Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Infinitely old earth?

  1. Sep 8, 2010 #1
    Hi guys! It's my first time posting here. I have great interests in physics and im only a cambridge "A" level physics student (the physics here is really nonsense =.=) Ok I will start on my post. The big bang theory states that time 'began' 10-15 billion years ago. I am not sure how to put my thinking across to you guys, but I will try to explain how i think here... The possible beginning of time happened years ago. Since time is relative, am I safe to say it happened somewhere between zero to 100000000000000000000000000000000billion years ago? Or did time start infinitely long ago? Or time did not start (it didnt stop in the first place). Putting in layman's term, If a million years may seem short to the formation of a planet, is 1000000000000000000000000billion years nothing compared to the beginning of time? This is my first time telling anyone about this thought. Sorry if it seems noob =[

    PS: I really suck at putting out my thought, and my understanding of relativity(I never learnt that in school =[ ) but I hope u guys can understand my 'weird' thinking.
    Thanks! :D
  2. jcsd
  3. Sep 8, 2010 #2
    Oh no... I wrote the title wrongly. It is supposed to be "Infinitely old universe". Sorry for the mistake! :D
  4. Sep 8, 2010 #3

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2017 Award

    How do we know that Christmas happened 8-1/2 months ago? Since time is relative, why din't we say it happened a billion years ago or five minutes ago?
  5. Sep 8, 2010 #4
    we had a calander last christmas. did we have one when time began
  6. Sep 8, 2010 #5
    ok im trying to state the fact that the time difference between last christmas and now is relative but has an absolute ratio to the tick of the clock. The difference between the 'beginning' of time and now is relative.
  7. Sep 8, 2010 #6

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2017 Award

    What makes you think this is a "fact"?
  8. Sep 8, 2010 #7
    If you look at the clock that was around from the big bang, it would show ~13.7 billion years.
  9. Sep 8, 2010 #8


    User Avatar
    Science Advisor
    Gold Member

    The universe may well be infinitely ancient. The one we see [the observable universe] is not, by all current evidence [WMAP, redshift, etc.]. According to clocks on earth, this universe is about 13.7 billion years of age. If you looked through a gargantuan telescope at a clock in a distant galaxy, it would indicate the universe is younger than 13.7 billion years [a finite speed of light thing].
  10. Sep 8, 2010 #9
    No it doesn't.

    1) Time isn't relative

    2) You are safe to say that the big bang happened 243234234 zardaks, 677567 kabobs, or 34124981230481239034324 stylons, where zardaks, kabobs, and stylons are time units that you define.
  11. Sep 9, 2010 #10


    User Avatar
    Science Advisor

    Well, you basically do it in two steps. First, you have to make a standard clock. Today our standard clock is a Cesium atom. Specifically, one second is:
    Thus time, as we see it, is intimately connected to atomic physics. As long as atomic physics remains the same, the above clock will work. Once we define time in this manner, we can talk about the proper time of an observer that is stationary with respect to the CMB and not near any strong gravitational wells (e.g. black holes). That time is unambiguous at about 13.7 billion years. Other observers which move with respect to the CMB or exist in a strong gravitational potential well will see a smaller time.
  12. Sep 12, 2010 #11
    To me, infinitely big and infinitely old mean the same
    thing....it has always been everywhere....it was not born
    and will not die.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook