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Thread: Question about gravity

  1. #1 Question about gravity 
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    Scenario: There are two motionless and solid (pure solid - no gapes even on sub-atomic level and lower) bodies of matter, of equal size and shape (perfectly spherical in this case), within a hypothetical empty universe (other than these two objects).

    Question: Will these two objects have the property gravity, and in turn attract each other once the scenario is initiated and they are of some distance apart? Remember, they are initially motionless.

    P.S. if i am missing some variable within this hypothetical please let me know.

    thx in advance


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  3. #2  
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    If your question is whether or not these two objects will attract each other then the answer is yes. This is true based on the law of universal gravitation. The size of the force is proportional to the sum of the two masses and inversely proportional to the square of the distance between them. So if these two hypothetical spheres abide by the same laws of physics of this universe they will attract each other.


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  4. #3  
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    So gravity happens even when objects have 0 energy, that is, it is a property that can create energy? that would be a problem. Initially these bodies would have 0 energy, but once the scenario is initiated they would then gain energy by means of gravity?

    ~im m1cojakle
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  5. #4  
    Moderator Moderator Dishmaster's Avatar
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    No, gravity is a form of energy (potential energy) depending on the mass and the distance of the two bodies.
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  6. #5  
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    Quote Originally Posted by ttcfraser
    So gravity happens even when objects have 0 energy, that is, it is a property that can create energy? that would be a problem. Initially these bodies would have 0 energy, but once the scenario is initiated they would then gain energy by means of gravity?

    ~im m1cojakle
    The bodies have mass and therefore energy. There is also a potential energy in the gravitational field by virtue of the separation of the bodies.

    That is exactly what happens when a ball falls. The potential energy that comes with height is converted to kinetic energy by virtue of falling, and into heat energy after impact and bit of bouncing.

    It is not a problem. It is called conservation of energy.
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  7. #6  
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    Sometimes this initial configuration energy is hard to visualize so let me give two other thought experiments that may help with this understanding.

    1) I will use the same setup with the two perfect masses but this time lets turn gravity off. Instead I'm going to stretch a spring between the two masses. Now before I let go there is no motion and therefore no kinetic energy. But in the act of setting up this thought experiment we had to apply some work (force x distance or ) to stretch the spring. Therefore there is some configuration energy in the form of potential energy in the spring. The point here is when we visualize a setup there may be some configuration energy in our picture.

    2) Let's turn gravity back on an start with one ball of mass . To turn this picture into your set up I need to break the mass into two and then separate them. (Because this is not the chemistry forum we will neglect the energy required to do the "breaking") During the act of separating the masses I will have to do some work. This is the inherent configuration energy that was present in your initial setup.

    Hope this helps
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  8. #7 Re: Question about gravity 
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    Quote Originally Posted by m1cojakle
    Scenario: There are two motionless and solid (pure solid - no gapes even on sub-atomic level and lower) bodies of matter, of equal size and shape (perfectly spherical in this case), within a hypothetical empty universe (other than these two objects).

    Question: Will these two objects have the property gravity, and in turn attract each other once the scenario is initiated and they are of some distance apart? Remember, they are initially motionless.

    P.S. if i am missing some variable within this hypothetical please let me know.

    thx in advance
    There is truly no such entity as motion or a physical solid object. However, if you had an object and nothing else you would have an object in space because space is that 'nothing else'. At least that is where experimental evidence points towards. Unless space has kind of an aether that has very unusual properties.

    When there is only one object motion is meaningless. The object still emits light at the velocity of C. So if you can imagine if the object moved, even though it would be impossible to tell, the light would still be emitted at C.

    As soon as you include the second object, the first stage to relative meaning begins.

    The objects would be more likely to be attracted or repelled due to electrical charge then the actual force of gravity. However, for the sake of your scenario, gravity - as the mainstream successful theories explain - would attract the objects.

    but like I said there is no such thing as an object anyway like we think their is objects. Objects are only a mental construct formed out of compound events. We paint the world with shape, texture, color, and things like this, all sorts of things that have very little meaning or application at an atomic scale.

    From what I understand science knows, I would say, we most likely do not know enough about gravity as it is right now in order to answer your question to a full satisfaction.
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  9. #8 Re: Question about gravity 
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    Quote Originally Posted by arkain101
    Quote Originally Posted by m1cojakle
    Scenario: There are two motionless and solid (pure solid - no gapes even on sub-atomic level and lower) bodies of matter, of equal size and shape (perfectly spherical in this case), within a hypothetical empty universe (other than these two objects).

    Question: Will these two objects have the property gravity, and in turn attract each other once the scenario is initiated and they are of some distance apart? Remember, they are initially motionless.

    P.S. if i am missing some variable within this hypothetical please let me know.

    thx in advance
    There is truly no such entity as motion or a physical solid object. However, if you had an object and nothing else you would have an object in space because space is that 'nothing else'. At least that is where experimental evidence points towards. Unless space has kind of an aether that has very unusual properties.

    When there is only one object motion is meaningless. The object still emits light at the velocity of C. So if you can imagine if the object moved, even though it would be impossible to tell, the light would still be emitted at C.

    As soon as you include the second object, the first stage to relative meaning begins.

    The objects would be more likely to be attracted or repelled due to electrical charge then the actual force of gravity. However, for the sake of your scenario, gravity - as the mainstream successful theories explain - would attract the objects.

    but like I said there is no such thing as an object anyway like we think their is objects. Objects are only a mental construct formed out of compound events. We paint the world with shape, texture, color, and things like this, all sorts of things that have very little meaning or application at an atomic scale.

    From what I understand science knows, I would say, we most likely do not know enough about gravity as it is right now in order to answer your question to a full satisfaction.
    No, not to a full satisfaction unfortunately. However, these posts have been helpful in light of my recent discoveries. It seems that "gravity" is an innate quality that all "physical" bodies have, although the apparent cause of such a phenomena is still up in the air, for now.

    As well, "Mental constructs" aside it is still necessary to address substances of the sub-atomic level with the same 3-Dimensional perspective we use to assess the macro physical world. It must be understood that all matter will have the property of 3-dimensional and thus be subject to the constraints of physical causality, or rather "compound events." In light of that tidbit, we can assume that gravity - whatever it is - will have the same proprietary quality as particles of matter.

    In any case, the reason I put forth this scenario was to help myself inquire into the question of whether or not gravity is a phenomena brought about as an illusion of space-time or whether or not it is the result of something undiscovered. That is, if two completely solid "physical objects" were in a completely empty universe, since there is nothing between them they would have no reason to attract each other; such would be an obvious conjecture, but unfortunately this is not the case, and these two objects will attract each other. Why then is this the case...?

    There are 3 possible scenarios for a cause for the property of gravity..

    1) The property gravity is an illusion brought about by some space-time distortion

    2) Particles of matter, being affected by gravity as they all are, are of the same nature as gravity, i.e. they have the same "non-real" properties as space-time, and thus can interact with each other by means of gravity.

    3) Something else
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  10. #9  
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    As well, "Mental constructs" aside it is still necessary to address substances of the sub-atomic level with the same 3-Dimensional perspective we use to assess the macro physical world. It must be understood that all matter will have the property of 3-dimensional and thus be subject to the constraints of physical causality, or rather "compound events." In light of that tidbit, we can assume that gravity - whatever it is - will have the same proprietary quality as particles of matter.
    However, everything that is matter at the micro scale lives in a 1 dimension world. That is, objects only move one way, through one line. They only subject forces one way through 1 line.

    So what really is 3d? waves follow that path, but not much else.

    Aha it hit me.. Forces can travel 3d However, they only act 1d
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  11. #10 Re: Question about gravity 
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    Quote Originally Posted by m1cojakle
    Question: Will these two objects have the property gravity, and in turn attract each other once the scenario is initiated and they are of some distance apart? Remember, they are initially motionless.
    No they won't, I think.

    Steve
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  12. #11  
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    heh, i hope you don't live in a 2 story house steve.

    gravity might not be real, but its effect is.
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