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  • Dec 9, 2011, 03:25 AM
    kingkit
    Big Bang vs Speed of Light
    I am 65 without any formal knowledge in physics or astrophysics but am fascinated by the subject. There is one thing that puzzles my and I cannot get it out of my head. In The Big Bang the universe went from zero to full size in a fraction of a second yet the laws of physics state that nothing travels faster than light. My logic tells me that the universe could only have expanded to 186,000 miles in the 1st second. Can you tell me if I have got it right?
    Kind regards
    Chris Ryan
  • Dec 9, 2011, 03:58 AM
    joypulv
    Supposedly the expansion of the universe is not constrained by the speed limit of light, which is defined by objects moving relative to each other. I don't understand expansion very well either, but since the arguments are ongoing among physicists, that's OK.
  • Dec 9, 2011, 08:08 AM
    ebaines
    kingkit: the universe did not go to "full size" in a fraction of a second. In that first second it expanded from zero to about 186,000 miles in radius, as you suggest. Think of a grenade exploding - the shrapnel expands away from the center at essentially a constant speed. So too with the universe. And it's still expanding. The radius of our universe is essentially 186,000 miles per second times the age of the universe (about 13.8 billion years) which works out to mean the furthest objects we could ever see are 13.8 billiion light years away. And every year that distance grows by another light year.
  • Dec 9, 2011, 01:40 PM
    TUT317
    Quote:

    Originally Posted by ebaines View Post
    kingkit: the universe did not go to "full size" in a fraction of a second. In that first second it expanded from zero to about 186,000 miles in radius, as you suggest. Think of a grenade exploding - the shrapnel expands away from the center at essentially a constant speed. So too with the universe. And it's still expanding. The radius of our universe is essentially 186,000 miles per second times the age of the universe (about 13.8 billion years) which works out to mean the furthest objects we could ever see are 13.8 billiion light years away. And every year that distance grows by another light year.


    Hi ebaines,

    Perhaps kingkit is thinking of the inflationary period of the Big Bang.


    Tut
  • Dec 18, 2011, 05:55 AM
    rupertpupkin123
    Like someone already said, it did not immediately go to full size. It expanded extremely fast though. In the matter of a few seconds it was already mind blowingly large. I saw a documentary on this once.
  • Aug 10, 2013, 05:25 PM
    rbawjaws
    Answer with a question it has been found recently that the universe is not expanding at a uniform rate but is actually accelerating so where does that put your 1860000mles per sec expansion
  • Aug 11, 2013, 08:42 PM
    Tuttyd
    Quote:

    Originally Posted by rbawjaws View Post
    answer with a question it has been found recently that the universe is not expanding at a uniform rate but is actually accelerating so where does that put your 1860000mles per sec expansion

    Yes, I believe it was an Australian physicist Brian Schmidt who proved that the universe is accelerating and an ever increasing rate. In fact it seems as though it is expanding faster than the speed of light.

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