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

  • Context: Undergrad 
  • Thread starter Thread starter quarkman
  • Start date Start date
  • Tags Tags
    Iron
Click For Summary

Discussion Overview

The discussion centers around the concept of why matter in the universe is said to "want" to become iron, referencing ideas from nuclear physics and stellar processes. Participants explore the implications of nuclear binding energy, the stability of elements, and the fate of matter in the universe over astronomical timescales.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants note that fusion of elements lighter than iron releases energy, while fusion into iron does not yield an energy surplus, which may explain why matter tends toward iron.
  • One participant mentions that iron is the most tightly bound nucleus, suggesting that systems prefer to be in their lowest energy state, which for nuclei is iron.
  • A historical perspective is provided regarding the nuclear shell model and the potential stability of elements beyond iron, with references to elements 116 and 118 possibly being stable.
  • There is a discussion about the future of the universe, where some speculate that if it continues to expand indefinitely, all matter may eventually become iron, contingent on various cosmological assumptions.
  • Participants discuss the stability of protons and the implications of proton decay on the long-term fate of matter in the universe.
  • One participant recalls an experiment designed to detect proton decay, questioning its success and relevance to the discussion.

Areas of Agreement / Disagreement

Participants express a range of views on the stability of elements and the implications of nuclear processes, with no consensus reached on the ultimate fate of matter or the interpretations of the statements regarding iron.

Contextual Notes

Some statements rely on assumptions about cosmological models and the stability of protons, which remain unresolved in the discussion.

quarkman
Messages
40
Reaction score
0
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?
 
Physics news on Phys.org
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.
 
Last edited:
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
 
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
 
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
 
114-118 are more stable, yet still unstable. :)
 
Arctic Fox said:
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.
 
good book
ive read it.
have you read the elegant universe by brian greene? even better book!
 
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.
 
  • #10
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
 
  • #11
jamie said:
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.
 
  • #12
quarkman said:
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.
 
  • #13
Mk said:
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.
 
  • #14
quarkman said:
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.
 
  • #15
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! :frown:
 
  • #16
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.
 
  • #17
whydoyouwanttoknow said:
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 :eek:
 
  • #18
Nereid said:
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 :eek:

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.
 
  • #19
whydoyouwanttoknow said:
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'.
 
  • #20
Nereid said:
Perhaps you are thinking of the IMB experiment?

That sounds like it.
 

Similar threads

Undergrad What are the possible states of cold iron balls?
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad The initial density of an object and its compression into a black hole
  • · Replies 17 ·
Replies
17
Views
5K
Undergrad How Could Rarefied Space Matter Affect a Starship's Speed Near a Star?
  • · Replies 9 ·
Replies
9
Views
1K
Undergrad Why does the core collapse happen so fast in a supernova?
  • · Replies 3 ·
Replies
3
Views
3K
Undergrad Star formation and heavy elements
  • · Replies 19 ·
Replies
19
Views
5K
High School Conflict between the conservation of matter and the rapid expansion of our universe
  • · Replies 18 ·
Replies
18
Views
2K
High School Question regarding supermassive black holes in the early Universe
  • · Replies 1 ·
Replies
1
Views
3K
Graduate Does iron really kill fusion in stars?
  • · Replies 5 ·
Replies
5
Views
13K
Undergrad How does the Singularity produce all the diverse matter in the universe?
  • · Replies 9 ·
Replies
9
Views
2K
Undergrad Cosmological scale and the pressure of light....
  • · Replies 6 ·
Replies
6
Views
2K