1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How would we measure time and location in space?

  1. Sep 23, 2013 #1
    Let us all pretend it 150 years in the future and we all have spaceships and can travel through space easily without disrupting time.

    Our only measure of location would be compared to Earth, and our measure of time would be earth time (revolutions around the sun and rotations). What if we come across some friendly aliens and we want to communicate with them. There home planet would have a longer or shorter year and they would not compare there location to our earth. So we and all our alien friends would need a constant location that would never move. I think the center of the universe (place of the big bang) would be a good place. However if we were going to make a 3D plane with the origin at the center of the universe, we would need 3 noncollinear points to mark such plane. We would need a unit of time also. I think we could use a hydrogen atom. We could multiply the diameter by a few billion, and we have an extremely precise measurement of distance. We would also need a constant in time. but we would need two points to mark a line. The first point would probably be the origin of the universe in time (the time of the big bang). The other point could be a unit of time. We could say it is 4 billion or so years from the beginning of space, however our alien friends have a different year than us. So we need another constant in time. I think we would use the speed of light and a distance to do this. Light will always take the same amount of time to go X distance, therefore we need a constant distance. Again we could use a hydrogen atom(multiplied by a few billion of course) and see how long it takes light to go that far, and multiply that by a hundred or so, and then we have constant unit of time to compare to the beginning of the universe.

    So, can you come up with anything better for a unit of time or distance? Also we still need two more points noncollinear points compared to the center of the universe.

    P.S. Thank you for reading that if you did. : )
  2. jcsd
  3. Sep 23, 2013 #2


    Staff: Mentor

  4. Sep 23, 2013 #3
    Note that the Big bang didn't happen in one place. It happened everywhere
  5. Sep 24, 2013 #4
    The big bang happend everyware

    Yes, but didn't it start in one place?
  6. Sep 24, 2013 #5


    User Avatar
    Gold Member

    Emphatically not. You need to study some basic cosmology.

    I recommend the link in my signature as a place to start.
  7. Mar 3, 2015 #6
    Your question indicates some misunderstandings of space and time. They are not independent of each other. As phinds says, you need to study more cosmology, or at least some basic relativity. Before the Big Bang, there was no place, or time.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook