Existence

Really? Here's an experiment you can do at home: point your laser pen at a mirror.

Actually, light is like everything else in this regard. The path of any moving object is different as measured in different reference frames.

Hi Son, This is just a wild guess but you can correct me where it is wrong.You are sitting on a bench waiting for a bus to come.I come around the cornor and into your view and as I come down the street and stop at the red light in the intersection next to the bench you are sitting on.I have entered a reference frame where you can observe me in my car.The light changes and I head down the street, you can still observe me in my car as I get caught by the next red light one block away.I make a right turn and head down the street at a right angle to where you are sitting. Just as soon as I get behind the building on the corner you can no longer see me in my car.I have now left the frame of reference you are able to observe.If I am not mistaken I have entered a reference frame where you could observe me in my car and left that reference frame. Now if you want to drop the word reference frame in which you observe me in my car and use the term coordinate system. You can still find and pinpoint my location in relation to your location.But you can't observe me in my car.God Bless,

Hi ICANT Surely you jest.No ICANT. We are not going to redefine reference frame just so you can be correct about something. A reference frame extends just as far as does the coordinate system that characterizes said reference frame. The coordinate system is a mathematical tool for describing locations and events.It is as I suggested earlier. You think a reference frame means what you can see from a view point. Well, you are absolutely wrong. Reference frames are of infinite extent. You yourself believe that a light frame can extend for a light year. See above. Your wrong about nearly everything.We've explained reference frames, provided videos on the topic, and you yourself have cited definitions, most of which match what we are saying. Yet you still don't get it. I'm wondering why I should bother making yet another presentation on the topic. There are countless explanations of the topic on the internet.You are free to pick a new term like "sight" or "view point" to describe what you can see. But what can be seen is not an important limitation. If an object has coordinates in a reference frame, then we can talk about the physics of that object using the reference frame. It is the physics of the object that must comply with postulates #1 and #2 not just what is not hidden by buildings or lying behind the milk in the refrigeration.

I can accept that I'm technically incorrect there, but riddle me this, batman:A bowling ball would not take the same path as a photon, right? (from the reference frame on the ground as the emitter is flying by)

Hi NoNukes, Lets examine:The car is on a track attached to the Salt Lake Flats.The car has a frame attached to the rear that has a laser pen mounted 4 feet from the ground at the top, pointed toward the ground at a 90 angle to the motion of the car on the track that is attached to the Salt Lake Flats.Now as long as that car is on the tracks fastened to the Salt Lake Flats with the laser pen fastened to the frame on the back of the car pointed at the ground at a 90 relative to the travel of the car the pulse will hit the ground everytime it is emitted.In the real world this is a fact.So what in your world would cause the pulse to not hit the ground? You have now gone back to the experiment where the laser pen is mounted through the roof of the car.But no the laser pen mounted through the roof of the car is not like me using my laser pen in a powrpoint presentation.The laser pen is mounted through the roof at a 90 angle relative to the travel of the car. It can not change it's direction. It will always be at a 90 angle relative to the travel of the car until manually removed and the hole drilled at a different angle, and then remounted. Simple:The one you just brought back up the detector and the laser pen are in the same inertial reference frame.The pen is mounted throught the roof of the car at a 90 angle relative to the motion of the car over the tracks on the Salt Lake Flats.The detector is mounted on a 4 foot pole attached to the roof of the car 1 inch from the point the laser pen is flush with the exterior of the roof of the car.If the car is doing zero mph relative to the tracks mounted on the Salt Lake Flats the pulse will hit the detector everytime a pulse is emitted from the laser pen.If the car is traveling at 0.5 c relative to the tracks mounted on the Salt Lake Flats the pulse will miss the detector as the detector will have moved 2 feet relative to the point the pulse was emitted relative to the tracks.Therefore if the pulse travels in a straight line from the point emitted at c the pulse will miss the detector by over 1 foot. I await your presentation. If the blackboard is in the car the laser pen would operate the same as it does in a classroom.Lets set the stage for this experiment if the blackboard is on the Salt Lake Flats.The 4 x 8 blackboard is mounted at a 90 angle relative to the Salt Lake Flats parallel to the tracks, 25 feet from the tracks.There is a trip switch on the tracks the car is traveling on, mounted so it forms a 90 angle at the front end of the blackboard.The laser pen is mounted in the side of the car at a 90 angle to the travel of the car and a 90 angle relative to the Salt Lake Flats.When the car hits the switch a signal is sent which takes 3 nanoseconds to cause a short pulse to be emitted from the laser pen.I believe that according to postulate #1 which requires the pulse to travel in a straight line from the time emitted, the pulse will hit the blackboard.According to what you have been trying to convince me of the pulse will miss the blackboard as the pulse has to travel at an angle like it does in the stupid light clock with moving mirrors presented.Which would meant the pulse would reach the distance the blackboard is from the tracks after the laser pen has moved 12.5 feet from the point the pulse was emitted. That means the pulse would miss the blackboard by more than 4 feet.But yes I would not observe whether the pulse hit the blackboard or missed it as I would be 26+ feet past the point the pulse hits the blackboard when the image of the pulse reaches me. I would be traveling at 0.5 c, which would make a small pulse of light very hard to see.But if it were possible to see the pulse hit the blackboard I would observe the pulse to hit the blackboard after I had traveled 26+ feet from the point the pulse was emitted.So yes it would be behind me when it hit the blackboard. I will agree that at the moment the pulse would hit the blackboard the laser pen is aimed at a point that is 12.5 feet further down the track than that point.

p = point laser pen pointed
e = emitted
pb = point on blackboard laser pen pointed pulse hits
s = position laser pen is when pulse hits blackboard
eb = end of blackboard

pb        eb     p
|          ^     |
|                |
|                |
|                |
|                |
e                s  

So which is it, where will the pulse go from the time it is emitted at e?Will the pulse hit the blackboard or miss the blackboard?God Bless,

You are wrong in such a silly way I'm beginning to wonder if you even passed middle school, unless your schools had far lower standards than mine had....A reference frame is a coordinates system with an origin that is usually chosen to be a rest in relation to an object chosen depending on the problem. As long as I can describe an object's coordinates in a reference frame, this object is "in" this reference frame (meaning that short of stopping existing, an object will always be in every frame of reference).I just can't understand where in hell you thought sight had anything to do with it when the definitions of a reference frame make no mentions of it. Edited by Son, : No reason given.

Hi crash, OK.My hand was kinda shakey trying to hold the laser pen pointed at a specific spot on the mirror so I improvised.I took a small table and placed it before the wall mirror and took a vise from the shop and attached it to the table. I then put the laser pen in the vise aimed at the mirror. I thought the light was hitting the same spot everytime I pressed button on the side.But to make sure I had my wife hold the button down and I painted the spot on the mirror black. Then I tried again and everytime I pressed the button the light hit the black spot on the mirror confirming my statement that the pulse will hit the spot it is aimed at when the pulse is emitted from the laser pen.So what was you expecting me to see?God Bless,

Hi CS, Let me take a crack at this and if I am wrong NoNukes can correct me.If we were to modify the car where you could be standing and you were to throw a 10 lb bowling ball from the car the bowling ball would go at an angle relative to the track and would land farther down the track relative to where the ball was released relative to the position of the car on the track.The reason for that is that the bowling ball would take on the forward motion of the car.The photon can not assume the forward motion of the car thus it has to travel in a straight line from the point emitted from the laser pen.God Bless,

Hi Son, Stupid me. Maybe I got the idea because we were talking about observational frames or reference.

quote:

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A frame of reference in physics, may refer to a coordinate system or set of axes within which to measure the position, orientation, and other properties of objects in it, or it may refer to an observational reference frame tied to the state of motion of an observer. It may also refer to both an observational reference frame and an attached coordinate system as a unit.

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SourceThat says an observational reference frame is tied to the motion of an observer.I get the idea that means someone is observing something taking place.God Bless,

Well, first there's this "or" meaning it could be either, but even then "observer" doesn't exactly mean in physics what it usually mean for the layman. Have you ever seen a physic problem using reference frame and being preoccupied with line of sights?If you interpretation of what was a reference frame was, planes, Gps and whole host of things that require reference frames to use wouldn't work while there were clouds because they couldn't "see" the other points from their "reference frame". Since there's no daily crashes due to clouds, we can only deduce your definition is completely stupid.Tell me, what use would be a reference frame in physics if it was limited by your line of sight? Do objects behave differently when we can't see them anymore? If not, why does it matter whether you can see the objects or not?Edited by Son, : No reason given.

So you're starting to get that photons don't behave like bowling balls...Where this gets interesting is that light always has the same speed no matter what reference frame you measuring it from. Be it in the car or on the salt flats. So when you observe a photon emmited towards the detector as the car is flying by you, from your refence it will travel a longer path than from the reference frame in the car (cause it'll look like its going at an angle rather than straight perpendicular, here's a diagram: Still with me?If you do that with a bowling ball, then to you its going to look like the bowling ball is moving faster because its traveling a greater distance in the same amount of time.With a photon, the distance is still going to look greater, but the photon will look like its going the same speed (cause it can only go that one speed). So how can it go a greater distance at the same speed in the same amount of time?Something has to change, right?Velocity is distance over time: So if v remains contant and D increases, then t must also increase. That is time-dilation.

HI ICANT "Stupid light clock" eh? Well, light clocks are inanimate objects. I assume stupid refers to me.You've made a bad guess at what my position is. What I'm telling you is that angles for particle trajectories are different when measured in different reference frames. The difference is not an optical illusion, the actual angles associated with the same trajectory trajectory are different.Let's look at a portion of your latest thought experiment. You seem to be unaware that you've just made my case regarding the angles measured in different inertial reference frames.According to your own description, you have aimed the laser pen at a ninety degree angle to the direction of motion of the car, yet you claim that we will miss a spot on the blackboard that is located at a 90 degree angle from said direction as observed and measured in the car reference frame.The laser pen holding dude can verify the 90 angle by tapping the blackboard with a long rod directly right before firing the laser. The rod touch will confirm that some spot on the blackboard is directly across from the laser holder, but according to you, the fired photon will still miss the entire blackboard. The miss is completely inconsistent with a 90 angle for the photon path as verified by the rod touch. If the photon misses, then the angle traveled by the photon as measured in the car frame of reference cannot possibly be a right angle. Period.The above is exactly the point I've tried to get into your mind in most of my posts this week. Even when I agree to ICANT's own prediction about where the laser beam hits, ICANT's own description of events requires that the angles measured in the two different reference frames be the completely different. That's why I don't spend a lot of energy debating hits or misses with you. It is the geometry of the results that betrays you.On the other hand, if you agree that the photon does strike the blackboard, then the angle as measured in the track frame of reference cannot possibly be 90 degrees.

And what spot was that? Was the spot directly in a straight line with the direction the pen was pointed, or was it in fact somewhere on the wall behind you?

You are correct.Even if the paths of the bowling ball and the photon overlapped in one frame, the paths would (as you correctly surmised) appear quite different in another inertial frame.