michel123456

Incidentally, I tried to compare the 2 graphs (marriages versus divorces)and noticed they just can't be juxtaposed. The scale along the vertical is different from one graph to the other, and I hate that (sorry for the Australian Bureau of Statistics). So I made a quick transformation and obtained this one: I suppose you cannot compare marriages and divorces on the same year because it takes some time (usually) before divorcing. So the correspondance between the 2 graphs should be seen along some diagonal, according to the average marriage duration before divorce.

There was a precedent with Albert Eschenmoser's TNA Quoted from this article in nature.com found this about TNA http://www.rsc.org/chemistryworld/News/2012/January/RNA-world-hypothesis-TNA-primordial-soup.asp There are probably earlier findings I am not aware of. Fascinating.

I guess the man did what I would do:

Thank you.

Time is a scalar, not a vector. Time as a vector is speculation (interesting though). Distance is also a scalar. Physically, since nothing can go faster than SOL, the delayed observation of the object "is" the object, meaning that in our equations the only thing that physically matters is the delayed observation. The "real" position of the object, wathever that means, is out of physical interactions. The question I am debating for so long with Iggy is the following: _do you believe the object is static in spacetime, "existing" all the way long, represented in a spacetime diagram by its world line? or _do you believe that the object changed coordinates in spacetime?

My conclusion is that time and space have different properties. Well, if I saw an apple changing into orange under a simple rotation, I'd say there is something wrong somewhere. Physics don't behave like a magician, physics don't change apples into oranges just like that. What could possibly happen is that what I observe as an apple is in fact an orange, or vice-versa, or even that what I observe is a very peculiar fruit. As an analogy, think of a tetrahedron. A tetrahedron has 4 faces. But if you look at at it, you can observe only 3 faces. Call the visible faces "Space"(or Apple) and the hidden face "Time" (or Orange). If you rotate the tetrahedron, there will always be a hidden face. And what you observe as Space may be observed as Time by another observer. The tetrahedron is a single entity, it is not something that 'transforms" into something else. The "transformation" is caused by the difference in position between the observers. The "transformation" is not a magic trick, it is an observational consequence. IMHO spacetime is a continuumm of 4 dimensions that must share the same properties, like the 4 faces of the tetrahedron. No face is different from the other, only one is always hidden. If the properties of Time were so dramatically different from Space, no observer in no FOR would call time what I call space. Of course there is a difference between Space & Time. Space is 3D and Time is 1D. In the terahedron analogy, the 3 visible faces are called "Space" against the only one single hidden face called "time". So, the properties of 1D Time are not to be compared to 3D Space, but to the 1D equivalent of Space, called Distance. And if you put "common sense" aside, and compare Time to Distance, you will maybe see that there are similarities. And from all similarities, the most outstanding is that distance can be measured with a clock.

You understood very well. I'll take your answer for a yes. That corresponds to point 6. of the OP So if you can rotate apples and after rotation they become oranges, what would be your scientific conclusion?

This part must be wrong. I am really sorry. The vertical vector also induces horizontal motion to the piston. Only proper calculation can tell.

I made this on the original OP sketch: point A is the Bottom Dead Centre (BDC), point B is the Top Dead Centre (TDC) Both at points A & B the speed of the piston is null. The distance traveled by the piston is equal to the diameter of the circle 2R= 2 times the distance HG. So without calculating anything I suspect that the top speed of the piston will be when the crank will be exactly in between i.e. at 90 degrees (point F) and not when the angle HPG will be 90 degrees. IOW the horizontal speed of the piston corresponds to the horizontal speed of point H at any time. and since as Imatfaal wrote "The point H has its highest horizontal velocity at 90 degrees", so does the piston.

Is time rotatable in space?

That's the 2nd time in this thread that we agree on something, champagne! Just because they have another sign? As much as I know +1 and -1 are different but not so dramatically that they cannot work together. Like time & space, you can make operations on positive & negative values of objects that have equivalent properties like the integers. The fact that time coordinates have a different sign from the spatial ones does not mean that they don't have the same properties. It simply means that they have another orientation, perpendicular to space. (please correct me if I am wrong) IMHO if time is rotatable in space, time & space must share the same properties.

Except that if the piston was at the dead centre position, the speed would be null, and the angular speed also null. But the sketch disagrees. As it is drawn, the piston is not at the dead position. So, after reading all this twice, I still don't understand the statement. I had in mind a stupid mechanism like this: Because it is nowhere said that the piston is aligned with the center G (although it may seem evident).

Oh yes, you must be right. So the angular velocity of HP is also asked for this particular instant I presume.

So what? I don't understand the statement. In the graph the 60 degree angle is with the PG axis. In this position, P is not the "dead centre" position. Or am I missing something?

That is untrue. Is that untrue? or will you tell me that the (...) is important.

What is this information used for?

Sorry taking back my post.

You are confusing right/wrong with legal/illegal (or commonly accepted/unaccepted) Laws may vary from place to place and from time to time. In time of war you may be obliged to kill, it will not be considered murder, under certain conditions. But you must always be able to recognize right from wrong.

You got it. You are treating the 4th coordinate differently from the 3 others. That is my question: why? If time can be observed as space by some other observer in some other FOR, the t coordinate should be treated equally to the 3 others. x=y is a mathematical description. It can be a lot of things, a trajectory for example.

If you are under trial and you cannot recognize what is right from what is wrong, you will be considered irresponsible and conducted to the asylum. But maybe I am wrong on this.

That makes sense. But the question is not about the amount. The question is about the properties of the process. I had this bad feeling today that we disagree on what motion actually is. When I have a pencil on my desk, then change its place upon the bookshelf on the right, the pencil moved. In my world view, the pencil changed coordinates in spacetime: At t=zero it was at coord (0,0,0,0) with spacetime coords (x,y,z,t) At t=1 it is at coord (1,1,1,1) no matter the units for the sake of simplicity. If I understand correctly, your interpretation of reality is fundamentally different. For you, the pencil that was at coord (0,0,0,0) occupies this coordinate once for all. It will never leave this coordinate empty, no other object can occupy this coordinate. For you, when the pencil moves from (0,0,0,0) to (1,1,1,1), in fact it stretches from one coordinate to the other in the time dimension. In this view, the change of coordinates of the last number has a totally different meaning than the change of coordinates of the first 3 numbers. And I wonder if there is any good scientific reason for that.

Bolded mine. If motion through space is different from motion through time, how is it possible for time & space to be interchangeable according to the observer's FOR ?

The black dots represent different things, that's why. That should be your stronger argument. I agree it is weird, but I had no other way at disposal to put in front of your eyes the concept of an object changing coordinates versus your concept of an object extending from one coordinate to another.* As I stated before: There is no reason why translation in space (motion) should be so radically different from translation in time (duration). when you move in space, you change coordinates, you don't 'persist" from one point in space to another. The same must be true for time: as duration occurs, you change coordinates, you don't "persist". * What I can assure you is that it is not necessary to extend from one coordinate to another, all can be explained with a change of coordinates.

Bolded mine. Yes, I thought it was evidence. But some other people told me it is not at all comparable to motion, that objects "persist" in time, with backup the whole scientific community as it seems. I really 'd like to know why on one hand it is commonly accepted as a language figure that we are continuously "traveling in time" from the past to the future, and on the other hand when it comes to put this "travel" into diagrams one encounters such a resistance.