Comments on: New Hubble Release: Dramatic Galaxy Collision

By: Jon Hanford

Jon Hanford — Fri, 16 Oct 2009 14:40:17 +0000

Perhaps those Boltzmann brains could be set to work on Tegmark's mathematical universe hypothesis ( http://en.wikipedia.org/wiki/Mathematical_universe_hypothesis )

By: DrFlimmer

DrFlimmer — Thu, 15 Oct 2009 20:45:47 +0000

Reminds me of the last chapter in Phil Plait's book "Death from the sky". In it he deals exactly with these mind-boggling numbers and the "dark" things that may happen. Somehow, I prefer the shiny situation of today….

By: Lawrence B. Crowell

Lawrence B. Crowell — Thu, 15 Oct 2009 19:59:54 +0000

In about 10^{16} years the last of the stars will have winked out, and even by 10^{12} years the night sky in the Androway galaxy will be pretty dark. Things will grind down from there. In about 10^{40} years any region of the universe bounded by the cosmological horizon will consist of one large black hole, and little else. Those will eventually quantum evaporate away by the year 10^{110} . The unvierse will appear as a perfect de Sitter vacuum solution, almost. The cosmological horizon will quantum decay and over an infinite (near infinite?) time frame receed off to infinity. The universe will end up as a Minkowski spacetime or a pure void.

However, not all is doom! During that long dark time the Hawking radiation from the cosmological horizon has a finite probability for giving rise to "Boltzmann brains." These are odd entities, but in the year 10^{10^{10^…}}} a random assembly of such quantum states could come about to form a processor (Boltzmann brain), which could spend its existence computing out all possible mathematics.

Lawrence B. Crowell

By: DrFlimmer

DrFlimmer — Thu, 15 Oct 2009 18:40:52 +0000

Such observers might also notice a much higher frequency of red dwarf stars and collapsed stellar remnants than we observe.

[deep voice on] And when this happens, the ultimate doom is at hand. Prepare for the last day to come – it may be the longest day and a far longer night. [deep voice off]

By: Lawrence B. Crowell

Lawrence B. Crowell — Thu, 15 Oct 2009 18:19:44 +0000

Yep, and these hypergalaxies will end up as islands where any observer in them will see other galaxies redshift away and disappear. It might only take 20 billion years for that to happen. Such observers might also notice a much higher frequency of red dwarf stars and collapsed stellar remnants than we observe.

By: Jon Hanford

Jon Hanford — Thu, 15 Oct 2009 15:39:14 +0000

@LBC, It does seem that most galaxy clusters with sufficient mass will eventually evolve to have a supermassive galaxy in its midst. Some clusters (like the nearby Coma Cluster) have two of these monster size galaxies that have yet to coalesce into an even larger supergalaxy. Definitely entropy in action.

Our own Local Group is probably best described as just that, a rather small group of galaxies. But not forever. Observations show that our Local Group is falling towards the massive Virgo Cluster. Whatever becomes of the Milkomeda Galaxy (Andromeda-Milky Way merger) it will eventually be gobbled up by some supergiant galaxy in the Virgo Cluster ( say….M 87 ).

By: Lawrence B. Crowell

Lawrence B. Crowell — Thu, 15 Oct 2009 03:11:28 +0000

I presume galaxy clusters end up being dominated by a single large elliptical galaxy formed from the coalescence of galaxies. Our galaxy is a bit of a galaxy cannibal already, and in about 2 billion years will with Andromeda engage in the sort of tango seen in the numerical simulations. The local group might end up with one large elliptical galaxy with a few dwarf galaxies around it.

With gravity, entropy increases with clumping. The accumulation of galaxies into large ellipticals at least makes thermodynamic sence.

By: DrFlimmer

DrFlimmer — Tue, 13 Oct 2009 17:59:32 +0000

Thanks Jon, for the numbers. They give a small feeling of the scales we are dealing with here.

Amazing!

By: Jon Hanford

Jon Hanford — Tue, 13 Oct 2009 14:31:25 +0000

Interesting resemblance to the "Antennae" galaxy (NGC 4038-39 = Arp 244). In the linked paper, the researchers mention that this system represents a larger, more distant counterpart to the "Antennae". For a sense of scale, the bluish starburst region to the upper left of the nucleus is reported to be 60% the size of the LMC (~3.2 kpc) but two times brighter! And further, the paper mentions that ~7% of the 100 Super Star Clusters discovered have luminosities exceeding that of 30 Doradus (the Tarantula Nebula = NGC 2070). So a few of those star clusters in the small starburst region near the nucleus are probably brighter than 30 Dor! Beautiful Hubble image of a distant interacting luminous infrared galaxy.