Jotaf, your concerns are specifically addressed in the recent LHC report.
In reverse order,
3) Bubbles of vacuum decay expanding at the speed of light are a problem in any reference frame, so they are well constrained by astronomical observations. Most cosmic rays are coming inwards, so many of the particles would have to escape through the planet, neutron star, etc. Anything with an electric or magnetic charge would be stopped (magnetic charges come on monopoles). This means everything but neutral black holes can be immediately bounded by
astronomical evide... (read more)
Jotaf, your concerns are specifically addressed in the recent LHC report.
In reverse order,
3) Bubbles of vacuum decay expanding at the speed of light are a problem in any reference frame, so they are well constrained by astronomical observations. Most cosmic rays are coming inwards, so many of the particles would have to escape through the planet, neutron star, etc. Anything with an electric or magnetic charge would be stopped (magnetic charges come on monopoles). This means everything but neutral black holes can be immediately bounded by astronomical evide... (read more)