Expanding Matter. And Space, to a lesser degree?

Discussion in 'Fred's House of Pancakes' started by Mendel Leisk, Sep 3, 2019.

  1. Mendel Leisk

    Mendel Leisk Senior Member

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    Was watching an interesting show on gravity over the last few days, actually rewatched it a few times. Some points they made:

    1. A stationary accelerometer will register 9.8 meters per second vertical acceleration (or 1 g).

    2. Drop the accelerometer, say off the edge of a tall building or cliff, and it will register zero acceleration, for the duration of the fall.

    3. Throw a ball out horizontally, and it will gradually curve down, return to earth.

    A decade or two back I toyed with an idea: what if everything is expanding, at a steadily accelerating rate, 9.8 meters per second. The earth is expanding, you're expanding, all the yardsticks. Guess it's a done deal?



    The above link kind of nags you to "log in", I was ok with my Google ID. A quote from the article:

    So, understanding relativity and gravity is mainly a matter of overcoming our resistance to a peculiar, embarrassingly implausible idea: that while you read this, the space that contains our planet — including every molecule in our bodies, everything we can see out to the horizon, and every ruler on its surface — will double in size.

    Link to the Gravity show, watchable 2 parter:

    The Amazing World of Gravity | TVo_Org
     
    #1 Mendel Leisk, Sep 3, 2019
    Last edited: Sep 3, 2019
  2. fuzzy1

    fuzzy1 Senior Member

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    Just don't confuse this with the meaning cosmologists are using for 'expanding universe'. They are talking about something different.
     
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah. Maybe title should be "Expanding Matter", more succinct. Done.
     
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    This page kinda pours cold water on the above:

    Gravity as Expansion and Many Worlds

    Mentions exceptions, super-dense dwarf stars for example.

    Still, it's interesting. If something has all the earmarks of being something, ie gravity being due to an accelerating expansion, even if it's ultimately not the case, maybe it's still worthwhile to consider it, as a model.
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    Porridge for breakfast day, and I like to chop a little apple into it. This time of year I can get them from our weed apple tree.

    So I was out there, giving it a shake, and they're thudding down, one even bopped me on the head lol.

    And it occurred to me, kind of topical?

    IMG_1129.JPG
     
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  6. bisco

    bisco cookie crumbler

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    newton?:p
     
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  7. vvillovv

    vvillovv Active Member

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    The hard part for me is visualizing/understanding - all the densest materials everyone knows of or has touched is mostly space.
    ie: how can iron be mostly space if I can't see any spaces in it?
    gotta love atomic structures (microscopic) as opposed to astrophysical structures (macroscopic)
     
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    One interesting analogy:

    In my engineering drafting career, sometime we needed to calculate ball bin volume. The balls being steel balls of uniform diameter (for ball mill). Funny thing: no matter what the ball diameter, the volume of any given weight was the same. There was always the same ratio of steel to void.

    I looked up the moon's gravity: almost exactly 1/6 of earth's. But: the moon's radius is no where near 1/6 of earth's. More coffin nails I guess.
     
  9. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    If everything is expanding, how do we maintain constant latency on fiber and radio links that span hemispheres? An expansion would mean the endpoints are getting further away, no?
     
    #9 Leadfoot J. McCoalroller, Sep 4, 2019
    Last edited: Sep 4, 2019
  10. iplug

    iplug Senior Member

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    And what of the physics of interatomic forces? There are known constants here that are dependent on interatomic distances. How to we account for that if atoms are accelerating away from each other but the constants do not change?
     
  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Yes and yes.

    Maybe it's just an imperfect model, but everything on earth behaves as if there is a universal, accelerating expansion: the steady-Eddy one G vertical, how a thrown ball curves into a downward trajectory. Or how an accelerometer tossed into the air, or dropped from a height, registers zero G forces, as long as it's airborne.

    So maybe there's something comparable going on?
     
    #11 Mendel Leisk, Sep 4, 2019
    Last edited: Sep 4, 2019
  12. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Wait, is this the new flat earth?
     
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  13. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    That accelerometer is only going to show something as long as there is something there to hold it up.

    Once there is nothing there to hold it up, it will accelerate. Once it has done this, it won’t register any acceleration until it bottoms out. That’s normal.
     
  14. Mendel Leisk

    Mendel Leisk Senior Member

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    That's quite right, but oddly contradictory: when the acclerometer is "stationary", say sitting on a table top, it registers 1G vertical acceleration. And when you drop it down an elevator shaft, all the way down it registers no acceleration, as it accelerates.

    I linked one article, in post #4, which I readily concede shuts down the premise in the thread title. That article is just the tip-of-iceberg, links back to this tome, Reflections On Relativity, by Kevin Brown:

    Reflections on Relativity

    I managed a few paragraphs of the preface. :oops:
     
  15. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    It’s not contradictory. You understand the device can only measure the difference between two parts of itself, right? if it is in free space, both parts of it will be pulled down by the exact same force being exerted on everything else there.

    Gravity is constantly attracting all mass all the time. A small electronic accelerometer can’t immediately tell that it’s already under the influence of gravity, it can just show forces acting against it. Like your tabletop holding it up at 1G.
     
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  16. Mendel Leisk

    Mendel Leisk Senior Member

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    Yes. Still, if the accelerometer were in a spaceship, which commenced accelerating at 1G, it would behave exactly as it does on earth, sitting on that table. Puzzling as heck.
     
  17. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    A 1G acceleration is a 1G acceleration, doesn’t really matter whether you’re paying a fuel bill for it or not.
     
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  18. Mendel Leisk

    Mendel Leisk Senior Member

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    Last year's crop was better, btw. Maybe not enough rain this year. One day's pickings, last year:

    upload_2019-9-5_6-58-24.png
     
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  19. vvillovv

    vvillovv Active Member

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    Very pretty apples above. May I assume? they are as tasty as pretty? If only there were some oranges as well so we could compare them side by side....
    Thanks for rel-linking the original link. With the new management data I was pleasantly intrigued and now have a bookmark.
    I'll be skimming and re-reading for quite some time.
    Co incident ly, in the last year of so I've gotten a glimpse of what I (believe) is a totally simple / un scientific explanation of red shift.
    perhaps more nails here as well.
    I live near a well lite at night park, at the mouth of a river, that has a 1/4 mile break water extending into Lake Ontario ( that many people walk, ride bicycles, fish from).
    Very early in the morning, hours before sunrise, when the pier / break water is essentially void of human activity. most espeically on a pristine clear evening, while walking out on the pier towards Quinte, Ontario - , The almost complete darkness while heading north is a stark contast to the view observed while walking south on the pier towards the lights of the park.
    It's only a visual analogy to a way more complex scientific theoretical / mathematical premise. so please to take this post as a disortation of any kind but rather trying to reach for a concept way beyond my intellectual capability, while trying also to relate it for others in the simplest fashion possible, to see how others react to the description.
    Thanks again Mendel.
     
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  20. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah I was doing my morning push-ups a few minutes ago, that 1G never lets up, whatever it is.

    I tried valiantly to read a bit of that Reflections on Relativity. Very commendable that it's freely available online btw. Anyway: I don't have enough brain cells. Very bright guy, and perhaps that what it takes to understand these big-picture things?

    And what to make then of David Levitt, with his expansion explanation? It's seductively convincing, at least "locally", for how gravity manifests, here. But a few dwarf stars, black holes: now what??

    Still, I have a hunch there IS a simple explanation, that can do an end-run around all the complex math and language. :)
     
    #20 Mendel Leisk, Sep 5, 2019
    Last edited: Sep 5, 2019
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