Pushing space

Discussion in 'Astronomy, Exobiology, & Cosmology' started by tashja, Apr 1, 2011.

  1. Motor Daddy ☼☼☼☼☼☼☼☼☼☼☼ Valued Senior Member

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    You don't even know what gravity is, and you are trying to say the sun's gravity provides a force? That's laughable, James.

    I suggest you learn what gravity is before you talk about it. Before you start talking of this magical force of gravity, tell me what it is.

    The sun doesn't "tug" on the earth, that is where you make a fatal mistake.
     
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  3. nitram22 Registered Senior Member

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    Dude where did you learn to count. You traveled 8 years to reach that star. Explain to me how this makes you just 3.5 years older? Or maybe the battery in you calculator went dead on the trip.
    The 'paradox' is for the observer on Earth to who it would appear to be a 12yr trip or thinks he is gazing into the past, when in fact what he sees is current events.
    Departure time: jan. 1, 2011
    Arrival time: jan. 1, 2019
    Sent msg. jan. 1, 2019
    Msg. received: jan. 1, 2023

    All these things happen in realtime.
     
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  5. tashja Registered Senior Member

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    when a planet causes a star to wobble, that is because gravity waves are traveling back and forth between the planet and the star, right? Now, when they finally discover their existence, which unit of wavelenght are they going to use?
     
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  7. Acitnoids Registered Senior Member

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    :scratchead: Where did you hear that?
    .
    Your question seems to be framed in a way that suggests you're more interested in gravity waves than how a planet can cause a star to wobble however, you do seem like a curious person so I'll try and explain the latter and leave the gravity waves to someone else. I'm going to use the Earth and Moon as an example but, the same principle applies to planets and stars (and everything else in an orbit).
    .
    The Moon does not orbit the exact center of the Earth. Instead they both orbit a common point in space known as the barycenter. For simplicity you can think of the barycenter as the position of the pivot point when two different masses balance each other out (on, say, a teeter tauter/seesaw). This pivot point will always be closer to the more massive object.
    .
    The average distance between the center of the Earth and the center of the Moon is 384.4 million meters (r). The Earth has a rest mass of 5.9736 x10+24 Kg (M1) and the Moon has a rest mass of 7.36 x10+22 Kg (M2). To find the barycenter (common center of orbit) you would:
    [THREE STEP PROCESS]
    1) M1/M2 = x
    2) 1+x = y
    3) r/y = barycenter
    .
    Or:
    1) M1+M2 = x
    2) M2/x = y
    3) r*y = barycenter
    .
    This puts the barycenter of Earth and its Moon at 4.6785 million meters from the center of Earth. The radius of the Earth is 6.378 million meters which means this barycenter exists 1.7 million meters below its surface. Because of this the Earth will appear to wobble every time the Moon orbits when, in fact, they're both orbiting the same point. The further the barycenter is from the more massive object, the greater the observed wobble will be.
    .
    http://dictionary.reference.com/browse/barycenter
    http://en.wikipedia.org/wiki/Center_of_mass
     
  8. James R Just this guy, you know? Staff Member

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    I know what gravity is. It's you with the screwy ideas about it.

    Gravity is one of the four fundamental interactions we know of. It can be described as an attractive force (in the Newtonian picture) that is caused by mass. Or it can be described as an effect of the bending of spacetime (in the general relativistic picture) that is caused by mass/energy. The two pictures are, in most circumstances, completely compatible.
     
  9. tashja Registered Senior Member

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    715
    Acitnoids:

    Right. But that action is not instantaneous, isn't? I mean there are gravity waves traveling between the planets carrying the ''force of gravity,'' or propagating the ''curvature of space,'' no?
     
  10. James R Just this guy, you know? Staff Member

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    tashja:

    The answer to that question is a bit complicated.

    In the Newtonian picture of gravity, the force is transmitted instantaneously. However, in the light of relativity we can't have instantaneous action at a distance if some information needs to be transmitted across the distance in order for the action to occur.

    In a steady-state situation such as a planet orbiting a star, the gravitational field of the star is essentially static. Another way to say that is that the star curves spacetime around itself and that spacetime maintains its curvature. An orbiting planet doesn't need to communicate with the star itself to "know" that it needs to travel in a circle. Instead, it just follows the already-establish spacetime curvature at the location where it happens to be at the time.

    Gravity waves come into the picture when something about the gravitational field changes. In that case, you can think of a message being sent out into the space telling it how to adjust its curvature. Gravitational waves, if they exist, are thought to travel at the speed of light.
     
  11. tashja Registered Senior Member

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    Thanks!
     
  12. OnlyMe Valued Senior Member

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    We know a great deal about how objects are affected by gravity.

    What gravity is, what causes gravity, is still theoretical, whether you apply Newton's view or Einstein's, the question of what causes gravity is hypotheses or theory, depending upon what assumptions you begin with.
     
  13. Magneto_1 Super Principia Registered Senior Member

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    You have to remember that this rubber sheet, bowling ball, and marble analogy is used by Einstein as a new model for describing a more general description of Gravitational Interaction.

    In Newton's description of Gravitational Interaction any two mass bodies interact with mutual attraction and that mutual attraction causes each mass body to accelerate towards a common center of that two body system. The mutual attraction is measured with a gradient field strength that is inversely proportional to the square of the distance from the center of the system (\( \frac{1}{d^2}\)). And finally, the gravitational interaction can act over infinitesimal distances (across very small distances), and across infinite space (across very large distances). Newton's Theory of Gravity predicts that over very large cosmological distances the force of interaction is communicated instantaneously. The Einstein Model describes that the interaction is communicated at the speed of light.

    Newtonian Gravitational Force

    \(F = \frac{m_{test}m_{Net}G}{d^2}= \frac{m_{1}m_{2}G}{d^2} -> \frac{kg m}{s^2} \).


    In Einstein's description of Gravitational Interaction any two mass bodies interact with mutual attraction, and that mass can be either: inertial mass or spacetime mass. Although this spacetime mass is not clearly defined in the Einstein Field Equation, the Higgs Boson is a very good candidate for this spacetime mass.

    The essence of Einstein's Gravitational Interaction is that when a first mass body exerts a force on a second mass body, the second body exerts an equal and opposite force on the first body; in accordance with Newton's Second and Third Law of Motion, theory; however that speed of interaction is the speed of light \({c^2}\).

    Likewise, in the vacuum of space, an inertial net mass body exerts an equal an opposite force on the space and time or "spacetime" in that local vicinity of the net mass body. The net Inertial Mass body immersed in the three dimensional space and time around the body is modeled by a spacetime continuum, Stress Energy Tensor (Ideal Gas energy) and curvature, so that is can be said that matter warps the space and time around any Net inertial mass body (\(m_{Net}\)) given by the following equation.

    Einstein Mass-Energy Field Equation

    \(R_{ab} - \frac{1}{2}R g_{ab} + \Lambda g_{ab} = 2 \pi (\frac{T_{ab}} {\frac{1}{4} \frac{c^4}{G}}) = G_{ab} -> m\).

    Source of Curvature - Closed Geodesic - Stress Energy Tensor

    \(T_{ab} = \ (Pressure_{ab})(g_{ab}) = (\frac{1}{4} \frac{c^4}{G})(\frac{G_{ab}}{2 \pi}) = \frac{1}{2}\ m_{Net}{c^2}\)

    \(T_{ab} = (\frac{1}{2 \pi})(\frac{1}{4} \frac{c^4}{G})(R_{ab} - \frac{1}{2}R g_{ab} + \Lambda g_{ab}) -> \frac{kg m^2}{s^2}\).

    What Einstein does here is reintroduce the Aether that he discarded. Because of this modeling of curvature and the warping of space and time it requires that spacetime be modeled as a ideal gaseous material.

    However the Einstein Mass-Energy Field Equation above only predicts where mass curves spacetime and pushes on other objects. For example imagine the Roman Coliseum/Stadium floor to be a giant rubber sheet or carpet. If you were standing at one end of the coliseum on the rubber sheet, and someone else was at the other end of the Coliseum standing on the rubber sheet; although we would both see and experience the sheet bend and curve in our local vicinity. However, our individual curvatures will have no effect on either person standing on the opposite end of the stadium.

    Einstein's equation predicts only how a net inertial mass curving or warping spacetime affects objects in its near gradient field, beyond the influence of curvature another equation is used. This normally where the Schwarzschild Metric comes in.

    \({(s_{S})^2} = (1 - (\frac{r_{S}}{d})){\ (ct)^2} - s^2 = (1 - (\frac{r_{S}}{d})){\ (ct)^2} - \(\frac{d^2} {1 - (\frac{r_{S}}{d})}\) - \ d^2\({a}^2 + \ b^2 \sin^2(a_0))-> \ {m^2} \)

    or infinitesimal change

    \({d(s_{S})^2} = (1 - (\frac{r_{S}}{d})){\ (cdt)^2} - \(\frac{d(d^2)} {1 - (\frac{r_{S}}{d})}\) - \ d^2\(d({a}^2) + \ d(b^2) \sin^2(a_0)) -> \ {m^2} \).

    Similar to Newton's mutual attraction where the strength of the gradient field inversely proportional to the square of the distance from the center of the system (\( \frac{1}{d^2} -> \frac{1}{m^2}\)); Einstein's mutual attraction is measured with a gradient field strength that is inversely proportional to the square of the distance from the center of the system given by the following (\(\frac{1}{2}R - \Lambda -> \frac{1}{m^2}\)).

    So when it is said that space is pushing or exerting a force on you, that means that you also exert an equal and opposite force on the vacuum of spacetime. It can be said that, in accordance with Newton’s “Third Law of Motion;” every Net Inertial Mass (\(m_{Net}\)) body exerts an equal and opposite force on the Spacetime Mass (\(m_{ab}\)) associated with the surrounding medium of Spacetime of which it is evolved and immersed in the universe. In essence, spacetime interacts gravitationally with the inertial mass and mass interacts gravitationally with spacetime.

    The nature of gravity is that every gravitational interaction system is a four (4) dimensional vortex motion, having accelerations or pushing in tangential, radial, and orthogonal directions on any body imersed in the Net Inertial Mass gravitational field.

    \(g_{Gravity} = \frac{F}{m_{test}} = \frac{m_{Net}G}{d^2} -> \frac{m}{s^2}\).
     
  14. tashja Registered Senior Member

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    The quote above sounds interesting. I've never read about gravity been a ''four (4) dimensional vortex motion.''

    Thanks, Magneto_1

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  15. James R Just this guy, you know? Staff Member

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    Neither have I. Where are the vortices, exactly?
     
  16. superstring01 Moderator

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    You probably need to learn the scientific definition of "theory".

    Nothing about science is required to make sense to you (or anybody) for it to be true.

    Which would mean something if entire galaxies didn't cause light to bend around them (no ripples caused by heated gas, just perfect bending). Even better is when a collection of galaxies cause lensing that--in effect--act as a natural magnify glass.

    Must be warm air coming off the sands of all those hot planets! That makes a lot more sense.

    And sometimes if you don't think hard enough you miss the truth entirely.

    So, you're declaring here, right now, that something we've OBSERVED in our own solar system, many times, does not exist? Please clarify, because this is gonna be entertaining. I'm assuming you can answer as to why we can see space bend around Saturn, Jupiter, Neptune and Uranus that is concurrent--precisely--with their mass (not heat).

    Bad attempt at simplification (though, to be sure: The surface bends--but more on that later). The fabric of the universe has no other analogous objects. You can attempt to use the balloon analogy or the surface of the ocean analogy, but none of them work, and so they only serve to confuse the uninitiated mind (see: yourself).

    Now, as to the surface of the ocean, you are aware the "displaced water" actually causes the mean level of the ocean to rise and dip based upon the ridges and trenches? So, if you're sailing over the Marianas Trench you're several hundred feet lower than if you sail over an underwater mountain range. This is due to the fact that oceans react not unlike the winds; the currents shift the surface based on what's underneath them.

    I take it you're a quantum physicist? Any physicist at all? See: Quantum Foam.

    Yes. Please hurry up with those "proofs".

    What does the Sun's gravity do, then?

    You should learn the definition of "fatal", because there is no such mistake made--yet--on this website.

    ~String
     
  17. superstring01 Moderator

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  18. Magneto_1 Super Principia Registered Senior Member

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    James, Rene Descartes in 1633 was the first to apply the theory of vortex motion to gravity. The solar system is a vortex, the earth moon system can be considered a vortex, and the Milky Way Galaxy can be modeled as a vortex.

    With our current understanding of General Relativity we are being force to reconsider and modify Descartes original gravitational vortex theory.

    Quote from Wiki (en.wikipedia.org/wiki/The_World_(Descartes)): "Descartes elaborates on how the universe could have started from utter chaos and with these basic laws could have had its particles arranged so as to resemble the universe we observe today. Once the particles in the chaotic universe began to move, the overall motion would have been circular because there is no void in nature, so whenever a single particle moves, another particle must also move to occupy the space where the previous particle once was. This type of circular motion, or vortex, would have created what Descartes observed to be the orbits of the planets about the sun with the heavier objects spinning out towards the outside of the vortex and the lighter objects remaining closer to the center. To explain this, Descartes used the analogy of a river that carried both floating debris (leaves, feathers, etc.) and heavy boats. If the river abruptly arrived at a sharp bend, the boats would follow Descartes third law of motion and hit the shore of the river since the flow of the particles in the river would not have enough force to change the direction of the boat. However, the much lighter floating debris would follow the river since the particles in the river would have sufficient force to change the direction of the debris. In the heavens, it’s the circular flow of celestial particles, or aether, that causes the motion of the planets to be circular.

    As to the reason why heavy objects on Earth fall, Descartes explained this through the agitation of the particles in the atmosphere. The particles of the aether have greater agitation than the particles of air, which in turn have greater agitation than the particles that compose terrestrial objects (e.g. stones). The greater agitation of the aether forces the particles of air from escaping into the heavens, just as the agitation of air particles forces terrestrial bodies, whose particles have far less agitation than those of air, to descend towards the Earth.

    What Rene Descartes got wrong is that in the heavens the flow of celestial particles, or aether, that causes the motion of the planets is mostly elliptical and only sometimes circular. Actually the gravitation theory that Descartes posits fits in more with the concepts of "Dark Matter" than they do for solar system gravity.
     
  19. AlphaNumeric Fully ionized Moderator

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    Magneto doesn't know the first thing about relativity. Don't trust anything he says about it unless you have heard it from a reputable source. Do a search for the rest of his posts (he currently has less than 20). His first dozen or so were in a discussion with me where he demonstrated profound ignorance of relativity, despite the fact he's written a book (in 3 volumes!!) supposedly about it. The stuff in his large post further up this page contains numerous errors, which I've corrected him on previously. The fact he's still spouting them shows how intellectually dishonest he is.

    Normally I wouldn't jump into a thread in this manner but he's simply dishonest for trying to swindle people out of money by writing that crap and you're someone who looks like they actually want to find stuff out.
     
  20. OnlyMe Valued Senior Member

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    As used in science, a theory is an explanation or model based on observation, experimentation, and reasoning, especially one that has been tested and confirmed as a general principle helping to explain and predict natural phenomena.

    The use of the word truth in the place of the word theory can be misleading.

    The original quote, at least the involved sentence, involved a description of orbits and curved space, as defined by the general theory of relativity.

    It might have been clearer had I said, "According to the theory of general relativity...", rather than, "In truth...".
     
  21. superstring01 Moderator

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    Out of curiosity, are you attempting to use Descartes to discredit modern astrophysics?

    ~String
     
  22. Acitnoids Registered Senior Member

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    I don't want to seem rude. The reason I didn't reply to your direct questions is because James R already answered them.
     
    Last edited: Apr 8, 2011
  23. Acitnoids Registered Senior Member

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    Correct. Bad choice of words on my part. I'm usually pretty good about that stuff but, everyone slips from time to time. Your discription of a scientific theory in post #7 is another good example of a misleading statement

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    .
    How does one prove a theory exactly (rhetorical question)?
     
    Last edited: Apr 8, 2011

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