The Story of the Universe: : Tutorial :

Discussion in 'Astronomy, Exobiology, & Cosmology' started by paddoboy, Oct 10, 2015.

  1. paddoboy Valued Senior Member

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    There is no paradox. It's simply a question of the DM present within the solar system, being drowned out by larger effects of the galactic gravitational interactions.
    The Universe is expanding over large scales...Yet our local group is gravitationally bound. What's happening is that the large scale universal expansion is overcome by smaller scale gravitational interactions such as our local group.
     
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  3. paddoboy Valued Senior Member

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    No logic and sensibility as generally shown via the scientific method and peer review.
     
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  5. river Valued Senior Member

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    Really

    And this is logical to you pad?
     
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  7. The God Valued Senior Member

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    Total ignorant mix up...
     
  8. paddoboy Valued Senior Member

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  9. Futilitist This so called forum is a fraud... Registered Senior Member

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    He has confused dark energy with dark matter.

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    He is still thinking about raisin bread!

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    Yes there damn well is. If dark matter exists, it should logically affect the orbital motions of planets around the sun. But, according to observation, it does not. That is a genuine paradox. Wake up.

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    Can you offer an explanation for the dark matter paradox?



    ---Futilitist

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  10. paddoboy Valued Senior Member

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    Only from your side.

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    http://cdms.berkeley.edu/Education/DMpages/FAQ/question36.html

    Q Do we measure any gravitational effect of dark matter in our solar system? Are the orbits of our planets influenced by dark matter? If there are no gravitational effects of dark matter in the solar system, why do we observe them in the galaxies? Is dark matter not uniformly distributed into space?

    A These are excellent questions! Here are my answers (somewhat out of order):

    DARK MATTER IN THE SOLAR SYSTEM
    Dark matter should have gravitational effects on the planets orbits and on space probes, but we are so far unable to detect them. This is not surprising, however, because they are hidden by bigger effects: the gravitational pulls of the sun and planets are much, much larger.

    The average density of dark matter near the solar system is approximately 1 proton-mass for every 3 cubic centimeters, which is roughly 6x10-28 kg/cm3. The actual density might be a little lower or higher, but this is the right order of magnitude.

    Based on this number, we can work out the total mass of dark matter within the radius of Earth's orbit around the sun: for an orbital radius of 100 million km, we get a total of 2.3x1012 kg of dark matter within the Earth's orbit. This sounds like a lot, but the sun's mass is 2x1030 kg. All of that dark matter only weighs 10-18 as much as the sun does, so we cannot detect the tiny pull of dark matter upon the Earth's orbit. The same story is true all over the solar system: the gravitational pulls of the sun and planets are always much larger than that of the dark matter.

    DARK MATTER IN A GALAXY
    Now consider the effect of dark matter upon the orbit of the sun around the galactic center. Let's suppose that the density of the dark matter is the same everywhere in the galaxy; this is NOT true (the density is much higher near the galactic center), so the dark matter mass will really be higher than we calculate.

    The radius of the sun's orbit is about 2.5x1017 km, so the total mass of dark matter within that orbit is 6x1040 kg. This is the mass of 3x1010 (30 billion) stars like the sun! The entire galaxy only contains ~100 billion stars, so the dark matter does have a significant effect on the sun's orbit through the galaxy. For objects farther out near the edge of the galaxy, the dark matter is actually the main thing keeping them in their orbits. This is more or less how dark matter was discovered by astronomer Vera Rubin and others: the orbital speeds of galactic stars and gas clouds don't match our expectations from the visible matter.

    In other words, a galaxy is much lower in density than the solar system, so the small dark matter density becomes much more important.

    DARK MATTER DISTRIBUTION
    Dark matter is not distributed uniformly in space. The galaxy is embedded in a large cloud of dark matter, and gravity makes this cloud denser in the center than at the edges. The density varies slowly over many light years, though some theories suggest that there could be "clumps" on smaller scales than that.
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    http://curious.astro.cornell.edu/th...g-along-with-the-entire-universe-intermediate


    Our nearest galactic neighbors, namely the Local Group, consists mainly of our galaxy, the Andromeda galaxy, the Large and Small Magellanic Clouds as well as about 30 small galaxies within ~1-2 Mpc from us. The two largest galaxies, the Milky Way and the Andromeda, are moving towards each other at about 119 km/s instead of expanding along with the rest of the universe because the gravitational attraction between the two is stronger. In fact, the entire Local Group is collapsing under the gravitational attraction, and in about 3 billion years, the Milky Way and Andromeda will collide! Ahhhh!

    On a larger scale, the Local Group is moving towards the Local Supercluster at about 600 km/s, but it doesn't head straight for the center of the Local Supercluster as expected. Astronomers think that this is because of a large cluster of galaxies beyond the Local Supercluster that we call the "Great Attractor." Though its position and structure isn't known exactly, its existence is inferred from how the Local Group is moving towards the Local Supercluster.

    This is a very fun page about The Structure of the Universe that lets you see different structures, from the nearest neighboring
     
  11. paddoboy Valued Senior Member

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    No there damn well is not. There is no paradox. See previous post.
     
  12. river Valued Senior Member

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    Pad..pad...pad...
    Pad.......Astronomers THINK that this.....
     
  13. The God Valued Senior Member

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    Paddoboy,

    Let me take you to the past (mentally)...around couple of century ago..

    Cosmology/astronomy was in the domain of churches and popes.....guys like Copernicus / Galileo they were declared fools and some of them were prosecuted also for talking science, because many of these popseys were fools, but they were mainstream of that time. And mind you these popseys had many blind stupid supporters like you...But at the end science won. Today's cosmology is driven by a different kind of popseys, Fame, Fund and F..k is the religion for them, these popseys were abandoned by Einstein himself, but they continue to mushroom, and unfortunately as on date there is no dearth of stupid supporters too. But for how long ?

    Disclaimer: always nice guys are there.
     
  14. paddoboy Valued Senior Member

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    riv, riv, riv...Perhaps you should give it a go?....thinking that is.

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  15. paddoboy Valued Senior Member

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    Ladies and Gentleman! A great example of "spitting the dummy" along with "tall poppy syndrome" and of course the over riding fact of this character as was his predecessor rajesh, being like the proverbial cocky on the biscuit tin.
    He/they just aint in it!
     
  16. river Valued Senior Member

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    Pad I thought along this line 30yrs ago.
     
  17. paddoboy Valued Senior Member

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  18. The God Valued Senior Member

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    What is this invoking ? Calling Almighty ? then you do not have to shout like this ? I am there and plan to be online for some more time..
     
  19. river Valued Senior Member

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    Pad ....30yrs ago
     
  20. paddoboy Valued Senior Member

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    So, you believe the accepted scenario has now changed?
    Would you like to offer some reputable link or reference to support that this has changed of late.
    Or are you just performing your usual?
     
  21. paddoboy Valued Senior Member

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    And I'll certainly be around also to refute your nonsensical alternative claims.
    Not that its needed. I mean you are not really impressing anyone and mainstream knowledege and thinking survives without you.
    Again, like that cocky on the biscuit tin: You just aint in it.

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  22. river Valued Senior Member

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    The thing is pad I have but right now in your exploration of Einstein is where you are.
     
  23. paddoboy Valued Senior Member

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    The Ernest. C . Watson Lecture series:
    Caltech:
    Kip. S. Thorne:
    Richard Feynamn:

    WARPED SPACETIME:
    BLACK HOLES:
    GRAVITATIONAL WAVES:
    ACCELERATING UNIVERSE:


     

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