Re: ISO detects signal from dark matter in a galaxy similar to the Milky Way (fwd)

Robert J. Bradbury (
Wed, 18 Aug 1999 12:33:31 -0700 (PDT)

> Anders Sandberg <> wrote:

> Larry Klaes <> writes:
> > They have detected in the disk of a galaxy the molecule of hydrogen,
> > considered an important component of the dark matter if it is of the
> > normal, ordinary type. Moreover, the molecular hydrogen is found
> > precisely in the amount needed to fill the missing-mass gap.
> Robert, what do you think of this? Is this bad news for the M-Brains
> as dark matter hypothesis, or have they just found evidence that they
> are sloppy eaters?
Ah, Anders, why don't you put me on the spot!

I've got the papers sitting on my printer and am going to read them over the next few days. The interstellar gas explanation for the missing mass had been made to me by one of the gravitational microlensing astronomers in Jan '98. I think he may have had more knowledge regarding the H2 story than I did.

If the gas does turn out to be as abundant as they argue it would clear up some of the missing mass problem. It would not explain the gravitational microlensing observations or the other evidence very well though. In addition I think they only looked at 2 galaxies. So it is a stretch to extrapolate from that small a sample to the universe.

Robert Freitas has made an argument (to me) that M-brains do not harvest interstellar gas clouds because the mass density is too low to make it profitable. So sloppy eating would not be the source of the gas. However, I don't think this problem (refueling from non-stellar sources) has been given the attention that it deserves. My guess would be that the gas is probably just leftovers from galaxy formation.

Of course, while I would be disappointed if we live in an uninhabited galaxy (meaning intelligent life really is a difficult process for the universe), then the up-side is that all of the material and energy is *ours* for the taking. The pain is that *we* are going to have to come up with the solutions to all those "magic physics" problems ourselves!

The publication of this type of result is one of the reasons to sell M-brains to the engineers before you try to sell it to the scientists (esp. astronomers). The scientists will be able to bury you in reasons and hypothesis why the evidence argues against the existence of M-brains. The engineers will simply look at the blueprints and say, "I can build that." (paraphrasing a song from Chorus Line). The nice thing is that if I'm right about the dismantlement time for Mercury, then we can get the M-brain built before the paper from a scientist that "proves" they don't exist can get back from the reviewers.

My general feeling is that if there are no M-brains out there then we have a situation where
(a) evolution to our level is *very* difficult or
(b) the singularity is universally fatal to civilizations