michel123456

I think it would be interesting to have a history cursus about human condition a few decades from now. I believe a small percentage of humanity living in privileged countries today enjoy a life into a "pays de cocagne" without having full conscience of it. The tremendous majority of human kind was and is still living under abominable conditions. So yes the world has become a better place to live in, but not everywhere, and not for everyone. In the country I live today, part of Europe, it was not surprising 70 years ago to encounter bare foot inhabitants in the villages, since shoes were a luxury. Many houses outiside towns had no bathroom till 50 years ago. In Belgium, at the right core of Europe, I remember farms in the villages without electricity, it was in the 60'ies. I remember as a child visiting a family in France, they were so rich they had 2 cars, it was unbelievable. The first tv I remember at home was black & white, into a piece of furniture with a key hidden by my parents, and emissions of the national channel began at six IIRC and ended around eleven. They are uncountable examples. These are not only technological, but also social, since technology has been spead all around, and not reserved only for Kings. What changes are going to be made? I don't know, but new generations must be extremally carefull. Over-developement increases the gap between "normal people" (the huge majority) and the few "privileged" ones. It is both injust and dangerous.

On the contrary. My field of interest is everything. Of course I cannot manage everything, but IMHO it is not necessary to focus on one field of science. Only if you want to become a specialist in this particular field. There are interesting things everywhere. And one of the most interesting thing is the interconnection between apparently totally different fields of knowledge. And I will not go back to university.

Reason is what says to me not to respond to this question.

There is an avalanche of information in your links. Most of it is highly speculative. There is no way to discuss it as a whole. I see you are a supporter of transhumanism.. Maybe you should start a thread on the subject if you want to get a reaction. ---------------- edit. Maybe transhumanism is even too complex. Human Enhancement perhaps?

Not exactly but you are close. Read your question again.

I think a free mind in quest of God don't have to hurry. No answer is obvious: if it were, we would all be enlightened. The good way is to look at reality en face. IMHO there is no need for excuses like "God is good" when your child is dying or your wife raped, tortured, killed. Reality is there, it is the starting point of everything and we have to deal with it. But that is only my opinion. Shortly, I think we have an incredible chance to live at a time & at a place where free investigation is allowed (is it?), so I vote freedom of quest. And I vote against blind faith.

I do nothing of the above. ------------------------------- Thank you, I just got reputation 100. What do I win?

No one will help you. You must rely on your own capacities. What are your fields of interest?

I know dunes move several meters a year, according to local conditions. A paper I found on the net is here and another here and another here After some search, I am amazed of how little research has been made on the subject. About speed I found here that: "In his studies of the Kelso dunes, Sharp (1963;1966) also found that ripples move downwind at relatively fast rates. At a threshold velocity of 18 kph, ripples advanced downwind at a rate of .9cm per minute, with the rate increasing to 8 cm per minute during the strongest winds. Consequently, Sharp concluded the "adjustment in size, shape and spacing can presumably occur rapidly in response to differences in velocity" (1963, p. 631). From an initially flat surface, ripples can form a complete pattern in ten minutes (in a 48 kph wind) and can flatten out, reform or change direction as quickly. This rapid formation and movement of sand ripples also contributes to a large volume of sand movement. At one test plot, Sharp discovered that, in one hour's time, 48 kph winds could move 6000 pounds of sand across a 32-meter line."

Interesting comment. That make my statements completely wrong. I should have stated: (aouch its harder than i first thought) _Distance (spacelike interval in spacetime) is positive or negative, when squared is positive. _Duration (timelike interval in spacetime) is imaginary, when squared is negative. _Distance for light (lightlike interval in spacetime) is null. That makes time perpendicular to space, isn't it? --------------------------------------------------- for a single object standing still we have: [math] x=0 [/math], [math] y=0 [/math], [math] z=0 [/math] and thus [math] s^2= -c^2t^2 [/math] (1) taking the square root we get [math] s = c t i[/math] (2) or [math] s = (ci) t[/math] (3) equation (3) is convenient because it gives a comprehensive interpretation of the timelike interval s. One would expect that for a non moving object, the interval s would be equal to t. That is not the case. What we see is that s is equal to t multiplied by a coefficient equal to ci. Well, there is a way to make the equation ressemble what was expected, but the price to pay is inacceptable: if and only if [math] c= i [/math] then equation (3) becomes [math] s = -t [/math] (4) But [math] c= i [/math] is wrong.

post cancelled

Sorry for misunderstanding. I am tired of discussing moving bodies, and since I have difficulties on understanding simple things, I focus on objects standing at rest in the same FOR. For those 2 objects: 1.the distance between them is positive. I guess everyone agree on this. 2.the time between them is negative. That is the result I understand from the precedent discussion. Do you agree?

Are you sure your pipeline will remain burried all time long at the same depth? As much as I know, sand dunes are moving. IMHO you must work on 100% exposure. Maybe worse, your coating must resist the abrasive force of sand under wind, and exposure to U.V.

I am so sorry, but I don't understand why it is meaningless to include length contraction. As i said in post#1 At which you seemed to agree. I don't understand how a theoretical equation about time dilation ignores completely distance contraction.

You said (emphasis mine) I am confused.

Thank you. I understand quickly but you have to explain for a long time. Now I will tell you what I understand. _Distance (spacelike interval in spacetime) is positive. _Duration (timelike interval in spacetime) is negative. _Distance for light (lightlike interval in spacetime) is null. Is it correct?

Why use SR instead of GR?

called hybrids Not being an expert at all, after some search, I see that Homo Sapiens is "the only living species in the Homo genus of bipedal primates in Hominidae, the great ape family". (from wiki) Since hybridation works mainly between members of the same genus, I doubt breeding a human with an ape would work.

You are talking about a spherical universe.

You can also travel at night continuously. At equator (which is rather stupid) you'll need to go faster than a jumbo jet. But if you stay at the North pole in winter period, you can stay at home. The sun will not rise tomorrow. For you. And since "the sun rise" is a relative observational event different for each observator, you can also die today, then for you the sun will not rise tomorrow, because there will be no tomorrow. For you. Or humans could also change the shape of the planet building a Globus Cassus for example.

Google the first 4 words of your question.

No, I asked why [math] s^2=x^2+y^2+z^2-c^2t^2 [/math] I am patient. You will say I am stubborn. My question is not about the meaning of "interval", it about zero. "spacetime interval" has a meaning. [math] s^2=0 [/math] and of course [math] ds^2=0 [/math] Why do you call zero "spacetime interval"? How did that come out? When the result of an operation is zero, It is usually called "null result", not "something". Is that more clear as a question?

And the same goes for a body in gravitational potential. (I will split the thread because there is another interesting point raising from your answer). I don't see any length contraction in the above equation. Distances are untouched. -------------------------------------------------------------------------------- _Time discrepancies in the Hafele-Keating experiment are measured in nanoseconds. _1 nanosecond corresponds to approx 0,3m (calculated by multiplying 1 ns by the speed of light) _The larger theoretical time discrepancy due to gravitation in this experiment is 179 nanoseconds. (see here) which corresponds to a distance of 179 x 0,3m = 53,7m. Which is very small in correspondance with the approximations of the experiment: "This corresponds to an average height of 8900 m, a reasonable flight altitude for a commercial airline." and "since to the level of the approximations used, the height of the aircraft does not significantly change the radius R." (from the same link) under Kinematic Time shift calculation" after the "The problem encountered with measuring the difference between a surface clock and one on an aircraft is that(...)" ------------------------------------------------------------------------- in this equation (from wiki's article here) under "Gravitation" "Where c = speed of light, h = height, g=acceleration of gravity, v = velocity, ω = angular velocity of Earth's rotation and τ represents the duration/distance of a section of the flight. The effects are summed over the entire flight, since the parameters will change with time." I see no factor influencing the value of h=height.

You are trying to flood the fish. (to cloud the issue). Duration can be represented in a Minkowski diagram without the use of elaborated ST.

Swansont wrote: I am focusing on the "I see your clock as running slow" part. For a moving body, the "clock running slower" corresponds also to a change in distance (due to motion) and to a change "in-distance" (due to length contraction) But for an object inside a gravitational potential, where the change due to motion is null, what does that mean? Does that mean that 1, indeed, the other clock runs slower, so that as much I wait, the discrepancy will rise? no matter the fact that distance due to motion remains the same? or 2, there is a gap between the 2 clocks and this gap will remain the same no matter how long we'll wait?