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Space

Why Haven't the Arms of Spiral Galaxies Wound Up After All This Time? (forbes.com) 94

StartsWithABang writes: When you take a look at a spiral galaxy in the night sky, it seems obvious that the stars on the inner parts of the galaxy are going to orbit in less time than the stars in the outer part. This turns out to be true, something we've figured out even though the timescales for galaxies to complete a full revolution are far longer than we've ever been able to observe. But one thing that doesn't happen is that the arms don't "wind up," meaning that the galaxies don't see the spiral patterns intensify as they age. Even though we first observed spiral structure in galaxies back in the mid-1800s, we didn't understand what the cause of this effect was for over 100 years. Yet now, not only do we understand it, but we can explain why galaxies will never wind up over time, and how this effect is true with or without dark matter.
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Why Haven't the Arms of Spiral Galaxies Wound Up After All This Time?

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  • by mlheur ( 212082 ) on Sunday December 13, 2015 @05:06AM (#51108821)
    Wheres TFA?
  • Actual Link (Score:5, Informative)

    by cfalcon ( 779563 ) on Sunday December 13, 2015 @05:08AM (#51108827)

    Actual Link (warning: still Forbes): http://www.forbes.com/sites/st... [forbes.com]

    • by KGIII ( 973947 )

      Wants to take me to the welcome page.

      So, I'm going to presume that the arms haven't wound up yet because they've not yet found another, worthy, galaxy to offer a warm and loving embrace. The galaxy is lonely, it simply is waiting for someone to come give it a hug and tell it that everything will be all better now.

      • by cfalcon ( 779563 )

        Of course it takes you to the "welcome page", I said it was still a Forbes link. Why would I give you that warning otherwise?

        What it does is eventually resolve to the article, which had presumably changed destination urls or something- the original one went to the proper html name, but in an improper directory, hence 404.

        • by KGIII ( 973947 )

          Ah - my script blocking disables that whole thing. Thus it takes me to the welcome page and no further. Forbes is broken for me unless I go through the effort of fixing it, I guess. To be honest, I'm not sure it's worth it. I was quite confused as to why you might be linking it when it was still broken. It turns out, it's broken because I use uMatrix and haven't decided to let them through with their scripts. That seems, well, unlikely to change but now I know why it's happening. Thanks!

          • by cfalcon ( 779563 )

            > Forbes is broken for me unless I go through the effort of fixing it, I guess.

            Correct, it's a shit site. Each url currently (they change the details about monthly) points to some garbagebutt thing like what you found, that conditionally loads the rest of the site. Their current festival of poop works ok with uBlock Origin, but it utterly fails with noscript (even allowing all their hundred random malware domains). I'm at the point where I have three browsers open (currently three different browsers,

            • by KGIII ( 973947 )

              Yeah, I think I'll skip setting up a special configuration in uMatrix (NoScript on steroids, like an old-school software firewall but for your browser specifically) and just have to go the whole route of waiting for others to comment or just making wild-arsed assumptions without reading the article. So, I guess it won't be that much of a change. I could have sworn the site worked for me the last time I clicked on a link in an article. I did notice it was not working in a journal post recently but I figured

    • https://en.wikipedia.org/wiki/... [wikipedia.org] Tim S.

      Actual Link (warning: still Forbes): http://www.forbes.com/sites/st... [forbes.com]

  • by DNS-and-BIND ( 461968 ) on Sunday December 13, 2015 @05:25AM (#51108867) Homepage

    An account repeatedly posting links to the same website, forbes.com. That website is full of ads, which are being shown to the audience that clicks through from Slashdot. The content is scienc-y stuff that would attract an audience's like Slashdot. I don't know what the ad was because the adblocker caught it, all I got was a forbes.com landing page and a famous quotation. Then I clicked to enter the article and was directed to http://www.forbes.com/sites/et... [forbes.com] which is a "4-0-Forbes" error which means 404 not found.

    The fact that this is happening again and again is no coincidence. There is clearly collusion and someone is getting paid. A shockingly low amount, I suspect. Or a favor is being repaid, or other non-monetary gain. But damn there are too many ads going off for it not to be. On the other hand, I don't really know how successful the operation is. You have to question the wisdom of an operation that doesn't even bother disguising the posting account, and then markets to the one audience in the world that is most enthusiastic about ad-blockers.

    • by Anonymous Coward

      The guy posts exactly one Forbes link a day to the column "Starts With A Bang" written by Ethan Siegel who is merely a contributor to The Forbes. You want to know why? Because StartsWithABang IS Ethan Siegel and he is trying to justify his position at The Forber by spamming his CRAPPY articles all over Slashdot. Maybe I should tip the guys at The Forbes about this spamming behaviour, maybe it will make them rethink this guy's merits.

      • Maybe I should tip the guys at The Forbes about this spamming behaviour, maybe it will make them rethink this guy's merits.

        Forbes is circling the bowl because they are fucking clueless buffoons who do not understand modern media and who are experiencing cognitive dissonance over the fact. If you managed to bring this to their attention, they would simply be happy that they are receiving free advertising.

      • Following "Starts with a Bang"'s personal page, he only has one comment posted, to fix a type on one of his submissions last year.

        Time to block his posts.

        • Time to block his posts.

          Do you have a technique for doing that? Without scrapping Slashdot totally?

          • I thought there was an option to block posts or submissions from a particular user. Maybe I'm thinking of another forum site, or just remembering something that was removed years ago.

            But scrapping slashdot is always an option.

    • An account repeatedly posting links to the same website, forbes.com. That website is full of ads, which are being shown to the audience that clicks through from Slashdot.

      Happily, I use adblock, noscript, privacy badger, ..., so I don't see the ads. But apart from that, I have learned to recognise the signs - the vaguely scientific stuff, 'on-a-grand-scale' non-news etc. It is always being trumpeted out as 'Finally We Understand ...', and it invariably turns out to be big, glossy pictures, florid language and trivia about well-known phenomena.

      The fact that this is happening again and again is no coincidence. There is clearly collusion and someone is getting paid.

      It is called fabulous things like 'The New Economy', and yes, it is mostly bogus - very close to outright fraud, because it is all abo

    • by gtall ( 79522 )

      Noscript actually puked on my keyboard trying to visit that site. Gotta run for some cleaner...

    • I'm pretty sure Dice/Slashdot isn't getting paid a cent for it, and the editors are just as lazy/incompetent as ever. And Forbes isn't paying, since the same thing happened when startswithabang articles were on medium.com. It's possible that the people who vote up these articles in the firehose are being paid, but it's more likely that they just think it sounds interesting but don't bother to RTFA, like most slashdoters.

    • An account repeatedly posting links to the same website, forbes.com. That website is full of ads, which are being shown to the audience that clicks through from Slashdot. The content is scienc-y stuff that would attract an audience's like Slashdot.

      The fact that this is happening again and again is no coincidence. There is clearly collusion and someone is getting paid. A shockingly low amount, I suspect. You have to question the wisdom of an operation that doesn't even bother disguising the posting account, and then markets to the one audience in the world that is most enthusiastic about ad-blockers.

      At least it's not Bennett.

    • by Anonymous Coward

      The article is garbage, too:

      1) A large segment is devoted to explaining that, as you examine stars further from the centre of a spiral galaxy "the speed remains constant". This statement is accompanied by a graph clearly showing that speed increases with distance, from about 40 km/s to 120 km/s - a factor of three change is hardly "constant" in this context.

      2) The key claim - that spiral arms are standing waves of density - is presented without any justification or explanation of how this could work whatsoe

  • The website that makes you click through an abbey even though it knows the final destination doesn't even exist.

    • Forbes is clinging desperately to relevance and their barbaric business model. The execs over there are getting worried about their bonuses. I didn't make it to the article before I threw up my hands in dismay. Here's a link to an earthsky article on the same subject. http://earthsky.org/space/how-... [earthsky.org]
    • by Tablizer ( 95088 )

      Abbey Road is a Long and Winding Road? Let it be.

  • But can we explain (Score:5, Interesting)

    by thegarbz ( 1787294 ) on Sunday December 13, 2015 @06:10AM (#51108959)

    Why slashdot insists on linking to every single article posted by Startwithabang on the incredibly shitty advert infested Forbes?

  • by MichaelSmith ( 789609 ) on Sunday December 13, 2015 @06:42AM (#51109007) Homepage Journal

    Spiral arms are not solid structures which can wind up. They are zones of star formation created by waves which propagate through the galaxy.

    • There is a simplistic but useful video at http://www.alicesastroinfo.com... [alicesastroinfo.com] that describes the issue. They're effectively high density star regions, much like the funnel of a tornado or of a hurricane will form spirals.

    • Exactly. They're actually RADIAL compression waves I'd imagine, and they DO 'wind up' to a certain extent, but they also don't propagate strictly radially, so the wind up can only go so far.

      However, its not so much that they are 'waves of star formation' as that they are DENSITY waves. Material moving towards an arm speeds up, because the gravity of the denser arm pulls it in more quickly, and material moving OUT of the arm is slowed, so as stuff orbits the galaxy it spends more of its time inside these den

    • by Michael Woodhams ( 112247 ) on Sunday December 13, 2015 @06:17PM (#51111093) Journal

      Furthermore this is not news - it was uncontroversial when I studied astronomy 25 years ago.

      As I'm unwilling to do battle with the Forbes website, I don't know whether TFA has anything new to add to this.

  • And it's taking a very^5*10000E long time to get here.
  • New theories needed (Score:5, Interesting)

    by taylorius ( 221419 ) on Sunday December 13, 2015 @06:58AM (#51109037) Homepage

    Mike McCulloch's MiHsC is a theory that makes some good predictions for things of this sort. It predicts a variety of anomalies quite successfully, without any tunable parameters needing adjustment. Mike McCulloch is a lecturer at Plymouth University in the UK, and he writes about his theory on this site, quite interesting stuff.

    http://physicsfromtheedge.blogspot.co.uk/

  • by Anonymous Coward

    So you have to wait a long while, light years even, to notice.

  • by donkeyb ( 965462 ) on Sunday December 13, 2015 @09:11AM (#51109277)
    Phil Plait's excellent series of PBS shorts explains all this in a better fashion (I think), and he doesn't spam himself all over slashdot, so is more deserving of our time :) Galaxies part 1 is here: https://www.youtube.com/watch?... [youtube.com] Part 2 is linked from there. :)

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