michel123456

bolded mine: that should ring a bell.

O.K. as it seems you have a problem with time. You prefer motion. Do you have the same kind of problem with space?

If you can see your hand move through space, it means you can "see" time. Otherwise your hand would be "frozen in time" so to say: existing only in space (can that be?) here below a good reading, IMHO. http://web.mit.edu/bskow/www/research/temporality.pdf

Daniel, you can use the same kind of argument to say that distance don't exist. But we know that distance represents "something" that we capture from the physical world by measuring it. The same goes for time: "something' is happening and we are measuring it. I think it is not reasonable to argue that we can measure something that does not exist.

If time doesn't exist, what is that t we encounter in so many equations?

Fixed. I had to toggle again in normal mode, pick at the end of the quote (outside there was no place to tick) and hit the Enter button several times to go out (as String said). I thought having done this but obviously not. In simple mode it was clearly impossible. Even the preview changed automatically the place of the . edit: now I remember having hit the Enter button many times, then the window expands After several hits, i was able to click outside.

Very weird. It's OK in this thread, but it's not in the other thread.

Yes. i also tried using the toggle button but even in simple mode, after moving the Quote , the post appeared wrong. I even cut my answer, post the reply without answer, then edit again and paste my answer after the quote sign, again wrong. Very weird. ------- Note, from this other machine, no problem.

guys i don't know what is happening, i have serious issues. working from another machine (.still IE8). the edit function of a post does not understand that I want to answer after the Quote. I do it again & again, it does not work. Look below. It's getting really worriyng... http://www.scienceforums.net/topic/71281-universe-expansion/?p=718716 yesterday, from another machine (out of a number of 5), i was unable to see the whole "my profile" pulldown menu. Only the upper part with half my avatar.

I'd prefer a better theory right now. i don't have the patience to wait for a billion years. ------------------- .............. (bolded mine) I am not sure if I understand correctly your question, but it's an interesting one. in my understanding mass is used only once over time (mass does not multiply along the word line of a massive object) and i guess the same must happen for energy.AAARGH i am getting crazy, no way to put my answer outside the Quote... ------------- (edited -done)

we agree so far. The situation is not symmetric. An alien on that very distant galaxy looking in our direction will observe something that is 46 billion years in his past. He cannot observe us that are 46 billion years in his future. If you go out and wave your hand to the stars, only aliens that are in our future will be able to see you sometimes, eventually.

grmblmmm. I need help. I use now Godzilla Firefox. The monster sends me automatically to spam sites with almost any click, for example opens a new tab with some stupid add when I want to hilight some text in a reply. What have i done for this?

(bolded mine) Reversely, doesn't that mean that we are receding from those oldest remnants at speed greater than 56 times the Speed Of Light?

IIRC that is the standard POV. The metric of space is expanding.

(bolded mine) The "increasing rate" will become obvious only when the time axes are showned. That's why I asked about the position of time axis for T=2.

Yes I was looking for the "cancel" too. It would be great if it was next to the "Post" button instead of opening the "More Reply Options". Also the "report" button is terribly close to the "Edit". I'd prefer the "report" somewhere on the left, alone.

If I have to suppose that a single sound has multiple frequencies, then for a moving source the answer is yes. But if one has to compare to what we are observing in the sky, one has to consider 2 objects at 2 different distances from the observer, going away at the same velocity compared to the observer and emitting a same sound of the same frequency. In this case If I understand correctly the 2 sounds will have the same frequency shift (as heard by the observer), because the doppler effect is a function of velocity and not a function of distance. --------- edit So in the sky the doppler effect is caused by a difference in velocity. Please correct me if I am wrong.

Yes. Today I see everything too. I am illiterate that's why I understand nothing... Still; having the issue with the grey screen and nothing happening when pushing the "image" button. All other buttons are working fine. Anyway I switched to Firefox.

Ill have to dig to find an old thread where I went to argue that the reverse movie is not a good representation of time reversal. The argument is that all 4 fundamental interactions must be reversed, not only motion. One should imagine reverse matter under reverse energy acting reversely.

There must be something wrong here. Can a second great circle be perpendicular to both geodesics ?

So you say that along the T axis there is a physical interpretation (that objects get closer to each other at an accelerating rate) but that along the X axis there is no physical interpretation. I disagree on that. IMHO the interpretation is that objects far away happen to coincide in time (they are at the intersection of time axis. It also means the time rate diminishes the same way distance diminishes. i agree that a sphere is not a realistic spacetime but it shows that when something "weird" happens in space (like 2 parallel lines intersecting), a similar "weird" phenomenon must happen in time.

What is the physical meaning of this?

So all x axis intersect.

Great explanation! How do you draw the situation at T2 in your spherical diagram? (where is the horizontal axis at T=2 ? }