#missing mass

The Day Zimmer Lost Religion

The first Sunday I missed Mass on purpose I waited all day for Christ to climb down Like a wiry flyweight from the cross and Club me on my irreverent teeth, to wade into My blasphemous gut and drop me like a Red hot thurible, the devil roaring in Reserved seats until he got the hiccups. It was a long cold way from the old days When cassocked and surpliced I mumbled Latin At the old priest and rang his obscure bell. A long way from the dirty wind that blew The soot like venial sins across the schoolyard Where God reigned as a threatening, One-eyed triangle high in the fleecy sky. The first Sunday I missed Mass on purpose I waited all day for Christ to climb down Like the playground bully, the cuts and mice Upon his face agleam, and pound me Till my irreligious tongue hung out. But of course He never came, knowing that I was grown up and ready for Him now.

Sterrenkundestudent ontdekt grote wolk ‘waterstofsneeuw’, een deel van de ontbrekende materie

Impressie van een koude gaswolk, die door getijdewerking uiteen is gerukt. Credit: University of Sydney Dat slechts 5% van alle massaenergie in het heelal gewone, ‘baryonische’ materie is en de rest bestaat uit donkere energie en materie, is al lang bekend. Ook is bekend dat van die schamele 5% van protonen, neutronen, elektronen en andere elementaire deeltjes, waaruit sterren, planeten, gas- en…

Sterrenkundestudent ontdekt grote wolk ‘waterstofsneeuw’, een deel van de ontbrekende materie

Impressie van een koude gaswolk, die door getijdewerking uiteen is gerukt. Credit: University of Sydney Dat slechts 5% van alle massaenergie in het heelal gewone, ‘baryonische’ materie is en de rest bestaat uit donkere energie en materie, is al lang bekend. Ook is bekend dat van die schamele 5% van protonen, neutronen, elektronen en andere elementaire deeltjes, waaruit sterren, planeten, gas- en…

Waar is de ontbrekende materie van het heelal? In ieder geval niet in de halo’s rondom sterrenstelsels

Credit: ESA/XMM-Newton; J-T. Li (University of Michigan, USA); Sloan Digital Sky Survey (SDSS)

Als je alleen naar de materie in het heelal kijkt en de (donkere) energie buiten beschouwing laat is pakweg 85% van die materie de mysterieuze donkere materie, de rest (15%) is gewone materie, ook wel baryonische materie genoemd. Die gewone materie zijn de sterren, planeten, gas- en stofwolken, alles…

Waar is de ontbrekende materie van het heelal? In ieder geval niet in de halo’s rondom sterrenstelsels

Credit: ESA/XMM-Newton; J-T. Li (University of Michigan, USA); Sloan Digital Sky Survey (SDSS)

Als je alleen naar de materie in het heelal kijkt en de (donkere) energie buiten beschouwing laat is pakweg 85% van die materie de mysterieuze donkere materie, de rest (15%) is gewone materie, ook wel baryonische materie genoemd. Die gewone materie zijn de sterren, planeten, gas- en stofwolken, alles…

Dark Matter AKA Missing Mass related to Dark Energy

Dark Matter is one of those concepts in science fiction where an author hears the name and then their imagination runs away with them and they never look back. Unfortunately, this leaves anyone who knows anything about science and astronomy completely thrown out of suspension of disbelief. Dark matter is actually a very simple concept. Dark…

The gray goo scenario is the existential risk constituted by the runaway exponential reproduction of self-replicating nanobots. There are many variations on this theme: the nanobots might convert organic material into more nanobots, wiping out life directly, or the nanobots might convert some inorganic material into so many nanobots that life is suffocated under a pervasive and inescapable blanket of gray goo (I suppose this might also be called the "gray ooze" scenario, but that would eliminate the quasi-poetic alliteration). The reader will recognize a classic "sorcerer's apprentice" theme in the gray goo scenario.

Gray goo is not only a potential threat to terrestrial life, it could be a threat to the whole of the universe. A swarm of self-replicating nanobots loose in the cosmos, able to cover the distances between stars, and possibly also the distance between galaxies and galactic clusters, could smother the whole of the universe under suffocating gray goo. While this gray goo would be ordinary baryonic matter, and not something exotic, it would not radiate energy like stars, so it would not be easy to detect at a distance except for its mass.

The idea of an enormous amount of mass that is not easily visible is actually a familiar problem in cosmology, called the missing mass problem. Missing mass in the cosmos reveals itself in a beautifully simple and elegant manner: the spiral galaxies we can see rotate more rapidly than they should rotate given the matter represented by the (visible) stars of the galaxy. This seems to be true of all galaxies, hence the missing mass problem. Today the missing mass is accounted for by "dark matter," but one must understand that "dark matter" is just a cipher that means, "whatever that is out there that accounts for galaxies spinning as fast as they do (as well as other indications of missing mass)."

One (perhaps bizarre) way to account for the missing mass of the cosmos would be a universal-scale gray goo catastrophe. Galaxies may be heavier than they appear because much of their mass has been transformed into gray goo. Only a single advanced civilization with a modest capacity for interstellar travel would be sufficient to unleash gray goo on a galactic scale by means of Bracewell probes (also called Von Neumann probes, and sometimes also Bracewell-Von Neumann probes). Indeed, galactic colonization models that rely upon sentient communities are subject to endless second-guessing as we speculate on the possible motives of a peer civilization, but something like the gray goo scenario is more like a pandemic than a diaspora, and its spread through the universe would be quantifiable with a greater degree of precision than the expansion of a peer civilization into the universe.

While I do not myself advocate the view I am here presenting, it would be an almost startlingly elegant solution to both the Fermi paradox and the missing mass problem. Elegant though the solution would be, we can be confident that there has been no universal gray goo scenario, since we are here. A gray goo catastrophe that was so pervasive as to weigh down all visible spiral galaxies with mass we cannot detect at a distance would not have spared us. Our existence is proof that a universal gray goo scenario has not occurred. This in itself is interesting, as if it is argued that some kind of runaway replication catastrophe scenario is inevitable to industrial-technological civilization, we can ask of gray goo what Fermi asked of extraterrestrials: where is it?

A more exotic formulation of the idea above would involve gray goo fashioned from computronium (i.e., programmable matter), and, specifically, computronium that could intelligently mask its presence and thus remain dark under any and all circumstances, meaning that a supercivilization that had grown to encompass an entire galaxy could effectively remain invisible and therefore undetected. A failed supercivilization might leave this as a relic, or an ongoing supercivilization might conduct megaengineering on a galactic scale even while denying any observer direct evidence of the presence of itself. Once our scenario gets this elaborate, we can work around the fact that we are here, and posit that the computronium gray goo had been programmed to avoid inhabited systems, so that it only self-replicated from sterile matter. At this point we have extended our scenario far beyond what the principle of parsimony can sustain.

Note added 05 December 2014: After posting the above, Henning Rogge has pointed out to me (in a comment on Google+) that it is impossible that gray goo could be taken for dark matter: "...more than half the mass of a galaxy is not in stars but in form of dust and gas between the stars. Does it create light by nuclear fusion? No... can we see it? HELL YES! Its simple thermodynamics. If it's matter and it absorbs light, it will heat up until it starts giving away as much light energy than it receives. Simple black body radiation."