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User: boristhespider

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  1. Re:Maybe on Most Sensitive Detector Yet Fails To Find Any Signs of Dark Matter · · Score: 2

    I'd be interested in seeing the study you're talking about - the general relativistic models of galaxy rotation that I've seen have been pretty unconvincing, and at most provide around a quarter of the effect.

    What is impressive - and is very definitely phenomenology and not fundamental physics - is the success of MOND. It's been startlingly successful at predicting rotation curves from the observed distribution of luminous matter -- far more so than a standard cold dark matter paradigm -- and it does so with a single universal parameter, unlike the plethora of tunings necessary if one adds in a dark matter halo to the observed standard model matter. The sheer success of MOND, on galactic scales, tells us that something is going on here. Unfortunately what we know isn't going on is that gravity is changed precisely the way MOND changes it. It's ugly, it's ad-hoc and, worse, it doesn't work at all for cluster scales, and can't even be applied on cosmological scales. Still, it's a hell of a lot better at fitting galactic scales than the standard CDM paradigm.

    There was a paper came out the other day that claims to show MONDian effects by tightly tying the CDM into the observed matter. I've not had time to read through it yet but I'm unconvinced since in a CDM model the rotation curve of a spiral galaxy is flat due to a spherical halo of CDM... but the observed matter is resolutely confined to a narrow disc. But that might just be a badly-written abstract.

  2. Re:Maybe on Most Sensitive Detector Yet Fails To Find Any Signs of Dark Matter · · Score: 5, Informative

    "What we have is a phenomenon that is not explained by the calculated mass of the universe."

    Vague statement. What we have are two phenomena, one which is not explained by the observed mass in galaxies or in clusters, and one not explained by the present (and currently only serious) model of the universe. Feel free to propose alternative models for the universe... but make sure that they fit the current observations *at least* as well as that model and fails to break the Solar System. That is hard to do.

    "As a filler we have titled it "Dark Matter" and "Dark Energy" and given it a mathematical correction to the calculations."

    True, with the correction above.

    "The mass issue is fixed if we realize that the size of the universe is larger than the visible horizon."

    No it isn't. That will do precisely nothing for the rotation curves of galaxies and will also basically do nothing for the cosmological problem either. Vague hand-waving and appeals to Mach's principle don't hold without a concrete model. Provide that model and people may be convinced, but at the minute what you're suggesting is startlingly acausal and, as a result, unacceptable.

    "Meaning it is bigger than we can see."

    Very true. No-one thinks that the entire universe is the observed universe.

    "With that we can assume that we can only see 13% of the whole universe and that the reset of it is too far away to see. Now, run those numbers through the formula to calculate the expansion rate of the universe and you get some great results!"

    Nope, you get precisely the same results that we currently get, because while it may startle you, that's what we currently do -- effectively. Thanks to causality, matter outside of our horizon cannot have an effect on us. Basically, something which is far enough away from us that light cannot have made the distance cannot possibly have influenced us. That, or you have to propose a new theory of gravity -- good luck with that one. It's a common game in cosmology, and one which precious few people since Einstein have had any luck at.

    "The energy issue disappears when you realize that the closer an object is to a gravity well the slower time moves."

    No it doesn't. Do you think that we're using non-relativistic models of cosmology? Relativity is at the heart of your statement that gravity wells dilate time, and relativity is at the heart of cosmological models.

    "Thus there is a large time differential between the edge of a given galaxy and intergalactic space. This time differential accounts for the perceived added gravity."

    Now this is a much more interesting statement. Dig out Wiltshire's attempts to use time dilations between galactic clusters and voids to explain the dark energy problem, firmly in the context of general relativity. The fundamentals are not well-studied, but it is promising. However, it goes the opposite direction from your surmise -- it tends towards providing a dark energy rather than a dark matter. It does drive home the point though that it is vital to actually try and calculate something based on an idea, properly rooted in a concrete theory. The answers might be rather different from what you expected...

  3. Re:Clarke on Is Europa Too Prickly To Land On? · · Score: 1

    Now, everything you say is perfectly reasonable (except that the "-1, too obvious" doesn't count for me since I haven't read whatever stupid story they're all referencing anyway. Still off-topic though, though "Redundant" is unfair.).

  4. Re:Clarke on Is Europa Too Prickly To Land On? · · Score: 1

    And for the sake of a single minute he gets modded to +5 Funny and you get down to 0 Redundant.

    No-one ever said the Slashdot moderation system was just.

  5. Re:Obligatory on Is Europa Too Prickly To Land On? · · Score: 1

    And unfortunately you posted AC so no-one with mod points is likely to see this and realise they unfairly modded this guy down and the other one up.

  6. Re:Hydrogen is indeed quite dangerous... on Tesla CEO Elon Musk: Fuel Cells Are 'So Bull@%!#' · · Score: 1

    That's cool, thanks

  7. Re:Hydrogen is indeed quite dangerous... on Tesla CEO Elon Musk: Fuel Cells Are 'So Bull@%!#' · · Score: 1

    Are you suggesting it's *not* stored in a pressurised tank? You'd travel about three foot on that amount of hydrogen.

  8. Re:Mavericks is free? Hmmm... on Apple Announces iPad Air · · Score: 1

    Never intended to make anyone cringe :) And I've never complained to a developer that the app doesn't run on Snow Leopard - it's my choice to do so, so it wouldn't really be fair to bitch that they're not wasting two months of their lives trying to implement a workaround for those lacking the new APIs. I suspect we'll see the free release of Mavericks does help kick people like me who are still on SL into a new system. In all honesty, while the price (or lack of it) obviously helps the timing is serendipitous -- the other day I started looking at upgrading to Mountain Lion so I can get updated or new apps that Snow Leopard doesn't support... and then Mavericks was released.

    I've actually toyed with the idea of backing up my home directory and then installing a fresh copy of Snow Leopard and then a fresh install of Mavericks, if I'm honest. It takes a while to reinstall stuff -- particularly via Macports -- but I *would* have a totally clean installation. Probably a leftover of my days of swapping Windows 3.1 for 3.11 for 95 for 3.11 for 95 for 98 for 95 for 98SE for 2000 for 98SE (and rinse and repeat on those ones - I kept getting frustrated with 98SE's old-fashioned ways, and then frustrated that 2000 was too slow on my machine and, more importantly, couldn't play Thief...)

  9. Re:Mavericks is free? Hmmm... on Apple Announces iPad Air · · Score: 1

    Actually no, I never went in for Time Machine.

  10. Re:Mavericks is free? Hmmm... on Apple Announces iPad Air · · Score: 2

    I've been staying on SL deliberately since Lion came along and broke my Rosetta. Now I don't have anything needing Rosetta but I am increasingly finding that new programs I want only work on Lion and above. So I'm going to upgrade to Mavericks in a few weeks when the first major bug release comes along and means we'll avoid bricking our machines. I'm spending the evening backing up my home directory, and my SL DVD is sitting nearby so I can get straight back to where I am if it all goes horribly wrong.

  11. Re:Why is iPad so much better than iPhone? on Apple Announces iPad Air · · Score: 1

    And now every MP3 player out there can hold 120 gigabytes of music! Oh, no, they can't :( Not trolling, I'd just like an alternative to my aging iPod Classic when it gives up the ghost, but I won't have one - if Apple still sell them, it'll have to be another Classic. Which is a shame, since while I love the Classic I'm no fan at all of iTunes, particularly managing an iPod through it, which always seems too much hassle when all I want to do is drag and drop my music onto the player...

  12. Re:Easy one... on Why Does Windows Have Terrible Battery Life? · · Score: 2, Insightful

    "Slashdot is a fairly technical audience"

    You must be new here.

  13. Re:There's more than one way to do it: FIXED! on How To Develop Unmaintainable Software · · Score: 1

    I love Perl. The only language where I have no idea what I've just written but I do know that somehow it worked and I don't want to mess with it. I know I'm just shit at Perl but even so.

  14. Re:Louis XVI wasn't the last French King on Bloody Rag May Not Have Touched Louis XVI's Severed Head · · Score: 1

    I can't claim any great expertise myself, I studied it for two years at A level - 1785 to 1794 in depth for a year, then 1795-1871 in a bit less depth, so it covered all this period. But it was a longer time back than I like to remember. I might track down some histories.

    As I recall, there were revolutions in 1789, 1791, 1792, 1794 (for a given value of "revolution"; those were at least major constitutional changes), seizure of power by Napoleon in a year I forget around 1800, restoration in 1815 and 1816, then a revolution again in 1831, and another in 1848 which brought Louis-Napoleon to power, though it was another decade before he claimed the title of Emperor. I *think* Les Miserables is set in the '31, which put Louis-Philippe on the throne; it certainly isn't the '89 and I don't think it was the '48. The '48 revolution was widely mirrored across Europe. I think there weren't many more until 1871 when Napoleon III was humiliated by the nascent German Empire (captured along with his army), Paris was stormed, and a revolution followed on.

    I think it was then fairly placid until after the First World War.

    I may have dates a bit wrong, but the major ones, ~1790, ~1830, ~1850, ~1870. All we're missing is an 1810.

  15. Re:Louis XVI wasn't the last French King on Bloody Rag May Not Have Touched Louis XVI's Severed Head · · Score: 1

    That's clearer than saying he was the last of the "dynastic ones" given that the next king of France was his younger brother, and the one following was the youngest of the three. (If you're interested, Louis XVII never reigned and died a few years after his father, but he's counted in the same way that France was ruled both by a Napoleon and his nephew, Napleon III, but never by Napoleon II.) The following king was also descended from Louis XIV, albeit distantly.

    What I'd probably revise your statement to is that Louis XVI was the last autocratic monarch in France, ruling without a constitution limiting or justifying his powers in some way. Napoleon was autocratic, but no monarch, etc. etc., and spoke revolutionary language, etc. etc. (The distinction between the last kings of the ancien regime and the government of Napoleon and, when he claimed the throne, Louis-Napoleon, is one that could be debated for the rest of time, as with that old question "Was Stalin 'The Red Czar'?")

  16. Re:Obvious solution. on Bloody Rag May Not Have Touched Louis XVI's Severed Head · · Score: 1

    It's been alleged in the case of Elizabeth I, where the young girl is meant to have died and been replaced by a boy who didn't even resemble her. This is used to explain why the young Elizabeth was a mild-mannered high achiever, whereas the teenaged and older Elizabeth was a vindictive woman with no great evidence of scholarship, and to explain why she went to such lengths not to marry, and why she looks so odd in her portraits.

    Of course, there are more straightforward explanations, such as being imprisoned by her older sister, taking a throne that was at constant risk of being usurped by a Spanish monarch significantly more powerful than her, living in a court full of intrigues, not marrying because there was no match that didn't come with too many strings attached, or else that staying single opened more opportunities for alliances with monarchs with marriable princes, and looking odd because she may well have been inbred, had been quite sick at quite a few times, and our portraits date (self evidently) from the Tudor age where exact likenesses were not that common.

    But those explanations are really boring compared to the idea that some low-born boy became one of the most famous queens of all time.

  17. Re:Dissident Speech on Do Comments On Web Pages Ruin Science? · · Score: 1

    Very true, all theories in physics are valid within their domain. Special relativity reduces to Newtonian mechanics for velocities significantly less than that of light. General relativity reduces to Newtonian gravity for sufficiently light masses, low accelerations and low speeds. In most situations while it can be entertaining to use the general relativistic description it's also pretty pointless, given that it's orders of magnitude harder than the Newtonian description and the corrections are frequently unobservable. For instance, most of the time NASA will use Newtonian physics to plan the flight path of satellites, because the corrections from GR are utterly insignificant except possibly towards Mercury and further in (and even there the corrections are so small as to be most likely negligible).

    As with Newtonian physics, so with relativity -- there's no doubt they're not a complete theory but will be found to emerge from some more "fundamental" theory in some limit or other, in the same way as Newtonian physics emerges from relativity. (Aspects of Newtonian physics also emerge from quantum mechanics, interestingly. You can cast the Schroedinger equation as two separate equations modelling fluid flow - the Bernoulli equation (basically the evolution of the momentum) and the continuity equation (continuity of mass), with one difference: the Bernoulli equation picks up a complicated correction to the potential energy. Drop that and suddenly you've got nothing more than rotationless fluid mechanics.)

  18. Re:Dissident Speech on Do Comments On Web Pages Ruin Science? · · Score: 4, Interesting

    That's almost exactly the reply I'd like to have made, except that I don't think a lot of these people are acting just to disrupt. They normally seem to passionately believe that they're correct, and their purpose is to convince you - not to enter into a debate. A friend of mine once took up one of these people who had challenged physicists to find a flaw in his "disproof of relativity" (special, of course, since you don't need much beyond high school maths to follow it), and was offering a million pounds to be disproven. So my friend - a professor in cosmology - took him up on it and a couple of months later said "This is pointless; you spend two pages explaining why a particular statement of his is wrong and he replies 'No, you're wrong.' " It would be impossible to win that man's million pounds (a promise allegedly witnessed by a solicitor with funds that can be checked with his accountant), because it's impossible to convince him that he doesn't understand high school maths.

    Absolutely pointless getting into the discussion, since certainly the net result is that you'll have been disrupted.

  19. Re:Use Slashcode. FFS. on Do Comments On Web Pages Ruin Science? · · Score: 1

    In which case I'm not quite sure why you mention the scientists in the sentence at all - which does read as if you're casting aspersions on their professional abilities. If that wasn't your intent then that's fine, but it's what it seems to say...

  20. Re:Use Slashcode. FFS. on Do Comments On Web Pages Ruin Science? · · Score: 2

    "If a collection of scientists and on-line media professionals can't figure out how to put together a working comment section on a website, then I can only wonder at their ability to perform the rest of their duties with any integrity."

    Yes, because a professor in loop quantum gravity is an expert in building comment sections and designing and implementing a robust and working moderation system.

    Jesus Christ.

  21. Re:Dissident Speech on Do Comments On Web Pages Ruin Science? · · Score: 2

    Particularly as in many cases - and I do it myself, shamefully - people are normally very good at skipping the article to read the comments. Of course, Slashdot would never succumb to that kind of thing.

  22. Re:Dissident Speech on Do Comments On Web Pages Ruin Science? · · Score: 4, Interesting

    What also gets very irritating is someone whose last maths was when they were 15 sitting there, at 46, shouting repeatedly on a website that they have disproved Einstein (not really stating what that means; I normally assume they mean disproving E=mc^2), and then refusing to listen to any response. What is *also* irritating are well-intentioned people who equally are 31 years from their last maths lesson trying to quell that line of thought with something that is simply wrong (and frequently, alas, condescendingly wrong) and then the two sides get in a flame war, and we end up feeling we'd have been better off skipping a comment section entirely.

    People with no education in maths or physics claiming without support that Einstein was "wrong" (a word which takes careful definition; no professional physicist would deny, in well-defined boundaries, that predictions of Einstein's theories are incorrect, but that doesn't mean they're "wrong" in the way that is often bandied around) are surprisingly common. About six years back I started compiling a database of emails that I was sent and books my department was sent that argued Einstein was wrong in manifold, creative, naive, inaccurate -- and yet frequently different -- ways. After a few months I got bored of it because they began repeating themselves and the volume was huge.

    This was before comments threads. If I'd done it when comments threads were set up I may never have gained my PhD thanks to time spent arguing with people online who refused to learn anything about the topic they were stubbornly opposing - even topics the details of which they stated were inaccurate. Of course, me not getting my PhD probably wouldn't have been much of a loss to science, but I've enjoyed venting anyway.

  23. Re:Uh... on Somebody Stole 7 Milliseconds From the Federal Reserve · · Score: 1

    Yeah but learning that involves reading the article.

    (Also, thanks, it does provide one entirely sane and legal explanation.)

  24. Re:Uh... on Somebody Stole 7 Milliseconds From the Federal Reserve · · Score: 1

    Manipulating the past is a pricey game. Perhaps this is actually the Higgs recovering its losses from the other year.

  25. Re:Uh... on Somebody Stole 7 Milliseconds From the Federal Reserve · · Score: 1

    Haha that assumed I intended Washington, Tyne and Wear - which doesn't loom very large in the British pysche - and gave me a value of 20ms.