Audiowriter Posted September 19, 2013 Share Posted September 19, 2013 (edited) From certain sources I have been led to believe that the reason for gravity in the universe, specifically for example, our solar system, is due to mass warping space-time and this interaction is what causes the planets to orbit the sun in such a predictable path. At the same time, I am also led to believe that this same effect of mass on the fabric of space-time is responsible for planets, specifically the earth, to retain an atmosphere and have the observable effects on objects - to be what we consider gravity here on the surface. Is this a result of the fabric of space-time forcing objects toward the surface (or center) of the mass of the earth - or, is surface gravity created simply because of the incredible speed or motion of the mass (of the earth itself) zooming through space-time forcing everything near enough toward its center? It seems to me that if the aether of space-time itself is what forces objects, including molecules of an atmosphere, toward the surface of any massive body, this would suggest that their must be some material property to the aether of space-time. If this is true, then if a space ship were to be in motion through seemingly empty space and were to purposely depressurize and "roll down a window" - any observer in a spacesuit inside the space ship should be able to tell if the window was open or closed by means of any resulting friction or disturbances, such as "wind" or aether particles flying in through the open window. But if space is an absolute vacuum, there would be no way for the observer in the space ship to tell if the window was open or closed, because at any rate of speed, there would be nothing to flow into the open window to cause disturbance. I am a novice at physics, but my mind never rests. Any responses to my oddly described questions and statements would be appreciated. AudioWriter Edited September 19, 2013 by Audiowriter Link to comment Share on other sites More sharing options...
ajb Posted September 19, 2013 Share Posted September 19, 2013 From certain sources I have been led to believe that the reason for gravity in the universe, specifically for example, our solar system, is due to mass warping space-time and this interaction is what causes the planets to orbit the sun in such a predictable path. At the same time, I am also led to believe that this same effect of mass on the fabric of space-time is responsible for planets, specifically the earth, to retain an atmosphere and have the observable effects on objects - to be what we consider gravity here on the surface. The best theory of classical gravity that we have is Einstein's general relativity and indeed that describes gravity as the local geometry of space-time. Loosely, anything with mass and or energy courses space-time to local warp and this is then seen as gravity. Is this a result of the fabric of space-time forcing objects toward the surface (or center) of the mass of the earth - or, is surface gravity created simply because of the incredible speed or motion of the mass (of the earth itself) zooming through space-time forcing everything near enough toward its center? This is not the way to think of it at all. First velocity is always relative to something else so the notion of an object zooming through space-time is ambiguous. I'll comment more in a moment. It seems to me that if the aether of space-time itself is what forces objects, including molecules of an atmosphere, toward the surface of any massive body, this would suggest that their must be some material property to the aether of space-time. The space-time aether would provide an absolute frame of reference that we could all agree on. This does not fit well with modern physics. All and any frames are equally as good. One does not think of space-time as a material object, but it is a dynamic thing and can change in time. If this is true, then if a space ship were to be in motion through seemingly empty space and were to purposely depressurize and "roll down a window" - any observer in a spacesuit inside the space ship should be able to tell if the window was open or closed by means of any resulting friction or disturbances, such as "wind" or aether particles flying in through the open window. Right he might do if it were true, but we have no reason to think this is the case given general relativity. The trouble is that if he did measure something then he could claim to be moving at an absolute velocity buy using this stream of particles. This again, just does not sit well with modern physics. There is no reason to think of space-time in quite the way you have. But if space is an absolute vacuum, there would be no way for the observer in the space ship to tell if the window was open or closed, because at any rate of speed, there would be nothing to flow into the open window to cause disturbance. In your scenario there is no vacuum, but a sea of aether particles! I hope that helps a little. Link to comment Share on other sites More sharing options...
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