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Messages - David Cooper
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126
« on: 29/11/2012 21:53:52 »
I am not the one confusing theories here. Actually, you are. You keep attacking things I've said about one theory as if I'm talking about a different one. You don't seem to be able to compartmentalise them properly, and that's why your confusion never ends. This is impossible mis-communication (or intentional distortion by D.C.) I haven't distorted a thing - you imagine distortions wherever your ability to understand things hits a rock. " MM requires actual length contraction in an OGVT/LET type of theory." D.C. clarified that he invented "OGVT" as "old guy vacuum theory." That space is empty volume is the "vacuum" part. Stuff exists and moves in space. That takes "time." Time is not a fourth dimension. It just passes... Earth goes around the Sun... cesium atoms have a very precise and regular oscillation in atomic clocks. Indeed I did, and that's exactly what I though your theory was at the time, but then you keep wobbling into SR territory without seeming to be aware of what you're doing, so all I've been trying to do is pin you down as to what your position actually is. You now appear to be accepting that OGVT is indeed your position, in which case your claims of realism don't fit it because it conflicts with MM. I have never accepted 4D spacetime. Quite the opposite, as is evident above and in all my posts. How can I communicate with someone who presents my argument as the opposite of what I am saying? (Rhetorical. I can't.) If you don't do 4D Spacetime, then that pulls out a few rugs from under your feet - you have to have actual length contraction to account for MM. "Btw and finally, I find your mock post of my position, signed "O.G." very offensive, as follows:" So you said in your previous post, and as I said in my previous post it was in no way intended to mock anyone. I'm simply trying to get you to pin your position down properly. Recently you've been talking as if you've adoped 4D Spacetime into your model - you made it clear that you have no interest in any theories other than SR, so that automatically excludes what I correctly understood to be OGVT. It sounded as if you'd shifted ground and didn't want to say so. Now you've made it clear that this is not the case, so your position puts you in a place where you cannot account for MM. My intention was not to mock you in any way - I'm trying to help you state your position clearly so that it's possible for people to work out what you're on about. How condescending and arrogant! I have stated my position clearly and thoughtfully, expressed as "my position" in my own words.
You may think that, but you have the advantage of knowing what you think. What I see is someone squirming around and avoiding to answer questions which will expose his position as wrong, such as the crucial ones relating to the train thought experiment. I am "on about" the difference between apparent and actual contraction of physical objects. Not only do I not need your "help" for that, your "help" is just your own agenda ignoring, getting it wrong, and totally distorting what I am actually saying. You don't have apparent contraction in your model unless it has Spacetime in it, which you've now stated categorically that it still doesn't. That being the case, I can now state categorically that your model conflicts with MM because it fails to allow for actual length contraction. The train thought experiment would show you that if you bothered to work your way through it. I showed how off your mock quote was, but you didn't even acknowledge how i corrected your misrepresentation of my position. You're misrepresenting it as being mocking when it was nothing of the kind. That's very off indeed. I can't get any help here for this kind of abuse, so I ask you again personally to quit this barrage of misinformation about my position... and express yourself in your own threads. I'm not giving you any abuse - I'm just asking you questions to try to pin down what it is you believe in so that I can show you exactly where you're wrong. Your problem is that you don't like being backed into a corner, and that's exactly where you now find yourself. Your theory is indeed OGVT, and that's just the old "realism" with a mistake in it which held sway until MM shattered it.
127
« on: 29/11/2012 21:17:27 »
Please elaborate. Picture a treadmill a hundred metres long (meaning that there's a little bit over 200m of track in a loop). If you run along that track while it's switched off, it takes you ten seconds to cover the distance because you're a good runner with an added superpower: you can accelerate from zero to full speed instantly like a photon, though I suspect that photons are already moving at c even before they're emitted. If the machine is now switched on so that the track is moving towards you as you run along it, and the speed of the track is half of your running speed, what will that do to your time? It will clearly take you 20 seconds instead of 10. If you then run back along it in the other direction it will take you 6.67 seconds. Now repeat that, but get a bunch of friends to do it with you, setting off at one-second intervals. You'll find that they also arrive at the finish at one-second intervals and that they pass any marker at the side of the track (not on the track, but stationary beside it) at one-second intervals. All the detectors in your experiment with light would measure your light pulses as having the same duration for the same reason. Now think about the distribution of the people running on the track. When they're going against the movement of the track, they'll be closer together, but when the track's going the same way they are, they'll be further apart. This is equivalent to the peaks and troughs of the waves of light in your experiment - the wavelength of the light is changed, except it's more complicated as the timers are slowed down and the wavelength is affected by that too (because the track represents a fabric of space through which the timers would also be moving). If you try to measure the frequency of the light, you will normally do so using something which is moving through space at the same speed as the emitter and reflector, so they detect the same wavelength regardless of which way the light comes towards them. You can only measure the true wavelengths of the light if you use a detector attached to the track (which means stationary in the fabric of space). When you're working with space though, you can't detect the track or tell which way it's moving relative to you, and because all your measuring equipment is governed by the speed of light, everything is slowed down by movement in such a way as to maintain the undetectability of the fabric of space so that you can't tell if you're moving through it, or how fast, or in which direction.
128
« on: 28/11/2012 23:53:28 »
D.C.:
" Well, if you aren't actually interested in OGVT, stop telling us it's right."
"OGVT" is your acronym. My "search" in this forum failed to find your first reference, spelling it out. Google just gave "OutGoing Verification Trunk." (?) OGVT = Old Guy's Vacuum Theory. I thought you'd understood that the first time. Me:
" I am interested in debunking large scale (not subatomic) length contraction," ...
You:
"Which means that Either you want to junk OGVT in favour of something like LET, or you adopt something like SR."
Huh? It means that the constant speed of light as per SR, which is well documented, does not automatically require that physical objects actually contract in length. You may be interested in debunking it, but you won't be able to, so your interest should then drive you into taking up a position which actually fits the known facts. The train thought experiment, if you worked your way through it, would show up the necessity of actual length contraction in OGVT/LET type theories with a 3D space and it would force you into a Spacetime model if you want to retain the idea that length contraction is merely apparent (with as a side effect the necessity to do all sorts of strange things to time which I suspect you won't approve of). As said in my other (locked) length contraction thread, the "warning" on convex mirrors is applicable to the concept of length contraction. "Warning: Objects may appear closer than they are!" The LC version would be: "Warning: Objects approaching at very high velocity may appear shorter than they are!" Okay, but so far as I can see that's going to force you into an SR camp. As I understand your usage of "LET" the Lorentz "camp" says that physical objects do physically contract. I say that would require force to crush the object or compact the distance between the atoms of such objects. You've had this explained to you many times - the forces that are already applying between atoms (and other particles) have increased communication distances to cover if the object of which they are a part is moving, and that automatically causes them to settle closer together as the object moves more quickly through space. I've illustrated this in several different ways, but you don't appear to have understood any of them so there isn't a lot more that can be done there. SR claims that all frames are equally valid and that length is not invariant. Realism, my take, disagrees. Physical objects have inherent, intrinsic properties, including length, which do not change with the various frames from which they are observed. This repeats what I have said many times, because you still show no sign of understanding my argument. In SR, lengths of things vary as you switch between 3D frames of reference. They do not change at all, however, within 4D Spacetime. SR is 4D Spacetime and it doesn't matter what people say about how things appear within 3D frames of reference, it's a 4D theory which offers you a lot of what you're after. My own opinion is that the people in the camp within SR who think things are physically changed in shape by observing them from different frames of reference are wrong because they don't actually understand SR. You:
"GR is the best reason for taking SR seriously, so I don't know why you'd want to ditch that."
I accept that the math/model of GR improves upon Newtonian prediction of the effects of gravity. I deny that this requires insistence that "mass curves spacetime" (curves what?) and that the resulting "curved spacetime" guides masses in their curved paths. (Again, repeated many times... all lost on you.) I can assure you that everything that's being lost here is being lost in the other direction, but I can predict with considerable confidence now that you'll never realise that. I wanted you to answer directly, truthfully, as you understand the answer.
If length contraction is "apparent and not actual" (as I see it), then the "contracted" arm of the MM apparatus is "apparent, not actual." Yet you constantly cite it as proof of actual length contraction. Don't get the theories mixed up. MM requires actual length contraction in an OGVT/LET type of theory. The alternative is that it requires you to use a 4D Spacetime model. If you have always accepted 4D Spacetime, then OGVT is the wrong name for what I thought was your theory of realism - I thought at that time that you rejected Spacetime, but now you're maybe happy to have it so long as you deny that it has any fabric to it. Btw and finally, I find your mock post of my position, signed "O.G." very offensive, as follows:
Hi,
I'm a believer in SR but not GR. I believe that length contractions are apparent and not actual - they merely show up as length contractions when you convert a 4D object into 3D space. I have a beef to pick with people who believe in SR but who think that objects change their actual shape as you view them from different frames of reference.
O.G. I have explained many times which parts of both SR and GR I reject, and which parts I accept. No such thing as a "4D object." All space and objects in it (not just lines and planes) are 3D (length, width & height) and as 3D objects move through space, "time elapses." My intention was not to mock you in any way - I'm trying to help you state your position clearly so that it's possible for people to work out what you're on about. After 12 pages of this, it's still vague in a number of absolutely critical places. It's really quite simple to state your position, but you are clearly not willing to do so because it will trap you in a position that can be directly shown to be wrong, so you play games instead where you keep it all vague enough that you can slide around whenever you're pressed. It's like trying to pick a really awkward piece of soap out of the bath.
129
« on: 28/11/2012 23:08:24 »
Initial thoughts:-
I've read through this three times now and haven't found anything that my limited knowledge has been able to take issue with, though I'm still a long way from understanding it all. It's written clearly and looks as if further readings of it should open it up further, so I will keep rereading it to try to fit all the pieces together better in my mind and to work out what's missing. I certainly like this mechanistic approach - someone's got to hit the right solution some day, and it's just possible that this is it. Am I missing something obvious? Has anyone with a better (or inferior) understanding of physics spotted a fault that can help break this open?
130
« on: 28/11/2012 20:11:29 »
If the measured time duration of the light pulse IS the same for both directions, the speed of light IS the same for both directions. If the measured time duration of the light pulse is NOT the same for both directions, the speed of light is NOT the same for both directions. Asserting that again doesn't make it true. If the speed of light is faster in one direction than the other, it will have a longer wavelength going one way than the other, but the duration of the pulse will be exactly the same. You need to switch to trying to measure the wavelength of the light, but you can't do that unless you can introduce a stationary detector into the experiment, which could be done by luck, but you wouldn't be able to tell if it is stationary.
131
« on: 27/11/2012 21:38:54 »
D.C.:
"If you reject Spacetime, you clearly must be interested in other theories,..."
Don't tell me what I'm interested in! See bolded "not interested" comments in last post. Well, if you aren't actually interested in OGVT, stop telling us it's right. I am interested in debunking large scale (not subatomic) length contraction, ... Which means that Either you want to junk OGVT in favour of something like LET, or you adopt something like SR. ... and the reification of "spacetime" into a supposed entity which is curved by mass. If it were just a coordinate system/model (fine with me) GR theory would not insist that it is *something* which mass curves or that it is *something* which guides masses in their curved paths. GR is the best reason for taking SR seriously, so I don't know why you'd want to ditch that. The same argument against an actually contracted Earth diameter and contracted distances between cosmic bodies holds for a contracted arm of a physical structure like the MM experimental apparatus (or a theoretical "alien probe.") And the train thought experiment too. Are you saying now that you are in an SR camp but that you reject GR? Since you think otherwise, show me the difference, i.e., how the arm actually contracts but Earth's diameter (etc.) does not, as they all depend on the same theory and principle, i.e., that physical objects and actual distances change with how they are observed. I assume you want this answered from an SR perspective, in which case I will place myself into a camp there which says that length contraction is apparent and not actual. That is the camp within SR which makes the most sense to me, and it's the one I think you'd be most comfortable in too (as I said long ago). I suppose you don't need to accept GR if you don't want to, so if that's your position then I congratulate you on working out that that is your position. If this is the case, some real progress has been made - next time you start this argument off at a science forum you can do so in more compact style, as follows:- Hi,
I'm a believer in SR but not GR. I believe that length contractions are apparent and not actual - they merely show up as length contractions when you convert a 4D object into 3D space. I have a beef to pick with people who believe in SR but who think that objects change their actual shape as you view them from different frames of reference.
O.G. Then someone can reply thus:- Hi O.G.,
Nice to hear your point of view. Food for thought. End of thread?
132
« on: 26/11/2012 20:04:03 »
D.C.,
I am not interested in your take on other theories as I've said several times before. I am challengeing the length contraction part of SR theory, as my OP clearly stated. I am also not interested in using "spacetime" as a way to explain that length contraction is image distortion or explained by difference in appearence, though that is my argument, sans "spacetime." If you reject Spacetime, you clearly must be interested in other theories, but other theories such as OGVT do not offer you any way out of length contraction other than by being incompatible with Michelson Morley. Imatfaal, a mod representing this forum as an expert on length contraction, answered my challenge... "so that measurement (flattened shape of earth) is "equally valid""... saying, "it is completely valid." Like you, I don't think that's the best position to be in - there are other camps within SR which do not suffer from that problem. If you were in such an SR camp, you would have a good position to argue from, but if you reject Spacetime you are rejecting SR and putting yourself into a position that's worse than that of the people you're attacking. You continue to try to hijack this thread to promote your agenda about other competitive theories. Again, not interested. It is impossible to give proper answers without covering all bases. If you don't want proper answers, don't ask for them. I continue to be interested in getting an honest reply... from those here who speak for SR's version of length contraction... to the challenge of the length contracted Earth and distance to the sun. My probe & shuttle was a smaller scale example of the same principle they promote regarding those examples.
You've already had answers from them - they believe in something which appears to you and to me to be highly suspect. That is what you have discovered by asking your questions. What is the point in continuing to ask them about this when you already know where they stand? Maybe your aim is to convert them, but I don't think they're going to shift, and particularly when they're being told they're wrong by someone whose own model can't handle Michelson Morley, because whatever may be wrong with their model, it certainly can. Also, if they ever do feel the need to shift position on this, they don't need to change their model at all but can simply shift from one philosophical camp within SR into another without it making any difference to the maths.
133
« on: 25/11/2012 20:37:26 »
I still don't understand how the length of the light pulse is going to last different amounts of time when all the components of the apparatus used in the experiment are stationary relative to each other. You're trying to measure time differences that won't exist and that shouldn't exist.
134
« on: 25/11/2012 20:27:49 »
The key words are "appear" vs "actually." Earth's diameter does not actually shrink to accomodate how the probe sees it, nor does the probe's length actually shrink to accomodate how Earth sees it in this .866c relative velocity scenario, which works both ways.
If the principle of length contraction were true, the probe would actually shrink to 10 meters when measured from Earth, approaching at .866c. But it only appeared to be 10 meters. The same holds in reverse for Earth as seen from the probe. To be consistent about length contraction, Earth would actually shrink in diameter to 4000 miles. That is blatant nonsense. You have to avoid mixing up different theories. In SR you can have a lot of what you're after with all the length contraction being apparent rather than actual. If you're prepared to adopt the Spacetime structure of reality, that's where you belong. If you don't like Spacetime though, you're left with OGVT and LET which are identical apart from the latter having objects length contract in their direction of travel such that the Michelson Morley experiment can be accounted for. In LET there are three possible realities. (1) The probe shrinks to half its length and the planet is not squished because the probe is moving and the planet is not. (2) The probe may be stationary and the planet moving, in which case the planet is squished and the probe is not length contracted. (3) Both the probe and planet are moving and both are affected by length contraction. The third of these possibilities is most likely to be the correct answer. Unlike with SR, in LET it is not the case that all of these possible descriptions are true, but there is no way to tell which of the three is correct from studying any lengths or speeds of things relative to each other. The same holds for the MM experiment, which you keep repeating as proof of length contraction. The arm in the direction of travel appears to shrink as distinct from actually shrinks as in the examples above... and in the example of the distance to the Sun, which might appear to shrink as seen from a fast fly-by frame. You are certainly entitled to make that claim if you place yourself in an SR camp. You insist on "length contraction of moving things." Do you get that everything is moving, so velocity must specify "relative to what?" Again you are entitled to make that claim if you are in an SR camp. It simply doesn't apply to LET, and it isn't clear that it applies to OGVT either because that seems to have a 3D space instead of 4D Spacetime. So Earth is moving at .866c relative to the probe as well as vice-versa. Do you or do you not think that its diameter actually contracts to 4000 miles in that case? A direct answer would be refreshing. I can not get one one from JP, and zordim seems to be living in a universe of his own creation. SR gives the appearance of contraction without requiring there to be any actual contraction. LET does not require the Earth to be contracted unless the Earth is moving through space. Because the Earth goes round the sun and the sun goes round in the galaxy, the Earth must be moving most of the time and will therefore be length contracted a little, but it isn't impossible that the galaxy (and all the others we can see) are moving at 0.866c and so all the stars and planets we can see could actually be squished to half their maximum width in the direction of travel - that would be highly unlikely, but it's impossible to tell that this is not the case. It would be fairly safe, however, to assume that they are not moving at all fast and are therefore not contracted to any great extent and that as a consequence any objects which are moving at very high speeds relative to us are going to be significantly length contracted (e.g. your alien probe), but that cannot be guaranteed to be true. You want a definitive answer, but none is available: there is always going to be an "if". If Spacetime is the correct model, then length contraction can be apparent and everything is stationary and everything is moving, et cetera. If Spacetime is not correct, then LET (or varients of) would be the only game in town, in which case we absolutely do have actual length contraction but can't tell what is contracted and what isn't because we can't determine whether any specific thing is moving or not. We have been over this many times. Indeed we have, and it was all answered right at the start. The answers haven't changed along the way, and they won't change unless we can get some new knowledge about the nature of reality either through scientific discovery or logical reasoning (though the latter doesn't seem to get a lot of respect from the scientific side who pick and choose bits of reasoning to fit in with what they already believe).
135
« on: 23/11/2012 22:56:20 »
The bay IS 10 meters long. The probe IS 20 meters long. All "appearences" aside, the probe will not fit in the bay, and it will not "actually" change lengths. All "appearences" aside, Earth's diameter IS and stays nearly 8000 miles regardless of how it might "appear" to a fast moving traveler. And the probe IS and stays 20 meters long regardless of how it appears from Earth.
Do both of you (zordim and D.C.) understand this? How about you, JP.
What you're saying can be true with the Spacetime of SR, but if you reject Spacetime you're going to have to have actual, real, genuine, absolute length contraction of moving things. Without it, your theory conflicts with Michelson Morley.
136
« on: 22/11/2012 21:14:29 »
The probe is shortened to 10m and when the shuttle tries to capture it after accelerating to the same speed, the probe is too big for it as the shuttle bay is now contracted to 5m. If you send a bigger shuttle instead having anticipated that the shuttle will shrink to half its length, you can send one with a 20m bay to collect the probe and that will shrink to the required 10m length when actually collecting it. As it decelerates with the probe inside it, both expand together until they end up at 20m long.
We know that these length contractions happen because of the Michelson Morley experiment.
From the frame of reference of the probe while it is moving at 0.866c, the Earth appears to have been squished to 4000 miles wide. If the Earth is actually moving and the probe is stationary, the Earth really has been squished and the probe is not lengh compressed. The complication only comes into it with SR where all frames of reference are claimed to be equally valid, but switching which frame you analyse things from does not require anyone to think that it physically changes the diameter or length of anything, even if many people in the SR camp think they change - it simply changes the way things appear to be. The non-Euclidian 4D Spacetime stuff is hard to picture, but I've been told by an expert elsewhere that it's Lorentz invarient - I take this to mean that when you accelerate things within it they do not change shape at all and that it is only when we try to convert things from there into the 3D way that we ordinarily see the universe that all these length contractions are introduced. I may be misunderstanding that though.
137
« on: 22/11/2012 20:46:50 »
Yes Carbon fibre can shatter, but what is it you are photographing that puts the tripod (and presumably the camera and photographer) at that sort of risk?!?
I suppose it may be useful to be able to fend off a dog with it on occasions.
138
« on: 21/11/2012 21:07:43 »
If you only need to reduce camera shake rather then doing long exposures, a piece of string can be a lightweight option: a loop of it round your foot, the other end attached to the camera, then pull upwards on the camera slightly and most of the shake will be eliminated. Probably not so useful now though if your camera has image stabilisation, but maybe it would still improve it with telephotos.
139
« on: 20/11/2012 21:35:39 »
If the speed of light is different in different directions, there is no way to measure that as you can't time it usefully over a one way trip. The duration of a pulse of light will be the same whether the speed of light is identical in both directions or radically different. Imagine two runners covering a course at the same speed, but not starting together. The first runner leaves ten seconds before the other and arrives at the finish line ten seconds before the other. Now turn the track into a moving one so that the runners have to run further or less far in order to get from the start to the finish and it makes absolutely no difference to the time interval between them either at the start or at the finish. The physical length of your light pulse also has no impact on the timings.
140
« on: 19/11/2012 01:06:48 »
I may have missed the point, but it sounds as if you're sending out a pulse of light and timing the length of that pulse rather than the time it takes to travel anywhere. If that is indeed what you're doing, it will be the same time interval whether measured at the source on emission, at the mirror on reflection, and on detection back at the source. I can't see how you're going to get any useful information out of that.
141
« on: 14/11/2012 21:30:08 »
Same for the distance to the sun. Never mind that Earth would be incinerated if it were actually a small fraction of the established average of 93 million miles or so from the Sun. You're displaying your lack of understanding again there: if it's squished, it's because it's moving, and if it's moving, the light and heat will be concentrated forwards in the direction of travel, the result being the approximately same amount of heat and light reaching the Earth at all times (assuming the orbit is approximately circular from the solar system's own frame of reference). Same applies to the "altered realities" of what D.C. calls LET. He says that the space between atoms in Earth varies with changes in velocity (of Earth relative to near 'c' travelers), thus giving it a 1000 mile diameter in the extreme case. More total nonsense. The Michelson Morley experiment disagrees with you. Things are length contracted in their direction of travel. It's important though that you should understand that things are only length contracted where the separation of their components is strongly locked together by forces. If you had two objects a mile apart and accelerated them both to 0.866c with one following behind the other, they would remain a mile apart without the distance between them being length contracted to half a mile. A train a mile long, on the other hand, would be length contracted to half a mile long. The contraction is the direct result of the interaction of forces or communications between the components which are slowed down by the added communication distances. In the first case we have two objects which are not locked together and which therefore maintain their separation at one mile - they are not making any adjustments on the basis of communications with each other. It's this case where there is no length contraction which led to the old assumption that things maintain their length at any speed, but when they are locked together through forces (as is the case with the MM apparatus and with the solar system), they have to contract in their direction of travel. Edit: Actually, the solar system isn't locked that way, but if it formed while moving at high speed the orbits of the planets would automatically end up being length contracted in the direction of travel because of the way they form out of a dust ring which in the frame of reference of the solar system is circular. In SR you must have the same situation with length contraction only applying to things that are locked together by forces, so if you imagine a train one lightyear long and stretching from one star to another, if it was suddenly accelerated to 0.866c it would not suddenly become half the length with the front or back end halfway between the two stars or with one end quarter of the way from one star to the other and the other end three quarters of the way. No, what would happen is that the train would break up into pieces spread across the whole distance between the two stars and with gaps here and there, the length of the gaps adding up to half a lightyear. Late edit regarding D.C.'s last post: It is trivial and irrelevant whether "LET" is a "camp" within SR. Hardly: LET = OGVT with added recognition of length contraction. SR is 4D Spacetime. Earth's diameter does not actually change as its image is viewed from various frames of reference. Correct. That is the point which D.C. is trying to obfuscate here with his pet project, promoting "LET." Cor-wrong. I'm simply waiting with interest to see how long it takes you to realise that OGVT and LET are the same theory, but with the latter recognising the necessity of length contraction while the former ignores the experiment which shows that length contraction actually happens in the real universe. Why he doesn't promote it in his own thread, I do not know. I'm much more interested in studying how people think than in promoting anything.
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« on: 14/11/2012 20:53:15 »
I've tried it on a couple of machines now and all it does is play music to a black screen. Maybe the Mac version's better.
143
« on: 13/11/2012 00:45:55 »
http://gamelab.mit.edu/games/a-slower-speed-of-light/You may have seen a little film many months ago which showed some of the warping visual effects of moving at high speed through space, but now there's a computer game available from MIT which does a similar thing, but slowing down the speed of light until it's no faster than walking speed (though it doesn't slow you down with it in the way that a reduced speed of light would really act - if you did it for real you wouldn't notice any difference but would simply live, move and think in slow motion in an equally slow-motion world). Anyway, it sounds and looks interesting judging by the trailer, and you can download the actual game for free, so it may be fun to try. It's just under 100MB. Assuming my connection holds up for long enough to download this, I'll comment on it again once I've actually tried it out, though previous experience of games suggests that my low-spec machine may only manage two frames per second. Edit: actually it looks as if I'll have to borrow someone else's machine to run it on, and upgrade it to 2GB of RAM as well, so I'll probably have to put it on the shelf for now, figuratively speaking. At least the download's finished though, so I'll get a go at it some day. Edit 2: WARNING - if you do try it out, click the little box next to the word "windowed" to run it in a window so that you can shut it down easily. If you don't do this it takes over the whole screen and you probably won't be able to find a way out of it unless you know about the Ctrl+Shift+Esc combination (which brings up the task manager and lets you shut applications down from the outside).
144
« on: 12/11/2012 23:55:37 »
Throughout this thread I have agrued against the length contraction insistence that physical objects actually change shapes/lengths with differences in frames of reference from which they are observed. SR claims that "length is not invarient," i.e., denies that Earth (etc.) has an intrinsic property of diameter length, i.e., insisting that it IS flattened, as above, not just "appears flattened," based on the dictums, "length is not invarient" and "there is no preferred frame of reference." I've made this case many times and it is you who do not yet get it. That is just the view of one camp within SR. It is perfectly possible to have a view within SR that the shape of an object does not actually change and that the true shape is seen when stationary or moving with the object. It doesn't matter how many of the people within SR don't agree with that, it is still a viewpoint from within SR. Don't attribute it to SR as a whole - you are only attacking one camp within SR. As above. I am not interested in your LET "camp" because it insists that physical objects actually do change shapes/lengths as their velocities change.
Now that's a strange reply! LET is not a camp within SR. Maybe you were writing in a hurry again and didn't have time to check and edit. ...you're putting yourself in a position which either requires you to be wrong, to be in the LET camp (which you aren't interested in and don't understand), or to have an alternative theory...
See above re your misconception, which I bolded.
You clearly don't understand it because you never get the point that things are length contracted in LET without adding any crushing force. "My theory" is none of the above, mainstream SR or LET as you have presented it with objects physically changing with changes in velocity... and it is not "my theory." It is realism, which you do not understand, though I've explained it many times. The "elephant" has its own intrinsic shape as a real animal/object, independent of how it is observed. If you accellerate the elephant to .866c, it will not shrink to half its tail-to-trunk length. An "elephant compactor" would be required for that, and that would definitely kill the elepant. And there we see again that you don't understand LET. Let me just walk you through a little of the history. Up to about a century ago, your theory was the only game in town. The Michelson Morley experiment then disproved it. Lorentz managed to recover the situation by working out how objects automatically become length-contracted in the direction of travel, so he created an improved version of Realism which corrected an incorrect assumption of the earlier kind of Realism. Einstein then came up with another kind of Realism which turned time into a dimension and so far as I know it is only LET and SR that can handle the Michelson Morley experiment - the older version or Realism clashed with it. Now, if there is another theory which can account for the results of MM, I'd like to see it. So far as I can tell, you're just pushing the old, broken version of Realism. If you don't like the idea of Spacetime, the only place you'll find where you've still got a leg to stand on is going to be LET. The advantage that SR has over LET is that GR can be built upon it to provide a startlingly accurate way of calculating the effects of gravity, but that doesn't mean that it's right - I suspect it's just tapping into something which could be accounted for in some other way, but that's another discussion. What matters is that there are two theories which can handle MM, and both of them are well worth getting your head around. If there's a viable third option, I want to get my head round it too because it may be the piece that unlocks the puzzle. I don't believe that you've got a viable third theory though: it looks exactly like the old, broken Realism to me, and the mistakes you keep making confirm that. That paragraph was important - don't skip it. All the camps in SR (and LET) require you to build a >20m long container to hold a 20m long object when they are moving/stationary together. Length contraction only comes into it when calculating interactions between things that are moving relative to each other, so your signature example isn't addressing that issue.
My example addresses the SR claim that the probe is contracted to 10 meters as measured from Earth. It is not, and it doesn't grow twice as long after the shuttle enters its frame.
Ironically, you'd only have a vestage of a case if you were in a Realism camp within SR, using the nature of Spacetime to avoid the length contraction being real. You don't like Spacetime though, which leaves you with a straight choice between the old and new Realisms of OGVT and LET (V standing for vacuum). Without Spacetime complicating the issue, we can now state categorically that when the platform is stationary within the vacuum and the train is moving past at 0.866c, the train is length contracted to half its rest length, and this can be demonstrated by sending light along it as set out a few posts back (in the thought experiment which you're too scared to explore). If you don't like that, then you can jump into an SR camp and use Spacetime to escape from the clutches of LET. I don't care which way you jump, but I would like to see you make the leap of understanding necessary to recognise that you're standing in a position which is not viable. OGVT should make the train travel twice as far as it does in reality before the light from the back has reached the front. That is where OGVT falls.
145
« on: 10/11/2012 23:09:38 »
Here again is the essence of my argument against length contraction:
"In the real world,(neither) observation (nor measurement from different frames) is a force which changes physical things." That is not an argument against length contraction: it's a argument for (or against, depending on whether the brackets are there or not) the idea that observation changes things physically. It is ironic that denying that Earth changes shapes/diameters, as observed from different frames, is now considered a "new theory" not to be taken seriously, because it denies that Earth's diameter contracts, as SR insists. Don't attribute it to SR as a whole - you are only attacking one camp within SR. This basic embrace of a "real physical Planet Earth" with intrinsic properties (size and shape) independent of how it is observed (not changing with changes in how it is observed) is still my answer to D.C."s query:
Fine, but I'm still trying to find out why/whether you think you aren't in an SR camp.
But I've said this dozens of times... yet you ask the above. SR says that reality depends on how it is observed, that there is no "real, unchanging Earth." They say that "for" a frame of reference flying by at near 'c', Earth is flattened, i.e., contracted in diameter. Re-read the thread if you have forgotten all the insistence by length contraction advocates that earth does change shape with changes in frame from which it might be measured. Again you're attacking SR as a whole rather than just the specific camp within SR which holds that view. There are other ways of looking at things within SR where there is no physical change made to the thing being observed, and you may find that you belong there. So long as you keep attacking SR instead of finding out whether you fit within an SR camp, you're putting yourself in a position which either requires you to be wrong, to be in the LET camp (which you aren't interested in and don't understand), or to have an alternative theory which you aren't prepared to set out clearly enough to demonstrate that it isn't wrong. You've been doing this for eleven pages now in this thread and still haven't made your position clear. What makes you think you aren't in a mainstream SR camp which doesn't insist on things being physically changed by being observed from different frames? The reason I use this as my signature example is because it is so obviously a denial of reality by SR. But the same principle applies to rulers, trains, the MM apparatus arms, my shuttle and probe... and the distance to the sun... which if severely "contracted" would result in Earth's incineration (as a "flattened" Earth would also be destroyed.)
meters long, not 10, will be required. All the camps in SR (and LET) require you to build a >20m long container to hold a 20m long object when they are moving/stationary together. Length contraction only comes into it when calculating interactions between things that are moving relative to each other, so your signature example isn't addressing that issue.
146
« on: 08/11/2012 21:05:23 »
You still claim to know me and my motivations better than I know myself and my reason, as above. If you agree that that different observations do not create different realities (lengths of objects, etc.), then seeing the same object differently does not make it change. Your train does not get shorter with differing observations of it. The details are then moot. I'm still trying to get you to explain your exact position - it isn't yet clear what you believe based on your attacks on length contraction. I've tried to make it easy for you by pointing to two theories and two interpretations of one of them in the hope that you'll either pin yourself to one of them or put forward a clear fourth alternative which doesn't go against the results of experiments. It still looks as if you could fit into one of the camps within SR, and yet you repeatedly appear to reject that. If you answered the train questions it would maybe help to clear that up. It is perfectly possible to say that the metre-long train when moving at 0.866c fits into a space 50cm long while still remaining one metre long in its own frame where its true length is to be found. SR theory does not maintain that change of speed physically compacts an object, as a bullet compacts to shorter when fired. I'm not clear as to your meaning there in relation to the bullet being made shorter. I can see three different ways in which the bullet length contracts: if it's soft enough, it could be slightly crushed by the force applied to it (that crushing remaining as the bullet slows down); it will have compression waves sent through it (but would rapidly bounce back from those to recover its full length shortly after leaving the gun); and it may be length contracted for relativistic reasons. I suspect the bullet is strong enough not to be crushed, so it's probably only affected by two of these kinds of contraction. It is always, "For observer A," moving relative to an object, it IS shorter than "for observer B," at rest with the object. SR theory (which is the focus of my argument!) does not claim that application of force compacts the object to make it shorter. And, further, physical objects are not shrunken to shorter by the 'power of observation', which is not a force that can change physical objects. That is fine - it is clearly a problem for one camp within SR if they imagine that things are physically changed by being viewed from different frames. You've missed out the Michelson Morley experiment - the one which disproves your "realism".
No. It still depends on the usual "for observer A" vs "for observer B" definition of changing "reality." Again, the reality of physical objects (the length of the apparatus arms here) is not altered by differences in observation. That is idealism, not realism. (See the Wiki definition above... again.)
You seem to be positioning yourself in one of the main SR camps there. If that's the case, then you simply need to accept length contraction as a phenomenon relating to the effective lengths of things in different frames. If that is your position, I don't know why you haven't made it clear that that was your position from the start. You are wrong. The machines are built to apply immense force to accellerate minute particles. In the process, they are observed to be flattened in the direction they are traveling. Denying that doesn't help your argument. They are accelerated up to speed gradually and any compression from that acceleration is thrown off almost as soon as it is added. Even if they were accelerated in an instant, the resulting compression would be thrown off again a moment later. Length contraction is a totally different thing from compression, and you're mixing up the two. No force is likewise applied to Earth, yet mainstream SR (my focus here!) claims that "for an observer" traveling past at near 'c', it is pancaked in diameter in the direction of the observer's travel. It doesn't work. It has a load of false assumptions which do not transfer from the empirical observation of contraction of particles with applied force in an accelerator. If you accept the length contraction of particles in an accelerator, you have to accept it in relation to the Earth too because it is not a different phenomenon. To avoid contradiction, you really ought to be denying that particles are length contracted in an accelerator because they are not compressed into a pancake shape by acceleration forces. The MM apparatus was built with arms of equal length. Seeing one arm as shorter under no circumstance makes the actual physical arm shorter. You've made another assertion which goes against LET. If you don't intend your assertion to apply universally but are restricting it to SR, then for one camp within SR that is fine: the arm is effectively shorter in other frames, but not actually shorter. Yet again, regarding my "alien probe retrieval project," you say:
If you're trying to measure length contraction using a ruler which has been length contracted by its movement, you're on a fool's errand.
You are stuck in the belief that physical objects change length when they move relative to an observer... the essence of SR's length contraction. The shuttle bay was built and remained 10 meters long, even when it joined the probe's frame and *appeared contracted* to 5 meters. The probe was built and remained 20 meters long, even as it approached Earth at .866c and *appeared* 10 meters long. As said above, the shuttle's launch and change of velocity relative to Earth did not make it shorter, "in the real world" even though it appeared to shrink as it joined the probes frame. Your experiment is an attempt to prove that length contraction isn't real, but it tries to do that by accelerating a ruler up to the same speed as the thing it's going to measure, at which point any length contraction which has been applied to the thing being measured will also have been applied to the thing doing the measuring, rendering the experiment pointless. I repeat, my argument here is with mainstream SR's version of length contraction as advocated by the authorities of this forum, in which there is no force applied to objects to compact/contract them. There is no force applied to Earth to flatten it, but the fly-by guy "sees" it as flattened, and there is no preferred frame, so a flattened Earth is equally valid, they say. I am not interested in what you say about LET. Movement doesn't make objects contract. Only the image of objects gets distorted. They still don't understand the difference. If you are actually in a camp within SR and not writing off length contraction altogether, then I prefer your position to theirs. They don't actually agree that a force needs to be applied to length contract anything, so I'm guessing they see it more in the way of multiple realities all being true at the same time, and that's a kind of thinking encouraged by some interpretations of quantum mechanics. That is why their position isn't as mad as it may initially seem - it's just a different approach. You:
...LET uses existing forces within the object to contract it simply by maintaining the balance of forces between atoms.
Nonsense! "Maintaining the balance of forces between atoms" will maintain the object's shape and length. To change an object's shape/length, a force must be applied to change the space between whaterver units, molecules or atoms, of which the object is composed. Existing forces acting all the time between atoms will do the job automatically. Think about this illustration of how it works. Imagine two people who decide to maintain their distance from each other by shouting across a field, each one shouting back to the other as soon as they've heard the other one shout to them. They continually adjust their positions to try to keep the round trip of the sound to a fixed interval of time. On a windy day, they will automatically end up closer together than on a still day because of the extra distance the sound has to travel through the air, and the exact distance between them will vary in direct response to the speed of the wind. If the wind is moving at 86.6% the speed of sound, they would need to stand twice as close together as they do on a still day if their clocks were also affected by the wind speed, but because their clocks are actually governed by the speed of light they will instead end up standing four times as close together as on a still day. (Ignore the impossibility of standing up in such a strong wind.) That is how it works in LET: the forces between atoms are actively maintaining the distances between them all the time, and normally that means the distances are constant, but if you move the body of which they are part at high speed through the vacuum, this slows down the communications of these forces between the atoms and results automatically in them settling closer together in their direction of travel. That is why no additional force need be applied, other than to accelerate the body to higher speed. The clue to the fact that no lasting compression has been added is the fact that if you then spin the body the length contraction remains in the direction of travel at all times. That happens to spinning particles in an accelerator too - the pancaking is always in the direction of travel, whereas a crushed bullet if it started to tumble would have that compression rotate along with the bullet. You also need to understand that the acceleration of particles in an accelerator is done as much by pulling them as by pushing, so if you're imagining them being squashed by pushing forces you're getting a warped view of things. Even if all the force was applied by pulling the particles up to speed though, they would still length contract and not be pulled out into long strings. "...because LET is realism."
Nonsense, as exposed above. You really don't understand realism. Objects remain as they were formed or built until a force is applied to crush or compact them to a shorter length or to way out of spherical shape, in Earth's case. LET and SR are both developments of realism: they have taken length contraction onboard in different ways, and in different ways within SR too. Anything which hasn't taken length contraction into account is not realism. In the real world, observation is not a force which changes physical things. That is my argument, and I've said all I have to say about your argument... yet again... hopefully. Fine, but I'm still trying to find out why/whether you think you aren't in an SR camp. Again, carry on with your LET argument in a thread of your own. I only bring LET into it when it is necessary. Your lack of interest in it doesn't give you the right to ban it being mentioned when you make absolute pronouncements which conflict with it.
147
« on: 07/11/2012 20:17:44 »
Markus has hit the nail on the head with his point about dumbing down. The Naked Scientists show is serious science put across in an intelligent package in the same way that Tomorrow's World used to do things (in the pre-Vorderman era which turned it into soppy slodge). Now it seems that everything covering science or technology has to have presenters who act as if they're making a programme for children, and moronic children at that. (Well, either that or it has to have lots of scenery in it and a dishy presenter who has to pose as a god, making even the shallowest pronouncements sound profound. I like Brian Cox, but not the style of science program he normally does - you can occasionally get a glimpse of the real Brian when he appears on The Sky at Night.)
I suspect that the way science is taught in schools has a very negative effect, killing children's interest in it by turning everything into a deeply boring chore - science is too important to ram it down people's throats in the way they do. This leads to TV programmes feeling the need to take a custard-pie-in-the-face or blow-the-lot-up approach to the subject in a desperate attempt to rekindle people's interest in something they have come to associate with high pressure exams of the kind obsessed with soon-to-be-forgotten facts instead of actual understanding.
Maybe you need to go with the flow and get some pop stars on the show to talk about a science story that interests them - one such item per show. The thought doesn't immediately appeal to me, but a lot of pop stars have hidden depths and you can find some intelligent life amongst them (e.g. Brian Cox and Brian May).
148
« on: 06/11/2012 22:15:03 »
David,
I did not take your test because different observations do not make things change in length. Given that, your "test" is irrelevant. You didn't answer the two simple questions and the other question which required a little bit of maths because you know that it would destroy your position whether you got it right or wrong. That's why you'll never answer it, but you'll find an infinite supply of flimsy excuses instead, starting with this:- You said that you agree, as follows:
Me:
The operative phrase in length contraction is always some version of "for observer A vs for observer B... the length is measured to be different."
Realism insists that the objects themselves do not change even if observed/measured to change. Observers seeing an object differently does not mean that the same object actually changes. You:
I have always agreed with you on that. You contradict yourself. I agree with the bit about observers seeing an object differently not changing the object. I assumed that was what you were talking about throughout the whole bit there, but if you're actually intending part of it to mean that the change in an object caused by its change of speed doesn't change the object, then I don't agree with that part. There are no experiments showing length contraction outside of particle accelerators. You've missed out the Michelson Morley experiment - the one which disproves your "realism". There, subatomic particles are flattened ("pancaked") by overwhelming application of force accelerating them. The pancaking has nothing whatsoever to do with acceleration forces on them - that is a complete misunderstanding of the physics on your part. It doesn't work with Planet Earth, distance to the Sun, or rigid objects on the scale of the examples discussed in this thread. The "contraction", for instance of one arm of the MM apparatus, depends on differences in observation (frame of reference). See again what you agreed to above. You misunderstood what I was agreeing to: I was only agreeing to the part about the same thing being observed by different observers as having different dimensions not making any change to that object - their contradictory measurements cannot both be correct when it comes to the actual shape of the object. The shuttle bay was built on Earth to be 10 meters long. It stays 10 meters long, even when it is traveling beside the probe, the bay now appearing 5 meters long from Earth. The probe was built 20 meters long, which is why it appears from Earth contracted to 10 meters because of its velocity relative to Earth. The shuttle when at rest with the probe sees it as it is, 20 meters. It is twice as long as the bay. Neither the probe nor the bay changed lengths.
Only appearences changed, (called length contraction) due to changes in relative velocity. You still don't get it. If you're trying to measure length contraction using a ruler which has been length contracted by its movement, you're on a fool's errand. Me:
"(Force is required to actually change the shape or length of a physical object, and length contraction posits no such applied force.)"
You:
"Repeating that over and over again doesn't make it true. The first bit is true,..."
You agree that "force is required to actually change the shape or length of a physical object" ("the first bit"), yet you say that repeating it doesn't make it true, implying that it is false. More self contradiction. Again no contradiction. If you want to change the actual length, forces will be involved in that, but there is no extra compression force added to the mix for this - the forces which contract an object are the same ones which set the distances between its atoms all the time whether it's stationary, moving, accelerating or decelerating. The full quote should be:- The first bit is true, but in some interpretations of SR the shape isn't really changed, while in LET is isn't changed by observation but by movement through space, and the only forces required for the contraction are in action all the time (whether the thing's moving or not). That's fully clear and fully correct. It is true, and of course repeating it doesn't make it more true. You're attacking a straw man - SR doesn't need the contraction to be real, and LET uses existing forces within the object to contract it simply by maintaining the balance of forces between atoms. Different observations do not make the same object change lengths. Believing that reality changes with observation is idealism, not realism. Agreed. "For observer A", Earth, the probe appears to be 10 meters. "For observer B" (shuttle at rest with probe) the probe is as it is, 20 meters. It didn't actually ("really") change lengths during the shuttle's mission to capture it.
Do you get it yet? You're the only one who hasn't got it. In LET it really did change length. In SR, it changed it's alignment in spacetime and hid some of its length in the time dimension. I am not interested in debating the alternative theory you call LET.
Start your own thread and make your argument there. Every time you attack "length contraction theory", you're attacking LET. If you restrict yourself to attacking the camp within SR which you have an issue with, I won't have to keep setting the record straight, though you'll also have to stop laying claim to realism, because LET is realism.
149
« on: 05/11/2012 20:06:11 »
I take it the test questions were too hard for you, seeing as you don't even mention them. I suspect everyone else who has taken part in this thread is capable of answering them correctly, but the person who has the most need to do so is you because you are trying to lay down the law to everyone on what reality is despite not having a proper grasp of the maths of length contraction and why it is necessary for realism to take it into account. David Cooper:
And no: you are not a realist. Realism requires you to take length contraction on board in order to account for the results of actual experiments which show your "realism" to be wrong, but you refuse to do that. Yet again... Wiki:
"Realism... the belief that reality exists independent of observers." That poses no problem for me, but it does for you because experiments show that length contraction is part of reality. "Observers" include frames of reference as used in the context of lenght contraction.
In other words, realism denies that different observations of the same object or distance (from different frames of reference) reflect real differences in those objects and distances. Realism is fully compatible with LET, and also with some interpretations of SR. It is not compatible though with a model which excludes length contraction altogether. (Force is required to actually change the shape or length of a physical object, and length contraction posits no such applied force.) Repeating that over and over again doesn't make it true. The first bit is true, but in some interpretations of SR the shape isn't really changed, while in LET is isn't changed by observation but by movement through space, and the only forces required for the contraction are in action all the time (whether the thing's moving or not). This is quite obvious in the case of Earth's diameter and distance to the sun, neither of which actually contract, even if they could be observed to contract from extreme relativistic frames. In LET it could be contracted without you knowing it, so there's nothing obvious about it. The same principle holds for other supposedly "contracted" objects like my "probe"* or arms of the MM apparatus, or your train. When you think the train's moving at 0.866c it could actually be stationary for all you know, so you have no idea how long it really is. * It was measured from Earth to be 10 meters, approaching at .866c, but at as the shuttle pulls alongside to capture it, it is seen as it is... 20 meters long, twice as long as the shuttle bay. You never did get that one, an expose of... a reality check on... the length contraction fallacy. If the shuttle is moving with the probe, it is length contracted to 5 metres while the probe remains contracted to 10m. You appear to be the only person here who doesn't "get" your own thought experiment. The operative phrase in length contraction is always some version of "for observer A vs for observer B... the length is measured to be different."
Realism insists that the objects themselves do not change even if observed/measured to change. Observers seeing an object differently does not mean that the same object actually changes. I have always agreed with you on that. Yet we have length contraction "theory" insisting that an Earth with a 1000 mile diameter is equally accurate ("no preferred frame") with the "real animal" which is nearly spherical with a nearly 8000 mile diameter. No, we have one interpretation of SR insisting on that and you are right to attack it. Another interpretation of SR is close to your position, regarding the true shape of an object as the one you see when you are moving/stationary with it. In LET (which you presumably include in "length contraction theory") there is no measurement you can point to and claim to be the true one unless you have access to knowledge which is currently not available by any known method. The same principle holds for "length contracted trains" and the MM apparatus arms. Are you claiming they don't contract then? Surely you can answer this simple question without doing any maths. No, David, different observations do not create different lengths for the same object. How can you think you're disagreeing with me on that? The "No" at the start of that should be a "yes".
150
« on: 02/11/2012 21:22:46 »
So I ask the forum (whomever might be still be reading this thread), do you agree with the following, a recent summary statement I made here:
The job of science is to study and accurately describe things as they are, not to re-create them as subjective versions of an infinite number of "realities" depending on who is looking at what from whatever different frame of reference. ... as length contraction theory does. Here it is again in a nutshell... anyone...:
The job of science is to study and accurately describe things as they are, not to re-create them as subjective versions of an infinite number of "realities" depending on who is looking at what from whatever different frame of reference. If you don't mean anyone, don't make it such an open invitation. You're acting as if no one's answered your questions, but they've all been answered repeatedly. Time and time again you simply write off all their replies as if they were worthless and return to where you started, implying that no one has even addressed the issue. This is deeply insulting to everyone here who has tried their best to engage with you. As expected, you've ignored my invitation for you to show off your understanding of the whole business of length contraction by discussing the train thought experiment, choosing instead to repeat a whole bunch of assertions which are just the same old attack on "length contraction theory" and the beliefs of many people within the SR camp who are comfortable with contradictions. Everyone has got that last point: some people are happy with contradictions in theories while others aren't: we established that this is the case long ago. And no: you are not a realist. Realism requires you to take length contraction on board in order to account for the results of actual experiments which show your "realism" to be wrong, but you refuse to do that. This is the key point where your position is wrong, so why don't you give it a shot and try to demonstrate that you are actually qualified to push your assertions by picking apart the train experiment to show that it doesn't need to be contracted to half its normal length when moving at 0.866c. If you can't rattle off a sufficiently detailed analysis of that in twenty minutes or so, you shouldn't be firing off all your guns here. Do you need more help with it? Shall I do 90% of the work for you to make it easier? Let's make it a toy train so that it's only a metre long. We've got a mirror sitting on the top of the train at the back and another at the front, one metre apart if the train's at rest. "Now, hold on a minute!" I hear you say: "There's going to be an alignment problem with the mirrors when they're moving, so they won't reflect the light in the right directions." That's a really good point you make (which only an expert like yourself would spot), so let's instead try to keep the beam on a straight path throughout to eliminate the problem. We can put the source of our light beam over the track slightly higher than the train and send out a pulse of light exactly as the back of the train passes underneath. Further up the track we can have a detector, and what we want to do is get the light to hit that detector at the same moment as the front of the train passes underneath. How far away from the source is the front of the train when the light is emitted? Is it one metre, or half a metre?. How far from the source is the back of the train when the light hits the sensor? Is it one metre, or half a metre? How far away from the source is the detector going to be placed? I'm not even going to give you a choice for this one - you're going to have to prove that you can actually do the necessary maths. So, the challenge is set right there for you. Stop messing everyone around and provide us with some hard answers to demonstrate that you are actually sufficiently qualified to make your assertions and to ignore everything everyone else says. You're calling on the mods to get rid of me. I'm calling on you to show them that they shouldn't get rid of you.
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