I see you, You see me.

[dimreepr]

2 minutes ago, michel123456 said:

"Then say that the horizontal segment from A to B is the entire Observable Universe." the important word is IS. To me there is a split between what information we get (the image) and what is.

And that's been your block, but undoubtedly not in the way you imagined; and we're back to "you can't cross the same river twice whilst I cross the same river everyday".

What is, wasn't? 

[MigL]

On ‎3‎/‎9‎/‎2020 at 10:34 AM, michel123456 said:

If I can observe a far away Galaxy, then theoretically an alien on this Galaxy can also observe me(1). Like Alex & Beatrix. The alien is not in the past, he has traveled in time as we did.

No he has not.
Any information regarding the alien has travelled the separation.
That information is current to the past time; it does not get altered along the way.

Any space-time diagram applies only to YOU, the observer at the origin.
Anybody else's will be different.
You cannot put two 'observers' in a space-time diagram, and try to make observations fit both sensibly.

[michel123456]

OK my message does not go forward.

Back to the basics: Motion

I have momentarily edited some of my graphs to depict motion in Space. Time has been erased & replaced by space.

Here a ball (labeled A) sliding on a desk

graph 14

No more Time on the graph, no more spacetime diagram, only a ball sliding in space. The ball changes coordinates as time passes by.

And here below graph 15, I hope we can all agree that it is NOT an accurate depiction of motion:

Graph 15 utterly wrong. The ball does not multiply when changing coordinates.

The "multiplication" is a property that we attribute to Time: the ball is supposed to persist in Time. While Space has no such a property.

Any comment so far?

 

 

Edited March 10, 2020 by michel123456

[Eise]

15 minutes ago, michel123456 said:

It is a map. A spacetime diagram is a map. A way for us to depict reality. Can we agree on this?

Yes. But on this map should be visible that A was at X₀ at T₀. No exception, otherwise the map is a false depiction of what really happened.

On 3/8/2020 at 9:31 PM, michel123456 said:

If you make the comparison between graph 3 (accepted) & graph 5 (speculation), which one is simpler?

So the right graph is definitely wrong. When A was at X₀ at T₀, then this should be shown. This fact does not change, never changes.

The left graph is just confusing: on one side you show a spacetime map, being a depiction in space of a timely 'process', e.g. of A keeping seated in his chair, and then you add another time dimension by animating the graph. But in reality we only have one time dimension.

So this the the only correct way to depict 'A was sitting in his chair at X₀ from T₀ to T₄'.

 

[dimreepr]

1 minute ago, michel123456 said:

No more Time on the graph, no more spacetime diagram, only a ball sliding in space. The ball changes coordinates as time passes by.

Ok, now you owe me a new meter... 🙄

[Eise]

9 minutes ago, michel123456 said:

Graph 15 utterly wrong. The ball does not multiply when changing coordinates.

Right. That is because now you have made a 'spacemap', and the only time dimension is in the animation. 

10 minutes ago, michel123456 said:

The "multiplication" is a property that we attribute to Time: the ball is supposed to persist in Time. While Space has no such a property.

But time also does not 'multiplicate': in a spacetime diagram you depict events: objects, that persevere through time, must therefore be depicted as a chain of events: A sitting at X₀ at T₀, A sitting at X0 at T_1, A sitting at X0 at T2, etc. That is a process, or a series of events.

 

[swansont]

1 hour ago, michel123456 said:

 It is a map. A spacetime diagram is a map. A way for us to depict reality. Can we agree on this?

Consider a map with only spatial coordinates, like a real map. You generate a new map for each value of time.

Paris is on the map in 1800. That doesn't change just because it's 2020. 

You can animate those maps and see how the maps change over time. But all of the maps will have something in them. The ones depicting history don't go blank. 

 

[michel123456]

23 minutes ago, Eise said:

 

Quote

But time also does not 'multiplicate

I am happy to read that.

Quote

in a spacetime diagram you depict events: objects, that persevere through time, must therefore be depicted as a chain of events

Well understood.

Quote

A sitting at X₀ at T₀, A sitting at X0 at T_1, A sitting at X0 at T2, etc.

If you pick one from the set , say "A sitting at X0 at T_0",  don't you have an object at hand?

9 minutes ago, michel123456 said:

chain of events

This chain of events I call a path. In utterly wrong graph 15, the bold line is a path.

There is only a single 3D object sliding in Space. My speculation is that in Time the same exactly happens: you have a 3D object sliding in Time.

And i really don't understand why it is so difficult to accept.

Edited March 10, 2020 by michel123456

[dimreepr]

25 minutes ago, michel123456 said:

And i really don't understand why it is so difficult to accept.

Isn't that your problem???

[Ghideon]

 

 

1 hour ago, michel123456 said:

No more Time on the graph

Ok!

38 minutes ago, michel123456 said:

In utterly wrong graph 15, the bold line is a path.

My opinion* is that if time is removed then the bold line and graph 15 is correct, or as correct as a single frame from graph 14 would be. In other words, there is either one frozen moment (a frame from 14) or everything happening at "the same time" which would require the ball to be everywhere along the path (bold line in graph 15).

 

While writing the above I think I see your point of view regarding "3D object sliding in Time".  But I have to think some more before commenting further, not sure yet how to formulate something that makes sense. 

 

*) Disclaimer: Not sure this is rigorous enough to have any value in a science discussion

 

[michel123456]

28 minutes ago, Ghideon said:

 

 

Ok!

My opinion* is that if time is removed then the bold line and graph 15 is correct, or as correct as a single frame from graph 14 would be. In other words, there is either one frozen moment (a frame from 14) or everything happening at "the same time" which would require the ball to be everywhere along the path (bold line in graph 15).

 

While writing the above I think I see your point of view regarding "3D object sliding in Time".  But I have to think some more before commenting further, not sure yet how to formulate something that makes sense. 

 

*) Disclaimer: Not sure this is rigorous enough to have any value in a science discussion

 

Maybe to help you understand my way of thinking: I am speculating that we are not 4D entities, but 3D entities sliding in time. The "room in time" we call "the future" is empty (we are not there yet) and in an astonighing way the "room behind us" we call "the past", is also empty (we are not there any more).

Edited March 10, 2020 by michel123456

[dimreepr]

What's really astonishing, is that you still don't understand, or want too...

[swansont]

2 hours ago, michel123456 said:

There is only a single 3D object sliding in Space. My speculation is that in Time the same exactly happens: you have a 3D object sliding in Time.

And i really don't understand why it is so difficult to accept.

Is that really the sticking point? Is there anyone that objects to the concept of an object moving through time?

[michel123456]

1 hour ago, swansont said:

Is that really the sticking point? Is there anyone that objects to the concept of an object moving through time?

!! But when I propose that ancient & future spacetime coordinates are empty you are disagreeing. How else do you understand the word "move"?

Edited March 10, 2020 by michel123456

[Mordred]

Time will never be a thing. No matter how much you try To make it so.

It will always be a rate of change.

[Eise]

16 hours ago, michel123456 said:

If you pick one from the set , say "A sitting at X0 at T_0",  don't you have an object at hand?

I do not quite understand your question. Or it is obvious: the phrase "A was sitting at X₀ at T₀" means "The object called 'A' was sitting at X₀ at T₀". So there was an object at hand.

15 hours ago, michel123456 said:

I am speculating that we are not 4D entities, but 3D entities sliding in time. The "room in time" we call "the future" is empty (we are not there yet) and in an astonighing way the "room behind us" we call "the past", is also empty (we are not there any more).

No. The space (X₀) where A was at T₀ is (possibly) empty now. But it definitely was not at T₀.

The problem you seem to have is that on one side you are right that spacetime is a kind of unity, but but on the other side you do not see that time is not the same as a space dimension. By transforming time into a distance in a diagram, you lose this 'specialty' of time: what is special about time you must have always in the back of your head, when drawing events and/or processes in a spacetime diagram. E.g. when you draw a worldline that implies that an object is travelling faster than light, then you made an error. However nothing in the drawing tools of a spacetime diagram (pencil and paper, or gif-generator) can forbid this: you can draw what you want, even if it does not make any physical sense. Another example: drawing a line that implies travelling backwards in time. Easy to do, but physically meaningless (unless your are doing QFT, but I think we can forget that here).

• If you make a space-diagram of the chair now, it is empty.
• If you make a space-diagram of the chair at T₀, A was sitting in the chair.
• If you make a spacetime-diagram of the chair, it must encompass both now and T₀, which means you must show that A was sitting there at T₀.

Latter point simply means that you must mark the chair as 'occupied' at T₀. A was sitting there, and he not sitting there now has nothing to do with it.

[swansont]

14 hours ago, michel123456 said:

!! But when I propose that ancient & future spacetime coordinates are empty you are disagreeing. How else do you understand the word "move"?

You've never adequately explained why you mean by "the coordinates are empty" despite requests.  

I don't have a problem with (viewing this with classical physics) "a point particle occupies one unique set of coordinates" which would mean only one time coordinate for one's current location in spacetime. But spacetime coordinates can be used to record events, too, so your statement that "the coordinates are empty" carries with it more implications than occupying a unique set of coordinates. Because I can refer to some set of coordinates with t prior to my current time, and if something was there at that time, I don't see how you can say that coordinate is empty. Paris existed in 1800. Saying that coordinate is empty is, to me, saying that Paris did not exist in 1800.

History is not time travel. You seem to be treating them as the same thing.

 

[michel123456]

3 hours ago, swansont said:

I don't have a problem with (viewing this with classical physics) "a point particle occupies one unique set of coordinates" which would mean only one time coordinate for one's current location in spacetime

Yes. You said it much better than me.

Since it "occupies one unique set of coordinates" (only one time coordinate for one's current location in spacetime), it means at this specific time & location, there is no particle at the previous time coordinate & location, and there is no particle in the forward time coordinate & location. The other way out is to conclude that in the previous & forward locations we have the same particle and in this case this is not "motion" in time.

And further, because it is bizarre to have a vacant coordinate (is it possible to have a void in the 4D universe behind and in front of us??), the answer is that  there is another (hypothetical) particle in previous time coordinate & location, and there is another (hypothetical) particle in the forward time coordinate & location.

16 hours ago, Mordred said:

Time will never be a thing. No matter how much you try To make it so.

It will always be a rate of change.

That's another point of view. Consisting in saying for example that time is degree of freedom in Space. In this case, Time is not properly a dimension, like Space is. And  then I am completely wrong. But is it compatible with GR?

3 hours ago, swansont said:

But spacetime coordinates can be used to record events, too,

Yes.

 

3 hours ago, swansont said:

so your statement that "the coordinates are empty" carries with it more implications than occupying a unique set of coordinates. Because I can refer to some set of coordinates with t prior to my current time, and if something was there at that time, I don't see how you can say that coordinate is empty. Paris existed in 1800. Saying that coordinate is empty is, to me, saying that Paris did not exist in 1800.

History is not time travel. You seem to be treating them as the same thing.

I agree that Paris existed in 1800, I am not discussing this. What i mean is that Paris in 1800 is not directly observable, and paris in the year 3000 is not directly observable. What says that paris existed is our record of it. My speculation states that all observers from our observable Universe will theoretically agree on that (because we are linked by the symmetry I See You/You See Me). But an hypothetical observer from an hypothetical universe behind us or forward, will observe & record something different.

Edited March 11, 2020 by michel123456

[Eise]

7 minutes ago, michel123456 said:

Since it "occupies one unique set of coordinates" (only one time coordinate for one's current location in spacetime), it means at this specific time & location, there is no particle at the previous time coordinate & location, and there is no particle in the forward time coordinate & location.

My toes curl in their shoes... This is so utterly confused!

Just read carefully, I cite, and emphasise:

it occupies one unique set of coordinates" (only one time coordinate for one's current location in spacetime)

But at a previous location it was another time coordinate, so another unique set of coordinates.

Both are points on the world line on the spacetime map.

Slowly I have the feeling I am debating the colour of a rose with somebody who is red/green colour blind, but denying that that is the case, and says that the flower and the rest of the plant have the same colour.

 

[michel123456]

Just like crossing paths: just because I let this path in the snow does not mean nobody else can cross my path. It is just a path.

7 minutes ago, Eise said:

My toes curl in their shoes... This is so utterly confused!

Just read carefully, I cite, and emphasise:

it occupies one unique set of coordinates" (only one time coordinate for one's current location in spacetime)

But at a previous location it was another time coordinate, so another unique set of coordinates.

Both are points on the world line on the spacetime map.

Slowly I have the feeling I am debating the colour of a rose with somebody who is red/green colour blind, but denying that that is the case, and says that the flower and the rest of the plant have the same colour.

 

One (enhanced by me). Not two, not three.

If you say that you can occupy multiple coordinates in time at the same location, then you are not talking of "moving" in time. You are "persisting" in time.

In this last case, you are not "changing time coordinates". You are continuously extending from the one behind to the next in front, you are "building the Block Universe".

 

And I disagree with this last concept.

19 hours ago, swansont said:

Is there anyone that objects to the concept of an object moving through time?

It seems yes.

Edited March 11, 2020 by michel123456

[Eise]

1 hour ago, michel123456 said:

One (enhanced by me). Not two, not three.

You forgot my 2^nd sentence:

1 hour ago, Eise said:

1. it occupies one unique set of coordinates" (only one time coordinate for one's current location in spacetime)
2. But at a previous location it was another time coordinate, so another unique set of coordinates.

1 hour ago, michel123456 said:

If you say that you can occupy multiple coordinates in time at the same location, then you are not talking of "moving" in time. You are "persisting" in time.

If you have the same location through time, then you only move in time, which means persisting in time in this case. When you change location, you are not only moving in time, but also in space. And you still persist in time. So 'persisting' has nothing to do with it. That is what objects always do, until the moment of destruction: persisting. I recognise my car when it stands still, and I still recognise it as my car when my wife drives with it. 'Persistence' is simply the way of being of certain kinds of metaphysical entities, identifiable as the same object through all kind of processes. So they can play a role in different events. And events do not persist: they only exist at an exact time and place.

1 hour ago, michel123456 said:

In this last case, you are not "changing time coordinates". You are continuously extending from the one behind to the next in front, you are "building the Block Universe".

No, that does not make a Block Universe yet. It is just a spacetime map. You cannot draw any (meta)physical conclusions from it.

[michel123456]

8 minutes ago, Eise said:

If you have the same location through time, then you only move in time, which means persisting in time in this case

Obviously we have in mind different concepts of persisting.

We are not applying the same definition.

_If i understand clearly, for you "persisting" is the fact that you recognize the same object as time passes by. I do not discuss this.

_To me "persisting" is the continuous occupation of past time coordinates as time passes by. I miss another wording for this. It is incompatible with "moving".

Edited March 11, 2020 by michel123456

[Mordred]

1 hour ago, michel123456 said:

 

That's another point of view. Consisting in saying for example that time is degree of freedom in Space. In this case, Time is not properly a dimension, like Space is. And  then I am completely wrong. But is it compatible with GR?

Any other point of view would not be consistent with any physics model including GR.

Though it is a dimension as any independent variable ( degree of freedom) is precisely what a dimension is defined as.

Space has three independent variables. Time makes the fourth independent variable.

[dimreepr]

1 hour ago, michel123456 said:

Just like crossing paths: just because I let this path in the snow does not mean nobody else can cross my path. It is just a path.

You're essentially agreeing with my river analog, from two pages ago...

[MigL]

I refuse to go any further down the rabbit hole...