Eise

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Eise last won the day on February 11

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About Eise

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    the old world
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    Physics, Astronomy
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    University degree philosophy, subsidary subject physics
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    Database administrator, a bit of Linux too

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  1. Hi Michel, I think you should see that your way of depicting real numbers and imaginary numbers leads to mathematical nonsense. You cannot treat imaginary numbers as if they are just some additional numbers to the real numbers. If you want to combine the two in one concept, i.e. in complex numbers, you need an independent depiction, in which real numbers and imaginary numbers are two different dimensions. Imaginary numbers do not fit on the real-number line: therefore you cannot say that i is greater or smaller than 1, or even zero. So i is not negative, and it is not positive. -i is just the inverse of i under summation, meaning that -i + i = 0. So complex numbers are more like 2-dimensional vectors: one axis is the real axis, the other axis is the imaginary one. Now multiplication becomes an interesting phenomenon. If you make a drawing (real axis horizontal, imaginary axis vertical) you can see what happens if you multiply complex numbers. Example: Take the complex number sqrt(3) + 1.i and calculate the square: You get: 3 + 2.sqrt(3).i + (i.i) 3 + 2.sqrt(3).i - 1 2 + 2.sqrt(3).i What can you say about this calculation in terms of vectors? As you know vectors have a length and an angle. So e.g. the 'length' of i is 1, just as the lengths of 1, -1 or -i. Length: Pythagoras: Length of sqrt(3) + 1.i: sqr(sqrt(3)) + sqr(1) = 3 + 1 = 3 + 1 = 4 => the length is sqrt(4) = 2. Length of 2 + 2.sqrt(3).i: sqr(2) + sqr(2.sqrt(3)) = 4 + 4.3 = 4 + 12 = 16 => the length is sqrt(16) = 4. So the length of the product is the product of the lengths. And that fits consistently to numbers that lie on the real axis only! No inconcistency. Now if you would look at the angles (use goniometry) you will discover that with multiplication of 2 complex numbers, you must add the angles. So what happens when you square e.g. 1 + i? The angle is 45o, so double the angle of the square: it is 90o. The length of the 'vector' 1 + i is sqrt(2), so the length of the result will be 2. 90o means the result lies on the imaginary axis, so the answer is 2i. Calculation: sqr(1 + i) = 1 + 2.i + i.i = 1 + 2.i - 1 = 2i. That fits. This formalism is used everywhere where complex numbers are used. E.g. Richard Feynman, in his pop-science book about QED, uses rotating arrows and their vector addition and multiplication to explain QED. But of course, he really is talking complex numbers, using the vector depiction. The whole building of physics would break down, if this way of treating complex number would be wrong. Does that help a bit?
  2. I am working at a company that trades in nuts and bolts. They have an X-ray device for analysing the metals of which the nuts and bolts are made (quality control). As I understand this, for many metals just the electrons in the outer shells do not distinguish between all the metals: with the X-rays one can reach electrons at deeper shells, and from the produced spectral lines that are emitted, one can conclude which metals are used. If I understood something wrong, please correct me. OK, just looked it up: it is called X-ray fluorescence.
  3. This is totally beside the point. I explained in what way the uncertainty principle is related to the mathematics of waves, so it is valid for any wave phenomenon (sound, light, waves on water). it has nothing to do with a measurement process, and so is not related to the observer effect. You do realise that I gave some precise arguments, and you do not countered them at all? You just make some sweeping statement ('HUP is about phenomena with momentum/position') which is only partially true (it exists also with energy/time), and is definitely false when you consider none-wave phenomena. You backed up that there are many examples of the 'observer effect', and there I agree with you. However, depending on what is measured, there are different mechanisms that are causing it. Knowing these mechanisms, it gives clues about improvements of your measurement methods, to minimise or even get rid of the observer effect. But the HUP says something different: wave phenomena are basically unsharp, not because our measurement is not precise enough, or we have any effect on the phenomenon we are observing (of course we have too, but that it is not what the HUP is about), but that is inherent to waves. I had a look into Studiot's video. Again, the author is very clear (at 15:35):
  4. Itoero, You fail to see 2 things: Uncertainty is a basic principle for every kind of wave, not just in QM. A long sinusoidal wave has a pretty precise frequency, but is of course smeared out over a longer distance. So its position is not precise. It doesn't mean that we cannot determine it precisely, it is not precise. Opposite with a small wave packet (e.g. a sound bang): it has a pretty precise position, but not a precise frequency. See e.g. this illustration: The wave packet is a combination of waves with different frequencies: this means the wave has no precise frequency. Just note that there is no reference to QM here at all. It is a fundamental property of waves. Two none-QM examples: An AM radio station that is not modulated, has a precise frequency, e.g.70 kHz. You do not measure a signal at e.g. 69 kHz. However, as soon as the signal is modulated, it looks like this:This causes a spread in frequency. On your radio, you can already receive the radio signal e.g. at 67 kHz, until 73 kHz. This is the reason that for AM the audio frequency is artificially reduced, to avoid that the spread becomes too big, and radio stations would disturb each other. Also on your AM radio: if a thunderstorm is approaching you can hear the lightning as a cracking sound. Interesting is that you hear them on any frequency, you do not have to tune in on exactly the frequency of the lightning. And why? Because such a short EM pulse really contains all frequencies. It is not that we cannot determine the frequency, the pulse has no precise frequency. So the unsharpness of waves is a real effect, not an effect of us measuring it. And its effect is explained by Fourier analysis, which is a mathematical procedure, not some pure physical effect. If a natural phenomenon behaves like a wave, it will behave like the mathematics of waves. The second thing you do not see is that the Schrödinger wave function is not a simple physical object: we cannot measure it. We can only measure particles arriving at some point. If we repeat our measurements, we can empirically determine what the square of the wave function is (it is the chance distribution of our measurements). But e.g. we cannot measure the phase of the wave function. And it also does not make sense: the Schrödinger wave function is a complex function, i.e. it has a imaginary component (square root of -1, such stuff...). So, to speak of a physical effect (as the observer effect is) on something that is not physical does not make sense. And further I am astonished that several experts here (Swansont, Mordred, Studiot) and I tell you that you are wrong, give clear arguments for that view, and back them up with articles, and you still stick to your wrong view point. PS Click on the links to see the graphs. I do not know why, but I saw them in my posting when I was writing the post, now they are just links.
  5. Hi Michel, I do not see your problem. Everytime when one extends the set of numbers you get surprises: N: 1,2,3,4,... When multiplying 2 natural numbers the result is always >= both numbers. Z: ... -2,-1,0,1,2... Ups, the above rule is not valid anymore: -2 * 4 = -8: the result is smaller than both numbers! Same if you use Q+: 0.1 * 0.2 = 0.02: again, the result is smaller than both numbers. Now with imaginary numbers you get the next surprise: where in the above sets at least the square of a number is always positive, this is not so with imaginary numbers. (i)2 = -1, as is (-i)2. So rules that seem general (plus times plus makes plus, minus times minus makes also plus) for a subset of all numbers (Z, Q, R), is not valid for C anymore. And as Studiot also explained, the principle of ordering (greater, smaller) in C does not work. The question if i is greater than 1 does not make sense. Therefore C is depicted in a two dimensional plane.
  6. Yes, that is obvious... Let's go to the basics. Imagine you have a picture: showing e.g. a mountain far away, and a flower on the foreground. Due to the big distance between the flower and the mountain they cannot be both sharp, and the photographer has chosen to have the flower sharp, and the mountains unsharp. E.g.: Now imagine you want to make a photograph of this photograph. If you choose your focus completely wrong everything will be unsharp. This you could call the observer effect (not quite of course because you do not influence the picture by photographing it). But you can make the picture sharper: but whatever you do, you won't get the mountains sharp, because on that picture the mountains themselves are not sharp. And that is not due to your way of photographing. It is due the picture itself. And so it is with the HUP: it expresses a feature of the object in question itself, namely of a quantum particle. It has nothing to do with the way of measuring.
  7. Eise

    Redundant Expressions in Science

    Do you always react only on half-sentences? Read the complete question, and answer it as a whole: So I am not asking if animals have goals (yes, they have), but I am asking if they breed selectively based on what they want to reach with it (faster horses, fatter pigs, white mice...). Did you ever see lions breed slower gazelles, because they are easier to catch? In reality, their evolutionary pressure 'breeds' faster gazelles.
  8. Eise

    The theory of space /time

    You do not seem to know what a pendulum in a pendulum clock is for. The property of a pendulum, that its period for relatively small amplitudes is constant. Its period is given by the formula: T = 2π x sqrt(L/g) So only the length of the pendulum, and the strength of gravity is relevant. The above formula is valid for earth, where g = 9.81 m/s2. But if g is lower, as on the moon, then the period becomes longer (a factor of sqrt(6), assuming that the gravity on the moon's service is 1/6 of that of the earth). So a pendulum on the moon is slower. And this has nothing to do with the strength of the spring. The spring is only needed to replace the energy that is lost due to friction. As a thought experiment, imagine a pendulum without friction. It will have a longer period on the moon than on earth. But we know from general relativity that time goes slightly faster on the moon than on earth, seen from a remote point far from the moon and the earth. And 'slightly', much less than a factor of sqrt(6). What you do not realise is that gravity is in fact a change of geometry: there is no physical effect that lets time slow down in gravity. Or maybe clearer: there is no physical mechanism for time slowing down in a gravity field. It is the perspective that is different, due to spacetime-curvature.
  9. Eise

    Redundant Expressions in Science

    Hrvoje1, you happily ignored what I wrote. I made it bold for you:
  10. I won't discuss that, but what the essential difference between the general observer effect is, and the HUP. The general observer effect is between physical objects: the object that is measured, and the object that measures. This is not so with the HUP. The wave function is not a physical object as other physical objects. And the HUP follows from the fact already mentioned by Swansont, that e.g. position and momentum are Fourier transformations of each other. It is not so that we have some physical effect on a physical system: their combination is not precise, independent from the fact if we measure it or not. And in not-measuring is definitely not an observer effect. You really think that Strange does not know that a photon has an energy according to E = hf? The question here is if you can call it kinetic energy. I am not sure, so I let it to him argue about this with you. But at least one difference is that you can make the kinetic energy of moving bodies 0 by slowing it down. You cannot do that with a photon. It always travels at c. But knowing that like to subsume as many concepts as possible under the same word, I understand your point... .
  11. Eise

    The theory of space /time

    Imagine a stationary pendulum clock on a big distance of the earth. As it is farther from earth, gravitation is less than on the surface. Questions for you: - does it run faster or slower than the same clock on earth? - what does general relativity predict? Faster or slower? - Does that fit with the fact that GPS works? Now it is even worse: GPS satellites are not stationary, they orbit the earth freely, i.e. they are in free fall around the earth. This means everything on board is weightless, as if there is no gravity at all Questions for you: - does the pendulum clock work? Or does it stand still - if nothing on board points to the fact that there is gravity, why do we still need to compensate for gravitational time dilation?
  12. Eise

    Light clock - basic explanation needed

    Trying the simplest explanation that hopefully is physically correct. At the basis of special relativity stand the 2 postulates. For this purpose I switch the order, and reword them a little: the speed of light is the same for every observer when frames of reference move uniformly relative to each other, the laws of nature are exactly the same. You already used the first postulate to understand that a light clock moving relatively to you is 'ticking' slower. So far so good. But now, we add a mechanical clock to the light clock. when both stand still from my point of view they tick in exactly the same pace. But what do I see when I look at both together, passing me with high speed? If it is true what you said, that the light clock is just wrong, then the mechanical clock and the light clock do not run in pace anymore. So I can conclude that both are moving, and I am not. When I travel with both together, and they would run out of pace, I could conclude that I am moving. But this is in contradiction with the second postulate. The light clock would run slower than the mechanical clock, so the laws of electromagnetism would be different for me. So you need both postulates to understand why time, i.e. all processes, appear to slow down for an observer moving relatively to me.
  13. Eise

    Redundant Expressions in Science

    OK, you are right I could have been more precise: evolution has no goal. Is it now correct? Or do monkeys and dogs do selective breeding, based on the output they want to reach? For the rest, I think you are spoiling your time. What is next: are you going to criticise physics because the 'up'-quark does not point up? You must distinguish between concepts and words. When you would critisise concepts, then your criticism would at least be pointed at something substantial. But you are criticising wordings. What means 'artificial'? Please explain in your own words (no dictionary!). Please give some examples.