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Home » Dave’s DiegesesMarch 2005 » Dave’s Diegesis: Dark Matters

Dave’s Diegesis: Dark Matters

For now we see through a glass, darkly, but then face to face: now I know in part; but then shall I know even as also I am known.
1 Corinthians xiii. 12.

Earlier this year astronomers found evidence of a dark matter galaxy. At first it was thought to be a mass of hydrogen atoms, but on closer observation it was much more massive and fast moving to be merely hydrogen. (Incidentally, hydrogen is the only element whose isotopes have different names. The simplest and most abundant form of hydrogen is known as protium. Deuterium, also called heavy hydrogen, has a nucleus of a proton and an neutron. Finally, tritium is a radioactive form of hydrogen with a nucleus of a proton and two neutrons and a half-life of 12 1/4 years.)

Although originally detected in 2000, it has taken five years to rule out other possible explanations for this unseen matter. The dark matter galaxy was named VIRGOHI21. Dark matter makes up approximately 85% of the mass in the universe, and the existing mass matters because it will ultimately determine the fate of the cosmos.

I often discuss astronomy with my teammates. They’re always telling me that I’m really into space and that they like that I’m out there. I give them constant updates about such pressing issues as the cosmological constant. I mean, everyone wants to know if the end of the cosmos will be the Big Crunch, the Big Rip, or the Big Chill, right? Just yesterday I was explaining to Millar the Friedman equation:


If we knew the value of Omega (Ω), we’d know how it all ends. If the average density of matter is greater than the critical density, then the gravity attracting all extant matter would reverse the expansion of the universe and cause the Big Crunch. If this density is below the critical density, and recent evidence of the increasing speed of the universe expanding bears out over the course of the next 2x1010 years, then the Big Rip comes into play. Finally, if the average density is equal to the critical density, then the universe expands forever at a constant rate until everything is the same undifferentiated temperature.

Kevin was blown away, and then mentioned how he’d prefer the Big Chill because of the swinging. I went back to the whiteboard and tried to show him the laws of thermodynamics, but he got pulled away on urgent grooming issues with the Fab Five. We set up an appointment to talk more next week.

Every Friday, Dave McCarty will join us to discuss a topic of interest to him and probably no one else but the author of this site.


Deuterium is what they use in the H-Bomb....Tritium is found in some watches and is used on some guns as part of the nightsights...


Nice. Excellent Job on all of this. I've been reading down through all of it, and I just thought it was time to say "Good Job!!";

Good Job!!

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