Why Does All Matter in the Universe Want to Become Iron?

[quarkman]

I am currently reading "In Search of Schrodenger's Cat" by John Gribbon. In the book he refers to iron as the most desirable form of matter and that all the matter in the universe "wants" to become iron. I think I recall a professor describing the collapse of a star under gravity and the matter forming into iron, but I am fuzzy on this. Does anyone have an opinion/answer for me?

 

[LURCH]

Not sure exactly what was meant to buy those statements, but I can tell you that the fusion of elements lighter than iron yields energy, and can therefore be self-sustaining. Once fusion within a collapsing star begins fusing smaller elements into iron, no energy surplus results, there is no energy "profit" to this process, and so it cannot continue indefinitely.

The same holds true for the splitting of heavier elements. Split a really large atom like uranium or plutonium, and the amount of energy released is more than enough to split another one. This surplus steadily decreases as we work our way down the periodic table, and the atoms become more difficult to split. This process also ceases to yield energy surplus in the same general band of the periodic table, around iron.

Perhaps this is what Gribbon refers to, although he seems to be leaving out nickel.

 

[chroot]

Iron is the most tightly bound nucleus. You can make the argument about any system that it "prefers" to be the lowest energy state, which for nuclei would be iron.

- Warren

 

[Njorl]

I remember long ago, my university was hosting the nuclear shell model conference at the time (1983?), there was an idea floating about that the elements we know might just be one stable group of several. That if you went to 200+ nucleons, you might come up with stability again. The problem was that there were no stable intermediate steps.

Has anybody heard about this?

Njorl

 

[chroot]

Yes, that's true AFAIK.. I'm not sure I remember exactly, but I believe it is suspected that element number 116 or 118 will actually be stable. I can't remember where I read this, though. I'll see if I can find it.

- Warren

 

[Arctic Fox]

114-118 are more stable, yet still unstable. :)

 

[Antimatter]

114-118 are more stable, yet still unstable. :)

This is accurate.
Extrapolation over 50 (!) magnitudes of order of the Semi-empirical mass formula of Bethe-Bloch-WeIssacker , corrected with a gravity factor yields first stable nuclei at nuclei with a radius of a few kilometres, which, albeit obtained via a very crude method, corresponds to the order of magnitude of neutron stars.

 

[jamie]

good book
ive read it.
have you read the elegant universe by brian greene? even better book!

 

[quarkman]

No I have not read "The Elegant Universe"...It's on my list though. Have you read "The Character of Physical Law"? I'm actually trying to decide between these two books for my next "leisurely" reading.

 

[jamie]

no i have not but it would have to be a great book to be better than the elegant universe.
hey, i have an idea, buy both.
regards jamie

 

[Mk]

good book
ive read it.
have you read the elegant universe by brian greene? even better book!

Sorry, I didn't like The Elegant Universe," though I do recommend Hyperspace, by Michio Kaku, The Universe In a Nutshell, by Stephen Hawking, and I highly recommend Hacking Matter, by Wil something. Hacking Matter is about quantum dots and artificial atoms. The Universe in a Nutshell is an overview of cosmology, relitivity, and some string theory I belive. Hyperspace is about of theoretical physics.

 

[Mk]

No I have not read "The Elegant Universe"...It's on my list though. Have you read "The Character of Physical Law"? I'm actually trying to decide between these two books for my next "leisurely" reading.

For leirsurely I would recommend Hacking Matter and Hyperspace.

 

[vanesch]

Sorry, I didn't like The Elegant Universe," though I do recommend Hyperspace, by Michio Kaku,

To me, Hyperspace was a really silly book with a lot of buzzwords and no real content. On the contrary, "the elegant universe" is a very good popularisation, not only because it introduces some ideas of string theory, but also because of the very good overview of more standard physics. You really learn something about real physics in "the elegant universe". That cannot be said about Hyperspace.

cheers,
Patrick.

 

[vanesch]

No I have not read "The Elegant Universe"...It's on my list though. Have you read "The Character of Physical Law"? I'm actually trying to decide between these two books for my next "leisurely" reading.

I think that Feynman's little book is an absolute marvel, so go for it. It explains you the essence of physics, real physics, as compared to buzzword physics of which so many popular books are full. The elegant universe is also very good and no-nonsense, but if you have to choose, take Feynman.

cheers,
Patrick.

 

[quarkman]

If I ever get to the end of my reading list...I'll be dead!

Thanks for all the responses regarding books! I think I will read Feynman's book as he strikes me as a very intelligent and straightforward individual. I just hope his more scientific books will be as good as his verbal autobiography. I have heard his book on QED is stellar...is this true?

It's so difficult to decide what books to read!

 

[whydoyouwanttoknow]

I remember reading that if the universe suffers the fate where it will continue to expand forever then one day, many trillions or jillions of years from now every atom in the universe will be iron.

 

[Nereid]

I remember reading that if the universe suffers the fate where it will continue to expand forever then one day, many trillions or jillions of years from now every atom in the universe will be iron.

Assuming a whole bunch of things about cosmology (expansion forever, no Big Rip, ...) this *might* be a possible outcome ... of course, if the proton is not stable (it's half life is, IIRC, 'only' ~>10³⁸ years!), then the future of the universe will be a very dilute soup of neutrinos and very, very low energy photons, and a few 'positronium atoms' (electron + positron), whose size is approx that of today's universe

 

[whydoyouwanttoknow]

Assuming a whole bunch of things about cosmology (expansion forever, no Big Rip, ...) this *might* be a possible outcome ... of course, if the proton is not stable (it's half life is, IIRC, 'only' ~>10³⁸ years!), then the future of the universe will be a very dilute soup of neutrinos and very, very low energy photons, and a few 'positronium atoms' (electron + positron), whose size is approx that of today's universe

I think I remember reading about some experiment where they had a tank underground (so there was no light) full of water or something. The tank was big enough so that a few protons a year should decay. They set up some very senistive cameras to detect the flashes of light that would be given off when a proton decayed. I can't remember if the experiment worked or not.

 

[Nereid]

I think I remember reading about some experiment where they had a tank underground (so there was no light) full of water or something. The tank was big enough so that a few protons a year should decay. They set up some very senistive cameras to detect the flashes of light that would be given off when a proton decayed. I can't remember if the experiment worked or not.

Perhaps you are thinking of the IMB experiment?

This Wikipedia site gives the current observed limit on the proton half-life as ~> 10³⁵ years, and says that there are good theoretical reasons why protons and neutrons are not stable. More technically, if there is some kind of grand unified theory of the four forces (EM, gravity, strong, and weak), quarks (the constituents of protons and neutrons) will transform into leptons (e.g. electrons) by exchanging an extremely massive particle (~>10¹⁵ that of the proton?).

Now that neutrino oscillations have been confirmed (both locally - reactor and accelerator experiments - and in solar neutrinos), there is at least some indirect evidence that 'diamonds are not forever'.

 

[whydoyouwanttoknow]

Perhaps you are thinking of the IMB experiment?

That sounds like it.