Look at your post of 11:41 to refresh your memory of your introduction of the infamous "carried along" phrase. I think that the light is not going diagonally unless the laser is aimed diagonally. I think that I have asked a number of important questions and made a number of comments that you have chosen to ignore rather than to confront. I respectfully request you to addres my backlogged questions and comments before their quantity becomes hopelessly immense.
I need a post number... times are local time. Hold your mouse over the reply link, and look at the number at the end of the link shown in the status bar at the bottom of you explorer window If the camera filming the event is moving south, does the light flash appear to be going diagonally when the film is replayed? I think that all your questions are labouring undering a misinterpretation of the scenario. In the scenario, the device never moves. It is fixed to the floor. It is our viewpoint that moves.
Cangas, You may have missed [post=963092]this response[/post] to an earlier post of yours... I don't think you acknowledged or replied to it.
Pete says CANGAS is wrong, that galilean relativity and special relativity both say that the direction of travel of anything (including a light flash) is frame dependent.
I think there is a lot of confusion here about what a frame of reference is. A frame of reference is just a coordinate system. You can talk about clocks and cameras and which is moving, but an inertial frame does not have to coincide with any physical object. If you have anything move back and forth in a straight line in one coordinate system it will zigzag in another coordinate system which is moving with a constant velocity relative to the first. It has nothing to do with things getting "carried along" or with things being "aimed diagonally". It is just a mathematical substitution of variables. -Dale
No but the bullet has mass and forward momentum. I have seen some data that claims light doesn't have such lateral momentum. (Granted most says it does however).
I think some may be confused because most (all?) animations I have seen portray the observer (camera) at rest and the other frame moving. I had forgotten Pete's early statement, and different animation, that the observer is the one moving in this animation. I guess I just overlooked his statements to the contrary in regard to his animations.
No one else is commenting, so I will state the obvious: although the photon 'appears' to take a longer path in the moving frame....it doesn't. Time of travel is the same in both frames.
Last things first. Thank you Anomalous, for attempting to be helpful. The link was a nice description of radiation pressure and directly related matters. It had no relation to the point I am making, however. My point is that the motion of a photon source has no effect upon the velocity of the photon.
If that was so then why will the photon seem to be at speed of light to the source ? I wont be much help to U from your point of view but U hold too much potential for me.
Now to get started with the thread topic: A source of possible confusion is the switch from the original thread description of a pair of devices, one stationary and one moving, now changed to a pair of devices, one bolted to the floor and the other one bolted to the floor, too. Another source of possible confusion is the original thread statement of light being emitted in a Northward path and also in a Westward path ( a clear description of two light paths separated bt exactly 90 degrees ) having been changed to spherical wave fronts ( which, radiating 360 degrees, have no formal separation at all ). Having made comments based on the ORIGINAL thread statement which, in my opinion, were not responded to satisfactorily, I have persued the original statement. The intervening switches by the thread starter have made it difficult for me and others to keep track of which comments were pertinent to which of the several switches. Of course, It could not be possible that the thread starter has deliberately attempted to muddy the water for any self serving reason. At this time a question needs to be asked: If the thread has been switched to analysis of two stationary devices, and if we are correctly remembering Lorentz/SR length contraction be a result of an object moving and therefore contracting, what is the present point of this thread?
Anomalous: According to the old Emitter Theory ( or it may have been Emission Theory ), light had a velocity of c RELATIVE TO ITS SOURCE. Light had a velocity of c plus source velocity or minus source velocity, depending on the circumstances, when observed by an observer who did not share the velocity of the light source. In other words, a stationary observer looking at light emitted by a moving source would measure a light velocity higher or lower than c. Einstein and other scientists considered Emitter Theory and found several problems considered insurmountable. Einstein went on to invent Special Relativity, in which the speed of light is completely independent of the speed of its source. If the speed of emitted light is completely independent of the speed of its source, not only light emitted straight ahead or straight back must be subject to the rule, but light emitted in any direction. If light takes on the velocity of its source, suppose an object is traveling at .99999999 c relative to a stationary observer and light is emitted at a 90 degree angle to the path of the object; the light will have its usual velocity of 1.00 c in the perpendicular direction and ALSO an additional contributed velocity of .99999999c in the direction of the motion of the object, all as measured by a stationary observer. The two velocities at right angles are vector components which result in a resultant velocity, conveniently determined by, at least approximately, in this simple example, use of Pythagoras Theorem. The resultant velocity vector of the light is approximately at a diagonal angle to the path of the object and is significantly greater than c. The terrifying prospect of light traveling faster than light causes many scientists to affirm that light does not take on any of the velocity of its source. If light emitted by a moving object does not take on any of the velocity of its source, light emitted exactly sideways just keeps on going sideways and does not flip into a diagonal ( or any angle ) path with a forward component. If light does take on the velocity of its source and so light can travel faster than light, we need go no further to declare Special Relativity dead and can begin today planning a nice funeral. Or a wake; I would like Heinekin beer, please.
I hope someone someday will tell me about what thoes problems were. What made them believe its so is another big mystery. I always wondered who or what terrified them about it. For me its good news because that makes space travel more interesting.
There was never any mention by me of one device moving and one stationary. I'm sorry you misinterpreted. The notion of spherical wavefronts was incorrectly introduced by 2inquisitive. Your interpretation is One device, not two. We are examining the same set of events from two different reference frames. We are viewing exactly the same thing from two different "cameras". The point of the thread is to take the postulate that the speed of the flashes is the same in each reference frame (camera film), and see if length contraction is required.
Sideways is frame dependent, CANGAS. Sideways on the first camera's film (ie in the device's rest frame) is clearly not the same as sideways on the second film (ie in the frame which is moving south relative to the device; the frame in the which the device is (apparently) moving north). Do you think the flash is moving diagonally on the moving camera's film because it is carried along by the device? Or do you think it is because the camera is moving south?
Flash, 2inq, not photon. The path recorded on the moving camera's film is the path of the flash in the moving frame. Clearly, it is longer than the path of the flash in the rest frame. I think what you mean to say is that the longer path is not real, that the rest frame path is the real path. Right?
Interestingly, this thread seems to have become a discussion about wha a reference frame is. It is because of miscommunications that I've begun using the language of cameras and film rather than reference frames... and I think perhaps we're beginning to make progress? I think I'll use the cameras on tracks approach to reference frames more.
This is incorrect. You can determine that the path is longer by the Pythagorean theorem. Again, a frame is just a coordinate system. The length of a path is well defined in any coordinate system (by the Pythagorean theorem for a Cartesian coordinate system). There is no getting around the mathematical fact that it is a different length in the two coordinate systems. -Dale
