Moronium Posted June 28, 2018 Report Posted June 28, 2018 (edited) I really don't care to get into semantical arguments. As I've said, I am concerned about speed, which requires no direction. When I first stated, in my hypothetical, that the relative velocity between A and C was .9c, nobody insisted that was NOT a velocity then. If it wasn't, then what WAS the velocity? Would I have to said said they were both moving "north," or something? If I had, would that have changed anything? The whole hypothetical tacitly presupposes constant velocity (i.e., in a straight line at constant speed). Direction is insignificant here. If you don't like the author saying that velocity is a vector, just read him as saying that, in one dimension, speed and velocity are equivalent. Edited June 28, 2018 by Moronium
Vmedvil2 Posted June 28, 2018 Report Posted June 28, 2018 (edited) I really don't care to get into semantical arguments. As I've said, I am concerned about speed, which requires no direction. Where I first stated, in my hypothetical, that the relative velocity between A and C was .9c, nobody insisted that was NOT a velocity then. If it wasn't, then what WAS the velocity? Would I have to said said they were both moving "north," or something? If I had, would that have changed anything? The whole hypothetical tacitly presupposes constant velocity (i.e., in a straight line at constant speed). Direction is insignificant here. Speed and velocity are the same-thing both of which require a direction to be moving the definition of velocity or speed is Meters per Second or dx/dt = V which means a directional movement over time, it is definitely a vector making direction very relevant, what is not relevant is their motion from each-other but rather the motion from a frame at rest. I am telling you it is impossible for a object or set of objects to go faster than the speed of light. It is science fact, the fastest two objects can move is E = MC2 , which the velocity of a matter field is C2 being V = C in X+ and X- being a mass-less object like a photon until tachyon condensation it is impossible to move faster than E = MC2 , which would be two objects moving away from each-other at V>C. The actual constant will not allow it for max velocity of any field with mass. You get a negative value or 1/0 = ∞ which not even the Higgs field can tachyon condensate for long without bleeding energy into mass which is how mass is generated from particles moving at the speed of light or slightly above called Tachyon Condensation or the Higgs Mechanism. ' Edited June 28, 2018 by VictorMedvil
A-wal Posted June 28, 2018 Report Posted June 28, 2018 (edited) No, I honestly can't see that. If I put $10 in the bank, then withdrew five, I wouldn't find it impossible to conclude that there was $5 left in the bank just because the two transactions were in "opposite directions." $5 would still be the "simple sum."Currency isn't subject to a monetary addition formula. Actually it kind of is, if you keep printing money you devalue what's already in circulation. But it's relative to the total value of the currency so you'd need to put a lot of new money in the bank for there to be less than half that value when you draw half of it out, and I'm drunk so I'll stop now in case I'm taking complete bollocks. Calling it the closing/opening speed instead of relative velocity does kind of make sense because it prevents mixing up speeds that are relative to the observer with speeds of two other objects relative to each other, but the fact remains that they're moving at 1.2...c relative to each other in B's frame of reference. You said that using the velocity addition formula to answer your question is answering the wrong question, so if you question is different to the one you wrote how are we supposed to know what you're actually asking. Obviously we're going to use the velocity addition formula, that's how you get the relative velocity. If you're asking how you can know that the velocity addition formula is valid then it's because the speed of light has been repeatedly shown to not depend on the relative velocity of the emitter and the velocity addition formula is how you keep the speed of light constant for all inertial objects despite their velocities relative to each other. Also the mass increase of particles relative to the lab matches with it and that could only happen with a preferred frame if the lab happened to be exactly at rest relative to that preferred frame, which isn't plausible considering the Earth's motion relative to the sun, the galaxy, the Virgo cluster or any other arbitrary choice of a coordinate system to measure motion relative to. Edited June 28, 2018 by A-wal OceanBreeze 1
Moronium Posted June 28, 2018 Report Posted June 28, 2018 Speed and velocity are the same thing OK, let's just leave it there then, and stop arguing about irrelevant things. My understanding is a little different, but that's OK.
Vmedvil2 Posted June 28, 2018 Report Posted June 28, 2018 (edited) Currency isn't subject to a monetary addition formula. Actually it kind of is, if you keep printing money you devalue what's already in circulation. But it's relative to the total value of the currency so you'd need to put a lot of new money in the bank for there to be less than half that value when you draw half of it out, and I'm drunk so I'll stop now in case I'm taking complete bollocks. Calling it the closing/opening speed instead of relative velocity does kind of make sense because it prevents mixing up speeds that are relative to the observer with speeds of two other objects relative to each other, but the fact remains that they're moving at 1.2...c relative to each other in B's frame of reference. You said that using the velocity addition formula to answer your question is answering the wrong question, so if you question is different to the one you wrote how are we supposed to know what you're actually asking. Obviously we're going to use the velocity addition formula, that's how you get the relative velocity. If you're asking how you can know that the velocity addition formula is valid then it's because the speed of light has been repeatedly shown to not depend on the relative velocity of the emitter and the velocity addition formula is how you keep the speed of light constant for all inertial objects despite their velocities relative to each other. Also the mass increase of particles relative to the lab matches with it and that could only happen with a preferred frame if the lab happened to be exactly at rest relative to that preferred frame, which isn't plausible considering the Earth's motion relative to the sun, the galaxy, the Virgo cluster or any other arbitrary choice of a coordinate system to measure motion relative to. You have to take all their velocities from that of a Frame at Rest in order for Special relativity to work correctly using the proper vector equations, you have to know a little math to use Relativity properly but once you learn it, it is like using a universal equation for motion that always works, which it is one of Einstein's Masterpieces that is never wrong, not even in the quantum world is it wrong and even merges with Quantum Field Theory, SR is always correct, if it is wrong you are not using it properly. Now GR, is another story but SR is never wrong being a Invariant equation of motion being E8 or Real Universe. Edited June 28, 2018 by VictorMedvil
Moronium Posted June 28, 2018 Report Posted June 28, 2018 (edited) I am telling you it is impossible for a object or set of objects to go faster than the speed of light. It is science fact I know that's what you're "telling" me. The velocity addition formula would not even exist if not for that presumption. I disagree that it is a "scientific fact," however. It is a theoretical conclusion based on the postulates of SR--"fact" is not even an appropriate word to use in that context. Edited June 28, 2018 by Moronium
Moronium Posted June 28, 2018 Report Posted June 28, 2018 (edited) OceanBreeze, on 28 Jun 2018 - 2:31 PM, said:The relative velocity between B and C is 0.756c Is that the speed B will actually "see," using the doppler effect to gauge his speed relative to C, or is that just what he (or I guess I should say you) will calculate? This is a repost. I haven't seen where I got any answer to this question, so maybe it got overlooked. Edited June 28, 2018 by Moronium
A-wal Posted June 28, 2018 Report Posted June 28, 2018 (edited) You have to take all their velocities from that of a Frame at Rest in order for Special relativity to work correctly using the proper vector equations, you have to know a little math to use Relativity properly but once you learn it, it is like using a universal equation for motion that always works, which it is one of Einstein's Masterpieces that is never wrong, not even in the quantum world is it wrong and even merges with Quantum Field Theory, SR is always correct, if it is wrong you are not using it properly. Now GR, is another story but SR is never wrong being a Invariant equation of motion being E8 or Real Universe.Qué? 1. Did you get the impression I was asking how and why apply SR? 2. No you don't need any maths knowledge at all. I never use the velocity addition formula but I've made a couple of 'educated' guesses of relative velocities in recent posts just by thinking thinking about what it would roughly have to be to keep the speed of light constant. 3......it is like using a universal equation for motion that always works, which it is one of Einstein's Masterpieces that is never wrong, not even in the quantum world is it wrong and even merges with Quantum Field Theory,Bollocks! Edited June 28, 2018 by A-wal
A-wal Posted June 28, 2018 Report Posted June 28, 2018 I know that's what you're "telling" me. The velocity addition formula would not even exist if not for that presumption. I disagree that it is a "scientific fact," however. It is a theoretical conclusion based on the postulates of SR--"fact" is not even an appropriate word to use in that context.If you're asking how you can know that the velocity addition formula is valid then it's because the speed of light has been repeatedly shown to not depend on the relative velocity of the emitter and the velocity addition formula is how you keep the speed of light constant for all inertial objects despite their velocities relative to each other. Also the mass increase of particles relative to the lab matches with it and that could only happen with a preferred frame if the lab happened to be exactly at rest relative to that preferred frame, which isn't plausible considering the Earth's motion relative to the sun, the galaxy, the Virgo cluster or any other arbitrary choice of a coordinate system to measure motion relative to.You can keep on ignoring this because it doesn't support what you want to be true but it won't go away, the truth never dies once it's found. Is that the speed B will actually "see," using the doppler effect to gauge his speed relative to C, or is that just what he (or I guess I should say you) will calculate? This is a repost. I haven't seen where I got any answer to this question, so maybe it got overlooked.It's the actual relative velocity. The velocity addition formula isn't something that's retroactively applied, it's how you can work out what the actual relative velocity would be!
Vmedvil2 Posted June 28, 2018 Report Posted June 28, 2018 (edited) Qué? 1. Did you get the impression I was asking how and why apply SR? 2. No you don't need any maths knowledge at all. I never use the velocity addition formula but I've made a couple of 'educated' guesses of relative velocities in recent posts just by thinking thinking about what it would roughly have to be to keep the speed of light constant. 3...Bollocks! it is invariant which in math term means never wrong, QFT can be made relativistic and is still correct with the addition of SR. Secondly, you did it correctly, you have to use the inverse Del operator or (dx,dy,dz) which is just the modified Pythagorean theorem. Edited June 28, 2018 by VictorMedvil
Moronium Posted June 28, 2018 Report Posted June 28, 2018 (edited) It's the actual relative velocity. The velocity addition formula isn't something that's retroactively applied, it's how you can work out what the actual relative velocity would be! Is that a yes or a no? You didn't answer the question, at least not directly. Is that the reading B would get on his doppler instruments? Edited June 28, 2018 by Moronium
Vmedvil2 Posted June 28, 2018 Report Posted June 28, 2018 (edited) Is that a yes or a no? You didn't answer the question, at least not directly. Is that the reading B would get on his doppler instruments? There would be no doppler unless you were in a gravitational field, in which case it would slow the velocity of the moving object redshifting it making it appear to move slower. Edited June 28, 2018 by VictorMedvil
A-wal Posted June 28, 2018 Report Posted June 28, 2018 it is invariant which in math term means never wrong, QFT can be made relativistic and is still correct with the addition of SR. Secondly, you did it correctly, you have to use the inverse Del operator or (dx,dy,dz) which is just the modified Pythagorean theorem. Really? SR works with QM and it's just GR that doesn't? Are you sure? Is that a yes or a no? You didn't answer the question, at least not directly. Is that the reading B would get on his doppler instruments?Yes, but not because of distorted instruments (time dilation/length contraction). Well sort of it's because of TD and LC but not really because nobody is time dilated/ length contracted from their own point of view and their own point of view (in which observers in motion relative to them are time dilated and length contracted) are equally valid.
Moronium Posted June 28, 2018 Report Posted June 28, 2018 There would be no doppler unless you were in a gravitational field, in which case it would slow the velocity of the moving object redshifting it making it appear to move slower. How did A and C determine their relative speed? What method would they use?
A-wal Posted June 28, 2018 Report Posted June 28, 2018 There would be no doppler unless you were in a gravitational field, in which case it would slow the velocity of the moving object redshifting it making it appear to move slower.Not true! Doppler shift is what the redshift of distant galaxies is an example of.
Vmedvil2 Posted June 28, 2018 Report Posted June 28, 2018 (edited) Really? SR works with QM and it's just GR that doesn't? Are you sure? Yes, but not because of distorted instruments (time dilation/length contraction). Well sort of it's because of TD and LC but not really because nobody is time dilated/ length contracted from their own point of view and their own point of view (in which observers in motion relative to them are time dilated and length contracted) are equally valid. Yes, SR is compatible with QFT it is called relativistic Quantum field Theory or RQFT, General Relativity and QM are not as compatible String theory makes them work together though, with a few anomalies. Not true! Doppler shift is what the redshift of distant galaxies is an example of. Redshift of distant galaxies is still caused by stuff moving through a strong gravitational field causing a change in the movement of the object stealing energy from the object making it appear as if moving more slowly or move more slowly if it loses energy from this gravitational field by escaping a strong one. Edited June 28, 2018 by VictorMedvil
DaveC426913 Posted June 28, 2018 Report Posted June 28, 2018 Here's what A-wal is saying: I asked for what you are saying. There is no point in someone else creating a scenario, and then you trying to describe whether it's right or wrong - that's how this thread got to where it is now.
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