# The Naked Scientists Forum

### Author Topic: What is the age and size of the universe?  (Read 3842 times)

#### hoford

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##### What is the age and size of the universe?
« on: 09/12/2009 05:52:18 »
Help me figure this out.
1.   The age of the universe is “14 Billion years”
2.   I can “look” in many directions and see light from objects 13+ billion years old.
3.   The universe started out as a “singularity” that expanded at, say, the speed of light.
How did the object I am looking get 13+ billion light years away from me in less than 1 billion years?
It would seem that one of:
1.    Where we are and where the object is must have moved apart at 12x the speed of light?
2.   The universe is 27 billion years old.
3.   ????
Can anyone explain?

« Last Edit: 09/12/2009 17:34:02 by hoford »

#### chris

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##### Re: What is the age and size of the universe?
« Reply #1 on: 09/12/2009 08:14:46 »

Thanks

Chris

#### Fozzie

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##### Re: What is the age and size of the universe?
« Reply #2 on: 09/12/2009 10:00:12 »
How did the object I am looking get 13+ billion light years away from me in less than 1 billion years?

What gave you the idea that it took less than 1 billion years to get where it is now?

#### hoford

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##### Re: What is the age and size of the universe?
« Reply #3 on: 09/12/2009 12:21:04 »

If a galaxy is 13+ billion light years away light must take 13+ billion light years to get here.
Which means the galaxy must have been where it is 13+ billion years ago.

If the matter in the galaxy took X years move away from us since the start of the universe, the universe must be
at least X+13 billion years old
if x + 13 billion = 14 billion then X = 1 billion.

Put another way:

When astronomers say "the object is 13 billion light years away" what does it mean?

I assume light took 13 billion years to get here which means 13 billion years ago the object was 13 billion
light years away. Given a speed of light expansion of the universe, it would put the minimum age of the universe at 26 billion years.

If I can see 2 13 million year old objects in 2 opposite directions it would imply the universe is more than 39 billion years old.

I assume I am wrong (I have heard vague references to: Einstein, curve space time expansion etc.) but I in what way?

Hoford
ps.

Sorry about the inappropriate title. Should I just start a new thread os is there a way to change the title?

#### Vern

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##### Re: What is the age and size of the universe?
« Reply #4 on: 09/12/2009 12:21:49 »
Help me figure this out.
1.   The age of the universe is “14 Billion years”
2.   I can “look” in many directions and see light from objects 13+ billion years old.
3.   The universe started out as a “singularity” that expanded at, say, the speed of light.
How did the object I am looking get 13+ billion light years away from me in less than 1 billion years?
It would seem that one of:
1.    Where we are and where the object is must have moved apart at 12x the speed of light?
2.   The universe is 27 billion years old.
3.   ????
Can anyone explain?

It is even  more interesting than that. As you indicate, we see objects that are at least 27 billion light years away from us. The light that reaches us now started its journey 27 billion years ago. The object that generated the light is now 27 billion years older than it was when it sent the signal toward us. When we do spectrograph analysis of the light we find the presence of heavy metals that can not exist in first generation stars.

All of this indicates a normal universe in my mind. It is only a problem when you try to fit it with various creationist theories. The one that wants the universe to be about six thousand years old, failed early. The one that wants the universe to be about 13 billion years old, failed about fifty years ago.

#### Vern

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##### Re: What is the age and size of the universe?
« Reply #5 on: 09/12/2009 12:25:55 »
Quote
Sorry about the inappropriate title. Should I just start a new thread os is there a way to change the title?
Look at the opening paragraph. Above, in the upper right of the paragraph you will see a "modify" link. Click that link. In the page that opens, there will be the title at the top. Just click into the text area of the title, and change it to be whatever you like.

#### PhysBang

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##### Re: What is the age and size of the universe?
« Reply #6 on: 09/12/2009 12:50:46 »
1.   The age of the universe is “14 Billion years”
Roughly.
Quote
2.   I can “look” in many directions and see light from objects 13+ billion years old.
Determining the age of objects that old is a tough thing. There are significant error bars, so when someone claims the age of a particular object, one usually has to consider a range of at least one billion years on each side of that age.
Quote
3.   The universe started out as a “singularity” that expanded at, say, the speed of light.
The expansion near the singularity took place at much, much faster than the speed of light. This expansion is not movement, it is a geometrical effect. That is, the geometry of space and time itself changes, causing the expansion. This means that it is not limited to the ight speed limit.
Quote
How did the object I am looking get 13+ billion light years away from me in less than 1 billion years?
If you are looking at an object about 13 billion years old, it would be significantly farther away now than it was when the light left it and the light would have actually travelled more than 13 billion light years.

#### Nizzle

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##### Re: What is the age and size of the universe?
« Reply #7 on: 09/12/2009 12:54:43 »
Shouldn't a difference be made between "The Universe" and "The observable Universe"?

#### Mr. Scientist

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##### Re: What is the age and size of the universe?
« Reply #8 on: 09/12/2009 12:59:49 »
It's been near enough 14 billion years if we measure to a mathematical certainty that if there was a finite limit to the past that we know it must be around the given date due to what we can observe (or in a scientific term ''the observable universe.'')

#### Nizzle

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##### Re: What is the age and size of the universe?
« Reply #9 on: 09/12/2009 13:03:14 »
But maybe our observable universe is just one bubble in a bubble bath...

#### Mr. Scientist

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##### Re: What is the age and size of the universe?
« Reply #10 on: 09/12/2009 13:06:29 »
Well, funnily enough, we have found and extra source (which seems like) gravity pulling all the observable universe to another center! How large is our universe?

#### LeeE

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##### What is the age and size of the universe?
« Reply #11 on: 09/12/2009 20:31:26 »
Well, funnily enough, we have found and extra source (which seems like) gravity pulling all the observable universe to another center! How large is our universe?

Are you referring to the Great Attractor?  That appears to be located within the observable universe.

#### Mr. Scientist

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##### What is the age and size of the universe?
« Reply #12 on: 10/12/2009 04:08:40 »
Well, funnily enough, we have found and extra source (which seems like) gravity pulling all the observable universe to another center! How large is our universe?

Are you referring to the Great Attractor?  That appears to be located within the observable universe.

All observable systems are ''falling'' towards a central new region of force; i doubt its actually in the observable universe though lee. :)

#### PhysBang

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##### What is the age and size of the universe?
« Reply #13 on: 10/12/2009 14:22:00 »
According to some sets of observations, some of the universe appears to be systematically different from the rest of the universe. One explanation for this is that there is a large concentration of matter just out of our sight. Another explanation for this is that there is a statistical error in that particular set of observations.

http://en.wikipedia.org/wiki/Dark_flow

#### Farsight

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##### What is the age and size of the universe?
« Reply #14 on: 11/12/2009 16:30:14 »
It's really simple, hoford. Just find a stress ball and squeeze it down tight. Then let go and watch it. Do it a few times until you've got the hang of it. Now imagine a little ripple travelling through the stress ball as it expands. This is an analogy for light. It travels at the speed of light, but the expansion of the stress ball carries it along. At no point does the ripple travel faster than light through space, but the space it's travelling through is expanding, so when you look at it now, it looks as if it's travelled a lot more than 13.7 billion light years.

It's important to note that the universe is expanding faster than light. See http://en.wikipedia.org/wiki/Observable_universe and note that "The edge of the observable universe is now located about 46.5 billion light-years away". That means the universe has expanded at least 3 times as fast as light. Also note that we don't know that it started with a singularity. See http://en.wikipedia.org/wiki/Big_Bang on this.

Vern: general relativity and fundamental physics is telling me that space has this stress-energy, and stress is like pressure. There's nothing outside the universe to hold it all in, so it just has to expand.
« Last Edit: 11/12/2009 16:34:12 by Farsight »

#### The Naked Scientists Forum

##### What is the age and size of the universe?
« Reply #14 on: 11/12/2009 16:30:14 »