michel123456

Not "so what?". All technological advance make less and less people having jobs. It is already a huge problem for occidental societies.

You surely mean: someone else will have to adapt. A lot of them.

Imagine 3D printing clothes. You'll do that at home from your own printer. An entire part of the existing industry will collapse. Especially if you can recycle your gel-clothe and make a new design from the old material. In the construction sector the recent technology that I am aware of is still about 2D printing. For the production of large tiles (1meterX3 meters) that are scanned images of overpriced Calacatta marble or other material.

I had multiple issues with IE on this Forum, now than a year or two I am using Mozzilla Firefox and everything is ok.

Then they will crash.

That counts when they move. the question is what happen when they meet. For the meeting they must have accelerated (decelerated) in order to be in the same FOR.

There is a repeated typo

i am a he.

To me, there is only one desk, a 3D object, that travels into time. When your desk is "here now", it is not "here in the past". It has changed spatio-temporal coordinates. I don't know where the idea that the desk extents into time comes from. In any case, the signals you get from your desk in the past also traveled into time. You cannot interfere with your desk 10 sec. ago. Even if you put a mirror 5 light-seconds away, you will not interfere with yourself 10 sec. ago. If you could do that (interfere with yourself) your image in the mirror (yourself 10 sec. ago) would be smiling at itself 10 sec. in the future, and that is not allowed by the laws of physics. The only thing you could manage to do is to see yourself as you were 10 sec. ago. Yes. But that means that you are 10 seconds before. Only one side of the mirror will be the observer. The thing in the mirror is not "you", it is a signal that you emitted 10 sec. ago. Not much different from a picture or a video tape. The "thing" on the videotape, yourself in the past, cannot observe the future observer of the tape. The same with the mirror. The observer will always observe the other "him" in the past. That does not mean that the "other him" still occupies these set of coordinates. it means the "other him" was there, emitted a signal from there, then went to some other coordinates. IOW it changed coordinates. We have nothing at hand that can prove that the "other him" occupies the entire set of past (and future) coordinates. i hope I made my point clear.

Bachet in this case, as in many others, it is not a matter of cleverness, I was wrong on that. It is a matter of memory. I mean i remembered the puzzle, ithat's all. Also many of that kind of puzzle have a trick in the first statements. Many have been made by "clever" philosophs who still laugh from their graves at the mathematicians who try (stupidly) to solve their "problem" the straight way. Ah, and I was wrong, by the "clever way of weighing" in can be done in ... One weighing

Then explain me why I observe the world around me made up of 3D objects, and not made up of 4D objects.

Maybe the problem is thousands of years old.

Sorry, i ment "entire".(i corrected my post) The definition is :what is ment by "weighing". What kind of things can you do in "one weighing". it is an old problem, I cannot recall where I have encountered it. Maybe from school. 40 years ago or so.

I have not read the spoilers. IIRC the all (entire) problem is in the definition of "weighing". The underlined part in the above. One weighing Oops, sorry, if you are very unlucky, two weighings.

Fair enough. I am glad to know that you believe that you are a 4D being. You are superior. On my side I believe that I am a 3D being.

Excuse me, I am tired, I think all you say is BS. Time is not philosophical. Time is everywhere in physics.

Where is the mechanism of time in all these representations? There must be some sort of mechanism, time exists, we feel time. Is there an explanation why we cannot observe ourselves as 4D objects? What is the reason why we can observe only our 3D section? IMHO these are all a wrong representations. I am not a 4D object from which I can feel only the 3D section. I argue that I am a 3D object that travels into a 4D continuum. In this view, the "mechanism" of time is similar to motion. In all your representations, it is so static that there is no explanation of what we observe as the phenomenon of time.

Let's take your model. Nothing changes. Thus I understand that Time acts like a scanner upon a sheet of paper. In the sheet of paper nothing changes. The past, the present, the future are static. Is that it? Then the scanner scans. It moves, it translates. No?

So you say that in the twin paradox, when the twins meet, they are not meeting simultaneitly? The one is in the future of the other? I don't think so. Simply they have aged differently. When they meet, they meet. That's what a meeting is.

Yes you need time, time is there, point. Similarly, you don't need extra space to have space.

Correct me: Your understanding is that, while living in a 4D world, we are 4D objects. My understanding is that we are 3D objects traveling in a 4D world.

I don't disagree with the bold part. I haven't said that "particles travel through time at the same speed. A second per second.". I said particles change coordinates. It baffles me that we disagree on what motion is. Motion, classically, is a change of spatial coordinates. Velocity is a change of spatial coordinates in relation to time coordinates. The concept that says that particles extend through the time dimension like spaghettis is outside the concept of motion. IMHO. The Krikalev argument is unaccurate, he hasn't travel in time the way you say he has. He has been time dilated.

I don't think GR says that. Otherwise Einstein couldn't question the existence of time itself. it is an interpretation. Of philosophical nature according to Swansont

That is strange. Light cones are diagrams that come from Relativity. I may be misinterpretating something. I begin with 4D spacetime continuum. that is relativistic stuff. I begin with SOL as a constant. that is also relativistic stuff. Then i say that we cannot observe directly the inside part of the light-cone. if you don't like that, I can drop it. Anyway you will agree that the outside part of the light cone is not directly observable. that is not contradicting relativity as far as i know. Then i say that particles change coordinates in 4D continuum. You and many other disagree. Anyway i do not see where my position contradicts Relativity. Where am I so wrong?