Okay, I'll simplify everything I'm going to say right now. Learn the actual economics and physics of the situation, because your ideas are wrong.
It takes about a week to launch something via a space elevator, so pipelining means you can launch as many payloads as you have climbers, basically. This puts you FAR above the capabilities of rocket-type launchers.
Also, the reason people "forget" about rotational inertia is that it doesn't apply. You're stealing rotational inertia from the Earth to speed things up. Gravity keeps it from slowing down.
What the hell is it with everyone thinking that the starship collision scene was wrong? Here's a hint - it wasn't. It was fine. Two ships colliding in space, if they have a SERIOUS amount of structural integrity (bulkheads and the like) will be fine. They'll crush until the impulse is burned out (f delta t = m delta v and all that), and afterwards, when one pulls away from the other, they will rip up each other as the poor joints fail to communicate the large amount of stress imposed upon them.
I saw one or two film reviewers try to bash the physics in that scene based on "there's no friction in space!" or "they would've just kept going, and not crushed into them!"
Here's a brief reminder:
Friction exists between any two bodies that have a force that's perpendicular to their surfaces as well as a force that's parallel to their surfaces. The frictional force is parallel to the surface, directed against the force being applied, and is proportional to the force perpendicular to the surface. You don't need gravity. You need a normal force. And any two objects that aren't perfectly parallel to each other that are forced against each other will exhibit that.
Also, inertia works the same in space as it does on Earth. An inelastic collision will dissipate a large amount of energy in the form of heat and vibration.
Two massive ships colliding in space will act just like two massive ships colliding on the ocean. The only difference is that when one of the ships tries to pull away from the mass of jumbled metal, on Earth, they won't be able to (very easily) because gravity provides a normal force on all surfaces that are touching. In space, they will pull away somewhat easily (which is what happened), but friction will still rip portions of the ships to shreds wherever two materials collide.
What friction? There's no "automatically generated" normal force like on Earth. In space, you only get friction between two objects that have portions that are in contact perpendicular to the direction of motion.
The tangled mass of metal would probably have given way before long, but not instantly as there is still a lot of friction to deal with. Those were some nasty gouge marks.
What causes things to not give way on Earth is static friction. There would be very little static friction (compared to the force that's being applied) and the force being applied was incredibly superior to the static friction between the few pieces of metal that ended up perpendicular to each other. There would be a fair amount of dynamic friction due to non-parallel directions of motion, but they would NOT "just stick together."
What happened in the movie was correct. Actually, there was probably too much friction, rather than too little. When the Scimitar fired its engines, it probably would have pulled immediately away from Enterprise, as the "joins" that had formed between the Scimitar and Enterprise had virtually no surface area in contact to support the stress being placed on it.
When Apollo 13 had its accident mid-flight, and on the return trajectory, when they fired the LEM engines, they were worried about the ship tearing in two because the connections between the ship and the LEM might not be able to support the stress being placed on them. Same deal. You don't need an "opposing force" to not have something move. Newton's 3rd law gives you the opposing force.
I don't think you understood what I said. The thing is that the rendering path only asked for 96 bit precision - however the NV30 had to render it in 128 bit because it doesn't have a 96 bit mode. You're not going to get "free" improved image quality simply by calculating things out to more precision.
It's like in freshman-level science classes - you don't take the numbers out to more significant figures than you start with, because the added precision is meaningless. Carmack was talking about fragment path programs, for which added precision probably wouldn't pan out to added image quality.
No - this is decidedly not what he said. What he said was that the ATI precision mode that is used doesn't correspond to a precision that NVIDIA uses on the NV30, and the ARB2 precision mode corresponds to what ATI is using, but is "between" two for NV30. So the NV30 has to render it at its highest precision (rather than rendering it at a lower precision and artifacting the hell out of the thing) which slows it down.
The thing is that the renderer didn't want the higher precision, so the excess precision is mostly wasted. It's like calculating out 1.5000 * 1.5000 and getting 2.2500, and then truncating it back to 2.2. You could've just truncated it to 1.5 and 1.5 initially, and gotten 2.2 as well.
So, I doubt that NVIDIA actually looks better in the ARB2 mode. It just runs slower, because it's calculating things that don't need insane precision to insane precision.
Hence the reason that Carmack said that NVIDIA is confident there's a lot of room to improve, if it can realize which of the three precision modes is most ideal and shift to it.
A "law" in science is more of an empirical observation - a guideline or principle. Kindof like Moore's Law. In general relativity, there's the "Law of Cosmic Censorship" which states that you can't have a singularity without an event horizon cloaking it. A much better mathematical term for what some scientists tend to use "law" for is "conjecture" or "principle".
Is it poor wording? Yah, but using "law" to describe a proven theory is falling by the wayside, since very little is truly provable, so "law" is almost getting a comic connotation.
Newton's third law is even pretty much a "conjecture", since we know the strong form of it isn't true in all cases, and while the weak is holding extremely well, it's entirely possible it may not be completely true.
Are you sure about this? Traditionally, a "nova" occurs when accreting material builds up enough on a white dwarf to retrigger fusion burning, resulting in a rather large "Boom!" as all of the fresh yummy hydrogen goes away relatively rapidly. This isn't really the same thing - the triple-alpha process is becoming unstable inside the star, occasionally shoving large quantities of gas off the star when a large supply of helium reaches the core. It's a "dying planetary nebula", basically.
"Novae" were named because they were "new stars" that showed up out of nowhere (because the white dwarf was originally nowhere near visible) and then disappeared. Rho Cas isn't like that - it's bright enough to be seen normally, but is changing its brightness rapidly.
It definitely looks like it's going to go supernova, though. I don't know its actual mass, so I'm not sure whether or not it's an "absolute given" or not.
Planets that have burned up their deuterium still have 10-12 times Jupiter mass - it's just that some percentage of it is deuterium. I really don't see what's wrong with the current brown dwarf definition of an object which can complete, has completed, or would be able to complete a portion of the pp chain at its core, but not all of it. This will give a cutoff of about 10-12 M_j, as you said.
The problem with the cutoff of how mass affects radius is that it's dependent upon a lot of other things besides mass (composition, and nuclear activity), whereas when you're in the 10-12 M_j range, regardless of what is actually at the core, you're probably going to be able to fuse deuterium. Again, it's an arbitrary fuzzy dividing line, but considering you're in the range of talking about "stars", which are all about nuclear fusion ("brown dwarf": portions of the pp chain only, "normal dwarf" - pp chain, "giant" - triple alpha chain) it's better to use a definition based on nuclear fusion to define it.
Actually might make more sense to add an additional distinction in the 2-3 M_j range too: gas supergiants. So gas giants = objects primarily composed of gases and 2-3 M_j but unable to sustain any nuclear fusion in their core, and brown dwarfs = objects > 10-12 M_j but unable to complete the pp chain.
I dunno, I suppose I look at it from the aspect that if I have free time I'd be using it to play with my kids, practise guitar or whatnot, not work on an electronics project since that's what I do for a living. And if I am working on an electronics project, I may as well be getting $35/hr+ for it.
Some people practice guitar in their free time, others work on electronics projects, even if that is what they do for a living (like me). If you don't mind doing it, using your free time to save yourself $100 is a huge bargain, considering normally you don't get anything for it (other than enjoyment, satisfaction, etc., all that intangible crap:) - note the sarcasm).
Again, if you've got the time, patience and ability to do FPGA synthesis then sure, but the potential to do so much more is a joke because you'll be modifying the hardware to take advantage of pretty much any gain in features.
FPGA synthesis is writing code. That's it. It's not magic, it's not even that difficult. And this isn't even pure hardware, or pure FPGA logic - he implemented a CPU, so adding features (like changing 'channels' - different streams) is just adding code. Pretty trivial.
Show me where you can get a case that looks like it belongs in a home entertainment system for $3. I'll concede on the power supply.
A junkyard, actually, or go to an old radio repair shop and buy a damaged/destroyed component case (that is, a case where the component inside is dead, but the case is good). Easy enough.
Besides, you don't need a case that looks like it belongs in a home entertainment system. That's not what it's for - it's for redirecting audio via ethernet. And for that, it IS quite cheap. Especially if this guy gets intelligent and starts selling the PCBs for quantity price, cutting down the (admittedly already cheap) PCB price.
Personally if I were him I'd definitely just sell the PCBs and parts from quantity pricing and make a quick buck without having to assemble them - sell PCB+parts kit+schematics for, say, $50-60, and then it's just plain cheap.
Oh yes, and time is worth something. If you choose to hack on a device or play with your kids, that's time you could be making money with. It's all priorities. Money isn't everything, but that doesn't mean that time is cheap or free.
Bull. I'm salaried, as are many people in a professional career, and I can't make more money by spending more time working. Could I work another job? Yah, but that takes more dedication and prioritization than a simple hobby project. Actually, for me, I don't consider time = money at all - I consider stress = money, and my free time is low/no stress. This project can take all the time it wants, so long as it doesn't stress me out too much, and I'd consider it free. From what I've seen of the design, it'd be pretty friggin' easy for me.
Besides, I didn't say -any- time was free, I said free time was free. If you set aside a block of time as "this is my free time" then it's free. You can't claim that that time is worth $x per hour, because it's already reserved for "nothing".
You can't compare this to an Audiotron or a slimp3 - it's not the same thing. It's not an "active player" - it's a simple solution to redirecting audio over ethernet. And if that's all you want, then spending $200+ for something that does way more than what you want is crazy. You want something small, unobtrusive, that you can stick by a pair of speakers and poof, extend audio into another room.
The middles are better because they allow for misregistration better - depending on how good you are, it won't matter, but if you tend to screw up trying to get the corners, the middles will be more forgiving.
The method you mentioned is fine as well - the one drawback is that you'll come across loose pins more often than just lathering the whole thing in solder and cleaning up afterwards. You DEFINITELY have to be careful about anything that's going in wacko temperatures (like outside, but why the hell would you do this for something that goes outside?) because pushing on pins won't find "weak" joints - ones that will go when thermally stressed.
A needle works quite well for finding weak joints also - the dentist's pick tends to "flex" a little more when doing it, but I keep going back and forth between the two depending on my mood. If you're patient and want to be thorough, I think the needle's better - if you're in a hurry and want it to work 90% of the time (rather than 100) the dentist's pick goes much much quicker.
I had to work through 80 288-pin QFPs finding loose joints - I think I lost a few years off my eyesight that way...
Your free time is free, by definition. You can't buy an Audiotron for $150.
You can't charge yourself, and unless you're psychotic and expect to get paid during the time when you're not working, free time is free.
Moreover there are quite a few things you can do with an fully programmable FPGA that you can't do with an Audiotron.
For one, as someone pointed out, you can easily adapt this thing to draw power from Ethernet, and you eliminate the power need. Plus making it not require Windows is pretty damn easy as well. You, however, do NOT want it to access an MP3 store - that's not what this thing does. You could easily redirect an Internet radio feed through this thing - or audio from a video game, etc. Anything you want.
And a cheap AC/DC converter is $5 from Radio Shack, and the case is about $3. I doubt they contribute significantly.
Well, you COULD use this and add an 802.11 bridge. All this thing wants is Ethernet - it doesn't care HOW it gets it. If you've got 802.11 already, you could just put the access point by this thing. Depending on your setup it could be identical to what you need - otherwise you'd need to pick up an access point for about $100 or so.
There were no schematics. There were no gerbers. There was no FPGA sourcecode. There was no driver sourcecode.
In fact, there was NOTHING there other than pictures.
My guess is that he was feeling to see if there's a market, and then if not, releasing everything. Personally I would've rather he released everything, THEN submitted it to Slashdot, rather than using Slashdot to feel for a market.
As for the actual cost of building it: it'll be under $100. The PCB is $26 from the vendor he got it from. The Xilinx FPGA is $14, and the rest of the parts probably total about $30, at best. LCD screens would be easy to add on, and they cost basically nothing ($20 or so). You could even add an infrared remote if you felt like it pretty easily. (be about $20 or so for the HSDL-1001 & 7001 pair, and then need to implement a UART).
If you can do the work, and put in the time, you can easily make it for far less than $250, and far less than $150, as well, with basically any features you want.
Nope, not unless he works for Xilinx, as his name is silkscreened on the board. He bought the FPGA from Xilinx, had the board made at a cheap board house (the cheapest, from what I've seen... though they don't look that bad), and soldered them himself.
Done well reflow soldering kicks ass (hence the reason why there's a very advanced toaster oven sitting about 10 feet behind me) but the problem is that you really do want the "very advanced" toaster oven if you're going to do this - one with a temperature profile that's settable (or at least one that's designed to solder, rather than cook). With an incorrect profile, the part will probably misregister and yank to the place where the solder happened to be the most. So I really wouldn't recommend homebrew reflow soldering with fine-pitch components - it won't work well.
Hell, hot air soldering fine-pitch components doesn't work that well either. Fine pitch is just not easy without a fine hand and a microscope.
... and what do you know, he did go through Olimex for the PCBs. OK, so apparently they don't suck. $26 for double-layer soldermask and silk is completely insane. Granted it doesn't include shipping, but who cares? It's practically free.
Soldering flat pack devices is a bit of a pain, but there are a few tricks that you can use to get it to work. The solder paste/toaster oven trick is a poor man's reflow oven, and I wouldn't recommend it, as especially with flat packs, you'll have as much problems getting the thing registered correctly as you would with a fine tip soldering iron.
Best way to do this is lots of solder, and lots of flux. You can cheat as well if you want - get it registered correctly (do the middles of each side) and then literally bathe each side in solder. Don't worry about bridging - you just want every joint made. Then go back with solder wick and very carefully remove the solder inbetween the pins. It's crufty, and you need to be a bit careful, but it is very quick and it does work.
BTW, circuit boards are cheap through the right vendors. CustomPCB for instance is $50 for a single-layer solder-masked circuit board (4 of them, to be specific) and Olimex (who I've never gone through) is even cheaper - $26 for double-layer with soldermask & silk.
Bizarrely enough, the answer to that is most likely "yes", because the chromosphere thermalizes gamma radiation from the core. Though, somehow, my guess is that the "chromosphere shoved off of a star" model for gamma ray bursts wouldn't work that well. Then again, who knows, theorists can do wondrous things with models...
And if you remember relativity, when an object is travelling near the speed of light, the mass increases. So the theory at least makes sense. Here's another thing to ponder. If an object the size of the sun suddenly acquired the 99x its mass, would it not either collapse upon itself, or expand rapidly, nova, and the core would collapse upon itself, causing the same result, a singularity, with a small event horizon. And it will be this singularity that will collide with Earth, ripping through it in a fraction of a second, and the sudden, combined gravitational effect on earth will cause it to very suddenly pull out of it's orbit toward the origninal center of gravity of the sun, with a nice city sized hole carved through it.
point of note: a "nova" is what happens when fresh yummy hydrogen falls on a white dwarf. Boom! A "supernova" is what you were talking about. Confusing the two is a little dangerous, because they're two completely different processes.
Depends on the mechanism of acceleration, really. If it's merely "moving" at a Lorentz factor of 100, then no, of course not, because all you did was Lorentz boost the system, which you can always do. In the Sun's rest frame, it's fine still, of course. In the boosted frame, it's also incredibly flattened (like a pancake - by a factor of 100, no less) but amazingly enough, you can still work out hydrostatic equilibrium for it, and determine that yes, it is still in equilibrium, and not going to blow up. Beauty of relativity - laws of physics are Lorentz boost invariant.
However, if you're actually accelerating the thing, now that's a different story. You (still) won't make it go supernova, because you're NOT actually increasing the number of particles inside it, and that's what breaks hydrostatic equilibrium - pressure generated versus gravity, and BOTH of those change in the boosted frame - but you WILL screw it up really badly by sending pressure bubbles through the whole thing. Since the Sun isn't a rigid body, you'll probably strip the chromosphere right off of it, and leave the core bare. This, however, won't due much except really really confuse distant astronomers.
First, most stars are binaries, not one out of ten. The figure is something like 2/3, I think. Don't quote me on that, it's from a class about 5 years ago.
Second, tidal forces on Earth do NOT cause our magnetic field. Take the Moon, for example - it stresses us tidally, and we stress the hell out of it tidally (hence the reason that it faces us). But it doesn't have a magnetic field at all. Our magnetic field is caused by our high rotation and due to the fact that we still have a molten core. Mars rotates quickly, but does not have a molten core, so no magnetic field. Venus has a molten core, but doesn't rotate, so it doesn't have a magnetic field. Mercury has a magnetic field, though it's weak, and it is most likely due to the fact that the planet has no crust - it's fundamentally just the core of a planet that cooled and stopped spinning, so its magnetic field was frozen in (it's a giant ferromagnet).
Third, the Earth/Moon is not a binary: the barycenter of rotation is inside the Earth. The Moon orbits us. We don't orbit the Moon. With Pluto/Charon, that's not the case - the barycenter of rotation is in empty space. Pluto orbits empty space, and Charon orbits empty space. That's a binary. We're a planet/satellite system.
Last points: the axis tilt stuff IS right. Search around a bit - it's recent (1995 or so, if memory serves) but take a look at Mars, for instance, which (lacking a moon) swings between 15 and 35 degrees. And the solar wind would not strip away atmosphere - it would destroy the ozone layer, and ionize water, but it would not "strip away" atmosphere. That's ridiculous - the solar wind is almost all protons, which wouldn't have any chance of knocking a nitrogen nucleus out of Earth's atmosphere, and if it did, there aren't enough particles to make a dent anyway.
Gravitational perturbations from other planets and tidal effects. Without one strong dominant tidal force (year round) Earth's axis would slowly precess and move around.
Look it up: just google for earth axis moon stabilize, and there are about a hundred links on it.
Incidentally, the axis of rotation does shift - with a period of about 41,000 years currently. That's "suddenly" on a geological/evolutionary scale.
Actually, he is correct - the tidal influence of the Moon is what keeps Earth's axis stable. Without the Moon, the other planets in the solar system would tug slightly on Earth as it rotates and cause it to "wobble" on its axis.
The reason for this is rather simple: the Moon is the largest contributor to the tidal forces acting on the Earth - all the other tidal effects are merely corrections on the Moon's, and the Moon forces a steady small oscillation (precession). Earth's angular momentum actually isn't large enough to keep its axis stable - if it were significantly faster or slower, it would be stable. If faster, the torque required to change the axis would be huge, and if significantly slower, the rotational tidal effects would be negligible.
Mars, for instance, spins quite fast (due to repeated asteroid collisions) and has a very unstable axis - it swings between 15 and 35 degrees, with longer period oscillations between 0 and 60 degrees.
Venus is virtually tidally locked, but does have a slight rotation (in a tidal resonance with Earth) but spins so slow that its axis is stable. Ditto with Mercury.
There have been several (AimSTAR for one) serious proposals to NASA for interstellar probes that travel at significant fractions of lightspeed (0.3c in the proposal I saw). At that speed it would take only about 12 years to reach Alpha Centauri, and only around 30 or so years to reach a good number of stars. Definitely doable. (Most of these were ultralight antimatter fueled probes, and NASA didn't pick them up.)
The other thing to remember is that time dilates near light speed, so for the object that's traveling, faster than light speed is easy. How fast do you want to get to Epsilon Eridani (a sunlike planet 10 light years away with a known Jovian-like planet)? 5 years? No problem. Travel at about 0.7c. 1 year? 0.95c. It will still take 10 years (or so) according to Earth, but not to the people on board.
Also, a little more offbeat, yes, but faster than light travel is not impossible - just "likely to be impossible". Relativity is what says "FTL travel is impossible" and general relativity allows for multiply connected spacetime (wormholes) which would let you "effectively" move faster than the speed of light, and also the "moving walkway" effect (the Alcubierre effect) - that is, even though matter has a "maximum speed limit", space itself does not, so if you could move space around, you could drag yourself faster than the speed of light.
Anyway, interstellar travel isn't impossible. It isn't even that difficult. It's just an engineering problem. Give it time.
I'm pretty sure that all life needs water. You may be thinking of extremophiles, which live in conditions that are near boiling of water, etc, but they still need water. Water is life. It's not just thinking inside the box - it's basic physics. Water is a very strong simple dipole (hydrogen + carbon is not, hydrogen + nitrogen is too weak, and hydrogen + fluorine is not: ditto for H+Li, H+B, etc.) and dipoles are needed to form complex chemistries that wouldn't exist elsewhere - weak bonds, etc. Even things that live in completely arid conditions need water - they covet it like mad. That's because water allows certain reactions to occur that would never occur, and it rips ionic compounds apart. You'd never get sodium chloride apart without a dipolar compound, and a strong one at that, which means you'd never get sodium or chloride into your chemistry, which means less variation.
"Arid" and "extreme temperatures/pressures" don't equal "no water" - if water can't exist, you don't have life - at least, not life based on chemistry, and not prolific life. Try forming a chemistry based on some wacko chemistry and you'll probably have the simple problem of not enough of the atoms exist. We're based on H, and CNO. If you ignore helium and neon (which are not chemically reactive) those are the four most abundant elements in the Universe. That's not being anthrocentric. It's cosmology. I doubt it's coincidence.
That's not true. Venus is tidally locked, and Earth would've been tidally locked as well, but we got thwacked by a very large object (the Moon). Objects that are close in do lose their rotational velocity due to tidal slowing, but depending on the situation, that could take either a very long time, or be disrupted due to another planet.
Venus, for instance, is not perfectly tidally locked - it's in a resonance with Earth, which is why its day is not completely equal to its year. Ditto with Mercury, which has a 2:3 resonance.
If you consider the tidal slowing of the Moon, it's still extremely slow: the day is increasing by about 23 seconds per million years. The Moon and the Earth will be tidally locked after about tens of billions of years.
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Okay, I'll simplify everything I'm going to say right now. Learn the actual economics and physics of the situation, because your ideas are wrong.
It takes about a week to launch something via a space elevator, so pipelining means you can launch as many payloads as you have climbers, basically. This puts you FAR above the capabilities of rocket-type launchers.
Also, the reason people "forget" about rotational inertia is that it doesn't apply. You're stealing rotational inertia from the Earth to speed things up. Gravity keeps it from slowing down.
What the hell is it with everyone thinking that the starship collision scene was wrong? Here's a hint - it wasn't. It was fine. Two ships colliding in space, if they have a SERIOUS amount of structural integrity (bulkheads and the like) will be fine. They'll crush until the impulse is burned out (f delta t = m delta v and all that), and afterwards, when one pulls away from the other, they will rip up each other as the poor joints fail to communicate the large amount of stress imposed upon them.
I saw one or two film reviewers try to bash the physics in that scene based on "there's no friction in space!" or "they would've just kept going, and not crushed into them!"
Here's a brief reminder:
Friction exists between any two bodies that have a force that's perpendicular to their surfaces as well as a force that's parallel to their surfaces. The frictional force is parallel to the surface, directed against the force being applied, and is proportional to the force perpendicular to the surface. You don't need gravity. You need a normal force. And any two objects that aren't perfectly parallel to each other that are forced against each other will exhibit that.
Also, inertia works the same in space as it does on Earth. An inelastic collision will dissipate a large amount of energy in the form of heat and vibration.
Two massive ships colliding in space will act just like two massive ships colliding on the ocean. The only difference is that when one of the ships tries to pull away from the mass of jumbled metal, on Earth, they won't be able to (very easily) because gravity provides a normal force on all surfaces that are touching. In space, they will pull away somewhat easily (which is what happened), but friction will still rip portions of the ships to shreds wherever two materials collide.
What friction? There's no "automatically generated" normal force like on Earth. In space, you only get friction between two objects that have portions that are in contact perpendicular to the direction of motion.
The tangled mass of metal would probably have given way before long, but not instantly as there is still a lot of friction to deal with. Those were some nasty gouge marks.
What causes things to not give way on Earth is static friction. There would be very little static friction (compared to the force that's being applied) and the force being applied was incredibly superior to the static friction between the few pieces of metal that ended up perpendicular to each other. There would be a fair amount of dynamic friction due to non-parallel directions of motion, but they would NOT "just stick together."
What happened in the movie was correct. Actually, there was probably too much friction, rather than too little. When the Scimitar fired its engines, it probably would have pulled immediately away from Enterprise, as the "joins" that had formed between the Scimitar and Enterprise had virtually no surface area in contact to support the stress being placed on it.
When Apollo 13 had its accident mid-flight, and on the return trajectory, when they fired the LEM engines, they were worried about the ship tearing in two because the connections between the ship and the LEM might not be able to support the stress being placed on them. Same deal. You don't need an "opposing force" to not have something move. Newton's 3rd law gives you the opposing force.
I don't think you understood what I said. The thing is that the rendering path only asked for 96 bit precision - however the NV30 had to render it in 128 bit because it doesn't have a 96 bit mode. You're not going to get "free" improved image quality simply by calculating things out to more precision.
It's like in freshman-level science classes - you don't take the numbers out to more significant figures than you start with, because the added precision is meaningless. Carmack was talking about fragment path programs, for which added precision probably wouldn't pan out to added image quality.
No - this is decidedly not what he said. What he said was that the ATI precision mode that is used doesn't correspond to a precision that NVIDIA uses on the NV30, and the ARB2 precision mode corresponds to what ATI is using, but is "between" two for NV30. So the NV30 has to render it at its highest precision (rather than rendering it at a lower precision and artifacting the hell out of the thing) which slows it down.
The thing is that the renderer didn't want the higher precision, so the excess precision is mostly wasted. It's like calculating out 1.5000 * 1.5000 and getting 2.2500, and then truncating it back to 2.2. You could've just truncated it to 1.5 and 1.5 initially, and gotten 2.2 as well.
So, I doubt that NVIDIA actually looks better in the ARB2 mode. It just runs slower, because it's calculating things that don't need insane precision to insane precision.
Hence the reason that Carmack said that NVIDIA is confident there's a lot of room to improve, if it can realize which of the three precision modes is most ideal and shift to it.
A "law" in science is more of an empirical observation - a guideline or principle. Kindof like Moore's Law. In general relativity, there's the "Law of Cosmic Censorship" which states that you can't have a singularity without an event horizon cloaking it. A much better mathematical term for what some scientists tend to use "law" for is "conjecture" or "principle".
Is it poor wording? Yah, but using "law" to describe a proven theory is falling by the wayside, since very little is truly provable, so "law" is almost getting a comic connotation.
Newton's third law is even pretty much a "conjecture", since we know the strong form of it isn't true in all cases, and while the weak is holding extremely well, it's entirely possible it may not be completely true.
Are you sure about this? Traditionally, a "nova" occurs when accreting material builds up enough on a white dwarf to retrigger fusion burning, resulting in a rather large "Boom!" as all of the fresh yummy hydrogen goes away relatively rapidly. This isn't really the same thing - the triple-alpha process is becoming unstable inside the star, occasionally shoving large quantities of gas off the star when a large supply of helium reaches the core. It's a "dying planetary nebula", basically.
"Novae" were named because they were "new stars" that showed up out of nowhere (because the white dwarf was originally nowhere near visible) and then disappeared. Rho Cas isn't like that - it's bright enough to be seen normally, but is changing its brightness rapidly.
It definitely looks like it's going to go supernova, though. I don't know its actual mass, so I'm not sure whether or not it's an "absolute given" or not.
Planets that have burned up their deuterium still have 10-12 times Jupiter mass - it's just that some percentage of it is deuterium. I really don't see what's wrong with the current brown dwarf definition of an object which can complete, has completed, or would be able to complete a portion of the pp chain at its core, but not all of it. This will give a cutoff of about 10-12 M_j, as you said.
The problem with the cutoff of how mass affects radius is that it's dependent upon a lot of other things besides mass (composition, and nuclear activity), whereas when you're in the 10-12 M_j range, regardless of what is actually at the core, you're probably going to be able to fuse deuterium. Again, it's an arbitrary fuzzy dividing line, but considering you're in the range of talking about "stars", which are all about nuclear fusion ("brown dwarf": portions of the pp chain only, "normal dwarf" - pp chain, "giant" - triple alpha chain) it's better to use a definition based on nuclear fusion to define it.
Actually might make more sense to add an additional distinction in the 2-3 M_j range too: gas supergiants. So gas giants = objects primarily composed of gases and 2-3 M_j but unable to sustain any nuclear fusion in their core, and brown dwarfs = objects > 10-12 M_j but unable to complete the pp chain.
I dunno, I suppose I look at it from the aspect that if I have free time I'd be using it to play with my kids, practise guitar or whatnot, not work on an electronics project since that's what I do for a living. And if I am working on an electronics project, I may as well be getting $35/hr+ for it.
:) - note the sarcasm).
Some people practice guitar in their free time, others work on electronics projects, even if that is what they do for a living (like me). If you don't mind doing it, using your free time to save yourself $100 is a huge bargain, considering normally you don't get anything for it (other than enjoyment, satisfaction, etc., all that intangible crap
Again, if you've got the time, patience and ability to do FPGA synthesis then sure, but the potential to do so much more is a joke because you'll be modifying the hardware to take advantage of pretty much any gain in features.
FPGA synthesis is writing code. That's it. It's not magic, it's not even that difficult. And this isn't even pure hardware, or pure FPGA logic - he implemented a CPU, so adding features (like changing 'channels' - different streams) is just adding code. Pretty trivial.
Show me where you can get a case that looks like it belongs in a home entertainment system for $3. I'll concede on the power supply.
A junkyard, actually, or go to an old radio repair shop and buy a damaged/destroyed component case (that is, a case where the component inside is dead, but the case is good). Easy enough.
Besides, you don't need a case that looks like it belongs in a home entertainment system. That's not what it's for - it's for redirecting audio via ethernet. And for that, it IS quite cheap. Especially if this guy gets intelligent and starts selling the PCBs for quantity price, cutting down the (admittedly already cheap) PCB price.
Personally if I were him I'd definitely just sell the PCBs and parts from quantity pricing and make a quick buck without having to assemble them - sell PCB+parts kit+schematics for, say, $50-60, and then it's just plain cheap.
Oh yes, and time is worth something. If you choose to hack on a device or play with your kids, that's time you could be making money with. It's all priorities. Money isn't everything, but that doesn't mean that time is cheap or free.
Bull. I'm salaried, as are many people in a professional career, and I can't make more money by spending more time working. Could I work another job? Yah, but that takes more dedication and prioritization than a simple hobby project. Actually, for me, I don't consider time = money at all - I consider stress = money, and my free time is low/no stress. This project can take all the time it wants, so long as it doesn't stress me out too much, and I'd consider it free. From what I've seen of the design, it'd be pretty friggin' easy for me.
Besides, I didn't say -any- time was free, I said free time was free. If you set aside a block of time as "this is my free time" then it's free. You can't claim that that time is worth $x per hour, because it's already reserved for "nothing".
You can't compare this to an Audiotron or a slimp3 - it's not the same thing. It's not an "active player" - it's a simple solution to redirecting audio over ethernet. And if that's all you want, then spending $200+ for something that does way more than what you want is crazy. You want something small, unobtrusive, that you can stick by a pair of speakers and poof, extend audio into another room.
The middles are better because they allow for misregistration better - depending on how good you are, it won't matter, but if you tend to screw up trying to get the corners, the middles will be more forgiving.
The method you mentioned is fine as well - the one drawback is that you'll come across loose pins more often than just lathering the whole thing in solder and cleaning up afterwards. You DEFINITELY have to be careful about anything that's going in wacko temperatures (like outside, but why the hell would you do this for something that goes outside?) because pushing on pins won't find "weak" joints - ones that will go when thermally stressed.
A needle works quite well for finding weak joints also - the dentist's pick tends to "flex" a little more when doing it, but I keep going back and forth between the two depending on my mood. If you're patient and want to be thorough, I think the needle's better - if you're in a hurry and want it to work 90% of the time (rather than 100) the dentist's pick goes much much quicker.
I had to work through 80 288-pin QFPs finding loose joints - I think I lost a few years off my eyesight that way...
Your free time is free, by definition. You can't buy an Audiotron for $150.
You can't charge yourself, and unless you're psychotic and expect to get paid during the time when you're not working, free time is free.
Moreover there are quite a few things you can do with an fully programmable FPGA that you can't do with an Audiotron.
For one, as someone pointed out, you can easily adapt this thing to draw power from Ethernet, and you eliminate the power need. Plus making it not require Windows is pretty damn easy as well. You, however, do NOT want it to access an MP3 store - that's not what this thing does. You could easily redirect an Internet radio feed through this thing - or audio from a video game, etc. Anything you want.
And a cheap AC/DC converter is $5 from Radio Shack, and the case is about $3. I doubt they contribute significantly.
Well, you COULD use this and add an 802.11 bridge. All this thing wants is Ethernet - it doesn't care HOW it gets it. If you've got 802.11 already, you could just put the access point by this thing. Depending on your setup it could be identical to what you need - otherwise you'd need to pick up an access point for about $100 or so.
You're right about a few things:
There were no schematics.
There were no gerbers.
There was no FPGA sourcecode.
There was no driver sourcecode.
In fact, there was NOTHING there other than pictures.
My guess is that he was feeling to see if there's a market, and then if not, releasing everything. Personally I would've rather he released everything, THEN submitted it to Slashdot, rather than using Slashdot to feel for a market.
As for the actual cost of building it: it'll be under $100. The PCB is $26 from the vendor he got it from. The Xilinx FPGA is $14, and the rest of the parts probably total about $30, at best. LCD screens would be easy to add on, and they cost basically nothing ($20 or so). You could even add an infrared remote if you felt like it pretty easily. (be about $20 or so for the HSDL-1001 & 7001 pair, and then need to implement a UART).
If you can do the work, and put in the time, you can easily make it for far less than $250, and far less than $150, as well, with basically any features you want.
Nope, not unless he works for Xilinx, as his name is silkscreened on the board. He bought the FPGA from Xilinx, had the board made at a cheap board house (the cheapest, from what I've seen... though they don't look that bad), and soldered them himself.
Done well reflow soldering kicks ass (hence the reason why there's a very advanced toaster oven sitting about 10 feet behind me) but the problem is that you really do want the "very advanced" toaster oven if you're going to do this - one with a temperature profile that's settable (or at least one that's designed to solder, rather than cook). With an incorrect profile, the part will probably misregister and yank to the place where the solder happened to be the most. So I really wouldn't recommend homebrew reflow soldering with fine-pitch components - it won't work well.
Hell, hot air soldering fine-pitch components doesn't work that well either. Fine pitch is just not easy without a fine hand and a microscope.
... and what do you know, he did go through Olimex for the PCBs. OK, so apparently they don't suck. $26 for double-layer soldermask and silk is completely insane. Granted it doesn't include shipping, but who cares? It's practically free.
Soldering flat pack devices is a bit of a pain, but there are a few tricks that you can use to get it to work. The solder paste/toaster oven trick is a poor man's reflow oven, and I wouldn't recommend it, as especially with flat packs, you'll have as much problems getting the thing registered correctly as you would with a fine tip soldering iron.
Best way to do this is lots of solder, and lots of flux. You can cheat as well if you want - get it registered correctly (do the middles of each side) and then literally bathe each side in solder. Don't worry about bridging - you just want every joint made. Then go back with solder wick and very carefully remove the solder inbetween the pins. It's crufty, and you need to be a bit careful, but it is very quick and it does work.
BTW, circuit boards are cheap through the right vendors. CustomPCB for instance is $50 for a single-layer solder-masked circuit board (4 of them, to be specific) and Olimex (who I've never gone through) is even cheaper - $26 for double-layer with soldermask & silk.
Bizarrely enough, the answer to that is most likely "yes", because the chromosphere thermalizes gamma radiation from the core. Though, somehow, my guess is that the "chromosphere shoved off of a star" model for gamma ray bursts wouldn't work that well. Then again, who knows, theorists can do wondrous things with models...
And if you remember relativity, when an object is travelling near the speed of light, the mass increases. So the theory at least makes sense. Here's another thing to ponder. If an object the size of the sun suddenly acquired the 99x its mass, would it not either collapse upon itself, or expand rapidly, nova, and the core would collapse upon itself, causing the same result, a singularity, with a small event horizon. And it will be this singularity that will collide with Earth, ripping through it in a fraction of a second, and the sudden, combined gravitational effect on earth will cause it to very suddenly pull out of it's orbit toward the origninal center of gravity of the sun, with a nice city sized hole carved through it.
point of note: a "nova" is what happens when fresh yummy hydrogen falls on a white dwarf. Boom! A "supernova" is what you were talking about. Confusing the two is a little dangerous, because they're two completely different processes.
Depends on the mechanism of acceleration, really. If it's merely "moving" at a Lorentz factor of 100, then no, of course not, because all you did was Lorentz boost the system, which you can always do. In the Sun's rest frame, it's fine still, of course. In the boosted frame, it's also incredibly flattened (like a pancake - by a factor of 100, no less) but amazingly enough, you can still work out hydrostatic equilibrium for it, and determine that yes, it is still in equilibrium, and not going to blow up. Beauty of relativity - laws of physics are Lorentz boost invariant.
However, if you're actually accelerating the thing, now that's a different story. You (still) won't make it go supernova, because you're NOT actually increasing the number of particles inside it, and that's what breaks hydrostatic equilibrium - pressure generated versus gravity, and BOTH of those change in the boosted frame - but you WILL screw it up really badly by sending pressure bubbles through the whole thing. Since the Sun isn't a rigid body, you'll probably strip the chromosphere right off of it, and leave the core bare. This, however, won't due much except really really confuse distant astronomers.
First, most stars are binaries, not one out of ten. The figure is something like 2/3, I think. Don't quote me on that, it's from a class about 5 years ago.
Second, tidal forces on Earth do NOT cause our magnetic field. Take the Moon, for example - it stresses us tidally, and we stress the hell out of it tidally (hence the reason that it faces us). But it doesn't have a magnetic field at all. Our magnetic field is caused by our high rotation and due to the fact that we still have a molten core. Mars rotates quickly, but does not have a molten core, so no magnetic field. Venus has a molten core, but doesn't rotate, so it doesn't have a magnetic field. Mercury has a magnetic field, though it's weak, and it is most likely due to the fact that the planet has no crust - it's fundamentally just the core of a planet that cooled and stopped spinning, so its magnetic field was frozen in (it's a giant ferromagnet).
Third, the Earth/Moon is not a binary: the barycenter of rotation is inside the Earth. The Moon orbits us. We don't orbit the Moon. With Pluto/Charon, that's not the case - the barycenter of rotation is in empty space. Pluto orbits empty space, and Charon orbits empty space. That's a binary. We're a planet/satellite system.
Last points: the axis tilt stuff IS right. Search around a bit - it's recent (1995 or so, if memory serves) but take a look at Mars, for instance, which (lacking a moon) swings between 15 and 35 degrees. And the solar wind would not strip away atmosphere - it would destroy the ozone layer, and ionize water, but it would not "strip away" atmosphere. That's ridiculous - the solar wind is almost all protons, which wouldn't have any chance of knocking a nitrogen nucleus out of Earth's atmosphere, and if it did, there aren't enough particles to make a dent anyway.
Gravitational perturbations from other planets and tidal effects. Without one strong dominant tidal force (year round) Earth's axis would slowly precess and move around.
Look it up: just google for earth axis moon stabilize, and there are about a hundred links on it.
Incidentally, the axis of rotation does shift - with a period of about 41,000 years currently. That's "suddenly" on a geological/evolutionary scale.
Actually, he is correct - the tidal influence of the Moon is what keeps Earth's axis stable. Without the Moon, the other planets in the solar system would tug slightly on Earth as it rotates and cause it to "wobble" on its axis.
The reason for this is rather simple: the Moon is the largest contributor to the tidal forces acting on the Earth - all the other tidal effects are merely corrections on the Moon's, and the Moon forces a steady small oscillation (precession). Earth's angular momentum actually isn't large enough to keep its axis stable - if it were significantly faster or slower, it would be stable. If faster, the torque required to change the axis would be huge, and if significantly slower, the rotational tidal effects would be negligible.
Mars, for instance, spins quite fast (due to repeated asteroid collisions) and has a very unstable axis - it swings between 15 and 35 degrees, with longer period oscillations between 0 and 60 degrees.
Venus is virtually tidally locked, but does have a slight rotation (in a tidal resonance with Earth) but spins so slow that its axis is stable. Ditto with Mercury.
There have been several (AimSTAR for one) serious proposals to NASA for interstellar probes that travel at significant fractions of lightspeed (0.3c in the proposal I saw). At that speed it would take only about 12 years to reach Alpha Centauri, and only around 30 or so years to reach a good number of stars. Definitely doable. (Most of these were ultralight antimatter fueled probes, and NASA didn't pick them up.)
The other thing to remember is that time dilates near light speed, so for the object that's traveling, faster than light speed is easy. How fast do you want to get to Epsilon Eridani (a sunlike planet 10 light years away with a known Jovian-like planet)? 5 years? No problem. Travel at about 0.7c. 1 year? 0.95c. It will still take 10 years (or so) according to Earth, but not to the people on board.
Also, a little more offbeat, yes, but faster than light travel is not impossible - just "likely to be impossible". Relativity is what says "FTL travel is impossible" and general relativity allows for multiply connected spacetime (wormholes) which would let you "effectively" move faster than the speed of light, and also the "moving walkway" effect (the Alcubierre effect) - that is, even though matter has a "maximum speed limit", space itself does not, so if you could move space around, you could drag yourself faster than the speed of light.
Anyway, interstellar travel isn't impossible. It isn't even that difficult. It's just an engineering problem. Give it time.
I'm pretty sure that all life needs water. You may be thinking of extremophiles, which live in conditions that are near boiling of water, etc, but they still need water. Water is life. It's not just thinking inside the box - it's basic physics. Water is a very strong simple dipole (hydrogen + carbon is not, hydrogen + nitrogen is too weak, and hydrogen + fluorine is not: ditto for H+Li, H+B, etc.) and dipoles are needed to form complex chemistries that wouldn't exist elsewhere - weak bonds, etc. Even things that live in completely arid conditions need water - they covet it like mad. That's because water allows certain reactions to occur that would never occur, and it rips ionic compounds apart. You'd never get sodium chloride apart without a dipolar compound, and a strong one at that, which means you'd never get sodium or chloride into your chemistry, which means less variation.
"Arid" and "extreme temperatures/pressures" don't equal "no water" - if water can't exist, you don't have life - at least, not life based on chemistry, and not prolific life. Try forming a chemistry based on some wacko chemistry and you'll probably have the simple problem of not enough of the atoms exist. We're based on H, and CNO. If you ignore helium and neon (which are not chemically reactive) those are the four most abundant elements in the Universe. That's not being anthrocentric. It's cosmology. I doubt it's coincidence.
Here for more.
An oxygen atmosphere is looked for simply because it can't exist unless it's being sustained by living organisms. It's a marker signature for life.
That's not true. Venus is tidally locked, and Earth would've been tidally locked as well, but we got thwacked by a very large object (the Moon). Objects that are close in do lose their rotational velocity due to tidal slowing, but depending on the situation, that could take either a very long time, or be disrupted due to another planet.
Venus, for instance, is not perfectly tidally locked - it's in a resonance with Earth, which is why its day is not completely equal to its year. Ditto with Mercury, which has a 2:3 resonance.
If you consider the tidal slowing of the Moon, it's still extremely slow: the day is increasing by about 23 seconds per million years. The Moon and the Earth will be tidally locked after about tens of billions of years.