WI no natural radioactivity?

[Paul Leyland]

Suppose that all nuclei were either effectively stable (half lives over
a trillion years, so uranium, thorium, neptunium and plutonium would be
stable to alpha and beta decay but not to fission whether spontaneous or
induced) or very unstable (less than a microsecond) but the rest of
physics and chemistry continues as now. What would be the effect on
modern history?

We would still know about protons, neutrons and electrons, we would have
X-rays, microelectronics and particle accelerators. Einstein would still
conclude E=mc^2 and we would know that fission or fusion could produce
energy. The stars would still generate energy as they do now.

What we would not have are easy fission reactors, nuclear medicine, and
carbon dating or any other kind of isotopic dating for that matter. What
else?

WWII and afterwards would clearly be very different. The US would have
much more money and scientists to use on other than the Manhattan
project. Again, what else would be different?

[Dimensional Traveler]

The entire planet's history would be wildly different. Radioactive
decay is part of what keeps the core of the planet hot. It would affect
plate tectonics, the proportions of metals in the crust and more. There
is some evidence that the sudden proliferation of species around the
time hominids started evolving, leading to Homo Sapiens, occurred around
the time our solar system entered a supernova debris field containing a
radioactive isotope of iron in sufficient quantities for it to show up
in Earth's geologic records.

--
I've done good in this world. Now I'm tired and just want to be a cranky
dirty old man.

[Paul Leyland]

Understood.

I was setting up a hypothetical situation which assumed the terrestrial
environment would be otherwise unchanged. Elemental abundances from SN
explosions would be different, for instance, as would the lack of
heating from Al-26 decay change planetary formation.

Let's assume for the model that radioactive decay changes continue
through the same pathways and at different rates but have the same
cosmological, geological, etc consequences as in the Universe in which
we presently live. If you wish, and if it makes it easier to comprehend,
let us assume that the laws of physics magically changed in 1880.

Confession: many years ago I read a SF work in which such a change was
introduced by an advanced technology through an application of Clarke's
3rd Law. I am now interested in finding out what others can work out in
this scenario.

Incidentally, a set of the laws of physics in which the weak interaction
is exceedingly weak can still produce a chemically and physically
interesting universe. The Big Bang produces primarily protons and
neutrons, with a fair smattering of He-4. The neutrons do not decay and
those which do not fuse with protons to produce deuterium form dark
matter. Stars generate energy from DD fusion to He-4 and helium burning
continues when the core temperature rises high enough, and so. Elements
as far as Z=32 or so are stable. I can dig up references if anyone is
sufficiently interested.

[Dimensional Traveler]

S.M. Stirling's 'Dies the Fire' universe, by chance?

> Incidentally, a set of the laws of physics in which the weak interaction
> is exceedingly weak can still produce a chemically and physically
> interesting universe. The Big Bang produces primarily protons and
> neutrons, with a fair smattering of He-4. The neutrons do not decay and
> those which do not fuse with protons to produce deuterium form dark
> matter. Stars generate energy from DD fusion to He-4 and helium burning
> continues when the core temperature rises high enough, and so. Elements
> as far as Z=32 or so are stable.  I can dig up references if anyone is
> sufficiently interested.
>

[dama...@gmail.com]

In such a case, life, assuming it began, would probably still be single celled organisms. Without the presence of radioactive potassium (0.012% of all potassium) to induce changes in DNA, the rate of mutation is severely decreased. And in case anyone is wondering, yes, bananas are radioactive.

Dean