michel123456

Yes relativity is baffling. In this case, Galilean Relativity. Not even Einsteinian. There is no need to become angry. The same people who say that velocity is relative are the ones who say that the velocity of light is absolute. Don't be surprised that people don't get it just like that. What is motion is a very good question. To me, motion is a way to harvest energy.

You are correct. Nobody speaks about the speed of space neither

Good question. As far as I know, in all theories with more than 4 dimensions, all supplementary dimensions are spatial. It is believed that there is only 1 temporal dimension. That is because there are some fundamental differences between Space & Time.

Speed is defined by units of distance divided by units of time. It is the number of meters you travel in one second. m/s The "speed" of time (wrong word as mentioned above) would be the reverse of speed. It would be defined as units of time divided by units of distance. It would be the number of seconds you "travel" (you spend) in one meter. s/m But I am not really sure if that means something physically. ---------------------------- A quick google search (seconds divided by meter) does not return anything corresponding.

from the same path of wiki links: http://en.wikipedia.org/wiki/Dark_fluid

It is not a ridiculous principle.

No I don't want to ignore a century's worth of data. I dare to suggest that there is incompatibility because we have not made the correct interpretations. The Theory (Relativity) may be correct, the data's may be correct and support the Theory, there is still a huge gap to cover, which is interpretation. For example, we can observe a spaceship flying away from us at huge velocity and really observe the spaceship experiencing time dilation and length contraction while the spaceship's captain experiences nothing. In this case, the fact that time dilation physically occurs is part of interpretation. We have thus made experiences and find out that time dilation occurs, indeed. When we use this kind of Theory, which is fundamentally relative, in order to explain the Universe, we should keep in mind that all (ALL) results will be relative and not absolute. So it may be that the Universe appears expanding, relative to us, that the Big Bang happened 13 billion years ago, relative to us, etc. Similarly, I am suggesting that for an observer 10 billion years ago, it may be that again the universe appeared expanding to him, and that the Big bang happened 13 billion years before him. It may be that an observer 10 billion years in the future would also observe the same things than we do, and conclude exactly the same, that the Big Bang occured 13 billion years from him. IOW that the phenomenas that we call the Big Bang, and the CMB, are phenomenas explained by Relativity and as such, are horizons. IOW they are relative to the observer and have nothing to do with what an observer like the spaceship's captain, would have observed 13 billion years ago. What we have done till now is getting the data's, applying the Theory, and driving the conclusion that the data's were different in the past and will be different in the future (because it is said so from our Theory). But that is relative.

I say that any random observer should observe roughly the same thing,should establish mathematically the same laws of physics and should conclude the same things about the universe. When I say random, I mean absolutely random: that means 10 billion years in the future, 10 billion years in the past, anywhere. (because usually we think of randomness of position "now" and we forget about randomness in space and in time). Since the current accepted theory describes things differently, it means to me that we are not random observers. Sorry that bold part I cannot understand. The photons of the CMB that we catch are travelling to us at SOL and come from far away and a very distant past. The photons that you say "are still here" are the one coming from far away. In our place where we are today, there were once upon a time a plasma that emitted a huge radiation that observers some billion light years from us receive today as CMB. Now the plasma is gone and there is no emitting source of the CMB here today.

I know you may find it natural that in the history of the universe everything is changing, random events occur. The Big Bang happened 13 billion years ago so what, we are only a small blue dot lost in the immensity. So far, so good. But to imagine that we are placed in such a position that we can today observe & measure a phenomena related to the birth of the universe, and argue that future observers will not be able to observe not only the CMB, but the next galaxies, is totally insane. If our theory states that we are in a better position than them, then our theory is wrong.

Yes, the Lorentz transformation is a kind of rotation in spacetime. What i understand (maybe I am wrong on this) is that (a part of) what is space for an observer is (a part of) time for another. What i also understand is that the rotation is such that space & time coincide for something traveling at Speed Of Light. And that the axis of time & space cannot switch.

That covers the question. That the CMB is a radiation coming from a plasma at an epoch before atoms were created, everywhere. And that our galaxy, the Sun & the Earth were formed roughly where we are today in order to be able to receive this radiation that was emitted so long ago at a distance we could not have been able to travel from. Don't you find this result completely insane? That future observers will have no way to detect the CMB, or even to detect the universe?

No that does not help really. We are the archer, The cmb is the arrow. Rephrasing the question: If the CMB was emitted a long time ago at the same time with the matter that the universe is made up. how can we see it? Imagine switching a light bulb on, then switch it off, then go on travelling for 12 billion years and catching the photons from the light bulb.

Here is the question At the Big Bang, the universe were created and started expanding. The universe includes us, the Earth, the Milky way galaxy, and also the CMB. So the question is: how is it possible for us to observe a radiation that was emitted at the time we were born? It looks like the archer running faster and being killed by its own arrow.

If you take a spacetime diagram, X axis is space & Y axis is time. The observer is at the intersection of the 2 axes. An object in constant motion is represented by a diagonal line, the velocity is represented by the angle of the line. A rotation of the line represents a change in the state of motion (acceleration). For any other observer in different state of motion the time & space axis are tilted (rotated). Which means that what time is for an observer becomes a part of space for another, and vice-versa. http://upload.wikimedia.org/wikipedia/commons/thumb/d/db/Minkowski_lightcone_lorentztransform.svg/588px-Minkowski_lightcone_lorentztransform.svg.png So, when 2 observers are in different state of motion, for them the time (and space) axis are rotated. When they change their state of motation then rotation takes place. You understand negative as it was negative direction. But you can have space without thinking about direction. Simply "space". I don;t know anything like "negative space" For example, in hypothetical "negative space", one could also have a bunch of directions (and positions)

Well, If for a different observer what is space for him is time to me, it looks like a rotation where, when rotated, time becomes space. Show me negative space. There is no such a thing.

how is that possible? Profile Views 53,312 today.

I think it is a wrong interpretation. Negative direction is simply a rotation 180 degrees, it is not exactly a negative. Truly negative space would be negative distance and we know that negative distance does not exist.

You have a model that predicts there are fishes in the sea. You fish a dolphin. ----------------------- To say it otherwise. If I build a model that predicts CMB but my model says that temp is a sinusoidal function (raising and lowing), would CMB become a "proof" of my model?

I prefer your last statement.

Lets put it otherways. Do you agree with the following statement:

O.K. We are measuring today that the CMB has a specific temperature. That is an evidence. We cannot measure what temperature of the CMB a long time ago, that is a lack of evidence and I understand that we are obliged to work out a model with that lack of information. I also understand that any proposed model must "insert" the fact that the CMB has the specific temperature. But I understand also that the only fact that we really know, the only evidence we have at hand, is today's CMBR temperature. We cannot say: the CMB was higher in the past and thus blah blah blah. We must say that our model "predicts" a higher CMB temperature in the past. IOW the higher temp of CMB in the past is not an element that supports our current model, it is an assumption that derives from our model. For example Is a false assumption.

+1 in my fake rep point sytem for having posted in speculations by yourself. Anyway, even if your speculation is correct, it does not answer the question where does that "stuff" comes from.

That is not evidence.

Excuse my ignorance but what evidence have we that 10 billion years ago the CMB was measured more than it is measured today?

1 photon? Are photons used to determine average mass density?