Is Length Contraction in SR physical??
in [Relativity]
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From: Ste on 9 Feb 2010 04:38 On 9 Feb, 05:27, mpalenik <markpale...(a)gmail.com> wrote: > On Feb 9, 12:19 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > Incidentally, does frequency have any effect on the absorbtion time of > > electromagnetic radiation? > > The absorption probability (per unit time) goes to zero when averaged > over large time scales unless the frequency is equal to the energy > difference between two quantum states of the absorbing particle. I'm afraid that answer was beyond my comprehension.
From: Ste on 9 Feb 2010 04:57 On 9 Feb, 05:41, mpalenik <markpale...(a)gmail.com> wrote: > On Feb 9, 12:38 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > On 8 Feb, 16:30, PD <thedraperfam...(a)gmail.com> wrote: > > > > I don't know why you think that physical models MUST meet your > > > criteria of "physical" (how YOU understand that term rather than how > > > physicists understand that term) and "classical" in order to be > > > acceptable to you. > > > > Note that the REQUIREMENT you impose that the explanation be classical > > > is simply an assertion that anything that does not meet the classical > > > mold is not to be entertained as viable. This is a personal choice on > > > your part that you will ONLY believe that which meets the classical > > > physics mold and simply NOT BELIEVE anything else. > > > I've been quite clear Paul. Everyone has axioms, everyone has > > requirements. Stop framing the issue as though you, or "science", > > don't. > > That's a problem when the axioms contradict reality. For example, if > I say as one of my axioms that any law of physics must work within the > Aristotilian framework, that would preclude my acceptance of any > theory that truly models reality. > > Similarly, your insistance that any physical theory works within a > classical framework precludes your acceptance of any theory that truly > models reality. Yes, but let's be clear that when I say a "classical framework", I don't mean that we can't replace the maths of classical theory; that can go, if necessary. The important thing that must stay is the physical, intuitive, mechanical nature of it - what Paul calls the "cogs and levers" approach. Of course, even then, reality does not have to resemble cogs and levers in corporeal sense - even electromagnetism clearly doesn't involve anything corporeal - but reality must retain its predictive and systematic nature that is inherent in mechanical relationships.
From: paparios on 9 Feb 2010 09:22 On 9 feb, 03:19, Ste <ste_ro...(a)hotmail.com> wrote: > On 8 Feb, 16:57, PD <thedraperfam...(a)gmail.com> wrote: > > I'm curious, what is this "spacetime quantity"? Is it something like > "total volume"? Consider two reference systems K and K' moving relative to each other with a constant velocity v. We choose the coordinate axes so that the axes X and X' coincide, while the Y and Z axes are parallel to Y' and Z'; we designate the time in the systems K and K' by t and t'. Consider one event, which consist of sending out a signal, propagating with light velocity, from a point having coordinates (xl, yl, zl, t1) in the K system. We observe the propagation of this signal in the K system. Consider a second event consisting on the arrival of the signal at point (x2, y2, z2, t2). The signal propagates with velocity c; the distance covered by it is therefore c(tl - t2). On the other hand, this same distance equals [(x2 - xl)^2 + (y2 - yl)^2 + (z2 - zl )^2]^1/2. Thus we can write the following relation between the coordinates of the two events in the K system: (x2 - xl)^2 + (y2 - yl)^2 + (z2 - zl )^2 - c^2 (t2 - tl)^2 = 0 (1) The same two events, i.e. the propagation of the signal, can be observed from the K' system: Let the coordinates of the first event in the K' system be (x1, y1, z1, t1) and of the second: (x2, y2, z2, t2). Since the velocity of light is the same in the K and K' systems, we have, similarly to (1): (x2 xl)^2 + (y2 yl)^2 + (z2 zl )^2 - c^2 (t2 tl)^2 = 0 (2) If (xl, yl, zl, t1) and (x2, y2, z2, t2) are the coordinates of any two events, then the quantity sl2 = [c^2 (t2 - tl)^2 - (x2 - xl)^2 - (y2 - yl)^2 - (z2 - zl )^2]^1/2 (3) is called the interval between these two events. Thus it follows from the principle of invariance of the velocity of light that if the interval between two events is zero in one coordinate system, then it is equal to zero in all other systems. If two events are infinitely close to each other, then the interval ds between them is ds^2 = c^2 dt^2 - dx^2 - dy^2 - dz^2. (4) The form of expressions (3) and (4) permits us to regard the interval, from the formal point of view, as the distance between two points in a four-dimensional space (whose axes are labelled by x, y, z, and the product ct). Miguel Rios
From: kenseto on 9 Feb 2010 09:28 On Feb 9, 12:02 am, artful <artful...(a)hotmail.com> wrote: > On Feb 9, 2:53 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > The question is whether the scientists who claim to understand SR > > actually do understand it in a physical way, or whether they have just > > learned the maths by rote and swallowed the fallacious explanations > > they've been given for what they observe. > > Please put forward what explanations of SR you are referring to, and > your evidence / logical argument that proves they are fallacious. > Please also provide non-fallacious explanations as alternatives. For example in the barn and the pole paradox: Sr says that a 80 ft pole can fit into a 40 ft barn completely with the ends of the pole not sticking out of the barn. At the same time SR claims that the same pole cannot fit into the barn completely and the ends of the pole is sticking out of the barn.
From: Peter Webb on 9 Feb 2010 10:13
It would be baffling for someone to say that you could change the length of the ladder by rotating the house, and yet geometrically this is perfectly valid - but note that we're still able to create physical analogies for these mathematical concepts. _________________________ You don't get it. Length does get shorter, and time slows down. The ladder really does fit inside the barn. Pity, your idea of length is not actually an invariant, the ladder really is shorter if it moves faster. If you want the invariant - the thing that doesn't change with relative speed - that is the Minkowski 4 vector, and the length of that is unchanging length of the ladder. At rest, they are the same. |