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  1. #1 The speed of light... 
    Forum Professor leohopkins's Avatar
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    If the speed of light inside a vacuum is 186,000 miles per second, then what is the speed of light inside a washing machine?


    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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    Same.


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    It depends on the make if it,s a good make it could be faster.
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    Quote Originally Posted by Ghrasp
    It depends on the make if it,s a good make it could be faster.
    That is false. Speed of light is c, regardless of medium. Perhaps you mean the apparent speed?
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    er.....

    Okay (the joke aside)....

    Speed of light is ALWAYS "C" - yes that is correct.

    However, the value of "C" changes depending on the medium which light is travelling through.

    Regards;
    Leo
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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    i think the speed of light is a constant value wherever part of universe you are in.. though im aware that light may slow down in transparent media, which im studying right now and is called the refractive index. but the fact that light slows down like mentioned in our textbook seems very vague to me.
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  8. #7  
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    Quote Originally Posted by leohopkins
    er.....

    Okay (the joke aside)....

    Speed of light is ALWAYS "C" - yes that is correct.

    However, the value of "C" changes depending on the medium which light is travelling through.

    Regards;
    Leo
    No.

    The symbol "c" is universally used in physics to represent the speed of a photon aka the speed of light in a vacuum. That speed is a fundamental constant of physics and it does not change.

    Photons always travel at c. What is perceived as the speed of light in a mediun,other than a vacuum, is the result of interactions between photoons and the atoms that comprise the medium -- basically repeated absorptions and re-emissions. But when a photon exits it travels at only one speed with respect to all inertial reference frames.
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    Zero when it hits the side of the wasing machine.
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    Zero when it hits the side of the wasing machine.
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    light travels faster between two plates spaced nanometers apart in a vacuum... (casimir effect)
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    errr....you sure? Can anyone confirm that? I thought the Casimir effect was explained differently.
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

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    light travels faster between two plates spaced nanometers apart in a vacuum... (casimir effect)
    wait a minute, this is Casimir effect? i thought Casimir effect was a phenomenon where small attractive force results from two parallel uncharged conducting plates. im not sure about the part where the lights gets faster? explanation??
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  14. #13  
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    Yes, the Casimir effect has no effect on the speed of light.
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    Quote Originally Posted by Heinsbergrelatz
    light travels faster between two plates spaced nanometers apart in a vacuum... (casimir effect)
    wait a minute, this is Casimir effect? i thought Casimir effect was a phenomenon where small attractive force results from two parallel uncharged conducting plates. im not sure about the part where the lights gets faster? explanation??
    The Casimir effect is a quantum effect, and has no effect on the speed oflight.

    The speed of a photon is always c,

    The most commonly cited Casimir effeect results in an attractive force, but there are situations that can produce a repulsive force as well.

    http://en.wikipedia.org/wiki/Casimir_effect
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    I don't see how an effect on the speed of light can be totally discounted with regard to the Casimir effect which can produce a repulsive force too which is an area of interest for those looking at levitation.

    A simple experiment to demonstrate the Casimir effect could take the form of two parallel plates each fixed to a pair of arms that can be adjusted to move the plates toward or away from each other. A stress-meter between the arms could measure any force that exists between the plates. Let us assume that the plates have a large enough surface area to cause a measurable force.

    If such a Casimir experiment were to be performed outside of a vaccuum, i.e., in the atmosphere, the situation could arise where, if the plates were close enough to each other, air molecules are forced out from between the plates such that a partial vaccuum would occur with respect to the atmosphere surrounding the experiment. Atmospheric pressure would then cause a force that presses the plates toward each other. The stress-meter would show a reading that indicates that there is an force of attraction between the plates.

    On the other hand, if air was blown accross the plane of the plates then air could be forced between the plates such that the pressure between the plates is higher than atmospheric pressure. This would cause a force that pushes the plates apart and the stress-meter would record a reading that would indicate that a force of repulsion existed between the plates.

    In both cases, atmospheric pressure explains the Casimir effect that seems to occur but it appears that the same thing happens in a vaccuum; the stress-meter records a force of attraction, or repulsion, when the plates are close together.

    Now, suppose it was the case that dynamism in sub-atomic structures was derived from the movement of un-energetic (cold) space flowing into energetic (hot) space; that the boundary between hot and cold space is what gives rise to existence as we perceive it. That is to say that every sub-atomic particle exerts a 'sucking' force that draws cold space towards it resulting in an expanding system whose components (regions of cold space surrounded by regions of hot space) are seperated by constantly flowing streams of cold space which is absorbed into the system. This process would be manifest as gravity in large masses.

    If the atoms on the internal surfaces of the two plates plates are close enough to each other then there could be a depletion of cold space between them as they compete for a source of energy. The two plates would exert a force on each other as they try to 'suck' space through each other; a force that would appear to be attractive.

    This depletion would cause the space between the plates to be stretched; a vaccuum in a vaccuum.

    Imagine that we had a fibre-optic rod that measured 186,000 miles in length and at each end we place a device that emits a pulse of light into the rod whenever it receives one. We press a button that makes one of the devices transmit a pulse of light. One second later, the second device receives the pulse and transmits another pulse back to the first device. So, the two devices flash alternately every second.

    Now, suppose we could place the rod exacly halfway between two super-massive black-holes that are quite close to each other. Assuming that our rod is resistant to the stretching that the black-holes would surely cause and so maintaining its form, how often would the lights flash? The space between the black-holes would be stretched; wouldn't light energy propogate more quickly in depleted space in the same way that ripples travel faster along the surface of water than they do over oil?

    So, if the space between the plates is depleted then light-energy could cross the gap slightly quicker than normal.

    Of course, this would depend on space itself having a property.

    Phew! That seemed like hard work. :?
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    Quote Originally Posted by himnextdoor
    I don't see how an effect on the speed of light can be totally discounted with regard to the Casimir effect which can produce a repulsive force too which is an area of interest for those looking at levitation.

    A simple experiment to demonstrate the Casimir effect could take the form of two parallel plates each fixed to a pair of arms that can be adjusted to move the plates toward or away from each other. A stress-meter between the arms could measure any force that exists between the plates. Let us assume that the plates have a large enough surface area to cause a measurable force.

    If such a Casimir experiment were to be performed outside of a vaccuum, i.e., in the atmosphere, the situation could arise where, if the plates were close enough to each other, air molecules are forced out from between the plates such that a partial vaccuum would occur with respect to the atmosphere surrounding the experiment. Atmospheric pressure would then cause a force that presses the plates toward each other. The stress-meter would show a reading that indicates that there is an force of attraction between the plates.

    On the other hand, if air was blown accross the plane of the plates then air could be forced between the plates such that the pressure between the plates is higher than atmospheric pressure. This would cause a force that pushes the plates apart and the stress-meter would record a reading that would indicate that a force of repulsion existed between the plates.

    In both cases, atmospheric pressure explains the Casimir effect that seems to occur but it appears that the same thing happens in a vaccuum; the stress-meter records a force of attraction, or repulsion, when the plates are close together.

    Now, suppose it was the case that dynamism in sub-atomic structures was derived from the movement of un-energetic (cold) space flowing into energetic (hot) space; that the boundary between hot and cold space is what gives rise to existence as we perceive it. That is to say that every sub-atomic particle exerts a 'sucking' force that draws cold space towards it resulting in an expanding system whose components (regions of cold space surrounded by regions of hot space) are seperated by constantly flowing streams of cold space which is absorbed into the system. This process would be manifest as gravity in large masses.

    If the atoms on the internal surfaces of the two plates plates are close enough to each other then there could be a depletion of cold space between them as they compete for a source of energy. The two plates would exert a force on each other as they try to 'suck' space through each other; a force that would appear to be attractive.

    This depletion would cause the space between the plates to be stretched; a vaccuum in a vaccuum.

    Imagine that we had a fibre-optic rod that measured 186,000 miles in length and at each end we place a device that emits a pulse of light into the rod whenever it receives one. We press a button that makes one of the devices transmit a pulse of light. One second later, the second device receives the pulse and transmits another pulse back to the first device. So, the two devices flash alternately every second.

    Now, suppose we could place the rod exacly halfway between two super-massive black-holes that are quite close to each other. Assuming that our rod is resistant to the stretching that the black-holes would surely cause and so maintaining its form, how often would the lights flash? The space between the black-holes would be stretched; wouldn't light energy propogate more quickly in depleted space in the same way that ripples travel faster along the surface of water than they do over oil?

    So, if the space between the plates is depleted then light-energy could cross the gap slightly quicker than normal.

    Of course, this would depend on space itself having a property.

    Phew! That seemed like hard work. :?
    gibberish
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  18. #17  
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    Quote Originally Posted by himnextdoor
    I don't see how an effect on the speed of light can be totally discounted with regard to the Casimir effect which can produce a repulsive force too which is an area of interest for those looking at levitation.
    snip
    Please restrict such idle speculation to the New ideas and Hypotheses forum.
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    Quote Originally Posted by Somanayr
    light travels faster between two plates spaced nanometers apart in a vacuum... (casimir effect)
    NO light cannot travel with more speed than c in any medium.
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    I guess there is no point in investigating the possibilities of faster than light travel then.

    "It's impossible, they cried,
    But I did it when I tried."

    (Someone who did something first)
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    Such possibilities are being investigated at places like NASA. An important thing to note though is that the people investigating these things thoroughly understand the rules they're attempting to circumvent so they can see what lines of inquiry are worth pursuing and they can know when their idea has hit a dead end.
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    Quote Originally Posted by MagiMaster
    Such possibilities are being investigated at places like NASA. An important thing to note though is that the people investigating these things thoroughly understand the rules they're attempting to circumvent so they can see what lines of inquiry are worth pursuing and they can know when their idea has hit a dead end.
    You wiildly overestimate NASA.

    There is no, repeat no, evidence that faster than light travel is possible. As far as we know with the current knowledge of basic physics it is not.
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    Well, I didn't say that they're making any real progress, just that there are people at NASA considering it.
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    Quote Originally Posted by MagiMaster
    Well, I didn't say that they're making any real progress, just that there are people at NASA considering it.
    I can probably find people at NASA considering any hair-brained scheme that you care to name.

    Your tax dollars at work.
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by MagiMaster
    Well, I didn't say that they're making any real progress, just that there are people at NASA considering it.
    I can probably find people at NASA considering any hair-brained scheme that you care to name.

    Your tax dollars at work.
    Ha ha. Amen to that.

    Can I offer this;

    You shine a light into a super-massive black-hole. Can there ever be a point where the space in front of the light can accellerate away from the light? Would the light just stop if the space in front of it just disappeared?
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    You're going to have to define what you mean by space accelerating and space disappearing, because as far as I know, those phrases don't mean much.
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    Quote Originally Posted by himnextdoor
    Quote Originally Posted by DrRocket
    Quote Originally Posted by MagiMaster
    Well, I didn't say that they're making any real progress, just that there are people at NASA considering it.
    I can probably find people at NASA considering any hair-brained scheme that you care to name.

    Your tax dollars at work.
    Ha ha. Amen to that.

    Can I offer this;

    You shine a light into a super-massive black-hole. Can there ever be a point where the space in front of the light can accellerate away from the light? Would the light just stop if the space in front of it just disappeared?
    No.

    And space does not accelerate, let alone accelerate away from anything. With respect to what would space accelerate ?
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    Quote Originally Posted by MagiMaster
    You're going to have to define what you mean by space accelerating and space disappearing, because as far as I know, those phrases don't mean much.
    The other way round might be easier.

    You have a light source, a laser, that emits a certain number of photons in a narrow beam at a constant rate and let's say we can monitor the average density of photons over time.

    Then the laser is allowed to fall into a really big black-hole.

    As the torch accelerates toward the black-hole, the photon density will decrease and the ones that can be detected will have lost energy; they will have a longer wavelength.

    At this point, the situation is that all the light emitted from the laser is escaping from the black-hole but if you add up the total energy of the photons you detect, you get a result which is lower than the amount of energy that was emitted. (Red-shifted=lower energy, yes?)

    Where is the missing energy?

    The torch is falling quickly now and we are counting less and less photons that are carrying less and less energy. We receive one more photon then, nothiing.

    Where is the next photon? Is it suspended just inside the event horizon with a wavelength longer than a week moving at zero miles per second? It must be. A photon at rest. (And they said it couldn't be done.)

    And if the photon stopped, it must first have slowed down. This suggests that the next photon has even less energy; will subsequent photons change direction and start falling into the blackhole? The photons outside the black-hole would be moving away from the photons in the hole at speeds greater than the speed of light.

    Whereas, if the torch were facing into the hole and we were looking at the light from the middle of the black-hole, we would observe a blue-shift in the light indicating an increase in energy. (I wonder how short a wavelength can be.)

    The thing is, how does the law of conservation of momentum hold out here? More energy means more momentum doesn't it? More momentum means either an increase in mass or an increase in velocity.

    But if it has mass then it can't travel at the speed of light. (Does Einstein still apply?)

    Perhaps the speed of light CAN be exceeded.
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    Quote Originally Posted by DrRocket
    No.

    And space does not accelerate, let alone accelerate away from anything. With respect to what would space accelerate ?
    Any other point in space.
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    Quote Originally Posted by himnextdoor
    Quote Originally Posted by DrRocket
    No.

    And space does not accelerate, let alone accelerate away from anything. With respect to what would space accelerate ?
    Any other point in space.
    That would be a metric expansion of space and not an acceleration of space. The first makes sense and is well known. The second is utter nonsense.
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  31. #30  
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    Quote Originally Posted by himnextdoor
    Quote Originally Posted by MagiMaster
    You're going to have to define what you mean by space accelerating and space disappearing, because as far as I know, those phrases don't mean much.
    The other way round might be easier.

    You have a light source, a laser, that emits a certain number of photons in a narrow beam at a constant rate and let's say we can monitor the average density of photons over time.

    Then the laser is allowed to fall into a really big black-hole.

    As the torch accelerates toward the black-hole, the photon density will decrease and the ones that can be detected will have lost energy; they will have a longer wavelength.

    At this point, the situation is that all the light emitted from the laser is escaping from the black-hole but if you add up the total energy of the photons you detect, you get a result which is lower than the amount of energy that was emitted. (Red-shifted=lower energy, yes?)

    Where is the missing energy?

    The torch is falling quickly now and we are counting less and less photons that are carrying less and less energy. We receive one more photon then, nothiing.

    Where is the next photon? Is it suspended just inside the event horizon with a wavelength longer than a week moving at zero miles per second? It must be. A photon at rest. (And they said it couldn't be done.)

    And if the photon stopped, it must first have slowed down. This suggests that the next photon has even less energy; will subsequent photons change direction and start falling into the blackhole? The photons outside the black-hole would be moving away from the photons in the hole at speeds greater than the speed of light.

    Whereas, if the torch were facing into the hole and we were looking at the light from the middle of the black-hole, we would observe a blue-shift in the light indicating an increase in energy. (I wonder how short a wavelength can be.)

    The thing is, how does the law of conservation of momentum hold out here? More energy means more momentum doesn't it? More momentum means either an increase in mass or an increase in velocity.

    But if it has mass then it can't travel at the speed of light. (Does Einstein still apply?)

    Perhaps the speed of light CAN be exceeded.
    The total mass/energy of the laser and its photons will be constant from its frame of reference. Answering the question from a different frame of reference is beyond my current level of understanding, but it's not a simple question. IIRC, momentum is frame dependent, but each photon's momentum is taken out of the laser's.

    Once the laser falls into the event horizon, the photons do not simply stop. They can't leave the event horizon, but they can move around within it. As to what they're doing exactly, no one knows yet. It's called a horizon for a reason.
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  32. #31  
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    Quote Originally Posted by himnextdoor
    Quote Originally Posted by MagiMaster
    You're going to have to define what you mean by space accelerating and space disappearing, because as far as I know, those phrases don't mean much.
    The other way round might be easier.

    You have a light source, a laser, that emits a certain number of photons in a narrow beam at a constant rate and let's say we can monitor the average density of photons over time.

    Then the laser is allowed to fall into a really big black-hole.
    This much makes sense

    Quote Originally Posted by himnextdoor
    As the torch accelerates toward the black-hole, the photon density will decrease and the ones that can be detected will have lost energy; they will have a longer wavelength.

    At this point, the situation is that all the light emitted from the laser is escaping from the black-hole but if you add up the total energy of the photons you detect, you get a result which is lower than the amount of energy that was emitted. (Red-shifted=lower energy, yes?)

    Where is the missing energy?

    The torch is falling quickly now and we are counting less and less photons that are carrying less and less energy. We receive one more photon then, nothiing.

    Where is the next photon? Is it suspended just inside the event horizon with a wavelength longer than a week moving at zero miles per second? It must be. A photon at rest. (And they said it couldn't be done.)

    And if the photon stopped, it must first have slowed down. This suggests that the next photon has even less energy; will subsequent photons change direction and start falling into the blackhole? The photons outside the black-hole would be moving away from the photons in the hole at speeds greater than the speed of light.

    Whereas, if the torch were facing into the hole and we were looking at the light from the middle of the black-hole, we would observe a blue-shift in the light indicating an increase in energy. (I wonder how short a wavelength can be.)

    The thing is, how does the law of conservation of momentum hold out here? More energy means more momentum doesn't it? More momentum means either an increase in mass or an increase in velocity.

    But if it has mass then it can't travel at the speed of light. (Does Einstein still apply?)

    Perhaps the speed of light CAN be exceeded.
    This is complete nonsense. It doesn't describe anything.

    It is not right. It is not even wrong.
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    The point is that the energy perceived to have been lost outside the black-hole may be acconted for by the energy percieved to have been gained inside the black hole.

    Gravity around a black hole 'seems' to strip photons of energy. Maybe all gravity does it to some extent.

    But what is a photon with no energy?
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by himnextdoor
    Any other point in space.
    That would be a metric expansion of space and not an acceleration of space. The first makes sense and is well known. The second is utter nonsense.
    And would metric expansion be effected in the viscinity of a black-hole?
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    himnextdoor - My sense is that you are thinking about blackholes as if they are these strange, magical, mystical entities in the universe with all sorts of special features and powers. This IMO is causing your imagination to run around without boundary.

    However, as a point of fact, blackholes are really no different than other stars in the universe... Stars like our sun. They are just really dense objects, sometimes quite small and other times quite massive, and they effect things around them like any celestial body would. Try to recall that our sun has gravity which keeps the earth in orbit around it EXACTLY the same as a blackhole has gravity which keeps bodies in orbit around that, until their orbit eventually degrades and they fall inward (their horizontal motion no longer overcomes the inward motion).

    Try to keep that in mind. Blackholes are not magical catch-all mystery machines... Not everything about them, anyway. They are just like stars that are really really really dense, but like stars all the same.


    Now, of course I simplify, and things change somewhat once you cross the event horizon and approach the center, but overall, they're just like all of the other stars in our sky. I thought saying this might be helpful to you somehow. I'm not sure. Enjoy.
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  36. #35  
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    Quote Originally Posted by himnextdoor

    And would metric expansion be effected in the viscinity of a black-hole?
    Certainly. The metric expansion of space is strongly affected by gravity. That is why we see distant galaxies receding rapidly but do not see any such behavioir with regard to galaxies in our local group, which is gravitationally bound.

    But that has nothing to do with your earlier post.

    It also requires a fairly sophisticated look at a decomposition of space-time which is not germane to your earlier post either.
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    @DrRocket, when a body's mass increases, it pulls the space-time fabric around it inward, stretching it. This 'stress' is is transmitted to the rest of space as a wave.

    In this sense, space can be said to move.

    At the moment that the mass is added, local space-time, which was in equillibrium, increases its rate of expansion. Some part of the space-time vector will show an acceleration of some process.

    c is the speed of light in a vaccuum. If the quality of the vaccuum can change then why can't the speed of light?

    @inow, You make imagination without boundary sound like a bad thing; unbounded imagination gave us Eistein's universe. Some of the greatest achievements began with 'What if? Every now and then, somebody does something that has never been done before and a great many of those things simply 'Couldn't be done'.

    I love talking about this stuff and I love to hear about it but there seems to be less 'discussing and debating' here than there is 'rebuffing and berating'.

    Well, I don't mind playground bullies or elitists; they are as fleas on someone else's dog to me.

    I like you though.

    And, if there is no majority objection, I'd like to continue to contribute. There are people who can benefit from my input.
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  38. #37  
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    No worries, nextdoor. I was just implying that some of the thoughts you've shared are not entirely grounded in fact or reality. This is not necessarily a bad thing, no, but unbounded can unfortunately sometimes lead to more confusion than understanding... That's all.

    Either way, keep asking questions. That's great. I would just encourage you to slow down a bit and better understand the answers provided prior to asking lots more and losing track of yourself and the ideas about which you are so profoundly curious.

    Take care. 8)
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    Sometimes, when I'm watching the kettle boil and the steam is pouring out of the spout making a cloud, I imagine that I'm shrinking really quick and observing the cloud from the inside. I imagine that if I'm small enough, I would observe a swirling cluster of steam that resembles a galaxy, in a sky filled with such galaxies.

    Even smaller and I can see an arrangement that puts me in mind of the solar system; and a planet.

    On the planet, there is a microcosmic Edwin Hubble and he is looking through a telescope at the heavens and he has deduced that, because of the apparent motion of all the galaxies he can see, the Universe originated from a point about five inches above the kettle, three minutes ago and from out of nothing.

    What science could that microcosmic Edwin Hubble perform that could lead him to the kettle?

    To me, Black-Holes represent the future of all matter and the future of science.
    To me, Black-holes are the kettle.

    @ inow, Word. 8)
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  40. #39  
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    Quote Originally Posted by himnextdoor
    I love talking about this stuff and I love to hear about it but there seems to be less 'discussing and debating' here than there is 'rebuffing and berating'.

    Well, I don't mind playground bullies or elitists; they are as fleas on someone else's dog to me.
    I'd just like to point out that you do not seem to be open to discussion and debate. You're not just ansking questions, you're making statements, and when people point out that those statements are incorrect, you don't seem to be listening. You should defininitely keep asking questions, but you need to back up, ask simpler questions and understand the answers before moving on.
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  41. #40  
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    Quote Originally Posted by himnextdoor
    @DrRocket, when a body's mass increases, it pulls the space-time fabric around it inward, stretching it. This 'stress' is is transmitted to the rest of space as a wave.

    In this sense, space can be said to move.

    At the moment that the mass is added, local space-time, which was in equillibrium, increases its rate of expansion. Some part of the space-time vector will show an acceleration of some process.

    c is the speed of light in a vaccuum. If the quality of the vaccuum can change then why can't the speed of light?

    @inow, You make imagination without boundary sound like a bad thing; unbounded imagination gave us Eistein's universe. Some of the greatest achievements began with 'What if? Every now and then, somebody does something that has never been done before and a great many of those things simply 'Couldn't be done'.

    I love talking about this stuff and I love to hear about it but there seems to be less 'discussing and debating' here than there is 'rebuffing and berating'.

    Well, I don't mind playground bullies or elitists; they are as fleas on someone else's dog to me.

    I like you though.

    And, if there is no majority objection, I'd like to continue to contribute. There are people who can benefit from my input.
    Nonsense.

    Moreover your last sentence shows conclusively that you do not recognize the potential damage to young lurkers that can come from the total lack of scientific content of your posts.

    There is not one whit of scientific substance in your posts. It is so far off the mark that there is no way to correct it.

    One can only discuss and debate when there is some hint of logic or truth to serve as common ground.
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  42. #41  
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    Quote Originally Posted by DrRocket
    Nonsense.

    Moreover your last sentence shows conclusively that you do not recognize the potential damage to young lurkers that can come from the total lack of scientific content of your posts.
    And you've demonstrated that you don't read.

    Nearly all of my posts regarding photons have proceeded with 'Is it fair to say that', 'Would you accept that', 'Is it the case that' and any model that I have tried to utilise as an aid to understanding has been declared. With a few 'What ifs' for good measure I have made no claim to specific expertise except, for example the transformer question, where I 'Know My Stuff'.

    Do you refute what I contributed there; you seem to? If you do, YOU'RE WRONG.

    I come here to help and learn; why are you here? What do you contribute?

    I guess the question of whether you are a teacher or not is settled.
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  43. #42  
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    Quote Originally Posted by himnextdoor
    Quote Originally Posted by DrRocket
    Nonsense.

    Moreover your last sentence shows conclusively that you do not recognize the potential damage to young lurkers that can come from the total lack of scientific content of your posts.
    And you've demonstrated that you don't read.

    Nearly all of my posts regarding photons have proceeded with 'Is it fair to say that', 'Would you accept that', 'Is it the case that' and any model that I have tried to utilise as an aid to understanding has been declared. With a few 'What ifs' for good measure I have made no claim to specific expertise except, for example the transformer question, where I 'Know My Stuff'.

    Do you refute what I contributed there; you seem to? If you do, YOU'RE WRONG.

    I come here to help and learn; why are you here? What do you contribute?

    I guess the question of whether you are a teacher or not is settled.
    Sonny, it is you who don't read.

    Take a look at the QUOTES of your posts to which I responded. They do not meet your description here.

    If you want to learn, ask a reasonable quesiton. If you want to be criticized, continue to make ridiculous assertions.
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  44. #43  
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    http://www.newscientist.com/article/...ly-exist-.html

    http://www.causeeffect.org/articles/phopart1.html

    Patently, the the jury is still out.

    Feymann had to have positrons coming back to the future to make his QED theory work; how is that more plausible than, "In the beginning there was the word and the word was God"?

    And let's face it, 'The God Hypothesis' is the most successful theory of all time.

    You're entitled to your religious beliefs and so is everyone else.

    Positrons from the future. PAH!
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  45. #44  
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    The only way one theory can be said to be more successful than another is if both make testable predictions and one's predictions come true while the other's doesn't. "The God Hypothesis" (assuming you're talking about religion now) makes no testable predictions.

    As far as the one electron universe hypothesis, that's just an entertaining idea that has nothing to do with QED.
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  46. #45  
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    Quote Originally Posted by himnextdoor
    http://www.newscientist.com/article/mg14319392.200-science-do-photons-really-exist-.html

    http://www.causeeffect.org/articles/phopart1.html

    Patently, the the jury is still out.

    Feymann had to have positrons coming back to the future to make his QED theory work; how is that more plausible than, "In the beginning there was the word and the word was God"?

    And let's face it, 'The God Hypothesis' is the most successful theory of all time.

    You're entitled to your religious beliefs and so is everyone else.

    Positrons from the future. PAH!
    No, patently you don't know what in the hell you are talking about, as usual.

    Neither of your "sources" are relaiable, and in fact both are junk.

    Go read a good physics book and stop making ridiculous statements. There are several good books out there. I have already suggested to you the best introductory text that there is -- The Feynman Lectures on Physics. Once you have learned that material then you might be ready for more sophisticated physics. Quantum electrodynamics would definitely be "more sophisticated" physics. You are clearly not ready for that.

    Feynman's idea involving a symmetry between electrons moving forward in time and positrons moving backwards came up when he was a graduate student. His advisor, John Archibald Wheeler, had the task of extending the idea to be compatible with special relativity. Einstein, predicted that Wheeler's job would never be accomplished, and he was right. The idea is classical in nature.

    Quite contrary to your latest ridiculous assertion, the symmetry in question is in no way necessary for quantum electrodynamics. QED is one of the most successful theories in the history of physics. The jury has long ago rendered its verdict in this matter.
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  47. #46  
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    A free electron moving through space shielded from electromagnetic energy does not emit photons.

    Is that incorrect?
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  48. #47  
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    Quote Originally Posted by himnextdoor
    A free electron moving through space shielded from electromagnetic energy does not emit photons.

    Is that incorrect?
    There is literally nowhere that is completely shielded from the electromagnetic force.
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    Granted.

    But an electron carries energy in a magnetic field. In a space (theoretically) free of EMR, an electron would still generate a magnetic field and the electron would not be emitting photons.
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  50. #49  
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    If the electron is generating a magnetic field, the region is not free of EMR.
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  51. #50  
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    Quote Originally Posted by MagiMaster
    If the electron is generating a magnetic field, the region is not free of EMR.
    Then the electron must be emitting photons that occupy every point of the field which is much larger than the electron in that it occupies more space. What compels the photon to stay near the electron?
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  52. #51  
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    For one thing, they're virtual photons. That means that the exist only transiently. In a weird way, they pop into existence, and then fade back out before anything can notice them, but they still have an effect of the universe.
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  53. #52  
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    Quote Originally Posted by MagiMaster
    For one thing, they're virtual photons. That means that the exist only transiently. In a weird way, they pop into existence, and then fade back out before anything can notice them, but they still have an effect of the universe.
    Wierd is right. :?

    How do they 'know' that the electron is there?

    I mean, the probability of a virtual photon seems to be high when there is an electron around.
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  54. #53  
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    Now you're getting outside of my area of confidence, so we'll have to wait for someone else to answer that question.
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  55. #54  
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    Quote Originally Posted by himnextdoor
    Granted.

    But an electron carries energy in a magnetic field. In a space (theoretically) free of EMR, an electron would still generate a magnetic field and the electron would not be emitting photons.
    No.

    You are trying to impose a fairly classical picture on quantum field theory and it does not work that way.

    An electron is surrounded by a cloud of virtual particles.

    There is no space that is theoretically free of photons. The quantum vacuum is not "nothing".

    You might take a look at Frank Wilczek's book "The Incredible Lightness of Being". Despite the funny title it is a pretty good popularization of some aspects of quantum field theory by someone who really knows the subject well.
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  56. #55  
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by himnextdoor
    Granted.

    But an electron carries energy in a magnetic field. In a space (theoretically) free of EMR, an electron would still generate a magnetic field and the electron would not be emitting photons.
    No.

    You are trying to impose a fairly classical picture on quantum field theory and it does not work that way.

    An electron is surrounded by a cloud of virtual particles.

    There is no space that is theoretically free of photons. The quantum vacuum is not "nothing".

    You might take a look at Frank Wilczek's book "The Incredible Lightness of Being". Despite the funny title it is a pretty good popularization of some aspects of quantum field theory by someone who really knows the subject well.
    So in a way, every point in space is capable of being a photon and an electron is occupied by space?
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    This might seem silly but, if space is expanding, is photon production increasing?

    A cubic foot of space can 'hold' a certain number of photons today, will it be able to hold more tomorrow?

    Do photons expand with the universe?
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  58. #57  
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    Quote Originally Posted by himnextdoor

    So in a way, every point in space is capable of being a photon and an electron is occupied by space?
    no
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  59. #58  
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    Quote Originally Posted by himnextdoor
    This might seem silly but, if space is expanding, is photon production increasing?

    A cubic foot of space can 'hold' a certain number of photons today, will it be able to hold more tomorrow?

    Do photons expand with the universe?
    Photons are not produced by space.

    There is no such thing as the volume of a photon, so there is no such thing as the photon capacity of a cubic foot of space.

    Photons don't expand. They have no volume in the first place.

    Elementary particles are not little marbles.

    So far as is known mass and energy are the same thing. So far as is known the mass/energy content of the universe is a constant and has bee the same ever since the big bang.
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