The Cal-tech lecture hall was quickly filling up for the lunchtime talk. The audience had the typical tired and disheveled group of graduate students... most bringing in food of some sort. One sleepy looking young woman shuffled in wearing dirty and beaten bunny slippers, complete with tattered floppy ears. However, in addition to the usual group of tired astronomy grad students, some of the senior professors quietly slipped in and, in general, chose seats near the back.

The title of the talk was intriguing; "New Developments in the Understanding of the Nature of Dark Matter", but it was the nature of the speaker that was drawing the large crowd to the lecture hall. Typically the lunchtime talks were short, but educational synopsies of recent results from various professors studies. Todays speaker, Dr. Allen, was known for his flair for the dramatic, and his habit of releasing his most impressive results in informal forums such as this.

For the past 16 months Dr. Allen had been behaving oddly. First, he had another professor take over all his classes halfway through the semester, then he stopped holding his usual office hours. One by one the four graduate students he advised stopped showing up for classes and virtually disappeared from the department. When questioned about what was keeping them so busy his students became uncomfortable and evasive.

All indications were that Dr. Allen was onto something big, although some of the more cynical students thought he may just be abusing the freedom his tenure gave him. The talk would likely be an event of some sort... and everyone in the department could sense it.

The lecture hall filled and the sounds of rustling paper filled the room as the audience started their lunches. Noon came and went and a few in the audience became nervous that Dr. Allen was not going to appear. However, at 12:05, Dr. Allen came quickly shuffling in, in his typical frantic fashion carrying a manilla folder with transparencies nearly spilling out of it.

It was a wide spread joke that Dr. Allen had to spend more on his wardrobe than any other professor in the department, since 1970's vintage suits had to cost a pretty penny in 2008.

He smiled shakily at the crowd and organized his transparencies clumsily. He refused to use the the projector that simply plugged into a laptop for his talks, saying only that he didnt trust it, so an old transparency projector was kept on hand for his talks.

After a few moments of awkward fumbling, his thin stack of transparencies seemed to finally be in an order that suited him. Grinning widely he finally gazed over the audience. "Ummm, sorry about being late- I had problems with my tie..." He reached up and fidgeted with what was obviously a clip on tie.

"Ahem, well, lets get started!" He slapped his hands together and seemed startled at how loud it sounded in the large room...

"Well, first this talk is on some recent studies my students and I have done on dark matter-" He put up the title slide, his four graduate students names preceeded his on the credits, a practice of his that endeared him to the students in the audience.

"I am afraid this work has kept them working long hours lately, but as you will see the results are likely worth it."

Some in the audience listened intently. Others watched blankly while eating.

"First lets start with a little history. It has long been accepted that there exists something that has come to be called 'dark matter', how much of this unseen matter exists is not known but it is known that it makes up a large percentage of the universe.

The first observed indications of its existence were in distant galaxies that rotated faster than their apparent mass allowed. Other observations hinted that there must be some large amount of unseen matter that was exerting a gravitational force on 'normal' matter.

Theorists have no end of ideas for what this dark matter could be; Failed stars, MACHOs, WIMPs and supersymmetric particles have all been suggested as possibilities- none have been definitively proven."

Dr. Allen nervously sipped at his glass of water. It dribbled onto his tie and he grimaced and unclipped it, setting it on the table. A few in the audience giggled, but he seemed oblivious as he dabbed the tie with a napkin.
Finally he grabbed a transparency and put it up...

"About three years ago radio observations led to the discovery of what came to be termed a 'dark matter galaxy'- a cloud of hydrogen rotating like a galaxy and held together by gravitation from some unseen matter. The estimated mass required to hold this 'galaxy' together was some 10^8 solar masses, yet when optical and near IR scopes observed this region nothing was visible. This observation spurred a search for more 'dark matter galaxies', and since then several dozen more have been found. All of them have few or no optical counterparts.

It has lately become hard to get optical telescope time to look at these 'dark galaxies', since papers entitled 'We Didn't See Anything Either' are hard to get published!"

He laughed a little too long at his joke...

"Umm, well anyway... We decided to make use of the Spitzer IR space telescope to do a survey of these anomalous galaxies. The Spitzer space telescope offers unique capabilities- it looks at longer IR wavelengths, 3-200 microns, that are difficult or impossible to observe from the Earth's surface. The first observations were umm, interesting to say the least."

He shuffled through the tranparencies nervously.

"This is a 'picture' of the first dark matter galaxy taken by the Hubble"

He put up a picture that had numerous distant galaxies and a giant ellipse drawn on it- seemingly encircling nothing.

"The ellipse denotes the extent of the galaxy observed via radio observations. As you can see there are no optical indications of this galaxy. "

Most had seen the picture before and were not terribly surprised... It was an interesting enigma, but old news.

"And this is the image taken by the Spitzer telescope 18 months ago. " He place another slide on the projector on top of the Hubble picture. Now inside the drawn ellipse appeared a disk of bright points and clouds.

"This is a composite of exposures taken at wavelengths between 5 and 20 microns- as you can see it appears that this is a somewhat spiral galaxy."

All thoughts of lunch seemed to be forgotten as the once invisible was revealed for the first time.

"We have observed about a dozen of these 'dark matter galaxies' and every time the results have been similar- where nothing is seen in the optical we see entire galaxies when we look at the IR images from the Spitzer. The peak of the emission from these galaxies seems to be at roughly 10 microns wavelength."

The room was silent- this was BIG!

"Some theoretical models could partially predict this behavior for dark matter- they all required massive amounts of non-baryonic matter, we tried to apply these models to our observations but none of them completely fit with the data, then we had a lucky break.

Three and a half months ago we observed a supernova in the first of these 'dark galaxies' discovered."

The audience muttered, stunned.

"How could there be a supernova where there are no stars? The light curve from this supernova was identical to those observed countless times before in 'normal' galaxies."

He put up a before and after picture of the spitzer image of the dark galaxy- the after picture showed a brilliant point flaring in an arm of the spiral.

"I want to emphasize that the ONLY cosmic explosions exhibiting this light curve have all been supernovae- NO theoretical models for exotic explanations for dark matter predict this kind of behavior. So how do we explain all these contradictory observations?"

The audience was listening intently, he smiled nervously.

"We followed up our observations with intensive observations of the IR spectra from these galaxies- we found that the spectra were compatible with blackbody radiation from objects at a temperature between 200 and 500 degrees Kelvin, The predominant 'temperature' seems to be around 300 degrees Kelvin. This temperature is similar to what you may expect from a body that is a small failed star- several jupiter masses... but a galaxy populated by only superjovian mass objects is hard to imagine- based on what we know it is a statistical impossibility! It also does not explain the observation of a supernova where no star has been observed."

"The interesting fact is that the 'temperature' of most of the objects that make up these galaxies is a balmy 300+ degrees Kelvin- perfect for liquid water. What are we to make of this?"

He sipped at his water again, grinning and looking around- his demeanor became calmer, he fiddled with his tie on the desk.

"In the 1960's there was a Russian astronomer named Nikolai Kardashev... He liked to think big."

He sipped his drink as the audience seemed to be confused by his change of subject.

"Kardashev speculated about how civilizations might develop, he looked at humanity's exponential growth and extrapolated it. He came up with a classification system for possible civilizations.

First there is a 'Type I' civilization- this is a civilization that utilizes all the power available to a single planet, approximately 10^16 to 10^17 Watts... We are rapidly becoming a type I civilization.

Next on his scale is the Type II civilization- this civilization harnesses the all the power of a single star. Roughly 10^26 Watts... Dr. Freeman Dyson suggested ways of doing this with what have become known as 'Dyson Spheres'. Shells built around a star to collect all power it releases- their interior surfaces habitable... seems fantastic doesnt it?

Finally, Kardashev described a 'Type III' civilization- this civilization harnesses the power output of an entire galaxy- 10^36 Watts."

He grinned widely and looked at his audience.

"Now what would a galaxy that was home to a Type III civilization look like? It would be dark... all or most of its stars surrounded by shells collecting their power and providing nearly limitless space for growth. The radii of the shells would be tailored to the star so that the interior was at the habitable-zone. The shell would be at approximately a nice 300 degrees Kelvin- its exterior radiating into space at that temperature. These stars would eventually die, sometimes violently. But to outsiders a TYPE III galaxy would appear dark, and indeed look like what we are seeing in every way...

This also addresses the 'Fermi Paradox'- there is intelligent life out there, they are just hidden- I submit that these 'dark galaxies' are proof of type III civilizations, and that they show us how much is possible.

We apparently have a long road ahead.... "

Dr. Allen became awkward again...

"Umm any questions?"

The room remained silent- his theory, as fantastic as it was, fit all the facts more than any other...