# Yet another (specific) speed of light question...

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#### heyo

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Greetings, fellow atoms, molecules, planets, etc...<br /><br />(these forums rock, BTW. I have learned so much)<br /><br />I posted this question in another one of the <br />ongoing "speed of light" threads that I jumped in on, but I think I got in late on that so it never really went anywhere, so if I may be so bold, I am starting a new thread.<br /><br />This is what I am confused about:<br /><br />According to relativity, the idea of "motion" or "velocity" only has a meaning when used to describe motion or velocity relative to some other object. There is no state of absolute rest or absolute velocity. You can describe the same objects velocity many different ways by stating it relative to various objects. ("Away from that asteroid at 1000mph", "towards this asteroid at 500mph", "away from this space station at 3mph" can all be correct in describing the same object's velocity at the same moment.<br /><br />As far as I know, there is no background "ether".. no absolute point in background space where, if your velocity is zero relative to it, you can absolutely and truthfully say you are "motionless", nor can you ever say, *absolutely* that "I am going in THIS direction at 100mph. Period."<br /><br />So if an absolute velocity can *never* be defined, how can a limit on absolute velocity ever be defined?<br /><br />To simplify it in one sentence as I did in the other thread (please forgive me for repeating myself)..<br /><br />Nothing can move faster than light <b>*with respect to what*?</b> The background space? If that were true, there COULD be states of absolute velocity and absolute rest.<br /><br />Thoughts?<br /><br />Heyo<br /><br />

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#### vogon13

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You carry reference with you, wherever you go, whatever your speed. Just measure the speed of light and there you are and there you go, he said slyly. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

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#### newtonian

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Heyo - I agree, but it is so complex I did not respond to your post. Sorry about that.<br /><br />For example, consider if FTL (= faster than light) inflation theories are correct about FTL expansion of our universe early in its history.<br /><br />That would mean our origin reference point at that time after the big bang has expanded FTL from some very different reference points in our universe which now lie beyond our visibility horizon.<br /><br />Then, there is the question of reference points in other universes, and how you would measure distance - i.e. in what dimension - which involves String theories and Membrane collision theories for the origin of our universe.<br /><br />There are also theoretical astronomers that propose some of our distant universe is already once again expanding FTL from us at this time, though we see toward those points as they were 13+ billions of years ago.<br /><br />To really understand this, we would need to know how inflation was caused and how acceleration of expansion is being caused - and I am not certain which educated guess is close to the truth, if any are.<br /><br />Of course, one has to decide which reference point to measure speed from. <br /><br />The singularity at the origin of our universe?<br /><br />Earth now?<br /><br />The center of gravity of the Milky Way galaxy?<br /><br />The center of gravity of the Great Attractor?<br /><br />The center of gravity of our universe at this time, or at some past time- whereever that is!<br /><br />God's location?<br /><br />I think you realize the problem with reference points.<br /><br />We often say we are heading towards Andromeda. However, one could also say Andromeda is heading towards us!<br /><br />I haven't answered your question - I'm just adding other factors which I think are relevant to finding the answer..

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#### heyo

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Newtonian, Interesting stuff, indeed.<br /><br /><i>Of course, one has to decide which reference point to measure speed from. </i><br /><br />Good question, and possibly the crux of my point.<br /><br />I am trying to simplify the question a bit, for my own sake even...<br /><br />We know that light moves 186,000 miles/sec. If I am in space and I turn on my flashlight, the beam of light will race out from the light at that speed. But if I and my flashlight light are moving forward) at .9999C will the beam just creep out ahead of it slowly?<br /><br />Let me try and set up a scenario:<br /><br />Lets say you have a really long bar or some kind of frame. On one end, you attach a laser which points down the length of the bar parellel to it.<br /><br />Along the length of the bar you place light detectors that can detect when the light hits the detector.<br /><br />So just for now, lets leave out all frames of reference except for the scientist who goes along with the detector, perhaps in a chair attached to it.<br /><br />So the whole setup is siting still, you turn on the laser. You do some calculations based on the times that the detectors went off and you calculate that the end of the beam passed through the array of detectors at speed C.<br /><br />So now lets say the whole setup is cruising through space at .75 C, in the laser-beam-pointed-forward direction. You hit your beam switch, and you do your calculations based on the times that the detectors went off, would your calculations still tell you that the end of the beam passed through the detectors at speed C?<br /><br />I believe Einstein presumed that this would indeed be the case, but would this not mean that the end of the beam was moving at /> C? Would it be the time dilation from the reference frame of the detector setup that caused the calculations to come out to C, despite the fact that the beam propagated slower from a stationary observer's frame of reference? (Or from an "absolute" frame of reference if there is such a th

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#### spaceman186000mps

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Or to what level of the many layered multi-verses that do exist?<br /><br />Unless we can distinguish what and where the center of the great attractor is, <br />I think one could safely assume that absolutely nothing of matter, gas or vacuum is standing still.<br /><br />Then I wonder if, the vacuum void of space itself is moving in relationship to other vacuum space around or near a light wave or particle? <br />What is currently known about the studies of the properties of space vacuum itself?<br /> <div class="Discussion_UserSignature"> <p><strong><font size="2" color="#3366ff">70 percent of novel proceeds </font></strong><strong><font size="2" color="#3366ff">www.trafford.com/06-1593</font></strong><strong><font size="2" color="#3366ff"> are donated to </font></strong><strong><font size="2" color="#3366ff">www.caringbridge.org</font></strong></p> </div>

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#### unclefred

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Heyo, your entire discussion is based on light acting as a particle and you end up with just more questions. Try again with the assumption that light acts as a wave and you will get the right answer.<br /><br />If light is a wave, it will travel at a set speed for the medium that it is traveling in, no slower and no faster. The medium determines the speed. In some cases the medium just happens to be a vacuum. The sound from a train horn travels the same speed ahead of and behind a train no matter how fast the train is moving, or even if it is stopped. So why would one expect light from the headlight to be different? One shouldn't expect it and in real life it is not any different. Does that mean that the speed of the source has no effect? No, speed does affect the light. For both light and sound it is Doppler shifted.<br /><br />

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#### heyo

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Right, but even if you think of light as a wave...<br /><br />and of course my whole discussion is assuming that the medium is the vacuum of space.<br /><br />My point is how do you KNOW your absolute position or motion relative to the vacuum?<br /><br />Maybe it's possible that you can, but if that IS the case, than velocity and motion WOULD have a meaning without being relative to some other object.<br /><br />Everything that's been said in the thread is correct, but it still hasn't answered the question. Maybe I am just looking at it wrong.<br /><br />Light, as a wave or particle, travelling through the vacuum, can only travel at a maximum of 186,000 miles per hour *towards or away from what*... <b>*relative*</b> to what?<br /><br />If the answer to that question is: relative to the *background space* or the *vacuum*, then that would mean that the notion of there being <b>no such thing as absolute motion, nor an absolute motionless state, nor an absolute velocity without somethjing to compare them to,</b> can't be true.<br /><br />Am I way off here?<br /><br />Heyo<br /><br />PS. Thanks for the replies, everyone. ;-)<br /><br />

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##### Guest
I've brought this up in various guises even in my topics but have not had an answer, I don't think anyone knows.<br />I'm trying to formulate another way of looking at light but it's so outrageous I can't post it.

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##### Guest
okay.. heres the deal. Light is a Constant. just like pi and avagadros number. the fastest velocity possible by anything. the only ABSOLUTE in any system is light. no stationary point needed. no reference point needed, because you have the only one you need, the only absolute: C <br /><br />now.. flashlight on a ship: youre traveling at .75C now, you need to remember, relativity. as you move closer and closer to the speed of light time slows down. the astronaught, the ship, and everything in that object traveling at .75C EVERYTHING is moving at a reduced time frame. So, because of that, to the person on the ship, the flashlight will work just fine. because HIS timeframe is reduced. And while mathematically, the light(its a constant, remember) will travel at .25C to the target, to the observer on the ship, it will look as if it was instantaneous... now you probably see where this is going... as you travel closer and closer to C... .99C the light will propigate at C cause its a constant.. will mathematically travel at .01C to the target, but because of the reduced timeframe, everything is moving at 1% of normal time. AT C to a casual observer.. the light will not propigate from that flashlight mathematically because time on that ship will have completely stopped..BECAUSE you can no longer use the ONLY TRUE REFERENCE POINT YOU HAVE...LIGHT. and the astronaught, will never know because thats where God divided by 0 and math, time, space, and everything else just stop working

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##### Guest
Now that i read it, it sounds like babbling... i should try to make it clearer.

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#### newtonian

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Heyo- Sorry for the delay. I was gardening and meditating - the good news is I think I finally understand part of this so I can explain it!<br /><br />You all - feel free to critique this.<br /><br />This concerns only our universe - not others.<br /><br />OK, as far as we know, at least at this time, the speed of light is the speed limit of matter and also light. Since your first post referred to motion of objects, I am responding concerning matter.<br />The short answer is that there is another type of motion besides what we usually measure.<br /><br />That would be the expansion of the fabric of space.<br /><br />There are a number of models, but the point in common is that reference points in the fabric of space are expanding from each other and further points are expanding faster, and this type of motion has no speed limit - which is why inflation theory is possible and why some of our universe may already be expanding again FTL.<br /><br />To better understand this, you need to have a mental picture of the entire universe, seen and unseen ( unseen = beyond our visibility horizon).<br /><br />And here is my favorite model describing the expansion of the fabric of the universe:<br /><br />(Isaiah 40:22) There is One who is dwelling above the circle of the earth, the dwellers in which are as grasshoppers, the One who is stretching out the heavens just as a fine gauze, who spreads them out like a tent in which to dwell, <br /><br />[NOTE: This would be a flat model, not the balloon model]<br /><br />OK, picture our universe as like a fine gauze (the meaning of the Hebrew word) type of fabric. Now compare this to what is actually observed by astronomers, namely: expanding threads and filaments [astronomers independently chose these terms] roughly similar in appearance to a fine gauze magnified many times.<br /><br />As I said, overall each reference point on that fabric is expanding from every other reference point, and more distant reference points are expanding faster.<br /><br />HO

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##### Guest
okay... lets see if i can rephrase it a bit. <br /><br />First: some things to remember.<br /><br />1) light is a constant in a vacume. <br />2) light can stretch and contract<br />3) light can either be a wave, or a particle, depending on how you look at it. <br />4) light doesnt need to travel at the speed of light relative to anything because (see 1) and because (see 2)<br />5) time is a fundamental property of light and vice-versa, and in essense there is time only because we need a way to measure light. <br />6)time slows down to the person or object that is appoaching the speed of light, yet the speed of light remains constant. <br />7) the only velocity you should be worried about is %C because that is the only true reference. In other words: How fast am i traveling in relation to my light propigation. Direction or starting point is meaningless as light proigates as a wave. if you want to know what you would look like to someone on a planet as you wizz by them at .75C imagine a boat going over water creating waves, where you are along those waves, and how youre traveling across those waves, is how one would percieve the ship as it passed by a planet. travelign at .75C towards an observer, the light would be very compressed into the lower wavelenthgs (blueshifted) and as it traveled away from you it would be very redshifted. but still, its light would strike you as any other because (see 1) its still coming at you at C weather its towards you, away from you or at a tangent to you. The wave propigates at C reguardless of direction. <br />8) time moves slower on the ship in direct proportion to the increase %C BECAUSE (see 5) <br />9) like light, time is only relevant to the observer. and remember, time is not constant. <br /><br />okay.. now... flashlight turned on in a ship traveling .75C. Mathematically, because C doesnt change, then the light would strike the target at .25C (doesnt that sound much SLOWER) than normal? but to the astronaught who is ALSO traveling at .75C

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##### Guest
If a LASER light was used & I accelerated to-wards it I've read here that it would be increasingly blue shifted as I would be travelling through it. The problem there is it would no longer be a sine wave & as such would produce sidebands as shown by Fourier analysis but I've never seen this stated. Doesn't this mean the mechanism for Doppler shift is erroneous.<br />Further as C is a constant is Doppler shift the only means of knowing speed w.r.t. C in order to know we've not exceeded C

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##### Guest
<blockquote><font class="small">In reply to:</font><hr /><p>okay.. now... flashlight turned on in a ship traveling .75C. Mathematically, because C doesnt change, then the light would strike the target at .25C (doesnt that sound much SLOWER) than normal? but to the astronaught who is ALSO traveling at .75C, but is moving at the slower time frame, things would just look normal to him on the ship. untill he reached C. But im sure that its mathematically impossible for a reason.<p><hr /></p></p></blockquote><br />I may be misunderstanding that but it seems at variance from astronomers using C as a means of distance measurement <i>irrespective</i> of Doppler shift.

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#### spaceman186000mps

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Greetings, fellow atoms, molecules, planets, etc... <br /><br />I'm the et c a comet<br /><br />Anyway,<br />I was wondering, what some of you good heads thoughts are on this experiment about the speed of dark?<br />http://www.ysa.org.au/themill/1998.3.darkspeed.html<br /> <div class="Discussion_UserSignature"> <p><strong><font size="2" color="#3366ff">70 percent of novel proceeds </font></strong><strong><font size="2" color="#3366ff">www.trafford.com/06-1593</font></strong><strong><font size="2" color="#3366ff"> are donated to </font></strong><strong><font size="2" color="#3366ff">www.caringbridge.org</font></strong></p> </div>

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#### heyo

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VLAD, Newtonian, siarad, thank you all for the replies...<br /><br />I have learned a great deal by reading your posts.<br /><br />My eyes are more opened to the subject, for sure, however my conflict still exists. Or maybe it's not a conflict anymore, but I will explain a bit of what I gathered by reading up on this thread this morning.<br /><br />Allow me to qoute VLADIUS first, if I may:<br /><br />- snip -<br /><br /><i>okay.. heres the deal. Light is a Constant. just like pi and avagadros number. the fastest velocity possible by anything. the only ABSOLUTE in any system is light. no stationary point needed. no reference point needed, because you have the only one you need, the only absolute: C</i><br /><br />- end snip -<br /><br />This seems plausible and correct to me. However, if you read what Vladius has written there, it seems to me that it flies in the face of Einstein's principle that there can be no state of absolute rest or absolute velocity for a physical object. Whether we are talking about the motion of light or matter, it is still an entity or physical property propagating through space at an *absolute velocity* relative to nothing but the vacuum. <b>If we can measure absolute velocity for light, we can measure it for a physical obect or particle as well, since both light and physical objects propagte through the same spacetime.</b><br /><br />Either I am very mixed up, or this tells me thee can be a state of absolute rest.<br /><br />A few posts later, in his post, Newtonian said this:<br /><br />- snip -<br /><br /><i>HOWEVER, THIS MOTION IS INDEPENDENT OF THE TYPE OF MOTION WE USUALLY MEASURE! <br /><br />The type of motion we usually measure would be like motion on the fabric, not the stretching of the fabric as in the Biblical illustration. <br /><br />[This explains why our local section of universe is converging on a Great Attractor rather than receeding from the thousands of local galaxies involved - it is local motion vs. overall expansion] <br /><br />Motion on the</i>

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#### igorsboss

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<font color="yellow">Nothing can move faster than light *with respect to what*? </font><br /><br />More precicely, information can not move faster than the speed of light, with respect to any observer.<br /><br />Some things do take place faster than the speed of light (ie. "spooky action at a distance"). However, none of these FTL actions can relay any information whatsoever faster than light. It happens, but there is no advantage to be gained from it.<br /><br /><font color="yellow">So now lets say the whole setup is cruising through space at .75 C, in the laser-beam-pointed-forward direction. You hit your beam switch, and you do your calculations based on the times that the detectors went off, would your calculations still tell you that the end of the beam passed through the detectors at speed C?</font><br /><br />YES!! Your calculations would still tell you that the end of the beam passed through the detectors at speed C!!! You have every right to be amazed, because it is indeed amazing, but true.<br /><br />How can this be?<br /><br />Well, you and your detector setup move through space at 0.75c relative to some observer. We'll call him Fred. He has a detector frame exactly like yours.<br /><br />As your detector setup moves through space at .75c relative to Fred, the length of your detector setup contracts (relative to Fred's identical detector) and time passes more slowly (also relative to Fred's identical detector)!<br /><br />How much contraction and how much time dilation is given by the formulas in special relativity. For further research, look for a factor called "gamma"...<br /><br />By the way, you would also observe that Fred's detector setup is contracted, and that Fred's time is also passing slowly.<br /><br />The missing piece of the puzzle is the idea that space and time are affected by relative motion.<br /><br />Strange but true. Does that help at all?

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#### nexium

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I agree some is counter intuitive. c+c+c+c = c.<br /> I'm reminded of an eposode of original star trek when Captain Kirk orders all ahead stop. The only nearby object was a nebula. I suppose Scotty and The Computer made a guess at the average vector velocity of the particles in the nebula to determine the amount of thrust required to approximate stop. Neil

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#### newtonian

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Heyo- Your welcome.<br /><br />And thank you Vlad and siarad also - but you all are referring to motion and light on/in the fabric of space. <br /><br />Heyo - Please see my response to you and others on the other current thread on this.<br /><br />The quick answer to your question is that there can be no speed or velocity when only one reference point is considered. <br /><br />The definition of reference point is a point considered stationary in reference to other points.<br /><br />However, if no other reference points are considered, then there is no motion (unless there is internal motion within the point of reference, as within earth as a reference point, of course.).<br /><br />Yes, everything is relative. Einstein was relatively correct.<br /><br />However, is space-time expanding faster than light, or is it limited to c while the fabric of space expands faster than c????<br /><br />Or is that a semantic misunderstanding?<br /><br />From what I understand, the fabric of space exists independent of time, i.e. it is 3 dimensional, not 4 dimensional. Space-time is 4 dimensional.<br /><br />Of course, the expansion of the fabric of 3-dimensional space is during the dimension of time.<br /><br />I know, btw, that the fabric of space may have 11 dimensions, as in one model of String theory.<br /><br />However, that is theory, not observation.<br /><br />In conclusion: Rest, relax. If you consider yourself at absolute rest......

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#### xmo1

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Warning: High likelyhood of unsubstantiated information. BS factor = [X4]<br /><br />The speed of light is measured from its point of origin to some other point. The speed of light can only be approximated. C is a variable with an assigned value used as a constant. My belief is that there is a state between matter and energy that exists just prior to entropy where matter (mass) may be excited to a state which allows modulated deresolution, quantum intradimensional travel, and reconstitution. I wonder if Exxon will pay me not to invent the device that could make it happen.<br /><br />The Earth travels about 33 million miles a day. Who needs a space ship? <div class="Discussion_UserSignature"> <p>DenniSys.com</p> </div>

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#### newtonian

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xmo1 - Just prior to entropy?<br /><br />Can you explain your hypothesis in more detail?<br /><br />The speed of light varies depending on the medium through which it passes. In a total vacuum it seems constant, at least at present locally.<br /><br />Are you aware of evidence that it is variable in a vacuum?

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#### xmo1

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Remember the warning:<br /><br />I understood E=MC^2 to mean energy results from mass at the speed of light, or mass turns into energy at the speed of light due to entropy. Could be that all energy in the universe is due to this phenomenon. Some Mathematicians may quote a more 'mathematical' interpretation, but I like my version which explains, to me at least, a number of things which are no longer considered common knowledge.<br /><br />I believe the answers we seek to the origin and growth of the universe, space and time travel, and interdimensional existence will be found in the morph of Plasma Physics with Particle Physics, and not so much from the initial experiments, but rather from the advanced applications that are sure to follow. There are things there that remind me of John Lear's discovery of America using a really fast aircraft (snicker).<br /><br /> />>Are you aware of evidence that it (light) is variable in a vacuum?<br /><br />No, but it doesn't surprise me. We have a periodic table of elements for mass. I would expect to see something similar for plasmas, along with a set of physical laws governing their states and interactions.<br /><br />I'm inclined to think there are some very important things, for lack of a better word, that remain to be discovered, which will revolutionize our current view of the possibilities inherent in our physical laws.<br /><br />Here are some Cherenkov radiation URL's if you are interested:<br /><br />Is Faster Than Light Travel Possible?<br /><br />Cherenkov Radiation<br /><br />Cherenkov Light<br /><br />"When a particle travels faster than the speed of light in water, it produces a shock wave that is the equivalent of a sonic boom made by a jet traveling faster tha <div class="Discussion_UserSignature"> <p>DenniSys.com</p> </div>

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#### newtonian

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xmo1- superbusy today, so I will respond better another day when the rains come.<br /><br />However, you misunderstood my post.<br /><br />Light speed is not variable in a vacuum (a pure vacuum).<br /><br />Light speed is variable depending on the medium it passes through.<br /><br />That is interesting about mass turning into energy at the speed of light. <br /><br />In our universe's origin, it seems that energy turned into matter which, if inflation theory is correct, was then expanded faster than light!<br /><br />That would be quite opposite!<br /><br />Temperature, I believe, is part of the answer.

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#### alkalin

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What care should be taken in discussing theoretical situations where values such as c may have little real application? For one thing, if there is an ether, or basic fabric to the universe, it does not affect light the way we would like it to. If it did, we would have long ago determined some kind of basic reference in space.<br /><br />Some of these problems stem from a lack of our concept of interpretation given by Einstein of the failure of the MM experiment. Light is both a particle and a wave, and has value c relative to its local reference frame. When you have captured a photon in your lab set up, the photon behaves as though this is it’s reference frame. That’s because this is it’s reference frame!! Quantum physics demonstrates the photon’s sensitivity due its wave properties in various slit experiments <br /><br />You cannot have a measure of c outside of the capture of the photon in your experiment. The way I see it is that when a photon’s waves are in close proximity to matter, the photon is speed regulated somehow by that local contact. Exactly how this works or theories behind it I’m not sure of, nor do I think anyone knows for sure.<br /><br />But such an idea implies that the photon’s velocity is not constant in a non-referenced vacuum. Current experiments even show, however, that a photon can be slowed or even stopped. So how can anyone still insist that light always moves at c? I suggest we are only just beginning to scratch the surface in understanding what is really going here.<br /><br />Also that Doppler directly results from slowing or speeding up of photons when they enter your reference frame. The photon’s waves are either shortened or lengthened relative to your immediate reference. My opinion on this one is that the waves stay perfect sine waves so allow no pointer to some sort of universal basic reference.<br /><br />None of this helps with the idea of what is an absolute reference in space somewhere, since all things are in motion with

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#### xmo1

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I think C is a constant. Light is radiation from a photon. Or is light a visible wave propagated from the movement of a photon? Through what? Yes my friends, it is a quantum space. Comments are appreciated.<br /><br /><br />God is an engineer who wanted us to figure out how he did it. I think it was an accident in his lab.<br /><br />To the particle physics students: Do not attempt to create a black hole on earth. We really don't know what might happen, and I don't want to be looking like a cartoon character just yet.<br /> <div class="Discussion_UserSignature"> <p>DenniSys.com</p> </div>

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