Possibly stupid universe question
Discussion
I just read that the universe is about 13.7 billion years old and that the universe has a diameter of approx 90 billion light years.
My understanding is that things can't exceed the speed of light so if it all started with a Big Bang then even if everything expanded at the speed of light the diameter can only be 27.4 light years across unless at the point of the Big Bang the universe was already a considerable size.
So clever people help me out with this one, preferably with an explanation that does not need a physics degree to understand it
My understanding is that things can't exceed the speed of light so if it all started with a Big Bang then even if everything expanded at the speed of light the diameter can only be 27.4 light years across unless at the point of the Big Bang the universe was already a considerable size.
So clever people help me out with this one, preferably with an explanation that does not need a physics degree to understand it
Apologies for posting links, but these may be of use
https://en.wikipedia.org/wiki/Observable_universe#...
http://www.astro.ucla.edu/~wright/Dltt_is_Dumb.htm...
Essentially it doesn't really make sense to measure distances in light-years, the example the second link gives is
If an SR-71 blackbird flies over at Mach 3 and you hear the sound 30 seconds later, then answer to the question "How far away is it?" is clearly not 30 "sound seconds" or 10 km
https://en.wikipedia.org/wiki/Observable_universe#...
http://www.astro.ucla.edu/~wright/Dltt_is_Dumb.htm...
Essentially it doesn't really make sense to measure distances in light-years, the example the second link gives is
If an SR-71 blackbird flies over at Mach 3 and you hear the sound 30 seconds later, then answer to the question "How far away is it?" is clearly not 30 "sound seconds" or 10 km
RB Will said:
I just read that the universe is about 13.7 billion years old and that the universe has a diameter of approx 90 billion light years.
My understanding is that things can't exceed the speed of light so if it all started with a Big Bang then even if everything expanded at the speed of light the diameter can only be 27.4 light years across unless at the point of the Big Bang the universe was already a considerable size.
So clever people help me out with this one, preferably with an explanation that does not need a physics degree to understand it
The universe itself expanded 'faster than light speed'.My understanding is that things can't exceed the speed of light so if it all started with a Big Bang then even if everything expanded at the speed of light the diameter can only be 27.4 light years across unless at the point of the Big Bang the universe was already a considerable size.
So clever people help me out with this one, preferably with an explanation that does not need a physics degree to understand it
Getragdogleg said:
Eric Mc said:
TwigtheWonderkid said:
What is the universe expanding into?
Not a relevant question.It does not need to expand "into" anything.
Rotaree said:
Getragdogleg said:
Eric Mc said:
TwigtheWonderkid said:
What is the universe expanding into?
Not a relevant question.It does not need to expand "into" anything.
Rotaree said:
Getragdogleg said:
Eric Mc said:
TwigtheWonderkid said:
What is the universe expanding into?
Not a relevant question.It does not need to expand "into" anything.
ewenm said:
Nothing, the Universe is everything (by definition!). The Universe isn't an object expanding in static space, the space itself is expanding.
Nope, sorry, much as I"'d like to, I'm still not grasping the concept. I suspect there isn't going to be an easily graspable way of explaining this one!The expansion may be into other dimensional space/time - something us three dimensional beings find impossible to envisage.
I always think the analogy of the two dimensional inhabitants of Flatland finding it difficult to visualise a third dimension is the best way of trying to relate to this.
I always think the analogy of the two dimensional inhabitants of Flatland finding it difficult to visualise a third dimension is the best way of trying to relate to this.
Eric Mc said:
The expansion may be into other dimensional space/time - something us three dimensional beings find impossible to envisage.
I always think the analogy of the two dimensional inhabitants of Flatland finding it difficult to visualise a third dimension is the best way of trying to relate to this.
That epidode of "The Cosmos", where Carl Sagan goes on to demonstrate hyper-cubes as being 'shadows' of 4 dimensional shapes was pretty much the most convincing proof I ever saw for the existence of dimensions beyond our understanding...I always think the analogy of the two dimensional inhabitants of Flatland finding it difficult to visualise a third dimension is the best way of trying to relate to this.
Rotaree said:
ewenm said:
Nothing, the Universe is everything (by definition!). The Universe isn't an object expanding in static space, the space itself is expanding.
Nope, sorry, much as I"'d like to, I'm still not grasping the concept. I suspect there isn't going to be an easily graspable way of explaining this one!Gassing Station | Science! | Top of Page | What's New | My Stuff