"""A: Many insights in physics go against common sense. For instance, it seems that the sun revolves around the earth, not vice versa. Yet the earth orbits the sun.""" explain this """It seems that a lead cannonball should fall faster than a peice of paper of equal size. Yet they fall at the same speed.""" You are repeating yourself. I have answered why this is not a good example. It is common sense because we don't live in vacuum and many objects have shapes which cause a lot of friction. ''''''It seems that light should be either a particle or a wave. But it is both, depending on how one chooses to observe it. ''''' repetition """"There is a great deal of evidence for general relativity. Not only does general relativity explain the orbit of Mercury""" I've seen other people explaining the perihelion of Mercurius without any relativity. And their results are the same. """but it also is confirmed in observations of gravitational waves.""" strange, I haven't heard of any discoveries of grav. weaves
Hi all, Tom, "You and James R, saw my results and saw that I was correct. Instead of admitting defeat, you and James R, claimed that I used the correct formulas for time dilation and length contraction, but that they weren't valid in the example I used (which, by the way, wasn't a complex example). I'm sorry, but I didn't fall for it, and I don't think that C'est Moi is falling for it either." That was one of our early conclusions yes, that the formulas you used were not valid. James R and I (although I can only speak for myself ofcourse, but I have a gut feeling James will agree here)... anyway... James R and I saw your results and saw that you were incorrect. Instead of admitting that, you refuse to read messages, or fail to see what they mean, when we try to explain how frames of reference work in relativity. Perhaps we just explained it in a too technical or completely uncomprehensible way, but be sure to tell us that then. There's no hidden masterplan or conspiracy amongst physicists to always back up Einstein's theory. I've already said a few times on the forums that what Einstein did was nothing special, if he hadn't come to his conclusions, some else would have very soon thereafter. He is not my personal god or something, just let's get that straight Please Register or Log in to view the hidden image!. c'est moi, "Define motion." It was you who started about the invariance of the motion of light. I just said that this was incorrect and that it was the speed of light that is invariant between observers. But if you want to hear it: motion - for me - is the change of position of an object with respect to a frame of reference. (referring to the preference of centre of mass or lab frame of reference when studying collisions) "you don't say why" Because the equations of conservation of energy and momentum simplify significantly in those frames of reference. Because those frames of reference are somewhat imaginable and therefor aid the understanding of the problem. "what does light do in the FOR of light? is it motionless?" If you move along with the light, then per definition it does not move from that frame of reference. "Have you proof for this?" Yes, take the limit v -> c in the formulas for time dilatation. "nobody explains why it is invariant unlike EVERYTHING else we know of" The invariance of the speed of light is a postulate in the special theory of relativity and hence not applicable for explanation. "btw, doesn't time dilation cause a change in the of speed of light" No, because by definition, per postulate the speed of light is c from your frame of reference. There is no need to measure it in the special theory of relativity. "Philosophy overrules physics and not the other way around, it's that simple." Without physics, philosophy would be on the same level as in the times of ancient Greece. Yes, it could all be a combination of earth, water, fire and air. Observation has thought us otherwise and has hence steered philosophy in another direction. But I'll partially agree with you and say that the interpretation of physical results is a matter of philosophy in some situations. But I think it is about time we start to settle this discussion - four threads and probably a thousand messages is becoming too much for us all to handle. Tom and c'est moi, would you be kind enough to give us your interpretation of the concept "frame of reference", how you can relate physical quantities of different frames of reference, and what the position of the invariance of speed of light is in your interpretations ? Bye! Crisp
Tom: It agrees with theory, does it not? It is not quite as accurate and much more complex than the Keplarian model. If you wish to be nihlistic about it. But prediction and simplicity are good evidences for the veracity of a theory. What about the wildly sucessfull and utterly bizzare theory of quantum mechanics? Sorry, I was a bit confusing with that example. I should have used lead weights of different sizes. C'est moi: Follow the movements of the sun across - oh fuck all! Even language reflects the conceit that the sun orbits the earth and not vice versa. And we live at relatavistic speeds? You prove my point for me. Relativity is not common sense because we do not live at relatavistic speeds. Or so goes my arguement. Verisimillitude. I'd appreciate it if you addressed the substance of my posts.... Oh? What people? What theories? And did their theories encompass as much as relativity does? And where might I see these results? Evidence....? Here's you go: source source My apologies if I was not clear enough on what I meant.
Crisp, Here is your final quote on the "How accurate are atomic clocks??" thread: Nor you nor James proved that the speed of light is c in a moving frame of reference "the hard way", as you put it, using only the traditional formulas. Instead, both of you were quick to disregard the traditional formulas, and focus on the Lorentz transformations when the traditional formulas didn't give you the result you desired. If you think you can prove that the speed of light is c in the example I provided, using only the traditional formulas, then do it. Don't pretend you did and then call me a liar. Tom
Xev, The theory of relativity states that time slows down. The slowing down of clocks is not the same as the slowing down of time. As 137(a member of sciforums) once said, "If I put my finger on the second hand of my watch to stop it from moving, my finger didn't stop time". Well, at least he said something like that. Please Register or Log in to view the hidden image! Tom
Tom: I agree. I am sorry if I was not clear enough earlier. I meant that the slowing down of a clock (which measures time) can be considered as evidence that time itself is slowing. Else why would the clock slow down?
Hi Tom, "If you think you can prove that light speed is c in the example I provided using only the traditional formulas, then do it. Don't pretend you did and then call me a liar." Wops, never intended to be offensive. However, the answer is in the quote you gave. What I refer to as the "hard" way is how James R initially calculated the speed of light, taking into account the motion of the observer (you probably remember that distances were added). You didn't approve of that way of calculating so we used the Lorentz transformations. I also explained how I think the Lorentz transformations take that distance James R had to add into account. So you are correct in saying that I never calculated it the hard way, James already did Please Register or Log in to view the hidden image!. There was also a reason why we disregarded the original formulas we worked with. I think that was explained also in the "how accurate are atomic clocks" thread. Bye! Crisp
Crisp, No offense taken. In a little while, I will post an example in the "How accurate are atomic clocks??" thread, that will prove that your and James' calculations are wrong. Tom
Xev, Relativists claim that the speed of light is constant in all frames of reference. If this was true then that would mean that atomic clocks are accurate at all speeds(because the electromagnetic fields in the clock would remain synchronized with the rest of the clock at all times). However, I found out that this is not the case. Light does not travel at c in all frames of reference it only travels at c in the absolute frame of reference. Because of this, the faster the clock is travelling the more the electric and magnetic fields become unsynchronized with the rest of the clock. This results in the clock slowing down. If you have the time read the "How accurate are atomic clocks??" thread from page 3. This should explain what I mean. By the way, I will be soon be adding a new post on the "How accurate are atomic clocks??" thread, on why Crisp's and James R's calculations were wrong. My next post on that thread will summarize everything I aid previously on that thread, so you only have to read my upcomming post to understand what the entire discussion was about. Tom
Tom: Okay, I guess we ought to agree to disagree? Be seeing you. Please Register or Log in to view the hidden image!
Tom Let's see what the dumbometer has to say about that one... Whoa! off the charts! From the earth's FOR the rocks fall to earth. From the moons FOR both fall to earth. From the point of view of one of the rocks the earth moves to it like you said. But then you take the FOR's of each rock at the same time, which i'm afraid gets a big BZZZZT, and a custard pie in the face. From the point of view of one rock the earthg moves towards it, and on the other side of the earth the other rock moves towards it faster and catches up with the earth. I'm surprised the big guns didn't give you a good slapping for that one.
Elmo From the point of view of one rock the earthg moves towards it, and on the other side of the earth the other rock moves towards it faster and catches up with the earth. Strangely enough, both rocks will view the Earth as moving towards it. It is not really a matter of logistics. Logic suggests the rocks are falling towards the Earth. But from the point of view of the rocks, it appears the Earth is moving towards them. Weird, huh?
I know, that's one of the things I love about physics. You see something like this and you go, "no way". Then you think about it and the penny drops. I just meant that Tom's way of viewing this seemed like he didn't really understand.
Q and Elmo, Well, I prefer logic over perception. If the two of you want to believe that the Earth moves towards the rocks, and that the Sun revolves around the Earth, then I'm happy for you. It's just fortunate that not all scientists, over the years, believed what you do. If they did, science would still be in the dark ages. Tom
Why all the fighting? Hi guys, newbie here. A little background in cosmology and science, so maybe I'll contribute something useful eventually.. Please Register or Log in to view the hidden image! But for now I don't understand something. What is the big conflict between relativity and absolute reference frames? Ok, it's true you can't define an absolute reference frame based on anything we know right now, but I don't think relativity excludes such a possibility. In relativity, that absolute reference frame would still be just another valid inertial reference frame, just like any other and all the laws and experimental outcomes would be identical regardless. Lots of people like reference frames defined in terms of mass or center of mass. I've seen even (Machian) theories linking inertia to the interactions among the total mass of matter in the Universe. FORs like that are not any more valid than any other; the universe is pretty democratic about it. Please Register or Log in to view the hidden image! My personal pet theory is that it ought to be possible to define an "absolute", "Universal" reference frame in terms of the cosmic background radiation. Since it's evenly distributed and emanates at the same (average) wavelength from all directions (skipping density variations...), then if you decide to move in any particular direction through that photonic "fog", you should see blue-shifted CBR in your direction of movement and red-shifted CBR in the opposite direction (well, once you filtered out various local gravitational effects...which are anisotropic, and should be easily distinguishable out of the spherical CBR distribution.) Such a reference frame is probably as close as we can currently come to an "absolute" spacetime coordinate system that is "universally" at rest. It would IMHO have a rather interesting property of having the average momentum over all matter in the universe, especially if the universe truly is infinite. Pretty remarkable, no? Please correct me if I'm missing something... Tom, If you insist that laws of physics change with relative speed, then Earth physics must be different from Sun physics, since we are not moving equally. As far as time slowing down (relatively speaking), it's only the measurement of time slowing down. After all, you can't define time in any other way, except for measurements. Same with distance shrinking; it's the measurement that is shrinking, not some absolute notion of distance (whatever it is...?) And if you think about it, in physical systems it's the measurements (a.k.a. interactions) that matter. So, if you can properly describe the behavior of such measurements (interactions), then you can fully decipher the workings of any physical system. Which, after all, is the goal...right?
overdoze, Welcome to sciforums!!! I agree with you about the fact that relativity does not exclude an absolute frame of reference. After all, if you subtract two relative motions, you get the same result as if you were to add the absolute motions to the two relative motions and then subtract them. However, everthing would be great and relative, if this was always the case, but it isn't. Relativity claims that the speed of light is c in all frames of reference, however I found that the speed of light is only c in the absolute frame of reference. This means that the speed of light in a relative frame of reference is dependent on the difference between the speed of the relative frame of reference and the absolute frames of reference. If you wish to see how I proved that light does not travel at c in all frames of reference, read the last page of "How accurate are atomic clocks??" thread. As you will find, I included time dilation and length contraction, and still came to the conclusion that light does not travel at c in moving frames of reference. You may ask, what does measuring time with an atomic clock have to do with the fact that the speed of light is not c in all frames of reference?? The answer is that atomic clocks consist of two types of components: relative components and unrelative components. The relative components of the clock are the physical materials that the clock is made of. They are relative components because they do not change based on the speed the clock is travelling. The unrelative components of the clock are the electromagnetic radiation that the clock uses to seperate and excite the caesium atoms. As the clock travels faster, these unrelative components change because, as I stated before, the speed of light is not constant at different speeds.(Even though the microwaves and electric and magnetic fields in the clock are not light, they are electromagnetic radiation, just like light). The conclusion is that the faster an atomic clock travels, the more the unrelative components of the clock become unsynchronised with the relative components of the clock. This leads to the clock slowing down, while time, in reality, does not. Finally, the only way to measure time accurately using an atomic clock would be to adjust the readings of the atomic clock to compensate for the unrelativistic components of the clock. But this can never be done as long as physicists believe that the speed of light is c in all frames of reference. Tom
Tom, I've just read your post in "how accurate are atomic clocks" summarising your "proof" that light does not travel at c in all FsOR. Your proof is based upon the assumption that the speed of light does not equal c in all FsOR. Its therefore basically flawed. I'd also like to point out that when scientists went looking for the ether they performed detailed experiments looking for differences in the speed of light in different FsOR. Guess what, they found c was invarient.
If you read my posts you will find that I took the distance that light travelled away from the observer in two examples: 1) When the flashlight is shining in the same direction of the motion of the observer. and 2) When the The flashlight is shining in the opposite direction of the motion of the observer. I took these two values and converted them into the moving observer's frame of refernce using time dilation and length contraction. I found that for only one of the examples can light be equal to 300,000 km/s. In other words, in the other case, the speed of light will not be c. I will shortly post a a simplified example of the problem on the "how accurate are atomic clocks" thread. You should read it, you'll find it interesting. Tom
Hi Tom, Something you said doesn't make much sense: Reality is that all components of atomic clocks are relative. The "physical materials", if you remember, are in fact equivalent to electromagnetic energy according to e=mc^2 -- and this has indeed been proven in particle accelerators. So in fact, it's just different forms of the same stuff (you can think along the lines of a condensation analogy, where matter is just condensed -- or concentrated -- energy.) Many components of matter carry charge (e.g. protons, electrons) -- that's an electromagnetic component and is as sensitive to propagation through the electromagnetic field as photons themselves. There is also an unspoken idea that all fields -- electromagnetic, strong, weak, gravitational -- are merely different manifestations of a common underlying medium ("unified field theory"). Einstein himself tried, though fruitlessly, to come up with such a unification for the rest of his life after he completed GR. Another thing is that the speed of light is constant -- for the inertial observer -- no matter how the observer is moving. Maybe if I argue from an imaginary absolute perspective, it would click for you. So, assume that you are the absolutely motionless observer, and three bodies A, B, C are travelling away from you along parallel vectors (the distance between them doesn't change.) They travel at a speed v very close to c, and to demonstrate that you shoot a photon in their direction and observe that while the photon is receding from you at speed c, it is catching up to these bodies and overtaking them much slower. The bodies are arranged as follows: A and B are arranged along a line orthogonal to their direction of motion, while A and C are arranged precisely along the direction of motion, with distance between A and B being the same as the distance between A and C (from your perspective) so that ABC is an equilateral right triangle like this: <tt><pre> C /\ | (direction of motion) A B | you </pre></tt> For now let's just presume that there is no time speedup or slowdown for A as compared to your time. Case (1) Suppose A wants to determine the distance to C, which in your frame of reference is D. To perform the measurement, A is going to bounce a photon off C and use the speed of light to calculate the distance. Going from A to C, the photon (from your point of view) is going to take D/(c - v) seconds to reach C, and then from C to A it's going to take D/(c+v) seconds. The round-trip time is 2D/(c-v^2/c), which is larger than 2D/c if A and C were stationary in your FOR. What that means is that A is going to think the distance to C is larger than you observe it to be. Flipping the perspective, you are going to think the distance from A to C is shorter than A observes it to be. Case (2) Now suppose A wants to measure the distance to B. In your FOR it's also D. But as A bounces a photon off B, in your reference frame the photon is actually describing an equilateral triangle with height D since both A and B are moving away from you. The trip from A to B will take exactly the same amount of time as the trip from B to A, and the total roundtrip time will be twice that. To solve for the one-way-trip time, we have this equation: v^2t^2 + D^2 = c^2t^2, from which we get total roundtrip time to be 2D/sqrt(c^2-v^2). This is larger than 2D/c that would correspond to the distance you observe. Conclusion (1) All other vectors of interaction between A and any co-moving body would consist of AC and AB components (in 3 dimensions, there would be another commponent that sticks out of the page that would behave identically to AB.) So it turns out that for the moving bodies all the distances are effectively larger than what you observe. Since all interactions are confined to light speed, for the moving bodies every single interaction will take longer, in effect resulting in a slowdown of time. That is, you are going to see all the processes slowed down in the moving bodies. Conclusion (2) If you do the math, you will observe that the apparent lengthening of distance from A's perspective is greater along the AC direction than along the AB direction. So, in addition to an overall slowdown in time there is a supplemental "length contraction" (from your FOR) along the direction of motion, or conversely a "length dilation" from A's FOR along direction of motion. As you can see, the good old Lorentz transformations just pop out naturally even as you start with an absolute FOR (in fact, Lorentz derived his transformations long before Einstein had his breakthrough.) Einstein's great leap of insight was that in the real world there is no way to determine whether a body is absolutely at rest. So in fact, all inertial frames of reference should be equivalent if the universe with all of its haphazardly careening bodies is to be consistent as far as physics goes. Thus he started with the principle of equivalence as his fundamental assumption, and re-derived the Lorentz transformations in a relativistic framework. What this means, is that no matter your FOR, as long as it's inertial the math always works out identically (and later Einstein extended the theory to accelerated reference frames, in what he called GR.)
Overdoze, After reading your post, I have to say that I do agree with you. Light would take longer to travel from one object to another and back again if the objects are moving. This in effect is proof that light does not travel at c in all frames of reference. If it did, then light would take the same amount of time to travel from one object to another whether they are moving or stationairy. However, Einstein couldn't accept these results because that would mean that there was an absolute frame of reference, so he decided to create time dilation and length contraction to MAKE light move at c in all frames of reference. However, as I have pointed out in the "How accurate are atomic clocks??" thread, even if you take time dilation and length contraction into consideration, the speed of light is still not c in all frames of reference. Tom
