Originally posted by woadman Yes folks--at any time a Phase Transition can do away with us all ! But do we know if space/time is subject to such a thing? Like water turning into ice ?
That's physics beyond the standard model. I don't know if there are any string theory derived models which have that. But note the following points:
1) It's never happened in the 13.8 billion years of the universe's history since the electro-weak epoch.
2) L.H.C. won't do that, if it could then any higher energy collision could and they happen regularly on Earth - occasionally a cosmic ray comes along (at least daily) with the same energy as a cricket ball doing 60 miles an hour (LHC's protons have about the same energy as a flea). It hasn't ended the universe yet so LHC won't.
3) If it did happen the phase transition boundary would pass us at, or just under, the speed of light and all the physics that causes electrical impulses in our body would stop working. We wouldn't feel a thing.
Originally posted by woadman But if the Phase Transition started far away, we could see it coming for many years. (at the speed of light)..wouldn't we know our fate ?
If the phase boundary moves at the speed of light then we won't see it coming as it's moving at the same speed as the signal. If it's already happened and moving at less than the speed of light then it is further away than any galaxy we can see and won't arrive for a billion or so years. If the chances of it happening anywhere in the universe are more or less equal then the chances of it being close enough to be a worry before humans become extinct anyway are so remote it's still not worth worrying about.
It's believed that at the very beginning of the big bang--it was phase transition that CAUSED the great expansion that then allowed atoms to form.
Anyway, once gravitational WAVES are found, then the discovery of gravitons should be easier.