Re: Not True oops. i m sure you meant to say relavy. that s what einstein s theory is called, and people who follow it are relavists. you know, like the general theory of relavy. rhymes with "gravy".
Re: Several No it doesn't. It just adds another component to consider when measuring a red-shift and determining what it represents. It isn't a matter of "one or the other". All the listed causes are real, and an object could exhibit a red-shift due to a combination of any or all of them at the same time. (Though velocity and time dilation really should be combined as one as relativistic red shift, since time dilation is a result of velocity. and I'd replace "distance" with Cosmological red-shift. ) The upshot is that your light sail will experience the Relativistic Red-shift due to its increased velocity with respect to the source, and varying degrees of the other red-shifts in addition. How much the other causes contribute in the way of extra red-shift depends on the actual conditions.
Hi all First point: Ryans statement is mathematically equivalent to my earlier statement(s) although (naturally) I prefer mine as being more physically meaningful. Second point: MacM's argument is based entirely on the assumption that Galilean relativity/Newtonian spacetime is the correct model. Of course if you make this assumption then relativity looks weird and magical. But this assumption is incorrect. The assumption is seen in statements such as ie of course there can be no limit to velocity unless something (like a brick wall) gets in the way. Of course if we accelerate for twice as long we end up with a relative velocity twice as large. In fact MacM earlier assumed even more explicitly that velocities can be added linearly. (Indeed he seems not to have acknowledged my correction and still assumes that velocities can always be added linearly.) The point is that in our (relativistic) Universe two objects can continually accelerate away from each other and never reach a relative velocity of c. The mathematics for this is all clear and self-consistent. We can work out what the rocket sees, what the earth sees or what a third party sees and these viewpoints all make sense to one another. However we can't do this in a way that preserves simple addition of velocities like MacM would like. If you want to know how do we know that we live in a relativistic Universe in which velocities don't add linearly then we can start a thread devoted to experimental tests of relativity S &/or G. But if you want to know why we live in a relativistic Universe rather than a sensible, comfortable, intuitive Newtonian one then you are unlikely to find an answer much more profound than "because we just do".
MacM you do not understand my arguement. It was along the lines of an answer produced by Tom Thus, if as you often assume, the principle of the invariance of the speed of light is invalid, my arguement holds and thus the maximum attainable velocity via this propulsion device is c after an infinite amount of time. Thus in the SR framework(redshift) and in the Newtonian framework, the maximum velocity is c. Now you have just screwed yourself. Within the SR framework, c is an upper limit to the velocity a particle may maintain by this direct effect, since of the 2 macroscopically manifested forces (gravity and electromagnetism), carriers of the EM force are photons, which by definition travel at c. Thus forces fealt due to the exchange of photons fundementally limit the the speed of massive bodies subject to this force. Since propulsion devices such as rockets, solar sails etc are propelled due to electromagnetic interactions, c is the maximal possible velocity in both classical theory and Special relativity due to electromagnetic interactions. If you cannot understand this MacM, I will see if I can get my 13 year old cousin to give you an interpretation.
Good Responses Martin B, Your responses are well thought out and courtious. They don't have to be but that is a more productive way of discourse. Rather than respond to each of your points let me summarize. You (and others) make an incorrect assumption about what I believe about Relativity. I know what it says and what it means. I am certainly no math expert in the field but I can work the algebraic portions at least. The point you seem to miss is that knowing this and looking around I see substantial indication that the Relavistic view is simply incorrect. That there are sound scientific alternative explanations for observations upon which Relativity is based and tested. Given those alternatives, which have physically logical components, compared to Relativity which is purely a mathematical concept and upon which many things such as the v=c limit on velocity which has not been tested, I opt for the newer views. James R., Thanks for the link. I will read it in detail but my preliminary reaction is that it is all but useless. This may be seen from the first paragraph. ************************************************* The Relativistic Rocket The theory of relativity sets a severe limit to our ability to explore the galaxy in space ships. As an object approaches the speed of light, more and more energy is needed to accelerate it further. To reach the speed of light an infinite amount of energy would be required. It seems that the speed of light is an absolute barrier which cannot be reached or surpassed by massive objects. *************************************************** [quote from above]As an object approaches the speed of light, more and more energy is needed to accelerate it further. To reach the speed of light an infinite amount of energy would be required. [unquote] ANS: The problem here is that the paper is based in the first instance in the acceptance and belief of the principles of Relativity and then they set about using Relavistic math to prove Relativity. There simply is no evidence to support the conclusion that a rocket will subject its thrust system to infinite mass and require infinite energy when the fuel, engine and rocket load are all at rest to one another at all times. This is a presumptive case, as most are, which requires that the imposed limit be caused by an observer and not the physics of the independant inertial system. Secondly even if that were true and it clearly is not, if the rocket becomes infinite so does the fuel and the rejected mass producing the thrust. We need not veer of course here with arguements about chemistry of the fuel not having the energy to push the infinite mass out of the rocket. These are not appropriate details to address the core issue. There may be more in the math section of this paper but I seriously have my doubts, in which case no velocity limit has been imposed by physics, it has been presumed and supported by math which applies to relavistic velocites between the load and the energy source (Which the solar sail qualifies for). I accept the relavistic limit between energy and load (But for different reasons, same observation). I do not accept the limit where there is no relavistic velocity in the independant inertial physics system.
MacM If you understand SR only on simple geometrical arguements, how can you possibly understand what a quantum red shift is and form an opinion of it?
MacM: The equations for the relativistic rocket are derived from simple considerations such as conservation of momentum. If you dispute the conclusions, you're disputing the whole of relativity. Yes, the derivation assumes relativity is true. That assumption is eminently reasonable, given that relativity is supported by innumerable experiments. In essence, you are saying that although you have not followed the derivation, you still dispute the conclusions reached. That is not a statement of science, but a statement of faith. If you think the explanation is wrong, you should be able to clearly point out why it is wrong. You say: <i>...I see substantial indication that the Relavistic view is simply incorrect. That there are sound scientific alternative explanations for observations upon which Relativity is based and tested.</i> So far, in your time at this site, you have not supplied a single "sound scientific alternative explanation" of anything. Perhaps now is the time to start. Go ahead.
Again I say Trying to change the whole of phyics without picking up a pen. You cannot say relativity is wrong simply because you disagree with it or it goes against you intuition. That's why it took so long to be found. SR can be derived with simple mathematics and few axioms, so why did it take so long to be discovered. Becasue it has profound implications for the way we view our world, which wee little minds cannot grasp. So they continue to suck at the nipple of mother Newton.
responses If you wish to present any evidence that contradicts relativity that would be welcome. This thread does not do that - it is based on an a priori rejection of a relativistic result, based on what could best be described as 'physical intuition'. Again such explanations are always welcomed. The best that can be said for anything presented on this forum however is that it 'requires further development and testing' ie it is not yet able to be considered an alternative. Outside this forum I am also unaware of any theory which replicates the experimentally verified predictions of relativity yet produces distinguishable predictions. I hate to harp on a theme, but here we have it again - solely because it does not conform to your ideas about the Universe, you imply that relativity is not "physically logical". I can assure you that it certainly is that. Relativity is a physical theory which describes physical quantities and makes physically verifiable predictions. We have never accelerated a macroscopic object to these speeds. On that basis, of course you have no reason to support your claim of "no relative speed limit" above the prediction of relativity. Both are purely thought experiments. We have however accelerated small particles to near these speeds - and relativity has been verified. We observe cosmic rays as well at these speeds and again relativity has been verified.
God help us if we start discussing quantum mechanics and probabilty waves... No one can help us when we start discussing relativistic quantum mechanics. OOPS, sorry we won't discuss that, not all have the required math, so we will keep debating this century old theory.
Right On ryans, I don't need to interprete the data I just read what the researchers say in the summary. It is there words no mine.
Again you fail to analyse my response correctly. It was in response to the question put forward and on the basis of the arguements previously used. 1. I stated that it will travel at c in the limit as t approaches infinity, i.e. never. 2. Even if the spedd of light is not constant for inertial observers in different frames of reference, as you might claim, the limit on the velocity of this propulsion system is still c, as time approaches infinity. You read the parts that support your arguement and forget the rest, typical of psuedo-science.
Re: Paritally Correct This only means that the object showing the red shift just might have a smaller velocity relative to us than originally calculated by assuming that all, or most, of the red shift was due to the object's velocity. IOW, the object may be moving away from us more slowly than previously thought. It does not mean that the part of the red-shift due to velocity has decreased while the velocity has remained unchanged. As such, it has no bearing on your original question. Here we already know the relative velocity between sail and light source(and are not trying to calculate it from the red-shift), and the Relativistic red-shift would be the minimum amount of red-shift that the sail would experience, with the other factors adding to it.
Data To All: Here is the type of information I generally refer to. He concludes with a very appropriate point which I thinkI must agree with. "If I can't prove you wrong then I am wrong" and frankly that is stagnant science. I really would be interested to see yur responses to this material. This is not an isolated case there are tons of such papers and yes I do try to determine if that are bonfide science. Some are not but many are and the fact is some comes from impressive institutions involved in such research. But you and just about every MSB participant like to quote Einstein but reject any alternative regardless of source. http://www2.rideau.net/gaasbeek/spap5.html This one deals with two flaws in SR testing and conclusions.
Switched Arguements ryans, I can understand people make slips and know better. I am sure that is the case here but you seem to prefer to hide that fact and try to associate your post by reposting Toms answer. The following is my objection to your post.
