Pliny Posted October 26, 2011 Author Report Posted October 26, 2011 Long story short: if you are traveling towards a light source, each subsequent pulse of light from that source has less distance to cover before it reaches you. So you observe them to reach you more frequently than they are emitted. Converse true for if you are moving away from the source. Your short story suggests, that if I am traveling at half the speed of light then light from sources I am moving away from, relative to myself, will be traveling at half the speed of light and light from sources I am approaching, relative to me, will be moving at one and a half times the speed of light. Let's forget the medium light is traveling through for now. Doesn't general relativity conclude that light relative to any point regardless of the speed must always be traveling at a constant? In other words, if I am traveling at half the speed of light, the light around me is still traveling at light speed and I am considered motionless relative to it. Quote I want to be in the class that ensures the classless society remains classless.
ToadBrother Posted October 26, 2011 Report Posted October 26, 2011 Your short story suggests, that if I am traveling at half the speed of light then light from sources I am moving away from, relative to myself, will be traveling at half the speed of light and light from sources I am approaching, relative to me, will be moving at one and a half times the speed of light. Let's forget the medium light is traveling through for now. Doesn't general relativity conclude that light relative to any point regardless of the speed must always be traveling at a constant? In other words, if I am traveling at half the speed of light, the light around me is still traveling at light speed and I am considered motionless relative to it. Welcome to Special Relativity. The speed of light is the same for all observers, regardless of inertia or reference frame. It is probably one of the more obviously counter-intuitive aspects of Relativity, and yet has been confirmed many times. Quote
Pliny Posted October 27, 2011 Author Report Posted October 27, 2011 Welcome to Special Relativity. The speed of light is the same for all observers, regardless of inertia or reference frame. It is probably one of the more obviously counter-intuitive aspects of Relativity, and yet has been confirmed many times. That being true then, and you appreciatively put it in better words than I, how is a perception of red shift and blue shift possible? Quote I want to be in the class that ensures the classless society remains classless.
Bonam Posted October 27, 2011 Report Posted October 27, 2011 That being true then, and you appreciatively put it in better words than I, how is a perception of red shift and blue shift possible? Already answered. Quote
Pliny Posted October 27, 2011 Author Report Posted October 27, 2011 This is so absurd, it's not even wrong. The reason the planets orbit the sun is because the sun's gravity warps space, turning a straight line into a curved one. If the sun were to disappear right now, in eight minutes (presuming gravity propagates at the speed of light), the Earth would start moving in a straight line. Where the hell do you get the "universe is spinning" notion from? What would that even mean? I wasn't being serious but now that you are so hept up about it maybe I'll take a second look. Quote I want to be in the class that ensures the classless society remains classless.
Pliny Posted October 27, 2011 Author Report Posted October 27, 2011 Already answered. But....but.... but...how do I see a shift if light is traveling at the same speed relative to myself from all sources. Sound is traveling through a medium - air, and the medium is what causes the frequency shift as the source moves away. Now you said that, "if I am approaching a source of light, each pulse of light has less distance to cover before it reaches me. So you observe them to reach you more frequently than they are emitted. Converse true for if you are moving away from the source." That does not jibe with special relativity. Light from all sources travels, relative to me, at the same speed, there can be no more "frequently emitted pulses of light" I could observe from anywhere. Quote I want to be in the class that ensures the classless society remains classless.
ToadBrother Posted October 27, 2011 Report Posted October 27, 2011 That being true then, and you appreciatively put it in better words than I, how is a perception of red shift and blue shift possible? For goodness sakes, Pliny, the Doppler Effect has to do with how waves reach an observer. I don't know how you're confused about this as a number of people here have explained over and over and over again. Quote
ToadBrother Posted October 27, 2011 Report Posted October 27, 2011 But....but.... but...how do I see a shift if light is traveling at the same speed relative to myself from all sources. Sound is traveling through a medium - air, and the medium is what causes the frequency shift as the source moves away. Now you said that, "if I am approaching a source of light, each pulse of light has less distance to cover before it reaches me. So you observe them to reach you more frequently than they are emitted. Converse true for if you are moving away from the source." That does not jibe with special relativity. Light from all sources travels, relative to me, at the same speed, there can be no more "frequently emitted pulses of light" I could observe from anywhere. The speed of light is not infinite. That's what you seem to be suggesting, because that's the only way what you're saying makes any sense. Since the speed of light is finite, it takes time for a photon to cover a particular distance. Quote
Pliny Posted October 27, 2011 Author Report Posted October 27, 2011 (edited) Pliny, the energy involved in applying a force is given by the following equation: Energy = force * distance If the object that the force is being applied to doesn't move any distance, no energy is spent. This is basic grade 8 physics here. The magnet is sitting still, not moving. Therefore no energy is expended. So if I push against a wall and neither the wall nor I move any distance then no energy has been expended, although I might break out into a sweat. That's a mathematical formula for determining the amount of energy expended to move an object a specified distance. If the distance is zero of course mathematically I get an answer of zero. I may apply a force but not enough to overcome the inertia of the mass. Does that mean zero energy has been expended? But in fact, a magnet on a fridge does not drop to the floor. The force of gravity, is pulling it's mass toward the floor. The properties of the magnet are keeping it stationary resisting the pull of gravity. In effect, it is similar to me holding a ball outward in my hand, I am expending energy by preventing the ball from dropping. When I run out of energy and can no longer hold the ball it drops to the ground. Essentially, a state of equilibrium of forces is attempted to be achieved by all objects, it takes energy to maintain them in a state out of equilibrium. All objects on Earth to reach equilibrium remain on the ground. An energy is applied to move it off the ground and it must be continuously applied to keep it off the ground in a state out of equilibrium. The magnet behaves as any other object that is put on a vertical surface. It falls off, unless it is in contact with a ferrous metal, in which case it does not. The formula tells me no energy is being expended. The magnet is moving 0 distance. Is this the case? If I have two magnets and hold them apart, keeping their polar opposites from moving toward each other. I must use force. How long I can apply the force to keep them apart is the amount of energy I have to keep them apart. I don't see how that energy can be zero??? Edited October 27, 2011 by Pliny Quote I want to be in the class that ensures the classless society remains classless.
Pliny Posted October 27, 2011 Author Report Posted October 27, 2011 The speed of light is not infinite. That's what you seem to be suggesting, because that's the only way what you're saying makes any sense. Since the speed of light is finite, it takes time for a photon to cover a particular distance. If an observer were traveling at light speed would light appear to be traveling at light speed relative to that observer or would it appear stopped. Doesn't special relativity essentially imply that the speed of light is infinite since it's speed is constant relative to all observers - or do you exclude an observer traveling at light speed or one at half the speed of light. Quote I want to be in the class that ensures the classless society remains classless.
Pliny Posted October 27, 2011 Author Report Posted October 27, 2011 (edited) For goodness sakes, Pliny, the Doppler Effect has to do with how waves reach an observer. I don't know how you're confused about this as a number of people here have explained over and over and over again. I am not confused by the Doppler effect. I am confused as to how it applies to light as regards special relativity. The Doppler effect is created by a moving source where the signal is compressed in the direction of a moving source and thus the frequency sounds higher as it approaches and gets lower as it moves away. It is the compression of the sound by the motion of the source as it moves toward an observer that makes it's frequency seem higher. The sound being emitted by the source is catching up to the sound already emitted, so to speak. If the source is not moving all listeners will hear the same frequency. In special relativity, light is moving at the same speed relative to all observers. The light from the source is then traveling away at the same speed in all directions. There is no compression of light in the direction of the source as it moves. It moves the same speed away in all directions as though the source is motionless. That is the claim of special relativity. The source being motionless means there can be no Doppler Effect, that is to say, shift in frequency to observers from a motionless source. Intuitively, we think the star is moving away from us thus the Doppler Effect seems a plausible concept that can be applied to light frequency. The light emitted as the source moves towards a direction is catching up to the light already emitted, in the same manner as sound. Thus a frequency shift should be observable. Why everyone has been trying to tell me that over and over escapes me. But if light travels the same speed relative to all observers as special relativity states, it violates the theory of special relativity to say a frequency shift can be observable. Edited October 27, 2011 by Pliny Quote I want to be in the class that ensures the classless society remains classless.
Wild Bill Posted October 27, 2011 Report Posted October 27, 2011 (edited) If an observer were traveling at light speed would light appear to be traveling at light speed relative to that observer or would it appear stopped. Doesn't special relativity essentially imply that the speed of light is infinite since it's speed is constant relative to all observers - or do you exclude an observer traveling at light speed or one at half the speed of light. First of all, unless someone invents a Star Trek space warp drive it is impossible to travel at light speed. Einstein's simple equation of E=MxC^2 means that Energy equals Mass times the Speed of Light Squared! If you understand this and dig a bit deeper you realize that this means that the faster you go the more your Mass increases, which means you need more energy to accelerate even faster. You may start at 100 lbs of Mass but at 20% of light speed you may have 130 lbs. The rate of increase is also not linear but follows a curve. When you get close to the speed of light your apparent Mass becomes so great that there is no longer enough energy in the Universe to make you go any faster! But for purposes of argument let's assume that your model is real. If an observer were traveling at light speed and measured the speed of light he would get the exact same value of any other observer traveling at any different speed. This has been stated over and over in this thread but you either just can't or won't accept it or you are just trolling us! If you think about this long enough you will come to understand that there is only one way such a thing could be true. The observer's time rate must be FAR slower than ours! To him, everything is perfectly normal but to US he is moving so slow as to look like a fly in amber. The speed of light hasn't changed! It is still exactly the same value as measured by any other observer traveling at any other speed! The CLOCKS move faster or slower! The rate of time passing is different for each observer but there's no way for any observer to be able to know that. To him, it takes the same time to boil water for a cup of tea as anybody else, anywhere. I can't comment on your suggestion stating that the speed of light is infinite 'cuz I have absolutely no idea of where that came from or how it is relevant! No one, including Einstein, has ever said that the speed of light is infinite! You're breaking new territory here, Pliny. You should marry Betsy. Edited October 27, 2011 by Wild Bill Quote "A government which robs Peter to pay Paul can always depend on the support of Paul." -- George Bernard Shaw "There is no point in being difficult when, with a little extra effort, you can be completely impossible."
Pliny Posted October 27, 2011 Author Report Posted October 27, 2011 (edited) First of all, unless someone invents a Star Trek space warp drive it is impossible to travel at light speed. Einstein's simple equation of E=MxC^2 means that Energy equals Mass times the Speed of Light Squared! If you understand this and dig a bit deeper you realize that this means that the faster you go the more your Mass increases, which means you need more energy to accelerate even faster. You may start at 100 lbs of Mass but at 20% of light speed you may have 130 lbs. The rate of increase is also not linear but follows a curve. When you get close to the speed of light your apparent Mass becomes so great that there is no longer enough energy in the Universe to make you go any faster! But for purposes of argument let's assume that your model is real. If an observer were traveling at light speed and measured the speed of light he would get the exact same value of any other observer traveling at any different speed. This has been stated over and over in this thread but you either just can't or won't accept it or you are just trolling us! If you think about this long enough you will come to understand that there is only one way such a thing could be true. The observer's time rate must be FAR slower than ours! To him, everything is perfectly normal but to US he is moving so slow as to look like a fly in amber. The speed of light hasn't changed! It is still exactly the same value as measured by any other observer traveling at any other speed! The CLOCKS move faster or slower! The rate of time passing is different for each observer but there's no way for any observer to be able to know that. To him, it takes the same time to boil water for a cup of tea as anybody else, anywhere. I can't comment on your suggestion stating that the speed of light is infinite 'cuz I have absolutely no idea of where that came from or how it is relevant! No one, including Einstein, has ever said that the speed of light is infinite! You're breaking new territory here, Pliny. You should marry Betsy. Hey Wild Bill! That's funny. Special relativity theorizes that "light travels at a constant velocity relative to all observers". I didn't have an argument from anyone about that. So what does it mean when special relativity states that "light moves at a constant velocity relative to all observers"? It is not qualified by the statement "unless the observers are moving; in which case it's velocity would be calculated as being plus or minus the relative velocity of the observers" - even though you would intuitively think that. So adding that qualifier invalidates the statement special relativity makes that light moves at a constant velocity relative to all observers. Isn't that saying that the velocity of an observer relative to light must be zero, and the velocity of all observers relative to light must be zero? But for purposes of argument let's assume that your model is real. If an observer were traveling at light speed and measured the speed of light he would get the exact same value of any other observer traveling at any different speed. This has been stated over and over in this thread but you either just can't or won't accept it or you are just trolling us! That makes sense but we are talking about relativity theory here. Observers would have to be measuring light realtive to other things and the statment is that "light travels at constant speed relative to all observers" not relative to other things. Edited October 27, 2011 by Pliny Quote I want to be in the class that ensures the classless society remains classless.
Wild Bill Posted October 27, 2011 Report Posted October 27, 2011 Hey Wild Bill! That's funny. Special relativity theorizes that "light travels at a constant velocity relative to all observers". I didn't have an argument from anyone about that. So what does it mean when special relativity states that "light moves at a constant velocity relative to all observers"? It is not qualified by the statement "unless the observers are moving; in which case it's velocity would be calculated as being plus or minus the relative velocity of the observers" - even though you would intuitively think that. So adding that qualifier invalidates the statement special relativity makes that light moves at a constant velocity relative to all observers. Isn't that saying that the velocity of an observer relative to light must be zero, and the velocity of all observers relative to light must be zero? That makes sense but we are talking about relativity theory here. Observers would have to be measuring light realtive to other things and the statment is that "light travels at constant speed relative to all observers" not relative to other things. I'm sorry Pliny but I just give up! I'm not sure if you're just yanking our chains or that in real life you write science articles for WatchTower magazine! Life's too short! Quote "A government which robs Peter to pay Paul can always depend on the support of Paul." -- George Bernard Shaw "There is no point in being difficult when, with a little extra effort, you can be completely impossible."
kimmy Posted October 28, 2011 Report Posted October 28, 2011 (edited) So if I push against a wall and neither the wall nor I move any distance then no energy has been expended, although I might break out into a sweat. That's a mathematical formula for determining the amount of energy expended to move an object a specified distance. If the distance is zero of course mathematically I get an answer of zero. I may apply a force but not enough to overcome the inertia of the mass. Does that mean zero energy has been expended? If you lean a stick against a wall, the stick is applying force to the wall. Possibly for hours, days, or even many many years. Does that mean the stick is generating infinite energy? No, Pliny, it does not. And as usual the problem here is that you just don't understand what you're talking about. You're expending energy by pressing against the wall-- contracting your muscles uses chemical energy, and generates heat. But you're not generating energy any more than the stick leaning against the wall is generating energy. But in fact, a magnet on a fridge does not drop to the floor. The force of gravity, is pulling it's mass toward the floor. The properties of the magnet are keeping it stationary resisting the pull of gravity. In effect, it is similar to me holding a ball outward in my hand, I am expending energy by preventing the ball from dropping. When I run out of energy and can no longer hold the ball it drops to the ground. And holding the ball at constant height is no different from a table holding a ball at constant height. Is the table burning energy? If a ball sits on a table for 100 years, does that mean that the table has generated an incalculable amount of energy during that time? No. Essentially, a state of equilibrium of forces is attempted to be achieved by all objects, it takes energy to maintain them in a state out of equilibrium. Nope. All objects on Earth to reach equilibrium remain on the ground. An energy is applied to move it off the ground yep and it must be continuously applied to keep it off the ground in a state out of equilibrium. nope The magnet behaves as any other object that is put on a vertical surface. It falls off, unless it is in contact with a ferrous metal, in which case it does not. The formula tells me no energy is being expended. The magnet is moving 0 distance. Is this the case? yep If I have two magnets and hold them apart, keeping their polar opposites from moving toward each other. I must use force. How long I can apply the force to keep them apart is the amount of energy I have to keep them apart. I don't see how that energy can be zero??? If you put a brick between two magnets to keep them apart, is the brick generating energy? Nope. Your muscles are burning chemical energy while you're holding the magnets in place, but that energy isn't being added to the system of magnets. It's being lost as heat. It's not being added to the system of the magnets. -k Edited October 28, 2011 by kimmy Quote (╯°□°)╯︵ ┻━┻ Friendly forum facilitator! ┬──┬◡ﾉ(° -°ﾉ)
kimmy Posted October 28, 2011 Report Posted October 28, 2011 So what does it mean when special relativity states that "light moves at a constant velocity relative to all observers"? It is not qualified by the statement "unless the observers are moving; in which case it's velocity would be calculated as being plus or minus the relative velocity of the observers" - even though you would intuitively think that. So adding that qualifier invalidates the statement special relativity makes that light moves at a constant velocity relative to all observers. Isn't that saying that the velocity of an observer relative to light must be zero, and the velocity of all observers relative to light must be zero? No, Pliny... If I'm driving my spaceship at a speed of c/2 and there is an observer directly in front of me... the light from my headlights is approaching him at c and I am approaching him at c/2. From my point of view, the light from my headlights is also moving at the speed of light, and the observer is coming towards me at .5c. You might intuitively think "she's moving at .5c and from her point of view light is moving at c so from the point of view of somebody watching, the net effect should be .5c + c = 1.5c". But you'd be mistaken, because you'd be mixing information from 2 different frames of reference. -k Quote (╯°□°)╯︵ ┻━┻ Friendly forum facilitator! ┬──┬◡ﾉ(° -°ﾉ)
Bonam Posted October 28, 2011 Report Posted October 28, 2011 Dunno how you had the patience for that kimmy, I just gave up a few posts ago Quote
GostHacked Posted October 28, 2011 Report Posted October 28, 2011 Hey Wild Bill! That's funny. Special relativity theorizes that "light travels at a constant velocity relative to all observers". I didn't have an argument from anyone about that. So what does it mean when special relativity states that "light moves at a constant velocity relative to all observers"? It is not qualified by the statement "unless the observers are moving; in which case it's velocity would be calculated as being plus or minus the relative velocity of the observers" - even though you would intuitively think that. So adding that qualifier invalidates the statement special relativity makes that light moves at a constant velocity relative to all observers. Isn't that saying that the velocity of an observer relative to light must be zero, and the velocity of all observers relative to light must be zero? That makes sense but we are talking about relativity theory here. Observers would have to be measuring light realtive to other things and the statment is that "light travels at constant speed relative to all observers" not relative to other things. Light travels at about 300,000 KMS per second. The speed at which we travel is practically negligible, so this is why light travels the same speed for all observers. We are moving much much much slower. Quote
kimmy Posted October 28, 2011 Report Posted October 28, 2011 Dunno how you had the patience for that kimmy, I just gave up a few posts ago As Bill suggested, it's almost turning into a Betsy situation, where people stop replying and one party thinks "a ha! I'm asking questions they can't answer!" when the truth is that everybody else has decided he's beyond hope. This is becoming as frustrating as teaching my cat to type, but I hate giving up because I hate leaving him with the impression that he's debunked all of modern physics by asking really dumb questions. Light travels at about 300,000 KMS per second. The speed at which we travel is practically negligible, so this is why light travels the same speed for all observers. We are moving much much much slower. No, Gost, that's not correct. See my previous post. -k Quote (╯°□°)╯︵ ┻━┻ Friendly forum facilitator! ┬──┬◡ﾉ(° -°ﾉ)
Pliny Posted October 28, 2011 Author Report Posted October 28, 2011 No, Pliny... If I'm driving my spaceship at a speed of c/2 and there is an observer directly in front of me... the light from my headlights is approaching him at c and I am approaching him at c/2. From my point of view, the light from my headlights is also moving at the speed of light, and the observer is coming towards me at .5c. Does "from your point of view" mean the same as "relative to you"? If so then I exactly agree. I am saying, "relative" to you in your speeding spaceship, light is traveling at the speed of light. And "relative" to the observer in front of you light is traveling at the speed of light. The measurement of the speed of light is made "relative to each of the observers" not from one of the observers. You might intuitively think "she's moving at .5c and from her point of view light is moving at c so from the point of view of somebody watching, the net effect should be .5c + c = 1.5c". But you'd be mistaken, because you'd be mixing information from 2 different frames of reference. -k Exactly. So now how is what you just said different from what I have been saying? That should be easy to figure out. Quote I want to be in the class that ensures the classless society remains classless.
Pliny Posted October 29, 2011 Author Report Posted October 29, 2011 (edited) If you lean a stick against a wall, the stick is applying force to the wall. Possibly for hours, days, or even many many years. Does that mean the stick is generating infinite energy? No, Pliny, it does not. And as usual the problem here is that you just don't understand what you're talking about. You're expending energy by pressing against the wall-- contracting your muscles uses chemical energy, and generates heat. But you're not generating energy any more than the stick leaning against the wall is generating energy. Why would I think the stick is generating infinite energy in such case? The force of gravity is the only thing in play here keeping things in an equilibrium. Now if the stick were off the ground, just sort of up against the wall, seemingly defying gravity, I would wonder how that could be. If there were no mass holding it up on the wall there would have to be some force holding it up. And holding the ball at constant height is no different from a table holding a ball at constant height. Is the table burning energy? If a ball sits on a table for 100 years, does that mean that the table has generated an incalculable amount of energy during that time? No. All you are doing in this instance is inserting a mass so energy does not need to be expended. If I hold my arms out in front of me it takes energy for me to hold them there. If I put a table underneath them they are at rest and I no longer need to expend any energy holding them up. Nope. yep nope yep If you say so. If you put a brick between two magnets to keep them apart, is the brick generating energy? Nope. Right. A mass is keeping them apart. The same as a table keeps things from falling on the floor. There is no energy necessary to hold them up in that case and in your case there is no energy necessary to keep the magnets apart. Your muscles are burning chemical energy while you're holding the magnets in place, but that energy isn't being added to the system of magnets. It's being lost as heat. It's not being added to the system of the magnets. -k So all my muscles are doing are burning chemical energy and producing heat? There is no work being done. Really? With one hand on each magnet, the magnets when brought into proximity to each other will pull my hands together. Is there any energy used to do that? Usually my muscles have to burn some chemicals and produce some heat to bring my hands together. Edited October 29, 2011 by Pliny Quote I want to be in the class that ensures the classless society remains classless.
kimmy Posted October 29, 2011 Report Posted October 29, 2011 (edited) Why would I think the stick is generating infinite energy in such case? The force of gravity is the only thing in play here keeping things in an equilibrium. Now if the stick were off the ground, just sort of up against the wall, seemingly defying gravity, I would wonder how that could be. If there were no mass holding it up on the wall there would have to be some force holding it up. A mass is not holding the stick up. The normal force exerted by the ground on the stick is holding it up. It's not mass that opposes the force of gravity. It's another force. If an object is stationary, it's because all the forces acting on that object balance. In the case of a stick leaning against the wall, it is normal force balancing gravity. In the case of a magnet on a fridge, the force opposing gravity is static friction. All you are doing in this instance is inserting a mass so energy does not need to be expended. I'm inserting something that applies normal force. As far as the ball is concerned, there's no difference whether it's being held up by a table or by your hand, so why would you think energy is being generated in one scenario but not the other? The only difference between the table and your hand is that your hand will only provide normal force to hold the ball up until your muscles run out of chemical energy. If you say so. I do. You can take my word for it, or you can study why for yourself. I can't be bothered to explain concepts that are covered in basic high school physics. Right. A mass is keeping them apart. The same as a table keeps things from falling on the floor. There is no energy necessary to hold them up in that case and in your case there is no energy necessary to keep the magnets apart. yep So all my muscles are doing are burning chemical energy and producing heat? There is no work being done. Really? yep With one hand on each magnet, the magnets when brought into proximity to each other will pull my hands together. Is there any energy used to do that? Usually my muscles have to burn some chemicals and produce some heat to bring my hands together. When the magnets are in static position, they have zero kinetic energy and they have potential energy defined as (their distance from each other) times (attractive force between them). Let go of the magnets, and the potential energy converts to kinetic energy. They get closer together so they have less potential energy but they are moving faster so they have more kinetic energy. At the moment they crash together, they have zero potential energy and the kinetic energy at the moment of impact is equal to the potential energy they had when you were holding them apart. After the moment of impact, the potential energy is zero, the kinetic energy is zero, and all of that energy has been converted to sound and vibration and heat. If you're still holding on to the magnets but relax your arms so that the magnets are slowed, then it's the same except that some of the potential energy of the magnets is not converted to kinetic energy and is instead absorb by the muscles in your arms-- lost as heat-- and the collision between the magnets has less energy. So now how is what you just said different from what I have been saying? That should be easy to figure out. I'm having a really hard time figuring out what you're saying, except that as far as I can tell you think that since both observers see the speed of light to be the same, you can conclude that both observers must be stationary relative to each other. Which indicates that you've completely missed the point. -k Edited October 29, 2011 by kimmy Quote (╯°□°)╯︵ ┻━┻ Friendly forum facilitator! ┬──┬◡ﾉ(° -°ﾉ)
Pliny Posted October 31, 2011 Author Report Posted October 31, 2011 (edited) A mass is not holding the stick up. The normal force exerted by the ground on the stick is holding it up. It's not mass that opposes the force of gravity. It's another force. If an object is stationary, it's because all the forces acting on that object balance. A state of gravitational equilbrium is always trying to be maintained. In the case of a stick leaning against the wall, it is normal force balancing gravity. Yes. If the stick were off the ground, as I said, without visible means of support, then it would be out of equilibrium, a state that is not possible. In the case of a magnet on a fridge, the force opposing gravity is static friction. Static friction as a description of a magnet opposing gravity is easily dismissed when you consider a magnet will hang from a horizontal ferrous material. As far as the ball is concerned, there's no difference whether it's being held up by a table or by your hand, so why would you think energy is being generated in one scenario but not the other? The only difference between the table and your hand is that your hand will only provide normal force to hold the ball up until your muscles run out of chemical energy. My muscles, in holding the ball up, are expending energy then which will eventually deplete. Right? I generate the energy to hold it up. That's why I think energy is being generated in one scenario but not the other. Although nothing is moving when I am holding the ball up out of gravitational equilibrium, energy is still being expended to do so and you seem to agree. I'm having a really hard time figuring out what you're saying, except that as far as I can tell you think that since both observers see the speed of light to be the same, you can conclude that both observers must be stationary relative to each other. Which indicates that you've completely missed the point. -k I think if you look, I never said that the observers are stationary relative to each other. I said that they are each stationary relative to the speed of light which I don't believe is any different than what you are saying or what special relativity suggests. Gotta go. Edited October 31, 2011 by Pliny Quote I want to be in the class that ensures the classless society remains classless.
kimmy Posted November 4, 2011 Report Posted November 4, 2011 A state of gravitational equilbrium is always trying to be maintained. I'm not sure what you're trying to say, but whatever it is, the way you're saying it isn't accurate. Yes. If the stick were off the ground, as I said, without visible means of support, then it would be out of equilibrium, a state that is not possible. States where things are not in equilibrium are entirely possible. Any situation where something is accelerating is an example. F=ma ... if it were impossible for a system to be out of equilibrium, then F would always equal zero and nothing would ever accelerate. I think the idea you're floundering around looking for is this: a system will act to minimize potential energy and maximize kinetic energy. (that statement is my own "original research." I think it's essentially a restatement of the 2nd law of thermodynamics in a way that's easier for Kimmy to keep a handle on it.) Static friction as a description of a magnet opposing gravity is easily dismissed when you consider a magnet will hang from a horizontal ferrous material. Your grasp of the concepts we're discussing is easily dismissed when you consider the colossal stupidity of that statement. Of course when you rotate the system 90 degrees the forces acting on the magnet are different. If the magnet is hanging from the ceiling instead of from your fridge door, the magnetic force and gravity are in equilibrium and there's still no work being done. My muscles, in holding the ball up, are expending energy then which will eventually deplete. Right? I generate the energy to hold it up. That's why I think energy is being generated in one scenario but not the other. Although nothing is moving when I am holding the ball up out of gravitational equilibrium, energy is still being expended to do so and you seem to agree. Ok, so you understand that your table is not expending energy to hold a mass against gravity, so you apparently at least understand that holding a mass stationary against the force of gravity does not, in itself generate energy. And you understand that your arm muscles have to spend energy to remain rigid while the table does not. So I guess the missing piece of the puzzle for you is comprehending that a magnet is like a table, not like your arm. Let me help you with that. The magnet is like the table, not like your arm. The table does not spend any energy to generate the Normal Force that is opposing gravity. The magnet hanging from the ceiling does not spend any energy to generate normal force. Your muscles need to spend energy to remain contracted. So with that out of the way, let's get back to the point. You said you had all these problems because there were "anomalies" like infinite sources of energy. But it turns out that what you think is an infinite source of energy is actually just another example of your inept grasp of the subject matter. Has it occurred to you that maybe you're just not the right guy to revolutionize modern physics? I think if you look, I never said that the observers are stationary relative to each other. I said that they are each stationary relative to the speed of light which I don't believe is any different than what you are saying or what special relativity suggests. So where do we get to the "anomaly" you wanted to talk about? I can't even accuse you of trying to move the goalposts... you can't even find the goalposts anymore. -k Quote (╯°□°)╯︵ ┻━┻ Friendly forum facilitator! ┬──┬◡ﾉ(° -°ﾉ)
Pliny Posted November 6, 2011 Author Report Posted November 6, 2011 I'm not sure what you're trying to say This is true. Quote I want to be in the class that ensures the classless society remains classless.
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.