Notices
Results 1 to 50 of 50
Like Tree9Likes
  • 2 Post By pineapples
  • 1 Post By SpeedFreek
  • 2 Post By John Galt
  • 1 Post By John Galt
  • 1 Post By shlunka
  • 1 Post By Lynx_Fox
  • 1 Post By dan hunter

Thread: Location of Earth in the Universe

  1. #1 Location of Earth in the Universe 
    New Member
    Join Date
    Nov 2012
    Posts
    1
    I have tried searching around for this but couldn't find anything basing the location on Redshift and the Big Bang. By observing direction and velocity of Redshifting objects, and with the knowledge of the Big Bang model, I thought the (approximate) location of our planet could be determined.


    Comments, links, sources, references anyone? Is Earth the centre of the Universe?


    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Senior pineapples's Avatar
    Join Date
    Apr 2011
    Location
    Ireland someplace
    Posts
    359
    I’m told there is not one central point in the universe that actually expanded out. But rather every point in the universe expanded out and is still expanding. You are actually sitting where the universe first began to expand, as is everywhere else in the universe. I won’t lie to you, as I don’t get it myself

    But what I do know is that we’re now able to say I’m the centre of the universe without me sounding arrogant!


    Strange and Halibonga like this.
    Reply With Quote  
     

  4. #3  
    Forum Freshman
    Join Date
    Nov 2012
    Posts
    11
    pinapples is right, there is no actual center of the universe, thats the idea brought about by the understanding that our universe is a constantly expanding 4-dimensional structure, you could set any point as the center of expansion and it would not matter.
    Reply With Quote  
     

  5. #4  
    New Member
    Join Date
    Nov 2012
    Location
    US
    Posts
    2
    I posted a similar question here (#20):
    A galaxy a trillion light years away...

    Based on the answer I got it would seem that the only way to derive the our position from the 'centre' (of the universe) would be to know the current boundries of the universe. Finding those boundries appear beyond our current abilities (given there -is- a boundry).

    From my limited understanding, it appears that searching for red shifted objects in all directions would only result in similar results in all directions. Perhaps some more knowlegeable folks will weigh in on this, I'm just a curious lay person.
    Reply With Quote  
     

  6. #5  
    Suspended
    Join Date
    Jan 2005
    Location
    Nashville
    Posts
    317
    Quote Originally Posted by pineapples View Post
    I’m told there is not one central point in the universe that actually expanded out. But rather every point in the universe expanded out and is still expanding. You are actually sitting where the universe first began to expand, as is everywhere else in the universe. I won’t lie to you, as I don’t get it myself

    But what I do know is that we’re now able to say I’m the centre of the universe without me sounding arrogant!
    Best explanation!
    Reply With Quote  
     

  7. #6  
    Brassica oleracea Strange's Avatar
    Join Date
    Oct 2011
    Location
    喫茶店
    Posts
    16,602
    Quote Originally Posted by Triola View Post
    Based on the answer I got it would seem that the only way to derive the our position from the 'centre' (of the universe) would be to know the current boundries of the universe. Finding those boundries appear beyond our current abilities (given there -is- a boundry).
    According to our current best theory, there is neither a centre or a boundary to the universe. So the question of our location can only be answered relative to other things: "an utterly insignificant little blue-green planet far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the galaxy".
    Without wishing to overstate my case, everything in the observable universe definitely has its origins in Northamptonshire -- Alan Moore
    Reply With Quote  
     

  8. #7  
    Moderator Moderator
    Join Date
    Nov 2011
    Location
    city of wine and roses
    Posts
    6,225
    You are actually sitting where the universe first began to expand, as is everywhere else in the universe. I won’t lie to you, as I don’t get it myself
    Yup. I remember watching Prof Brian Cox explain it - and it made perfect sense at the time. Thinking about it now, he might as well have not bothered - all that's left is an intellectual "itch" - I sort of see it and not see it at the same time.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
    Reply With Quote  
     

  9. #8  
    Forum Ph.D. merumario's Avatar
    Join Date
    Nov 2012
    Location
    nigeria
    Posts
    844
    our location in the universe can only be attributed to other things since there is no boundary and center.as strange noted above...........we are located in a galaxy called the milky way,close to the andromeda galaxy....the closest star to us is sirus.....from the night sky view from eath you see constellations...such as canis major...this is the best way you can locate our location in the universe,attribute it to other things.
    "I am sorry for making this letter longer than usual.I actually lacked the time to make it shorter."###
    Reply With Quote  
     

  10. #9  
    Suspended
    Join Date
    Nov 2012
    Location
    Apocalyptic Paradise
    Posts
    6,613
    Quote Originally Posted by merumario View Post
    this is the best way you can locate our location in the universe,attribute it to other things.
    Yes, it's all relative.
    Reply With Quote  
     

  11. #10  
    Brassica oleracea Strange's Avatar
    Join Date
    Oct 2011
    Location
    喫茶店
    Posts
    16,602
    Quote Originally Posted by adelady View Post
    [Yup. I remember watching Prof Brian Cox explain it - and it made perfect sense at the time. Thinking about it now, he might as well have not bothered - all that's left is an intellectual "itch" - I sort of see it and not see it at the same time.
    It threw me a bit when I first heard it described that way. It may help to think of it in reverse. Choose any two points (the tip of your nose and toes, or the position of our sun and Alpha Centauri) and think of what happens as the distance between them gets smaller and smaller. Eventually both those points are at the same place: gnaB giB (Big Bang backwards). So everywhere is where the big bang happened.
    Without wishing to overstate my case, everything in the observable universe definitely has its origins in Northamptonshire -- Alan Moore
    Reply With Quote  
     

  12. #11  
    Forum Senior pineapples's Avatar
    Join Date
    Apr 2011
    Location
    Ireland someplace
    Posts
    359
    Just want to confirm that I STILL don’t get it!

    Let’s say I held a measuring tape on Earth and somebody else was holding the other end of that measuring tape on another planet, in another galaxy (far far away).

    Is it that those two galaxies are not actually traveling away from each other but Space itself is actually stretching/expanding? So the measuring tape never snaps in-half, but instead, stretches/expands along with Space.

    If so, if we could hold that measuring tape between the two galaxies for ohh let’s say, 1 million years, and then decided to measure the million year old tape with the past 1 year old tape. Would they look different in size? The 1 million year old tape would appear much longer in length but skinnier?
    Reply With Quote  
     

  13. #12  
    Brassica oleracea Strange's Avatar
    Join Date
    Oct 2011
    Location
    喫茶店
    Posts
    16,602
    Quote Originally Posted by pineapples View Post
    Let’s say I held a measuring tape on Earth and somebody else was holding the other end of that measuring tape on another planet, in another galaxy (far far away).

    Is it that those two galaxies are not actually traveling away from each other but Space itself is actually stretching/expanding? So the measuring tape never snaps in-half, but instead, stretches/expands along with Space.
    They are getting further apart because the distance between them is increasing; the space in between is getting "larger". The measuring tape will snap because it is made of "stuff" and is not able to stretch that much. Space is not made of stuff, it is just a measure of the distance between things.
    Without wishing to overstate my case, everything in the observable universe definitely has its origins in Northamptonshire -- Alan Moore
    Reply With Quote  
     

  14. #13  
    Forum Senior pineapples's Avatar
    Join Date
    Apr 2011
    Location
    Ireland someplace
    Posts
    359
    Quote Originally Posted by Strange View Post
    Quote Originally Posted by pineapples View Post
    Let’s say I held a measuring tape on Earth and somebody else was holding the other end of that measuring tape on another planet, in another galaxy (far far away).

    Is it that those two galaxies are not actually traveling away from each other but Space itself is actually stretching/expanding? So the measuring tape never snaps in-half, but instead, stretches/expands along with Space.
    They are getting further apart because the distance between them is increasing; the space in between is getting "larger". The measuring tape will snap because it is made of "stuff" and is not able to stretch that much. Space is not made of stuff, it is just a measure of the distance between things.
    Cheers. Someday I’ll get a handle on it all. But without holding my breath!
    Reply With Quote  
     

  15. #14  
    Forum Ph.D. merumario's Avatar
    Join Date
    Nov 2012
    Location
    nigeria
    Posts
    844
    The tape will not snap if only it is an intrinsic property of space.
    "I am sorry for making this letter longer than usual.I actually lacked the time to make it shorter."###
    Reply With Quote  
     

  16. #15  
    Quagma SpeedFreek's Avatar
    Join Date
    Jan 2011
    Location
    London, UK
    Posts
    2,786
    It is time, once again, to make a toy model to illustrate the expansion of the universe! (Some of you will have seen me post this before)

    Now to model an expanding space we need to assign coordinates within that space. For the moment, forget about any edges to that space, we don't need edges, we just need coordinates in order to measure the expansion of space. Galaxies come later, so for now just imagine a 3 dimensional grid. At each grid intersection we will assign a coordinate, a point, a dot. Let's say each intersection point is 1 meter apart.

    Put yourself on a point somewhere in this space. Whatever axis you look along you see neighbouring points 1, 2, 3, 4, 5 etc meters away, receding off into the distance. Then we introduce some expansion. Let's say the space grows to 10 times its original size in 1 second! That seems fast perhaps, but this is just a model with easy numbers. The key thing to remember is that the grid expands with the space.

    So, here we are, still sitting on our point (but it could have been any point!) 1 second later. Now lets look along an axis. We see those neighbouring points are now 10, 20, 30, 40, 50 etc meters away. The space increased to 10 times its original size, and so did the distance between each intersection point on that grid.

    Our nearest neighbouring point has receded from 1 to 10 meters in 1 second, so it has receded at 9 meters per second. The next point away has receded from 2 to 20 meters in 1 second, so that point receded at 18 meters per second. The fifth point has moved from 5 to 50 meters away in 1 second, so that one has receded at 45 meters per second. The further away you look, the faster a point will seem to have receded!

    And the view would be the same, whatever viewpoint you choose in the grid! There is no "centre" of expansion, no origin point within that grid - the whole thing, the whole space has expanded from something where the spaces between things were really small to something where the spaces between things are much larger. The expansion of that space has carried matter and energy along for the ride.

    Remember I said the grid of points receded off into the distance.. well a point that was initially 33,000,000 meters away will have moved away to 330,000,000 meters in 1 one second, meaning that it has receded at 300,000,000 meters per second - the speed of light! Any point initially more distant than 33,000,000 meters away from another point will have receded from that point faster than the speed of light. That is the distance were an object recedes at light speed in this "little" model of expansion. If you look at a point that has receded at the speed of light, then from that point, the point you are on has receded at the speed of light. But no object would be moving through space faster than light, no photon would ever overtake another photon, it all just gets carried along by the cosmic flow.

    Now I know this is a very simple model, dealing with a simple 10 times expansion in 1 second. This might seem very different from a universe where the rate of expansion was slowing from immense speed and then starting to accelerate, but if you start your grid very small and apply different rates of expansion to that grid, incrementally, over different lengths of time, to simulate slowing it down and then speeding it up, when you look at the end result it is essentially the same. (Whenever there is a change in the rate of expansion, it is the rate of expansion for the whole grid that changes).

    You might be asking how useful this model actually is. Well you can substitute different distance measures and time-scales if you like but the principle remains. If you sprinkle galaxies throughout the grid and then expand that grid such that the galaxies move with the expansion, you would find that galaxies interact gravitationally with their near neighbours. The further apart galaxies are when they form, the less the gravitational attraction between them. If they are less than a certain distance apart, the galaxies will move towards each other and cluster together, but if there is enough distance they will be moved apart by the expansion of the universe.

    We end up with clusters of gravitationally-bound galaxies and increasing distance between the centres of those clusters, in a universe where there is no "origin point" or centre of expansion.
    Strange likes this.
    Reply With Quote  
     

  17. #16  
    Suspended
    Join Date
    Jul 2012
    Posts
    1,907
    Speedfreak.

    Does gravity have effects upon this apparant expansion of all things away from all things?
    Last edited by question for you; November 30th, 2012 at 03:35 PM.
    Reply With Quote  
     

  18. #17  
    Quagma SpeedFreek's Avatar
    Join Date
    Jan 2011
    Location
    London, UK
    Posts
    2,786
    Yes. It slows down the rate of expansion by an amount which depends on the mass/energy density of the universe. If there was enough mass/energy, the expansion would come to a halt and the universe would start to contract - this is known as a Big-Crunch scenario.

    But with the discovery that the rate of expansion was decelerating for the first 7-8 billion years of the history of the universe but has subsequently turned into an accelerating expansion, it seems there must be more than gravity at work in the universe. This is the theoretical basis for dark energy.
    Reply With Quote  
     

  19. #18  
    Forum Ph.D. merumario's Avatar
    Join Date
    Nov 2012
    Location
    nigeria
    Posts
    844
    There is no effect of gravity from your model in the expansion..but gravity was meant to slow the expansion.so that the points will draw closer by 2m in 1s...but this not the case.then there must be something pushing these points away and the farthest is moving farster as your model holds.
    "I am sorry for making this letter longer than usual.I actually lacked the time to make it shorter."###
    Reply With Quote  
     

  20. #19  
    Quagma SpeedFreek's Avatar
    Join Date
    Jan 2011
    Location
    London, UK
    Posts
    2,786
    True, I didn't describe the gravitational effect of the global mass/energy density in my toy model, as it was just an analogy to illustrate how the expansion has no centre or origin.

    QFY's question didn't seem to be directly addressing my toy model though.
    Reply With Quote  
     

  21. #20  
    Quagma SpeedFreek's Avatar
    Join Date
    Jan 2011
    Location
    London, UK
    Posts
    2,786
    Quote Originally Posted by merumario View Post
    There is no effect of gravity from your model in the expansion..but gravity was meant to slow the expansion.so that the points will draw closer by 2m in 1s...but this not the case.then there must be something pushing these points away and the farthest is moving farster as your model holds.
    Well, the "something pushing these points away" is the initial impetus of the Big-Bang. Until the 1980's this was assumed as an initial condition, but then Alan Guth gave us inflationary theory, which put the "Bang" into the Big-Bang as he put it, and provided us with a possible mechanism for this initial impetus.
    Reply With Quote  
     

  22. #21  
    Forum Ph.D. merumario's Avatar
    Join Date
    Nov 2012
    Location
    nigeria
    Posts
    844
    Quote Originally Posted by SpeedFreek View Post
    Quote Originally Posted by merumario View Post
    There is no effect of gravity from your model in the expansion..but gravity was meant to slow the expansion.so that the points will draw closer by 2m in 1s...but this not the case.then there must be something pushing these points away and the farthest is moving farster as your model holds.
    Well, the "something pushing these points away" is the initial impetus of the Big-Bang. Until the 1980's this was assumed as an initial condition, but then Alan Guth gave us inflationary theory, which put the "Bang" into the Big-Bang as he put it, and provided us with a possible mechanism for this initial impetus.
    and then its called the inflationary big bang...since this inflation accounts for the homogenity of the universe they concluded that the universe might have been a small miniscule.and thats when all the extended part interacted with each other....now from your model do you think the universe is a close system?
    "I am sorry for making this letter longer than usual.I actually lacked the time to make it shorter."###
    Reply With Quote  
     

  23. #22  
    Quagma SpeedFreek's Avatar
    Join Date
    Jan 2011
    Location
    London, UK
    Posts
    2,786
    My little toy model is not a proper cosmology, it is an analogy rather like the famous balloon analogy. It does not allow us to make predictions, it is simply meant to illustrate a set of expanding coordinates in three dimensions over time in a way that tries to avoid some the confusion that can arise when discussing the balloon analogy for expansion.

    If taken literally, the balloon analogy can make people think that the surface of the balloon is the edge of a closed universe, as they think the inside of the balloon represents the universe in three dimensions, when it is only the surface of the balloon that represents the universe in two dimensions!

    You can take my three dimensional grid and wrap it onto the balloon if you like, but this requires visualisation of a 3-Sphere, which has a three dimensional surface! Just take any line along any axis and consider it to be a very small part of a great circle that circumnavigates the universe! This is a model of a closed universe.

    Or you can consider it as flat and open, where a straight line really is a straight line and has no end.

    Our measurements and observations lead us to believe that the universe is flat, which would mean it was open. An open universe can be either finite or infinite.
    Reply With Quote  
     

  24. #23  
    Forum Ph.D. merumario's Avatar
    Join Date
    Nov 2012
    Location
    nigeria
    Posts
    844
    All that flowed from the miniscule universe was not planned.they were inevitable...all that will come from this current universe is also inevitable.
    "I am sorry for making this letter longer than usual.I actually lacked the time to make it shorter."###
    Reply With Quote  
     

  25. #24  
    Forum Ph.D. merumario's Avatar
    Join Date
    Nov 2012
    Location
    nigeria
    Posts
    844
    The question now is: does the odds not favour other life? Or even if does life ain't existing yet.the odd favours that there will exist a new form of life.
    "I am sorry for making this letter longer than usual.I actually lacked the time to make it shorter."###
    Reply With Quote  
     

  26. #25  
    Quagma SpeedFreek's Avatar
    Join Date
    Jan 2011
    Location
    London, UK
    Posts
    2,786
    I would find it highly unlikely that the conditions required for life to form would only occur here on Earth, considering that there are hundreds of billions of other stars in our galaxy (around 300,000,000,000 stars in the Milky Way) and hundreds of billions of other galaxies in our observable universe, and we don't know how much bigger the whole universe is than the part we can see.

    I would expect life to be pretty common in the universe, but the distances involved are so large that I am not so sure we will ever meet any!
    Reply With Quote  
     

  27. #26  
    Forum Ph.D. merumario's Avatar
    Join Date
    Nov 2012
    Location
    nigeria
    Posts
    844
    Yeah! Or if they will ever meet us...i feel sad to think that there could be life somewhere and we cannot reach out to them..sad!
    "I am sorry for making this letter longer than usual.I actually lacked the time to make it shorter."###
    Reply With Quote  
     

  28. #27  
    Universal Mind John Galt's Avatar
    Join Date
    Jul 2005
    Posts
    14,169
    While several of you have said you can't quite understand the answers, I confess I can't quite understand the question. After all, where is the Earth located? Here! Everthing else is there.
    Strange and dan hunter like this.
    Reply With Quote  
     

  29. #28  
    Forum Ph.D. merumario's Avatar
    Join Date
    Nov 2012
    Location
    nigeria
    Posts
    844
    Quote Originally Posted by John Galt View Post
    While several of you have said you can't quite understand the answers, I confess I can't quite understand the question. After all, where is the Earth located? Here! Everthing else is there.
    did you read the above posts? The location of the earth in the universe can only be related to other things..since theres no centre of the universe,no edge. You only can relate it to the nearest cosmic bodies.
    "I am sorry for making this letter longer than usual.I actually lacked the time to make it shorter."###
    Reply With Quote  
     

  30. #29  
    Forum Freshman
    Join Date
    Aug 2011
    Location
    East Anglia - England - Moving
    Posts
    80
    We are not even in a "proper" Arm of this Galaxy.
    We are in the Cygnus-Orion Minor Arm - a sort of branch off the Sagittarius Arm of this Galaxy.
    If I wasn't so stupid - I might know what I was doing
    Reply With Quote  
     

  31. #30  
    Universal Mind John Galt's Avatar
    Join Date
    Jul 2005
    Posts
    14,169
    Quote Originally Posted by merumario View Post
    Quote Originally Posted by John Galt View Post
    While several of you have said you can't quite understand the answers, I confess I can't quite understand the question. After all, where is the Earth located? Here! Everthing else is there.
    did you read the above posts? The location of the earth in the universe can only be related to other things..since theres no centre of the universe,no edge. You only can relate it to the nearest cosmic bodies.
    Did you hear of the use of whimsical humour to make a subtle, but important point?
    Reply With Quote  
     

  32. #31  
    Suspended
    Join Date
    Jan 2005
    Location
    Nashville
    Posts
    317
    Quote Originally Posted by pineapples View Post
    I’m told there is not one central point in the universe that actually expanded out. But rather every point in the universe expanded out and is still expanding. You are actually sitting where the universe first began to expand, as is everywhere else in the universe. I won’t lie to you, as I don’t get it myself

    But what I do know is that we’re now able to say I’m the centre of the universe without me sounding arrogant!
    This may be true even if it is hard to comprehend.
    Reply With Quote  
     

  33. #32  
    Forum Ph.D. merumario's Avatar
    Join Date
    Nov 2012
    Location
    nigeria
    Posts
    844
    Quote Originally Posted by John Galt View Post
    Quote Originally Posted by merumario View Post
    Quote Originally Posted by John Galt View Post
    While several of you have said you can't quite understand the answers, I confess I can't quite understand the question. After all, where is the Earth located? Here! Everthing else is there.
    did you read the above posts? The location of the earth in the universe can only be related to other things..since theres no centre of the universe,no edge. You only can relate it to the nearest cosmic bodies.
    Did you hear of the use of whimsical humour to make a subtle, but important point?
    repeating a question over and over again does not show being subtle,its insanity....asking same question over and over again,and you expecting different answer!ask again then you will see.
    "I am sorry for making this letter longer than usual.I actually lacked the time to make it shorter."###
    Reply With Quote  
     

  34. #33  
    Universal Mind John Galt's Avatar
    Join Date
    Jul 2005
    Posts
    14,169
    Quote Originally Posted by merumario View Post
    repeating a question over and over again does not show being subtle,its insanity....asking same question over and over again,and you expecting different answer!ask again then you will see.
    Which question did I ask over and over again.
    Reply With Quote  
     

  35. #34  
    Forum Ph.D. merumario's Avatar
    Join Date
    Nov 2012
    Location
    nigeria
    Posts
    844
    check post #27
    "I am sorry for making this letter longer than usual.I actually lacked the time to make it shorter."###
    Reply With Quote  
     

  36. #35  
    Universal Mind John Galt's Avatar
    Join Date
    Jul 2005
    Posts
    14,169
    I did not ask a question over and over again. I restated the opening question to establish that that was what I was about to answer. This is a useful technique when you wish to make your meaning clear. I am coming to wish that you would use similar techniques, since I rarely understand what the intent of your posts is.
    Halliday likes this.
    Reply With Quote  
     

  37. #36  
    Time Lord
    Join Date
    Mar 2007
    Posts
    8,046
    If I'm not mistaken, we can know our absolute velocity relative to the cloud of charged particles that caused the Cosmic Microwave Background Radiation. So even we can't determine our position relative to the rest of the universe, at least we know our velocity.


    Quote Originally Posted by Strange View Post
    Quote Originally Posted by pineapples View Post
    Let’s say I held a measuring tape on Earth and somebody else was holding the other end of that measuring tape on another planet, in another galaxy (far far away).

    Is it that those two galaxies are not actually traveling away from each other but Space itself is actually stretching/expanding? So the measuring tape never snaps in-half, but instead, stretches/expands along with Space.
    They are getting further apart because the distance between them is increasing; the space in between is getting "larger". The measuring tape will snap because it is made of "stuff" and is not able to stretch that much. Space is not made of stuff, it is just a measure of the distance between things.
    It always perplexes me how people can simultaneously believe that space itself is expanding, and that space itself is not a substance or object of some kind with dimensions.

    How does it expand if it doesn't have an original size? How does it carry matter with it as it goes, if it isn't interacting with that matter? How can it interact with matter if it itself is neither matter nor energy?

    (I might as well ask a Catholic how it's possible that God can be three and one. They'll probably just tell me that it's too complicated for a mortal mind to understand, and I should just accept it. )
    Some clocks are only right twice a day, but they are still right when they are right.
    Reply With Quote  
     

  38. #37  
    Quagma SpeedFreek's Avatar
    Join Date
    Jan 2011
    Location
    London, UK
    Posts
    2,786
    Quote Originally Posted by kojax View Post
    If I'm not mistaken, we can know our absolute velocity relative to the cloud of charged particles that caused the Cosmic Microwave Background Radiation. So even we can't determine our position relative to the rest of the universe, at least we know our velocity.
    You are not mistaken about our velocity relative to the local CMBR "rest frame". We are travelling at something around 600 km/s relative to it.

    Quote Originally Posted by kojax View Post
    It always perplexes me how people can simultaneously believe that space itself is expanding, and that space itself is not a substance or object of some kind with dimensions.

    How does it expand if it doesn't have an original size? How does it carry matter with it as it goes, if it isn't interacting with that matter? How can it interact with matter if it itself is neither matter nor energy?

    (I might as well ask a Catholic how it's possible that God can be three and one. They'll probably just tell me that it's too complicated for a mortal mind to understand, and I should just accept it. )
    Here is your answer.

    [0707.0380] Expanding Space: the Root of all Evil?

    Abstract:
    While it remains the staple of virtually all cosmological teaching, the concept of expanding space in explaining the increasing separation of galaxies has recently come under fire as a dangerous idea whose application leads to the development of confusion and the establishment of misconceptions. In this paper, we develop a notion of expanding space that is completely valid as a framework for the description of the evolution of the universe and whose application allows an intuitive understanding of the influence of universal expansion. We also demonstrate how arguments against the concept in general have failed thus far, as they imbue expanding space with physical properties not consistent with the expectations of general relativity.
    Basically, this paper explains how the "expansion of space" is an analogy that simply describes the increase in distance between highly separated objects using the full general relativistic treatment, and should in no way be taken to mean space itself is something with any tangible properties that expand. I will not tell you that it's too complicated for a mortal mind to understand, you just need to read through the paper to understand it.
    Reply With Quote  
     

  39. #38  
    Forum Ph.D. merumario's Avatar
    Join Date
    Nov 2012
    Location
    nigeria
    Posts
    844
    and it still won't become clear like crystal clear.
    "I am sorry for making this letter longer than usual.I actually lacked the time to make it shorter."###
    Reply With Quote  
     

  40. #39  
    Forum Freshman
    Join Date
    Feb 2014
    Location
    Oztralia
    Posts
    5
    you are the centre of your universe
    Reply With Quote  
     

  41. #40  
    Forum Cosmic Wizard
    Join Date
    Dec 2013
    Posts
    2,408
    The Big Bang is at the centre of the universe and we are located at the opposite end of the universe from it.
    This is from the idea of lightcones.

    We can only locate our position by relating ourselfs to the things we can observe.
    Other than that the idea of having a location is quite meaningless.
    We are on a planet obiting the star we call the Sun, which is on the arm of a galaxy called the Milky Way which is near...
    Reply With Quote  
     

  42. #41  
    Malignant Pimple shlunka's Avatar
    Join Date
    Jan 2013
    Location
    Dogbox in front of Dywyddyr's house.
    Posts
    1,784
    Down the hall, first door on the right.
    dan hunter likes this.
    "MODERATOR NOTE : We don't entertain trolls here, not even in the trash can. Banned." -Markus Hanke
    Reply With Quote  
     

  43. #42  
    Moderator Moderator
    Join Date
    Apr 2007
    Location
    Washington State
    Posts
    8,324
    Quote Originally Posted by dan hunter View Post
    The Big Bang is at the centre of the universe and we are located at the opposite end of the universe from it.
    Ah no. It's actually more accurate to say we are right where the big bang happened...dead center (as is every other place).
    dan hunter likes this.
    Meteorologist/Naturalist & Retired Soldier
    “The Holy Land is everywhere” Black Elk
    Reply With Quote  
     

  44. #43  
    Forum Cosmic Wizard
    Join Date
    Dec 2013
    Posts
    2,408
    Quote Originally Posted by Lynx_Fox View Post
    Quote Originally Posted by dan hunter View Post
    The Big Bang is at the centre of the universe and we are located at the opposite end of the universe from it.
    Ah no. It's actually more accurate to say we are right where the big bang happened...dead center (as is every other place).
    Not too bad, but the big bang was then and we are now.

    Paradox of Special Relativity

    I love these zombie threads.
    I should thank whoever it is that keeps raising them from the dead.
    Reply With Quote  
     

  45. #44  
    Time Lord
    Join Date
    Mar 2007
    Posts
    8,046
    The solution to the paradox is that one or the other of Cerulean or Vermilion is the emitter. (Light is emitted by physical objects.) If Cerulean is moving away from the emitter, then the light reaching him appears to be red shifted. The light traveling the other direction appears to be blue shifted (although he probably doesn't have any way to observe the light that's moving away). By noting the red and blue shift, Cerulean should be able to tell that he is in fact moving relative to the expanding light cone.
    Some clocks are only right twice a day, but they are still right when they are right.
    Reply With Quote  
     

  46. #45  
    Forum Cosmic Wizard
    Join Date
    Dec 2013
    Posts
    2,408
    Quote Originally Posted by kojax View Post
    The solution to the paradox is that one or the other of Cerulean or Vermilion is the emitter. (Light is emitted by physical objects.) If Cerulean is moving away from the emitter, then the light reaching him appears to be red shifted. The light traveling the other direction appears to be blue shifted (although he probably doesn't have any way to observe the light that's moving away). By noting the red and blue shift, Cerulean should be able to tell that he is in fact moving relative to the expanding light cone.
    Actually they are both in the center of the light cone and see their universes differently. In other words their realities are subjective instead of objective.
    I am not sure if I agree with that interpretation of it though because I find the idea that there is an objective reality that we all exist in a very hard one to abandon.

    However that was just a throw away remark that Lynx Fox was obsessing on.
    The part of my original post which Lynx didn't bother quoting was about how we can only locate things in relation to other things.
    Trying to name a location without referring to another location is just nonsense. Since we can not observe the edges of the universe there is no way to say where the center of it is.
    Reply With Quote  
     

  47. #46  
    Time Lord
    Join Date
    Mar 2007
    Posts
    8,046
    I think I need to be more clear. Light is always emitted by a physical object. So..... that physical object is, by definition, the only true center of the light cone. In most cases, the emitter is an electron.

    The center of a light cone is not a point in space. It's a physical object in space.

    Space itself has no velocity. It simply lacks that property. And without a velocity, it also can't have a location. Without a location, it can't serve as the center point for a light cone.
    Some clocks are only right twice a day, but they are still right when they are right.
    Reply With Quote  
     

  48. #47  
    Forum Cosmic Wizard
    Join Date
    Dec 2013
    Posts
    2,408
    Quote Originally Posted by kojax View Post
    I think I need to be more clear. Light is always emitted by a physical object. So..... that physical object is, by definition, the only true center of the light cone. In most cases, the emitter is an electron.

    The center of a light cone is not a point in space. It's a physical object in space.

    Space itself has no velocity. It simply lacks that property. And without a velocity, it also can't have a location. Without a location, it can't serve as the center point for a light cone.
    My comment on them seeing space differently is from the same source on the next page.
    Here is the quote
    "Einstein's solution to the paradox is that Cerulean's spacetime is skewed compared to Vermilion's.The thing to notice in the diagram is that Cerulean is in the centre of the lightcone, according to the way Cerulean perceives space and time.
    Vermilion remains at the centre of the lightcone according to the way Vermilion perceives space and time."

    Anyhow.
    I agree with you that space itself has no location. Locations are given from other locations. If we have no other reference points the default refence point is ourself. That is trivially obvious.

    However I am not sure about your interpretation of what a light cone is.

    A simple web page from John D. Norton, Department of History and Philosophy of Science, University of Pittsburgh
    http://www.pitt.edu/~jdnorton/teachi...acetime/#Right

    Quote
    To have a light cone, we do not need light to be present. The cones map out the trajectories light would take if light were to be present. Since it is just the possibilities that are mapped out, not necessarily the trajectories of actual light. Spacetime still has a light cone structure in the dark! Unquote

    His position is that any event or location we select is the geometrical origin of a lightcone.
    Last edited by dan hunter; February 16th, 2014 at 04:03 PM. Reason: fix link
    John Galt likes this.
    Reply With Quote  
     

  49. #48  
    Forum Bachelors Degree GoldenRatio's Avatar
    Join Date
    Dec 2013
    Posts
    415
    If the earth(crust) was the universe, where would the center be? the equator? the poles?

    Consider the universe the same way.
    Reply With Quote  
     

  50. #49  
    Forum Cosmic Wizard
    Join Date
    Dec 2013
    Posts
    2,408
    Quote Originally Posted by GoldenRatio View Post
    If the earth(crust) was the universe, where would the center be? the equator? the poles?

    Consider the universe the same way.
    Or you could think of it as being on a small island in the middle of a great empty ocean with no idea if there is any other land besides the few small islands you can see but which are too far away to swim to...

    I guess this thread shows that asking where the center of the universe is located is not a very useful question.
    Reply With Quote  
     

  51. #50  
    Anti-Crank AlexG's Avatar
    Join Date
    Mar 2012
    Posts
    2,810
    The Big Bang is at the centre of the universe and we are located at the opposite end of the universe from it.
    There is no center of the universe. and there is no opposite end of the universe. Since everything is expanding away from every other point (non-gravitationally bound) every point can be considered to the be center.
    Its the way nature is!
    If you dont like it, go somewhere else....
    To another universe, where the rules are simpler
    Philosophically more pleasing, more psychologically easy
    Prof Richard Feynman (1979) .....

    Das ist nicht nur nicht richtig, es ist nicht einmal falsch!"
    Reply With Quote  
     

Similar Threads

  1. Black Hole Location in Universe
    By MOHANTHILAGARAJ in forum Physics
    Replies: 3
    Last Post: December 15th, 2011, 07:10 AM
  2. The Universe, is it Alive? How About Earth?
    By theocid in forum Personal Theories & Alternative Ideas
    Replies: 0
    Last Post: May 18th, 2010, 06:26 PM
  3. Earth in the Phoenix Universe
    By prometheus66 in forum Astronomy & Cosmology
    Replies: 4
    Last Post: July 19th, 2009, 05:04 PM
  4. Earth the center of Universe?
    By thyristor in forum Astronomy & Cosmology
    Replies: 35
    Last Post: June 4th, 2008, 08:29 PM
Tags for this Thread

View Tag Cloud

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •