UKC

Carl Sagan said, "we are all made of star stuff". While I don't dispute that the only way heavy elements have formed in the universe is at the core of stars, and the only way this then gets redistributed amongst the universe in in supernova explosions, the time scales don't seem to add up.

If the universe is 13.3 bn years old and stars like our sun last around 10bn years, then how has there been enough time for stars to form, explode and then reform into our solar system in the 13.3bn years we have had.

Turns out I have just found the answer.

A quick bit of googling has revealed the answer, that more massive stars have much shorter life cycles, so massive stars of the type that end in supernova typically only last a few million years, so we have had plenty of time for plenty of supernova explosions to throw heavy elements into the galaxy to reform into our solar system.

Thought I would still post as I found it interesting, so thought you might!

In reply to ablackett:

Incredible to think really isn't it; that the atoms you are made of were formed in the 100 million degree core of a long dead star.

In reply to phja:


Well, a lot of them.

Some others will have been formed by radioactive decay of those, and yet more will have been formed during an even more amazing, less well understood, and probably much hotter event 13 billion years ago!

In reply to ablackett:

Sounds too far fetched to me. I know I'm made of snips and snails and puppy dogs tails. Stars -yerright.

In reply to gribble:

I hope they were star snails, at least.

In reply to ablackett:


Now that was a series I'd watch again, "Cosmos".

In reply to Fraser:

"Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves."

CS

In reply to Fraser:

It's a regular in our house when we need some soothing rationality - there's a particularly lovely scene where he's lecturing to a bunch of school kids. There's a newer (downloadable) version of the original where he expounds at the end of each episode on newer developments. His death was a great loss. 20 years ago - he's still as fresh now as he was then.
The newest version - a complete remake with Neil deGrasse Tyson (no slouch himself!) is pretty good but doesn't have quite the same sense of wonder.

In reply to ablackett:

What I like very much is that all the atoms we are made of are recycled again and again. That's real reincarnation!

In reply to Lusk:

This is worth a read - http://www.smithsonianmag.com/science-nature/why-carl-sagan-truly-irreplace...

In reply to ablackett:

Elements from iron onwards are formed in supernovas; the lighter elements formed by fusion, yielding energy. After this, fusion doesn't release energy (the iron limit). As the star hits the iron limit, it implodes, and may go supernova.

https://en.m.wikipedia.org/wiki/Iron_peak
http://abyss.uoregon.edu/~js/ast122/lectures/lec18.html

Note the timescales for the 'burning' of the heavier elements; carbon 600 years, neon one year, oxygen 6 months, silicon one day... BANG!

In reply to pneame:


I'll check it out, thanks for the heads-up.

In reply to ablackett:
I loved Cosmos but was Sagan really the originator of this idea? Joni Mitchell beat him to it in her 1970 song Woodstock, 'We are stardust, we are golden' etc. Not exactly the same but I think the idea, and variations of the quote, have been around for a long time.

In reply to Lusk:


A bit off-topic, but am I alone in thinking Hugo Weaving was borrowing from Sagan for his Agent Smith persona in The Matrix (the vocal mannerisms, not the ruthless megalomania)?

In reply to nufkin:

Haha, now you mention it, you're not! I can just see HW saying those words.

In reply to pneame:

I pinched the quote from here ... https://www.goodreads.com/work/quotes/1816628-pale-blue-dot-a-vision-of-the...

Next book to read.

In reply to aln:

No. I think I'm right in saying that Fred Hoyle was the main physicist behind it. Unfortunately probably better known for being wrong about the Big Bang (he favoured continuous creation in a steady state universe). Sagan's main work was in planetary stuff, but he is now, of course, best known as a great communicator.

In reply to ablackett:

https://carlsagansskateshoes.bandcamp.com

In reply to phja:


Speak for yourself. I'm not made of anything so mundane.

In reply to Robert Durran:


And we should also remember that it was Hoyle who first coined the term 'Big Bang'. On a BBC radio programme in 1949.

In reply to Gordon Stainforth:


Yes. Wasn't he using the phrase to mock the idea?

In reply to Robert Durran:


Or Panspermia (the 'hard' form).

But how were the interstellar seeds created, Fred?

In reply to aln:

But as she herself did not go to Yasgur's farm what did she know? It was just sour grapes.

In reply to felt:


Actually I think the wine produced on the farm was pretty sweet.

D

In reply to gribble:


Snips!?!?! what's snips?

surely it's, "worms and snails and puppy-dogs tails"


Snips!!! Phah!

In reply to ablackett:

There are theories that our own sun has been "re-born" at least once before but possibly twice, so it's been recycled maybe a couple of times already.