamped out by a highly devoted Google bombing on the part of his political rivals. That would be a serious misrepresentation of information, with potentially huge impact on the rest of us.
Bob
Have you even looked at the California Board website in question? At the very top of the page, there is a huge honking disclaimer that reads
"This list contains names of licensees for which accusations have been filed and are pending possible disciplinary action." (emphasis mine)
The crux of what this CPA is claiming in his case is that this information about a pending case against him is difficult to find on the CBA website, but it pops up immediately when you Google him. He believes this is how Google is "misrepresenting" the information.
No one is disputing the factuality of the information -- only the manner in which it is presented. No matter how you look at it, the CBA website should be responsible for the factual content, since they are putting the information out for the world to see. If the information should not be up yet, or it is not 100% accurate in every regard -- fine, but then the CBA should be responsible. If it is a matter of public record -- fine, but then why is this CPA bitch complaining?
Shortly after WWII, the United States decided that it should monitor dust particulates in the upper atmosphere to test for the possibility of an above-ground test by Soviets. The program itself was highly contoversial; Oppenheimer (falsely) thought the radioactive material would go into the atmosphere in a gaseous phase, and diffuse away so rapidly that it would never be detected. This turned out to be incorrect because a significant amount of radioactive material enters into solid particulates, which can float in long-lived clouds hanging in the upper atmosphere for weeks or months. Cold War generations knew this phenomenon as a terrifying, bone-chilling household word : fallout.
Still others in the military (noteable General Groves) smugly thought that it would take the Soviets decades to catch up, and hence there was no rush in setting up a detection system.
Much to everyone's shock and surprise, a scant few weeks after the program was initiated, positive results came back from the chemical analysis of the upper-atmosphere dust gathered on one mission. Hans Bethe and other experts were called in to interpret the findings. Not only could they determine the yield of the blast, but they could also infer the date (and hence, approximately, from prevelant winds, the location) of the blast, and even the composition and design of the device.
The implications were clear. Someone had filched the US design from the Manhattan Project, and the Soviets had the information. The seeds of the Cold War and McCarthyism were sown.
The most amazing twist to this story is that if the US had delayed its fallout survaillance program by just a few months, the Cold War would have been delayed by years -- until the Soviets tested their next device. That is not to say that there would never have been a Cold War. But the US would have lived on in its smug complacency for years longer, and McCarthyism as we know it today wouldn't have occurred as it did at that time. History might have turned out quite differently indeed...
If you find this story fascinating, you would get a kick out of reading "Dark Sun," which contains this en To answer the poster's question, clearly none of this is new. The point of the article is that much of the vigilance and expertise was allowed to dissipate after the Cold War ended. Now, post-9/11, the incentives for due dilligence are back...
I think this IBM device is the most innovative idea I've seen in "mobile" computing since the iPod. Basically, one carries around the CPU and hard drive of your computer, and docks it wherever you need to use it -- at home, at the office, in a mobile dock. It's the notion of a dock/laptop combination taken to its logical extreme. Plus, with some basic software installed, there would be no need for a separate portable media player ala iPod. It may very well revolutionize our way of thinking about computing.
I think ultimately the question is whether there is a single continuous "initial mass function" of isolated objects or not. The best idea as to how stars acquire their initial mass is that turbulence in the interstellar medium, which exists on all scales, establishes a power-law distribution of initial masses. Every once in a while, you get a very strong shock which passes by inside a giant molecular cloud and forces the collapse of a large region which then goes on to form a massive star. But more typically, you form stars more like our sun. And just as rare as massive collapses are very small mass ones which go on to form isolated brown dwarfs and free-floating planets. If this model holds up to be true, then we are all mincing words in our definitions of isolated systems, since they are all manifestations of the same universal formation process.
However, to avoid the difficult question of formation mechanisms, an IAU working group of some of the most respected people in the field established a working definition to define by fiat what it means to be a brown dwarf, and a planet. Extrasolar "planets" are those objects orbiting a star which are beneath the deteurium-burning limit -- regardless of how they are formed. "Brown dwarfs" are defined to be those which burn deuterium but not lithium, and "sub-brown dwarfs" (NOT free-floating planets!) are defined to be those isolated objects which do not burn deuterium. Even the working group itself admitted that this definition was not satisfying to a single member of the group, and so it is likely it will be replaced at a later time with something more physically-motivated. The "planet/planetismal/KBO" distinction was pushed back to our own solar system, since it will be some time before anyone sees anything that small in another system.
Also of interest is the following link, which gives a history of previous claims for additional planetary members of our solar system : SEDS.
You're absolutely right that we don't hear as much about radio astronomonical observations. There are probably a few reasons. The first stems from the fact that astronomers tend to specialize in a given waveband -- the knowledge and expertise that is required to observe in the optical is very different from that required to observe in the radio, and both are in turn radically different from that required to observe in gamma rays. A few exceptionally talented astronomers operate in a couple of bands, but almost none operate across the entire spectrum. Radio astronomers are a minority within the astronomical community, and while they do really great science, it is primarily on sources filled with cold gas or electrons gyrating in the magnetic field, and are somewhat more difficult to popularize than a snazzy Hubble photo. The other reason, I think, is largely cultural and political. NASA does a great job pushing its science (Hubble, Chandra, Spitzer, planetary missions) to the public's attention, and devotes a lot of its effort culling the media's attention. The remainder of the astronomical community, including the national radio and optical observatories, tends to be much more conservative, and does not make much of an effort to garner attention. Generally you will only hear of their work when the press appears at one of the American Astronomical Soceity (AAS) and snatches up a few of their stories to splash up in their papers and broadcasts.
This parent posting was really great, and I applaud the moderators who modded it up. However, sadly, it was the ONLY reasonable post modded at 5 -- the rest are just a bunch of idiots making stupid comments which some other idiot found funny. Posters and moderators should definitely try harder to keep postings on topic and technically worthy. That is, after all, what slashdot is all about.
Bob
The result? There were many goals described, some of which may now be in peril as a result of Bush's backhanded hit on science within NASA. Putting a man on the moon or on Mars is not on the list, however. You can read the brief summary here. The entire text of the report is availbale here. Although the entire text is well over 200 pages, there is a lot of material in it that sets it apart from most beauracratic reports, including some 40+ pages of a layman's discussion of the science driving the requests.
Bob
However, there is one ace card in Microsoft's back pocket which you left out : Microsoft's Theory Group. MS supports a very high-powered discrete math and computer science group, comparable to that of a top-notch university. It's not just deep pockets here : it's a long-term commitment to building up a substantial research group pursuing fundamental research on problems closely allied to various technical issues. Noteably, this includes web searches, which is really just a problem in graph theory.
One needs to be extremely cautious in comparing the relative maturity of two technologies. The IE/NS analogy shows that MS can rapidly catch up to an existing technology, since they can afford to outspend and outlast any competitor. The only survival strategy is to evolve more rapidly than MS can follow; NS failed in that game by version 4, and it has only been relatively recently that other browsers (noteable Mozilla and Safari) have posed serious competition to the now-stagnant IE. Based on the existing high-powered theory already within MS, I am willing to bet that not only will MS have caught up to Google within 1-2 years, but they very well may also proceed to blow right past them.
Bob
"Dear NYT editors: 'Copy Left' really shouldn't have a space in it. Thanks."
Bah. You marines are wimps. At Caltech and UC Berkeley, people go tunnelling for SPORT.
You're thinking of CYC, as in enCYClpedia. (The open source version of this system was released in the wake of the movie AI, and is available at opencyc.org. )
As another poster has pointed out, this project had nothing to do with heuristics, and everything to do with ontology -- that is, the formal specification of knowledge using logical constructs.
In the way of background, the project was the brainchild of Douglas Lenat, who proposed to take traditional AI technques to their limit by giving a computer program all of the knowledge of the world which a toddler might have. Once a computer (so his reasoning went) had that knowledge, it could then be fed additional facts, and it would be able to understand them as well, with some occasional guidance from humans (much as a toddler might). Eventually the program would have enough knowledge that The project took dozens of computer scientists and philosophers specalizing in ontology the better part of the 1990s, and was frequently covered in the popular press.
The end result had not been so widely discussed or covered. I infer the program was not in fact self-propagating as was intended. Clips I saw towards the end of the project showed the enormous potential problems in this approach. For instance, one might tell CYC about a electric shaver. Later that night, it would go through and find inconsistencies between this new knowledge and its existing ontological database. For instance, in the case of the electric shaver, it might ask whether the human was also an electrical appliance while using the shaver, because someone had previously specified a rule that anything incorporating an electrical appliance was itself an electrical appliance. Hence, I gather that rather becoming self-propagating, the larger the ontological database became, the greater the number of logical inconsistences that arose, thereby miring the entire approach. At some point, progress would presumably be bottlenecked by the fact that many ontological experts trained in the CYC software would have to be working around the clock to attempt to sort out these problems.
Is anyone aware of any software projects that actually use CYC or openCYC? I am also greatly interested if anyone has a link to a good discussion by Lenat or others on their assessment of the CYC project at its completion. It is a monumental chapter in the history of AI, but despite this, I have never seen many technical articles published by CYC team members. I suspect that it may be nearly impossible to have a fully self-consistent set of ontological definitions of the world in the manner that CYC attempted. If so, that would be an amazing statement about AI, and indeed, the nature of knowledge itself.
Bob
I totally agree with you. NASA is an enormous enterprise, and although the manned spaceflight missions get most of the attention (and budget), the unmanned missions and satellites and hard astrophysics funded by NASA make a vastly more significant science impact. This is coming from someone who got his graduate research supported by a generous NASA fellowship under the GSRP program.
Just the great observatories program alone -- Compton, Hubble, Chandra, and now Spitzer -- each constructed and launched with roughly $1 B, underline the point that when TENS of billions of dollars get shifted around, science could very well be left out in the cold.
Moreover, the THEORY portion of NASA's science is peanuts of the overall science program, which is itself peanuts of the overall NASA budget. Each year, over a hundred PIs go all out to fight for the few million dollars provided by NASA's Astrophysics Theory Program (ATP). About a dozen are actually funded, to the tune of about $100 K each. The irony is that after all those tens of billions of dollars are spent on launching people on top of firecrackers and designing and building telescopes and satellites, only a miniscule amount is devoted towards our physical understanding of those observations.
I totally agree. I read about this poster several months ago when it first appeared as a preprint on the astro-ph preprint server. I loved it so much that I printed out the postscript version to put on the door of my office at work.
Almost any technically-minded person who stops to look at it finds it very cool, and often has questions about it. The mark of its usefulness as a teaching tool is the fact that many cool astronomical facts can be picked up simply by carefully looking at it. For instance, there is an enormous gap in the Sloan Digital Sky Survey galaxies when plotted on this map. At first you may think it is simply an artifact, but actually it occcurs where we are trying to peer through the center of the galaxy -- the so-called "zone of avoidance". It shows up on the plot because the data are plotted in galactic coordinates. The plot is rich in such detail. A few more are mentioned in the astro-ph paper; truly curious and interested folks would benefit from reading it.
Bob
Wrongo. Note that none of these preprints (dealing specifically with the gravistar concept) are peer-reviewed.