michel123456

Sorry if you feel that way. I know that the common understanding is the Block Universe. The B.U. is a frozen thing in which nothing happens. There is no "motion in time" in the B.U. There is this "window" that slides all along. But then there is the concept of motion: changing coordinates in space. If time has also the effect of changing coordinates in a 4th dimension, then one should accept that there is change in time. (anyway the window sliding is a kind of change, isn't it?) That means that time (maybe) allows change. It is a very different picture from that of the B.U. where the introduction of time forbids change (everything is frozen). Once the concept of change of time coordinates cross your mind, the consequences are inevitable (and I am surprised nobody else so far has taken the risk to evaluate this consequences).

No. Where are the photographs? Are they in the past? or are they in your hands? Are the photographs the same thing as the event? Or are they a record?

That is the wrong question. Think better. Yes.

I am asking everybody here to digest what Eise wrote here above. And to get firmly in mind what motion is. It is a displacement in space and in time. A displacement. And not a copy. If you digest the displacement, well, drive your conclusions by yourself. You may get a glimpse of the universe.

You realize that it is not what Eise was describing, do you? you are describing what is presented in the video, where what is moving is this "now", the slot as I call it. At least you admit that "something' is moving in time, I hope you realize that. You don't have solely a Block Universe, you have "something" (the slot, the "window of causality") that moves. It means that you are accepting some kind of change in time, and not only a frozen 4D entity in which nothing happens. Well, because everything is relative, instead of a slot that is scanning a frozen 4D Block Universe, try to imagine a slot that is still & objects that slide in time. Doesn't that give the same apparent result?

And sometimes I read what I want to read instead of reading what is written. Of course. If you agree that they are gone, doesn't that mean that their spacetime coordinates are vacant? How else would you translate the "they are gone".?

🙂 Sure. Educated disagreement is fine. Yes, it follows an uninterrupted path through spacetime. The word "persist" is disturbing me. It looks like you are accepting that objects "move" into time along a path & also accept that the object persits in time. I am afraid you have to choose the one or the other, these are incompatible statements. Yes, the path is history carved into stone. You cannot change it. I do not disagree on that. But it remains a path. Julius Caesar & Napoleon are dead, they are not "persisting" in time, in another dimension. They are gone. Oh sorry, maybe are you using the word "persist" to say that the object does not vanish in present time? I had the wrong understanding that you believe that objects are persisting in the past. I am confused.

If you can't access the coordinates then you cannot change what happened then. We agree. But that doesn't mean that there is something there, or that there isn't. We simply don't know. We are assuming (guessing). Quoting myself: am I wrong saying that? Note: in the quote you can replace the word "if" with the word"when" and it becomes: My understanding is that the points that form this line are mutually exclusive. When I am at t=100, I am not anywhere else. When I am at t=2, I am not at t=3. The physical entity is only one point of the line. The whole line is a path.

Oh, what a disappointment. I thought we were on the same stance when you posted: Now you seem to support the idea that objects are 4D entities when you say that they persist in time. You said:

My understanding is that the points that form this line are mutually exclusive. If I am at t=100, I am not anywhere else. If I am at t=2, I am not at t=3. The physical entity is only one point of the line. The whole line is a path.

If "flying" in time is so much different from "moving" in space, how can we compute mathematical theories where the one rotates to become the other? Is it possible that "flying" in time corresponds to Copy? When we all know that a move in space is a ... move.

See, that is the difference between you and me (and Eise). You are supporting the concept that objects are 4D. That I am extending in time from my birth till my death. Eise said that no, spacetime is full of events, not objects. You are saying that spacetime is full of objects. You are disagreeing with the concept of 3D entities "flying" in time. You prefer the concept where entities are "extruded" in time.

My point is: since we all agree (do we?) that we "fly" in time, each one of us occupies only one single spacetime coordinate, objects are not 4D extending back & forward in time. If you are in the present, you are not in the past (anymore) and you are not in the future (yet) As a consequence, if we are using only one set of coordinates, then the other sets are free.

And not to say that the signal of the event is spreading at c all around, leaving the coordinate completely empty. What all observers will agree with is the signal that they will receive from the event.

I am not there anymore. There is no object at this spacetime coordinate. There is only an event: Michel was there.

No. As far as i see it, even in my interpretation, there is no physical way to change our own past. It is not observable and not reachable. But the question is still there: If we are "flying" along the time dimension, if the spacetime diagram describes what I call a path, what Eise calls "process", then does that mean that our past coordinates are empty? And that all our future coordinates are empty also? Or are they full, as presented by the Block Universe concept. From what I understand from Eise's post, the past & the future are full of events. Objects belong solely to the present. Am I correct in this or am I putting words in his mouth?

I firmly believe that the concept of time is more close to that of space than is commonly assumed. There is no reason it would be fundamentally different otherwise how would it be possible for time to change into distance & reversely. This is history, for the 1st time I agree 100% with someone here. So, if we are "flying" through time, doesn't that mean that our past coordinates are free? And our future are free also?

It makes sense exactly as the footsteps in the snow. There can be a dog following me and his steps cross mines. However this crossing will not have changed my past. After reading your comment twice, maybe do you agree with the "path" concept. Well I assumed that conventional thinking is that the objects are 4D entities, represented with segments on the diagram. By "process", what do you mean? As if you agreed that objects are "moving" in time.

We do have an extent in time as objects. Because we have dimensions in xyz we also have a dimension in t, but it is limited to an extremely small figure because c is very large. For example my hand at ~50cm of my eyes is slightly back in time (the same way that we are observing planets back in time). But this extent in time does not cover my entire existence. If it did, for an extemely small time-lag, there would be an overlap of 2 Michel123456's. If you take an object large enough, like the Earth, diameter 12740 km, after a 0,04 sec (if my calculation is correct) there would be an overlap with the "Earth-extended-behind-in-time". We do not observe such a thing. Anyway, since we have already an extent in time as objects we cannot have a 2nd kind of extent in time.

I even understand the counter argument of what I am saying. The counter argument is that I have introduced change in the 4D universe which means that I have introduced time in time. But that is also the way the video is presented. The slot moves upward in the 4D continuum. And that have annoyed nobody here.

I understand. But, to me, we don't "also occupy future positions", and we don't "extend in the time dimension along a world line". We cannot both be in the past, the present & the future, these are mutually exclusive situations. If you choose a position at a past coordinate, you are there and nowhere else. if you choose a position in present time, you are not in the past. And you are not in the future. To me, 3D objects are not 4D entities reduced by 1 dimension. 3D objects are what they are: 3D. Simply they travel through a dimension we call time. In this concept, Time is simply an extra dimension, Time does nothing, Time is a kind of empty receptacle exactly as Space is. Time doesn't "pass by". Objects change position in Time. When I say that they "change position", I mean exactly as objects change position in space. They do not copy themselves from one position to the other. Yes we remember it, we have a photograph of the event, we even have it recorded and carved into stone. But does that mean that the event is frozen forever at some coordinate in time? A coordinate we have currently no access to? Just because it is physically impossible to change our past doesn't mean that we are stuck there. Yes the path exists, the picture of the event is here in present time, I can look at it, and the marble stone is also here in present time. And if the stone is here now then it is physically impossible to be in the past or the future. There are no 3 stones. There is only one, and it is in the present. If a new event happens in our past (although seemingly impossible under current understanding), this "new-old" event will not make any change to the picture nor to the stone. Because the picture & the stone are not there (anymore). They have traveled together with us in present time.

The video

The simultaneity of events as observed by the observer. I see today a star exploding. This star may have exploded a long time ago but I see it now. The slot is this now.

The slot yes. But not the image when you remove the sheet & show the B.U. Not to say that the comment at the end of the video shows the embarrassing situation that occurs with the B.U. concept: the future is already there, and in order to avoid the "already existing future" one has to invoke quantum fluctuations (as an ex machina explanation). let me explain once again: IF (if) you can accept that objects travel through time (that objects change time coordinates), you may also see that the slot in the sheet is unnecessary. My point is that simply objects move in time exactly as they move in space. they change position, they do not copy themselves. They progress from down to up. Objects are not "extruded" through time. Objects are not 4D. Objects are 3D entities that travel in a 4D continuum. Sure you can show the path of this object in 4D, but it will be a path, not a 4D object. The same as your footpath in the snow. At each instant you are somewhere at a specific point of the path, you are not extended all along your footsteps.

Right. It is not. If you get the concept of the vanishing path, you may also get the concept of the empty future. The situation resumes to an empty universe behind us & an empty universe in front of us. The unique things that exist are the ones that travel with us in time enhanced by the slot in the video. Maybe yes. Maybe no. I am often surprised with the many possible interpretations of this Theory. From the video, if you agree with it, you may observe the slot that moves upward. It represents the simultaneity between events. In cosmology, the slot is not horizontal, it is inclined (at 45 degrees) in such a way to show that the observer gets information from the past. But fundamentally that changes nothing, the only events that currently happen belong to the slot. If we send a spaceship to Alpha Centauri (that we observe as it was some time ago) we will see it all along its path during the travel & we will eventually see it land (or orbit) Alpha Centauri, constantly inside the slot. At no time the traveler will escape the slot. The entire observable universe is upon this slot. The rest is supposedly full if you believe in the Block Universe, or empty following the "vanishing past" concept.