ASTRO 142 Chapter Notes - Chapter 16: Higgs Boson, False Vacuum, Particle Horizon
Document Summary
Surface beyond which we cannot see: horizon. Any two objects in the universe can be casually connected and influence one another if the(cid:455) are (cid:449)ithi(cid:374) o(cid:374)e a(cid:374)other"s parti(cid:272)le horizon: changes with time. Hubble length and horizon are used interchangeably for things such as matter perturbations during the epoch of galaxy formation, but not the very early universe: particle horizon affected by the general relativity bending of light. Particle horizon contains all of the universe observable to us. Regions separated by more than 1 degree cannot have been in casual contact with each other around the time of recombination. Is e(cid:454)tre(cid:373)el(cid:455) (cid:272)lose to 1, a(cid:374)d e(cid:448)e(cid:374) more so as you approach the time of the big bang. If had (cid:271)ee(cid:374) a(cid:271)o(cid:448)e the u(cid:374)it(cid:455) earl(cid:455) i(cid:374) the (cid:271)ig (cid:271)a(cid:374)g, the u(cid:374)i(cid:448)erse (cid:449)ould (cid:272)ollapse quickly. If would have been below the unity, it would be strongly open such that it would expand too rapidly and the average density would be too low.