Romun Nose

Fundamentals of Physics 5a)

 Falsification of Kinetic Theory

Diffusion

The transport phenomena of the admixture of two different gases does not proceed as the theory predicts. This observation is confirmed in practice by the mixing of gases for commercial use and an example is the mixture of nitrogen and helium, which is used to test high pressure piping and equipment for leaks, as it escapes through the smallest of apertures and simple equipment is available to detect the gas.

However Helium, as a rare gas, is in short supply and is very expensive, and a mixture of 5% helium and 95% nitrogen serves the purpose, and companies producing medical and industrial gases are able to supply this mixture.

But simply introducing both gases into a storage cylinder, in any order, does not achieve a homogeneous mixture suitable for practical use (i.e. with the helium atoms evenly distributed within the more numerous nitrogen atoms) unless it is left for a week or more.

A quicker method of mixing is achieved by placing such a cylinder horizontally on rollers and rotating (or ‘rumbling’) it for some time (a few hours), which process creates a frictional effect between the internal walls of the rotating cylinder and the gases in contact with it.

If the principles of the kinetic atomic theory of gases are applied to the example of static mixing, we see that, according to the theory, the average velocity of nitrogen molecules in air is around 500 metres per second and that of helium atoms is 1300 metres per second. The relative mass of nitrogen is around 14, and that of helium 4, and a typical industrial gas cylinder is around 1.5 metres high and 200 mm in diameter. If introduced after the nitrogen, the lighter helium content would be positioned in the cylinder at the top, and occupy 75mm of the internal height, while the nitrogen the remaining 1425mm.

The diagram above depicts the nitrogen molecules and the helium atoms at the separation point and the numbers conform to Avogadro’s Law.

If uninhibited by collisions, at these velocities it would be possible for the slower nitrogen molecules that are in the vicinity of the helium atoms at the top of the cylinder to travel to the top of the cylinder and back 3,300 times in one second, 200,000 times in one minute. Extending the time to one hour would enable each nitrogen molecule to travel this distance 12 million times, a total distance of 600 kilometres.

With respect to each of the helium atoms, in one second they could each travel in the other direction to the bottom of the cylinder and back around 400 times, 24,000 times in a minute. In one hour 1,500,000 times and traveling a total distance of over 2,800 kilometres.

But of course collisions of any single atom with others are frequent and such an atom would not move linearly, but in a completely random manner.

This is an unusually frank comment from a Russian textbook:- (1)

“Since this transport is ensured by motion of the molecules, and the velocities of the molecules are high, diffusion should seem to occur rapidly with the concentrations leveling out almost instantaneously. Experiments show, however, that at atmospheric pressure diffusion is a very slow process, and mixing in the absence of motion of the gas as a whole may last several days.” (My emphases)

In an attempt to explain this problem the proponents of Kinetic Theory suggest that while the molecules in the above example move chaotically at high velocity, somehow collisions with the molecules of the other gas mean they always end up in the area from which they started in the first place, somehow, in this particular instance, showing both chaotic and ordered characteristic’s at the same time. In other words suggesting that any collisions that they endure with molecules of the other gas must result in their returning to the area in which they originated.

But this is a direct contradiction of the principle that the collisions are completely random or chaotic, and instead is saying that these interactions are, by some inexplicable means, regulated or controlled.

Given the postulated random, kinetic movement, together with the large volumes of empty space separating molecules and atoms and their high velocities, the fact that mixing, in commercial and experimental practice, is very slow, is direct and incontrovertible proof that this theory is invalid.

(1) Molecular Physics, Kirkoin and Kirkoin, Mir Publishers, Moscow

Fundamentals of Physics 5b)

Falsification of Kinetic Theory

Phase Changes

The Ideal (Perfect) Gas Laws are another example and are an imperfect model of the reactions of gases to changes in pressure and temperature, and even then in a limited range of conditions. Even with numerous subsequent modifications and adjustments they still fail to produce a model which can be relied on today.

For example a textbook states that ‘ The ideal-gas equation is not valid at high pressures’ and ‘the ideal gas equation is valid for all gases at sufficiently low densities and sufficiently high temperatures’.

A clear example is that these laws completely fail to predict the behaviour of gases during the change of state from gas to liquid. An example is Carbon Dioxide at the point of liquidisation. Another textbook quote ‘for carbon dioxide at 60 ATM all similarity to perfect gas behaviour is lost’.

Let us look at this particular change of state more closely. According to Kinetic Theory the progression from gas to liquid should follow the progression as shown in the graph below for a ‘Perfect Gas’ and this is valid initially. Which means that in Kinetic Theory terms the molecules, being confined into less and less ‘space’ due to the increase in applied pressure, collide more and more often with the walls and each other thus generating an increasing resistance to the applied pressure.

According to Kinetic Theory atoms in a gas at Standard Temperature and Pressure are positioned in relation to each other at 10 molecular diameters and in a liquid at less than one molecular diameter apart.

The progression in the graph above shows that at a point where the molecules are on average about 4 diameters apart there is suddenly no additional resistance to the applied pressure and the molecules essentially move to 1 diameter apart and the gas liquefies.

Current teaching of Kinetic Theory principles attempts to explain this anomaly by saying that at Standard Temperature and Pressure separations there is no attraction between the molecules of a gas and that as the separation reduces progressively they begin to attract and the attraction increases strongly at around 4 diameters and then, in the liquid state at 1 diameter, the force between molecules then reverses and becomes strongly repulsive.

This explanation is illogical. How can there, at one point in the progression, be no attraction, then attraction increases and then decreases to a point where there is neither attraction or repulsion, then finally strong repulsion develops?

What are these attractive and repulsive forces and what is causing them to vary in an irregular fashion? How do they act through and in a vacuum?

There is no rational explanation for these changes from attraction to repulsion.

This pattern follows the whole development of Kinetic Theory from Clerk Maxwell’s Laws to the present day, in that where natural phenomena or experimental results have not conformed to the theory then ad hoc ‘adjustments’ have been made one after the other in order to try and tailor the theory to suit the observed phenomena. This leaves us today with a theory which is so convoluted and ‘adjusted’ so that even where it is capable of practical application is extremely complicated and cumbersome. It needs to be reiterated that it is of course a ‘theory’ which means that there is no experimental evidence which unequivocally proves that molecules are moving a high velocities in a vacuum in any gas. Any contrived experiment that has been carried out to prove this theory have been on the basis of assumptions whereas the examples above are naturally occurring phenomena.

Richard Feynman states in The Feynman Lectures in Physics 5, Kinetic Theory :-

“It is obvious that this is a difficult subject, and we emphasize at the beginning that it is in fact an extremely difficult subject, and that we have to deal with it differently than we have dealt with the other subjects so far. In the case of mechanics and in the case of light, we were able to begin with a precise statement of some laws, like Newton’s laws, or the formula for the field produced by an accelerating charge, from which a whole host of phenomena could be essentially understood, and which would produce a basis for our understanding of mechanics and of light from that time on. – but we do not learn different physics, we only learn better methods of mathematical analysis to deal with the situation.

We cannot use this approach effectively in studying the properties of matter. We can discuss matter only in a most elementary way; it is much too complicated a subject to analyze directly from its specific basic laws, which are none other than the laws of mechanics and electricity. But these are a bit too far away from the properties we wish to study; it takes too many steps to get from Newton’s laws to the properties of matter, and these steps are, in themselves, fairly complicated. We will now start to take some of these steps, but while many of our analyses will be quite accurate, they will eventually get less and less accurate. We will have only a rough understanding of the properties of matter.”

(Note the emphasis ‘extremely‘ is Feynman’s own, the others are mine)

Fundamentals Of Physics 5c)

 Falsification of Kinetic Theory

Convection

Kinetic Theory gives no clear explanation of heat transference between different materials, it fails to explain, for example, how this in a gas or a liquid causes a localised convective movement.

Textbooks brush over this very important heat transfer process by vague phraseology such as ‘In free convection the heating process produces a temperature and density gradient in the fluid and fluid motion is induced by the action of gravity’ and ‘temperature gradients induce convection in fluids, a phenomena that involves the movement of gases or liquids’.

The example above is a hot object placed in contact with a ‘kinetic’ gas that is at a lower temperature. What occurs in practice is that where the gas meets the object convection currents are clearly observed rising close to the surface of the object.

Kinetic Theory states that ‘Molecules that move more rapidly because they are in a region of higher temperature collide with molecules in a neighbouring region, giving the adjacent molecules more kinetic energy and consequently more thermal energy’, and that ‘heat applied to a gas results in an increase in the velocity of the molecules and a corresponding increase in collisions’ and that this increase in collisions results in a greater average molecular separation.

Clearly this would mean that where this occurs there would be fewer molecules per unit space and the total mass and therefore the density of this unit volume would be reduced by comparison with adjacent cooler unit volumes of gas.

However if a gas consists of molecules moving independently of each other in a vacuum and as the mass of these molecules remains the same and further there is ‘no attraction between molecules’, then gravity can only act on individual molecules and not the gas as a whole because the theory states that the gas as a whole is 99.9% a vacuum and this component cannot be influenced by gravity. In any case the theory also suggests that as far as individual atoms are concerned “gravity can be ignored”.

If we put this into a different perspective, this is like saying that if a number of ball bearings are suspended on wires (as in the diagram below) with a separation between them of say 20mm, and beside this suspend a similar number at separations of 40mm, then the second group would collectively have a lesser gravitational attraction to the centre of the Earth than the first group. This of course is absurd.

It follows therefore that an individual molecule in a larger volume of space has the same gravitational attraction as another molecule of the same mass in a smaller volume of space.

But Kinetic Theory is suggesting that a single molecule in a larger area of ‘space’ moving at greater velocity has a lower gravitational attraction to the earth than a slower one of the same mass in a smaller area of ‘space’. However it is the ‘space’ that has expanded and the ‘space’ cannot be affected by gravity as it is devoid of matter.

Or to put it in another way if the mass of the molecule remains the same, the gravitational effect in a vacuum would be unchanged, and it is quite clear that this kinetic process, in itself, would not result in these observed convection currents.

The only way this could occur in such circumstances is for there to be some instantaneously acting force of attraction acting between these atoms, but as the theory states that there is ‘no attraction between molecules’ the natural phenomenon of convection cannot be described by the kinetic atomic theory of gases.