michel123456

Left & up, next to the "font" window, there is also the interesting "special BBCode" button with funny effects Like this "Speech Bubble" Like this "Speech Bubble"

Question: when the radars & other acars & gps system are turned off, does the pilot know where he is? How does he know his position and what direction is he heading to?

Derailing a bit: is the bold part above a correct statement? A body at the centre of the Earth would feel no acceleration from gravity?

Nihil novi sub sole. Reading the Wiki article about the Crimean war (October 1853 – February 1856: Some excerpts chosen not at random And the most sarcastic quote IMHO Casualties? 220,000 for Russia 300,000-375,000 for the Ottomans, French, British, Sardinians. Almost 600.000 dead before "peace became possible" Isn't that pure madness?

Call me a naive, but I will never understand why nations do not behave like individuals. For example, say that your neighbour has a beautiful room with a spendid view on the lake and a bacony just over the calm waters. He let's you come there for fishing, the whole year long. At some time, your neighbour divorces and marries a girl that you suspect won't let you fish again. Do you take your gun and invade the room with a view? No because you don't have the right to do so. The police will come, arrest you, you will be condamned and put to jail. For nations it's different. There is no police. There is no law that forbids war. People who make war in some case may receive the peace Nobel prize. I also would like to see more transparency. If Crimea is so important for Russia, tell it. Speak. Learn to divulgate your plans, put your papers open on the table and discuss with other parties (countries). Why is it always needed to wait for hundred, thousand, millions of deaths before doing that?

Like 2010 top number 2?

Yes, on my screen in Mozilla it shows like this Go to "more reply options" on the down right, then "attach files"

Remi's moto is :"It's when you do anything that you become anyone" Enjoy http://www.youtube.com/watch?v=yTOTPS9eeNw

I disagree. (And I am not alone, see below) To me, time does not flow. What happens is that WE are "moving" in time. Etienne Klein wrote (sorry for my word-by-word translation from french) Etienne Klein is a physicist and phd in philosophy, working at CEA (French Commissariat a l’Energie Atomique) and professor at Ecole Centrale de Paris. Copy-pasted from an old long thread on the same subject. page 7 post#125. IMHO it is an important point about a basic understanding of time

Right. Movement through time. It sounds so obvious as you stated. Most people do not accept that fact though. ------------------ Explaining. It is also considered as a difference between space & time. In space, objects change coordinates. In time, it is often considered that objects do not change coordinates properly: objects are considered to extend from one coordinate to another. people use to say: the moon existed yesterday, it exist today, the moon will exist tomorrow. So, the Moon's existence in time extends from yesterday to tomorrow. As if they were 3 moons (in fact an infinity of moons, each one for any instant of time). And based on this understanding, people create fairy tales on how it would be possible to go back and visit Moon number one in the past. Which is completely false IMHO. My point is that "movement in time" should be considered exactly as "movement in space". There is no difference. It is a change in coordinates. If the Moon is there today, it means that there is no "other moon" in some "other time" in the past. That "old moon" is gone, it has change coordinates. I hope it is not too difficult to understand and accept.

Yes. I feel that Kramer was talking about planets. The title of the thread is misleading, he was over-excited with his "discovery" I presume.

What is the other source? 1. what makes a planet orbit? 2. what makes a planet rotate?

IMHO the main obstacle in the discussion is that very few of us are ready to admit that time and space might be the one and same thing. Schneibster may shout it another hundred times, the message will not be heard. That's because we are stuck with the obvious differences between time and space. Like That is a very common difference. But I think it is wrong to consider that there is such a difference. IMHO there is not. Time is a single dimension that goes one-way: we call that "the arrow of time". Time is always positive. Now, if you extract from 3D space one of the single dimensions of space, what do you get: you get distance. And, surprise, distance is also always positive. There is no negative distance, as there is no negative time. One will say then: how is it possible to take an object, displace it, and put it back in place? (something that you cannot do in time) IMHO the only way to understand the consequence of Relativity, is to say that it is not possible to displace an object and then put it back in place. That's why I think we are mystified by space. We are blinded by something we feel is evidence, and Schneibster must be correct. I am very sad. I hope he will come back.

That is correct. What does that mean concerning the content of the past light cone? Can I directly observe the inside part of the past light cone?

Funny. You were too late to write "No"?

Sure. But why can I not observe directly myself as I was a second ago? Or a minute ago?, Or an hour ago? All those points lie inside the past light cone and I cannot directly observe them. We can see the past, yes. But not ALL the past. i mean: the part of the past that we can observe is a direct function of the distance.

If you wish. The diagram is not intended to provide a definition of time. It is intended to get a grasp on the concepts of Past present Future. The weird thing on this graph is the following: if the Past light Cone is observable, why am I not able to directly observe myself in my own past?

It is not a definition of time, that part has been abandonned. It is "working" with time as we (don't) know it

What we have for sure is this: What we call "physical reality" is inside the past light cone. All the rest, especially the so-called "Present" is knowable through duration. As time passes by, the observer translates higher on the time axis (he moves up) and operates a "scanning" of the world around him.

So far different units for Time & Space. Time on the vertical axis in seconds. Space on the horizontal hyperplane has units of meters. Scaled so that Speed Of Light can be represented as a line 45 degrees between space & time axis.

True. I believe we are mystified by space. We have understood nothing. None of us. I don't think so. We haven't reach the edge of human understanding. Past, present & future. I need a diagram. All information coming from a distance need time to reach the observer. So if I put myself (the observer) in the centre of the diagram, all information (radiations, forces, wathever physical) comes from the Past. No information at a distance can reach the observer in zero time: no outside information from the present. The only thing I can observe in the Present is the thing at zero distance: that's me. So, _in the Present is me, the observer, and nothing else. _in the past is everything I can observe at a distance. _in the future I can observe nothing.

Should be posted in 36 days from now : the theory of the stork rises again. http://www.psychologytoday.com/blog/perfect-health-diet/201203/the-theory-the-stork-rises-again

No need to be harsh, Strange. Permutating the word "change" with "time" does not shed light on the understanding of Time IMHO. And you should admit that the 4 dimensional spacetime that drives to the concept of a static universe is not clearly understandable when comparing with everyday experience.

Relativity tells us that Space & Time form a continuuum, IOW that Space & Time are 2 sides of a same thing. If Space can be rotated in time, and reversely, and if as you say "It's its relations to the space dimensions that make it temporal or spatial", doesn't that mean that, in the end, Time and Space are exactly the same thing. IOW it means that when I look at an object at a specific distance, I look at an object at a specific time. Which is exactly what happens.

For some mysterious reason I cannot post images created by picture editing programs. I always must make a printscreen. The printscreen (jpg) is accepted.