# Age of Universe

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### #1 rockgilla

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Posted 25 May 2004 - 07:37 PM

Can anyone help me with these physics questions.
How is the age of the universe determined?
When were the stars formed?
When was the earth formed?
How is te age of rocks determined?
How is the age of fossils determined?
The date of the earliest evidence of life on earth?
The dates that dinosaurs existed on eart?
The date of the earliest evidence of human life on earth?
How did life evolve on earth eg.How first molecules that could reproduce themselves came to exist?
How did life elove on earth?
How did life begin on earth?

Any help would be greatly appreciated thanks.

### #2 Freethinker

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Posted 25 May 2004 - 08:50 PM

That's an interesting list. An extensive list. A curious list. And a familiar list.

Many of these things are related and explained together. What exactly are you trying to find out? Each one of these could be a discussion by itself that could go into great detail. It would seem obvious that there is an underlying motivation to this list. A more direct and specifically comprehensive answer could be provided if you brought the list down to the salient interests.

Keep it simple. Basically what are you trying to find out?

### #3 Bo

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Posted 26 May 2004 - 09:12 AM

Hi i'm new to these fora, but they all look rather interesting and i hope i can contribute something

for your questions: i'll give some of the more 'simple one sentence answers' (as far as i know them) If you want any more detail: just say so.

-How is the age of the universe determined?
There are various ways to do this. The easyest (but still some mathematics is needed) is by considering the follwing formula (some reformulation of hubble's law): Distence travelled since the big bang= speed* 1/H. Where H is hubble's constant. since the 'normal' formulation for 'distence travelled' is: disctence = speed*time. We can see 1/H as the time since the big bang. Observations show that this is about 9 billion years.

When were the stars formed?
-about 600 million years after the big bang

When was the earth formed?

How is te age of rocks determined?
How is the age of fossils determined?
-These are determined by the decay of certain radiactive materials (most times C14 is used).
We know for example what the 'natural' amount of C14 in a certain rock should be when it was created. Since we know how fast C14 decays, we can determine the age of the rock by looking at the present amount of C14

The date of the earliest evidence of life on earth?

The dates that dinosaurs existed on eart?
- dont know exactly; about 500 million years ago

The date of the earliest evidence of human life on earth?
- The so called homo sapiens ('thinking man') which is the species we 'are', is first dated some 150.000 years ago

How did life evolve on earth eg.How first molecules that could reproduce themselves came to exist?
-Dont know exactly...

Bo

### #4 Freethinker

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Posted 26 May 2004 - 01:27 PM

Thanks BO. And glad to have you here.

Also, thanks for providing some details for rockgilla. Perhaps it's my spidee sense tingling, but I would be willing to bet, from the list and composition, that rockgilla has just sat thru some psuedo-science Creationist ramblings and is anxious to show those horrible Atheist Evolutionists how wrong they are. Just waiting for factual info to be supplied so they can laugh at "our stupidity". And from history here, there is every chance that rockgilla won;t even come back to find out how we reply. And if we do, will leave shortly after they find out how completely empty their position is.

But I could be wrong.

### #5 rockgilla

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Posted 27 May 2004 - 05:08 PM

Exuse me, Im participating in a group project for my Yr 11 Physics Class and wanted some help or websites to answer some questions. I google searched a question click on a linkand found your site which i thought would be a great asset to me. I have no wish to prove anyone wrong (although maybe my friends projects). I have also found very conflicting veiwss on the age of the universe some say 4-5 billion some say 9 and my physics teacher says 15 billion.

### #6 Bo

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Posted 28 May 2004 - 07:34 AM

well 4 or 5 billion years is VERY low. if i might ask: where did you find these numbers?
some other methods and numbers:
-Hubble method (as described above) gives~13 billion years. - (sorry, i made a mistake in my previous answer ).
- However the hubble method asumes that the hubble constant is constant. This isn't the case. An estimate for the average hubble constant is about 2/3 of the original. This brings the age of the universe to~9 billion years.
- The above method doesn't take the fact that the expansion of the universe is slowed down by gravity into account. If we do this we come to ~14 billion years.
[Above discussion and numbers are taken from "Modern Cosmology" by A. liddle a nice error margin would be about 5% to 10% i think]

Recently (last year or so) the WMAP observations showed (by a different, more exact, method) that the best estimate they can make of the age of the universe is 13.7 billion years, with an error of 1% (!) (for the original (technical!!) paper: see http://arxiv.org/abs/astro-ph/0302209 )
So your teachers estimate of 15 billion years is a little bit to high...
Bo

### #7 Tormod

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Posted 28 May 2004 - 08:10 AM

Bo is right about the 13.7 bln years estimate. Here is a link to the WMPA project detailing the findings:

http://map.gsfc.nasa..._mm/mr_age.html

Sorry that I have not welcomed rockgilla and bo (I think) but anyway, welcome! I'm flat out in bed with the flu and only check up on the forums sporadically.

Tormod

### #8 Tormod

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Posted 28 May 2004 - 08:19 AM

I should also point out that the current theory is that the acceleration rate is *increasing*, not slowing down.

Here's an interesting interview:
http://www.abc.net.a...ies/s479513.htm

Tormod

### #9 rockgilla

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Posted 30 May 2004 - 10:33 PM

Thanks for your help ive decided to tey the hubble method but could you help me with the wording as i often make simple mistakes

<SPAN style="FONT-SIZE: 12pt; BACKGROUND: yellow; FONT-FAMILY: 'Times New Roman'; mso-fareast-font-family: 'Times New Roman'; mso-highlight: yellow; mso-ansi-language: EN-AU; mso-fareast-language: EN-US; mso-bidi-language: AR-SA">The age of the universe can be determined If the universe has expanded at a constant rate we can use V = <SUP>D</SUP>/<SUB>T </SUB>Where V is Velocity D is Distance T is Time This turns out to be <SUP>1</SUP>/<SUB>H</SUB></SPAN><SUB><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman'; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-AU; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"> </SPAN></SUB><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman'; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-AU; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"><SPAN style="mso-spacerun: yes"></SPAN>this is called the Hubble Method. However the Hubble method assumes that the Hubble constant is constant. This isn't the case. An estimate for the average hubble constant is about 2/3 of the original.

Thankyou for your help and I hope this is right</SPAN>

### #10 Bo

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Posted 01 June 2004 - 05:46 PM

well i think thats quite right. It may be nice to also quote Hubbles law: v = H*r where v is the velocity of a cosmological object and r is its distence to the earth. (that;s basicly where the method comes from). Also a note: i don;t think this is general known as hubble's method; thats just a name i made up...

Bo