International Journal of Theoretical and Mathematical Physics
p-ISSN: 2167-6844 e-ISSN: 2167-6852
2013; 3(2): 53-68
doi:10.5923/j.ijtmp.20130302.02
Subhendu Das
CCSI, West Hills, California, 91307, USA
Correspondence to: Subhendu Das, CCSI, West Hills, California, 91307, USA.
| Email: | ![]() |
Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved.
This is a multi-disciplinary paper. It borrows ideas from mathematics, engineering software, and digital communication engineering. Uncertainty principle is at the foundation of quantum mechanics. (A) It is well known that this principle is a consequence of Fourier transform (FT). The FT is based on infinity assumption. As infinity is not realistic and meaningful in nature, and in engineering, we show that replacing infinity by any finite value changes the lower bound of the uncertainty principle to any desired accuracy number. (B) The paper points out, that uncertainty principle violates a very fundamental and well known concept in mathematics: the infinite dimensionality property of functions over finite intervals. (C) It is important to realize that no engineering experiment can prove any theory. Engineering is created out of objects of nature. Nature does not and cannot make any assumptions. Thus all engineering experimental setups will automatically eliminate all assumptions from all theories. To establish this obvious and logical fact, we discuss many laws of nature, which modern microprocessor based engineering systems implement. Therefore it is not possible to prove uncertainty principle by any physical experiment, because the principle has many assumptions. (D) We explore several published proofs of uncertainty principle, including Heisenberg’s and Operator theoretic, and analyze the assumptions behind them to show that this theory cannot be a law of nature. The paper ignores the relativistic effects.
Keywords: Quantum Mechanics , Uncertainty Principle, Numerical Methods , Fourier Transform, Operator Theory
Cite this paper: Subhendu Das, Assumptions in Quantum Mechanics, International Journal of Theoretical and Mathematical Physics, Vol. 3 No. 2, 2013, pp. 53-68. doi: 10.5923/j.ijtmp.20130302.02.
![]() | (1) |
![]() | Figure 1. Saturation Non-Linearity |
Then
is defined by![]() | (2) |
![]() | (3) |
![]() | (4) |
![]() | (5) |
![]() | (6) |
![]() | (7) |
![]() | (8) |
functions and Schrodinger’s equation. Observe that (6-8) are equivalent statements, i.e., one can be derived from the other. Thus the form of R in (8) could have been assumed directly. In the next proof we show, that is what has been done.Normalizing gives c the value
. He claims, quite naturally that, the values of Δp and Δq are thus not independent. This is also obvious from his assumption of relating p and q via (4-5). To simplify further calculations, he introduces the following abbreviations:
Then equations (2) and (3) become![]() | (9) |
![]() | (10) |
![]() | (11) |
![]() | (12) |
may be transformed, giving
Thus he writes, by using integration by parts, and noting that S(q’) is related to probability density function vanishing at two ends:![]() | (13) |
can be proved by rearranging![]() | (14) |
Or![]() | (15) |
or
where c is an arbitrary constant. Thus Gaussian probability distribution causes the product
to assume its minimum value.In summary, Heisenberg assumed that momentum and wave functions are related by the Fourier transform pair (11) and (12). Then he defined the variances of the time and spectrum functions using (9) and (10). Then a simple algebraic manipulation proved the uncertainty relation (15). From (15) we see that uncertainty is the product of time and spectrum variances (bandwidth) of FT pair. It is clear from the above proof that there is no physical or experimental support behind the result (15), the uncertainty principle. It is a consequence of Fourier Transform which has its own assumptions as we will examine later. In particular, we will show that by removing infinity assumption we can remove the uncertainty.
Then on page 22, Ohanian8 starts with four conceivable harmonic waves
Using some selection criteria he finally decides that
from the list as the correct wave function describing a free particle. Then he finds the equation that this function must satisfy. He writes, it is easy to check that the second derivative of
with respect to x and the first derivative with respect to time t are proportional, that is, we can write
The above equation is a linear equation and therefore will be compatible with the superposition principle. Therefore any function
that can be written as a superposition of a finite or infinite number of waves of the type
will satisfy the differential equation![]() | (16) |
![]() | (17) |
is called the amplitude in momentum space. This is where Ohanian makes the same assumption as Heisenberg did. He assumes position and momentum are related by inverse FT. There is no reason to believe that nature will obey this relation. This assumption is also not based on any experimental observations. On the other hand it is quite natural that a particle can have any momentum at any position. Also note that it introduces the infinity assumption in (17). Then he finds
by substituting (17) in (16) giving
Now comparing both sides the coefficients of
we obtain the following differential equation
Which has the solution given by (18); this way Ohanian gets a general expression (18) of momentum in the time dimension.![]() | (18) |
Thus the general solution of the Schrodinger’s wave equation for a free particle can be written from (17) as
The above solution can be written in terms of the momentum
as in (19)![]() | (19) |
![]() | (20) |
Calculation of the integral using (20) gives the result
Substituting the Gaussian momentum amplitude (20) into equation (19) we find the wave function![]() | (21) |
From the last expression we see that the mean is
and we can then find that the uncertainty in x is as given by ![]() | (22) |
From (22) we see that for all other time for a given
the value for
increases because of t in (22), which then gives
We can see from this proof that the uncertainty principle can be proven without going through the higher level analysis that Heisenberg has given. Note that Heisenberg also uses the Schrodinger equation. It is clear from Ohanian’s proof also that there is no physics involved. It is all mathematical manipulation of FT theory.Summarizing, Ohanian8 assumes that momentum and wave function are related by the infinite inverse FT in (17). He then gets a general expression (18) for the time dimension of momentum by using Schrodinger’s equation. Then he assumes a Gaussian function (20) for the momentum dimension. Finally the uncertainty result is obtained as the product of the variances from (20) and (21). Thus we see that Ohanian’s proof is almost same as the Heisenberg’s proof, so far as assumptions are concerned. There is no physics involved here; it essentially tries to say that whatever happens in mathematics, will happen in nature also. The proof forgets that nature cannot make the two assumptions used in the derivations (a) infinity in FT and (b) the relation (17) that says momentum and position are related by the FT. It cannot be said that this uncertainty relation is derived from any experimental observation.On the contrary, all experimental efforts to verify the principle will inevitably fail, because we cannot setup the assumptions used in the derivation. In particular, we cannot test it for infinite time as required by the theory of Fourier Transform. The theory is valid only under infinite time assumption. As we show later, if we replace the infinity by any finite value then there will be no uncertainty. Thus finite time approximation cannot be used to test the principle. Finite time will not be an approximation, it will be a dramatic change as we have mentioned.
and
be any two complex valued functions in V, let the inner product in V be denoted by
For convenience we note the following properties of complex inner product:
Let X be a linear operator mapping V into V. Then we define the mean
and variance of
in the following way, with respect to a given normalized vector
.
We present the following lemma9, called the Schwartz inequality taken from page 14; the proof is given in a later section.Lemma Let
and
be two arbitrary vectors. Then
The proof of uncertainty principle starts with the following lemma9 on page 119.Lemma Let O1 and O2 be two Hermitian operators. Then![]() | (23) |
.Proof Let us apply the Schwartz inequality to vectors
and
. Because O1 and O2 are Hermitian, one has![]() | (24) |
One sees that
and
so that![]() | (25) |
End of proof.Let us now apply the lemma to the case where
One has
Thus one gets
From which Heisenberg’s inequality immediately follows.![]() | Figure 2. Operators cannot be cascaded |
in (24), is a violation of engineering practice. It is an assumption.Figure 2 dictates the block diagram for testing the uncertainty principle based on the operator theoretic proof. In Figure 2, the device under test (DUT) is the system which is generating the state vectors or wave functions. All operators are like experiments or like test equipments that are used to test the DUT. Operators are designed to work only on DUT. In the figure operator A is denoted by an experiment or test equipment1 that tests the output signals from DUT. Input to operator A is the wave function from the DUT and its output is a measurement function. We can see that cascading means operator B is not working on the DUT or the wave function, but on the measurement function. Measurement function is not same as the wave function. Measurement function is not generated by the DUT; it is generated by the test equipment1.The two input signals are different, they come from different environments, and they cannot be comparable. The cascading theory violates the simultaneity law. Once an operator is used on a wave function its output cannot be a wave function again. Wave function does not remain a wave function when it is processed and taken out of its environment. In the absence of the simultaneity environment, a wave function loses its characteristics. Nature is immensely complex, anything taken out of environment, behaves completely differently. Thus cascading is equivalent to the assumption of isolated environment, as in Newton’s first law, which we know cannot work.The characteristics of an object significantly change when it is taken out of its environment. When I am outside my home, I am a completely different person. Earth taken out of its orbit will not remain as earth. Same is true for the operator outputs. Thus the concept of commutation is not meaningful in engineering. Cascading operators is an assumption; it is not meaningful for engineering test of a theory. Figure 2 becomes an invalid test setup for testing uncertainty principle. Figure 2 shows that the operator theoretic proof is inconsistent with nature.The proof is also invalid for many other assumptions we have mentioned, like infinite space time assumptions. We have discussed them in other places. In this section we elaborated the cascading requirement only, which violates the simultaneity law. Thus the operator theory cannot be tested, and according to our definition of invalidity, the operator theory cannot work.![]() | (26) |
is the angle between the two vectors;
means the magnitude or the length of the vector. Since cosθ is always less than or equal to 1, we can write the Schwartz inequality as in![]() | (27) |
Then we can see the Schwartz inequality of real numbers as
It is clear that the above is valid for n-dimensional vectors. In case of n-dimensional vectors, cosθ can be defined as![]() | (28) |
Clearly the integral Schwartz inequality will still remain valid for infinite limits for the integrals in the last expression under the assumption of appropriate integrability conditions.Theorem: Let u and v be arbitrary members of an inner product space V. Then the Schwartz inequality is given by
Proof: If v=0 then clearly theorem is satisfied. Assume then that
. For an arbitrary scalar
,
Or
From which the assertion follows. Note that
is same as cos
as defined by (28). A pictorial view of (26) will show why the expression is correct.From figure 3 we can see the real meaning of the Schwartz inequality. Clearly the product of the magnitude or the length of the two vectors a and b is bigger than the product of b and c. The product of b and c is
whereas the product of a and b is simply
. This is a purely mathematical property; it requires complete isolation from any other physical requirements. It is a manmade theory lives in isolation from nature. A manmade theory cannot be a law of nature. All laws of nature must be experimentally observed by using engineering experiments.![]() | Figure 3. Schwartz inequality for vectors |
and
, taken by two different operators on the same vector
are two different objects, like apples and oranges. Therefore applying dot products on them are not meaningful. As mentioned, an operator represents an experiment on objects of nature. Two operators represent two different experiments. Their use in (24) or in Figure 3 is inconsistent with engineering concepts of an experiment.To illustrate the incompatibility of the operator outputs, the following example may be better. Suppose we take a cat described by four different properties and represent it using a vector [c1, c2, c3, c4], similarly we a take a dog described by another five different properties represented by[d1, d2, d3, d4, d5]. These two vectors represent simultaneous environments of cats and dogs respectively. Let us now use an operator C that converts the cat vector in to a two dimensional vector of numbers, and similarly we take another operator D and convert the dog vector to another two dimensional vector. (Note that C and D are not entirely meaningless. We use them in our manmade society. In economics, we convert every human being to a money value.) Even though the resulting vectors are of same dimensions we cannot still take their inner products, because by the equivalence principle as described later, they are different objects. The properties of cats and dogs are embedded in the two vectors, making them in eligible for dot products. Thus the application of Swartz inequality to derive uncertainty principle is not meaningful.Algebra makes a very fundamental assumption: all variables belong to the same class, like real numbers. In nature, things are never same. We always have apples and oranges. Even two apples are different. Just like we cannot add two apples and three oranges to give five apples or five oranges, in the same way we cannot add five apples also, because all five apples are different. In reality, even algebra has very limited applications in nature. We must remain vigilant about the applications and the assumptions of mathematics.No variable in nature is isolated; they are all connected by simultaneity law with many other things in its environment. Thus each variable is unique. No two variables can be compared. The core assumption in algebra is isolation of variables, which is invalid in nature. Nature obeys the simultaneity law. We can only compare output of same operators but not two different operators. We cannot compare apples and oranges. The two functions
and
used in (24) are like apples and oranges, when
are all objects of nature. They are not merely mathematical entities.![]() | (29) |
![]() | (30) |
. Expression (30) gives the Inverse FT from the spectrum function,
, and produces the time function, x(t). In a previous section we have given two proofs that show that uncertainty principle is derived from the FT theory. In this section we analyse the FT in more details to find the root cause of this uncertainty.Observe that both integrals have infinity as limits. One way to examine this infinity requirement of FT is to visualize the example of the delta function. Its FT is 1 for all w. That means all cosine functions that create the delta function have unit amplitude and zero phase. If you draw some of these cosine functions, see Priemer11 in pages 178-179, you will find that the functions are adding up to create the pulse and becoming zero at all other places. This example shows that all cosine functions must be defined over all time, and the same must be true for the delta function also. That is, the delta function must exist as zero for the entire real line except the place where it is non-zero.Consider the time function shown in Figure 4 and the corresponding Fourier transformed spectrum function shown in Figure 5. The graph in Figure 5 was obtained using expression (29). Both functions must be defined and must exist for the entire x-axis as required by the FT theory. The width of the distribution in spectrum Δw is 4π/ΔT and the width Δt = ΔT of the distribution in time function can be regarded as uncertainties. The product of these two uncertainties show that![]() | (31) |
. Where
and
. Use the following notations to represent the t-subintervals
then define the characteristic functions:
and the simple functions:
Theorem 1
The above theorem, Das15, essentially says that the sequence of step functions, with step height defined by the sample values, converges to the original function. These samples, collected as a column vector represent the infinite dimensional vector for the function. Thus given any accuracy limit, a step function can be generated that will represent the function with that accuracy. The theorem says that this conclusion is valid for any finite interval.![]() | Figure 4. Time function |
![]() | Figure 5. Spectrum function |
![]() | (32) |
to
, because x(t) comes from (29), the FT. Replacing time t by Nyquist sampling interval we get![]() | (33) |
to
and therefore it is same for n in (33). Thus the function x(t) can be “completely specified”, as stated in the dimensionality theorem, once we get all the coefficients from (33), construct the X(w) from them using the Fourier series, and then use that known X(w) to reconstruct x(t) using (32). Observe that this process requires infinite number of samples using all values of n in (33). Thus function x(t) must be defined for all t to make the process work. A Fourier series requires infinite number of coefficients.Thus the total number of samples required to recover the signal x(t) for very large value of T is given by![]() | (34) |
![]() | Figure 6. Different spectrums for same pulse |
![]() | (35) |
![]() | (36) |
Let q1 be the precision with which the value q is known (q1 is, say the mean error of q), therefore here the wave length of the light. Let p1 be the precision with which the value of p is determinable; that is, here, the discontinuous change of p in the Compton effect. Then according to the elementary laws of the Compton effect p1 and q1 stand in relation p1 q1 ~ h.”It is not known, how much of engineering technology existed in 1927 and how much familiarity a theoretical physicist like Heisenberg had about that engineering. Clearly in modern times this will not be the design of an experiment by any stretch of mind of any system engineer. Two unknowns cannot be found out by one measurement; this will produce one equation in two unknowns. At least two equations will be necessary to solve for both p and q variables. Heisenberg seems to believe that only one measurement will give values for both p and q. This is an assumption he used unconsciously. In reality, a significantly large volume of dynamic data should be collected, for a long period, both before and after hitting the electron, all simultaneously, and then eliminate all unknowns by least square curve fitting algorithm of dynamical systems, something like Kalman Filtering. It is almost unbelievable that how much accuracy we can achieve using modern technology and with such simultaneous measurements. Simultaneity is a law of nature, more we encompass it better results we get. GPS satellites are about 20,000 km above earth. Yet we can measure distances on the surface of earth at the accuracy of sub-millimeter level, see Hughes18, in geodetic survey, by measuring the satellite distances. In one sense then we can measure a distance of 20,000 km at the accuracy of sub-millimeter. This approach uses only non-military GPS signals. So we can think, how accurate the results can be, with the exact military signals from new generation of GPS satellites and receivers. Thus at this modern time, in retrospect, it is difficult to understand why Heisenberg thought about such an experiment involving one measurement to identify two variables.