Age of the universe.

To the best of my knowledge, scientists estimate the age of the universe by adding a few billion years to the distance (in light-years) to the most distant abjects we can see with our most powerful telescopes. The few billion years is added because they figure it took that long after the Big Bang for the first stars and galaxies to form.

That being the case, if the most distant object we can detect is a quasar or a galaxy and we measure it's distance as being 15 billion light-years away (the light we are seeing left that object 15 billion years ago) and we add 2 or 3 billion years we can estimate that our universe is about 18 billion years old.

Does anyone know if this is really the way they estimate the age of the universe? If it's wrong, then can anyone offer a simple explanation of how they do it? If it is correct, then I have a follow-up question.

that seems to be the generally accepted method. However, you will get several guesses in a range from 12-20 billion years.
20 years ago, it was 8-10 billion. Maybe in 20 years it will be 50 billion. The more powerfull our telescopes, the deeper in our past we can see, and calculate.

Aye captain, I think that roughly how they do it. If I remember correctly, the furthest images taken by Hubble have been just over 13 billion light years away, and estimates go up to around the 20 b.l.y. range for the age of the universe.

It's age can only get more accurate, as stated by toolmaker's post. Howstuffworks.com estimates the age of the universe as 14-15 billion years.

I've read that scientists figure out the age of the universe by the occuring radiation caused by the big bang, from what I've read the universe is anywhere between 15 and 20 billion years old.

Okay, my follow-up question. According to what I've read, from where we sit in the universe, we can see (in every direction) objects which are up to about 12 billion light-years away. Let's say that the most distant object we can see while looking into the Northern sky at midnight on Jan 1st is 12 billion light-years away and we call it object "A". At exactly the same time someone in the observatory right next to us, looks into the Southern sky and sees object "B" which is also about 12 billion light-years distant from us. From those observations we thus estimate the age of our universe at 15+ billion years old. But what if there is intelligent life on object "A" (or more likely a planet orbiting "A") and suppose an alien on that planet points his EXTREMELY powerful telescope at us and measures that we are 12 billion years away from him, and then if he moves his telescope just a bit more and sees object "B" which is an additional 12 billion light-years distant. Wouldn't he measure the age of the universe as being more than 24 billion years old?

[edit on 2-1-2005 by Senator]

How can one put an age on the universe. What was there before the universe? It had to always be there, which doesn't seem feasable. It extends in every given direction and never ends. We can give it an age but it obvioulsy is not correct but for science purpose it is what we have to accept.

Originally posted by I See You
How can one put an age on the universe. What was there before the universe?

They'd be also no way of telling the true age of the universe as this present universe may be just a cycle of the whole.. it could be 500 billion years old [if indeed it has a beginning] if it is in cycles of exploding, imploding- transforming etc. The big bang might not be it's beggining.. just the beginning of this cycle.




[edit on 2-1-2005 by riley]

Riley. I agree with you. I don't think this has happened only once. I believe they call that an 'oscillating' universe (a Big Bang, followed by expansion, then slowing and stopping, then contracting and then doing it all over again) . But if that is the case, then, when it's totally contracted right down to a nothingness (possibly a 'singularity), there could be no time. If there's nothing (or only a singularity) there, then there's nothing to move or change, so there's no passage of time. If that is the case, then we cannot ask 'what happened BEFORE the Big Bang because the word BEFORE denotes time passing and at the contraction there is no passage of time. The age of the universe would start with the current Big Bang when time would be started (or perhaps re-started).

After the Big Bang, space exists only within the area where the Big Bang has expanded. Outside of that there is nothing (because there's no 'outside of that') - not even empty space. I've read that although the universe is expanding, it's not an expansion like a bomb going off. Instead of expanding into an area outside it's previous area, it's just the space within the present universe (between stars, galaxies, quasars, etc) that's growing. Of course that makes it look like it's exploding like a bomb would. The difference is that shrapnel from the exploding bomb goes flying off into an area that was already there before the explosion whereas the universe just grows the space between it's stellar objects.

I find it extremely difficult to get my mind around NO TIME and NO SPACE and not understanding it completely I'm sure my foregoing explanation leaves a lot to be desired. That's just the way 'I' understand it and there's every possibility that I'm completely wrong.

Originally posted by Senator
Riley. I agree with you. I don't think this has happened only once. I believe they call that an 'oscillating' universe (a Big Bang, followed by expansion, then slowing and stopping, then contracting and then doing it all over again) . But if that is the case, then, when it's totally contracted right down to a nothingness (possibly a 'singularity), there could be no time.

Yes.. possibly it could be something like a black hole.. but I haven't really read up on what happens to black holes when they get 'full'.. whether they are self contain or fed into another 'undercurrent' reality.. or become so dense that they explode? If indeed it is just a single point and there are no other real universes [real as in they might be just giant galaxies] ..that single point may be a fraction of a millimetre.. so there is actual width to it and therefore space and time inside it. Hope that makes sense.. I wish I could put losts of equations up to make it sound better.. I kind of just think visually when it comes to science. It's hard to translate.

If there's nothing (or only a singularity) there, then there's nothing to move or change, so there's no passage of time. If that is the case, then we cannot ask 'what happened BEFORE the Big Bang because the word BEFORE denotes time passing and at the contraction there is no passage of time. The age of the universe would start with the current Big Bang when time would be started (or perhaps re-started).

I have difficulty grasping the time restarting thing.. if there was a universe before us.. and it eploded and expanded the same way.. and evolved the same way.. have we been here before?

After the Big Bang, space exists only within the area where the Big Bang has expanded. Outside of that there is nothing (because there's no 'outside of that') - not even empty space.

But what would be the 'barrier'?

I find it extremely difficult to get my mind around NO TIME and NO SPACE and not understanding it completely I'm sure my foregoing explanation leaves a lot to be desired.

The problem is that as animals we percieve time as the thing between birth and death.. so we naturally think it must begin somewhere.. I think thats also why many feel there has to be a creator god because they can't imagine not having a parent. Also 'space' is walking 'over there' so it's difficult trying to comprehend nothing 'over there'.

That's just the way 'I' understand it and there's every possibility that I'm completely wrong.

As it is the opinions here are just as valid as the most accomplished scientists.. because when it comes down to it they haven't got enough info themselves to really conclude anything for sure.. and there is probably a limit on how much they can gather as physics pre big bang [where there is not time and space for there to be any ] may not share the same patterns.
My brain is in a feedback loop now. I can kind of imagine why some methematicians give in and say 'god done it'. [not that I am!]

The problem with the theory of a Big Crunch where the universe collapes is that infact the universe isnt slowing down but speeding up.

I've heard that too Smokey. It looks like the expansion of the universe is speeding up (either that or the space between stellar objects is growing at a faster rate than it was in the past which, for all intents and purposes, is the same thing). In order for them to have determined that it's speeding up, they'd have to know how fast it was expanding at some time in the past and, at that earlier time, it had to be expanding more slowly than it does right now. That means that the speed of expansion 'varies'. For one who believes in the 'oscillating universe' either a speed-up or a slow-down can be taken as evidence that iIf it can go faster, it can also go slower (or vice-versa). Perhaps when it goes slow enough it can stop and gravity can start crunching it back together again. If it could be shown that the universe was (and has been) expanding at a constant rate, I'd be inclined to rethink the probabily of an upcoming crunch but the speed variation I take as a good omen. If the universe is an oscillating one, we have absolutely no idea as to the average lifespan of this or any particular universe and if our present universe is +/- 20 billion years old now, then maybe we're still very young and in a couple hundred billion years we'll start our slow-down which might result in the crunch.

Originally posted by Senator
suppose an alien on that planet points his EXTREMELY powerful telescope at us and measures that we are 12 billion years away from him, and then if he moves his telescope just a bit more and sees object "B" which is an additional 12 billion light-years distant. Wouldn't he measure the age of the universe as being more than 24 billion years old?

Depends, is the alien looking at us NOW, or 12 billion years ago? if he is looking at us now, he see's what will be us 12 billion years ago. If he actaulyl wants to see use infesting earth, he probly has to be looking at us 12 billion years from now (or so) Remember the further we look into space using the visible light spectrum the further in the past things are. So we are never seeing the universe "NOW" but what it was. Even light from the sun is about 8 minutes old.

Remember, sceince is always using the Big Bang theroy as it's base, and trying to find the "smoking gun" of it's existance. One of the problems of looking into the past and trying to determine age, is being able to make sense of anything you see.

I don't know this, but how accurate are the measurements of distant stellar objects at over 10 billion light-year distance?

man you guys gave me three headaches

This is all assuming of course, that the bit of the universe we can detect is

1. ALL of it
2. not just another "grouping" beyong the galaxy clutters. For example, first, we thought there was only the solar system. Then we learned there are many solar systems in a galaxy, then we learned there are many galaxies often in a cluster. Who's to say all of the galactic clusters we know of, aren't simply part of an even larger group, but one much smaller than the universe itself? Perhaps such a group (our such group) sprouted from a "big bang", and perhaps other such groups did too, though far beyond our current ability to detect?

I see what you mean. Since our solar system is estimated to be about 5 billion years old, any alien in a star system more than 5 billion light years away from us could point his telescope right at us but he would see nothing here, at least (from his perspective) not yet.

I don't know why that hadn't occurred to me.

I don't know how accurately they can measure extreme distances and although I think I understand how they use the red shift of light to estimate astronomical distances, on TV today I saw a scientist talking about how they're now using super novae of NEUTRON stars to measure those distances.

Actually, folks, scientists don't use ONE way of measuring the age of the universe: they use several.

Scientists dislike taking as "fact" an single measure (which is why in archaeology, Carbon Dating is seldom used as the "date" -- all dating methods are generally done by a main technique and backed up by a secondary technique.) The same is true with the measures of the size and age of the universe.

Currently they do use distance, but they also use estimates based on the Hubble Constant. A few have also used background radiation for the estimates.

imagine.gsfc.nasa.gov...

www.csiro.au...

So they didn't use one simple idea for the estimate. They used several estimates and in order to confirm, a lot of complex and increasingly precise measurements were used (measurements which have to be rechecked and confirmed by people not associated with them.)

the universe can be 9999999999999999 trillion years old, and it can be 5K years old. after all, what solid hard proof do we have its not? I admit, the stars are pretty good guesses and more like facts, but if u believe in God, God can just make the light automatically there.

Now Astronomers are saying it is small, finite, doughnut shaped and 56 billion light years across.

They used three techniques to compare predictions of how the cosmic microwave background's temperature fluctuations in different areas of the sky should match up in both an infinite Universe and a doughnut one. In each case, the doughnut gave the best match to the Wilkinson Microwave Anisotropy Probe data.

via KurzweilAI.net

I don't think anyone "really" knows. I think it's a bit too much thinking we can figure everything out so quick, I mean this is the entire universe we are talking about, we have not explored 0000.1% of it, and we think we are all knowing.