Is gravity really a push?

Discussion in 'Science' started by Ready Aim Fire, Feb 11, 2014.

  1. Wolverine

    Wolverine New Member Past Donor

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    If it is not detectable, then it is moot... for all we know things are getting smaller and the expansion of space is an illusion.

    We can make up all sorts of things.
     
  2. Ready Aim Fire

    Ready Aim Fire New Member

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    Yep, pretty much a worthless thread. But did it change or bend your thinking a bit?
     
  3. Wolverine

    Wolverine New Member Past Donor

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    With due respect, not really. If X is not measurable, then it really is a moot thought.

    Objects could be getting bigger or smaller, there could also be an invisible pink unicorn behind me (that does not appear in mirrors or video) that disappears when I turn around.
     
  4. Ready Aim Fire

    Ready Aim Fire New Member

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    Better watch out. That one horn can do some damage if you spook him. One poked me in the left cheek... Now I have 2 a**holes.
     
  5. Ready Aim Fire

    Ready Aim Fire New Member

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    Since no one really knows anything about where gravity comes from, it seems to be the best explanation I've heard... even if it can't be proven.
     
  6. Wolverine

    Wolverine New Member Past Donor

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    If it cannot be proven, it is moot.

    Einstein's explanation of gravity, the curvature of spacetime, is observable.
     
  7. Ready Aim Fire

    Ready Aim Fire New Member

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    I don't know. I don't think that you can prove that we have CHOICE. I don't believe a vegetable, be it human or tomato, chose to be a vegetable.
    I'm only talking about things growing by 0.000000001231%/sec/sec. It's really not that much even though it's accelerating.
     
  8. Wolverine

    Wolverine New Member Past Donor

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    Doesn't matter, you are making stuff up and expect people to accept is as a revelation.
     
  9. Ready Aim Fire

    Ready Aim Fire New Member

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    Why do you care anyway. My math is dead wrong!!!!
     
  10. 10A

    10A Chief Deplorable Past Donor

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    If the Earth were expanding in proportion to gravitational acceleration, then points at the Earth's surface would be accelerating at one rate, while points closer to the Earth's center would accelerate at a different rate (gravitation is less the closer you are to the Earth's center). Gravity differences are measurable even on the Earth's surface, say the difference between standing on a mountain or on the beach. To maintain a constant proportion between gravity and acceleration, that means the distance between the top of a mountain and the beach would forever increase. The distance between the beach and the top of a hill (say 1/10th the height of the mountain) would also increase, but at less of a rate than the mountain to maintain the exact proportion to gravitation (if force were proportional to velocity that wouldn't necessarily be the case, but unfortunately for this theory force is proportional to acceleration). I won't go into the ever increasing kinetic energy.

    That means our tape measure has to "know" when it is measuring a mountain vs. a hill vs the length of the beach. Presumably our magical tape measure would shrink to nothing at the center of the Earth, where there is no net gravitational force.

    Now this expanding at the rate of gravitational acceleration has only been presented as Earth centric. Other bodies in the universe, or in our own solar system, have different masses and different gravitational forces. Is Earth the special thing in the universe that causes everything in the universe to expand at it's special gravitational acceleration? Why not the Moon, or the Sun? If we want to make this new expansion "law" work, then I presume that the Moon would have to expand at it's gravitational acceleration. That is certainly less than the Earth's. Even if the universe expanded proportionally to Earth's gravitation, the radius of the Moon would add to that and though the Moon might not get bigger (it would probably get smaller actually under this "law"), it would get closer.

    Sorry, but for this law to work it has to have much better symmetry, not be Earth centric, and has to deal with energy issues and known constants such as the speed of light, and I didn't even touch on thermodynamic problems.
     
  11. RevAnarchist

    RevAnarchist New Member Past Donor

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    With all due respect, either I misunderstood your reply or your statement (in the above excerpt from your post) is incorrect. Gravity increases as you near the center of a mass, and time 'runs' slower.
    You may be thinking about the dead center where gravity would be 'pulling' in all directions evenly?


    reva
     
  12. iAWESOME

    iAWESOME New Member

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    Gravity doesn't really exist. Its not a force, just the result of spacetime being distorted.
     
  13. iAWESOME

    iAWESOME New Member

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  14. Hoosier8

    Hoosier8 Well-Known Member Past Donor

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    Nothing scientific but IMO gravity is the bending of space by matter that causes the difference in space that causes the push. The more matter, the bigger the push. An expanding earth would simply expand the push.
     
  15. Ready Aim Fire

    Ready Aim Fire New Member

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  16. Ready Aim Fire

    Ready Aim Fire New Member

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  17. 10A

    10A Chief Deplorable Past Donor

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    The closer you get to the center of mass within a body, the more gravitational force decreases (and acceleration, since F=ma). I would be kind of funny if net forces increased until you get to the center of the Earth and then "poof!" went instantly to zero...that would definitely be a non-linear function. It might be fun to think about what would happen to your body if your head was in the center and your body was outside the center.

    The description is governed by Gauss's law, which is more familiar in its form as one of Maxwell's equations (electrical laws). Gauss's law for gravity essentially states that outside a mass you can treat the whole thing is a single point mass (note that Newton's law of gravity does not do this, it assumes a point mass). It also states that when you are within a uniform distributed mass, the strength of the gravitational field decreases in proportion to the distance from the center of mass.

    The law kind of goes like this: You create an imaginary enclosed spherical surface going through a test point and around the center of mass. The gravitational flux is only dependent upon the density and volume of whats inside that surface, not on what's outside. If you are say, halfway between the surface of the Earth and the center, you create an imaginary spherical surface at that distance and calculate the gravitational flux based on what's inside that shell. It doesn't matter what is outside. Note that you can use Gauss's law anywhere within the field not just around a the center of mass, but we'll bypass what that really means.

    Another result of this law is that if you were within a hollow shell of mass, there would be no net gravitational forces. Again, we create an imaginary surface inside the shell. There's nothing inside the shell, so net forces are zero. Outside the shell however, an imaginary surface would contain the entire shell, and the mass of the shell can be treated as a point mass at the center...which is empty!

    Time dilation doesn't depend on the gravitational force, it only depends on the potential, with the force being the gradient of the potential. That gradient decreases to zero as you move from the surface to the center of the Earth. The potential does continue to increase, so you are correct time will still run slower.

    I can see where the confusion comes from given Newton's law of gravitation, but understand Newton's law only applies to point masses, or objects we can model as point masses due to Gauss's law.
     

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