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Light Pressure & Gravity

  1. May 21, 2015 #1
    Playing a game that did it's best to emulate the milky way. Anyways it certainly gets across just how much light, perhaps better and more accurately how much radiation there would be near the centre of our galaxy.

    Recently read about "light pressure", giving an example of 30 billion laser pointers being capable of lifting maybe a penny or so.

    That's not a great ratio, but I imagine in the extreme case of the centre of a "normal" galaxy the effect would add an additional "metric" to calculating motion / kinematics of a galaxy.

    So i guess the radiation in summation would be centrifugal, perhaps "working" against the summed gravitational attraction of less massive objects toward the centre, among many other things im sure.

    Does light pressure have a measurable effect on galaxies? If so simply put what are they? And is there a better term than "light" pressure. light seems limiting in wavelength lol

    (I believe there was a man made satellite that had a velocity correction because of the suns "light" pressure)

    edit: lol i see a well done wiki page on "radiation pressure", mods feel free to delete
    Last edited: May 21, 2015
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  3. May 22, 2015 #2

    Simon Bridge

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    Which game? Please cite anything you refer to so we know what you are talking about.

    Where did you read this?

    I don't think we'd usually want to factor in the extra effect as a kind of geometry but I suppose it could be done.

    Light does not only travel radially - but light pressure is an important effect opposing the gravitation of very bright objects like stars.

    Yes - though the topic is too big. You can google for papers in astrophysics. You could start with...
    ... there you go. I don't know about "well done" - but wikipedia can be a useful place to start.

    To get mods to delete a post or a thread, just hit the report button below is... it's OK to report yourself.
    For next time, please remember to cite anything you want to refer to. If the questions arises from something you have read - for eg. - then be specific: what did you read? If you are too embarrassed to mention the source, then it is probably wrong... find another source.

    But well done for finding the info you needed on your own :)

  4. May 23, 2015 #3
    Ahaha, note my qualitative remark of "well done" is compared to what I knew before hand. That wiki page is "well done" compared to knowing nothing lol.

    The game is called Elite dangerous!! Come and play in the milky way! :smile: Just seeing how voluminous a star 50 times more so than ours is, it takes about 100 light seconds (distance) to get a full view of such a large object, is "fun".

    Excerpt from Here: This time, he [David Braben] used astronomy rather than the Fibonacci sequence to arrange his galaxy. “I wanted to make the galaxy as accurate as possible so that the results of that exploration would make sense to people,” Braben said. “In the game, every single star in the real night sky is present, some hundred and fifty thousand of them, and you can visit each one. Even the clouds of stars that make up the Milky Way are included: some four hundred billion stars, their planetary systems, and moons are present, all waiting to be explored.”

    One more plug for the game from the same article: "Floor van Leeuwen helps run the Gaia satellite project, which aims to chart a three-dimensional map of the Milky Way, at the Cambridge Institute of Astronomy. According to van Leeuwen, models of space such as those seen in Elite: Dangerous are crucial to expanding our understanding of the universe."

    ahahaha I don't know about that, but it is a fun game. And the milky way now seems bigger to me than it ever did...it's almost stupid how vast distances in space are, specifically when compared to the max speed within it. The whole "thing plays out" (universe) slower than molasses, but suppose that's good!! lol

    Okay for the laser pointer thing, not sure where I first read it but managed to dig it up again. It is used as a reference in this thesis on light & sound. The bibliography has the coordinates as "H. X. Tang, “May the force of light be with you,” IEEE Spectrum, vol. 46, no. 10,pp. 46–51, 2009" It's behind a paywall.

    I had metric in quotes to try and distinguish it from the usual physics use, meant metric as just another parameter, variable, physical effect to consider in computing whatever.​
    Last edited: May 23, 2015
  5. May 23, 2015 #4

    Simon Bridge

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    Good work.
    When you include the references, you'll find that what you write actually reads better and people answering questions are going to be more confident that they understand you. You'll get good/useful answers faster that way.
    You'll also get to share discoveries - like not everyone here will know of that game :)
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