Suppose the cosmologists have it wrong and dark matter really is composed of baryons. It's not like cosmologists have a great track record. Most of their theories have been proven wrong over the past few centuries. Comparing the track record of mathematicians with cosmologists is pretty much night and day. When a mathematician says they have a new discovery it's right, they have cred. A new cosmology theory and $1.50 will buy you a cup of coffee at Starbucks. So why should a computation on the density of baryonic matter in the universe be one of the precious few ideas they actually got right? If dark matter is baryonic then why is it dark? Could it be that it's dark because it's actually dominated by Matrioshka brains? Matrioshka brains are shells which absorb all the light from a star, and all the light which radiates from that shell, and so on until the outer shell is ice cold, let's say for the sake of argument that a typical Matrioshka brain radiates at 2.73 Kelvin so it's in equilibrium with the cosmic background (or maybe the only relevant source of the cosmic background !!)
What if virtually all sentient life evolves in the far outer reaches of a galaxy and galaxies start out as 100% visible matter. As a few Matrioshka brains are born they begin to send out ships and to convert neighboring stars. Within a few hundred million years all stars outside of the core of a galaxy are dark. As galaxies age they "shrink" because the number of visible stars drops, they are being absorbed by the Matrioshka civilizations. This offers an intriguing observational program, watch for vanishing stars at the very edges of the Milky Way.
The interesting implications of this theory are: there is no such thing as time travel, and there is no such thing as FTL travel (faster than light). Either (or both) would mean much faster (essentially instantaneous) conversion of the entire galaxy.
Would there be any hope for us if the first survey ship arrived tomorrow to begin "Matriforming" our solar system? It would certainly take centuries to convert our solar system, but it might only be a few decades before Earth became uninhabitable. Could we fight back, would they absorb us into the collective before we had a chance to fight back? Makes for an intriguing plot.
Comments (7)
Dark matter baryonic? I can buyMatrioshka shells and Dyson spheres first? What is your evidence?
I think the claim that dark matter is a strange new mysterious form of matter is so extraordinary that it violates Occam's Razor. Extraordinary claims required extraordinary evidence and so far the cosmologists have offered virtually none. Did you read the link in my post?
http://www.astro.princeton.edu/~dns/MAP/Bahcall/node3.html
> I think the claim that dark matter is a strange> new mysterious form of matter is so > extraordinary that it violates Occam’s Razor.
I largely agree with this. I'm not up on current theories of dark matter, but is there any good reason for not just thinking that there is a lot more normal stuff hanging around, being dark, and thus not getting spotted, than inventing a whole new form of matter?
Colum
>What if virtually all sentient life evolves in the> far outer reaches of a galaxy and galaxies > start out as 100% visible matter. As a few > Matrioshka brains are born they begin to > send out ships and to convert neighboring > stars. So the aliens aren't just hiding, they are sneaking up on us?
Actually, if engineering on this scale is possible (it might not be, but lets say it is) then this is a good explaination for the fermi paradox.
This would mean our galaxy is actually much bigger than we percieve it to be though, right? Most of it having been swallowed up already?
The interesting thing about this, is if you had predicted this years ago, if you had said "I think civilisations build dyson spheres that hide their star systems from us, and have been gradually putting out the lights in the sky for aeons" people would expect you to make testable predictions. The obvious testable prediction to make is that the amount of matter predicted by gravitational models is going to be larger than the amount we can actually see. Which is exactly what we have today with dark matter. (okay, that alone wouldn't be proof, but it would be a first hurdle for the theory).
Colum
> The interesting implications of this theory> are: there is no such thing as time travel, > and there is no such thing as FTL travel >(faster than light). Alas, relativity (+causality) already largely gives us this. I wish it were otherwise, but there it is. The interesting implication of your theory is that the galaxy should be 'heavier' than we expect, and it is!
Colum
>This offers an intriguing observational>program, watch for vanishing stars at the very >edges of the Milky Way. Given stellar distances, you might have to watch for a long time. Right now a colony ship could be setting out a sub-light speeds, it would take god-knows how long to crawl to the next star (assuming star is fairly near, and they have something like orion/promethus, maybe 100 years. But that assumes they are in a hurry. If you're a civilisation with the ability to make matrioska shells, maybe you are also quite happy to mosey along at much slower speeds, and take hundreds, even thousands of years to get to where you are going. Why not?) When they do turn out the lights, it will take thousands of years for the event to be seen from earth (unless they happen to be very close buy, in which case, as you observe, we're pretty much boned.)
Colum
Good idea. Interesting question, I just thought of it as well. If it is Matrioshka brains, they also must be light-bending for us to be able to see through them.