'Edge' of the Universe

It doesn't matter who is determining a half life but whether it is done correctly. The radioisotope must be purified such that no other radioisotopes are present. In reality, this is impossible to achieve. For example, "pure" plutonium-239 will in reality contain two dozen other radioactive isotopes. They will be present in "trace" quantities.

The real issue with half lives is whether radioactive decay comes from within or outside of the nucleus. IMHO, the nature of the decay is dependent on the nucleus but when it decays depends upon the chance arrival of an outside entity which collides with the nucleus. Scientists refer to "spontaneous fission" but this is an implicit admission that "we don't know what causes fission".

An atomic bomb works because the environment outside of each Pu-239 nucleus is changed. Any action, geometric or chemical, which increases the neutron flux, will drastically shorten the half life. For instance, take a plastic cube with the top open. Drop in, one at a time, plutonium beads (tiny balls). With a cube geometry, when the addition of plutonium beads reaches a mass of about 600 grams, the plutonium will go critical. Instead of a half life of 24,360 years, it will have a new half life of minutes.

Dissolve plutonium in nitric acid so that its concentration is just short of precipitation. Pour the plutonium nitrate water solution into the plastic cube. When the total plutonium amount reaches about 240 grams, the plutonium will go critical. It takes less plutonium because the water molecules reflect neutrons and lower their velocity to an "ideal" speed. Use heavy water (deuterium oxide) and it will take a lot less plutonium than 240 grams. These facts were learned by mistake and the persons involved became extremely ill or died. Don't attempt it.

In essence, half lives can be shortened by changing the environment external to each radioactive nucleus. Conventional half lives are measured at the conditions on the surface of the Earth, where very little radioactivity is present. Consider what might be going on at the interface of the Earth's core with the Earth's mantle....

Gregg Wilson

Well I hope plutonium is a controled substance-I wouldn't want to find that in my bowl of beans. My question is about critical mass and the halflife tables. I know they are calculated to aid people who need that kind of info and have only a hint of reality. The thing is the proton is not as stable as it is assumed to be by modelers. The proton is made in manmade machines and is unmade too. So environment is the key to making the tables more in tune with real things. I want to know more about the halflife of the proton changes when it is put in other environments. Do you know?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />Hi Gregg, I don't want to go into some of areas you bringing up, but, the half life of the proton being 10E32 years is one detail I would like to know more about because I think this a false belief. If the proton is put into the proper environment its halflife would be a few nanoseconds tops. What I want to know is how and who determines the halflife of anything and if it is affected by the environment in which it exists? This detail relates to fusion and fission and lots of other stuff.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Jim

what is this "proper enviroment" you speak of ? and it is known from plasma physics that the proton and the electron are the longest living particles by far that there is.

[Originally posted by Jim]The proton is made in manmade machines and is unmade too. So environment is the key to making the tables more in tune with real things. I want to know more about the halflife of the proton changes when it is put in other environments. Do you kno<hr noshade size="1">

No positive evidence for the lifespan of the proton has been established. Given an infinite dimension of scale, it may have a lifespan. But, from our position on the dimension of scale, it appears to be permanent. In extreme contrast, a free neutron decays to a proton and an electron in about 10-12 minutes.

Firing protons at nuclei, with a mass accelerator, has disassembled nuclei but not protons.

Gregg Wilson

Protons are built in nanoseconds or less in particle accelerators-are they not? And they are transformed in to the tangled wed of subatomic particles in the same time scale. So, how can anyone say they are stable in all environments? The whole model here is a mess that needs fixing. And yet even though this is fact no body wants to fix the model unless the funding process is altered. Some people make a living off this stupidity.

[Gregg] "We seem to have a problem of semantics here, or is it differing viewpoints on the concept: cause and effect?"

[LB] "Neither one, I'm pretty sure. "

After thinking about this for a while I see I was wrong. I now believe the problem is semantics. I have no problem thinking in terms of an attractive force between two masses because I know that the ultimate cause of that attraction is a push from a third mass, the graviton.

But in an environment such as this discussion group many people either don't know about pushing gravity or don't have a clear image in their heads about how it works. Nor how it can lead to the existence of other (also indirect) attractive and repulsive effects/forces such as electricity and magnetism.

I need to try to adjust my vocabulary to avoid this ambiguity.

Thanks,
LB