Existence

Hi ICANT,The following statements of yours kept rattling around in my head so I took a second look at them. If you press and release the button on the side of the light pen in one microsecond, a feat that I know that humans are not capable of, you will generate a "pulse" of light about 1000 feet long. No you cannot change the trajectory of a beam of light. When you point the laser in a new direction, you send brand new photons in that new direction. The old ones continue to act just like the ones making up what you are calling a pulse. There is no sense in which the photons traveling in the new direction are part of the same "beam" as those traveling in the first direction. Your definitions are pure hogwash.

Hi ICANT,I believe your reading comprehension skills could use some honing. Perhaps spending some restful time with the family is in order.In the following excerpt, emphasis is added by me. Do you see the disconnect between what Taq said (correctly) and your attempted rebuttal?In short, Taq says that the guys' motion relative to the ground is at right angles to the path of the ball. That is certainly true. You respond by denying that the ball travels at right angles to the ground's motion.I plan to post a list of things that ought not to be said about reference frames along with an explanation of why those things make no sense. The above exchange won't make the list, but you'll likely see some familiar stuff. Really? How high did Taq say that hot air balloon was flying?If the observer thought that the boys were rolling the ball on the ground, that would make no difference with regards to Taq's point, so why even bother to say it?

Hi ICANT and fellow physics enthusiasts! I have to admit that trifling responses of the type above annoy me. Taq asked for a diagram of events as they occur in the driver's frame of reference. Taq did not ask for a drawing of what the driver could see from his vantage point in the car. Yet ICANT, in typical fashion insists on denying that the driver can see anything and refuses to answer the question.In fact, if we ignore the effects of special relativity, there is a very simply mathematically relationship the coordinate systems of the two inertial reference frames involved in this problem. We can exploit that relationship to show what happens in one of the inertial reference frames given the knowledge of what happened in another inertial reference frame. The equation works even if the observer's view is blocked. Taq's question can be answered regardless of what a driver in the car can see. Does anyone seriously think a different set of events occurs when the driver turns his back on the action?The diagram below illustrates the relationship between the relevant coordinate axes. In the above drawing, the red coordinate axes represent the salt flat's coordinate system, with O representing the origin of the salt flat's coordinate system. The blue coordinate axes represent the position of the car coordinate system at time = t. At time = 0, the origins of the O and O' axes would have coincided. However, the origin O' moves to the right relative to the O origin at a velocity V. So at time t, the separation between the O origin and the O' axis is V*t as shown in the drawing. Each coordinate system has a third axis Z, which is perpendicular to the axes shown. In the case of this problem, nothing interesting occurs in the Z axis, and the Z axes are not shown.The black dot represents an event in space at time t. The coordinate axes for each frame extend to infinity. Accordingly the event has coordinates in both coordinate systems. In fact every possible event that has or will occur has coordinates in every coordinate systems regardless of whether that frame is inertial or non-inertial. Statements like "particle X has left coordinate system O' and is in its own coordinate system are clearly seen to be without meaning." Particle X has coordinates in every reference frame. A photon outside of a car has coordinates in the car reference frame.The horizontal coordinate for the event in the O' frame is X', while the horizontal coordinate for the event in the O frame is X. It should also be clear from the drawing that X' = X - V*t'. On the other hand the vertical coordinate for the event is the same in the two coordinate systems.Using these equations,Y' = Y
X' = X-V*tallows us to calculate the coordinates of events in the O' frame whenever we know the time and location of the events in the O frame. People familiar with physics will recognize the equations above as the Galilean transform equations. The equations do not take into account any aspect, whatsoever, of special relativity.Let's apply the equations to the problem Taq asked ICANT to solve. Let's even use ICANTs version of how events occur in the salt flat frame (O). The velocity V for this problem is 0.5c. ICANT says the the photon travels vertically from point E to point D. I presume that this occurs at the speed of light, although that scarcely matters. Accordingly, the coordinates and times for point E and D are as follows.For the O frame
E 0 feet horizontal, 4 feet high at time 0.00 nanoseconds
D 0 feet horizontal, 0 feet high at time 4.0668 nanosecondsWe now have all of the information we need to calculate what the coordinates in the O' reference frame. Note that the vertical (y) coordinates are the same in both reference frames.X' at time zero = 0 - 0.5c * 0 = 0 feet
X' at time 4.0668 = 0 - 0.5c * (4.0669 nanosecs) * 186,282 miles/sec * 5280 feet/mile = -2 feetFor the O' frame.
E 0 feet horizontal, 4 feet high at time 0.0
D -2 feet horizontal, 0 feet high at time 4.0669 nanosecondsSo we arrive at a familiar answer once again. In order to provide the answer requested by Taq (well at least an ICANTized version of that answer), let's plot those coordinates on the O' axes. Note the complete lack of any mirrors in the diagram. ABE:Exercise for the intuitive student: Where would the location of sensor S be on the above diagram.Edited by NoNukes, : No reason given.Edited by NoNukes, : Grrr... Fix plot of point D.Edited by NoNukes, : No reason given.

Hi ICANT.Congrats on making post #1000. That is not "The" question. It is one of several questions.As I've demonstrated in detail, the answer depends on the frame in which the aiming is done. In my opinion, the set up of the thought experiment suggests that the laser was aimed vertically in the car frame of reference. You disagree.Not only do you disagree, you don't even understand what a frame of reference is, which makes discussing them with you incredibly difficult if not impossible.The answer to my question is that sensor S would be at the origin of coordinate system O' at time 4.00669 nanoseconds. I've already answered your question about where the photon would strike. Ignoring SR effects, the photon would strike S under my understanding of the problem, and D under your understanding. But if we require the photon to travel at "c", neither answer is correct.But using either understanding case, the photon would not take a vertical path in one of the car and track inertial reference frames. You have yet to address any of my demonstrations that such is the case.

I don't understand this answer. I can agree that the pulse would miss both D and S, but only by taking into account SR. How does the length of the pulse establish that the pulse will miss both D and S?

The internet is fully of excellent, free reference material on relativity. I highly recommend Leonard Susskind's lecture series on Special Relativity on iTunes and Youtbe. In fact, Susskind has free semester length lectures on a wide variety of physics topics including classical mechanics, statistical mechanics, QM, string theory, general relativity and cosmology. For Quantum Mechanics I'd recommend the Oxford QM lectures on iTunes over Susskind's lectures.I've linked to Lecture 1 on special relativity. The first few minutes of Susskind's lecture 1 on special relativity cover inertial reference frames and coordinate systems. The math level escalates a bit after that. 1000 NoNukes to anyone who watches the entire 110 minutes.Edited by NoNukes, : Fix video link

I think ICANT was reacting to my discussion of his definition of a light beam. As long as the pulse is short compared to other dimensions in the problem, I don't think the difference matters. A one attometer pulse of visible light is an impossibility given that the wavelength of visible light is on the order of 10^-7 meters.

ICANT, ICANT Your drawing is incorrect. It reflects the nonexistence of your understanding of inertial reference frames exactly as do all of your posts regarding thought experiments. I've already pointed out your errors with regards to a very similar drawing. I'm not going to bother doing so again. You can read my reply in Message 992 if you are the least bit interested.I recommend that you take a look at the first few minutes of the Susskind video I've posted. It provides an excellent introduction to inertial reference frames. You don't need to accept SR to understand inertial reference frames.Or don't. I like it when you post goofy stuff. It is funnier when you maintain your current ignorance on the subject. I doubt that. You actually seem to be actively avoiding understanding. For the photon to strike point D, the photon must travel at an angle in the car frame of reference. Yet you don't see a problem with that. How do you avoid seeing a problem? By saying that the car driver did not see the event.SR requires that the speed of light be independent of the motion of the source, and that the speed of light be c as measured in any inertial frame. It actually turns out that the angle in question must be 30 and not 26.57 in order to make that all work out. But you haven't even gotten to the point of understanding the 26.5+ result yet.Assuming that the light strikes point D as you maintain, you have yet to explain events as they occur in the car reference frame. The 90 angle in the track frame means an acute angle must be produced in the car reference frame. But apparently the ability to grasp that a discrepancy even exists is beyond you. Instead you spout nonsense denials.I and others will continue to explain. I'll continue to look for alternate arguments. But I am convinced that you will never get it.

Hi ICANT, You are asking questions way over your own head.In what way is the "NoNukes" reference frame different from the salt flats reference frame.In what way is the driver's reference frame different from the car's reference frame.If those pairs of reference frames are indeed different, then how are the Earth and PlanetX frames the same reference frame when they are a light year apart?Yes, Catholic Scientist should have indicated which frame he meant was moving, but we all know very well what he means. You, on the other hand, aren't making any sense at all.Added by Edit:I wanted to add yet another recommendation regarding the Susskind lecture. I'd suggest the first 15 minutes as particularly relevant. Edited by NoNukes, : No reason given.Edited by NoNukes, : Recommend videoEdited by NoNukes, : No reason given.

Hi ICANT, I did not expect that the video would change your mind. I was hoping only that you would learn something more about the method for transforming the coordinates of events from one reference frame to another. Did you find that Susskind was wrong about one or more aspects of that topic? Were you able to appreciate that Susskind and I were telling you essentially the same thing?The bottom is that no object or photon can travel a vertical path in every possible coordinate system. That simple fact means that you are wrong when you insist that photons need "tubes" to travel at angles just because the photons path is vertical in one reference frame or another. When you deny this particular point, it is pretty clear thatI can no longer pretend to believe your denials regarding this specific point are out of honest ignorance. You simply refuse to answer questions than pin you down to providing/calculating a path for "dragged photons" in a light clock or "paths of the light beam in the car reference frame" or the path of a photon inside a flat car using the flimsiest possible excuses. Of course if you ever admit that simple fact, very little would be left to talk about.Alternatively, you could simply cite a source for your own interpretation of postulate #2. You've indicated that you could do this, but to date you have not.

As is the case for all coordinate systems, the driver's reference frame extends to infinity and includes all locations inside and outside of the car.Reference frames are not contained within other reference frames. Every event is space time has coordinates in every reference frames. So no reference frame "resides" within other reference frames. Each reference frame covers all of space.All of the above have been explained to you many times, and were evident from the presentation in the Susskind video. Why do you continue to ask questions that have no meaning at all? Yes I would, but the pointing direction would be different in different reference frame and observers at rest in other reference frames would agree that the pen points in the direction of the laser pen, despite that direction being different from the one I observer.I refer you to my demonstration in Message 1 regarding the 3 millimeter light path within the interior of the light pen. I demonstrated that the direction of the light pen was the same as the direction of the light beam.Again, your questions simply tell everyone that you don't know what a reference frame is. Angles, directions, momenta, and particle energies, are simply not consistent across different reference frames. Your insistence that they must be is wrong.But prove me wrong. Cite a reference supporting your alternative position.

Not quite.I think your answer is based on the old experiment. You are responding to a thought experiment where sensor S and detector D are both mounted on the tracks.But you are right about the central issue here. You don't need to show the interior of a car to show the driver's reference frame. A simple X/Y coordinate drawing is all that you need. You can use the same drawing to show either the car's reference frame or the driver's reference frame.

Nice deceptive job of selective quoting, ICANT. A fuller extract would have made clear that "that topic" was inertial reference frames. This is at least the third time I've caught you doing this. Presenting a quote out of context like this is not honorable behavior. Perhaps you are simply extremely negligent in a way that does not reflect yourself in an honorable light, but I no longer believe that your selective quoting is accidental.Here is a quote with more complete context.

quote:

---

As measured in any inertial frame of reference, light is always propagated in empty space with a definite velocity c that is independent of the state of motion of the emitting body.

---

Quoting this statement makes you look silly because you never apply the "As measured in any reference frame" portion of the quotation. Well it as at least some progress that you no longer try to promote that goofy interpretation of postulate #2. 1000 more NoNukes credits. Edited by NoNukes, : No reason given.

Of course not. While the statement is true, it is not a consequence of the first law, but of how laser pen's are designed.I've answered the question several times. The direction the laser pointer is pointed is not the same in the car frame of reference as it is in the salt flat's frame of reference. So it's pointless to pretend that this question leads to a confirmation of your position.I'm preparing yet another demo to illustrate frames of reference. I'm sorry for exposing you to that video that reminded you so much of your past algebra classes. That must have been painful.

Duplicate.Edited by NoNukes, : remove duplicate