Page 1 of 3 123 LastLast
Results 1 to 10 of 26
  1. #1
    chas53's Avatar
    chas53 is offline SUPER GIANT
    Points: 58,017, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    Got three Friends20+ Friends Achievement!200+ Posts Achievement!First 1000 Experience Points365 Days+ Registered Achievement!
    Join Date
    Apr 2011
    Location
    New York
    Posts
    1,053
    Points
    58,017
    Level
    100
    Thanks
    20,851
    Thanked 1,500x 563 Posts

    Default Universe size at the Big Bang



    would someone please tell me what the current Big Bang theory is about the size of the Universe when the Big Bang banged??

    I think I have read a couple of different answers to the question.

    was it a few millimeters across??

    is there no consensus??

    is it impossible to come up with a really good hypothesis as to the nature of the Universe that early in its history???

    also, due to the nature of relativity and the need to describe one's reference points when constructing scenarios, if a galaxy is red shifting and moving farther away from us (because of the expansion of space), from that galaxy's perspective, aren't we doing the same thing???? (also of course the larger the distance, the faster our galaxy and the other one are moving away from each other.)

    also, am I the only one here who continues to have a hard time understanding how the Universe could have started from a single small point, a very small area, and has been expanding ever since, but yet there's no center from which it expanded???
    I think this has been explained before, but would someone please be kind and refresh my memory as to how this is possible?????
    I know that I have learned that we are as much at the center of the Universe as anything else. ah, whatever. any help greatly appreciated as always.
    peace,
    Chasman

  2. The Following User Says Thank You to chas53 For This Useful Post:

    astroval (07-18-2011)

  3. #2
    DanielC's Avatar
    DanielC is offline SUPER GIANT
    Points: 6,189, Level: 54
    Level completed: 20%, Points required for next Level: 161
    Overall activity: 0%
    Achievements:
    Ghost Achievement! Averaging 5+ posts a day!200+ Posts Achievement!Got three Friends400+ Posts Achievement5 Threads Achievement!
    Join Date
    Jun 2011
    Location
    Sweden, Earth
    Posts
    852
    Points
    6,189
    Level
    54
    Thanks
    121
    Thanked 1,152x 636 Posts

    Default

    Quote Originally Posted by chas53 View Post
    would someone please tell me what the current Big Bang theory is about the size of the Universe when the Big Bang banged??

    I think I have read a couple of different answers to the question.

    was it a few millimeters across??

    is there no consensus??
    We do not know what was happening at exactly "t = 0" because for that we need a theory of quantum gravity and we don't have one. We know what was happening only up to a tiny fraction of a second after the Big Bang, at a time when the universe was very tiny. I don't know how tiny, I forget. I think it was something absurdly small like "size of an atom" but I really can't remember and I couldn't find a reference.

    There is a nice page about this on Wikipedia:

    Timeline of the Big Bang - Wikipedia, the free encyclopedia



    is it impossible to come up with a really good hypothesis as to the nature of the Universe that early in its history???
    For t = 0, not at all. Looking at the timeline I just linked, from approximately the Hadron epoch onward (or about 10^-6 seconds after the BB) we have a pretty good idea of what happens. But as you move further back in time from there, things gradually become more speculative, and by the time you get to the earliest epoch, the "Planck" epoch, we basically have no idea.

    Whether we have a good idea of what happens or not depends on how good our physical theories are at that scale. Like whether we have a lot of experimental evidence to understand the underlying physics. For example, we have tons of experimental evidence on how Hadrons (e.g. protons) behave. The epoch before that is the Quark epoch. We understand Quarks reasonably well, but less well than Hadrons. And when you move to supersymetry or inflation epochs, these have a good deal of speculation.

    But imagine that one day we discover supersymmetry in the lab an can build machines to explore it an study it and see how matter behaves at that scale, then we would have a better idea of what the universe was like at the supersymmetry epoch. Does that make sense?

    also, due to the nature of relativity and the need to describe one's reference points when constructing scenarios, if a galaxy is red shifting and moving farther away from us (because of the expansion of space), from that galaxy's perspective, aren't we doing the same thing????
    Yes. An observer in another galaxy will see us moving away from her.

    also, am I the only one here who continues to have a hard time understanding how the Universe could have started from a single small point, a very small area, and has been expanding ever since, but yet there's no center from which it expanded???
    The origin of the universe, an the inflation epoch are currently a mystery. The part about there being no center doesn't bother me much. The surface of the Earth has no centre either.
    Astronomer. Lund Observatory

    Current project: Formation of terrestrial planets.
    Previous project: Dark matter capture in binary stars.
    Previous project: Observational history of planetary systems.
    Previous project: Contributions to the GNU Fortran Compiler.

  4. The Following 5 Users Say Thank You to DanielC For This Useful Post:

    chas53 (07-10-2011),fogfire (07-11-2011),j.gardavsky (07-10-2011),Joe Lalumia (07-10-2011),kwalker (07-10-2011)

  5. #3
    Space Jockey's Avatar
    Space Jockey is offline Bright Giants
    Points: 3,310, Level: 37
    Level completed: 74%, Points required for next Level: 40
    Overall activity: 0%
    Achievements:
    200+ Posts Achievement!Got three Friends20+ Friends Achievement!400+ Posts AchievementFirst 1000 Experience Points
    Join Date
    Mar 2011
    Location
    deactivated user
    Posts
    462
    Points
    3,310
    Level
    37
    Thanks
    205
    Thanked 233x 165 Posts

    Default

    A general idea taught lately is that is was the size of the smallest component of an atom, So it sounds similar to what you have heard.

  6. #4
    chas53's Avatar
    chas53 is offline SUPER GIANT
    Points: 58,017, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    Got three Friends20+ Friends Achievement!200+ Posts Achievement!First 1000 Experience Points365 Days+ Registered Achievement!
    Join Date
    Apr 2011
    Location
    New York
    Posts
    1,053
    Points
    58,017
    Level
    100
    Thanks
    20,851
    Thanked 1,500x 563 Posts

    Default

    thank you for your detailed awesome excellent reply.

    I will read the wikipedia article.

    your post has answered much of what I asked. and made many things much clearer.

    if you are so inclined I would welcome any other thoughts regarding your last
    2 sentences. I am struggling to understand what you mean with your analogy that the earth's surface has no center either.


    Quote Originally Posted by DanielC View Post
    We do not know what was happening at exactly "t = 0" because for that we need a theory of quantum gravity and we don't have one. We know what was happening only up to a tiny fraction of a second after the Big Bang, at a time when the universe was very tiny. I don't know how tiny, I forget. I think it was something absurdly small like "size of an atom" but I really can't remember and I couldn't find a reference.

    There is a nice page about this on Wikipedia:

    Timeline of the Big Bang - Wikipedia, the free encyclopedia





    For t = 0, not at all. Looking at the timeline I just linked, from approximately the Hadron epoch onward (or about 10^-6 seconds after the BB) we have a pretty good idea of what happens. But as you move further back in time from there, things gradually become more speculative, and by the time you get to the earliest epoch, the "Planck" epoch, we basically have no idea.

    Whether we have a good idea of what happens or not depends on how good our physical theories are at that scale. Like whether we have a lot of experimental evidence to understand the underlying physics. For example, we have tons of experimental evidence on how Hadrons (e.g. protons) behave. The epoch before that is the Quark epoch. We understand Quarks reasonably well, but less well than Hadrons. And when you move to supersymetry or inflation epochs, these have a good deal of speculation.

    But imagine that one day we discover supersymmetry in the lab an can build machines to explore it an study it and see how matter behaves at that scale, then we would have a better idea of what the universe was like at the supersymmetry epoch. Does that make sense?



    Yes. An observer in another galaxy will see us moving away from her.



    The origin of the universe, an the inflation epoch are currently a mystery. The part about there being no center doesn't bother me much. The surface of the Earth has no centre either.

  7. #5
    Space Jockey's Avatar
    Space Jockey is offline Bright Giants
    Points: 3,310, Level: 37
    Level completed: 74%, Points required for next Level: 40
    Overall activity: 0%
    Achievements:
    200+ Posts Achievement!Got three Friends20+ Friends Achievement!400+ Posts AchievementFirst 1000 Experience Points
    Join Date
    Mar 2011
    Location
    deactivated user
    Posts
    462
    Points
    3,310
    Level
    37
    Thanks
    205
    Thanked 233x 165 Posts

    Default

    Quote Originally Posted by chas53 View Post
    thank you for your detailed awesome excellent reply.

    I will read the wikipedia article.

    your post has answered much of what I asked. and made many things much clearer.

    if you are so inclined I would welcome any other thoughts regarding your last
    2 sentences. I am struggling to understand what you mean with your analogy that the earth's surface has no center either.
    Imagine the surface area of a smooth globe and trying to determine what point denotes the center. make more sense?

  8. The Following User Says Thank You to Space Jockey For This Useful Post:

    chas53 (07-10-2011)

  9. #6
    KathyNS's Avatar
    KathyNS is offline Super Moderator
    Points: 173,014, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 69.0%
    Achievements:
    200+ Posts Achievement!Ghost Achievement! Averaging 5+ posts a day!First 1000 Experience Points400+ Posts AchievementGot three Friends
    Awards:
    Reply Award
    Join Date
    Nov 2010
    Location
    Nova Scotia
    Posts
    25,171
    Points
    173,014
    Level
    100
    Thanks
    6,659
    Thanked 14,984x 9,542 Posts
    Blog Entries
    3

    Default

    Quote Originally Posted by chas53 View Post
    I am struggling to understand what you mean with your analogy that the earth's surface has no center either.
    Try asking the question: where is the centre of the Earth's surface? Not the centre of the Earth. The centre of the surface. What is its latitude and longitude?

    If you think about it, you will realize that it doesn't have one.

    The universe is the same way.

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.


    DSO AP:
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,LRGB filters; KWIQ/QHY5 guide
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    ; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome;
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    (pier);
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    .

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.

  10. The Following User Says Thank You to KathyNS For This Useful Post:

    chas53 (07-10-2011)

  11. #7
    chas53's Avatar
    chas53 is offline SUPER GIANT
    Points: 58,017, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    Got three Friends20+ Friends Achievement!200+ Posts Achievement!First 1000 Experience Points365 Days+ Registered Achievement!
    Join Date
    Apr 2011
    Location
    New York
    Posts
    1,053
    Points
    58,017
    Level
    100
    Thanks
    20,851
    Thanked 1,500x 563 Posts

    Default

    thank you for helping me to understand.
    I am really trying to understand.

    here goes:

    the Earth is a ball. do you mean that the Universe is a ball????????

    the surface of the Earth is not a ball. the surface of the Earth is a sphere.
    a spherical surface. a spherical surface is not a ball. its a spherical surface.

    would you possibly be able to provide any more details that would help me in my efforts to better understand this???? I'm maybe getting closer. I am just not there yet.
    thanks,
    Charlie

    Quote Originally Posted by Space Jockey View Post
    Imagine the surface area of a smooth globe and trying to determine what point denotes the center. make more sense?
    Quote Originally Posted by KeithBC View Post
    Try asking the question: where is the centre of the Earth's surface? Not the centre of the Earth. The centre of the surface. What is its latitude and longitude?

    If you think about it, you will realize that it doesn't have one.

    The universe is the same way.

  12. #8
    KathyNS's Avatar
    KathyNS is offline Super Moderator
    Points: 173,014, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 69.0%
    Achievements:
    200+ Posts Achievement!Ghost Achievement! Averaging 5+ posts a day!First 1000 Experience Points400+ Posts AchievementGot three Friends
    Awards:
    Reply Award
    Join Date
    Nov 2010
    Location
    Nova Scotia
    Posts
    25,171
    Points
    173,014
    Level
    100
    Thanks
    6,659
    Thanked 14,984x 9,542 Posts
    Blog Entries
    3

    Default

    Quote Originally Posted by chas53 View Post
    the Earth is a ball. do you mean that the Universe is a ball????????
    The surface of the Earth example is only an example to help show that a geometric shapes does not have to have a centre. It does not mean that the universe is that shape. For one thing, the example is of a two-domensional surface, whereas the universe is at least three-dimensional.
    the surface of the Earth is not a ball. the surface of the Earth is a sphere.
    a spherical surface. a spherical surface is not a ball. its a spherical surface.
    I don't understand what you are trying to say here.

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.


    DSO AP:
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,LRGB filters; KWIQ/QHY5 guide
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    ; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome;
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    (pier);
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    .

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.

  13. The Following 2 Users Say Thank You to KathyNS For This Useful Post:

    chas53 (07-10-2011),DanielC (07-10-2011)

  14. #9
    DanielC's Avatar
    DanielC is offline SUPER GIANT
    Points: 6,189, Level: 54
    Level completed: 20%, Points required for next Level: 161
    Overall activity: 0%
    Achievements:
    Ghost Achievement! Averaging 5+ posts a day!200+ Posts Achievement!Got three Friends400+ Posts Achievement5 Threads Achievement!
    Join Date
    Jun 2011
    Location
    Sweden, Earth
    Posts
    852
    Points
    6,189
    Level
    54
    Thanks
    121
    Thanked 1,152x 636 Posts

    Default

    Quote Originally Posted by chas53 View Post
    thank you for helping me to understand.
    I am really trying to understand.

    here goes:

    the Earth is a ball. do you mean that the Universe is a ball????????

    the surface of the Earth is not a ball. the surface of the Earth is a sphere.
    a spherical surface. a spherical surface is not a ball. its a spherical surface.

    would you possibly be able to provide any more details that would help me in my efforts to better understand this???? I'm maybe getting closer. I am just not there yet.
    I don't know what distinction you are drawing between a ball and a sphere, but you are getting too worked up by details. I don't know what shape the universe has, but there are a lot of shapes that don't have a centre.

    If you don't like the Earth, then imagine a balloon. You and I are little ants crawling on the balloon. The balloon is inflating so you and I see far-away ants moving away from us. You and I set out on a quest to find the centre of the balloon. We take with us our two-dimensional crayons so we can mark the letter "X" on the centre of the baloon. We crawl and crawl everywhere and we never find the centre because a baloon doesn't have a centre, it is a closed surface without a border.

    Let's look at other examples:

    1) A rubber band. Where is the centre? Can you grab a marker and draw the point on the rubber band that mark an "X" on the centre.

    2) Grab a 20-inch pipe, grab a marker and try to put an "X" on the centre.

    3) Buy a donought and try put find the centre.

    You see, I am not saying that the universe has the shape of a balloon, a rubber band, a pipe and a donought. These are just examples of shapes that don't have a centre. I don't know what the shape of the universe is. We can't even see the entire universe and we are not even certain if the universe is flat, or has positive or negative curvature. Who knows, maybe the universe looks like a big donought :-)

    Hope that helps.
    Astronomer. Lund Observatory

    Current project: Formation of terrestrial planets.
    Previous project: Dark matter capture in binary stars.
    Previous project: Observational history of planetary systems.
    Previous project: Contributions to the GNU Fortran Compiler.

  15. The Following User Says Thank You to DanielC For This Useful Post:

    chas53 (07-10-2011)

  16. #10
    chas53's Avatar
    chas53 is offline SUPER GIANT
    Points: 58,017, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    Got three Friends20+ Friends Achievement!200+ Posts Achievement!First 1000 Experience Points365 Days+ Registered Achievement!
    Join Date
    Apr 2011
    Location
    New York
    Posts
    1,053
    Points
    58,017
    Level
    100
    Thanks
    20,851
    Thanked 1,500x 563 Posts

    Default

    thank you very much.

    what I do not understand is how something can expand from very small to very large and not have a center.

    I am trying. I just do not understand this.

    you guys do.

    maybe I am asking the question the wrong way.

    I would think that there is something simple here that I am missing.

    balls have centers. so do planets (like the Earth).
    balloons have centers.

    at least I thought they did. the center is inside the ball, the balloon, the planet.

    so the analogy that you are making is of a ball, a balloon, a planet that does not have an interior.

    so its an analogy. but I keep coming back to thinking that if something start out being very small and then expands to become very large, it has a center.

    I am not trying to be obtuse. I am honored that you guys reply to me. and I tell everyone that will listen to me about how awesome and brilliant you guys are.

    any more thoughts about what I'm missing welcome.

    Charlie



    Quote Originally Posted by KeithBC View Post
    The surface of the Earth example is only an example to help show that a geometric shapes does not have to have a centre. It does not mean that the universe is that shape. For one thing, the example is of a two-domensional surface, whereas the universe is at least three-dimensional.

    I don't understand what you are trying to say here.
    Quote Originally Posted by DanielC View Post
    I don't know what distinction you are drawing between a ball and a sphere, but you are getting too worked up by details. I don't know what shape the universe has, but there are a lot of shapes that don't have a centre.

    If you don't like the Earth, then imagine a balloon. You and I are little ants crawling on the balloon. The balloon is inflating so you and I see far-away ants moving away from us. You and I set out on a quest to find the centre of the balloon. We take with us our two-dimensional crayons so we can mark the letter "X" on the centre of the baloon. We crawl and crawl everywhere and we never find the centre because a baloon doesn't have a centre, it is a closed surface without a border.

    Let's look at other examples:

    1) A rubber band. Where is the centre? Can you grab a marker and draw the point on the rubber band that mark an "X" on the centre.

    2) Grab a 20-inch pipe, grab a marker and try to put an "X" on the centre.

    3) Buy a donought and try put find the centre.

    You see, I am not saying that the universe has the shape of a balloon, a rubber band, a pipe and a donought. These are just examples of shapes that don't have a centre. I don't know what the shape of the universe is. We can't even see the entire universe and we are not even certain if the universe is flat, or has positive or negative curvature. Who knows, maybe the universe looks like a big donought :-)

    Hope that helps.

 

 
Page 1 of 3 123 LastLast

Similar Threads

  1. What was the size of the universe before the big bang?
    By Indian Princess in forum Astrophysics Forum
    Replies: 0
    Last Post: 04-06-2008, 08:30 AM
  2. The Age and Size of the Universe.
    By George Dingwall in forum UK Astronomy Forum
    Replies: 11
    Last Post: 11-08-2007, 10:04 AM
  3. Size of the universe
    By Ray Vingnutte in forum General Astronomy Forum
    Replies: 2
    Last Post: 12-02-2004, 09:51 AM
  4. Size of Universe
    By Mike Williams in forum UK Astronomy Forum
    Replies: 0
    Last Post: 07-09-2004, 04:43 AM
  5. Size of the universe vs. c
    By timbo in forum General Astronomy Forum
    Replies: 5
    Last Post: 05-31-2004, 01:22 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Powered by vBulletin® Version 4.2.0
Powered by vBulletin®
All times are GMT. The time now is 07:00 AM.