Why aren't all particles entangled if they originated from the same quantum state?

[ebos]

I was doing some thinking about entanglement and other stuff and a weird thought came up. Since the whole universe, or at least the visible universe, was at one time contained in a very small and homogenous "soup" wouldn't it follow that all the resultant particles that came later would have to be entangled? And if they were what would stop them from still being so? Thanks and use as much metaphorical language and imagery as you want in your answers. Thanks again...

 

[Simon Bridge]

Particles can become disentangled as a result of subsequent interactions.
Entanglement is about the specific statistical relationship between states.

Have you seen the other discussions online, like:
http://functionspace.com/topic/2645...-since-they-all-emerged-from-a-single-entity-

... or more formally,
http://www.sciencedirect.com/science/article/pii/S037026931200994X

 

[ebos]

Well, I thought of that but the particles would only be interacting with particles they were already entangled with, wouldn't they? So yeah, I'll check the links. Thanks.

 

[Simon Bridge]

An interaction between entangled particles may break the entanglement between them.
Mostly it won't matter ... we can demonstrate that two particular particles in the laboratory are not entangled in a particular way we are interested in: this is why we need to deliberately prepare entangled particles for our experiments.