Mordred Posted November 30, 2014 Posted November 30, 2014 As Strange mentioned the FLRW metric is an exact solution to the Eintein field equations. However showing how is a rather complex matter. The best article is a 995 page technical article. Unfortunately advanced. Outside of textbooks and the other articles on my free non profit website it is the best I can offer. The problem is this particular text requires a good understanding of math and differential geometry. Some of the other articles on my site less so however this is the one that answers specifically the GR to FLRW relation. It will take time to study I would recommend the FAQ Strange posted as well as working downward the links in my Sig prior to reading this link if you cannot afford a textbook. http://www.blau.itp.unibe.ch/newlecturesGR.pdf If you have a strong interest the best intro textbook I ever read out of 27 of them is Barbers Rydens "Introductory to Cosmology" followed by "Modern Cosmology" by Scott Dodelson to simplify the math Roads to Reality by Sir Roger Penrose. (This is a non specific model math breakdown at high school level text) How do you define kinetic energy and momentum of an escaping galaxy? This last part needs addressing as it is vital. First off we have to cover a few aspects. 1 expansion is homogeneous and isotropic. (No preferred location or direction. In other words uniform) Now the FLRW metric also includes the ideal gas laws. Treat every energy density contributor as a gas with a pressure contribution according to its equation of state (cosmology) Link added at the end. Now as expansion is uniform pressure exerts An equal uniform force upon those galaxies in all directions equally. So the galaxies themselves experience no greater force in a particular direction. Therefore they themselves gain no intertia or kinetic energy. Instead the cosmological constant aka dark energy can only affect the regions between galaxies or gravitationally bound objects. Sounds counter intuitive but it helps to think of energy density as pressure and the universe as an ideal gas. ,(this is how the FLRW metric is designed with GR added.) As stated start with the link Strange posted earlier. The tutorial on that site is excellent. Then read downward the links on my site. The articles were chosen to teach textbook cosmology for those that cannot buy textbooks http://en.m.wikipedia.org/wiki/Equation_of_state_(cosmology) Forgot to add one key concept to understand is that no galaxy gains inertia due to expansion. Instead the volume of space between galaxies simply increased so GR is not violated. Also as mentioned recessive velocity required a huge distance measurement between observer and object measured to show a distance dependant recessive velocity in excess of c. (Past Hubbled sphere) 1
michel123456 Posted November 30, 2014 Posted November 30, 2014 (edited) Tell you what. If Michel wishes to state that he accepts the orthodox view, but simply does not understand it, then I shall offer a full apology. Otherwise my conclusion remains. I cannot accept what I cannot understand, that is as simple as that. You don't need to apology either, i understand your POV about peer reviewed theories, I don't follow the same methodology. My POV is that nobody so far has been able to answer some very simple questions. One of this question is the one in my previous post: How is it possible that 2 far away galaxies A & B as observed on opposite sides of the sky were once together? density is not a good answer for 2 good reasons 1. higher density is not observed 2. it does not answer the question. How is it possible that galaxies C & D, more ancient than A & B, look in the sky at an increased distance from each other although our Theory states that they should be closer? Edited November 30, 2014 by michel123456
Mordred Posted November 30, 2014 Posted November 30, 2014 If you want to understand it then take the time to read the material provided. The first section of links is no math or little math needed. In all honesty most of the material provided is entry cosmology level.
Mordred Posted November 30, 2014 Posted November 30, 2014 By the way higher density is a requirement of a smaller universe in the past than it is today. This conforms to the thermodynamic laws. Google the term "ideal gas laws in Cosmology". If you wish further detail outside the material I provided. The links contain everything stated on this thread. Take the time to learn it. "I don't understand it" therefore don't accept it is plain wrong. Read the material and post specific questions on it. Include the article and page we can easily step you through it if you truly want to learn. It would be a pleasure. After all that is the only reason why I visit forums. To help others learn. I never ask questions. Why is simply due to buying and studying over 40 textbooks. As well as spending 15 years of self study. I come here to help others only... so please feel free to show us a willingness to learn. I would be more than happy to help with that proven willingness
Strange Posted November 30, 2014 Posted November 30, 2014 (edited) I cannot accept what I cannot understand, that is as simple as that. That could make a you a thoughtful person. However, there is a difference between "not accepting" and "rejecting". There is a difference between "cannot understand" and "refuse to understand". Your rejection of the theory and the evidence because you refuse to understand it, simply makes you a fool. My POV is that nobody so far has been able to answer some very simple questions. Only because you reject the answers. How is it possible that 2 far away galaxies A & B as observed on opposite sides of the sky were once together? If you look at A and B, and every other suitably distant galaxy, you will find they are all moving apart from one another. The rate at which they are moving apart from one another is proportional to how far apart they are. This shows an even expansion of space between them. This fairly clearly means that, in the past, they were closer together (and, of course, that now they are further apart than we currently see them). You appear to reject this because you think it represents a static snaphsot of the way the universe is now. 1. higher density is not observed Yes it is. It is directly observed as the CMB. That is why that was the evidence that killed the steady state model(s) stone dead. How is it possible that galaxies C & D, more ancient than A & B, look in the sky at an increased distance from each other although our Theory states that they should be closer? Because the theory states no such thing. You are making up your own "theory" based on nothing but ignorance and misunderstanding and then complaining the evidence doesn't fit it. Brilliant. Edited November 30, 2014 by Strange
Mordred Posted November 30, 2014 Posted November 30, 2014 Lol my post got split up by the other relevant comments guess we have some active members on this thread
swansont Posted November 30, 2014 Posted November 30, 2014 ! Moderator Note Several off-topic posts have been split off to the trash. Accusations that someone is not sincere or is not making an effort to understand are inappropriate, and, ironically, may stem from not making enough of an effort to weed out the source of the misunderstanding. Posts on general attitude of responses has been split to http://www.scienceforums.net/topic/86705-attitude-in-posts-split-from-big-bang-and-ether/ I cannot accept what I cannot understand, that is as simple as that.You don't need to apology either, i understand your POV about peer reviewed theories, I don't follow the same methodology.My POV is that nobody so far has been able to answer some very simple questions.One of this question is the one in my previous post:How is it possible that 2 far away galaxies A & B as observed on opposite sides of the sky were once together?density is not a good answer for 2 good reasons1. higher density is not observed2. it does not answer the question.How is it possible that galaxies C & D, more ancient than A & B, look in the sky at an increased distance from each other although our Theory states that they should be closer? Simple questions do not always have simple answers. However, A and B are both observed to be moving away from us. If we consider earlier times, they must have been closer to us and closer together. How does one come to any other conclusion than that? Accounting for their distance and velocity, we would all have been very close together at some point in the remote past. If we were closer together, the density would have been higher.
DimaMazin Posted November 30, 2014 Author Posted November 30, 2014 I am curious why you ask this. I suppose you could define the kinetic energy and momentum in the same way you would for any other object. But I'm not sure it has any real meaning, because the apparent movement is purely due to the metric expansion of space. Is that a scientific answer?Didn't big bang create kinetic energy for the escaping galaxies?
michel123456 Posted November 30, 2014 Posted November 30, 2014 Because the theory states no such thing. You are making up your own "theory" based on nothing but ignorance and misunderstanding and then complaining the evidence doesn't fit it. Brilliant. ????? Look, the most impressive answer I have found so far is a diagram from Ned Wright's tutorials Simple questions do not always have simple answers. However, A and B are both observed to be moving away from us. If we consider earlier times, they must have been closer to us and closer together. How does one come to any other conclusion than that? Accounting for their distance and velocity, we would all have been very close together at some point in the remote past. If we were closer together, the density would have been higher. That looks very logical. However, when you look to the sky, don't we look to the past? the configuration is the following, with the letter Y (You) as the observer: C--A-Y-B--D The BBT states that C & D were (are, because we are actually observing the past) closer to each other than A & B. You can find tricks for that to happen. For example you can write the configuration down onto a sheet of paper then roll it so that C & D are in contact. You can also plot the positions on Ned's diagram. However, in real 3D (4D) world, you cannot do that. If you rewind back universe's evolution, C and D will always remain further away from each other than A and B. The initial configuration will never revert upside-down like a sock. It will never become (I have some difficulty to write it down) Y-A--CD--B-(Y?) where CD are close to the Big Bang.
swansont Posted November 30, 2014 Posted November 30, 2014 That looks very logical. Yes. Did that answer your question? However, when you look to the sky, don't we look to the past? the configuration is the following, with the letter Y (You) as the observer: C--A-Y-B--D The BBT states that C & D were (are, because we are actually observing the past) closer to each other than A & B. No, it doesn't. What did you read that made you think this is the case?
Strange Posted November 30, 2014 Posted November 30, 2014 the configuration is the following, with the letter Y (You) as the observer: C--A-Y-B--D The BBT states that C & D were (are, because we are actually observing the past) closer to each other than A & B. You suggest that the universe turned itself inside out at some point? If you are making up stuff like this, no wonder you are confused! If you rewind back universe's evolution, C and D will always remain further away from each other than A and B. Correct.
michel123456 Posted November 30, 2014 Posted November 30, 2014 (edited) Yes. Did that answer your question?No. No, it doesn't. What did you read that made you think this is the case? Because we are looking into the past. Where am I wrong in my statements? Correct.And that makes sense to you? C & D are closer to the BB. Edited November 30, 2014 by michel123456
Strange Posted November 30, 2014 Posted November 30, 2014 And that makes sense to you? It makes more sense than the idea the universe has turned inside out. When did that happen, exactly?
swansont Posted November 30, 2014 Posted November 30, 2014 No. Help me out then. If two people are observed to be moving away from you, one moving east and one moving west, what is that doesn't make sense when I say at earlier times, they were closer to you and, by extension, to each other? Please try and address only that, without changing the conditions of the example. Because we are looking into the past. Where am I wrong in my statements? And that matters for what reason? You are wrong when you claim that the far-away galaxies must have passed by nearer galaxies to get there, and that BBT says this to be the case. You did not provide a link to where anyone has claimed this to be true. You've also apparently denied that basic kinematics is true, and there's no way one can proceed in understanding from that as a starting point. And that makes sense to you? C & D are closer to the BB. The BB is when A, B, C and D are all co-located.
michel123456 Posted November 30, 2014 Posted November 30, 2014 (edited) Help me out then. If two people are observed to be moving away from you, one moving east and one moving west, what is that doesn't make sense when I say at earlier times, they were closer to you and, by extension, to each other? Please try and address only that, without changing the conditions of the example. That makes sense. And that matters for what reason? I will address this later if you don't mind. It makes more sense than the idea the universe has turned inside out. When did that happen, exactly? If it makes sense to you then you don't have to bother with the inside-out thing. Edited November 30, 2014 by michel123456
Mordred Posted November 30, 2014 Posted November 30, 2014 Have you looked at the balloon analogy? Take a balloon draw some dots on it. Then inflate it. Don't concern yourself with what is inside or outside the balloon. Were only concerned with how the dots move. Notice how they seperate with evenly from each other with no change in angle between any of the dots. How galaxies move from each other works the same way as those dots.
michel123456 Posted November 30, 2014 Posted November 30, 2014 Have you looked at the balloon analogy? Yes. http://www.scienceforums.net/topic/44385-quibbles-with-the-balloon-analogy/?p=518081
nullus Posted November 30, 2014 Posted November 30, 2014 ok thank you all, and what I shell give you for that? I was understand the lesson.
Mordred Posted November 30, 2014 Posted November 30, 2014 Ah I see well the balloon analogy itself is meant to merely model a 2d representation of how galaxies seperate. Nothing more than that. There is a few details left out in that thread. Mainly that per m^3 the energy density of the cosmological constant is extremely weak. Roughly [latex]6.0 *10^{-10}[/latex] joules per cubic meter. This weak energy density per cubic meter is easily overpowered by local gravity as well as the strong force 1
nullus Posted November 30, 2014 Posted November 30, 2014 Can I give you something for such an incredibly huge help for me ???I just do not know how to show my respect to all of you..
nullus Posted November 30, 2014 Posted November 30, 2014 Then just a BIG BIG BIG BIG Thank you all. 2
Strange Posted November 30, 2014 Posted November 30, 2014 Then just a BIG BIG BIG BIG Thank you all. BANG!
Mordred Posted December 1, 2014 Posted December 1, 2014 BANG! Pretty bright light..ouch that's hot Lol
DimaMazin Posted December 1, 2014 Author Posted December 1, 2014 BANG! What was a kinetic energy of big bang? If there was no KE then we dont need BB. Simply a merge of masses creates additional space. For example : when you turn hydrogen into helium then you create additional space, which expands universe.
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