Vmedvil2 Posted June 29, 2018 Report Share Posted June 29, 2018 (edited) Well, forgive me, V How about the phenomenon of a horn blowing on a truck that is moving toward/away from you changing pitch here on earth? Does dark energy cause that? Gravity? That causes a Vibration in the air which is actually a change in the movement of the molecules and atoms in the air besides that of temperature by the sound wave's Energy or Force, actually electromagnetism causes that as the charge and magnetism of the matter causes change in movement as they repeal each other or attract after the ripple of Pressure hits them which is the sound wave. Edited June 29, 2018 by VictorMedvil Link to comment Share on other sites More sharing options...
A-wal Posted June 29, 2018 Report Share Posted June 29, 2018 It is causes by Dark Energy, galaxy's redshift which is still a function of the Energy-Stress Tensor meaning gravity, there are two types of redshift Gravitational by gravity's pull and Dark Energy's Redshift.How is dark energy (basically shorthand for 'How come redshift?') a function of gravity? It's the supposed acceleration of the supposed expansion of the universe, how's that caused by gravitational attraction? Link to comment Share on other sites More sharing options...
Moronium Posted June 29, 2018 Report Share Posted June 29, 2018 (edited) That causes a Vibration in the air which is actually a change in the movement of the molecules and atoms in the air besides that of temperature by the sound wave's Energy or Force, actually electromagnetism causes that as the charge and magnetism of the matter causes change in movement as they repeal each other or attract after the ripple of Pressure hits them which is the sound wave. So the motion of the truck relative to the listener has nothing to do with it? Edited June 29, 2018 by Moronium Link to comment Share on other sites More sharing options...
Vmedvil2 Posted June 29, 2018 Report Share Posted June 29, 2018 (edited) How is dark energy (basically shorthand for 'How come redshift?') a function of gravity? It's the supposed acceleration of the supposed expansion of the universe, how's that caused by gravitational attraction? Well, as the universe expands the galaxies move away from each other and the time-space between them slowly expands, this causes a redshift due to the velocity of Space-time or the Universe's Fabric increasing in size which causes Dark Energy Redshift which is a lack of gravity on the Universe's Brane allowing it to expand at increasing rates aka accelerating expansion, anything to do with the movement of time-space or the universe's fabric is gravitational being the change in this fabric's structure. Edited June 29, 2018 by VictorMedvil Link to comment Share on other sites More sharing options...
Vmedvil2 Posted June 29, 2018 Report Share Posted June 29, 2018 (edited) So the motion of the truck relative to the listener has nothing to do with it? They do, but only in the time it will take for the wave to hit the object or objects in question. Edited June 29, 2018 by VictorMedvil Link to comment Share on other sites More sharing options...
Moronium Posted June 29, 2018 Report Share Posted June 29, 2018 You could probably keep yourself busy for a good long spell making all the necessary corrections at this wiki site, eh, Vic? https://en.wikipedia.org/wiki/Doppler_effect Link to comment Share on other sites More sharing options...
Vmedvil2 Posted June 29, 2018 Report Share Posted June 29, 2018 (edited) You could probably keep yourself busy for a good long spell making all the necessary corrections at this wiki site, eh, Vic? https://en.wikipedia.org/wiki/Doppler_effect Oh, your talking about a object in motion emitting the sound, yes this causes a shift in the frequency due to the motion of the object, due to the increased kinetic energy in one direction of the particles emitted and the decreased kinetic energy in another due to motion, and probably wikipedia is a descent source but there are much better. Edited June 29, 2018 by VictorMedvil Link to comment Share on other sites More sharing options...
A-wal Posted June 29, 2018 Report Share Posted June 29, 2018 (edited) Well, as the universe expands the galaxies move away from each other and the time-space between them slowly expands, this causes a redshift due to the velocity of Space-time or the Universe's Fabric increasing in size which causes Dark Energy Redshift which is a lack of gravity on the Universe's Brane allowing it to expand at increasing rates aka accelerating expansion, anything to do with the movement of time-space or the universe's fabric is gravitational being the change in this fabric's structure. That doesn't mean that the redshift of distant galaxies is actually caused by gravity. In the standard model it's being caused by dark energy and that's causing a lack of gravity in most areas of the universe as the galaxies move away from each other, so dark energy is having an effect on gravity but not being caused by it. Edited June 29, 2018 by A-wal Link to comment Share on other sites More sharing options...
Vmedvil2 Posted June 29, 2018 Report Share Posted June 29, 2018 (edited) That doesn't mean that the redshift of distant galaxies is actually caused by gravity. In the standard model it's being caused by dark energy and that's causing a lack of gravity in most areas of the universe as the galaxies move away from each other, so dark energy is having an effect on gravity but not being caused by it. Well, actually Dark Energy and Gravity are opposites, Dark Energy Expands Space-time and Normal Energy Compresses Space-time which is gravity, Gravity and Dark Energy can both cause Redshift from objects moving closer or farther away, while in motion as they pass through space-time effected by these. Edited June 29, 2018 by VictorMedvil Link to comment Share on other sites More sharing options...
Super Polymath Posted June 29, 2018 Report Share Posted June 29, 2018 Don't believe a word vmedvil says vee there is one person now you need to follow 006 Link to comment Share on other sites More sharing options...
OceanBreeze Posted June 29, 2018 Report Share Posted June 29, 2018 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. Good post A-wal, well done! Link to comment Share on other sites More sharing options...
Moronium Posted June 29, 2018 Report Share Posted June 29, 2018 (edited) Popeye, do you believe that there is any reliable way for two objects to measure the relative speed between each other? If so, do you agree with A-wal that B will measure, using physical, empirical (non-calculational) methods, his speed relative to C to be .756c? When I say "reliable," I just mean reliable in his frame. Forget all other frames. B has his own standards of both time and distance in his frame, which may be totally unique to him, and which nobody else in the universe may share with him, but that's not my concern here. Edited June 29, 2018 by Moronium Link to comment Share on other sites More sharing options...
Moronium Posted June 29, 2018 Report Share Posted June 29, 2018 (edited) In order to determine a speed, you need to know both the distance an object travelled and the time it took to do it, right? How would that be determined? If I'm object A and bounce a light beam off of an object , which is recedng from me, would that be sufficient? If I record the time it took for the beam to return, and then adjust that to factor in the time B moved away from me while the light beam was travelling, would that also be sufficient to inform me of the distance? If so, I would then know both the time and distance and could thereby derive the speed, is that right? But, it seems like, in order to factor in the distance B moved while the light was travelling, I would have to already know the distance. On the other hand, if I already know what the speed of light is, then I wouldn't need to know both time and distance--just one or the other, right? The time alone would be sufficient to also tell me the distance. How does that work? Edited June 29, 2018 by Moronium Link to comment Share on other sites More sharing options...
OceanBreeze Posted June 29, 2018 Report Share Posted June 29, 2018 Popeye, do you believe that there is any reliable way for two objects to measure the relative speed between each other? If so, do you agree with A-wal that B will measure, using physical, empirical (non-calculational) methods, his speed relative to C to be .756c? When I say "reliable," I just mean reliable in his frame. Forget all other frames. B has his own standards of both time and distance in his frame, which may be totally unique to him, and which nobody else in the universe may share with him, but that's not my concern here. Do I think it is possible? Yes, I do. Presently, using redshift we are able to determine the velocity of distant galaxies that are moving very close to the speed of light. I gave an example of this a bit further up-thread for Galaxy GN-z11: Currently the oldest and most distant known galaxy in the observable universe. It is also the most red-shifted object we have observed. GN-z11 has a spectroscopic redshift of z = 11.09, which corresponds to a proper distance of approximately 32 billion light-years (9.8 billion parsecs) Also, the equation for Relativistic Doppler Redshift is: [math]Z=\sqrt { \frac { 1+v/c }{ 1-v/c } } -1[/math] So, just plug the numbers in for Gn-z11 and you find that its recession velocity works out to 0.986c at the time the light we see was emitted. Its recession velocity today may be well over the velocity of light, assuming that galaxy GN-z11 still exists! So, yes to your second question as well. B should be able to reliably measure the velocity of C, with respect to B as 0.756c using redshift or some other method. For our purposes what does it matter what method is used? Let the aeronautical engineers work that out! Keep in mind that I am only stating my opinion here. Presently, the fastest spacecraft we have, still haven’t even reached 0.1% of the velocity of light, so opinions are really all we have to go on and mine is no better than that of anyone else. Link to comment Share on other sites More sharing options...
Moronium Posted June 29, 2018 Report Share Posted June 29, 2018 Do I think it is possible? Yes, I do. So, yes to your second question as well. Keep in mind that I am only stating my opinion here. Presently, the fastest spacecraft we have, still haven’t even reached 0.1% of the velocity of light, so opinions are really all we have to go on and mine is no better than that of anyone else. OK, thanks. I think your opinion is much better than Vic's, for what it's worth. He said there would be no redshift at all without gravity because gravity was the only thing that could cause a doppler shift, as I understood him. I don't buy that. Link to comment Share on other sites More sharing options...
Moronium Posted June 29, 2018 Report Share Posted June 29, 2018 (edited) For our purposes what does it matter what method is used? Let the aeronautical engineers work that out! Well, to me it kinda does. I'm trying to tie this all together. That's why I asked the question you answered here. I want to know if someone is measuring their speed by calculating it from some a priori assumption, or if it's actually backed up by empirical observation somehow. Because I'm trying to tie it all together, the method is also of interest to me, especially as it pertains to the speed of light. I just asked another question, which relates to that. What you be your answer to that, if you have one and don't mind revealing it. Edited June 29, 2018 by Moronium Link to comment Share on other sites More sharing options...
Moronium Posted June 29, 2018 Report Share Posted June 29, 2018 (edited) Because I'm trying to tie it all together, the method is also of interest to me, especially as it pertains to the speed of light. I just asked another question, which relates to that. What you be your answer to that, if you have one and don't mind revealing it. It might be easier to start with a case where there is no relative motion. If I see object B, off in the distance (how far I don't currently know) which is NOT moving relative to me, would this work? I bounce a light beam off of it, which returns to me. It takes two seconds for it to do that. Could I then confidently say that I now know its distance from me (i.e., 1 light second, which is approx. 186,000 miles)? Edited June 29, 2018 by Moronium Link to comment Share on other sites More sharing options...
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