Question by Andrew Daw
Is the biggest myth of all in physics the assumption that the known forces are the only the causes that can only be described from their effects and that act universally upon matter and energy? An initial hypothesis can reason that, while the forces act so as to attract or repel between the subatomic components of atoms and molecules and external forces act upon them, a further cause would need to act constantly just so as to conserve or maintain their form and subatomic organisation for this to persist despite the action of the forces.
The organisation conserved would include that indicated in quantum mechanics by the Schrödinger equation and the Pauli exclusion principle, which describe quantum wave and spin behaviour as organisation that is required of the subatomic components of matter to account for the visible and chemical properties of the various elements and compounds. So that these wave and spin properties in particular would be produced and conserved by the cause. And this could also be true of the wave properties of the photons of light and other energy that matter radiates.
While the only universal causes that science generally recognises at present are a few push or pull causes called forces, could the universe evolve into the galaxies of stars and planetary systems, and atoms molecules and living organisms including trees and human beings given only the action of such causes? Would there not need to act a further cause or causes of a different kind to explain how the universe has evolved into and remains in this particular form? And would this not also be a cause that acts universally with what have been called non-local effects as indicated especially by experiments that have measured long distance correlations between entangled photons and nuclear components?
Reply
Nobody actually questions that in atomic physics certain causes appear to act which can not be described by the known fundamental forces. This is not only manifest in the Pauli exclusion principle but already in the existence of discontinuous energy levels i.e. the existence of atomic spectral lines in the first place. However, one has to see that these features only appear in connection with the fundamental electrostatic (Coulomb) force. In fact, the Coulomb potential explicitly enters into the Schrödinger equation which, in combination with the Pauli exclusion principle, is supposed to describe the additional quantum 'cause'. It is therefore not at all conclusive that these principles should act in anything other than bound configurations of charges (i.e. protons and electrons) and their effect on radiative atomic emissions, let alone in connection with other forces like gravity. This could, like the principles of atomic physics, only be inferred from observations and experiments. It is plausible however that this is always confined to the microscopic world as otherwise one would get into conflict with the macroscopic laws of physics (after all it is hard to imagine planets in the solar system jumping from orbit to orbit).
Having said this, it is of course obvious that these microscopic causes also have a profound effect on the macroscopic world (after all everything consists of atoms). Not only would there be not any light without them, but also our solar system and presumably also life would not have formed.
With regard to non-local effects (entanglement): this is a concept which is in my opinion based on a misinterpretation of corresponding experiments, and thus there is actually no evidence for this (see my page regarding
Bell Test Experiments).
Question by Ken Landau
I stumbled upon your site while reading some of the interesting recent works of Mike Ivsin.
I'm a simple hobbyist with an appetite for 'how things work' and have been plagued by the fact that the Crookes Radiometer is such an interested device but left as a useless table toy.
I believe that Mike may be correct in saying that photons are perhaps virtual in a sense and don't exert pressure on anything. You may have already seen this article he wrote:
http://www.hyperflight.com/oh-teacher.htm#mill_reversal.
What I believe he is saying is that people like Scandurra @ MIT and others at NASA are wrong is assuming that Thermal Transpiration (or creep) has anything to do with how the device actually functions.
My question is that I do not understand how the device works. If one were to say that a temperature differential in the gas particles causes a rise or drop in pressure and is responsible for the vane movement then wouldn't it stand to reason that putting the Radiometer in a freezer would simply increase the movement of the vanes, not reverse it?
I hear what Ivsin says about gasses moving toward each other increase the pressure on the black side of the vane but wouldn't decreasing the pressure on the white side of the vane continue it's flow
in the same direction?
I know I'm missing something simple here.
Could you be so kind as to enlighten me?
Reply
If you look at the corresponding Wikipedia article
http://en.wikipedia.org/wiki/Crookes_radiometer, then it should be obvious that it is well accepted nowadays that radiation pressure is not the reason why the vanes of the light mill rotate. Radiation pressure should actually make it rotate in the opposite sense than it actually does. What's more, for very low gas pressures, the rotation does in fact stop altogether. This shows clearly that indeed movement of the air is responsible for the effect. The article gives quite a good explanation how the different behaviour in certain cases does arise.
There is actually a different device called the Nichols radiometer (see
http://en.wikipedia.org/wiki/Nichols_radiometer which is actually supposed to demonstrate 'radiation pressure', but even this has to be considered at best as an indirect effect of radiation (e.g. because electrons are released by the light from the metallic side) but not as a proof that light possesses a momentum (which is an incorrect assumption both classically and quantum mechanically as explained on my home page entry regarding
Radiation Pressure and my pages regarding the
Wave and Particle Theory of Light applied to the Photoelectric Effect and
Energy and Momentum Conservation Laws in Physics (from which it is obvious that the concept of a 'momentum' (as well as 'energy') can only be applied in classical mechanics but not to light)).
Ken Landau (2)
Yes, I've been to these wikipedia pages in the past and am starting to understand more about the different here between 'gas pressure' caused by the radiation and the concept of 'radiation pressure' as you call it.
I've been discussing both the radiometer and the concept of the Solar Sail with Mike Ivsin and I'm not certain I agree with his theory that the solar sail won't work. (Yes, the vanes in a complete vacuum do not function but the sail will be propelled into the solar wind (a particle field) so it seems theoretically possible to propel the sail though I'm not a believer that keeping it on course is possible).
I did find an interesting technology called the 'optical tweezer' which may be of interest.
Apparently physicists use the end of a laser beam to create a magnetic force-field around an object allowing them to pull nano-particles with the end of the light beam.
I inquired about this and for particles that are either reflective or opaque and too absorbent they change the beam shape so it is not gaussian but rather donut shaped trapping the object in the free space in the middle and basically pushing the object rather than pulling it.
It is my personal believe that light is actually just a magnetic field that is acting upon unstable particles causing them to vibrate (both light itself and electricity are physical manifestations of the magnetic field- then again, I'm no physicist so I could easily be wrong) . All in all, I believe that this tweezer concept should in fact work in a vacuum as well. I have inquired about this and am still awaiting an answer.
Reply (2)
Yes, a solar sail would work because of the solar wind (i.e. a particle stream) but not as a consequence of radiation pressure. As mentioned above already, light could only lead to an apparent 'radiation pressure' due to particles released from the surface by it (as the particles will go away from the surface i.e. opposite to the direction of propagation of the light, momentum conservation would then obviously result in a force in the direction of propagation of light).
The 'optical tweezer' does not really indicate radiation pressure either. Again, if you go to the corresponding Wikipedia page
http://en.wikipedia.org/wiki/Optical_tweezers (or alternatively see
this link) then you find there basically two explanations for it: the 'Ray Optics Approach' given there argues that an asymmetry in refraction together with Newton's laws would result in the 'trapping force'. Now this is really a paradoxical and indeed flawed approach because, as is known from basic school physics, the phenomenon of the refraction of light is not consistent with Newton's laws, but can only only be explained by a wave model.
On the other hand, the 'Electric Dipole' (Rayleigh Scattering) theory results in a force which points in the direction of
increasing intensity, which is exactly opposite to what radiation pressure would do. Of course, the explanation acknowledges that this 'gradient force' is different from the 'radiation pressure' force, but the point is that the latter is only postulated as an ad-hoc concept here, but not strictly derived in a theoretical way. In fact, as I have mentioned elsewhere (see the links at the bottom of my first reply to you above), the corresponding theory for this is fundamentally flawed. Again, an
apparent radiation pressure force might well exist due to gas dynamical processes (e.g. temperature gradients) caused by the interaction of the light with the corresponding matter. In any case however, the 'optical trapping' (i.e. the gradient force) has nothing to do with 'radiation pressure' (whatever its physical explanation might be), but is a completely separate effect which even opposes the latter (as is in fact indicated in these articles).
Question by Craig Gordon
I just don't get that two-slit experiment. If particles act like particles or waves, why doesn't the single electron also spread out like a water wave and go through both holes.
Reply
This is indeed what is claimed to happen. It is postulated that an electron has both a particle and wave nature, and the latter would allow the electron to go through both holes (thus creating an interference pattern). However, it should be obvious that the particle and wave concepts are not only inconsistent with each other, but even complimentary. A particle consists basically of a localized mass, but a wave is either only a form of disturbance of an aggregate of particles (e.g. sound waves, water waves)(in which case it isn't even a physical entity as such), or, in the case of electromagnetic waves, it has indeed no particle properties like mass at all (as shown on my page
Wave and Particle Theory of Light applied to the Photoelectric Effect the particle view of light is indeed in all respects inconsistent with experiments). So it is logically inconceivable that a physical entity should have both a wave and particle property, or that it is able to switch between both properties.
I would therefore speculate that the observed interference pattern is actually not due to the electrons but due to light that is being created together with the electrons.
Craig Gordon (2)
Thanks for the response, but I still don’t get it. Why can’t a particle simply be a wave OR a particle? One or the other. It’s a wave until observation or interaction collapses it into a particle. That doesn't seem like a big deal. Certainly more plausible than all those "probability waves" I read about in Schrodinger’s Cat.
Reply (2)
What kind of wave should that be then? Certainly not an electromagnetic wave, as these don't collapse into particles on interaction with an atomic system but are either scattered or absorbed. This would leave then, as indicated above already, only the possibility of an aggregate of particles upon which a wave-like disturbance is imposed. But the wave features in that case are only possible because of the interaction of many particles. One can't have a sound- or water wave (and resulting interference effects) with just one particle. Quantum Mechanics interprets wave functions actually to the effect that these give the probability to find the particle in a particular place. But that doesn't change anything about the fact that we are dealing with a particle (which thus can not be in two places at the same time and go through both slits simultaneously).
Craig Gordon (3)
OK - aggregates of particles - it's starting to make sense. So while I'm on a roll - could I just ask you one other troubling question. Every explanation I've read for the Uncertainty Principle simply tells me you cannot precisely measure both the position and momentum of a particle at the same time. I understand why, but I cannot see why the problem isn't just experimental. Are there deeper implications?
Reply (3)
The 'uncertainty principle' is directly associated with the assumed wave nature. Strictly speaking it just means that the frequency spectrum of a wave gets wider as the wave gets shorter (this is a general mathematical property of wave-like phenomena). The interpretation as an 'uncertainty' only arises if you try to apply this principle to particles as well, i.e. if you consider a particle simultaneously as a wave, which however, as indicated above, is a logically flawed concept (many physicists don't see this logical flaw, and thus mistakenly assume there must a deeper implication, when in fact they should be looking for alternative explanations of their experiments).