Age of the Solar System

Wallis

For years I have accepted the common wisdom that "the elements making up the Earth are 4.5 bn years old, therefore the Earth is 4.5 bn years old."

But, upon thinking on this during Professor Brian Cox's excellent program about the evolution of things and the fact that the solar system is possibly 3rd generation matter, I realised that the 4.5 bn year Solar System timescale is a massive mistake. The elements were all created inside the supernova that created the dust cloud from which the solar system condensed. This means that the Solar System is hugely younger than the traditional 4.5 bn year life. The supernova not only had to happen and disperse, but condensation and coellescence time followed by accretion and planetary formation had to happen, all within that 4.5 bn year time-frame.

Therefore the Earth and the Solar System must be much younger than 4.5 bn years, perhaps only hundreds of millions of years. What say you all?

mathman

The 4.5 billion is based on good geological evidence.

What particular supernova are you referring to? When was is supposed to have occurred?

phinds

When you come up against something that flies so utterly in the face of established science, it is not a good idea to start off reaching different conclusions and stating them as correct but rather to start off with the assumption that you have made a mistake somewhere and try to find out where it is. If you have NOT made a mistake you will find the flaw in the established science, but that is very unlikely to happen. If you start off thinking that you have overturned established science you are likely to just end up embarrassed.

Chalnoth

The galaxy is much older than 4.5 billion years, and the massive stars that produce the heavier elements and seed them throughout the galaxy have very short lifetimes (sometimes hundreds even tens of millions of years).

Wallis

Is it that the accretion and planetary formation process involved remaking all the elements of the early Earth? Phinds, please embarrass me if you will. I cannot see another way.

Are there really not enough red giants around Chalnoth? They could produce all the end products required and in the quantities required for the solar system 4.5 bn years ago surely? I cannot yet see a flaw. Why is the conventional answer so different?

Mathman, the supernova is the one Prof. Cox refers to in proposing that the Earth and entire solar system are made of stardust, as it can only be. The heavier elements are only made inside stars, and there's only one way for matter to permanently leave a star in large quantities.

Radio isotope analysis puts the earliest (not latest) elements composing the Earth at about 4.5 bn years old.

Chalnoth

Um, no. The energy involved in the formation of the solar system was far, far too low to fuse even hydrogen to helium, let alone the heavier elements.

There are tons of them. New ones are born all the time.

The point is that stars were being born and died for billions of years before our solar system formed, seeding the local area with heavier elements.

phyzguy

You're missing the whole point of how radioisotope dating works. There is no way to tell by looking at a particular element how long ago it formed. The key is that when solid minerals crystallize out of molten material, they chemically differentiate so that they are a relatively pure chemical substance. This basically 'starts the clock'. After the solid mineral is formed, any nuclei that decay are trapped in the crystalline matrix, so that by looking at the ratio of the original elements to the decay products you can tell how long it has been since the mineral crystallized. Note that you are measuring how long it has been since the mineral crystallized, not how long it has been since the elements formed in the heart of a supernova. This is all explained in any book on radioisotope dating. You could start here:

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

D H

What he said.

The first thing you should do, and the second, and the third thing you should do when you "you come up against something that flies so utterly in the face of established science" is think "What did I do wrong?"

What you did wrong was to
- Ignore the age of the universe.
- Ignore that massive stars are rather short-lived.
- Ignore that the first generation of stars were extremely short-lived.

Our solar system is almost certainly third generation, but it may well be fourth generation, or even more. The ten billion plus years between the birth of the universe to the formation of our solar system is a long, long, long time.

qraal

There's no mistake, just a misunderstanding of when the clock starts. The radioactive dating which is used to date meteorites, and thus the Earth, is only valid if the isotopes being compared have condensed and been trapped in solid minerals. Thus the age is not of the supernova, but of the condensation of the nebula itself into mineral grains. However the time between the supernova and condensation process can be estimated from the pattern of incorporation of short-lived isotopes, chiefly aluminum-26, which provided much of the heat that melted the asteroids not long after they formed. Only a few million years are required between the detonation of the supernova donor of Al-26 and the formation of the asteroids, with the planets then forming in 50-100 million years after that. So even if the heavy elements were all produced in the one supernova, the time between that and their incorporation into planets is mere millions of years.

As for all the knee-jerk replies from other PF posters please don't be put off. We are a bit friendlier than we might seem at first bark.

Naty1

what phyzguy said.

plus it's "supernovas"....rather than "...the supernova...."

Get ready for a likely citation....posting personal theories is against rigidly enforced rules.

Chalnoth

Just to drive this point home, if I take a piece of rock and melt it, then let it cool again, its radioactive clock will be reset. This is why we say our solar system is 4.5 billion years old: that's when stuff within our solar system solidified.

phinds

Well, if you want to be picky about it, it's really "supernovae", although we here in casual modern times do accept supernovas since we have long since adopted the point of view that if you can't beat the linguistic cretins (and you CAN'T) to hell with it ... just join them.

Wallis

Okay, so closure temperature is a new concept to me. However, the relevant section in the article begins with a big IF.

"If a material that selectively rejects the daughter nuclide is heated, any daughter nuclides that have been accumulated over time will be lost through diffusion, setting the isotopic "clock" to zero."

Presumably, the unpublished part of radiometric dates is the establishment of closure temperatures for the elements under scrutiny and an inscrutable proof that the parent nuclide WILL reject the daughter products... This is not made clear.

Case closed.

Chalnoth

Case closed? Do you somehow think that this puts radiometric dating into doubt? Or am I misunderstanding you?

Wallis

Thanks Chalnoth; do not frett,

I am saying this thread is closed. The possibility that worried me in my initial assertion - is resolved in the information on the ambiguities in reporting radiometric-dating. In not including the closure date and the reasons why daughter nuclides would be rejected from the bulk material, radiometric dating has not fully supplied the results of its exponents' careful analyses. It would be aposite to record full information on a result rather than a single date, or bracket of dates.

salvestrom

Stop and take a really deep breath wallis and let it out slowly. You keep quoting the age of our solar system. 4.5. 4.5. 4.5. What everyone here wants you to do is look at this number:

13.7.

Thats the age of the universe. Three times longer. Our galaxiy is nearly as old. Take this information and think on it.

phinds

+1 on that. The best current estimates are that the milky way was a very early galaxy, probably formed around 12 billion years ago, maybe a little longer.