Notices
Results 1 to 7 of 7
Like Tree1Likes
  • 1 Post By MagiMaster

Thread: Comparing our occupation of the known universe to a planetary scale.

  1. #1 Comparing our occupation of the known universe to a planetary scale. 
    New Member
    Join Date
    Mar 2014
    Posts
    2
    Hello. I thought this might do better here, as it's a maths question. If I were to scale down the size of the known universe to the size of our planet, would anyone know how much of the planet we would occupied on this scale? I'm assuming it's a very small space. Perhaps a better comparison might be to our galaxy. How much of a galaxy would we occupy, if that galaxy were shrunk to planetary size? I hope this question makes sense, and I just think it's an interesting comparison.


    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Masters Degree
    Join Date
    Jan 2011
    Posts
    739
    Use our galaxy, not the known universe. There's a pretty reliable number for the size of our galaxy.

    The Milky Way galaxy is approx 100,000 ly in diameter and I'm not sure how thick it is, but you can find these values in wiki and other places. Now, the core of the galaxy, like most spirals, is thicker than the outward arms. Also, the globular clusters extend the center "sphere"/core of the galaxy even further. Make an estimate for the average thickness (which will be the hardest part of this calculation) and then use the formula for finding the volume of a cylinder (given diameter and height) to compute the total volume of of our galaxy. Since we only occupy the planet Earth, determine the volume of the Earth, ignoring the fact that we only live on the surface. Divide the volume of the Earth by the volume of the galaxy and you have your ratio. Given this ration you can easily use it to find what how much of the planet we would occupy on this scale.

    I'm not going to look up the values or do the math. That's for you to do. The math is very simple.

    NOTE: The cylinder shape that I'm talking about is a "flat" cylinder -- one where the width (diameter) is several times more than its height.


    Last edited by PumaMan; March 7th, 2014 at 01:16 PM.
    Reply With Quote  
     

  4. #3  
    Forum Masters Degree
    Join Date
    Jan 2011
    Posts
    739
    If you do an internet search for "images of Milky Way galaxy" you'll find thousands of pictures of what scientists think that our galaxy would look like from the outside.

    Post your results when you're done so the members can verify your calculations.
    Reply With Quote  
     

  5. #4  
    Forum Masters Degree
    Join Date
    Jan 2011
    Posts
    739
    Before you start you may want to wait a while to see if forum members have any better suggestions than mine or corrections to what I posted.
    Reply With Quote  
     

  6. #5  
    Suspended
    Join Date
    Apr 2007
    Location
    Pennsylvania
    Posts
    8,795
    The diameter of the Milky Way is about 100,000 light years, which is about 9.46E20 meters. The diameter of the earth is about 12.74E6 meters. So that is a ratio of 7.4E13 to 1. So if you divide 12.74E6 meters by 7.4E13 you get 1.72E-7 meters. That's about the size of viruses.
    Reply With Quote  
     

  7. #6  
    New Member
    Join Date
    Mar 2014
    Posts
    2
    Thanks Harold, I had done similar math in relation to diameter. I was hoping the scale would be something familiar, like a pin head, but ended up going from a distance so vastly expansive it's difficult to imagine, to a scale so minute, it's difficult to imagine. Maybe there's a revelation in that.
    Reply With Quote  
     

  8. #7  
    Forum Radioactive Isotope MagiMaster's Avatar
    Join Date
    Jul 2006
    Posts
    3,440
    I think the point is:

    Quote Originally Posted by Douglas Adams
    Space... is big. Really big. You just won't believe how vastly hugely mindbogglingly big it is...
    Daecon likes this.
    Reply With Quote  
     

Similar Threads

  1. The Scale of the Universe 2
    By Cogito Ergo Sum in forum Links
    Replies: 6
    Last Post: February 8th, 2014, 11:07 AM
  2. The scale of the universe!
    By msafwan in forum Physics
    Replies: 8
    Last Post: August 2nd, 2012, 05:27 PM
  3. Comparing a wheal and a blister
    By Donnar in forum Biology
    Replies: 3
    Last Post: July 3rd, 2012, 07:03 PM
  4. Comparing science across cultures?
    By miwashi in forum General Discussion
    Replies: 0
    Last Post: August 7th, 2011, 10:06 PM
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
  •