michel123456

This above diagram is wrong, you are mixing 2 different things. The yellow dot is light, the blue dot is not. You are making a recipe for chili with chocolate: the ingredients are wrong. ---------------------------------------- Here below a screenshot from my diagram of post #167 At this time frame, where do observer A sees the light coming from? From point B or point C ? It is difficult to explain the concept of motion without time. If you superpose all the time frames of my gif in post#167, you will obtain a regular static diagram with multiple red & black dots. My interpretation of that static diagram is that there is only one red & one black dot "moving" in the time dimension. Mass is where the dot is at the chosen time frame. You cannot choose more than one time frame "at a time" because it equals to add a time dimension which, as you said, is not consistent with physics. I thought it was easier to figure that out.

You are confused because there is only one yellow dot in the diagram. You must imagine what happens when the red dot emits continuously rays of light. That's a bit complicated to draw. Another way to represent the same phenomena consists in considering the diagonal as the simultaneity line. The good thing is then that the black dot is continuously upon the PLC, comoving with the red dot. The bad thing it that the path of the yellow dot is confusing: it is not the way light goes from the source to the observer but it is the way the observer observes things happening. (edit) It shows the line of sight, as if the observer was sending the information instead of receiving it. I am not sure it helps. I'll do that (maybe). ----------------------- That's bad, sorry. The blue dot represents the point where the observer looks at, it does not represent a ray of light. It is more a point of expansion of his observable universe.

???? there is no duplicate.

I am not sure what you mean by this. Constancy of SOL gives a relation between spatial coordinates: you cannot go from one coordinate to another at will, you have to take count of time.

I don't understand your objection. The yellow dot is the information carrier. When it reaches the red dot, the observer at this coordinate observes the black dot at the coordinates on the diagonal. For him the black dot is physically on the surface of his PLC because nothing can go faster than the yellow dot. The comoving objects in present time are not part of the physically observable reality.

Where do you encounter such a situation?

If you transform this dynamic diagram into a regular static space-time diagram, you will obtain the standard light cone described by the trajectory of the yellow dot. The black dot was observable at the intersection with the diagonal when the yellow dot reached it, and it is on the diagonal that the black dot is placed on a space-time diagram.

This is what I understand concerning 2 objects AT REST as they travel in time. The small yellow dot is a ray of light. If you could rotate the diagram 90 degrees in such a way to see the thin side of the sheet of paper, you would see a ray of light coming from the red dot (which is AT REST) to the black dot (at rest), and the labelling of time given by a clock.

I have edited my post. But their observation will be different. By definition. That's good. Yes. ??? Did I say that? If I did I apologize. It seems we have a diametrical opposite view of things. I didn't argue that. What i argue is about the conclusion we drive when looking at the diagram and putting a bunch of Marions because there are a bunch of observers. The strange notion IMHO is to believe that objects (and thus mass) are elungated in time. I didn't know I was so unique. I didn't argue that. I argued against the conclusion, see above. There is a full misunderstanding: yes both observers are correct, and they disagree on observations, by definition. When you superpose 2 different observations in the same diagram, what do you expect? Nobody argued that Marion didn't exist in the past. Nobody argued against observation of the one or the other, both are correct. Yes, you have to choose a configuration. You cannot take all configurations superposed. I agree about the misunderstanding. If I understand clearly, you say that it is incorrect to make a Mass-Space_Time diagram because it is based on a false assumption. Is that it?

I don't think so. With such a syllogism you may falsify the whole theory of relativity. Yes she can. In space it is called motion: Marion can be at 2 different coordinates in space, I hope you agree on this. What i say is simply that the same and only one Marion can be at 2 coordinates of spacetime because she "moved" from one coordinate to the other. The 2 points on the diagram cannot be interpretated as "2 marions". If you choose Marion In Black as observer, then Marion In Red is gone. If you choose Paul as observer, then Marion in Red is there and Marion in Black is not. You cannot choose al POV "at the same time" and get a safe result. The diagram gives a wrong impression because it is a mix of different observers. Each observer has its own diagram. I don't understand why it should be surprising. This is a strawman. i never argued that there is only one observer nor that there exist an ultimate "truth" connected to a single observer. Quite the contrary. IMHO the problem is not in my "model" (it is not a model, it is an interpretation). You still haven't answer clearly to the question "where is mass" in your interpretation of objects that "persist" in time. (Pause)--------------------------------------------- --------------------------------------------- ---------------------------------------------(end of pause) Diagram A (see below) is an hypothetical figure where Speed Of Light is infinite. Observation between Marion & Paul is instantanate. Their observations are reversed and mutual, there is no delay. There are 2 points called "Marion" and 2 points called "Paul", but there are no 2 Marions nor 2 Pauls. The diagram shows the translation of Marion & Paul in time. To me it is obvious like 1+1=2.(To you I see it is not) . Diagram B is what really happens, SOL is not infinite, there is a delay between observations. But there is no fundamental change with diagram A as far as the nature of Marion & Paul is concerned. Marion & Paul do not "persist" in time any more than in diagram A. Marion & Paul are not extruded in time due to the angle of SOL. The following W diagram is not what happens.

the jumping robot Sand Flea

IIRC you said that an object persist in time, I said that an object moves in time. There is a difference between our interpretations. For Marion, Paul is constantly in her past. For Paul, Marion is constantly in his past. There is no reason for putting one or the other in a priviligiated situation, so there is a kind of incompability. If you superpose the 2 POV, you will obtain multiple Marions and Pauls, which is not what is observed at no time. When you superpose the 2 POV, you obtain a diagram in which Paul is in the past of Marion AND Marion is in the past of Paul. So you get 2 Marions & Pauls: it is wrong. The diagram may give the correct numerical result for the relative coordinates of Marion & Paul, but they didn't duplicate in time. ----------------------------------- trying to explain my point: if (IF) Speed Of Light was infinite, Marion & Paul would be in their mutual present : instead of the SOL line at 45 degrees down, there would be a horizontal link between Paul & Marion. But SOL is not infinite, so there is a diagonal link between Paul & Marion. But beside the fact that the link is diagonal instead of horizontal, is that an enough good reason to postulate the existence of multiple Marions in your diagram?

Bolded mine. You are mixing 2 POV, it is like mixing 2 FOR: you can't do that and expecting to extract a safe result. If you are examining Marion, then Marion is at the origin, that is your diagram. If you want to examine what Paul's observations are, you have to make a entirely new diagram and label Paul in the place & time of Marion. You cannot superpose the 2 diagrams and declare that "we know it isn't Marion because she can't be more than one dot", it is not a safe conclusion, it is a bad mixing. Labelling is simple: each point of the diagram must be labeled with coordinates. Marion In Black is (0,0,0,0), Marion In Red is (0,0,0,-1). It is the same and one Marion at different spacetime coordinates.

Hi Cap'n that's been a while Q: why cant I see the number of a post when I am replying? In reply mode, the topics summary doesn't show the avatars (not a big concern to me) but also erases the post number, making it difficult to reference post#?? of another poster in the thread. Surprisingly, in Fast Reply mode there is no such omission.

Observation is relative. If Paul observes Marion In Red (MIR), he cannot observes Marion In Black (MIB). For him, in all his universe, Marion in Black does not exist. If he wants to measure Marion, the object Marion is Marion In Red, Mir has mass, MIR is measurable. MIR is the King on the chessboard for Paul. And for Paul, MIR is his companion. On the other hand MIB is unobservable to Paul. If MIB was a square instead of a dot, Paul would have no clue. When MIR will reach the coordinates of MIB, MIB will have gone further in time, and Paul also. The diagonal that links Paul with MIR is unescapable, Paul & MIR are tied together. Wathever is out of the diagonal is only a guess. You understood clearly in post #153

If you walk 10 meters East at 1m/s, then 10 meters West at 1m/s, you will have come back to your starting point. You will have traveled 20m in 20 seconds. Meters have added exactly the same way time has added: 20 meters, 20 seconds. At no moment you will have traveled minus meters. Change in direction does not imply that you go into negative distance. Change in direction is possible in space because there are 3 dimensions of space, it allows the rotation of distance in space. Time is alone, it cannot rotate in space. . . . Or can he?

I disagree. You must compare the single dimension of time to a single dimension of space: the line of time compared to the line of distance. Now, you may notice that a distance is always positive. Even if you turn back to where you came from, the distance that you will travel will always have a positive value. The same goes for time. There is no negative distance, there is no negative time. That's just the same.

Paul is not observable from Marion In Black, And Marion In Black is not observable from Paul. What Paul observes is Marion in red, for him, ONLY Marion in Red is observable, Marion in black is not part of his (observable) universe. If you want to discuss what Paul observes, you have to put Paul at the origin. So 1) yes Paul observes Marion in red, but neither Paul nor Marion in red are part of Marion In Black's (observable) universe. It is like saying that a planet 250 million LY away from us "today" observes dinosaurs on Earth. Neither the planet is observable to us, neither the dinosaurs. And IMHO the reason for that is that both the planet and the Earth have translated in Time. 2) He identifies Marion, the object, with mass. For him Marion in Black doesn't exist (yet). As I stated before, there is only one King in the chess game. There is only one Marion, you have to choose.

Lets do it. Put today 29th of March 2012 a mirror on Moon's surface. Is it possible to see in this mirror anything happening before 29th of March? I don't think so. The only thing that you will do is provide an instrument for the future generations in order to have a look at their own image in their past as it was 3 sec. ago. That will not prove that in the future there will be 2 Earths, one in the present and one with 3 sec. of delay.

You wrote: (bolded mine) Contradicted by this statement: If Marion is the observer, Marion is at the origin. But I will retain your statement "The triangle is her light cone so she can't see the red dot (one second behind her in the -t direction)." This only was worth the thread. That is because 2 years now I struggle maintaining that the interior part of the PLC is not observable. It was then dumped into the Forum waste basket. It is Michel's image travelling at c. @Iggy I suppose you realize that each single bar on the horizontal line represents a distance of 300000 km. Number 2 on the horizontal represents 3 million kilometers (about 7 times the Earth-Moon distance). At this scale Marion is a tiny little dot (not visible on the screen) and not a big black/red dot.

So you really believe there is another Spyman frozen corresponding for each passed instant? That you are multiplicating as time passes by? That the Spyman you see in the mirror is another Spyman?

We are indeed aboard a very heavy vehicle. How much would you need to avoid a collision? A few seconds on the orbit would be enough I think. Unless the asteroid comes face to face ,tangential to the orbit in the opposite direction (are they such asteroids?)

No. Utter nonsense. edit -too strong comment- utter nonsense IMHO, that is what we are discussing right now. Where is the strawman? I say there is not anything frozen anywhere, I simply stated that the frozen concept is the "common sense". it is like a chess game: you have only one King. If the king is in the present, it cannot be in the past. If it is in the past, it cannot be in the present. The only thing you can (theoretically) do is change the position of the King. Yes. Agree. Yes. You are understanding very well.

We could put a propulsion system on our planet to alterate earth's motion and avoid the collision.