|1 Nicolaas Vroom||Wikipedia and Einsteins Thought Experiments||Wednesday 29 January 2020|
|2 carleto4...@gmail.com||Re :Wikipedia and Einsteins Thought Experiments||Wednesday 29 January 2020|
|3 Nicolaas Vroom||Re :Wikipedia and Einsteins Thought Experiments||Wednesday 5 February 2020|
Wikipedia and Einsteins Thought Experiments.
2 posts by 2 authors
https://groups.google.com/forum/?fromgroups=#!topic/sci.physics.relativity/k8EsGxBMNao keywords = Thought experiments, Einstein
The question raised in this posting is to what extent thought experiments can be used as a basis to do science. IMO less as you read in the literature.
1) A typical case is the train experiment in par 2.3 In a broader context, this experiment is about two trains of equal length. One at 'rest' and one moving. In the text we can read: "At the precise moment that M and M' coincide in their positions, lightning strikes point A and B equidistant from M and M'." When that is the case and if we assume that in the frame of M (at rest) the speed of light is the same in all directions than it is a crystal that M will observe the two flashes simultaneous and M' not. Both will agree.
But it is not that simple. But suppose M' claims: The speed of light is the same in all directions in a frame (of Observer O) but neither you nor I are at rest in that frame and neither you or I will observe the two flashes simultaneously. Is this possible?
IMO it is and the only way to find out is by means of a real experiment.
2) In the train experiment in par 2.3, no physical length contraction is considered. If that is the case the sketch as part of par 2.3 is still valid, because it shows the situation at the moment of IMPACT. The situation will become different after the experiments when the difference between the two points of contact are compared. Assuming M' is the moving train then the difference between the two points of contacts will be larger on train M'then on train M.
IMO, again, the only way to find out is by means of a real experiment.
3) In par 4.4 Einstein's Lightbox is discussed.
1. After emitting a photon, the loss of weight causes the box to rise in the gravitational field.
Maybe that is the case, but the only way to find out is in a real experiment. But in a real experiment, you have to be very careful. The picture (as part of the text) is not clear, what is actual weighed because if the enclosure is weighed and the photon hits the enclosure than such a photon does not count. The same with the shutter and the clock. What also is tricky that also in step 1 (like in step 2) there can be bouncing
What IMO only makes sense: is to try a qualitative experiment and to detect that there is a mass loss when there is a photon emission and forget the steps 2-6.
4) In par 4.5 EPR Paradox is discussed. This paragraph involves quantum entanglement and action at a distance.
To establish quantum entanglement only real experiments can be used. In a process in which quantum entanglement has involved, atom A emits 2 particles, for example, two photons. Of these two photons, for example, the polarization is measured. In most cases, there is no correlation between these measurements. However in certain cases (certain reactions) when you measure the polarization in the x-direction then: if the direction of one photon is +x then the direction of the other photon is -x (or vice versa). That means the correlation between these two photons is -1. The most common-sense explanation is that this correlation is immediate established when the two photons are created. Is there any form of 'action at a distance' involved: No. Is it important that any of the photons is measured: No. The only thing you know that in some reactions if you measure the polarization of one photon, you immediately know the polarization of the other photon, as established by 1000 previous experiment.
5) In paragraph 4.3 the Bubble paradox is discussed.
Also here almost all the knowledge is collected by means of real experiments. In a more generic way what we have are two processes: One process over here, where a particle A changes in A' and emits a particle p. A second process over there, where a particle A' captures particle p and changes into a particle A. On a broader view, a particle A disappears over here and appears over there. What you first have to establish is that there is a correlation between these two events and if that is the case you can ask yourself the question how?
There are many reactions possible. The question is what can the particle p be? I expect an electron, a neutron, a neutrino etc. I expect that Einstein in some way or another thought that it could be a photon. I don't know if he had the reaction, explained in https://en.wikipedia.org/wiki/Electron_capture which involves the emission of a single x-ray photon, in his mind. But if that is the case it is most
logical to assume that this single photon is not emitted in a sphere (expanding in space) but more in a point, as a particle.
For more detail see: https://www.nicvroom.be/wik_Einstein's_thought_experiments.htm
The variables -v and +v represent the affect of the ether wind that MX is testing using the interferometer. Example, when you are riding you bicycle in the direction of the wind your velocity would increase (+v) because of the affect of the wind but when you a riding in the opposite direction your velocity would decreases (-v) where v represents the velocity of the wind; conversely, the light ray that is propagating in the direction of the ether wind would increase by c + v. Michelson is testing for the affect of the change in the velocity because of the light ray being affected by the ether wind but according to Einstein's postulate the velocity of light is constant in the moving coordinate system of MX experiment (earth's daily and yearly motions) which nullifies MX but Einstein later uses MMX to justify the existence of the ether, composed of matter, using relativity which depicts a contradiction since Einstein's postulate of the constant velocity of light is nullifying MMX, and, relativity is based on the constant magnitude of the ether wind but the ether wind varies.
|>||To read about this subject select: https://en.wikipedia.org/wiki/Einstein's_thought_experiments The final objective of any thought experiment is to perform each, in reality, and to test if the actual results agree with the predicted results.|
For more detail see:
1) In paragraph 3.1 'Falling painters and accelerating elevators' the equivalence principle is discussed. This principle is about Newton, who had pointed out that, even though they are defined differently, gravitational mass and inertial mass always seems to be equal.
IMO you can perform science without the concept of inertial mass.
The starting point is that you can make a difference between the physical
universe and the visible universe.
The physical universe is the physical state of all the objects in the total
universe at any one particular moment.
The visible universe is how we observe the physical universe at any one
particular moment. What we observe is the physical state in the past. The
further away we observe the earlier.
If we want to calculate the gravitational mass of the objects in the solar system we start from observations of the visible universe (at a sequence of events) for each object and we calculate a function which describes the trajectory of each object. Using such a function we calculate the position of each object in the physical universe. This transformation requires the speed of light.
Using these positions and with Newton's law we can calculate the gravitational mass of each object, including the Earth. Using that same method we can also calculate the mass of the moon. To calculate the gravitational mass of an iron ball we can in principle drop the ball from the tower of Pisa and observe its position and calculate its gravitational mass.
A better way is to bring the large iron ball in orbit and use exactly the same method as to calculate the mass of the moon. When we know the gravitational mass of an iron ball we can use that as a standard to measure the gravitational mass of all objects on earth.
(The calculated gravitational mass, based on observations, is fixed for each object. This makes it so difficult to understand why SR supports the concepts of variable mass as a function of rest mass)
2) In paragraph 4.2, the wave-particle duality of light is discussed.
Einsteins reasoning is based on "an imaginary mirror in a cavity containing particles of an ideal gas and filled with black body radiation, with the entire system in thermal equilibrium." The reaction observed is: "The mirror jiggles from Brownian motion due to collisions with the gas molecules." Einsteins reasoning is also based on 3 laws: "Planck's law", "Rayleigh-Jeans law" and the "Wien distribution law". IMO there is 'nothing' wrong with these laws. The problem is that each of these laws describes a certain process which has to be studied in relation to gas and photons (black body radiation). In that sense, it is more important first to find a qualitative explanation of why a photon behaves partly like a particle and partly like a wave and secondly a quantitative answer.
As part of the text is written: "Einstein could calculate the mean square energy fluctuation of the black body radiation." My question is can this calculation also be verified? (This has nothing to do with a thought experiment)
3) In a thought experiment normally two parties are involved. Generally speaking, both parties have the same knowledge. What makes thought experiments difficult that often (as state of art) the real experiments can not be performed, nor is all that is involved clear. As such both parties should show doubt and ask the other party for more explanations of what is meant.
In each thought experiment, only one experiment should be discussed, that means there only can be one physical explanation. If there are two explanations then at least one must be wrong. This allows that it is possible to find a simpler physical explanation. In SR often different reference frames are discussed. That is possible, but it should be clear that there is only one experiment.
In the previous discussion about gravitational mass, only one reference frame is used. That makes it simpler.
The same concept is used in the "VB train" simulation.
VB stands for Visual Basic, which is the programming language used in this simulation.
This simulation can also be called a thought experiment, but it is much more realistic. Only one reference frame is used. As part of the simulation, a distinction is made between visible and physical length contraction.
The simulation demonstrates visible length contraction, which is more like an illusion. The simulation also demonstrates physical length contraction but if that actually exists can only be demonstrated with a real experiment. Not with a thought experiment nor with a simulation.
4) For the interested reader I advise to read this article: https://www.nicvroom.be/ScientificAm_February_2020_The_enigma_of_aerodynamic_lift.htm "The enigma of aerodynamic lift" The article discusses two theories of why an airplane can fly. Both are considered wrong. In Reflection 2 I try to give my own explanation.
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