Age of the Earth 2

[ChrisChrusherComix]

SA,

I'll do my best. But you know I'm a painter and not a scientist. Ha.

~ martin

Calling mscoville... are you there, sir? Hello? Marty?!?! Answer me! Please!

I can't PM or email my old friend here... any ideas?

[ayin jade]

Your friend hasnt been on here since:

Last Active 24th August 2004 - 08:13 AM

Almost 2 years. Now you have more than 10 posts, so you could try emailing him through the boards, however, it is more than likely his email account has changed. That is the only way I can think of to try and contact him.

[ChrisChrusherComix]

Your friend hasnt been on here since:

Last Active 24th August 2004 - 08:13 AM

Almost 2 years. Now you have more than 10 posts, so you could try emailing him through the boards, however, it is more than likely his email account has changed. That is the only way I can think of to try and contact him.

Yep. It has been like this for years now. I find him, and then he's gone and changes his email account or he abandons his message board identity before I can make contact with him. He's an old art school friend and I haven't seen him in years. I'm trying to locate him to see if he would be interested in collaborating on some Christian artistic efforts. Well... I'll keep trying. God bless!

[Bread_of_Life]

Wowee this post is old. There's some good stuff here though! Great to read some of my old posts

[Guest NewPilgrim]

How do you know that the decay is stable for tens of millions of years, or for that matter, even a few hundred?

[Bread_of_Life]

New Pilgrim,

Good question. There are various ways that we know that.

1. Theoretical reasons: We know what causes radioactive decay - and therefore we know that very basic constants of the universe would have to change in order for decay rates to change. For example, things can't just heat up - heat and pressure don't affect radioactive decay significantly. We know that light conditions don't affect decay, or even the compounds that radioactive elements are in.

2. Real world testing: There are several tests we can do to find out about radioactive decay rates in the past. First off, we can look at starlight. Starlight tells us what happened on stars hundreds, thousands, even millions of years ago. We can see from that light radioactive decay occuring - and measure its rate. This tells us that the rate has been constant over time.

Secondly, there are "decay chains" that build up in rocks that contain Uranium. These build up when the daughter element of a decay is radioactive itself. Uranium decays to lead through a chain of about 13 intermediate compounds. The ratio of the elements in the chain is proportional to the decay rate of each element. That means that if the decay rate changes - the ratios change. However - at current decay rates, it takes around 3 million years for these chains to settle down to an equilibrium. That means that, if the decay rates had changed a lot in the last 3 million years, these chains wouldn't be at equilibrium. So by measuring the ratios of elements in these decay chains, and seeing that they are at equilibrium, we can know that they've not been disturbed in the last few million years.

There are other more complex methods of testing decay constants in the past - involving neutron absorbtion. If you're really interested, I can go into these.

3. Practical considerations: Radioactive decay involves the release of energy. Always. A lot of energy. So much, that radioactive decay is keeping the earth's core molten, even at present rates. If the rates had increased dramatically, this would have released a lot of heat, and would have melted the rocks that radioactive elements exist in - meaning these would date as young.

In fact, if decay rates had changed as much as some creationists would have you believe, the whole earth would have vaporised or melted. This obviously hasn't happened.

[Guest NewPilgrim]

alot of that went over my head. I'm sure its basic stuff to you, but my technical english is not greatly advanced. However. You said that you can measure radioactive decay from startlight that goes back millions of years. How do you know that the light from these is millions of years old? and also, assuming that it is millions of years old, how can we be confidant that the decay rate will still be the same from these stars in another few hundred years?

at current decay rates, it takes around 3 million years for these chains to settle down to an equilibrium. That means that, if the decay rates had changed a lot in the last 3 million years, these chains wouldn't be at equilibrium. So by measuring the ratios of elements in these decay chains, and seeing that they are at equilibrium, we can know that they've not been disturbed in the last few million years.

I need u you to give me a checklist on this one so I dont get lost:

1) So what you are saying is that we observe the current decay rate and when we assume that it is constant we can calculate that it takes 3 million years for these chains to stabillize

2)we can then look back 3 million years to apply this calculation

3)Counting forward from our minus 3 million mark, assuming that the decay is constant as previously established, we should find that these chains are at equilibrium and in fact we do.

If these summaries are correct it raises two questions for me.

1)How do we know at which part of the 3 million year timescale these decaying chains are that we observe and base our calculations on?

2)Do we observe current examples of decaying chains and also chains in equilibrium?

[Bread_of_Life]

Newpilgrim,

Okay, more good questions:

You said that you can measure radioactive decay from startlight that goes back millions of years. How do you know that the light from these is millions of years old?

Okay, the answer is that the stars we are observing we can calculate their distance from earth, and work out how long it took the light to get here.

Now I know that some creationists say "maybe the light was created "in transit", but as far as I'm concerned, that is God lying, by making up a false history that the star never actually went through and transmitting it to earth. I am assuming here, obviously, that God isn't a liar, and we aren't the victims of a big cosmic hoax.

and also, assuming that it is millions of years old, how can we be confidant that the decay rate will still be the same from these stars in another few hundred years?

Because we can measure light from a variety of stars, some millions, some hundreds of thousands, some tens of thousands, some thousands, some hundreds of light years away. In other words, we can get a pretty accurate picture of decay rates and many different instances in time.

1) So what you are saying is that we observe the current decay rate and when we assume that it is constant we can calculate that it takes 3 million years for these chains to stabillize

2)we can then look back 3 million years to apply this calculation

3)Counting forward from our minus 3 million mark, assuming that the decay is constant as previously established, we should find that these chains are at equilibrium and in fact we do.

Right, but we can also know that these chains haven't been disturbed by decay rates changing a lot within the last 2-3 million years. Say for example decay rates radically changed a few thousand years ago. That would have thrown all of these chains out of their equilibrium into a new configuration. Then, when decay rates changed back, they would have taken another 2-3 million years to recover the equilibrium for the current rates of decay.

Therefore we can confidently say that these *must* have been going at present rates of decay for at least 2-3 million years - because that's how long it takes to reach equilibrium with these rates of decay.

1)How do we know at which part of the 3 million year timescale these decaying chains are that we observe and base our calculations on?

Well, that's simple. There are mathematical equations that tell us:

(a) How long it will take for these chains to settle down to equilibrium.

(b) The ratio of each element in the chain at equilibrium

© The ratio of each element in the chain at any time BEFORE reaching equilibrium

Therefore what we can do is measure the ratios of each element in the chain, and know how close they are to reaching equilibrium, or if they're there already. If they're part of the way there, we can then know how long since the rock formed and the decay chain started building. And if they are there, we can know that they must have been undistured for at least 2-3 billion years.

2)Do we observe current examples of decaying chains and also chains in equilibrium?

Yes, many. Pretty much any rock that contains Uranium will have a decay chain at some stage towards reaching equilibrium. This method is actually used to date rocks under 3 million years old. Unfortunately, it can't be used to date older rocks, because all it can tell us is that they've been around for at least 3 million years - it can't tell the difference between a 6 and 9 million year old rock - so we have to use other methods.