Replies

I'm very comfortable with (the theory) creating heavier and heavier elements at the center of supernova's in today's universe.

Heat, pressure, times, energy levels, and percentage of elements produced work out reasonably well.

But that leaves the original question: Where did today's heavy elements come from, if we can't find the missing supernova's from the first generation stars that created them from hydrogen and helium?

I didn't follow why you think they're aren't enough supernovae. Let me throw out this thought using rough numbers.

A single particle in our tiny sun can experience about 4x10¹⁹ collisions in only a million years, based on a mean free path calculation.

There are about 10⁵⁶ atoms in the sun. In a million years, our sun, by itself, can produce about 4x10⁷⁵ collisions.

In one estimate, the stars in our galaxy contain about 10⁶⁸ atoms. So if you allow for the same rate of collisions that our sun can produce, that gives about 4x10⁸⁷ collisions for our galaxy as a whole in a million years.

If the universe is made of 400 billion galaxies, that gives about 10⁹⁹ collisions without even taking into count the affects of a supernovae.

Now it's true that every collision won't result in fusion. But even if it's only one out of 10¹⁰, there are still 10⁸⁹ collisions remaining without even considering supernovae.

This is enough collisions to replace all the atoms in the known universe (about 10⁸⁰) with heavy nuclei in a million years assuming nothing more than stars like our sun.

This problem is really more complicated than this and I doubt I could come up with a good answer even in multiple sittings, but I thought I'd throw this out there.

You know, I could swear that I had this exact same discussion on FreeRepublic some years ago, and I seem to remember that you yourself were my interlocutor.

I'll be damned if I can find the thread, but I do remember the passage I quoted at the time. Here it is again.

From Chemical Evolution by Stephen F. Mason, p. 47:

Calculations of the relative rates of production of the heavy long-lived radioisotopes provide estimates of the length of time needed to attain the immediate presolar abundance ratios 4.8 billion years ago. The calculated production ratios for ²³²Th/²³⁸U and for ²³⁸U/²³⁵U of 1.80 and 1.42, respectively (Fowler 1978), or of 1.39 and 1.24, respectively (Thielemann et al. 1983), indicate that heavy-element production began in the Galaxy between 12 and 18 billion years ago. These values are wholly independent of other estimates for the age of the universe, based on the relation between the spectral red-shift and the distance of the remote external galaxies, or on the ages of the oldest stars, although the separate estimates are in remarkable agreement (Fowler 1984). The uncertainties of the nuclear cosmochronology estimates are mainly those of the heavy radioisotope production rates, the magnitude of the immediate presolar supernova nucleosynthesis, and the time interval between that event and the condensation of closed solid systems in the solar nebula. The uncertainties of the Hubble red-shift estimates are principally those of the constancy, or the increase or the decrease, of the recession rate of the distant external galaxies.

Those time calculations assume only standard nuclear physics (which dictates, within bounds, the heavy isotope abundances produced by supernovae) and a rate of one supernova per galaxy every 30 years (observed in distant galaxy surveys).

The reason you don't see all the supernova remnants is that they expand and cool to invisibility, get distorted unrecognizably by tidal forces and the interstellar medium, and (when they encounter denser regions of the galaxy) coalesce into stars and planets.

Except under special circumstances, supernova remnants aren't easily recognizable as such for more than a few thousand years. You wouldn't expect to see more than a couple hundred of them in our galaxy, and that is what we see.

You know, I've been puzzling and puzzling over your post, and while most of it doesn't make sense to me, I think I may have come to understand the root of your problem.

You aren't so much concerned with how the heavy elements get created, but with how they got scraped back up together again to form our solar system. Right?

If that is your concern, you may be interested in this calculation I performed almost six years ago on FR.

Here's the executive summary: given a cloud of arbitrary size that has a density as low as any found in the galaxy (one hydrogen molecule per cubic centimeter), how long does it take for the cloud to collapse completely? The answer is 700,000 years. Less than a million years. A cosmological eyeblink. Denser clouds will collapse even faster.

So if you have a supernova going off every 30 years or so, let them spread their heavy nuclei as thinly as you like across the galaxy. Gravity will have no problem collecting them up again in a very short time, whenever it has the chance. All it takes is a local density fluctuation to start the process, and the trace residues of a million supernovae--now evenly spread throughout the galaxy--will condense to form a solar system.

Another suggested Google search term: Jeans Instability