Size of the universe question ?

Maybe some kind soul can answer this for me and tell me what I'm missing ?

If the universe is just under 14 billion years old how can it be (from
what I've read) 93 billion light years across ?

If nothing can exceed the speed of light then shouldn't the maximum
diameter be no more than the age x2 (assuming the universe expands at
the speed of light, which it doesn't).

I have a feeling the explanation will be something to do with the early
universe not obeying the laws we observe now, but I can't find any info
on the sites I found so far and it's bugging me !!

Thanks...

No_Spam wrote:

Maybe some kind soul can answer this for me and tell me what I'm missing ?

If the universe is just under 14 billion years old how can it be (from
what I've read) 93 billion light years across ?

If nothing can exceed the speed of light then shouldn't the maximum
diameter be no more than the age x2 (assuming the universe expands at
the speed of light, which it doesn't).

I have a feeling the explanation will be something to do with the early
universe not obeying the laws we observe now, but I can't find any info
on the sites I found so far and it's bugging me !!

Thanks...

According to this:

http://www.atlasoftheuniverse.com/bigbang.html

The matter was already there, the Big Bang just caused it to expand.

What gets me going, is if the universe *is* a universe, by definition it
must be infinite, surely? So how can it even have a size?

--
Andy Hewitt
http://web.mac.com/andrewhewitt1/

What gets me going, is if the universe *is* a universe, by definition it
must be infinite, surely? So how can it even have a size?

The surface area of a sphere is finite, even though it is unbounded.

"No_Spam" wrote in message
m...


Maybe some kind soul can answer this for me and tell me what I'm missing ?

If the universe is just under 14 billion years old how can it be (from
what I've read) 93 billion light years across ?

Have a look at Ned Wrights's Cosmology Page
This is the FAQ page.
http://www.astro.ucla.edu/~wright/cosmology_faq.html

If nothing can exceed the speed of light then shouldn't the maximum
diameter be no more than the age x2 (assuming the universe expands at the
speed of light, which it doesn't).

It sounds like you need to read this articles from the FAQ
"If the Universe is only 14 billion years old, how can we see objects that
are now 47 billion light years away?"
http://www.astro.ucla.edu/~wright/cosmology_faq.html#DN

The previous question
"If the Universe is only 14 billion years old, why isn't the most distant
object we can see 7 billion light years away?"
also includes a mention of the problems in having several possible
interpretations of the word 'distance' when referring to long periods of
time in a universe with a finite speed of light.

I have a feeling the explanation will be something to do with the early
universe not obeying the laws we observe now, but I can't find any info on
the sites I found so far and it's bugging me !!

newshound wrote:

What gets me going, is if the universe *is* a universe, by definition it
must be infinite, surely? So how can it even have a size?

The surface area of a sphere is finite, even though it is unbounded.

I should have said a *known* size.

Obviously we can only measure what we can see, but as is already shown,
by the missing mass, we can't see it all.

--
Andy Hewitt
http://web.mac.com/andrewhewitt1/

http://www.atlasoftheuniverse.com/bigbang.html

The matter was already there, the Big Bang just caused it to expand.

What gets me going, is if the universe *is* a universe, by definition it
must be infinite, surely? So how can it even have a size?

--
Andy Hewitt
http://web.mac.com/andrewhewitt1/


I would be interested to know where the 'matter' came from in the first
place. That makes my head hurt :-)
------------

Bob....

golddust wrote:
http://www.atlasoftheuniverse.com/bigbang.html

The matter was already there, the Big Bang just caused it to expand.

What gets me going, is if the universe *is* a universe, by definition it
must be infinite, surely? So how can it even have a size?

--
Andy Hewitt
http://web.mac.com/andrewhewitt1/


I would be interested to know where the 'matter' came from in the first
place. That makes my head hurt :-)

For the answer, and reasons for your head to /really/ hurt, read A Brief
History of Time.

No_Spam wrote in
m:

Maybe some kind soul can answer this for me and tell me what I'm
missing ?
If the universe is just under 14 billion years old how can it be (from
what I've read) 93 billion light years across ?
If nothing can exceed the speed of light then shouldn't the maximum
diameter be no more than the age x2 (assuming the universe expands at
the speed of light, which it doesn't).
I have a feeling the explanation will be something to do with the
early universe not obeying the laws we observe now, but I can't find
any info on the sites I found so far and it's bugging me !!
Thanks...

See Wright's Cosmology FAQ at:
http://www.astro.ucla.edu/~wright/cosmology_faq.html#DN

It is the difference between distance-then and distance-now. Most
galaxy distances in popular media are described in terms of distance-
then. It takes 2.4 million years for light to travel from the Andromeda
galaxy to reach Earth, so its distance is 2.4 million light-years.

This measurement of distance leaves out two factors:

1) The universe itself - the fabric of space and time - expands at
superluminal speeds. The speed-of-light limitation means that light
cannot move through normal vacum space at more than a set speed. It
does not mean that the fabric of space itself cannot be expanding at
more than the speed of light. Many distant galaxies are so red-shifted
that their apparent speed relative to the Earth appears to exceed the
speed of light. This is not actual measurement of light traveling at
superluminal speed. It is an artifact of the space through which the
light is transiting expanding at superluminal rates. Confused? I am.

2) A very distant galaxy - let's say one 1 billion light years distant -
has been moving for a billion years and is no longer physically located
at the same spot when the light left a billion years ago.

The comoving distance - or distance-now - is usually much larger than
the more oft quoted distance-then.

Distance-then and distance-now measure the same thing - how far away a
distant galaxy is - just by different methods.

- Canopus56

A more complicated explanation at wikipedia
http://en.wikipedia.org/wiki/Comoving_distance

--
Posted via a free Usenet account from http://www.teranews.com

Andy Hewitt wrote:
No_Spam wrote:

Maybe some kind soul can answer this for me and tell me what I'm missing ?

If the universe is just under 14 billion years old how can it be (from
what I've read) 93 billion light years across ?

If nothing can exceed the speed of light then shouldn't the maximum
diameter be no more than the age x2 (assuming the universe expands at
the speed of light, which it doesn't).

I have a feeling the explanation will be something to do with the early
universe not obeying the laws we observe now, but I can't find any info
on the sites I found so far and it's bugging me !!

Thanks...

According to this:

http://www.atlasoftheuniverse.com/bigbang.html

The matter was already there, the Big Bang just caused it to expand.

Ok, I've read that. Far easier than I thought.
What this says (answer 6) is that it's possible the the speed of
expansion can exceed the speed of light !!
In a way I can sort of see that working. If nothing with mass can
move faster than the speed of light it seem only reasonable that that
nothing (having zero mass) CAN move faster than the speed of light...

I think I might have to go for a lie down in a darkened room for a while
now...



What gets me going, is if the universe *is* a universe, by definition it
must be infinite, surely? So how can it even have a size?

But, surly it's only infinite because space is curved. If you could
somehow measure a straight line without the curvature getting in the way
you might find the 'edge' ??

No_Spam wrote:

[..]
According to this:

http://www.atlasoftheuniverse.com/bigbang.html

The matter was already there, the Big Bang just caused it to expand.

Ok, I've read that. Far easier than I thought.
What this says (answer 6) is that it's possible the the speed of
expansion can exceed the speed of light !!
In a way I can sort of see that working. If nothing with mass can
move faster than the speed of light it seem only reasonable that that
nothing (having zero mass) CAN move faster than the speed of light...

The way I read it, it only appears to be travelling faster than light.

I think I might have to go for a lie down in a darkened room for a while
now...

Or one filled with light! :-)

What gets me going, is if the universe *is* a universe, by definition it
must be infinite, surely? So how can it even have a size?

But, surly it's only infinite because space is curved. If you could
somehow measure a straight line without the curvature getting in the way
you might find the 'edge' ??

No, I just think, as humans, we can't comprehend 'infinite', so have to
try and put limits to the universe.

After all, nobody really knows all the answers, we can only go by what
is known at this time.

--
Andy Hewitt
http://web.mac.com/andrewhewitt1/