Taking a Fresh Look at the Physics of Radiometers.
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From: NoEinstein on 1 Jun 2010 11:02 On May 31, 8:57 pm, "Tim BandTech.com" <tttppp...(a)yahoo.com> wrote: > Dear Tim: Where have you been?! Your logical mind, justifies cloning you... or putting you out-to-stud! Thanks for giving me a hint of how the Nichols Radiometer works. If you will make a concise top post(s) regarding science questions that relate to light or to gravity, I will be most happy to reply. But know this: I am a generalist, not a specialist. Don't try to make me into a mathematician. Those aren't generalists, nor scientists! > > On May 30, 2:58 pm, Sam Wormley <sworml...(a)gmail.com> wrote: > > > On 5/30/10 9:31 AM, NoEinstein wrote: > > > > Photons have ZERO mass, and exert zero force upon > > > âstrikingâ a reflecting surface. > > >   Photons have zero REST mass, but have momentum of > > >     p = hν/c = h/λ > > >   A perfect reflector's momentum would increase by > > >     2p = 2h/λ > > >   for every photon. Ever heard of a solar sail? > > I've recently done some research on the radiometer, and this math > analysis is definitely not what makes it tick. The sun is putting out > 1300 watts per square meter. If all of this energy goes into > mechanical energy then we'd be making turbines rather than PV cells. > > There is a 'radiation pressure' claim of one third the energy density > (loose language) supposedly from Maxwell. I haven't found that > computation yet. > > The Nichols radiometer is a torsion balance, whereas Crook's spins > freely. Somehow Nichols claims to have provided one that works in > vacuum, and yet the argument should pass freely onto the Crook's > version. How much friction can there be in a well made pin bearing > versus a quartz fiber? The Nichol's data is weird near perfect vacuum. > An inversion takes place that he just graphs and doesn't care to > explaim. He claims that the atmospheric effects can be cancelled as > shown by the zeros in his graphs. Well, at these zeros there will be > no effect. I find the Nichols claims unconvincing. > > In terms of the atmospheric effects a thermal differential causing > fluid flow at the edges is supposedly the cause, discovered by > Reynolds. I've not seen any analysis in terms of Bernoulli effect, but > if the air is rising at the black surface then the velocity of the gas > is greater there. This is the simplest explanation, but there are so > many explanations with very little proof. > > I'm pretty sure the radiation pressure argument is false. Photons are > more like AC sources than DC sources. If the pressure is alternating > then to claim a propulsive acceleration is a misnomer. It would be > like putting a ping pong ball in front of a speaker, blasting out 100 > watts and expecting the ping pong ball to accelerate away from the > speaker. > > It's interesting how easy it is to become opinionated on this topic. > Without gravity the effects of the atmosphere with temperature > difference would be diminished so it would be neat to see this > experiment done in outer space, and at various atmospheric pressures. > > I was researching this in a recent thread >   http://groups.google.com/group/sci.math/browse_frm/thread/4835ecd7ca6... > There are some links in there, starting with >   http://math.ucr.edu/home/baez/physics/General/LightMill/light-mill.html > > The most blatant farce is in terms of conservation of energy. The > claim is that the light hitting a reflective surface will provide > twice the momentum; one kick when the light hits it and one kick again > from the light when it leaves. This concept offends the conservation > of energy. 1300 watts in with 1300 watts out leaves no acceleration > whatsoever for the perfect reflector. Consider taking a full length > mirror out into the sun and being boled over by three horsepower of > push. This area is loaded with misnomers and is a great subject for > it. > >  - Tim
From: NoEinstein on 1 Jun 2010 11:13 On Jun 1, 12:24 am, Timo Nieminen <t...(a)physics.uq.edu.au> wrote: > Dear Timo: If the (supposed) pressure exerted by 'solar radiation' is correct, then, such can be used to determine what percentage of the ether is still trapped between the photons. The ether that's present between the mass-less photons is what 'moves' the vanes of a Nichols Interferometer Fresh radiationâas from a highly heated Cavendish ballâ will be carrying outward a higher percentage of ether. The latter could affect the relative gravity strength. This will be an interesting area for study, by others, down the road. â NE â > > On Mon, 31 May 2010, Tim BandTech.com wrote: > > On May 30, 2:58 pm, Sam Wormley <sworml...(a)gmail.com> wrote: > > > On 5/30/10 9:31 AM, NoEinstein wrote: > > > > > Photons have ZERO mass, and exert zero force upon > > > > âstrikingâ a reflecting surface. > > > >   Photons have zero REST mass, but have momentum of > > > >     p = hν/c = h/λ > > > >   A perfect reflector's momentum would increase by > > > >     2p = 2h/λ > > > >   for every photon. Ever heard of a solar sail? > > > I've recently done some research on the radiometer, and this math > > analysis is definitely not what makes it tick. The sun is putting out > > 1300 watts per square meter. If all of this energy goes into > > mechanical energy then we'd be making turbines rather than PV cells. > > Apart from some very early claims about the Crookes radiometer (such as > by Crookes), shown to be wrong a few years later, and their modern > repetition, who claims that radiation pressure makes the radiometer tick? > > 1300W per square metre means 9 micronewtons per square meter, on a > perfect reflector. That it would take a square kilometer to be able to use > solar radiation pressure to produce the same force as the weight of 1kg > pretty much says why we don't do this. > > (A little more at the bottom of post.) > > > There is a 'radiation pressure' claim of one third the energy density > > (loose language) supposedly from Maxwell. I haven't found that > > computation yet. > > Try Maxwell's Treatise. Art 792, pp 391-392 in 1st edition. > > > I'm pretty sure the radiation pressure argument is false. Photons are > > more like AC sources than DC sources. If the pressure is alternating > > then to claim a propulsive acceleration is a misnomer. It would be > > like putting a ping pong ball in front of a speaker, blasting out 100 > > watts and expecting the ping pong ball to accelerate away from the > > speaker. > > Why not? Just don't expect a large acceleration; I don't think that 100W > would be enough to levitate against gravity. > > It's been done, google or youtube for "acoustic levitation". > > > The most blatant farce is in terms of conservation of energy. The > > claim is that the light hitting a reflective surface will provide > > twice the momentum; one kick when the light hits it and one kick again > > from the light when it leaves. This concept offends the conservation > > of energy. 1300 watts in with 1300 watts out leaves no acceleration > > whatsoever for the perfect reflector. > > If the reflector is moving, there will be a Doppler shift, and energy in > will be different from energy out. If the reflector is stationary, then > you could have, e.g., 1300W in and 1300W out. But no work would be done. > > Even better, if the light is slowing the reflector down, the reflected > light has more energy than the incident light. Just as one would expect > from conservation of energy. > > Back to the idea of using solar radiation to produce mechanical energy. If > you can move the 1 square kilometer reflector at 1km/s downwards, then > you'd get a power of 9kW, from a total of 1.9GW input solar power. This is > very poor efficiency compared to even poor solar cells. > > -- > Timo- Hide quoted text - > > - Show quoted text -
From: Timo Nieminen on 1 Jun 2010 17:02 On Jun 1, 10:22 pm, "Tim BandTech.com" <tttppp...(a)yahoo.com> wrote: > On Jun 1, 12:24 am, Timo Nieminen <t...(a)physics.uq.edu.au> wrote: > > > 1300W per square metre means 9 micronewtons per square meter, on a > > perfect reflector. That it would take a square kilometer to be able to use > > solar radiation pressure to produce the same force as the weight of 1kg > > pretty much says why we don't do this. > > Yes, well, I'd like to understand how even this slight figure comes > about. It is easy to falsify the e=hv momentum claim (which is a big > enough statement) but even this slender acceleration is questionable > by the argument on conservation of energy. Here is another derivation: Consider a steady beam of monchromatic light incident on a stationary reflector. Each optical cycle has energy E (i.e., the total energy of a length of the beam equal to 1 wavelength). The incident power P is thus P = Ef, where f is the optical frequency.The output power is the same, since the reflected beam is identical, except for the reversed direction. Since the reflector is stationary, no work is being done on it. Now change to a coordinate system where the reflector is in motion, at a speed v away from the source of the incident beam. (For simplicity, assume v << c.) The incident beam is now blue-shifted, and the frequency of the incident beam in this coordinate system is now f(1+v/ c), and the power is P_in = Ef(1+v/c). Similarly, the reflected beam now has power P_out = Ef(1-v/c). Since energy is conserved, the difference in power must be the rate of doing work on the reflector. P_reflector = P_in - P_out = 2Efv/c = 2vP/c. Since P_reflector = F_reflector * v, we have: F_reflector = 2P/c, which is the radiation pressure due to complete reflection at normal incidence. This is the simplest derivation of radiation pressure I know of. -- Timo
From: Tim BandTech.com on 2 Jun 2010 10:46 On Jun 1, 9:40 am, Timo Nieminen <t...(a)physics.uq.edu.au> wrote: > On Jun 1, 10:22 pm, "Tim BandTech.com" <tttppp...(a)yahoo.com> wrote: > > > > > On Jun 1, 12:24 am, Timo Nieminen <t...(a)physics.uq.edu.au> wrote: > > > On Mon, 31 May 2010, Tim BandTech.com wrote: > > > > On May 30, 2:58 pm, Sam Wormley <sworml...(a)gmail.com> wrote: > > > > > On 5/30/10 9:31 AM, NoEinstein wrote: > > > > > > Photons have ZERO mass, and exert zero force upon > > > > > > âstrikingâ a reflecting surface. > > > > > Photons have zero REST mass, but have momentum of > > > > > p = hν/c = h/λ > > > > > A perfect reflector's momentum would increase by > > > > > 2p = 2h/λ > > > > > for every photon. Ever heard of a solar sail? > > > > I've recently done some research on the radiometer, and this math > > > > analysis is definitely not what makes it tick. The sun is putting out > > > > 1300 watts per square meter. If all of this energy goes into > > > > mechanical energy then we'd be making turbines rather than PV cells.. > > > Apart from some very early claims about the Crookes radiometer (such as > > > by Crookes), shown to be wrong a few years later, and their modern > > > repetition, who claims that radiation pressure makes the radiometer tick? > > > The Nichols radiometer is claimed by some to work in a vacuum, > > including Nichols himself. > > Nichols and Hull (and Lebedev very shortly before them) were operating > at the limits of what they could detect or measure, with the best > vacuums they could manage affordably. That their results aren't > terribly good shouldn't be a surprise. But it's been done again, and > it doesn't have to be done in vacuum. We discussed some of these > experiments inhttp://arxiv.org/abs/0710.0461- the work by R. V. > Jones was excellent, his 1954 measurements might well be the best pre- > laser measurements of optical radiation pressure. > > So, whatever your doubts about Nichols' experiment, it's been repeated > and amply confirmed many times (and at least some of these were by > people who didn't Nichols' results were really good enough). These > days, it's almost trivial. I've reviewed your paper "Momentum of an electromagnetic wave in dielectric media". I wonder to what degree the name 'energy-momentum tensor' is a strict meaning? If we accept that the electric field is sinusoidal and so has zeros then all of the expressions that you consider contain instaneous zeros within their representation. This suggests that conservation of 'energy-momentum' does not exist, but then, these are not claims on just momentum are they? As you say we should consider a monochromatic and coherent source to simplify matters. This is fairly analogous to Maxwell plane wave isn't it? With the experiment of Ashkin and Dziedzic did they ever bother to drive the beam up out of the water into the air and observe a reversal of their effect? Did they ever bother to consider that the thermal heating of the water could be providing their effect? In the experiment of Jones and Richard you say "Jones sought to verify the prediction that when a mirror was immersed in a dielectric medium, the radiation pressure exerted on the mirror would be proportional to the refractive index of the medium." yet this goes in exact contradiction to the claimed Reynolds effect, where immersion in a fluid is subject again to thermodynamic effects. As you say above here to just relax, because these experiments have been done again, and that the weakness of Nichols work does not exist in perpetutity, well, I believe that I have presented evidence here that these experimenters are the ones who relaxed on top of the work of Nichols. Lastly, I would argue from a very simplistic perspective that if conservation of energy and momentum is upheld that these figures in vacuum should match these figures in solid media. Otherwise where did the energy or momentum go? I admit that my own belief is that the momentum is actually zero in terms of a steady unidirectional push on a plate of material, but in that light does propagate in a given direction we must admit the energy itself is directed, but when for instance we absorb all of that energy as in a black ideal absorber, that it has nothing to do with mechanical momentum. The claims of propulsion doubling from a perfect reflector only help to boost my position. I guess to pose the simplest question that I can on this is to ask whether the energy of a photon e = h f is the entire energy of the photon? What have you concluded about Wormley's claim on the momentum figure here? Isn't this figure the classical blackbody figure of momentum? How did the discrepancy then to a very slight momentum figure arise and how do we split that smaller energy off of this photon energy without corrupting physics? > > (I will be brief for the rest, since it is late. Perhaps I can give > more detail or refs later.) > > > > 1300W per square metre means 9 micronewtons per square meter, on a > > > perfect reflector. That it would take a square kilometer to be able to use > > > solar radiation pressure to produce the same force as the weight of 1kg > > > pretty much says why we don't do this. > > > Yes, well, I'd like to understand how even this slight figure comes > > about. It is easy to falsify the e=hv momentum claim (which is a big > > enough statement) but even this slender acceleration is questionable > > by the argument on conservation of energy. > > This is just the momentum of a photon p=h/lambda claim. But it isn't a > quantum result; quantum mechanics just inherits this from the > classical theory. The standard result in the classical theory is that > the momentum flux of a parallel beam of power P is P/c (for light in > free space or some medium with refractive index close enough to 1). > For light in some other medium, such as water, momentum flux = nP/c. > > You can obtain this result via at least 3 different routes: > > (a) the Lorentz force, (i) by directly calculating the force for a > specific case, or (ii) by obtaining the momentum flux of an > elecromagnetic wave along the lines of the derivation of Poynting's > theorem. > > (b) the Lagrangian formulation of EM theory + Noether's theorem. > > (c) the thermodynamics of moving energy around without moving mass > around. > > Jackson's book, Classical electrodynamics, does (a)(ii) and (b). (c) > goes back to N. A. Umov, 1874 (I haven't seen this last in English). > > > Why oh why would we rely upon a volume figure to assess the force on a > > plate? The figuring does not extend generally either. For instance, > > staying with Watts and Joules and seconds what if we consider a one > > second interval of the solar power? Now rather than a 1mx1mx1m box we > > have a box extending 3e8 meters toward the sun, and now the > > computation gets trickier, for the assumption on this 1kJ box of > > energy now has to worry about the proximity to the sun. > > We don't have to rely on a volume to find the force on a plate. But > the density and flux of a quantity are related by the speed of > transport of the quantity, so once you know the density, you know the > flux. > > > I am not familiar with modern physics using the electokinetic energy > > versus electrostatic energy. What seems most familiar is > > e = h v > > where v is proportional to the frequency of a supposed photon. You > > seem to have validated that photon momentum is not responsible for the > > radiation pressure. > > Maxwell's "electrokinetic energy" isn't modern. Maxwell can be hard to > read, since he is archaic. > > > I'm honestly not clear on whether you are in support of a mechanical > > pressure or not. This does not really matter, but because the > > ballistic theory of light and black body principles rest nearby, then > > there is some cause for interest beyond the toy light-mill's > > functionality. I believe it is accurate to translate the 1300 W/m/m of > > the sun directly into photon energy. If one photon > > e = h v > > is a bullet then how much force does it impart? Is Wormley correct? > > Then why doesn't it translate? You see, we are knocking on the back of > > the black door. > > I don't think we're anywhere mysterious here. Inertia of energy (which > means that moving energy has momentum) goes back to Umov 1874 on > thermodynamic grounds, Einstein 1905 on more general relativistic > grounds, that electromagnetic energy has inertia goes back to Poynting > and Heaviside in 1884. Given the energy of a photon as E=hf, then you > have mometum p=h/lambda, since p=E/c. > > And it all works for other kinds of waves, and angular momentum too. > > But it used to be mysterious. Back in the early 1800s, it was argued > that light was a wave phenomenon rather than a corpuscular phenomenon > since radiation pressure was not observed - how could something > massless like a wave exert a force? > > These days, with the idea that electromagnetic fields can exert > forces, and light being an electromagnetic wave, optical radiation > pressure is about as mysterious as an electric motor. Which is to say, > that it exists and works is clear, whatever fundamental mysteries of > "why" remain. I'm sorry but the effect in a perfect vacuum has not been clearly demonstrated. As you've accepted the flaws of Nichols work then the question of whether the radiation pressure is observable in vacuum still exists. The experiments that you've exposed in your paper must not be the modern experiments that you speak of. > > It's well-tested quantitatively. It isn't too hard to verify the > momentum of light to within 10% using optical tweezers (e.g., our > experiment inhttp://arxiv.org/abs/physics/0610087. Yes, we say > better than 1%, but that's with a known particle for calibration, to > find the power at the focus of our trap. Without this, we'd have a > larger error, mainly in the estimate of this power. Still, no more > than 10%.) > > > > > The most blatant farce is in terms of conservation of energy. The > > > > claim is that the light hitting a reflective surface will provide > > > > twice the momentum; one kick when the light hits it and one kick again > > > > from the light when it leaves. This concept offends the conservation > > > > of energy. 1300 watts in with 1300 watts out leaves no acceleration > > > > whatsoever for the perfect reflector. > > > > If the reflector is moving, there will be a Doppler shift, and energy in > > > will be different from energy out. If the reflector is stationary, then > > > you could have, e.g., 1300W in and 1300W out. But no work would be done. > > > Very good. We have agreement, particularly at the low velocities that > > these instruments work at. As far as we can tell there is no reliance > > upon red shifting of light, which could provide some work. > > The force doesn't depend on redshift. But it doesn't take any > expenditure of energy to produce a force - just ask a fridge magnet or > a paperweight. Having the force do work does very much depend on > redshift, since the reflector has to move for the radiation pressure > to do work on it. Awww, come on.... The claim is that the force is doing work, and the existence of any redshift in doing that work has been completely ignored in any of these theories or experiments. Without doing some work there will be no indication as of a vane which rotates on a tensioned fiber. We know we're at extremely low velocity in this experiment, so any redshift observed would be a highly impressive mechanism. I don't mean to get too ornery, but you are sweeping over these points as if there is no fundamental problem. This is somewhat the attitude of modern physics. It is true that proffessional physicists must produce work in order to be proffessional, and this I do not mean as an insult to you, but to explain the overall attitude of the community. I really appreciate your input and it is very detailed, but particularly on the claim that modern experiments have gone beyond the shadow of doubt, well, we will first need something working in vacuum which observes the supposed radiation pressure. From the theoretical side there is a reliance upon a third of the energy density for this pressure that we still have not arrived at, though you've gotten very close in Maxwell's treatise. Here is the strongest link that I have found in support of challenging the existing theory: http://www.neumann-alpha.org/lightpressure.pdf This site is a bit out there, but then, so too was Nichols. Any who will rest on top of his work, and that is how science is done, are on a shaky ladder. - Tim
From: Tim BandTech.com on 2 Jun 2010 11:33
On Jun 1, 11:02 am, NoEinstein <noeinst...(a)bellsouth.net> wrote: > On May 31, 8:57 pm, "Tim BandTech.com" <tttppp...(a)yahoo.com> wrote: > > Dear Tim: Where have you been?! Your logical mind, justifies cloning > you... or putting you out-to-stud! Thanks for giving me a hint of how > the Nichols Radiometer works. If you will make a concise top post(s) > regarding science questions that relate to light or to gravity, I will > be most happy to reply. But know this: I am a generalist, not a > specialist. Don't try to make me into a mathematician. Those aren't > generalists, nor scientists! > Geeze, what a compliment. So rare on usenet. I share somwhat your concept of a generalist and have posed that question in the past of where these generalists are? It is pretty easy to grow skeptical of the course of science given the system's structure of censors on a quantity of journals whose access is protected by a price tag that few can afford, and whose accumulation is overwhelming. Still, there is a tension between freedom to construct and correctness. I will argue for the freedom to construct, and, to accept all that is printed in journals is perfect is a farcical stance. It is more apt to state that what is printed in journals fits the censors' agendas. Well, hooray for arxiv.org! What about right here on usenet? Why shouldn't scientists be free to disagree with each other in the open? What better means of falsification could there be? In terms of seeking the truth I suspect that this medium could be more effective than the journal system, which is a protected form. Why shouldn't the conversations be open? Probably because in a climate of falsification everyone will appear to be failures. Still, shouldn't we seek out those falsifications as a means to drive toward some fundamental truth? Just imagine the level of slander that would go on with the behemoths who struggle for millions of dollars for their pet projects. We are humans practicing science as our only alternative, other than resignation to reality on her own terms. Is the over exuberance of wall street's elite possible in the scientific community? As an outsider looking in, and seeing that fundamentals do still remain to be constructed by humans, then the idea that we are overlooking something fairly simple is an affirmation of the faith of science; that answers do exist. The problems are open. Those who attempt to shut others down are practicing dead science. Falsification of one idea will lead to another idea, and that is how we work; the current position should not take the attitude that it has taken, but we are still caught nearby. The clean answers may exist, but these are not necessarily consistent with the current position. Here is an agile medium for propagation of ideas and the corrective falsifications that are needed, with no worry of a control freak censor stepping in. - Tim > > > > On May 30, 2:58 pm, Sam Wormley <sworml...(a)gmail.com> wrote: > > > > On 5/30/10 9:31 AM, NoEinstein wrote: > > > > > Photons have ZERO mass, and exert zero force upon > > > > âstrikingâ a reflecting surface. > > > > Photons have zero REST mass, but have momentum of > > > > p = hν/c = h/λ > > > > A perfect reflector's momentum would increase by > > > > 2p = 2h/λ > > > > for every photon. Ever heard of a solar sail? > > > I've recently done some research on the radiometer, and this math > > analysis is definitely not what makes it tick. The sun is putting out > > 1300 watts per square meter. If all of this energy goes into > > mechanical energy then we'd be making turbines rather than PV cells. > > > There is a 'radiation pressure' claim of one third the energy density > > (loose language) supposedly from Maxwell. I haven't found that > > computation yet. > > > The Nichols radiometer is a torsion balance, whereas Crook's spins > > freely. Somehow Nichols claims to have provided one that works in > > vacuum, and yet the argument should pass freely onto the Crook's > > version. How much friction can there be in a well made pin bearing > > versus a quartz fiber? The Nichol's data is weird near perfect vacuum. > > An inversion takes place that he just graphs and doesn't care to > > explaim. He claims that the atmospheric effects can be cancelled as > > shown by the zeros in his graphs. Well, at these zeros there will be > > no effect. I find the Nichols claims unconvincing. > > > In terms of the atmospheric effects a thermal differential causing > > fluid flow at the edges is supposedly the cause, discovered by > > Reynolds. I've not seen any analysis in terms of Bernoulli effect, but > > if the air is rising at the black surface then the velocity of the gas > > is greater there. This is the simplest explanation, but there are so > > many explanations with very little proof. > > > I'm pretty sure the radiation pressure argument is false. Photons are > > more like AC sources than DC sources. If the pressure is alternating > > then to claim a propulsive acceleration is a misnomer. It would be > > like putting a ping pong ball in front of a speaker, blasting out 100 > > watts and expecting the ping pong ball to accelerate away from the > > speaker. > > > It's interesting how easy it is to become opinionated on this topic. > > Without gravity the effects of the atmosphere with temperature > > difference would be diminished so it would be neat to see this > > experiment done in outer space, and at various atmospheric pressures. > > > I was researching this in a recent thread > > http://groups.google.com/group/sci.math/browse_frm/thread/4835ecd7ca6... > > There are some links in there, starting with > > http://math.ucr.edu/home/baez/physics/General/LightMill/light-mill.html > > > The most blatant farce is in terms of conservation of energy. The > > claim is that the light hitting a reflective surface will provide > > twice the momentum; one kick when the light hits it and one kick again > > from the light when it leaves. This concept offends the conservation > > of energy. 1300 watts in with 1300 watts out leaves no acceleration > > whatsoever for the perfect reflector. Consider taking a full length > > mirror out into the sun and being boled over by three horsepower of > > push. This area is loaded with misnomers and is a great subject for > > it. > > > - Tim |