How Old is the Universe??

[Soundbear]

Looking at a few separate "scientific facts".

The universe is 12 to 14 billion years old.

It started with a Big Bang and has expanded since.

The Hubble Telescope has detected objects apparently 12 billion light years away.

The question? How did the objects get so far away in so short a time??

[NewCasa]

If the furthest objects (and I'm not saying Hubble has found the furthest - just saying this for arguements' sake) are 12 billion light years away and the universe is 12 billion years old, then it stands to reason that any objects going directly away from us (ie. furthest objects) are travelling at 1/2 the speed of light.

Now, the BIG question is - what was there BEFORE the big bang?

[Babzz]

Don't think we will ever know...

[Konig-OV]

But it's the "drive" to know is what caused the creation of fictional characters, such as god, and religion to form.

Easiest way to answer that question is to say, Something beyond us had to of created it

[Soundbear]

If the furthest objects (and I'm not saying Hubble has found the furthest - just saying this for arguements' sake) are 12 billion light years away and the universe is 12 billion years old, then it stands to reason that any objects going directly away from us (ie. furthest objects) are travelling at 1/2 the speed of light.

Now wait a sec. Figure this. The light from these objects has been travelling for 12 billion years. That means they were 12 billion light years from here 12 billion years ago.

But the universe is only 12 to 14 billion years old.

See my problem??

[BlueSky]

Barry, I am not very educated in these matters. But think of a cluster of stars in a centre, being flung out by centrifugal force. The light that we now see is the light that was much closer to the centre 12 billion years ago. It's not as if those sources of light turned on once they got into position. They were not dark lumps of coal that turned into stars out there. Do you get my meaning?

So the source of the light that we see NOW could have originated much closer to its point of origin. That would be my simplistic explanation.

Another possibility is that the speed of light may not not be constant. I don't know whether that theory has been disproven. I know that is quite a controversial one.

[Soundbear]

No, Bluesky, the light we see now is the light that those stars put out, from where they were, 12 billion years ago, which was 12 billion light years away. The SOURCE has probably moved even further away.

I've always been interested in astronomy.

[Soundbear]

Nothing we know (according to Einstein's theory of relativity) travels through space, faster than light. That being 186000 miles per second. But that does not limit the speed at which space itself expands or is expanding. And by space expanding, it pulls everything along for the ride with it.

When the big bang first occured, it's suspected that the initial explosion/expansion was something like 300000000000000000000000000x faster than the speed of light.

Just wondering, do you have a source for that??

[Nihilistic Heathen]

Looking at a few separate "scientific facts".

The universe is 12 to 14 billion years old.

It started with a Big Bang and has expanded since.

The Hubble Telescope has detected objects apparently 12 billion light years away.

The question? How did the objects get so far away in so short a time??

f the Universe is only 14 billion years old, how can we see objects that are now 47 billion light years away?

When talking about the distance of a moving object, we mean the spatial separation NOW, with the positions of both objects specified at the current time. In an expanding Universe this distance NOW is larger than the speed of light times the light travel time due to the increase of separations between objects as the Universe expands. This is not due to any change in the units of space and time, but just caused by things being farther apart now than they used to be.

What is the distance NOW to the most distant thing we can see? Let's take the age of the Universe to be 14 billion years. In that time light travels 14 billion light years, and some people stop here. But the distance has grown since the light traveled. The average time when the light was traveling was 7 billion years ago. For the critical density case, the scale factor for the Universe goes like the 2/3 power of the time since the Big Bang, so the Universe has grown by a factor of 22/3 = 1.59 since the midpoint of the light's trip. But the size of the Universe changes continuously, so we should divide the light's trip into short intervals. First take two intervals: 7 billion years at an average time 10.5 billion years after the Big Bang, which gives 7 billion light years that have grown by a factor of 1/(0.75)2/3 = 1.21, plus another 7 billion light years at an average time 3.5 billion years after the Big Bang, which has grown by a factor of 42/3 = 2.52. Thus with 1 interval we got 1.59*14 = 22.3 billion light years, while with two intervals we get 7*(1.21+2.52) = 26.1 billion light years. With 8192 intervals we get 41 billion light years. In the limit of very many time intervals we get 42 billion light years. With calculus this whole paragraph reduces to this.

Another way of seeing this is to consider a photon and a galaxy 42 billion light years away from us now, 14 billion years after the Big Bang. The distance of this photon satisfies D = 3ct. If we wait for 0.1 billion years, the Universe will grow by a factor of (14.1/14)2/3 = 1.0048, so the galaxy will be 1.0048*42 = 42.2 billion light years away. But the light will have traveled 0.1 billion light years further than the galaxy because it moves at the speed of light relative to the matter in its vicinity and will thus be at D = 42.3 billion light years, so D = 3ct is still satisfied.

If the Universe does not have the critical density then the distance is different, and for the low densities that are more likely the distance NOW to the most distant object we can see is bigger than 3 times the speed of light times the age of the Universe. The current best fit model which has an accelerating expansion gives a maximum distance we can see of 47 billion light years.

Source: http://www.astro.ucla.edu/~wright/cosmology_faq.html#DN

[Konig-OV]

I told him, and I heard it from my God.

[NewCasa]

Now wait a sec. Figure this. The light from these objects has been travelling for 12 billion years. That means they were 12 billion light years from here 12 billion years ago.

But the universe is only 12 to 14 billion years old.

See my problem??

Yes, good point. Obviously my math is flawed - not too much of a surprise!

[NewCasa]

Barry, I am not very educated in these matters. But think of a cluster of stars in a centre, being flung out by centrifugal force. The light that we now see is the light that was much closer to the centre 12 billion years ago. It's not as if those sources of light turned on once they got into position. They were not dark lumps of coal that turned into stars out there. Do you get my meaning?

So the source of the light that we see NOW could have originated much closer to its point of origin. That would be my simplistic explanation.

Another possibility is that the speed of light may not not be constant. I don't know whether that theory has been disproven. I know that is quite a controversial one.

And the other theory I've heard (though I'm far from an expert on it) is that the universe is curved in such a way that objects further from the centre are actually not as far apart as they might be. I suppose the example would be an orange - if you were located on the outside of the skin and had to go to the centre to reach another place on the orange you would go a longer route than just going straight there. Not sure if I've got that right - Stephen Hawking I'm not.

On another note, why is this in Religion - isn't it physics?

[GRUMPY]

thats where warp speed comes in from Star Trek I guess.

[BlueSky]

nocasa said:

On another note, why is this in Religion - isn't it physics?

The question of origins usually turns into a religious discussion. I am sure this one will too. Besides, we have relaxed a little about off topic stuff.

[NewCasa]

May the schwarz be with you.....

[BlueSky]

May the schwarz be with you.....

????

[NewCasa]

See: Spaceballs.... (it's a movie, not an insult, btw)

[Soundbear]

f the Universe is only 14 billion years old, how can we see objects that are now 47 billion light years away?

When talking about the distance of a moving object, we mean the spatial separation NOW, with the positions of both objects specified at the current time. In an expanding Universe this distance NOW is larger than the speed of light times the light travel time due to the increase of separations between objects as the Universe expands. This is not due to any change in the units of space and time, but just caused by things being farther apart now than they used to be.

What is the distance NOW to the most distant thing we can see? Let's take the age of the Universe to be 14 billion years. In that time light travels 14 billion light years, and some people stop here. But the distance has grown since the light traveled. The average time when the light was traveling was 7 billion years ago. For the critical density case, the scale factor for the Universe goes like the 2/3 power of the time since the Big Bang, so the Universe has grown by a factor of 22/3 = 1.59 since the midpoint of the light's trip. But the size of the Universe changes continuously, so we should divide the light's trip into short intervals. First take two intervals: 7 billion years at an average time 10.5 billion years after the Big Bang, which gives 7 billion light years that have grown by a factor of 1/(0.75)2/3 = 1.21, plus another 7 billion light years at an average time 3.5 billion years after the Big Bang, which has grown by a factor of 42/3 = 2.52. Thus with 1 interval we got 1.59*14 = 22.3 billion light years, while with two intervals we get 7*(1.21+2.52) = 26.1 billion light years. With 8192 intervals we get 41 billion light years. In the limit of very many time intervals we get 42 billion light years. With calculus this whole paragraph reduces to this.

Another way of seeing this is to consider a photon and a galaxy 42 billion light years away from us now, 14 billion years after the Big Bang. The distance of this photon satisfies D = 3ct. If we wait for 0.1 billion years, the Universe will grow by a factor of (14.1/14)2/3 = 1.0048, so the galaxy will be 1.0048*42 = 42.2 billion light years away. But the light will have traveled 0.1 billion light years further than the galaxy because it moves at the speed of light relative to the matter in its vicinity and will thus be at D = 42.3 billion light years, so D = 3ct is still satisfied.

If the Universe does not have the critical density then the distance is different, and for the low densities that are more likely the distance NOW to the most distant object we can see is bigger than 3 times the speed of light times the age of the Universe. The current best fit model which has an accelerating expansion gives a maximum distance we can see of 47 billion light years.

Source: http://www.astro.ucla.edu/~wright/cosmology_faq.html#DN

If I ever saw a "baffle 'em with bull****" article, this is it. I'll be studying this for a week.

[Hans]

Barry. One of the things Einstein found is that when 2 objects travel away from each other at the speed of light, the distance between them is strangely enough the speed of light, and not 2 times the speed of light.

[Soundbear]

Barry. One of the things Einstein found is that when 2 objects travel away from each other at the speed of light, the distance between them is strangely enough the speed of light, and not 2 times the speed of light.

There seems to be a lot of understanding about what Einstien "found" but not very many links to show.