Half Life

Rubecula

All radioactive elements have a half life.

But do none radioactive elements also have (a very long) half life?

Will everything one day break down into hydrogen?

If it does, will this be the possible source of renewal for the universe? Or will even Hydrogen break down to something less?

FISMA

True, if an element or its isotope is radioactive, it will have a half life.

Many radioactive isotopes have very long half lives.

Not all elements are radioactive. Thus, they have no half life.

Many elements have isotope(s) that are unstable and will radioactively decay over time.

For example, an atom of H does not have a half life. Neither does an atom of He.

H (proton + electron) comes in two flavors: Deuterium (proton-neutron + electron) and Tritium (proton -2neutrons + electron).

H and D do not have half lives, T does. T undergoes Beta Negative Decay and has a half life of 12.33yr.

Nuclei that are neutron rich, like to undergo Beta Negative decay. Like wise nuclei that are proton rich prefer Beta Positive decay.

So, not everything breaks down via radioactive decay into Hydrogen.

Here is a decay series, specifically for Uranium 235


Here's a great site for nice and concise Physics. They layout the concepts like a flowchart and despite the high level material, they do a great job in helping people understand.


http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

ray giraffe

Rubecula wrote: »

But do none radioactive elements also have (a very long) half life?

Will everything one day break down into hydrogen?

If it does, will this be the possible source of renewal for the universe? Or will even Hydrogen break down to something less?

Protons might have a half life of around 10^36 years!

3×10^43 years—highest possible time for all protons and neutrons in the observable universe to decay, if proton decay occurs.


Even if there's no proton decay everything will turn to iron:

10^1500 years—the estimated time until all matter decays to 56Fe (if the proton does not decay).


And then neutrons and singularities:

10^(10^76) years :eek: —high estimate for the time until all matter collapses into neutron stars or black holes, assuming no proton decay.


http://en.wikipedia.org/wiki/Proton_decay

http://en.wikipedia.org/wiki/1_E19_s_and_more