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    Default Dark Matter - don't we see all we need? Part 1.



    The HUDF image spanned 11 square arc-minutes, and contained ten thousand galaxies. Thus, the whole sky (=150 million square arc-minutes) likely contains ~140 billion galaxies.

    Now, the Critical Density, for our cosmos (H = 75 km/s/Mpc), is ~175 billion solar masses per cubic Mpc. And, again assuming that our universe is matter dominated, and critical, the actual "horizon distance", out to the edge of our visible universe, accounting for the stretching away of spacetime from earth, is 3ct = 8000 Mpc (Carroll & Ostlie. Intro. Mod. Astrophys., p.1261). And, that corresponds to a volume of (4pi/3)*R^3 = 2100 Gpc^3. Thus, there "should" be 175 billion solar masses/Mpc3 x 2100 billion Mpc3 = 375,000 billion billion solar masses in our Hubble Volume. To account for that, we must associate ~2.7 trillion solar masses per observed galaxy. And, our Milky Way alone accounts for 0.7 trillion solar masses, all w/in 0.08 Mpc of the galactic core. That's within a factor of 4. Indeed, astronomers already estimate, that there is 4x more extra-galactic IGM material, than galactic matter.

    Moreover, the HUDF did not capture all the nascent galaxies, beginning to be born, since its exposure time was too short, to see out deeper than redshift = 7. It does not seem preposterous to presume, that "we (almost) already looking at" all of the baryons we need, to account for critical density, especially with all the reports of galaxies & stars forming as early as z = 12+. Indeed, the current actual comoving distance, out to some redshift z, is d(z) = 3ct (1 - 1/(1+z)^3/2). For z = 7, that means the HUDF only saw out 96% of the way to the 'edge' of the currently-Visible-Universe. Taking the cube, that means the HUDF overlooks 14% of our cVU. So, we can confidently expect there to be 150 billion galaxies in our cVU, meaning we need associate only 2.3 trillion solar-masses per galaxy, to account for critical density.

    By way of comparison, the HDF contains 3000 galaxies, in 5.7 square arc-minutes, out to z = 4. That translates into 1 part in 26 million of the sky imaged; and, only 91% of the way out to the 'edge' of the cVU, or only 75% of the volume. Thus, the HDF would predict there to be 100 billion galaxies in our cVU. That's comparable to the HUDF, but 50% less, which seems somewhat significant -- there are many ultra-dim objects, that only show up, on ultra-long exposures. (If, at 75% volume coverage, we count 100e9 galaxies; and, at 86% volume coverage, 150e9 galaxies; then, a hypothetical 'HUUUDF', w/ ~100% volume coverage, could count 200-250e9 galaxies -- as little as 1.5 trillion solar-masses per galaxy. We live in a low-surface-brightness, dim, cosmos. Most of the mass is 'humble', and doesn't boast about itself, advertising across the cosmos.)

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    .
    Just to add to your post...

    I agree, I think this is more along the right track. The idea of "dark matter" is an incomplete hypothesis at best, and an excuse at the worst.

    Take a look at the Hubble Deep field image... This image was taken at a known location in the sky where there are no nebulae, stars or other objects to clutter the image. The "keyhole" shot would be equivalent to looking through and aperture the size of a dime from 70 feet away.. Just check out this photo of what they saw under these circumstances- seemingly never ending visible matter:


    .This is just an amazing image, and I think explains a lot.
    Attached Images Attached Images

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    Quote Originally Posted by Space Jockey View Post
    .
    Just to add to your post...

    I agree, I think this is more along the right track. The idea of "dark matter" is an incomplete hypothesis at best, and an excuse at the worst.

    Take a look at the Hubble Deep field image... This image was taken at a known location in the sky where there are no nebulae, stars or other objects to clutter the image. The "keyhole" shot would be equivalent to looking through and aperture the size of a dime from 70 feet away.. Just check out this photo of what they saw under these circumstances- seemingly never ending visible matter:


    .This is just an amazing image, and I think explains a lot.
    hi SJ.
    would you please elaborate on what it explains??
    I am trying to understand a lot of things. and reading as much as I can. but I have a long way to go.
    any elaborations about your comment would be greatly appreciated.

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    .



    Hi Chas, I think what this post demonstrates is the idea of dark matter on both a galactic and universal scale is based on our limited perception of what we as humans can sense through our technology..be it optical or radio methods. The point I was making in this one tiny "keyhole" image into deep space, the HST captured much more visible matter than they ever dreamed possible.

    I personally do not believe there is an invisible "dark matter" out there.. I think it is a miscalculation based on incomplete observation,.

    It would be impossible for even millions of HST's to survey they entire universe in this manner, because the Field of view is basically like looking through a strand of fiber-optic cable.. make sense now?



    .

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    thank you SJ.
    I am trying to make sense of this.
    do you mean that you think that there is a huge amount of matter in the universe that is visible???
    we just can't see it all because we don't have the technology to observe the universe because its so big??
    if we could position enough telescopes to look in every direction with a field the size of a fiber optic strand, then we would observe all the matter in the observable universe. (this would mean having an estimate of a trillion trillion trillion........... telescopes).
    so this idea of an invisible dark matter is just plain wrong.

    how am I doing???
    Last edited by chas53; 05-30-2011 at 08:19 PM.

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    Quote Originally Posted by Space Jockey View Post
    .
    Just to add to your post...

    I agree, I think this is more along the right track. The idea of "dark matter" is an incomplete hypothesis at best, and an excuse at the worst.

    Take a look at the Hubble Deep field image... This image was taken at a known location in the sky where there are no nebulae, stars or other objects to clutter the image. The "keyhole" shot would be equivalent to looking through and aperture the size of a dime from 70 feet away.. Just check out this photo of what they saw under these circumstances- seemingly never ending visible matter:


    .This is just an amazing image, and I think explains a lot.

    I'm in total agreement with you.
    Physics as we know it may have to be re written once we move beyond the gravity of our own galaxy into the vast emptiness of space.
    all the laws of physics are based on the forces of gravity as we know it
    We haven't even ventured past our own solar system let alone the galaxy.
    Dark matter and dark energy are fascinating concepts and more suited to our limited understanding ,but a best guess is all it is.
    Ken

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    I think this HST deep field telescope shot is part of the answer.. and I also personally believe there is some kind of unified gravitational effect that is dependent on differential mass and a gravitational "give and take" that can explain this. This is just a hypothesis on my part so take it with a grain of salt

    But as far as some kind of "dark matter".. It is just an imaginary "ADD YOUR VALUE HERE" to the equation to make a model for the cosmos work.

    I can tell you and others here with 100% certainty that at this point of understanding it is not a valid scientific conclusion.
    Last edited by Space Jockey; 05-30-2011 at 09:55 PM.

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    Some of the most true to life facts come from dreamers who dare to test the hypothesis of known science.
    Who knows ... maybe beyond gravitational mass the speed of light doesn't have a set speed limit as we know here.
    that would sure explain the acceleration of distant galaxies.
    Everything we know is more in the visual spectrum and even when we pull light apart in individual wave lengths it has been effected by gravity.
    Then again I hated math because of the unknown variables applied to solve a made up problem that was easier for me to solve by trial and error.
    So its down to just an opinion on my part.
    Ken

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    Quote Originally Posted by Space Jockey View Post
    I can tell you and others here with 100% certainty that at this point of understanding it is not a valid scientific conclusion.
    You are absolutely correct about that.

    However, you have to remember that it was never intended to be a conclusion in the first place. "Dark matter" is, and always was intended to be, merely a name for an unknown. For some reason, naming an unknown in this case seems to offend people, but it is hard to talk about it without giving it a name.

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    Quote Originally Posted by kwalker View Post
    Then again I hated math because of the unknown variables applied to solve a made up problem that was easier for me to solve by trial and error.
    No old Men (excepting Dr. Wallis) love Mathematics.
    — Sir Isaac Newton

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