beyond the virial radius, anthropics

There was productive conversation by email today about RR Lyrae stars in deep, multi-epoch visible data among Willman, Zolotov, and myself. Their models (by Governato et al) suggest that there should be a few RR Lyrae detectable in the 100 to 400 kpc range, even in SDSS Stripe 82, if only we can do robust detection below the individual-epoch detection limit. That kind of thing is my bread and butter. Do I feel a collaborative NSF proposal coming on?

In the afternoon, the high-energy physics seminar was by Adam Brown (Princeton) on bubble nucleation in the eternal-inflation (string-theory-inspired) metaverse. It seems that in many natural situations, the most likely bubble to nucleate in our neighborhood (future light cone) could be to a disastrously different vacuum, perhaps even one in which there would be no volume at all (it seems you would just get mashed against the expanding bubble wall). This has implications for our fate, though the standard anthropics (about which we are pretty skeptical at Camp Hogg) protect this theory from making any falsifiable predictions about our past. I used to say that astronomy was only about the past light cone, so perhaps I should be ignoring these subjects?

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