Centripetal force, gravity, and relativity

BoJangles · Aug 5, 2008

1)  Could Centripetal force somehow be related to gravity? If you spun me in a giant centrifuge I would definitely feel a sense of gravity. In fact we can measure the force applied to my body spun in a centrifuge in g’s. As far as my body would be concerned they will feel like similar forces (gravity and centripetal force), seems like they are one and the same, jsut described in diffrent ways.2) Now if you spun an atomic clock in a centrifuge would it time dilate in rearguards to relativity, would it lose time in the classical sense.  I.e. would it experience time dilation as far as relativity is concerned? Has anyone done this?The reason I'm asking, is because it seems the proof for time dilation is atomic clocks. Could the effect seen with atomic clocks be somehow related to superficial changes in the sub atomic nature of the electron, or of how an atomic clock works, and not a real time affect?I suppose I'm probably fundamentally confused with the question, is time dilation a speed thing, a mass thing or a gravity thing in regards to relativity.Ps. I realise this post is very disjointed :/ <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

Mee_n_Mac · Aug 5, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>1)  Could Centripetal force somehow be related to gravity? If you spun me in a giant centrifuge I would definitely feel a sense of gravity. In fact we can measure the force applied to my body spun in a centrifuge in g’s. As far as my body would be concerned they will feel like similar forces (gravity and centripetal force), seems like they are one and the same, jsut described in diffrent ways. Posted by Manwh0re</DIV>The best answer I can give is .... maybe they are related.  What you're experiencing on the centrifuge is related to the property we call inertia.  Your body wants to remain going in a straight line but the centrifuge is forcing it to change direction. Not really any different than the seat pushing your back in a very quickly accelerating car.  Why mass has inertia and how mass experiences gravity may be two related phenomena, perhaps 2 faces of the same phenomena (like electric and magnetic fields) but right now I'm not aware this has been proven to be so.  Replying to: <DIV CLASS='Discussion_PostQuote'>2) Now if you spun an atomic clock in a centrifuge would it time dilate in rearguards to relativity, would it lose time in the classical sense.  I.e. would it experience time dilation as far as relativity is concerned? Has anyone done this?The reason I'm asking, is because it seems the proof for time dilation is atomic clocks. Could the effect seen with atomic clocks be somehow related to superficial changes in the sub atomic nature of the electron, or of how an atomic clock works, and not a real time affect?I suppose I'm probably fundamentally confused with the question, is time dilation a speed thing, a mass thing or a gravity thing in regards to relativity.Ps. I realise this post is very disjointed :/ Posted by Manwh0re</DIV>There is time dilation due to speed alone per Special Relativity.  You've probably heard of the twin "paradox". This phenomenon has been observed directly in particle accelerators as the particles produced by the collisions would normally decay in a very short time but have been observed for longer times due to their high (relativistic) speeds. General Relativity also says time runs differently in high gravitational fields vs low gravitational fields. This has been observed in atomic clocks sent by airplanes to different altitudes (and thus ever so slightly different gravity fields).  By the Equivalence Priniciple I would say that you also experience time dilation on your centrifuge or in a very quickly accelerating car.  But just a wee tiny bit. Accelerate hard, go fast and live longer ... that's my motto ! <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" /> <div class="Discussion_UserSignature"> -----------------------------------------------------Ask not what your Forum Software can do do on you,Ask it to, please for the love of all that's Holy, STOP ! </div>

derekmcd · Aug 6, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>1)  Could Centripetal force somehow be related to gravity? If you spun me in a giant centrifuge I would definitely feel a sense of gravity. In fact we can measure the force applied to my body spun in a centrifuge in g’s. As far as my body would be concerned they will feel like similar forces (gravity and centripetal force), seems like they are one and the same, jsut described in diffrent ways.2) Now if you spun an atomic clock in a centrifuge would it time dilate in rearguards to relativity, would it lose time in the classical sense.  I.e. would it experience time dilation as far as relativity is concerned? Has anyone done this?The reason I'm asking, is because it seems the proof for time dilation is atomic clocks. Could the effect seen with atomic clocks be somehow related to superficial changes in the sub atomic nature of the electron, or of how an atomic clock works, and not a real time affect?I suppose I'm probably fundamentally confused with the question, is time dilation a speed thing, a mass thing or a gravity thing in regards to relativity.Ps. I realise this post is very disjointed :/ Posted by Manwh0re</DIV>Anytime you find yourself asking, "does time dilation affect ______ ?".  The answer is always yes.   So yes, an atomic clock in a centrifuge would experience time dilation.  You can see this in action with the decay rates of particles in particle accelerators.Time dilation is a velocity thing and through the equivalence principle you have a velocity standing on earth which slows your clock down compared to someone in a lesser gravity well.  So, time dilation cal also be a gravity thing, but it is still related to velocity and Special Relativity.  <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

BoJangles · Aug 6, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Anytime you find yourself asking, "does time dilation affect ______ ?".  The answer is always yes.   So yes, an atomic clock in a centrifuge would experience time dilation.  You can see this in action with the decay rates of particles in particle accelerators.Time dilation is a velocity thing and through the equivalence principle you have a velocity standing on earth which slows your clock down compared to someone in a lesser gravity well.  So, time dilation cal also be a gravity thing, but it is still related to velocity and Special Relativity.  Posted by derekmcd</DIV> Ok thanks guys

<div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

vandivx · Aug 9, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Time dilation is a velocity thing and through the equivalence principle you have a velocity standing on earth which slows your clock down compared to someone in a lesser gravity well.  So, time dilation cal also be a gravity thing, but it is still related to velocity and Special Relativity.  Posted by derekmcd</DIV>the principle you mention means the equivalence of gravitation and acceleration, not gravitation and velocity (for nitpickers - equivalence of gravitational and inertial forces such as those arising in a gravitational field and accelerated reference frame or in other words the equivalence of gravitational and inertial mass) while acceleration is changing velocity, it is not in my books quite the same as velocity given that the former is accompanied by force while the latter is not   <div class="Discussion_UserSignature"> </div>

DrRocket · Aug 9, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>1)  Could Centripetal force somehow be related to gravity? If you spun me in a giant centrifuge I would definitely feel a sense of gravity. In fact we can measure the force applied to my body spun in a centrifuge in g’s. As far as my body would be concerned they will feel like similar forces (gravity and centripetal force), seems like they are one and the same, jsut described in diffrent ways.2) Now if you spun an atomic clock in a centrifuge would it time dilate in rearguards to relativity, would it lose time in the classical sense.  I.e. would it experience time dilation as far as relativity is concerned? Has anyone done this?The reason I'm asking, is because it seems the proof for time dilation is atomic clocks. Could the effect seen with atomic clocks be somehow related to superficial changes in the sub atomic nature of the electron, or of how an atomic clock works, and not a real time affect?I suppose I'm probably fundamentally confused with the question, is time dilation a speed thing, a mass thing or a gravity thing in regards to relativity.Ps. I realise this post is very disjointed :/ Posted by Manwh0re</DIV>In special relativity time dilation is the result of relative velocity.  But special relativity only covers cases in which gravity and acceleration can be neglected.In general relativity space-time is curved by the presence of mass.  This curvature in space-time results in the "slowing down" of time in regions of high curvature, or equivalently high gravitational fields.  This effect can actually be measured in terms of changes in time with elevation near the surface of the earth -- see a link I posted for you in another thread.So both speed and gravity can affect time.  And mass is obviously related to gravity so there is an effect of mass in that sense.   <div class="Discussion_UserSignature"> </div>

kg · Aug 9, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>In special relativity time dilation is the result of relative velocity.  But special relativity only covers cases in which gravity and acceleration can be neglected.In general relativity space-time is curved by the presence of mass.  This curvature in space-time results in the "slowing down" of time in regions of high curvature, or equivalently high gravitational fields.  This effect can actually be measured in terms of changes in time with elevation near the surface of the earth -- see a link I posted for you in another thread.So both speed and gravity can affect time.  And mass is obviously related to gravity so there is an effect of mass in that sense.  Posted by DrRocket</DIV> I think the question being asked is... an object in a centrifuge experiences something similar to a stronger gravitational field.  However the object isnt in a stronger gravitational field.  So if you spin this object up to say 1000gs will it experience the "slowing down" of time that it would if it were on a planet that was massive enough to give you 1000gs on its surface?

vandivx · Aug 10, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I think the question being asked is... an object in a centrifuge experiences something similar to a stronger gravitational field.  However the object isnt in a stronger gravitational field.  So if you spin this object up to say 1000gs will it experience the "slowing down" of time that it would if it were on a planet that was massive enough to give you 1000gs on its surface?  Posted by kg</DIV> yes, precisely that would happen, that's what the equivalence principle is about - it is 'exactly' the same being in a given gravitational field or in a centrifuge that supplied the same acceleration, time dilation will be the same in both cases if the acceleration will be the same in both cases regardles if it is due to motional acceleration or gravitational acceleration  ----- I put the word 'exactly' into qualifying brackets for the nitpickers: there is some difference in 'artificial' gravitational field of the centrifuge from the real gravitational field (so called tidal effects by which one might tell real gravitation from that generated by a centrifuge) but that is nothing that would affect time dilation <div class="Discussion_UserSignature"> </div>

vandivx · Aug 12, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> There is time dilation due to speed alone per Special Relativity.  You've probably heard of the twin "paradox". Posted by mee_n_mac</DIV> I am wondering whether you realize or believe that 'time dilation due to speed alone' implies absolute motion (absolute space) if what we are talking about is time dilation with lasting effects, such as that in twin 'paradox' thought experiment  in arguments around differential twin aging it is often argued that the twin that went on the trip was 'really moving' because he was the one who accelerated... but relativity of motion means there is no such thing as 'real motion' or 'really moving', it is all relative motion - and that implies that linear motion (speed) should only lead to apparent time dilation by relativity books, that is one without lasting effects - time dilation should be relative and the twins shouldn't age differently because of this, opponents of absolute space (defenders of relativity) argue that the real timeshift between the twins is due to either acceleration (at the begining and middle of the journey during turnaround - but that had been refuted, acceleration by itself cannot account for all the time difference btw twins) or else they say its due to (abrupt) shifting of the reference frame during turnaround in the middle of the journey relative to the 'stay at home twin' (this latter attribution smacks almost of unreality, that is magic)  I don't really want to start twin 'paradox' discussion here but just to point out that time dilation with accumulated lasting effects due to linear motion can be a controversial thing also and I thought to bring that up seeing how carefully you hedged your position regarding the equivalence principle personally I believe in real, that is absolute space because time dilation which is observed experimentally in velocity experiments is real (as opposed to relative) and is due to velocity (such as in that 'twin' thought experiment)of course I realize that absolute space is incompatible with relativity theories which are the bedrock of twenties century physics and that if I am right something will have to give in that bedrock (bedrocks can and do shift when their base is not firm)  "Could Centripetal force somehow be related to gravity? " Replying to: <DIV CLASS='Discussion_PostQuote'>The best answer I can give is .... maybe they are related.  ... Posted by mee_n_mac</DIV> here on the other hand, I would say not maybe but they are related (motional acceleration and gravity) in all respects, period, one of the aspects of this relation being time dilation  any doubts on this count simply reflect the fact that nobody knows how inertia works (and GR's curved space is not satisfactory physical explanation if only because it says nothing about inertia and any gravitation theory that doesn't explain inertia is not complete in my books and therefore not correct), that is we don't have any acceptable explanation of the phenomenon of inertia  and so many scientists (would be and tenured ones) hedge their position regarding the equivalence principle but common sense tells us (I dare to claim) that related they are, that inertial and gravitational mass are in fact the same (quite besides the experimental agreement) except we don't yet see how (physical explanation of inertia that could bring light into the matter is lacking)  on the same note, I'd say that speed (in absolute space so that it is 'real speed'), mass (through its inertial effects due to acceleration - mass is a measure of inertia) and gravitation (which is also acceleration by equivalence principle but you get time dilation only when it is 'static acceleration' such as when you sit in your chair on the Earth surface*, not (I think) when it is dynamic, such as in a freefall in grav. field - when you fall off your chair, not sure if this latter is experimentally confirmed or not)*[as with most things there are exceptions - you would get time dilation if your chair were located in some chamber in the middle of Earth where you would have no acceleration towards chamber walls and therefore to seat of the chair but time dilation would be present all the same - your time would pass slower there than if you were located in a region of free space away from any planet or star] these three all have one thing in common which is responsible for time dilation, it is usually that way in physics, nature does not 'invent' different causes for the same effects (Occam's Razor?) except nobody has yet identified what that common ground or principle is the original thread poster should know that he is touching on yet unsettled part of physics which, while being well developped mathematically, is sorely lacking when it comes to the real physical explanations and so to certainty, which in the last instance requires some physical explanation, some picture or model of the physical phenomena at hand, today's physics is singularly poor in that regard, so much so that physicists do not anymore deserve to be called physicists in my books if that means explaining nature in physical terms as opposed to mathematical (quantitative) terms, I am not saying it is not valuable description of nature but nevertheless it cannot supply understanding which is what the real physics should be about <div class="Discussion_UserSignature"> </div>

DrRocket · Aug 12, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> I am wondering whether you realize or believe that 'time dilation due to speed alone' implies absolute motion (absolute space) if what we are talking about is time dilation with lasting effects, such as that in twin 'paradox' thought experiment  in arguments around differential twin aging it is often argued that the twin that went on the trip was 'really moving' because he was the one who accelerated... but relativity of motion means there is no such thing as 'real motion' or 'really moving', it is all relative motion - and that implies that linear motion (speed) should only lead to apparent time dilation by relativity books, that is one without lasting effects - time dilation should be relative and the twins shouldn't age differently because of this, opponents of absolute space (defenders of relativity) argue that the real timeshift between the twins is due to either acceleration (at the begining and middle of the journey during turnaround - but that had been refuted, acceleration by itself cannot account for all the time difference btw twins) or else they say its due to (abrupt) shifting of the reference frame during turnaround in the middle of the journey relative to the 'stay at home twin' (this latter attribution smacks almost of unreality, that is magic)  ...Posted by vandivx</DIV>It is really not magic.  A completely rigorous resolution of the twin paradox can be accomplished through the use of general relativity.  It shows that the twin who goes away and comes back does in fact age less.  This has been demonstrated experimentally by flying one atomic clock on an aircraft and comparing it to one that has remained on the ground.General relativity has been thoroughly tested in experiments and has been found to pass with flying colors.  The only known issues involve situations in which quantum effects are important.  There we have a problem since quantum theory and general relativity are not compatible.  At least one of them needs to be revised to cover such situations.http://en.wikipedia.org/wiki/Tests_of_general_relativity <div class="Discussion_UserSignature"> </div>

vandivx · Aug 12, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>It is really not magic.  A completely rigorous resolution of the twin paradox can be accomplished through the use of general relativity.  It shows that the twin who goes away and comes back does in fact age less.  This has been demonstrated experimentally by flying one atomic clock on an aircraft and comparing it to one that has remained on the ground.General relativity has been thoroughly tested in experiments and has been found to pass with flying colors.  The only known issues involve situations in which quantum effects are important.  There we have a problem since quantum theory and general relativity are not compatible.  At least one of them needs to be revised to cover such situations.http://en.wikipedia.org/wiki/Tests_of_general_relativity Posted by DrRocket</DIV> we both know that magic doesn't happen of course, I also have no dispute with the difference in passing of time between the twins which I believe is true, experiments confirm it, what I don't agree with is the interpretation of what the time loss is due to in conventional explanations of the twin thought experiment because people try to make it so that time dilation doesn't happen during uniform velocity part of the trip  you have yourself said velocity (was it speed? but that is no matter) is one of the states of matter that leads to time dilation with which I agree, what I am saying then is that that implies existence of absolute space, now because that is not acceptable to offical physics view, people either don't want to acknowledge that or else they try to make it so that all the differential aging happens not during velocity part of the trip but during the acceleration part or during the reference frame change at the turning pointso what I am saying is that if your calculations (employing GR) imply that traveling twin ages less besides other parts of the journey also during the time he coasted along at uniform speed then I am claiming that that would imply existence of absolute space - that is speed is no longer relative which goes against relativity principle no less so I have no dispute that calculations are somehow done wrongly, as you say it all adds up when calculated properly the part of the trip that happens at uniform speed can be made arbitrarily large making the acceleration parts of the trip negligible, also there is a way (which I invented) to arrange the thought experiment so that the acceleration and even the change of reference frame part of the trip can be eliminated (cancelled out) - both twins start on the journey each in his own rocket, they accelerate side by side to achieve traveling speed and coast together for a bit and then one of them decides to turn back and returns home (where he waits for his brother to return) and the other one continues to travels at that coasting speed for some years before he also decides to turn around and return homeupon return, this twin that coasted years longer at constant speed will have aged less and because both twins have underwent the same amounts of acceleration in all respects including the change of reference frame, it can be taken out of the calculation altogether, right? [any time dilation that happened during those parts of the trip will affect both twins the same amount] and we are left with just the time dilation due to coasting at uniform velocity which makes for simple calculation and if the longer traveling twin is now younger, I say that means that space has to be absolute, that is speed is absolute same as acceleration is and relativity of motion is not true, because of time dilation, one can tell who was really moving through space and who was not my position is that time dilation during uniform motion happens and so space is absolute, Einstein notwithstanding          <div class="Discussion_UserSignature"> </div>

DrRocket · Aug 12, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>we both know that magic doesn't happen of course, I also have no dispute with the difference in passing of time between the twins which I believe is true, experiments confirm it, what I don't agree with is the interpretation of what the time loss is due to in conventional explanations of the twin thought experiment because people try to make it so that time dilation doesn't happen during uniform velocity part of the trip  you have yourself said velocity (was it speed? but that is no matter) is one of the states of matter that leads to time dilation with which I agree, what I am saying then is that that implies existence of absolute space, now because that is not acceptable to offical physics view, people either don't want to acknowledge that or else they try to make it so that all the differential aging happens not during velocity part of the trip but during the acceleration part or during the reference frame change at the turning pointso what I am saying is that if your calculations (employing GR) imply that traveling twin ages less besides other parts of the journey also during the time he coasted along at uniform speed then I am claiming that that would imply existence of absolute space - that is speed is no longer relative which goes against relativity principle no less so I have no dispute that calculations are somehow done wrongly, as you say it all adds up when calculated properly the part of the trip that happens at uniform speed can be made arbitrarily large making the acceleration parts of the trip negligible, also there is a way (which I invented) to arrange the thought experiment so that the acceleration and even the change of reference frame part of the trip can be eliminated (cancelled out) - both twins start on the journey each in his own rocket, they accelerate side by side to achieve traveling speed and coast together for a bit and then one of them decides to turn back and returns home (where he waits for his brother to return) and the other one continues to travels at that coasting speed for some years before he also decides to turn around and return homeupon return, this twin that coasted years longer at constant speed will have aged less and because both twins have underwent the same amounts of acceleration in all respects including the change of reference frame, it can be taken out of the calculation altogether, right? [any time dilation that happened during those parts of the trip will affect both twins the same amount] and we are left with just the time dilation due to coasting at uniform velocity which makes for simple calculation and if the longer traveling twin is now younger, I say that means that space has to be absolute, that is speed is absolute same as acceleration is and relativity of motion is not true, because of time dilation, one can tell who was really moving through space and who was not my position is that time dilation during uniform motion happens and so space is absolute, Einstein notwithstanding          Posted by vandivx</DIV>You have part of the story correct, but have badly misconstrued the basic physics.  The difference aging is due almost entirely to the time spent "coasting" at high velocity.  What the acceleration does is point out that only one reference frame in the problem can be handled as an inertial reference frame and that is the frame attached to the earth.  But the conclusion that there is such a thing as absolute rest has been evaluated and found incorrect numerous times, and verified by all experimental data that has been found to date.If you want to see the twin paradox and other "paradoxes" so special relativity explained, I recommend either Introduction to Special Relativity by Wolfgang Rindler or The Road to Reality by Roger Penrose.  You will find a good discussion of the twin paradox in either book. <div class="Discussion_UserSignature"> </div>

vandivx · Aug 13, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>You have part of the story correct, but have badly misconstrued the basic physics.  The difference aging is due almost entirely to the time spent "coasting" at high velocity.  What the acceleration does is point out that only one reference frame in the problem can be handled as an inertial reference frame and that is the frame attached to the earth.  But the conclusion that there is such a thing as absolute rest has been evaluated and found incorrect numerous times, and verified by all experimental data that has been found to date. Posted by DrRocket</DIV> I have no idea where you see 'badly misconstrued basic physics', perhaps instead of giving me a 'stick' you could first explain yourself, maybe you are not used to deal with anything potentially new in physics and anything of that nature you automatically label as "badly misconstrued basic physics", it wouldn't be the first time that physicists would have been mistaken even for centuries on end and then they would have corrected themselves and I dare say time will repeat itself with absolute space and rest of course some wouldn't ever admit to any correction but death would ultimately eliminate their bitter and blind opposition, hence that saying about old physicists having to die before new ideas can be accepted, objective approach and openness to new ideas is very easy to proclaim in theory but difficult to uphold when new ideas actually confront one, that's what we talked about in that recent thread about unrecognized geniuses and I found it laughable and useless to try to fight that false confidence people (in particular it was you and derekmcdin last two posts on that thread) had about the recognition and ready acceptance of new ideas should such arise in our times, people seem to imagine that new ideas will always be in harmony with preexisting ones and would only extend current physics... they arrogantly assume their discipline can't be wrong in these 'modern' times but what is modern is relative, physicists always were too much confident in whatever physics they knew at the time and dismissed past mistakes of science as something that wouldn't happen to them in their 'modern' times  --------------on the other hand I realize that such claim as I put forth implies fundamental changes in physics (in no less than the cherrished theory of special relativity) and I can't expect serious scientists who see far ahead and understand the deep implications such claim implies to simply go along, in the face of such fundamental changes many will even burry their head in sand and maintain status quo regardless of challenge staring in their faces and maintain that 'king has new clothes' on him   I get the impression you keep misreading my posts, it is also my opinion that "The difference aging is due almost entirely to the time spent "coasting" at high velocity" as you state, that is because as I wrote above, one can make coasting part of the trip dominant only reason I talked about acceleration and reference frame change parts of the trip is because those parts are often  made responsible for most or even all of the time dilation by people (typically on internet but among those are often professional physicists) who see the inacceptability for physics as we currently know it of absolute space that the time dilation at constant velocity implies and they try to evade the issue that way, my own position on the matter agrees exactly with what you said above - that "the difference aging is due almost entirely to the time spent "coasting" at high velocity" "The conclusion that there is such a thing as absolute rest has been evaluated and found incorrect numerous times, and verified by all experimental data that has been found to date." that's correct as far as it goes, however the nature of the subject itself (absolute space and rest in it) is such that its detection or determination is open to a mistake commonly called 'shooting down the straw man', that is one can only claim that one didn't find in his experiments confirmation of certain preconceived ideas of his own regarding absolute space but the thing with absolute space is that it is not as simple to prove its existence as it is to prove that a murder happened when a dead body is found with knife in its back as positive evidence, some things in physics are not open to such positive finds that one cannot doubt the findings Michelson & Morley did precisely just that (knock down straw man) as one example, in effect what they did was to put ultimatum to nature so to speak - they said if ether exists, such and such should be found in their experiment (interference) and when it wasn't found, it was taken as proof that ether (absolute space and motion or rest in it) doesn't exist (it was likely later interpretation by others of this experiment but that doesn't change the role this experiment had in the history of physics), simply put it could be likened to a claim that ether consists of wheels and gears and because one doesn't see such when he looks around oneself, the false conclusion is that ether doesn't exist, with gears and wheels serving in this case as straw man what an arrogant way this implies towards nature - saying that if my ideas how I think the nature should behave don't conform to my findings, then too bad for nature I am saying that experiments which confirm time dilation due to uniform velocity directly imply that uniform motion is not relative and it is too bad for experiments that were done so far which allegedly disproved its existence, point is are we going to bet the stalling of progress in physics and put our trust in experiments which are subject to complex interpretations which may not be correct after all or are we going to seize the opprotunity that offers itself here, new starting points of great theories in physics were started off in past on much less firm ground, on mere indications or even a hunch that something may not be right... but it usually was some lonely genius that seized the opportunity while the scientific community were totally blind to the initial clue that sparked it all off, that's what the case here if you asked me if absolute space did not exist then it wouldn't (shouldn't) matter which twin set on the journey and accelerated, if we took aside some time dilation due to acceleration, then if uniform motion were truly relative, one could view the stay at home twin as moving while the other one was at rest in his rocket (coasting along at traveling speed but in his reference frame taken as base he would be at rest) and time dilation would be only an apparent effect resulting from viewing the other twin from another reference frame and both could say of each other that the clock of his counterpart ran slower - BUT if the motion were really relative, then there should be no aging difference due to uniform velocity when they came back together at some point and compared their clocks BUT we both know experiments actually performed say otherwise - there is real time difference accumulated due to uniform motion - the twin that aged less was really moving and it would be false to take symmetric, that is relativistic view of affairs, the twin that accelerated was really moving while the one who didn't accelerate was at rest - the motion and rest of course reffering to absolute space the experiments DO confirm that time dilation with lasting effect occurs due to motion at uniform velocity and that naturally forces the inescapable conclusion that in that case space has to be real, that is absolute, real effects resulting from the uniform motion beg that the space in which that motion occurs is real  I see the experiments confirming the time dilation as convincing (they come from various indirect and even direct testing as well as being upheld in various other experiments of which time dilation is not the subject but is the attending and perhaps even counted on effect, like in particle accelerators experiments) while I see those experiments that claim that absolute space doesn't exist as the straw men of physics, the way I see it the absolute space is the future of physics, it is often that which we don't want to see that we end up not seeing and while scientists often realize that themselves, still they fall victims to it time after time, thing is that while experiments can be fairly decisive when it comes to raw data coming from them, many times these results can be subject to various interpretation as experimentalists themselves know only too well    <div class="Discussion_UserSignature"> </div>

DrRocket · Aug 13, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I have no idea where you see 'badly misconstrued basic physics', perhaps instead of giving me a 'stick' you could first explain yourself, maybe you are not used to deal with anything potentially new in physics and anything of that nature you automatically label as "badly misconstrued basic physics", it wouldn't be the first time that physicists would have been mistaken even for centuries on end and then they would have corrected themselves and I dare say time will repeat itself with absolute space and rest of course some wouldn't ever admit to any correction but death would ultimately eliminate their bitter and blind opposition, hence that saying about old physicists having to die before new ideas can be accepted, objective approach and openness to new ideas is very easy to proclaim in theory but difficult to uphold when new ideas actually confront one, that's what we talked about in that recent thread about unrecognized geniuses and I found it laughable and useless to try to fight that false confidence people (in particular it was you and derekmcdin last two posts on that thread) had about the recognition and ready acceptance of new ideas should such arise in our times, people seem to imagine that new ideas will always be in harmony with preexisting ones and would only extend current physics... they arrogantly assume their discipline can't be wrong in these 'modern' times but what is modern is relative, physicists always were too much confident in whatever physics they knew at the time and dismissed past mistakes of science as something that wouldn't happen to them in their 'modern' times  --------------on the other hand I realize that such claim as I put forth implies fundamental changes in physics (in no less than the cherrished theory of special relativity) and I can't expect serious scientists who see far ahead and understand the deep implications such claim implies to simply go along, in the face of such fundamental changes many will even burry their head in sand and maintain status quo regardless of challenge staring in their faces and maintain that 'king has new clothes' on him   I get the impression you keep misreading my posts, it is also my opinion that "The difference aging is due almost entirely to the time spent "coasting" at high velocity" as you state, that is because as I wrote above, one can make coasting part of the trip dominant only reason I talked about acceleration and reference frame change parts of the trip is because those parts are often  made responsible for most or even all of the time dilation by people (typically on internet but among those are often professional physicists) who see the inacceptability for physics as we currently know it of absolute space that the time dilation at constant velocity implies and they try to evade the issue that way, my own position on the matter agrees exactly with what you said above - that "the difference aging is due almost entirely to the time spent "coasting" at high velocity" "The conclusion that there is such a thing as absolute rest has been evaluated and found incorrect numerous times, and verified by all experimental data that has been found to date." that's correct as far as it goes, however the nature of the subject itself (absolute space and rest in it) is such that its detection or determination is open to a mistake commonly called 'shooting down the straw man', that is one can only claim that one didn't find in his experiments confirmation of certain preconceived ideas of his own regarding absolute space but the thing with absolute space is that it is not as simple to prove its existence as it is to prove that a murder happened when a dead body is found with knife in its back as positive evidence, some things in physics are not open to such positive finds that one cannot doubt the findings Michelson & Morley did precisely just that (knock down straw man) as one example, in effect what they did was to put ultimatum to nature so to speak - they said if ether exists, such and such should be found in their experiment (interference) and when it wasn't found, it was taken as proof that ether (absolute space and motion or rest in it) doesn't exist (it was likely later interpretation by others of this experiment but that doesn't change the role this experiment had in the history of physics), simply put it could be likened to a claim that ether consists of wheels and gears and because one doesn't see such when he looks around oneself, the false conclusion is that ether doesn't exist, with gears and wheels serving in this case as straw man what an arrogant way this implies towards nature - saying that if my ideas how I think the nature should behave don't conform to my findings, then too bad for nature I am saying that experiments which confirm time dilation due to uniform velocity directly imply that uniform motion is not relative and it is too bad for experiments that were done so far which allegedly disproved its existence, point is are we going to bet the stalling of progress in physics and put our trust in experiments which are subject to complex interpretations which may not be correct after all or are we going to seize the opprotunity that offers itself here, new starting points of great theories in physics were started off in past on much less firm ground, on mere indications or even a hunch that something may not be right... but it usually was some lonely genius that seized the opportunity while the scientific community were totally blind to the initial clue that sparked it all off, that's what the case here if you asked me if absolute space did not exist then it wouldn't (shouldn't) matter which twin set on the journey and accelerated, if we took aside some time dilation due to acceleration, then if uniform motion were truly relative, one could view the stay at home twin as moving while the other one was at rest in his rocket (coasting along at traveling speed but in his reference frame taken as base he would be at rest) and time dilation would be only an apparent effect resulting from viewing the other twin from another reference frame and both could say of each other that the clock of his counterpart ran slower - BUT if the motion were really relative, then there should be no aging difference due to uniform velocity when they came back together at some point and compared their clocks BUT we both know experiments actually performed say otherwise - there is real time difference accumulated due to uniform motion - the twin that aged less was really moving and it would be false to take symmetric, that is relativistic view of affairs, the twin that accelerated was really moving while the one who didn't accelerate was at rest - the motion and rest of course reffering to absolute space the experiments DO confirm that time dilation with lasting effect occurs due to motion at uniform velocity and that naturally forces the inescapable conclusion that in that case space has to be real, that is absolute, real effects resulting from the uniform motion beg that the space in which that motion occurs is real  I see the experiments confirming the time dilation as convincing (they come from various indirect and even direct testing as well as being upheld in various other experiments of which time dilation is not the subject but is the attending and perhaps even counted on effect, like in particle accelerators experiments) while I see those experiments that claim that absolute space doesn't exist as the straw men of physics, the way I see it the absolute space is the future of physics, it is often that which we don't want to see that we end up not seeing and while scientists often realize that themselves, still they fall victims to it time after time, thing is that while experiments can be fairly decisive when it comes to raw data coming from them, many times these results can be subject to various interpretation as experimentalists themselves know only too well    Posted by vandivx</DIV>I did explain the physics.  There is only one reference frame in the so-called paradox that can be considered to be inertial and one must have an inertial reference frame to apply special relativity.  You can also view the problem in the framework of general relativity which is set up to consider acceleration.  If  you do that the answer turns out the same way -- the twin who went on the trip ages less.I am quite comfortable with new ideas.  I am also quite comfortable evaluating incorrect interpretations of physical principles.  Yours falls into the latter category.  There is no experimental or theoretical evidence anywhere to support the notion of absolute motion.  You have not even proposed the reference frame that one would use as the basis for "absolute rest" merely asserting that it exists.  If it exists then what is it?  If you have a real theory, other than that simply general relativity is "wrong" then present it.  As far as physicists dying and acceptance of absolute motion goes, you are a bit over 100 years too late.  The physicists who believed in that concept are now long dead.  The smarter ones of that era saw the experimental data from several experiments, including Michelson-Morley and accepted Einstein's special theory of relativity.  It has served quite well since then, and with the advent of general relativity a few later the theory has only become stronger.  If you are looking to an arena in which general relativity may need to be revised, you might take a look at situations in which quantum effects are important, such as near black hole singularities or the big bang singularity.  We know that there are problems with general relativity, quantum mechanics or both that must be resolved to explain what is going on in those situations.  But with regard to more mundane situations, you are simply barking up the wrong tree.Bottom line:  You have made it quite clear that your notions have no basis in either the data from physical experiments nor can they be derived from accepted physical principles.  In fact they contradict both.  You don't know what you are talking about.  <div class="Discussion_UserSignature"> </div>

vandivx · Aug 14, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> There is no experimental or theoretical evidence anywhere to support the notion of absolute motion.  You have not even proposed the reference frame that one would use as the basis for "absolute rest" merely asserting that it exists.  If it exists then what is it?  If you have a real theory, other than that simply general relativity is "wrong" then present it.  Posted by DrRocket</DIV> simple deduction that anybody here could have done (and I am amazed forum fell silent on this thread given any cranky ideas typically receive numerous comments from various people here, I take that as positive sign in my favour) is as follows: absolute rest frame is that one in which the passage of time is maximized, clocks in any other linearly moving frames (moving in any direction) all run slower than the clock which finds itself at absolute rest in space and whose time passes faster when compared to all other clocks moving relative to it (of course the talk is only of uniform motion)  I happen to have a theory but it is still up here - knocks on his forhead after the fashion of Mozart when being querried where is the written composition for the new opera in Forman's famous moviebut point is why present more when all I get from you that I don't know anything and that my basic physics are all wrong (I suppose that refers to changes I propose and of course new physics are not likely to agree with old ones) and that I go against what was settled century ago and that experimentalists have determined once and for all that something is so and so, why bother fighting you at each and single point when clearly you are steadfastly sold on defending physics as it stands and arrogant to boot - if physics today is so right why is it stalled for like half a century now, you talk about working on details (on quantum level nonetheless) while arrogantly assuming the basic physics is right and settled once for all times and can't be wrong, how arrogant, a bit more modesty would behoove you I dare say

As far as physicists dying and acceptance of absolute motion goes, you are a bit over 100 years too late.  The physicists who believed in that concept are now long dead.  The smarter ones of that era saw the experimental data from several experiments, including Michelson-Morley and accepted Einstein's special theory of relativity.  It has served quite well since then, and with the advent of general relativity a few later the theory has only become stronger.  If you are looking to an arena in which general relativity may need to be revised, you might take a look at situations in which quantum effects are important, such as near black hole singularities or the big bang singularity.  We know that there are problems with general relativity, quantum mechanics or both that must be resolved to explain what is going on in those situations.  But with regard to more mundane situations, you are simply barking up the wrong tree.

all I can say, its like if I heard someone say to Copernicus that Ptolemaic theory of heavenly spheres have served us so well for so many centuries, that we only need to reconcile it here and there to iron some details but with regard to its basics we are simply barking up the wrong tree...now that is just an analogy and I am not saying today's physics is quite as wrong as Ptolemaic system was but it needs some changes as pig needs rubbing <div class="Discussion_UserSignature"> </div>

vandivx · Aug 14, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>So both speed and gravity can affect time.  And mass is obviously related to gravity so there is an effect of mass in that sense.  Posted by DrRocket</DIV>you should learn some basic physics I'd say mass, that is inertial property of matter 'affects time' on its own, quite appart from just being 'related to gravity' - mass (or matter of a given mass to be precise) when made to change velocity (accelerated) slows (affects) the passage of time 'You don't know what you are talking about.' I advise you to read any relativity textbook     <div class="Discussion_UserSignature"> </div>

derekmcd · Aug 14, 2008

I think the only way you are going to achieve an absolute rest frame would be to bring the universe to absolute zero where there is no motion.  AFAIK, this is theoretically impossible and would violate the third law of thermodynamics. <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

vastbluesky92 · Aug 14, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>'You don't know what you are talking about.' I advise you to read any relativity textbook     Posted by vandivx</DIV>Wow, I've seen that said a lot on these forums and even said it a couple times myself, but I never expected someone to say it to DrRocket. He's probably the person on these forums (at least who posts A LOT) who knows the most about physics and I bet he's read higher level relativity tetbooks than you ever will. Plus your post pretty much just refrased what he said. <div class="Discussion_UserSignature"> --____________________________________________-- Don't be too hard on me...I'm only in PHY 1010

The following goes without saying: </div>

vandivx · Aug 14, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Wow, I've seen that said a lot on these forums and even said it a couple times myself, but I never expected someone to say it to DrRocket. [...] your post pretty much just refrased what he said. Posted by vastbluesky92</DIV> well, he was in error there (one of serious omission in the context) and although I noticed it right away I didn't point it out at the time because it is not my habit to go after people's throat, not cutting them any slack and putting them down in arrogant and overbearing fashion whenever they open flank as he does it (about two years ago there was another one such denizen on forums here who got banned in the end for being overcritical of people in very much this way, the name was something stevewh or something), if you didn't notice he goes after me in particular, whenever I post and it is not to his taste, right or wrong, watching for any avenue I leave open to misinterpretation to make the worst of it and jump on me, even if I should be in real error that is still no manner the way he comes at me or others at the time I simply posted about mass and acceleration and time dilation in subsequent post the way it should be done and would have left it there if he didn't feel the need to slight me arrogantly and in exceedingly overbearing fashion at every opportunity as he does it since that thread on 'unrecognized geniuses' - there my views on the subject hit him very personally I believe and I made him my enemy because he is clearly one of those who know their physics, I hand it to him, but who are as sterile as doornail when it comes to doing anything with that knowledge except routine work, the likes of him lack genius talent and typically substitue for that the most thorough learning of the details of science in false belief that that is the way to its advancement but instead they end up as the Salieri's of science and they develop hate for anybody who shows any sign of true genius or stands up for such as I did on that thread, the same way Salieri was shown in the movie to end up hating Mozart, I like that movie a lot and watched it numerous times (maybe it is not faithfull to actual historical events but that is besides the point, the movie perfectly illustrates timeless animosity of mediocrity towards genius)  Replying to: <DIV CLASS='Discussion_PostQuote'>He's probably the person on these forums (at least who posts A LOT) who knows the most about physics and I bet he's read higher level relativity tetbooks than you ever will. Posted by vastbluesky92</DIV>yes, he does post A LOT, if you ask me he posts way to much, used to be months when all threads ended up capped by his having last word, when he showed up here first time moderator was taken aback by that even but could say nothing because it wasn't really spam, just somebody exhibiting his need to show he knows it all and doing it in overbearing fashion which earned him comment by somebody here telling him to 'come off his high horse' and it was a very fitting comment, albeit useless as it turned up  I would agree with you that he has likely read way many more books and deeper ones on the subject than I did but I ask again, is he somebody who made his name in science because of that? what good did it do him and why he now uses that knowledge to bash others overhead with it and do it in the fashion he does it? arrogant and overbearing? that is no overstatement even coming from me from what he posted when he showed up here not long ago, I take it he is somebody rather older, probably pensioned and with rich life in science/ingeneering behind him and his attitude is - before you want to make something new you got to know all the details including historical ones of the science/its field at handbut that is where he is sadly mistaken, to be able to do something new one only needs to have the knowledge of the essentials of the field of science at hand (which it typically much smaller part of the field than people might think) and then specialize in some narrow area of it but only as is necessary and determination of what is essential and what is not is precisely the genius stuff to determine while what is necessary follows from the work as it proceeds, if it becomes clear in the course of it that more detailed knowledge is needed, one goes and studies the fileld some more, but it would be a big mistake to burry oneself in undifferentiated details of everything, encyclopedic knowledge is anathema to anybody who has ambitions to advance scienceof course once that is said, it is very easy for anybody to jump in and make it look like one is claiming that ignorance is the way to advancement, but that is hate speaking out, make no mistake regarding special relativity one of the things I worked out was the reason why the speed of light is constant (unchanging in various moving reference frames) - question which greatly puzzled physicists when special relativity came out and I dare say it still puzzles at least some students (however in these modern times people tend not to wonder much about anything), Einstein made it a postulate on which his theory stood, which he used as its starting point, now I can tell you and it shouldn't come as any surprise that I didn't need any deep and arcane knowledge of special relativity - if such would be necessary for that, the legions of phds out there would have found it out long ago before I did, there are way smarter people in the field than myself, same was true of Einstein in his times for example, there is wealth of people out there much smarter when it comes to mathematics and to knowing most minute and arcane details of the subject, BUT the fact is nobody did find it out and I gave you a clue just above why not I was asked to come out with it if I have a theory, which I do have but I don't feel like that in the face of animosity I meet with due to that person here (one has enough of it having to deal with the usual scepticism and misunderstanding inevitable as it is though whenever one tries to come out with something new), never mind that the work is largely not written out in some presentable form, thing is whenever I post something I meet with attacks typically on irrelevant points like historical details, attacks which are motivated to shut one and bogged down before one can start talking much about anything or else there is silence, both are as off putting as can be above here I tested waters with the argument for absolute space and I know as anybody how dead in the water this subject is nowadays and don't need to be told, especially not in the manner it was done, however I believe the time dilation due to uniform velocity is one rare, perhaps single direct proof of it for all that want to see it (SR in effect disproves itself on relativity point over time dilation effect as being due to uniform motion but the point is so weighty that it blinds people into not seeing it or not wanting to admit it - the fact that physics (GR) can calculate the time dilation in twin experiment correctly has nothing to do with my argument, I never claimed it is paradox and that physics can't deal with it properly, just that if time dilation is really due to uniform motion, then uniform motion is no longer relative, nothing more and nothing less) and I believe it is one point which could be argued for on its own without having to present the whole theory (else I wouldn't bring it in to argue it) and while trying to bring it out before people I get told I don't know anything about basic physics and repeatedly get offered explanation of relativity and that twin paradox can be dealt with as if I ever disputed that... remainds me of that thread I once had over length dilation in SR, was it with Speedfreek or somebody else? at least I didn't get abuse in that thread but typically for such threads where I bring some true puzzle to fore, few people took part in it and those few that did besides the one I mentioned missed my point altogether and in the end nobody admitted even that I might be right after I managed to get the point across and they couldn't argue against it <div class="Discussion_UserSignature"> </div>

DrRocket · Aug 14, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I think the only way you are going to achieve an absolute rest frame would be to bring the universe to absolute zero where there is no motion.  AFAIK, this is theoretically impossible and would violate the third law of thermodynamics. Posted by derekmcd</DIV>It would also violate the first and second laws.   The first because at absolute zero you are in the state of lowest energy and since it is the entire universe that we are talking about all of that earlier energy ought to be around somewhere.  The second because absolute zero is a state of minimal entropy and the overall entropy of the universe can at best only remain constant, but in fact is continually increasing.I hadn't thought of it, but the notion of reducing the universe to absolute zero is somewhat unique in that it would simultaneously violate all the laws of thermodynamics.  That is pretty impressive. <div class="Discussion_UserSignature"> </div>

DrRocket · Aug 14, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>you should learn some basic physics I'd say mass, that is inertial property of matter 'affects time' on its own, quite appart from just being 'related to gravity' - mass (or matter of a given mass to be precise) when made to change velocity (accelerated) slows (affects) the passage of time 'You don't know what you are talking about.' I advise you to read any relativity textbook     Posted by vandivx</DIV>I have read several relativity books.  I have even understood them.It is pretty clear that at least one of us doesn't know what he is talking about, in a big way.  <div class="Discussion_UserSignature"> </div>

vandivx · Aug 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'><div class="Discussion_PostQuote">I think the only way you are going to achieve an absolute rest frame would be to bring the universe to absolute zero where there is no motion.  AFAIK, this is theoretically impossible and would violate the third law of thermodynamics. Posted by derekmcd </DIV> </div> Replying to: <DIV CLASS='Discussion_PostQuote'>It would also violate the first and second laws.   The first because at absolute zero you are in the state of lowest energy and since it is the entire universe that we are talking about all of that earlier energy ought to be around somewhere.  The second because absolute zero is a state of minimal entropy and the overall entropy of the universe can at best only remain constant, but in fact is continually increasing.I hadn't thought of it, but the notion of reducing the universe to absolute zero is somewhat unique in that it would simultaneously violate all the laws of thermodynamics.  That is pretty impressive. Posted by DrRocket</DIV> yes, coming to rest in that sense (being at zero kinetic energy on particle level) would violate well established physics  when I said 'at rest in space' I didn't mean that somehow all the oscillations of all particles of matter around their center of mass would stop, that wouldn't happen when a chunk of matter came to rest in absolute space and if we talked about individual particle(s) then they couldn't be brought to rest in space in that sense - that they would stop jiggling around their CM, what I meant was their translational motion would be zero relative to space  this oscillatory jiggling and wiggling that particles of matter perform unceasingly at least to some minimal extent as physics today knows is completely different matter from what I talk about and would go on as it ever did even while the gross matter composed of them were to come to be at rest in absolute space, in same way that the stone dorstep at my place here is at rest relative to Earth all the while its particles are oscillating and doing what not within that stone slab, being at rest generally doesn't rule out such oscillatory motions, else we couldn't talk of a rest in regard to anything could we  again, I meant translational motion which is enduring which would cease relative to space, be it particle that performs it or a whole macroscopic chunks of matter, not microscopic particle oscillations around CM, if matter did come to 'rest' in space in that way, it would of course violate some very basic and very securely established laws of physics as you say (I wish you left out the irony contained in the term 'impressive') and while in some fantasy one could imagine that kind of rest in space, it doesn't happen but just because there is this barrier to absolute rest in space on fundamental particle level, still the idea of rest in space being valid for translational (non-oscilatory in microscopic sense) motion is no less than revolutionary idea, old as it may be, in the end it is not important that matter can't be brought to rest in space in the sense of each particle of it coming to rest but that we have a way to establish reference point for exploration of cosmos such as in the study of CMB and such likes (mainly it would be usefull in macroscopic physics (cosmology), not microscopic ones (particles  or physics on relatively small scale) the whole point of being able to physically establish state of absolute rest in space is not that one could put matter into that state (in all respects including its individual particles) but that it can serve as a reference point, same as we have the concept of lowest temperature reference point of absolute zero while nobody complains that we can't ever reach it, same with the speed of light which gross matter or its particles individually can't reach  the idea of absolute rest in space of course doesn't throw out the concept of relativity out the window altogether, it still doesn't enable us to mark a definite place in space and in that respect relativity would live on albeit more limited as relativity of place in space but not relativity of motion, furthermore as daily life goes motion would be regarded relative I suppose even after the absolute space were accepted in physics because it is 'common sense' thing with modern man and because the concept has no utility in normal life of peoples, even in physics, the field of classical mechanics for example shouldn't change I think although what would change is hard to determine now, myself I only gave that a passing thought so far because that's not important from my point of view, all I care about is to find out how nature ticks

vandivx · Aug 15, 2008

when I criticize SR or GR and claim they need to be reworked, I don't mean everything about them is wrong, in particular all the computational results they yield would stay intact, those are simply too well established as for example Newton's laws of gravitation and computations based on them still hold today in first approximation, when flying to planets nowadays, GR only provides some very minute corrections while most of the journey could still be projected if need be, using just that centuries old gravitational law and classical mechanics (which I believe is actually the case) maybe the biggest change would come regarding the (in)famous space contraction in SR which never had any direct experimental basis and was just the result of the theoretical need to enable us to deal with the fact that the speed of light was found to be constant in all reference frames which it still would be in the reworked theory I hasten to say <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-smile.gif" border="0" alt="Smile" title="Smile" /> except that we would understand the physical reason why it stays constant and space contraction would be conceived in different way (it has to do with the reason behind constancy of light speed) - similarly as initially it refered solely to physical length contraction and only later the shift came about and contraction was attributed to space itself, and I propose now another change, isn't it being said that the third time is the last time? all this talk of space contraction really begs the absolute space but that issue was skirted by taking that to mean shrinking of the distance between bodies of matter, it has its own pitfall though - the typical talk about space ships traveling at relativistic speeds which everybody met with at one point or another and which is done as physical illustration of special relativistic calculations implies a paradox* (as I pointed out in that old thread I mentioned in my other post) and so in our modern times such talk is not part of offical textbooks from what I have noticed, it mostly survives on net on forums it seems and in some physics for layman books of course that paradox dawned on me only when I was backwards checking these practical examples of illustrated SR effects while looking at them with my newly gained knowledge regarding space contraction, without that I admit I didn't see that in the past when I came across them - likely as others before me I just let it go thinking that I am doing something wrong and if I return to it later or read up on it someplace that it will turn up I was mistaken, after all the calculations of SR do come out right, so what..., that is very much similar to confrontation with 'unprepared' mind  the idea that time dilation implies absolute space, while I fully expect steep going trying to persuade others to see it as I do, slighting remarks should not be part of it as they shouldn't be part of any discussion * the paradox was in 'failed symmetry' in illustration of SR effect - briefly put it was about explanations of why an astronaut traveling in his ship at speed nearing the speed of light c measures an oncoming ray of light traveling at speed c - it is explained by outside observer (who would othewise expect the measurement to come out faster than c) that the astronauts ruler shrank and so the light had shorter distance to travers as well as time in the spaceship dilated which both conspire that we can see why the astronaut measured the speed c and not any faster one... but now how about making it not an oncoming but catching up ray of light from behind in the same setup, in that case it would seem the ground observer would require that the astronauts ruler would dilate (grow longer) and time should contract (pass faster) in order for the measurement to come out right according SR, to compensate things so that the measured speed would come out c and not less than cI claim there is contradiction there because shrank ruler and dilated time cannot be used to explain why the speed of ray of light catching up  the spaceship from behind would be c, in order for both measurements to come out right, one would need at the same time and in the same respect both ruler expansion and contraction as well as time dilation and contraction and that's paradox now I don't care what SR calculations say, I am talking about physical interpretation behind those calculations, come to it maybe they don't really come out as expected after all, I admit I am not strong on mathematics in general, but it wouldn't surprise me that people don't bother to cover all possibilities in an experimentnotice that in this thought experiment it doesn't matter whether one considers the physical ruler to shrink or whether it is 'space' that shrinks, such as the celing and floor of the spaceship coming closer together because that comes to the same thing, one could measure the speed of light based on measuring its trip from the time it enters the ship and before it hits or exits via the opposite 'wall', be it the floor or ceiling, or windows in them respectivelythe point is that if I am right, then SR theory should forget about any illustrations of its principles on physical basis via such illustrative examples  <div class="Discussion_UserSignature"> </div>

DrRocket · Aug 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>... maybe the biggest change would come regarding the (in)famous space contraction in SR which never had any direct experimental basis and was just the result of the theoretical need to enable us to deal with the fact that the speed of light was found to be constant in all reference frames which it still would be in the reworked theory I hasten to say except that we would understand the physical reason why it stays constant and space contraction would be conceived in different way (it has to do with the reason behind constancy of light speed)...Posted by vandivx</DIV>There is experimental evidence for length contraction.  Length contraction and time dilation are two sides of the same coin.  The decay of the mu meson (in modern terminology called the muon) is a case in point.  These particles are formed high in the atmosphere by cosmic ray collisions and are found to penetrate our atmosphere farther than would be expected from the known decay time of these particles.  The explanation for this phenomena lies in the Lorentz transformatin of special relativity.  From the viewpoint of an earthbound observer, time dilation allows the muon to penetrate deeper into the atmosphere because it has more time to do so.  From the point of view of the muon length contraction in the permits the penetration during a normal lifetime.If you accept only two premises: 1) that the laws of physics are the same in all inertial reference frames and 2) that the speed of light is the same in all inertial reference frames, then on the basis of mathematical logic alone you must accept the Lorentz transformation that is derivable from those two assumptions.  With the Lorentz transformation you get all of the features of special relativity including length contraction, time dilation, relativity of simultaneity, etc.  You cannot accept only part of the package, it either the whole thing or nothing.  <div class="Discussion_UserSignature"> </div>

derekmcd · Aug 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>* the paradox was in 'failed symmetry' in illustration of SR effect - briefly put it was about explanations of why an astronaut traveling in his ship at speed nearing the speed of light c measures an oncoming ray of light traveling at speed c - it is explained by outside observer (who would othewise expect the measurement to come out faster than c) that the astronauts ruler shrank and so the light had shorter distance to travers as well as time in the spaceship dilated which both conspire that we can see why the astronaut measured the speed c and not any faster one... but now how about making it not an oncoming but catching up ray of light from behind in the same setup, in that case it would seem the ground observer would require that the astronauts ruler would dilate (grow longer) and time should contract (pass faster) in order for the measurement to come out right according SR, to compensate things so that the measured speed would come out c and not less than cI claim there is contradiction there because shrank ruler and dilated time cannot be used to explain why the speed of ray of light catching up  the spaceship from behind would be c, in order for both measurements to come out right, one would need at the same time and in the same respect both ruler expansion and contraction as well as time dilation and contraction and that's paradox Posted by vandivx</DIV>You are going to have to explain your paradox a bit more clear.  First issue I see is that and outside observer (a third reference frame) most definitely can measure closing speeds greater than C of two objects outside their reference frame.  Second issue is that you can not have length 'expansion' unless you have a negative velocity... impossible.  Or travelling greater than C... impossible.I think the issue with your paradox (if I'm understanding it properly) is the relativity of simultaneity.  The light beam from behind, according to the observer from the source of the light, will see the light slowly catch up to, and pass the astronaut.  The observer from the source, outside the astronauts reference frame, does not recognize the length contraction of the astronaut.  Everything appears normal to the outside observer. The astronaut will see the light travelling at C in his own reference frame and so will the outside observer, but they will disagree what time the light was emitted and how far it travelled. <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

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