"What if I distributed a bunch of mini printing presses that, when you pressed a button, produced a perfect copy of this year's best selling novel?"
Depends. Where do those mini printing presses get their data from to print the novel? If its already in there (in the machine), then clearly you are already violating copyright, since the information has been copied and distributed along with the presses.
If it's not, and the presses get their copy from the internet/site and did so without authorization, then it would be that site that violates copyright, since (duh) it is copying and distributing it copyrighted work without authorization.
So... what exactly was your point?
One *might* make laws against 'facilitating' copyright infringement - and some countries have done so - even when it concerns downloading stuff, but it *ISN'T* considered 'downloading' nor 'copyright infringement' to give a reference to something. But something that is in your RAM/cache isn't considered to be copyright-infringement (at least in the EU).
So, in your example of presses, as long as they don't contain the information in the form of a copy it can't possibly be considered copyright infringement. It may go against a law that deals with *facilitating* copyright infringement, if such a law exists in your country, but it is not a copyright-violation on itself. Note, btw, that not every copy is an illegal copyright violation, as the VHS copying (and laws) have established. (ah, does the youth even know what VHS is anymore).
It seems strange that one is so willing to lose all the rights one wants had. Must be defeatism. We're slowly moving into a direction where ALL copying, and now even referring to material that might or might not be copy-infringed is considered a copyright violation (and thus illegal) on itself.
The reason is obvious: companies and business have much too much sway with politicians who make the laws. They have far more clout (and money, and lobbying groups) than ordinary citizens have, and thus we're always getting the short end of the stick.
Copyright should be restricted to the lifetime of the author (for natural persons) or 40 years max (for non-natural legal entities as copyright-owners). Software shouldn't be patentable, just like business ideas and algebraic formula's shouldn't.
We've just been swinging far too much in one direction (aka, corporation-interests) instead of making a balance of things. After all, IP-rights are de facto monopolies, granted by the state. And the state, in a democracy, are the citizens. So if those very, very long duration and strict IP-rights are not to be benefit of the populace anymore, we should get rid of it, at least in its current form.
No. It *IS* insane. And not consistent with normal copyright at all. Normal copyright(infringement) has always been about copying the original work (without authorization), not about giving a *reference* where you can find material that could or could not infringe copyright.
For instance, a book is copyrighted. I can't copy a book. I can, however, indicate where you can *find* that book. That is, and has never been, copyright-infringement - EVEN if it would turn out the book I give the place and direction to, would turn out to be counterfeit and an illegal copy. Then still my reference/address to it would not be considered copyright-infringement on itself. going that route is asinine. Then you could as well claim that describing where some illegal activity takes place (like: "In that dancing club drugs are traded and bought") would make you criminally liable for drugstrafficing as well. Because, you know: referencing to something is the same as doing it, apparently. That would be great news to newsanchors, I'm sure.
Of course it wouldn't. And it certainly shouldn't.
The only way this would be possible is if you had copyrighted *the address* itself. But while you can copyright a name (brand), you can not copyright a reference - this falls in the same space as recipes or any other reference or listing.
And in this case, that's not even the contention. Playboy didn't claim copyright of the link itself, but of the images it linked to. Which is normal, because the link was to another site/domain, and not made by them, so they can't assert copyright over a link someone else made. No, they only have copyright over the images. and they argued that linking to something they hold copyright over is a copyright infringement on itself. which it clearly isn't, yet the court more or less got into that absurd reasoning. And that's why it's bunkers and should be repealed.
you're not making much sense. The parent poster was arguing (correctly, imho) that giving *an address* to something is not the same as making a copy of the object itself. The latter is copyright, the former not.
I fail to see how anything you said here has any relevance to refute this argument. When you destroy a building and the plot of land is left, that plot of land has no address anymore, so both the building and the address is gone. So what, exactly, was your point? You seem to imply something is a copyright-violation depending on how easy the original object can be destroyed or moved. But that's not the case at all. Copyright (and the violation of it) has to do with... copying the original work (without authoriastion). That's it. It has nothing to do with how fast you can delete or move the object itself.
Let's say I give a reference to a book, for instance, where I give the address, name, shelf, row, and booknumber, etc., in a library or shop or whatever. Now, the book is surely copyrighted. It also is fairly trivial to remove, destroy or change the place of that book. But what has that to do with anything? Is it now not a copyright-infringement, because it can be destroyed a lot faster than a building? Where do you get those ideas?
And it doesn't matter anyhow, because you're giving the precise spot/place where you can find it, you do NOT give the actual object (or a copy of it). The same goes for your example of copyrighted buildings. So what? Even if the buildings are copyrighted, *the address* to those buildings are not. The moment one declares that even giving the address to something is the same as actually copying the object itself, then all and every indication, address or reference becomes a possible (il)legal infringement. As the parent poster points out, this would be an absurd ruling and an unfounded stretch of what copyright entails, and have strong ramifications on free speech, even.
In essence it's quite simple: a link or address is NOT a copy of the work itself. Ergo, it's shouldn't be considered a copyright-infringement.
Hmm. I think you're not quite seeing what my point was. Or maybe you do, but we're talking about other possible applications. That the casimir affect is real, is not something science doubts, since it has been proven by numerous experiments. They even managed to get photons out of it. http://physicsworld.com/cws/ar...
However, what is impossible is getting 'free' energy out of it. Since vacuum energy is in its lowest state, you can not *derive* energy out of it, at least, not while putting much more energy in it in the first place. In short, it's completely useless as a free-energy machine, a perpetuum mobile, an over-unity device, or a reactionless drive like the EMdrive, etc.
Lol. Well, I don't know. I mean, yes, they're both wrong as far as completely accurate predictions are concerned. At least that stance is consistent, I would agree.
But in normal usage, we consider a law to be valid as long as its predictive value is reasonably good, within its domain.
And it's also clear that something that is antithetical to it will not appear (unless our observations of the last 400 years are worth nothing). I would agree NG is only fairly good (contrary to some claims, most probes still use NG to navigate in our solarsystem, except when very accurate, precise movements and times are necessary, like with GPS-satellites), and GR is exceptionally good, covering about everything to an astonisching degree and accuracy in its domain of spacetime, and only faltering in the most extreme circumstances.
It's clear a GUT will be even more precise, combining the domain of QM and GR into one, and no doubt being even far more correct, especially (or at least, most noticable) in those extreme conditions.
And in any case, whether using NG, GR or QM, the EM-drive still is bullocks.;-)
Well... I can see the use in testing it, but it DOES seem rather foolish to do it with the actual satellite on board. I mean, that really saves nothing. Why not do the exact same test with the exact same rocket (so that, indeed, you can test the whole system) with a dummy load?
It will give you all the same parameters and data to see if your rocket works and has no structural failures, but wouldn't entail the loss of the actual satellite (and dito raise in insurance they'll suffer) by the loss of a 2 billion-worth satellite.
I'm not agreeing with those such a 'wet test' isn't useful to do in front, but it doesn't seem a good cost-benefit analysis, nor a good reason to take the risk of losing the satellite. I mean: if everything went well, it would have went well for the launch too, and if something borks, you'll lose the satellite anyhow, whether it's with this test or with the actual launch.
In comparison, if you do it with a dummy load, it's like this: if everything goes well, it will go well with the satellite too, and if something goes wrong, you'll only lose a dummy-load, not something worth 2 billion.
In both cases you get the necessary data and assurance that nothing big went wrong (or data on what went wrong). But in the latter case you take a lot less risk with your customers' expensive goods, your reputation, and the possibility of your insurance getting raised.
So... I understand the test, but I don't understand why they test it *this way*.
Well, I've already responded on the similar post you made, so I'm not going to reply twice and saying sorry. Or...maybe I am.;-)
Look, to make clear: no-one (well, at least not me) is claiming the GR doesn't do a better job at giving more accurate predictions. What I did say was, the NG still works as a special case even within GR, and has still the same validity and predictive power it had, as long as you limit it to its own domain and a specific, given frame of reference. People giving examples where NG fails in another domain and frame of reference didn't read what I wrote. Also, people saying a law is invalid because its an approximation, yet consider GR a valid law, don't seem to realise ALL laws are approximations.
Well, if we're going to be pedantic, let me replace the word 'wrong' with 'inaccurate', because ultimately, that's what it boils down to the argumentation you provide. And in that case:
No, NG is actually more than a 'tiny bit' inaccurate. It's *pretty* good, but not *very* good, and even the orbit Mercury can't be exactly predicted.
However, as I stated numerous times now, if one takes the position NG is 'wrong' or 'broken', because it lacks accuracy unless in a limited domain and frame of reference, then GR is 'wrong' and 'broken' as well. We already knows it fails to predict with any accuracy in extreme situations, like in the inside of a singularity. there, it in effect, 'brakes down' and has no predictive power anymore.
Yes, GR is *more* accurate than NG, but it's not perfectly accurate neither, and certainly not in all domains, as QM has shown (that's why we know we're still not there yet and search for a GUT).
The question thus, is not if the predictions a law has or makes is perfect to be considered to be a working or correct law, but IF it has predictive qualities (in its own domain). Clearly, the NG has that to some extend. GR has that even more and in a broader domain. Neither are perfect. ALL laws are approximations, thus claiming the NG is not valid anymore because it's a approximation does not make sense if - following that same argument - not all laws are deemed invalid.
This does not mean the preconceptions and premises used to come to that law were all correct - clearly some if it was not, but it means the *formulation* (aka, the equations) had predictive qualities that are still not contradicted by the new law, *provided* you limit it to its own domain and a specific frame of reference. That, ultimately, is what it boils down to when we call a theory or law 'working'. Even when it's not working perfectly, it's still working, and it's still there in some form in the new law. If we ever find a GUT, that will no doubt be even more accurate than GR, especially in extreme conditions, like in the singularity of a black hole, where our current laws break down. But that will NOT mean GR suddenly stops working and has no predictive capabilities anymore. No, it will be as valid as before, only LESS accurate than a GUT. And seen the strong observational worth of it, no doubt it, in turn, will be incorporated in a GUT as a special case, still valid within *its* domain and frame of reference.
Me? It's you who gave that example, not me. Yes, I get that you mean it to be in an analogy, but it's a false analogy, which makes it basically a straw man fallacy. So I'm not sure how or why I should defend a pôsition that wasn't mine from the start.
I clearly said it has to be seen in its own domain, and it has to have predictive powers.
Ok... so what domain did Aristotles law of gravity petain? And in that frame of reference, what was the predictive power of his theory? Well - dixit yourself - that heavier objects fall faster than slow ones. And is that correct? No. IF his frame of reference would have been that VOLUME of an object matters when objects fall down in an *atmosphere* THEN it would have had *some* predictive value. But that was not the contention. The measure of something being 'valid' or 'working', thus, is merely dependent on the predictive powers it has, within it's domain.
Which, with NG, was pretty good. Not VERY good, but it had clearly predictive power, within its domain. With GR, it was even better and in a broader domain. And a GT will even be better and more accurate still. But it won't mean that GR lost its validity and will be 'broken' once a GUT will be invented. No, it will remain as valid in its domain as before.
I've said this before to people arguing it's 'broken' because NG wasn't accurate, argue from an irrelevant standpoint, since ALL laws are approximations, and ALL laws, including GR *ARE NOT COMPLETELY CORRECT* neither. So, if that is the contention, that NG is broken because it wasn't correct (indeed, as your example of Mercury indicates), then the obvious conclusion is, that GR is broken as well. Yes, it's far more correct, and it depicts what and where Mercury will be, but it can't tell what happens in the singularity of a black hole, for instance. It can't predict well - or not at all, in fact - in domains that entail very high densities or energies.
So using the 'not being able to predict perfectly' as a means to say a law is invalid, makes all laws invalid.
Nobody is denying the GR didn't supersede NG, and isn't much better. I'm merely saying that a predictive power a law has or had, isn't suddenly gone when something else comes along which is better at it. In its domain, it still has the same predictive power, and that power doesn't need to be perfect to be considered 'valid' (or the opposite, 'broken'), otherwise no laws would be valid (and all are broken). There is no denying NG had, and still has, predictive powers. Those are less precise than that of the GR, for sure, but it doesn't mean NG has no predictive value anymore. Just like a GUT will not overturn and make GR invalid in its own domain, because it is more precise. If anything, a GUT will simply incorporate GR as a special case, just like GR did with NG.
Actually, a lot of space-faring and navigation of probes still use NG, and only when more precision is required (like with GPS-satellites, indeed) do they switch to GR.
The domain was always limited, only one didn't know, which is why it was more incorrect than GR outside a specific frame of reference (as is shown by it still being correct as a special case incorporated in GR). Sure, it's a big change. But not because NG isn't valid anymore in the domain it has always been valid, but because GR does a better job at it (aka, has more predictive power in more domains).
Again and again I see people argument that NG is broken because it's not accurate. But with that line of reasoning, everything is broken, because, for sure, the GR ALSO is not completely accurate and correct. Just like NG wasn't. It is BETTER in predicting, and, true, that's a big change. But it doesn't change the correctnes of Ng in it's own domain, with it's own level of prediction. Idem; if and when we ever have a GUT, that GUT will NOT suddenly make GR invalid and broken. No, GR will still be as correct and good as it ever was IN ITS DOMAIN. Only, the GUT will still be better, especially in extreme circumstances where current laws break down, like in the singularity of a black hole.
Is GR now broken because a GUT is even more correct? Of course not: it will remain as valid as it was before.
The casimir effect exists, yes. You can not derive free energy from it or any other "zero-pointenergy-tapping-machine", though. See http://www.csicop.org/si/show/...
You'll note that flat Earth and geocentrism is not among them.
As for your last sentence: I just gave you the equations in one of my former posts that prove NG is still valid *within its domain and a specific frame of reference*. The GR *incorporated* it as a special case, thus, but NG remains as correct, or incorrect, as it has before. Just as the GR itself is. If your stance is that because it's an approximation and thus 'incorrect', then all laws are incorrect, because all laws are approximations. Which makes any debate over what is broken and not meaningless. Since I don't engage in meaningless debates, what is meant when talking about something being a law, and it being valid: it pertains to being valid WITHIN itts own domain and within a frame of reference. That's why I explicitly mentioned it as such in my very first post in this thread, yet some people say I'm wrong and then give an argument which is *outside* the domain of that law. It's like saying 'that horse is the fastest living being on that horse-track' and then trying to counter it with 'But that car is much much faster on the road." that's inconsequential and irrelevant. No doubt an airplane flying in the air will still be faster, just like a GUT will still be 'more correct' in more domains than even GR.
What 'works' and what is 'broken' is merely dependent on what frame of reference you use, and if it has predictive power within that frame. And the NG has that. The GR has it more and better. But that is inconsequential and irrelevant to the question if NG still has predictive value in its own domain.
All approximations (and since all laws are approximations; all laws) assume propositions that are incorrect. It only depends on what domain you make it applicable, and in what frame of reference.
I thought I addressed that specifically, in my last post. There is no such thing as being 'correct', if you take it out its own domain. It's not merely a case of misapplication: even when you apply NG or GR completely and fully correctly, it still are approximations, and thus, will always be incorrect in some domain. What is meant by 'valid', thus (or 'broken' as an opposite) is that it's not valid anymore WITHIN their own domain (and consequently, also has no predictive value anymore). But NG just remains as valid in its own domain, provided you use the appropriate frame of reference. Yes, it's not completely *accurate* in describing it, but neither is GR completely accurate, and it's doubtful we'll ever find a 'completely accurate' approximation (at least, with absolute certainty), even if and when we develop a GUT.
The difference thus, between it being a law or not, is not whether it's fully correct or not, since none are. But I'm repeating myself. IF you deem GR a law, then so should you consider NG a law. IF your contention is that NG isn't a law because it's incorrect and an approximation, than so is GR.
And whenever a new law would be discovered, say, in a 'sapcetimemultidimension'-framework or whatever, that new law would be more correct than GR, but it would also *incorporate* it as a special case, just like the GR did with NG. What it *won't* do, is being antithetic to all that preceded and suddenly show GR is broken and holds no truth nor any predictive power anymore, not even in it's own domain. Ergo; being valid/broken should always be seen within a certain frame of reference/domain, thus, or else you can simply deduce all laws are broken.
Wait, wait... decide on how you are going to counter and argument. Do you refute the formulations on that page because it's a 'blog'? Or do you content it's correct but feel it does not address your points?
As it looks now, you're trying to claim both. Maybe you should start with one, because there is no use in going further at your second objection if you claim the first?
Blown away by my copy-paste? Dude, I *told* you it was a copy-paste since you couldn't be bothered to read the link. You fail at your fail, thus.
So, tell me, not-blown-away-guy, to what point in the equations given do you object? Where do you see an error, exactly?
In the wise decision you agree with it, yet feel it's not adressing your point about newtons' gravity not addressing issues in the spacetime continuum....
Uhuh. Please go back to my former post which you commented on. Note the last sentence. I'll quote: "It is *incorporated* into GR as a special case, but within its domain and a given framework, it remains valid."
What did you not understand about 'it's domain' and 'given framework'? As said, but I'll repeat it especially for you: the GR did NOT invalidate Newtons' gravity, as the equations show (btw, if you don't believe 'the blog', feel free to roam the internet; other physicists have done exactly the same, with the same result.) The GR, however, is also applicable in more domains (to be specific, in the context of spacetime, whereas space and time are treated as independent entities for Newtons' gravity theory). this means - as said - GR *incorporates* it, since it's part of it in a specific framework, while it itself is not limited to that framework. That's why examples that deal with effects of spacetime are the domain of GR, not of of Newtons' Gravity. Aka: it's not its domain, nor its framework.
It means, not that Newtons' gravity was incorrect, but that GR was *more* correct (aka, addressing it better and in a more encompassing domain).
Also, you make no sense, when you apply your reasoning consistently. You seem to imply you consider the GR a 'law', and NG not. The reason for this, is, you say, because it's merely an approximation. However, claiming it means it was broken, because it was 'an approximation at best', immediately means the GR is broken too, since that is an approximation too. In fact, all laws are broken, then. There is no sense in debating what is broken and what not, if everything is broken, and if you consider approximations an indication of being broken, then GR definitely is broken too. Yes, it's more correct, but it's not correct in all domains neither, as we know since it breaks down in specific circumstances, like within a singularity of a black hole.
So, unless you mistakenly think the GR isn't an approximation neither, you're not making sense.
They are, however, both right within their own domain, and GR didn't invalidate NG.
Sure, here you go, since you couldn't be bothered to check the link:
We will demonstrate that the Einstein Field Equations reduce to Newton's Law of Gravity in the case of a weak field and slow-motion of a particle (v less than the speed of light, c).
As we have already seen, Newton's Gravitation Law can be written as
(1) 2 = 4G, Equation (16) in Newton's Law of Gravity.
In free-fall, a particle satisfies,
(2) d2x/dt2 = F/m= –, Equations (4),(15) in Newton's Law of Gravity.
In tensor notation, this is written as,
(3),ii 4G
(4) d2x/dt2 –,i
Corresponding to (1) in General Relativity is the Einstein Field Equations, which can be written in the trace-reverse form,
(5) R = (8G/c4)[T – ½Tg]
And corresponding to (2), is the geodesic equation,
(6) d2x/d2 = –(dx/d)(dx/d)
Our task is to show that (5) will reduce to (1) in low gravity, low velocity.
The first approximation we make is that the particle is moving at velocity near zero,
(7)(dx/d) (dt/d,0,0,0)
The only non-zero term for the 's in (6) will be =i, = =0. The equation becomes,
(8) d2x/d2 = –i00(dx0/d)(dx0/d)
Or
(9) d2x/d2 = –i00(dt/d)(dt/d), (x0 =t)
But by the chain rule of calculus,
(10) d2x/d2 = (dt/d)(dt/d)d2x/dt2
Therefore,
(11) d2x/dt2 = –i00
Equation (4) and (11) yields,
(12),i = i00
Using the Christoffel symbols of the second kind ( Torsion =0 in GR),
(13) = ½ g(g, + g, – g,)
Again setting =i, = =0, equation (12) becomes,
(14),i = ½ gi(g0,0 + g0,0 – g00,)
Since the time derivative of the metric is zero (Einstein Equivalence Principle), the only surviving term is = i. Then,
(15),i = ½ gii(– g00,i)= (–½g00,i)
A solution is,
(16) g00 = – c2 – 2
Turning to the Einstein Field Equations (5), and from (16), we only need the time-time equation, = = 0
(17) R00 = (8G/c4)[T00 – ½Tg00]
But
(18) T00 = c4 and T = g00T00 = (–1/c2)c4= –c2
Substituting (18) into (17), we get,
(19) R00 = 4G
Now to get to Newton's Law, equation (1), we need to work on the left-hand side of equation (19).
For that we use the definition of the Ricci tensor,
(20) R =/x –/x + –
From (19), = = 0,
(21) R00 = 00/x – 0/x0 + 00 – 00
In low gravity, the square of the 's is zero, and its time derivative is also zero. The only surviving term is,
Or, to be technical more correct: it only *appears* so to the crackpots, unintelligible idoits, and frauds who start to believe their own crap (or their gullible audience).
A reactionless drive, and the likelihood of it existing, can be compared to a perpetuum mobile. And there is a reason why patents are not granted for perpetuum mobile: it's because they don't work, and can't work.
The further discussion in this, thus, is whether one indeed 'need' to test it, seen the fact there is a limited budget, time and money, of scientific research. And if one deems it is, then why should you then also not claim the same for any perpetuum mobile or other crack-pot idea that pops up, to be researched?
It then is often argued 'because three tests have confirmed it', but that is exactly the crux of the matter: they didn't. There is as much proof or evidence or confirmation for that microwave-oven to be a reactionless device, then there is for any perpetuum mobile to be truly working, or for the 'thrust' to be due to dragon-magic.
My suggestion is: that those who are so convinced of it actually working start a kickstarter, and pay for it that way. Then, everyone is happy: the EM-believers, the sceptics, and the taxpayers.
Most physicists worth their salt realise how EXTREMELY (and I'm using an euphemism here) unlikely this is, and that's exactly why the scientific community at large doesn't jump on it: they have better things to do than waste their time and money on such a thing.
The inventor claims it can be explained by conventional (Newtonian) physics. That is utterly impossible. Newtonian laws (nor GR, *nor* classical QM for that matter) allow for such a thing.
At least White realised this, which is why he invented the "pushing against the virtual plasma" as an 'explanation'. Only problem is, there is no such virtual plasma, at least not in any known theoretical framework (or even an unknown but consistent one), and I didn't see White put one forward neither. So, basically, it has the same validity as saying 'it's pushing against dragon-magic'. It explains *nothing* at all, and thus can't be considered a valid explanation for the force measured neither.
Basically, for all intents and purposes, it IS a reaction-less drive, because it adheres to all the hallmarks of one. Claiming it is not doesn't change that fact. It would be akin to someone claiming the apple he throws and comes down is not due to gravity, but due to dragon-magic. Now, one might *CLAIM* it' not due to gravity, but it doesn't change the fact it IS still due to gravity. And until one comes up with proof or at least a consistent theory which is better than the explanation of gravity (aka, a falsifiable explanation of dragon-magic) such claims change nothing and are nonsensical statements.
To the defence of Tajmar, White, and maybe even the inventor: I don't think it are *deliberate* falsehoods. Contrary to say, Rossi with his scam of the E-cats. I don't think they are scamming or consciously deluding people. I've seen the presentation of White, and noted the critical stance of Tajmar: they don't seem to be deliberately confusing people into believing this story. Certainly not the latter. White might have been a bit too speculative, and the scoop-searching press and EM-fanfappers do the rest.
That said, one can rationally argue, or at least ask the question: with a limited budget for scientific research, if it's warranted to put taxpayers' money in such an extremely unlikely claim - without any theory nor decent experimental data to back it up. Even if it's only 500K, it could be better spend on some other scientific projects.
Or, alternatively, the fanfappers could make a kickstarter for it. I've asked this 6 times already, but: where *is* that kickstarter? What's keeping them from doing one? If everyone of the EM-believers would put their money where their mouth is, it would already have gotten 500K. Everyone happy.
I love new things. Only, I don't *believe* every new thing that comes along, until proof of it has been delivered.
And, as usual, you are reversing the burden of proof. And you know it. I have told you numerous, numerous times in the past, so you AR
I'm saying this in front, because it the typical thing people who are not to knowledgeable about the topic come up with. No, it's not been 'broken'. It is *incorporated* into GR as a special case, but within its domain and a given framework, it remains valid.
Is Skylon the only possible system using atmospheric air?
People seem to be a bit too much focussed on Skylon, although I admit I'm interested in it too, from a technical/technological standpoint.
The *principle* of the matter I just explained stands, though: that which you avoid taking with you as weight (the oxidiser) means you do not have to carry that weight, plus, you don't need to carry the weight of the fuel needed to carry the weight of the oxidiser, plus you do not need the weight of the fuel to lift the weight of the fuel that is needed to lift of the oxidiser, etc. There is a considerable reduction in weight, thus, and - as said - that matters for the useful payload, not for the reduction of *cost of the fuel* as some posts imply.
Whether or not the reduction of weight is always offset by the additional complexity and added weight (of the wings and engines, for instance), remains to be seen, but I would wager that totally depends on what system you use. Especially with non-SSTO systems (the Falcon is non SSTO too, after all) there are myriads of options one could use, and I doubt they'll all be 'worse' than the current Falcon-oxidiser-carying-system in regard of dry mass.
That said, if you're talking economically, and especially if you're talking specifically of Skylon, I think the reusable Falcon is far more viable. But just like all his competitors thought re-usability of a rocket was not (cost/benefit) worthwhile, and Elon Musk is (going to) proving them wrong, it might be that someone smart comes along, also with new ideas how to tackle things, and get affordable air-using systems going, which would be a new 'disruptive technology'. After all, the advantages - at least in principle - I explained in my former post remain valid and are physical sound. It's just a matter of finding a good approach that outpaces current systems.
That said, the point of a SSTO with airbreathing is not the *cost* of the fuel, but the weight-reduction itself, since the added weight that has been avoided in this way can be used for payload.
Even Elon Musk said it's not about the cost of the fuel, but the fact it impacts the useful weight of the payload.;-)
It's possible, thus, that for LEO an airbreathing spaceplane is more suited than a rocket, especially if that rocket isn't fully SSTO. You say it doesn't save 'much', but the oxidiser on a typical rocket makes out about a third of the total mass... I would call that pretty much.
Does not lay within it's technical capabilities and prowess, but with it's management skills and ability to create a community.
For years I've been a fan of ReactOS, actively participating and contributing to the community, albeit not in the form of a coder. Which, in the (still) current ReactOS mentality, is the only thing that counts for the brass, apparently. Testing ReactOS on a dedicated real-life machine (thus, not in VM), debugging, translating, making info-pages on their wikipedia: nothing really matters to the 'elite' of ReactOS. They just consider you some sort of fodder, and the moment you ask for a bit more transparency (on their financial side, for instance), or try to address the complete lack of community involvement, they bork (and bark) at you - and worse. Time and again I've tried to explain this in the past, that a successful project is NOT merely depended on the technical/coder side of things, but also how you establish a community, and try to involve people in your project. There were some half-baked trials at it, but those were mere lipservice, where it was always a consideration of a top-down approach, not a bottom-up way of seeing things.
Ergo; in the 20 years of their project, they have not succeeded in gathering 1/100th of the community that other projects like Linux have. Again and again I've pointed this out to them, but to no avail. They just refuse to see it, and only want things done strictly to their wishes, with their attitude of finding no other (real) importance to the project than 'code'. Which, granted, is an important part, but which will NOT get you a lively, engaging, and growing community - which is an absolute necessity for any open source project to know success. Eventually, since I kept hitting that nail, they got annoyed (not: they realised the error of their ways) and kicked me out too, the so many-th person who was a tester/sponsor/translator/helper of ReactOS they managed to drive away.
Whatever; so I went away, which is what they wanted. But what did it help them, then? Nothing at all. They view constructive criticism as a threat, not as an opportunity to better themselves and the project. They don't value anything someone does outside of their little constraints, and outside their preconceived notions as to what they see as important, yet have the mouth full of 'community-involvement'. Whatever you do, how many years you may have sponsored or helped out as a non-coder, you just are not counted as having done anything worthwhile. They have no inkling of an idea how to get a thriving community where you allow the bottom-up approach as well.
It's a sad thing to say, but the whole thing is run by people with overblown ego's, trying to protect their little turf and egotistical whims, ignoring anyone else, and being autistically elitist in wanting to decide virtually everything to the minute detail. Its only a community-project in name, but not in essence. And that's why, even after 20 years of operation, their project is just a small-scale project who - in comparison with other projects - has almost nothing to show for. They make some small technical progress year after year, that's true, but they fail to realise how much their ego-driven top-down approach has muffled the project to achieve the grandeur and support it could have had, had the top been more prone to some input from the people actually supporting it.
I've poured hundreds of dollars in it, and spend years on it helping them in my own way, only to kicked out when I pointed out their mistakes and lack of transparency. I still lie, the project, but I can not, in good conscience, support (most of) the people running that program/project. they've done it with me, as they've done it with dozens of people: it's no surprise, thus, that they're still at the small scale they are, without any community to speak off. They can't get any traction, because they kill off everything that would get them traction. There are some good coders under them, to be sure, but almost all of them lack the ma
Slashdot Mirror
"What if I distributed a bunch of mini printing presses that, when you pressed a button, produced a perfect copy of this year's best selling novel?"
Depends. Where do those mini printing presses get their data from to print the novel? If its already in there (in the machine), then clearly you are already violating copyright, since the information has been copied and distributed along with the presses.
If it's not, and the presses get their copy from the internet/site and did so without authorization, then it would be that site that violates copyright, since (duh) it is copying and distributing it copyrighted work without authorization.
So... what exactly was your point?
One *might* make laws against 'facilitating' copyright infringement - and some countries have done so - even when it concerns downloading stuff, but it *ISN'T* considered 'downloading' nor 'copyright infringement' to give a reference to something. But something that is in your RAM/cache isn't considered to be copyright-infringement (at least in the EU).
So, in your example of presses, as long as they don't contain the information in the form of a copy it can't possibly be considered copyright infringement. It may go against a law that deals with *facilitating* copyright infringement, if such a law exists in your country, but it is not a copyright-violation on itself. Note, btw, that not every copy is an illegal copyright violation, as the VHS copying (and laws) have established. (ah, does the youth even know what VHS is anymore).
It seems strange that one is so willing to lose all the rights one wants had. Must be defeatism. We're slowly moving into a direction where ALL copying, and now even referring to material that might or might not be copy-infringed is considered a copyright violation (and thus illegal) on itself.
The reason is obvious: companies and business have much too much sway with politicians who make the laws. They have far more clout (and money, and lobbying groups) than ordinary citizens have, and thus we're always getting the short end of the stick.
Copyright should be restricted to the lifetime of the author (for natural persons) or 40 years max (for non-natural legal entities as copyright-owners). Software shouldn't be patentable, just like business ideas and algebraic formula's shouldn't.
We've just been swinging far too much in one direction (aka, corporation-interests) instead of making a balance of things. After all, IP-rights are de facto monopolies, granted by the state. And the state, in a democracy, are the citizens. So if those very, very long duration and strict IP-rights are not to be benefit of the populace anymore, we should get rid of it, at least in its current form.
No. It *IS* insane. And not consistent with normal copyright at all. Normal copyright(infringement) has always been about copying the original work (without authorization), not about giving a *reference* where you can find material that could or could not infringe copyright.
For instance, a book is copyrighted. I can't copy a book. I can, however, indicate where you can *find* that book. That is, and has never been, copyright-infringement - EVEN if it would turn out the book I give the place and direction to, would turn out to be counterfeit and an illegal copy. Then still my reference/address to it would not be considered copyright-infringement on itself. going that route is asinine. Then you could as well claim that describing where some illegal activity takes place (like: "In that dancing club drugs are traded and bought") would make you criminally liable for drugstrafficing as well. Because, you know: referencing to something is the same as doing it, apparently. That would be great news to newsanchors, I'm sure.
It makes no sense whatsoever.
Of course it wouldn't. And it certainly shouldn't.
The only way this would be possible is if you had copyrighted *the address* itself. But while you can copyright a name (brand), you can not copyright a reference - this falls in the same space as recipes or any other reference or listing.
And in this case, that's not even the contention. Playboy didn't claim copyright of the link itself, but of the images it linked to. Which is normal, because the link was to another site/domain, and not made by them, so they can't assert copyright over a link someone else made. No, they only have copyright over the images. and they argued that linking to something they hold copyright over is a copyright infringement on itself. which it clearly isn't, yet the court more or less got into that absurd reasoning. And that's why it's bunkers and should be repealed.
you're not making much sense. The parent poster was arguing (correctly, imho) that giving *an address* to something is not the same as making a copy of the object itself. The latter is copyright, the former not.
I fail to see how anything you said here has any relevance to refute this argument. When you destroy a building and the plot of land is left, that plot of land has no address anymore, so both the building and the address is gone. So what, exactly, was your point? You seem to imply something is a copyright-violation depending on how easy the original object can be destroyed or moved. But that's not the case at all. Copyright (and the violation of it) has to do with... copying the original work (without authoriastion). That's it. It has nothing to do with how fast you can delete or move the object itself.
Let's say I give a reference to a book, for instance, where I give the address, name, shelf, row, and booknumber, etc., in a library or shop or whatever. Now, the book is surely copyrighted. It also is fairly trivial to remove, destroy or change the place of that book. But what has that to do with anything? Is it now not a copyright-infringement, because it can be destroyed a lot faster than a building? Where do you get those ideas?
And it doesn't matter anyhow, because you're giving the precise spot/place where you can find it, you do NOT give the actual object (or a copy of it). The same goes for your example of copyrighted buildings. So what? Even if the buildings are copyrighted, *the address* to those buildings are not. The moment one declares that even giving the address to something is the same as actually copying the object itself, then all and every indication, address or reference becomes a possible (il)legal infringement. As the parent poster points out, this would be an absurd ruling and an unfounded stretch of what copyright entails, and have strong ramifications on free speech, even.
In essence it's quite simple: a link or address is NOT a copy of the work itself. Ergo, it's shouldn't be considered a copyright-infringement.
Hmm. I think you're not quite seeing what my point was. Or maybe you do, but we're talking about other possible applications. That the casimir affect is real, is not something science doubts, since it has been proven by numerous experiments. They even managed to get photons out of it. http://physicsworld.com/cws/ar...
However, what is impossible is getting 'free' energy out of it. Since vacuum energy is in its lowest state, you can not *derive* energy out of it, at least, not while putting much more energy in it in the first place. In short, it's completely useless as a free-energy machine, a perpetuum mobile, an over-unity device, or a reactionless drive like the EMdrive, etc.
Lol. Well, I don't know. I mean, yes, they're both wrong as far as completely accurate predictions are concerned. At least that stance is consistent, I would agree.
But in normal usage, we consider a law to be valid as long as its predictive value is reasonably good, within its domain.
And it's also clear that something that is antithetical to it will not appear (unless our observations of the last 400 years are worth nothing). I would agree NG is only fairly good (contrary to some claims, most probes still use NG to navigate in our solarsystem, except when very accurate, precise movements and times are necessary, like with GPS-satellites), and GR is exceptionally good, covering about everything to an astonisching degree and accuracy in its domain of spacetime, and only faltering in the most extreme circumstances.
It's clear a GUT will be even more precise, combining the domain of QM and GR into one, and no doubt being even far more correct, especially (or at least, most noticable) in those extreme conditions.
And in any case, whether using NG, GR or QM, the EM-drive still is bullocks. ;-)
You DID read the page I linked to, yes?
Well... I can see the use in testing it, but it DOES seem rather foolish to do it with the actual satellite on board. I mean, that really saves nothing. Why not do the exact same test with the exact same rocket (so that, indeed, you can test the whole system) with a dummy load?
It will give you all the same parameters and data to see if your rocket works and has no structural failures, but wouldn't entail the loss of the actual satellite (and dito raise in insurance they'll suffer) by the loss of a 2 billion-worth satellite.
I'm not agreeing with those such a 'wet test' isn't useful to do in front, but it doesn't seem a good cost-benefit analysis, nor a good reason to take the risk of losing the satellite. I mean: if everything went well, it would have went well for the launch too, and if something borks, you'll lose the satellite anyhow, whether it's with this test or with the actual launch.
In comparison, if you do it with a dummy load, it's like this: if everything goes well, it will go well with the satellite too, and if something goes wrong, you'll only lose a dummy-load, not something worth 2 billion.
In both cases you get the necessary data and assurance that nothing big went wrong (or data on what went wrong). But in the latter case you take a lot less risk with your customers' expensive goods, your reputation, and the possibility of your insurance getting raised.
So... I understand the test, but I don't understand why they test it *this way*.
I had a friend of a friend who knew someone who worked at NASA cleaning the toilets there, and she said people saying what you said were wrong.
So, there you have it.
Well, I've already responded on the similar post you made, so I'm not going to reply twice and saying sorry. Or...maybe I am. ;-)
Look, to make clear: no-one (well, at least not me) is claiming the GR doesn't do a better job at giving more accurate predictions. What I did say was, the NG still works as a special case even within GR, and has still the same validity and predictive power it had, as long as you limit it to its own domain and a specific, given frame of reference. People giving examples where NG fails in another domain and frame of reference didn't read what I wrote. Also, people saying a law is invalid because its an approximation, yet consider GR a valid law, don't seem to realise ALL laws are approximations.
Well, if we're going to be pedantic, let me replace the word 'wrong' with 'inaccurate', because ultimately, that's what it boils down to the argumentation you provide. And in that case:
No, NG is actually more than a 'tiny bit' inaccurate. It's *pretty* good, but not *very* good, and even the orbit Mercury can't be exactly predicted.
However, as I stated numerous times now, if one takes the position NG is 'wrong' or 'broken', because it lacks accuracy unless in a limited domain and frame of reference, then GR is 'wrong' and 'broken' as well. We already knows it fails to predict with any accuracy in extreme situations, like in the inside of a singularity. there, it in effect, 'brakes down' and has no predictive power anymore.
Yes, GR is *more* accurate than NG, but it's not perfectly accurate neither, and certainly not in all domains, as QM has shown (that's why we know we're still not there yet and search for a GUT).
The question thus, is not if the predictions a law has or makes is perfect to be considered to be a working or correct law, but IF it has predictive qualities (in its own domain). Clearly, the NG has that to some extend. GR has that even more and in a broader domain. Neither are perfect. ALL laws are approximations, thus claiming the NG is not valid anymore because it's a approximation does not make sense if - following that same argument - not all laws are deemed invalid.
This does not mean the preconceptions and premises used to come to that law were all correct - clearly some if it was not, but it means the *formulation* (aka, the equations) had predictive qualities that are still not contradicted by the new law, *provided* you limit it to its own domain and a specific frame of reference. That, ultimately, is what it boils down to when we call a theory or law 'working'. Even when it's not working perfectly, it's still working, and it's still there in some form in the new law. If we ever find a GUT, that will no doubt be even more accurate than GR, especially in extreme conditions, like in the singularity of a black hole, where our current laws break down. But that will NOT mean GR suddenly stops working and has no predictive capabilities anymore. No, it will be as valid as before, only LESS accurate than a GUT. And seen the strong observational worth of it, no doubt it, in turn, will be incorporated in a GUT as a special case, still valid within *its* domain and frame of reference.
"Do you see how stupid you sound now ?"
Me? It's you who gave that example, not me. Yes, I get that you mean it to be in an analogy, but it's a false analogy, which makes it basically a straw man fallacy. So I'm not sure how or why I should defend a pôsition that wasn't mine from the start.
I clearly said it has to be seen in its own domain, and it has to have predictive powers.
Ok... so what domain did Aristotles law of gravity petain? And in that frame of reference, what was the predictive power of his theory? Well - dixit yourself - that heavier objects fall faster than slow ones. And is that correct? No. IF his frame of reference would have been that VOLUME of an object matters when objects fall down in an *atmosphere* THEN it would have had *some* predictive value. But that was not the contention. The measure of something being 'valid' or 'working', thus, is merely dependent on the predictive powers it has, within it's domain.
Which, with NG, was pretty good. Not VERY good, but it had clearly predictive power, within its domain. With GR, it was even better and in a broader domain. And a GT will even be better and more accurate still. But it won't mean that GR lost its validity and will be 'broken' once a GUT will be invented. No, it will remain as valid in its domain as before.
I've said this before to people arguing it's 'broken' because NG wasn't accurate, argue from an irrelevant standpoint, since ALL laws are approximations, and ALL laws, including GR *ARE NOT COMPLETELY CORRECT* neither. So, if that is the contention, that NG is broken because it wasn't correct (indeed, as your example of Mercury indicates), then the obvious conclusion is, that GR is broken as well. Yes, it's far more correct, and it depicts what and where Mercury will be, but it can't tell what happens in the singularity of a black hole, for instance. It can't predict well - or not at all, in fact - in domains that entail very high densities or energies.
So using the 'not being able to predict perfectly' as a means to say a law is invalid, makes all laws invalid.
Nobody is denying the GR didn't supersede NG, and isn't much better. I'm merely saying that a predictive power a law has or had, isn't suddenly gone when something else comes along which is better at it. In its domain, it still has the same predictive power, and that power doesn't need to be perfect to be considered 'valid' (or the opposite, 'broken'), otherwise no laws would be valid (and all are broken). There is no denying NG had, and still has, predictive powers. Those are less precise than that of the GR, for sure, but it doesn't mean NG has no predictive value anymore. Just like a GUT will not overturn and make GR invalid in its own domain, because it is more precise. If anything, a GUT will simply incorporate GR as a special case, just like GR did with NG.
Actually, a lot of space-faring and navigation of probes still use NG, and only when more precision is required (like with GPS-satellites, indeed) do they switch to GR.
The domain was always limited, only one didn't know, which is why it was more incorrect than GR outside a specific frame of reference (as is shown by it still being correct as a special case incorporated in GR). Sure, it's a big change. But not because NG isn't valid anymore in the domain it has always been valid, but because GR does a better job at it (aka, has more predictive power in more domains).
Again and again I see people argument that NG is broken because it's not accurate. But with that line of reasoning, everything is broken, because, for sure, the GR ALSO is not completely accurate and correct. Just like NG wasn't. It is BETTER in predicting, and, true, that's a big change. But it doesn't change the correctnes of Ng in it's own domain, with it's own level of prediction. Idem; if and when we ever have a GUT, that GUT will NOT suddenly make GR invalid and broken. No, GR will still be as correct and good as it ever was IN ITS DOMAIN. Only, the GUT will still be better, especially in extreme circumstances where current laws break down, like in the singularity of a black hole.
Is GR now broken because a GUT is even more correct? Of course not: it will remain as valid as it was before.
I'm glad at least some sensible people are still on slashdot. One would begin to doubt after a while, with all the frothing nonsense flying around.
The casimir effect exists, yes. You can not derive free energy from it or any other "zero-pointenergy-tapping-machine", though. See http://www.csicop.org/si/show/...
Ermm, no. The earth being not flat and geocentrism being wrong were NOT ever basic natural laws. If you don't know what such laws entail, see http://www.iep.utm.edu/lawofna... , if you want examples, see http://physics.about.com/od/ph...
You'll note that flat Earth and geocentrism is not among them.
As for your last sentence: I just gave you the equations in one of my former posts that prove NG is still valid *within its domain and a specific frame of reference*. The GR *incorporated* it as a special case, thus, but NG remains as correct, or incorrect, as it has before. Just as the GR itself is. If your stance is that because it's an approximation and thus 'incorrect', then all laws are incorrect, because all laws are approximations. Which makes any debate over what is broken and not meaningless. Since I don't engage in meaningless debates, what is meant when talking about something being a law, and it being valid: it pertains to being valid WITHIN itts own domain and within a frame of reference. That's why I explicitly mentioned it as such in my very first post in this thread, yet some people say I'm wrong and then give an argument which is *outside* the domain of that law. It's like saying 'that horse is the fastest living being on that horse-track' and then trying to counter it with 'But that car is much much faster on the road." that's inconsequential and irrelevant. No doubt an airplane flying in the air will still be faster, just like a GUT will still be 'more correct' in more domains than even GR.
What 'works' and what is 'broken' is merely dependent on what frame of reference you use, and if it has predictive power within that frame. And the NG has that. The GR has it more and better. But that is inconsequential and irrelevant to the question if NG still has predictive value in its own domain.
All approximations (and since all laws are approximations; all laws) assume propositions that are incorrect. It only depends on what domain you make it applicable, and in what frame of reference.
I thought I addressed that specifically, in my last post. There is no such thing as being 'correct', if you take it out its own domain. It's not merely a case of misapplication: even when you apply NG or GR completely and fully correctly, it still are approximations, and thus, will always be incorrect in some domain. What is meant by 'valid', thus (or 'broken' as an opposite) is that it's not valid anymore WITHIN their own domain (and consequently, also has no predictive value anymore). But NG just remains as valid in its own domain, provided you use the appropriate frame of reference. Yes, it's not completely *accurate* in describing it, but neither is GR completely accurate, and it's doubtful we'll ever find a 'completely accurate' approximation (at least, with absolute certainty), even if and when we develop a GUT.
The difference thus, between it being a law or not, is not whether it's fully correct or not, since none are. But I'm repeating myself. IF you deem GR a law, then so should you consider NG a law. IF your contention is that NG isn't a law because it's incorrect and an approximation, than so is GR.
And whenever a new law would be discovered, say, in a 'sapcetimemultidimension'-framework or whatever, that new law would be more correct than GR, but it would also *incorporate* it as a special case, just like the GR did with NG. What it *won't* do, is being antithetic to all that preceded and suddenly show GR is broken and holds no truth nor any predictive power anymore, not even in it's own domain. Ergo; being valid/broken should always be seen within a certain frame of reference/domain, thus, or else you can simply deduce all laws are broken.
Wait, wait... decide on how you are going to counter and argument. Do you refute the formulations on that page because it's a 'blog'? Or do you content it's correct but feel it does not address your points?
As it looks now, you're trying to claim both. Maybe you should start with one, because there is no use in going further at your second objection if you claim the first?
Blown away by my copy-paste? Dude, I *told* you it was a copy-paste since you couldn't be bothered to read the link. You fail at your fail, thus.
So, tell me, not-blown-away-guy, to what point in the equations given do you object? Where do you see an error, exactly?
In the wise decision you agree with it, yet feel it's not adressing your point about newtons' gravity not addressing issues in the spacetime continuum. ...
Uhuh. Please go back to my former post which you commented on. Note the last sentence. I'll quote: "It is *incorporated* into GR as a special case, but within its domain and a given framework, it remains valid."
What did you not understand about 'it's domain' and 'given framework'? As said, but I'll repeat it especially for you: the GR did NOT invalidate Newtons' gravity, as the equations show (btw, if you don't believe 'the blog', feel free to roam the internet; other physicists have done exactly the same, with the same result.) The GR, however, is also applicable in more domains (to be specific, in the context of spacetime, whereas space and time are treated as independent entities for Newtons' gravity theory). this means - as said - GR *incorporates* it, since it's part of it in a specific framework, while it itself is not limited to that framework. That's why examples that deal with effects of spacetime are the domain of GR, not of of Newtons' Gravity. Aka: it's not its domain, nor its framework.
It means, not that Newtons' gravity was incorrect, but that GR was *more* correct (aka, addressing it better and in a more encompassing domain).
Also, you make no sense, when you apply your reasoning consistently. You seem to imply you consider the GR a 'law', and NG not. The reason for this, is, you say, because it's merely an approximation. However, claiming it means it was broken, because it was 'an approximation at best', immediately means the GR is broken too, since that is an approximation too. In fact, all laws are broken, then. There is no sense in debating what is broken and what not, if everything is broken, and if you consider approximations an indication of being broken, then GR definitely is broken too. Yes, it's more correct, but it's not correct in all domains neither, as we know since it breaks down in specific circumstances, like within a singularity of a black hole.
So, unless you mistakenly think the GR isn't an approximation neither, you're not making sense.
They are, however, both right within their own domain, and GR didn't invalidate NG.
Sure, here you go, since you couldn't be bothered to check the link:
We will demonstrate that the Einstein Field Equations reduce to Newton's Law of Gravity in the case of a weak field and slow-motion of a particle (v less than the speed of light, c).
As we have already seen, Newton's Gravitation Law can be written as
(1) 2 = 4G, Equation (16) in Newton's Law of Gravity.
In free-fall, a particle satisfies,
(2) d2x/dt2 = F/m= –, Equations (4),(15) in Newton's Law of Gravity.
In tensor notation, this is written as,
(3) ,ii 4G
(4) d2x/dt2 –,i
Corresponding to (1) in General Relativity is the Einstein Field Equations, which can be written in the trace-reverse form,
(5) R = (8G/c4)[T – ½Tg]
And corresponding to (2), is the geodesic equation,
(6) d2x/d2 = –(dx/d)(dx/d)
Our task is to show that (5) will reduce to (1) in low gravity, low velocity.
The first approximation we make is that the particle is moving at velocity near zero,
(7)(dx/d) (dt/d,0,0,0)
The only non-zero term for the 's in (6) will be =i, = =0. The equation becomes,
(8) d2x/d2 = –i00(dx0/d)(dx0/d)
Or
(9) d2x/d2 = –i00(dt/d)(dt/d), (x0 =t)
But by the chain rule of calculus,
(10) d2x/d2 = (dt/d)(dt/d)d2x/dt2
Therefore,
(11) d2x/dt2 = –i00
Equation (4) and (11) yields,
(12) ,i = i00
Using the Christoffel symbols of the second kind ( Torsion =0 in GR),
(13) = ½ g(g, + g, – g,)
Again setting =i, = =0, equation (12) becomes,
(14) ,i = ½ gi(g0,0 + g0,0 – g00,)
Since the time derivative of the metric is zero (Einstein Equivalence Principle), the only surviving term is = i. Then,
(15) ,i = ½ gii(– g00,i)= (–½g00,i)
A solution is,
(16) g00 = – c2 – 2
Turning to the Einstein Field Equations (5), and from (16), we only need the time-time equation, = = 0
(17) R00 = (8G/c4)[T00 – ½Tg00]
But
(18) T00 = c4 and T = g00T00 = (–1/c2)c4= –c2
Substituting (18) into (17), we get,
(19) R00 = 4G
Now to get to Newton's Law, equation (1), we need to work on the left-hand side of equation (19).
For that we use the definition of the Ricci tensor,
(20) R = /x – /x + –
From (19), = = 0,
(21) R00 = 00/x – 0/x0 + 00 – 00
In low gravity, the square of the 's is zero, and its time derivative is also zero. The only surviving term is,
(22) R00 = i00/xi i00,i
But from (12), repeating below,
(23) i00 = ,i
Take the derivative, and then use (23)
(24) i00,i = ,ii = R00
Using (19),
(25) ,ii 2 = 4G
And that is Newton's Law of Gravity (1).
" In fact it appears to exist"
No. It does not.
Or, to be technical more correct: it only *appears* so to the crackpots, unintelligible idoits, and frauds who start to believe their own crap (or their gullible audience).
A reactionless drive, and the likelihood of it existing, can be compared to a perpetuum mobile. And there is a reason why patents are not granted for perpetuum mobile: it's because they don't work, and can't work.
The further discussion in this, thus, is whether one indeed 'need' to test it, seen the fact there is a limited budget, time and money, of scientific research. And if one deems it is, then why should you then also not claim the same for any perpetuum mobile or other crack-pot idea that pops up, to be researched?
It then is often argued 'because three tests have confirmed it', but that is exactly the crux of the matter: they didn't. There is as much proof or evidence or confirmation for that microwave-oven to be a reactionless device, then there is for any perpetuum mobile to be truly working, or for the 'thrust' to be due to dragon-magic.
My suggestion is: that those who are so convinced of it actually working start a kickstarter, and pay for it that way. Then, everyone is happy: the EM-believers, the sceptics, and the taxpayers.
Most physicists worth their salt realise how EXTREMELY (and I'm using an euphemism here) unlikely this is, and that's exactly why the scientific community at large doesn't jump on it: they have better things to do than waste their time and money on such a thing.
The inventor claims it can be explained by conventional (Newtonian) physics. That is utterly impossible. Newtonian laws (nor GR, *nor* classical QM for that matter) allow for such a thing.
At least White realised this, which is why he invented the "pushing against the virtual plasma" as an 'explanation'. Only problem is, there is no such virtual plasma, at least not in any known theoretical framework (or even an unknown but consistent one), and I didn't see White put one forward neither. So, basically, it has the same validity as saying 'it's pushing against dragon-magic'. It explains *nothing* at all, and thus can't be considered a valid explanation for the force measured neither.
Basically, for all intents and purposes, it IS a reaction-less drive, because it adheres to all the hallmarks of one. Claiming it is not doesn't change that fact. It would be akin to someone claiming the apple he throws and comes down is not due to gravity, but due to dragon-magic. Now, one might *CLAIM* it' not due to gravity, but it doesn't change the fact it IS still due to gravity. And until one comes up with proof or at least a consistent theory which is better than the explanation of gravity (aka, a falsifiable explanation of dragon-magic) such claims change nothing and are nonsensical statements.
To the defence of Tajmar, White, and maybe even the inventor: I don't think it are *deliberate* falsehoods. Contrary to say, Rossi with his scam of the E-cats. I don't think they are scamming or consciously deluding people. I've seen the presentation of White, and noted the critical stance of Tajmar: they don't seem to be deliberately confusing people into believing this story. Certainly not the latter. White might have been a bit too speculative, and the scoop-searching press and EM-fanfappers do the rest.
That said, one can rationally argue, or at least ask the question: with a limited budget for scientific research, if it's warranted to put taxpayers' money in such an extremely unlikely claim - without any theory nor decent experimental data to back it up. Even if it's only 500K, it could be better spend on some other scientific projects.
Or, alternatively, the fanfappers could make a kickstarter for it. I've asked this 6 times already, but: where *is* that kickstarter? What's keeping them from doing one? If everyone of the EM-believers would put their money where their mouth is, it would already have gotten 500K. Everyone happy.
I love new things. Only, I don't *believe* every new thing that comes along, until proof of it has been delivered.
And, as usual, you are reversing the burden of proof. And you know it. I have told you numerous, numerous times in the past, so you AR
Nonsense. Name one of the basic natural laws that has been 'broken'.
And no, Newtons' theory of gravity wasn't broken by that of Einstein: http://soi.blogspot.be/2013/05...
I'm saying this in front, because it the typical thing people who are not to knowledgeable about the topic come up with. No, it's not been 'broken'. It is *incorporated* into GR as a special case, but within its domain and a given framework, it remains valid.
Is Skylon the only possible system using atmospheric air?
People seem to be a bit too much focussed on Skylon, although I admit I'm interested in it too, from a technical/technological standpoint.
The *principle* of the matter I just explained stands, though: that which you avoid taking with you as weight (the oxidiser) means you do not have to carry that weight, plus, you don't need to carry the weight of the fuel needed to carry the weight of the oxidiser, plus you do not need the weight of the fuel to lift the weight of the fuel that is needed to lift of the oxidiser, etc. There is a considerable reduction in weight, thus, and - as said - that matters for the useful payload, not for the reduction of *cost of the fuel* as some posts imply.
Whether or not the reduction of weight is always offset by the additional complexity and added weight (of the wings and engines, for instance), remains to be seen, but I would wager that totally depends on what system you use. Especially with non-SSTO systems (the Falcon is non SSTO too, after all) there are myriads of options one could use, and I doubt they'll all be 'worse' than the current Falcon-oxidiser-carying-system in regard of dry mass.
That said, if you're talking economically, and especially if you're talking specifically of Skylon, I think the reusable Falcon is far more viable. But just like all his competitors thought re-usability of a rocket was not (cost/benefit) worthwhile, and Elon Musk is (going to) proving them wrong, it might be that someone smart comes along, also with new ideas how to tackle things, and get affordable air-using systems going, which would be a new 'disruptive technology'. After all, the advantages - at least in principle - I explained in my former post remain valid and are physical sound. It's just a matter of finding a good approach that outpaces current systems.
That said, the point of a SSTO with airbreathing is not the *cost* of the fuel, but the weight-reduction itself, since the added weight that has been avoided in this way can be used for payload.
Even Elon Musk said it's not about the cost of the fuel, but the fact it impacts the useful weight of the payload. ;-)
It's possible, thus, that for LEO an airbreathing spaceplane is more suited than a rocket, especially if that rocket isn't fully SSTO. You say it doesn't save 'much', but the oxidiser on a typical rocket makes out about a third of the total mass... I would call that pretty much.
Does not lay within it's technical capabilities and prowess, but with it's management skills and ability to create a community.
For years I've been a fan of ReactOS, actively participating and contributing to the community, albeit not in the form of a coder. Which, in the (still) current ReactOS mentality, is the only thing that counts for the brass, apparently. Testing ReactOS on a dedicated real-life machine (thus, not in VM), debugging, translating, making info-pages on their wikipedia: nothing really matters to the 'elite' of ReactOS. They just consider you some sort of fodder, and the moment you ask for a bit more transparency (on their financial side, for instance), or try to address the complete lack of community involvement, they bork (and bark) at you - and worse. Time and again I've tried to explain this in the past, that a successful project is NOT merely depended on the technical/coder side of things, but also how you establish a community, and try to involve people in your project. There were some half-baked trials at it, but those were mere lipservice, where it was always a consideration of a top-down approach, not a bottom-up way of seeing things.
Ergo; in the 20 years of their project, they have not succeeded in gathering 1/100th of the community that other projects like Linux have. Again and again I've pointed this out to them, but to no avail. They just refuse to see it, and only want things done strictly to their wishes, with their attitude of finding no other (real) importance to the project than 'code'. Which, granted, is an important part, but which will NOT get you a lively, engaging, and growing community - which is an absolute necessity for any open source project to know success. Eventually, since I kept hitting that nail, they got annoyed (not: they realised the error of their ways) and kicked me out too, the so many-th person who was a tester/sponsor/translator/helper of ReactOS they managed to drive away.
Whatever; so I went away, which is what they wanted. But what did it help them, then? Nothing at all. They view constructive criticism as a threat, not as an opportunity to better themselves and the project. They don't value anything someone does outside of their little constraints, and outside their preconceived notions as to what they see as important, yet have the mouth full of 'community-involvement'. Whatever you do, how many years you may have sponsored or helped out as a non-coder, you just are not counted as having done anything worthwhile. They have no inkling of an idea how to get a thriving community where you allow the bottom-up approach as well.
It's a sad thing to say, but the whole thing is run by people with overblown ego's, trying to protect their little turf and egotistical whims, ignoring anyone else, and being autistically elitist in wanting to decide virtually everything to the minute detail. Its only a community-project in name, but not in essence. And that's why, even after 20 years of operation, their project is just a small-scale project who - in comparison with other projects - has almost nothing to show for. They make some small technical progress year after year, that's true, but they fail to realise how much their ego-driven top-down approach has muffled the project to achieve the grandeur and support it could have had, had the top been more prone to some input from the people actually supporting it.
I've poured hundreds of dollars in it, and spend years on it helping them in my own way, only to kicked out when I pointed out their mistakes and lack of transparency. I still lie, the project, but I can not, in good conscience, support (most of) the people running that program/project. they've done it with me, as they've done it with dozens of people: it's no surprise, thus, that they're still at the small scale they are, without any community to speak off. They can't get any traction, because they kill off everything that would get them traction. There are some good coders under them, to be sure, but almost all of them lack the ma