The relation beween black holes and dark matter.

SpeedFreek · Jan 22, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>Speedfreak, his point is correct, if the volume increased by 10. then the distances between points will not also increase by a factor of 10.  Your idea is dead on it is just that you are just forgeting that volume cubed and the distance is not.volume increases from 10m to 100m.10m = 4/3pi*r^3    ::  r = 1.34m100m = 4/3pir^3    :: r = 2.88mThe linear distance does not increase by a factor of 10 Posted by origin</DIV>Yes, Neils point is correct as I already said, so I obviously need to reword my explanation! (Anyone know a good editor?)The basic point is that if the cosmic scale factor (1+z) doubles, then all distances double and the radius, the diameter, the size of the universe doubles. If the scale factor is 10, then all distances increase 10 times and the diameter of the universe is 10 times bigger. If the universe is now 1100 times larger (in diameter) than when the CMBR was emitted, then the metric that defines distance has increased 1100 times and a coordinate that is co-moving with the expansion is now 1100 times further away than it was when the CMBR was emitted. It is my terminology that is confusing the issue, so I will have to avoid using the word "volume" and just call it the diameter of the universe instead.If my conceptual 3D grid, which expands with the universe, increases in diameter (now that sounds wrong, how can a boundless grid have a diameter? But if I use the word "size" does it imply I am talking about the volume of the grid?) by a factor of 10, then all intersection points become 10 times more distant from their neighbouring points, and the whole grid is now 10 times larger than it was to begin with. Any two points on that grid, however far away from each other they were to begin with, they end up 10 times more distant. I was always talking about the distance measure within a volume of space. Obviously, I introduced a problem when I said the "volume grows to 10 times its original size". I meant the distance across that volume, the diameter of that volume, not the volume of the volume! Who on Earth talks about the volume of the universe?! I was talking about a volume of space increasing in size, not the volume of space increasing in size. But it was my bad wording that caused this mess as the word could be taken in the wrong context. Thanks for the heads-up guys, it took me a while to realise what the problem was. I was just modelling an expanding volume of space by embedding a grid in it and talking in terms of the distance measure for that grid. I will in future try to avoid using the word volume when describing distance across a volume of space. I can see how using the word is misleading. Just as long as you understand that the expanding grid model is a useful tool for showing how the further away an object is, the faster it will recede if the whole, err.. thing increases in size equally throughout. <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" /> <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

origin · Jan 25, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>Yes, Neils point is correct as I already said, so I obviously need to reword my explanation! (Anyone know a good editor?)The basic point is that if the cosmic scale factor (1+z) doubles, then all distances double and the radius, the diameter, the size of the universe doubles. If the scale factor is 10, then all distances increase 10 times and the diameter of the universe is 10 times bigger. If the universe is now 1100 times larger (in diameter) than when the CMBR was emitted, then the metric that defines distance has increased 1100 times and a coordinate that is co-moving with the expansion is now 1100 times further away than it was when the CMBR was emitted. It is my terminology that is confusing the issue, so I will have to avoid using the word "volume" and just call it the diameter of the universe instead.If my conceptual 3D grid, which expands with the universe, increases in diameter (now that sounds wrong, how can a boundless grid have a diameter? But if I use the word "size" does it imply I am talking about the volume of the grid?) by a factor of 10, then all intersection points become 10 times more distant from their neighbouring points, and the whole grid is now 10 times larger than it was to begin with. Any two points on that grid, however far away from each other they were to begin with, they end up 10 times more distant. I was always talking about the distance measure within a volume of space. Obviously, I introduced a problem when I said the "volume grows to 10 times its original size". I meant the distance across that volume, the diameter of that volume, not the volume of the volume! Who on Earth talks about the volume of the universe?! I was talking about a volume of space increasing in size, not the volume of space increasing in size. But it was my bad wording that caused this mess as the word could be taken in the wrong context. Thanks for the heads-up guys, it took me a while to realise what the problem was. I was just modelling an expanding volume of space by embedding a grid in it and talking in terms of the distance measure for that grid. I will in future try to avoid using the word volume when describing distance across a volume of space. I can see how using the word is misleading. Just as long as you understand that the expanding grid model is a useful tool for showing how the further away an object is, the faster it will recede if the whole, err.. thing increases in size equally throughout. Posted by SpeedFreek</DIV>I'm sorry, somehow I misread your post!  I feel like a goof, but I'm sure it won't be the last time. <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-foot-in-mouth.gif" border="0" alt="Foot in mouth" title="Foot in mouth" /> <div class="Discussion_UserSignature"> </div>

origin · Jan 25, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>Yes, Neils point is correct as I already said, so I obviously need to reword my explanation! (Anyone know a good editor?)The basic point is that if the cosmic scale factor (1+z) doubles, then all distances double and the radius, the diameter, the size of the universe doubles. If the scale factor is 10, then all distances increase 10 times and the diameter of the universe is 10 times bigger. If the universe is now 1100 times larger (in diameter) than when the CMBR was emitted, then the metric that defines distance has increased 1100 times and a coordinate that is co-moving with the expansion is now 1100 times further away than it was when the CMBR was emitted. It is my terminology that is confusing the issue, so I will have to avoid using the word "volume" and just call it the diameter of the universe instead.If my conceptual 3D grid, which expands with the universe, increases in diameter (now that sounds wrong, how can a boundless grid have a diameter? But if I use the word "size" does it imply I am talking about the volume of the grid?) by a factor of 10, then all intersection points become 10 times more distant from their neighbouring points, and the whole grid is now 10 times larger than it was to begin with. Any two points on that grid, however far away from each other they were to begin with, they end up 10 times more distant. I was always talking about the distance measure within a volume of space. Obviously, I introduced a problem when I said the "volume grows to 10 times its original size". I meant the distance across that volume, the diameter of that volume, not the volume of the volume! Who on Earth talks about the volume of the universe?! I was talking about a volume of space increasing in size, not the volume of space increasing in size. But it was my bad wording that caused this mess as the word could be taken in the wrong context. Thanks for the heads-up guys, it took me a while to realise what the problem was. I was just modelling an expanding volume of space by embedding a grid in it and talking in terms of the distance measure for that grid. I will in future try to avoid using the word volume when describing distance across a volume of space. I can see how using the word is misleading. Just as long as you understand that the expanding grid model is a useful tool for showing how the further away an object is, the faster it will recede if the whole, err.. thing increases in size equally throughout. Posted by SpeedFreek</DIV>I'm sorry, somehow I misread your post!  I feel like a goof, but I'm sure it won't be the last time. <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-foot-in-mouth.gif" border="0" alt="Foot in mouth" title="Foot in mouth" /> <div class="Discussion_UserSignature"> </div>

SpeedFreek · Jan 25, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>I'm sorry, somehow I misread your post!  I feel like a goof, but I'm sure it won't be the last time. Posted by origin</DIV>No need to apologise, it was my usage of the word "volume" that confused the issue. I used it simply to describe a three dimensional area, not to quantify that area, but it is really easy to word it badly and confuse the reader, which is what I did. I am still refining my explanations! <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" />As long you understand the concept I was trying to convey in the end, that's all that matters.   <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

SpeedFreek · Jan 25, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>I'm sorry, somehow I misread your post!  I feel like a goof, but I'm sure it won't be the last time. Posted by origin</DIV>No need to apologise, it was my usage of the word "volume" that confused the issue. I used it simply to describe a three dimensional area, not to quantify that area, but it is really easy to word it badly and confuse the reader, which is what I did. I am still refining my explanations! <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" />As long you understand the concept I was trying to convey in the end, that's all that matters.   <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

Search

The relation beween black holes and dark matter.

SpeedFreek

Guest

origin

Guest

origin

Guest

SpeedFreek

Guest

SpeedFreek

Guest

Similar threads

TRENDING THREADS

Latest posts

Moderators online

Share this page