Existence

You have an unjustifiably high opinion of your posts here. You don't understand even the simplest points under discussion, yet you are hosting a classroom in physics? Your entire post is is replete with evidence that you don't even know what reference frame is. You cannot apply postulate #2 correctly, because doing so requires that you understand inertial reference frames.I disagree with you because you display little more than the physics knowledge we were all born with. I've taken the trouble to learn considerably more than that. No it does not. Every event in space-time exists in every reference frame, so merely identifying an event does not identify a
reference frame.Of course none of that has the least chance of get through your iridium skull? This is at least the dozenth time I've attempted to explain reference frames to you. We can discuss the coordinates of points in space that are located inside the car using any reference frame we choose. We can discuss the coordinates of points located outside of the car using a reference frame whose origin is inside the car. No it does not mean that, ICANT. The actual situation should be quite simple to visualize even for you.In the car frame of reference, the emission point is fixed in time and space, the car and blackboard are at rest, and the photon travels four feet between the emission point and the blackboard. Is that understandable? You don't have to agree, just accept that such is my position.In the track frame of reference, the emission point again is fixed in time and space, while the car and blackboard move along the tracks at 0.5c. Ignoring time dilation, the photon moves 4 feet in a direction perpendicular to the tracks while concurrently moving 2 feet parallel to the tracks (a total distance of 4.47 feet) before striking the blackboard.Yes the description of distances and times is different as measured in the two different reference frames. But so what? What is important is that the laws of physics including the speed of light be the same in both reference frames.There is absolutely nothing inconsistent with my position. In a given reference frame (inertial or not), the space-time coordinates of the photon emission point do not change. The values of the coordinates may be different in different inertial reference frames.Nothing particularly special about what I've said. The same thing is true for the coordinates in space-time of any event.Edited by NoNukes, : Add more about space-time events.

Big deal. If you can convince me I'm wrong, I'll change my mind.

Unless your program is capable of displaying reference frames that are in motion relative to each other, and I do not know why an Architect program would need such a capability, you are not using a tool capable of providing an accurate picture.Besides, none of us are describing light paths that are not straight lines. When you talk about straight lines, do you mean only lines that are at right angles to the tracks?And what sense does this make "I was beginning to believe you was right". I've never said anything to the contrary.

Hi NoNukes, I thought all inertial reference frames were frames of reference that were in motion at a constant speed, relative to other frames of reference. I thought you could choose any reference frame to be at rest.I did not know you could declare them stationary and they would cease their motion at a constant speed.

quote:

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All inertial frames are in a state of constant, rectilinear motion with respect to one another; they are not accelerating

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SourceIs all inertial frames in a state of constant motion in a straight line as stated in the above reference?If so which one can be stationary?Is there anything in the universe stationary?I believe that there is.I do understand that when you add "relative to" you can declare frames of reference at rest relative to other frames of reference. But declaring a frame of reference at rest does not make that frame of reference stationary, as it does not cease it's motion at a constant speed.Such as the laser pen is attached to the car and is stationary relative to the car.The blackboard is attached to the car and is stationary relative to the car.But under no circumstances I see, can you say the car can be stationary relative to the point the photon is emitted from the laser pen.The car is in motion at a constant speed of 0.5 c relative to the coordinant point in space the photon was emitted from the laser pen.That coordinate point in space remains motionless in space regardless of what the car, the earth or anything else in the universe does.God Bless,

Why would it need to? It is just as correct to say that the car is stationary and the tracks are moving.Why would the photon need to follow the motion of the tracks in a stationary car? What is it about the motion of the tracks that changes the trajectory of the photon? Where did anyone claim that the light would travel at a velocity different than c? It does go in a straight line, the straight line connecting the point of emission with the center of the target. In the car's frame of reference, the point of emission and the end of the pen laser are one in the same at all time points. The pen laser is directly pointed at the center of the target at all time points. So why shouldn't the photon hit the target? Why does the velocity of the track relative to the car matter?

You pick an observer that is not accelerating, and then determine what is or isn't stationary relative to that observer. That is how inertial frames work. Is there a golden point in the universe to which everything else has to be compared? No, there isn't. All inertial frames are equivalent. Therefore, you should observe the same path for the photon in the car's inertial frame no matter how fast it is moving relative to the tracks. That is what postulate #2 states. Sure you can. The pen laser never moves in that inertial frame. Therefore, the end of the pen laser and the point of emission are one in the same within that inertial frame. It doesn't matter how fast the car is moving relative to the tracks. This remains true within the car's inertial frame. The only way that they could not be the same is if the car is accelerating, or if the pen laser moves relative to the car during the transit of the photon. False. Coordinate points are determined by the observer's inertial frame. Therefore, if you are in the car's inertial frame the point of emission does not move. It is the tracks that are moving, not the point of emission.

Since you believe in an absolute frame of reference, it means that you actually disagree with relativity. Of course, you have already been proven wrong by experiment (Michelson—Morley).
Link: Michelson—Morley experiment - Wikipedia

Yes, and we can identify any inertial reference frame as the stationary frame. Normally we pick a single reference frame based solely on convenience and consider objects at rest in that frame to be stationary. I don't understand why that creates some problem for you.There is no preferred rest frame. You can identify any inertial reference frame as the rest frame, because the laws of physics including the speed of light in a vacuum are the same in any inertial frame.You seem to be looking for a way to be right about the word "stationary" having no meaning. I don't think that is a worthwhile endeavor. Nonsense. I do understand your confusion, but you are wrong. I'll explain.Let's place the laser pen at the spatial origin of the car inertial reference frame, and let the time that the photon is emitted from the laser pen be t = 0 nanoseconds. The coordinates of the photon at time of emission are then 0, 0, 0, t=0 in the car frame of reference.In the car reference frame, emitting end of the laser pen never moves spatially. It remains exactly where it was (spatial coordinates 0,0,0 in the car frame of reference) when the photon was emitted. In fact, in our thought experiment, the only object within the car that moves in the car frame of reference is the photon.So (using the car inertial reference frame) every point on the car is always the same spacial distance from the emission point of the photon. Thus the photon emission point does not move in the car frame of reference. And stating the obvious the car does not move in the car frame of reference.In the track frame of reference, the laser emission point will always be over the same slat on the rails now and forever. So in that sense, the laser emission point does not move. However in this frame of reference the car does indeed move at 0.5c along the tracks. So in the track frame of reference the car does indeed move away from the emission point at 0.5c. As a matter of fact you are wrong. There is no frame of absolute rest, and we always assign velocities to objects (other than photons) based on an adopted stationary reference frame. It is our choice of stationary or rest frame that defines which objects are at rest, which objects are moving, and the rate of velocity of the moving objects.For example, we say that a parked car is moving at 0 mph despite the fact that the rotation of the earth can cause the ground to move at 1000 mph near the equator. We intuitively choose our reference frame to be the street when we are talking about cars.However it might be useful in some problems to acknowledge that the car is moving at 1000 mph due to the rotation of the earth. For example if I was launching a missile at the car from the north pole, I'd need to take into account that the 1000mph relative motion between me and the equator.Back to the emission point.The space-time coordinates of the point of emission have a fixed value in every reference frame (inertial or not), but the fixed value is different in every reference frame. But there is no point of absolute rest anywhere in the universe.Again most of this is basic stuff that has been understood since the time of Galileo. If you think it is fodder for debate, then you aren't up to discussion the physics of time.

Hi NoNukes, It does not need such a capability it just has a 3d module that can make all kinds of moving things.I can do a tour of a house I have drawn at any stage of the drawing whether it be footer, finish, or anything in between. I can also do a tour of the yard with all the landscaping. It is just a fun thing that can be used to show the client what their new home will look like when finished. I have stated over and over that the laser pen is mounted at a 90 angle to the motion of the car. That is the same as the tracks. So the photon would travel at a 90 angle relative to the tracks as well as the motion of the car.This would be the same regardless of the speed of motion the car was traveling at.Straight lines can be a straight line between any two points regardless of what direction they are going.But in this thought experiment I am specifically speaking of a photon being emitted from a laser pen at a coordinate point in the space of the car.That laser pen is pointed at a detector or blackboard which ever you want to call it on the opposite side of the car.If the car was moving at 0 speed relative to the tracks the photon would hit the detector every time the laser pen emitted the photon. The movement of the earth would be less than the width of a human hair in the time it takes for the photon to travel the 4 feet from the laser pen to the detector and thus would not effect the photon hitting the detector.When the car is accelerated to 0.5 c constant speed nothing has changed about the installation of the laser pen and the detector.The laser pen is pointed directly at the detector at all times.The problem arises when the photon is emitted from the end of the laser pen.If that photon travels in a straight line from the coordinate point the photon is emitted from the laser pen it will miss the detector.The only way the photon can hit the detector is for it to move 2 feet in the direction the car is traveling at 0.5 c as it takes that long for the photon to travel the 4 feet to the opposite side of the car.Since the car is traveling at 0.5 c relative to the coordinate point the laser pen emitted the photon it will miss the detector.You and others are trying to convince me that the photon will travel 2 feet in the direction of the motion of the car and hit the detector.How can that be reconciled with the statement "independent of the motion of the emitter"?Light must be propragated at c in a vacuum independent of the motion of the emitter.The photon can not add the forward motion of the car and move the 2 feet required for the photon to hit the detector without some force being applied to the photon.That is why in the cycle light clock I installed the tube to force the photon to travel the .5 meter distance the cycle traveled as the pulse traveled from the bottom mirror to the top mirror. That was the only way I could force the pulse to hit the top mirror.That is why I keep making the statement that the photon would have to have an unbalanced force applied to cause it to travel the 2 feet forward to hit the detector.Somebody mentioned bouncing the photon off a mirror.If we were to install a mirror between the two sides of the car that the photon would hit and change the direction of the photon, with proper placement of the mirror we could cause the photon to hit the detector.God Bless,

Hi Taq, The car is stationary relative to what?The car is traveling at a constant speed of 0.5 c relative to the tracks and the coordinate point in space that the photon is emitted from the laser pen.When you declare the car's reference frame at rest the car does not stop its constant motion of 0.5 c speed relative to the tracks and the coordinate point in space that the photon is emitted from the laser pen.So at no time is the car stationary. Even when the car is doing 0 mph relative to the tracks it is still doing 1000 mph relative to the center of the Earth. I never claimed anyone did.I did state and claim you are dismissing the last part of postulate #2."independent of the motion of the emitter".You are adding the forward motion of the emitter to the horozontal motion of the photon to cause it to strike the detector which is false.The photon can not add the forward motion of the car, emitter, or detector to its horozontal motion and postulate #2 be true.I am stating I believe postulate #2 to be true but you are declaring it to be false. But that is not a straight line in the direction the photon is traveling in when emitted from the laser pen. And that is precisely why the photon can not hit the detector after traveling 4 feet because the detector has moved 2 feet relative to the coordinate point in space the photon was emitted from the laser pen. It doesn't.The only velocity realtive to the photon that matters is the car's constant motion at 0.5 c relative to the coordinate point in space that the photon is emitted from the laser pen.The photon moving in a straight line in the direction it was emitted from the laser pen will miss the detector.Now if I wanted to hit the detector every time the photon was emitted from the laser pen I would mount the laser pen at a 26.57 angle relative to the motion of the car.But then unless the car was in constant motion at 0.5 c relative to the coordinate point the photon was emitted from the laser pen the photon would miss the detector.God Bless,

We're not declaring the car's reference frame to be at rest. The car's reference frame is the frame in which all other velocities are measured relative to the car. This is high school physics.

Hi Taq, I actually thought all inertial reference frames were in motion at a constant velocity relative to all other inertial reference frames.

quote:

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All inertial frames are in a state of constant, rectilinear motion with respect to one another; they are not accelerating

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SourceDo you disagree with the above statement?That says all inertial reference frames are moving and nothing about one of them being stationary or being able to declared stationary and cause them to cease their constant straight line motion relative to one another. Where did I mention anything about the laser pen moving or not moving.I said the car is moving at a constant 0.5 c relative to the coordinate point the laser pen was at when the photon was emitted from the laser pen.That point does not move ever, as it is just a coordinate point in space. The inertial frame the laser pen is in attached to the car is moving at a constant 0.5 c relative to all other inertial reference frames.The coordinate point in space the photon was emitted is not moving in that inertial reference frame, and neither is the photon. The photon is traveling in an overlaping reference frame toward the opposite side of the car from which it was emitted from the laser pen as the car travels at a constant speed of 0.5 c. I thought I said the point of emission does not ever move.But that does not stop the car's traveling at a constant 0.5 c speed, relative to all other inertial reference frames.God Bless,

You don't notice anything particularly irrelevant about your response?You have not described any capability for your program to show the path of moving objects from different inertial reference frames. So why should any of us be surprised when your tool does not verify what we are telling you about trajectory angles in inertial reference frames? Yes, and I agree that you've described things as measured in at least one reference frame.I don't care what prediction you make about which reference frame. If you say that the photon misses the detector, we can build on the assumption that your prediction is correct.In order to demonstrate the effect of special relativity, however, we need to demonstrate the ramifications of your prediction in two different inertial reference frames.It is at this point that you begin to flake out. You've use various tactics to avoid such an analysis. I'll list a few along with my impressions of them.1) ICANT denies that a driver in the car can see the chain of events.Me. But so what? We can still calculate the coordinates of the events in the observers reference frame, and the coordinates are what we use to do physics. What can be seen is irrelevant.2) ICANT denies that an enclosed frame moving at constant velocity is an inertial frame and then makes up some forces.Me. Nonsense. All frames in which Newton's laws hold true are inertial reference frames. Enclosed frames work the same as open frames.3) ICANT: L'il Architect program does not show different trajectory anglesBy your own admission L'il Architect is not capable of modeling the problem.4) ICANT I don't know what postulate #2 really means because I don't know what "As measured in any reference frame" means, but I'm sure that it proves Einstein is wrong.Me: Einstein's coordinate transform and velocity combination equations are derived from postulates #1 and #2 and thus must be consistent with the postulates. Accordingly, you cannot use the postulates to prove that length contraction and time dilation are not real. Let's discuss what postulate #2 really says.5) I don't care what the math says, what other physicist say. I'm right because...Me: Uh, I'm ready to summarize.Okay, back to your questions. As if we had not explained this dozens of times.As measured in any inertial reference frame. Let's not forget that supremely important part of postulate #2. Let's also note that the postulate only requires that the velocity of light be "c" as measured in any inertial reference frame and independent of the motion of the source. So the path of the light can change as long as the velocity is still "c" regardless of the motion of the source.Of course none of that explanation is anything new to you. I suspect that the I can now answer all of your questions using only references to my own prior messages.

Take reference frames A, B and C.
Frame A is moving at +15 m/s. Frame B is moving at +45 m/s parallel to frame A. Frame C is moving at -45 m/s parallel to frame A.
Frame B's velocity relative to A is +30 m/s.
Frame C's velocity relative to A is -60m/s.this is high school physics.

Seriously, ICANT, are you really that stupid?? We explained to you many times already, NoNukes even linked to some neat illustrations about inertial frames. When will you decide to learn instead of talking out of your ass? What part of relative=/= absolute don't you understand? You truly have a knowledge of physics straight from the Dark Ages. Are all creationnists as ignorant as you are?I won't try to teach you high school physics anymore, it's just hopeless and your mistakes are getting sillier as the thread goes on. I guess I should save them for when I intend to argue that a creationnist education makes you ignorant.