First off, I was kidding...it was a reference to a Doctor Who episode that had a "Cold Star" that gave off cold...

And second off...

I was again kidding....I'm fully aware of the physics involved...

Third, temperature is technically not defined based off of kinetic energy...that actually would be a terrible definition since kinetic energy is 100% relative....temperature actually is the inverse of a more important physical quantity, the (thermodynamic) beta value...the beta value represents the relationship between changes in energy and changes in entropy (it's proportional to the partial derivative dS/dE -- I don't remember which things are held constant but probably volume and/or number of particles since I know those affect entropy)...

Finally, temperature, given the more rigid definition above, actually can be negative if you have a system where increasing energy actually decreases entropy...there are few pathologies in quantum physics where adding energy decreases entropy...certainly not relevant to most systems but it is doable and definitely does not require negative mass....

That is a very interesting article.

However, it looks like it is way too early to put much credence in the results of this experiment. I was unable to track down any peer reviews, any attempts by other physicists to recreate the experiment, or any attempts to show where there may have been errors in how the experiment was performed (perhaps because there hasn't been sufficient time for any of this to take place). And new discoveries, such as this appears to be, take time before it gets sufficient scientific review to become accepted. It may show that artificial gravity is possible, or it may just be a fluke. Let's give it time to mature and see how well it stands up to scientific scrutiny.

There are many things in the article that certainly stands our understanding of physics on its head. And some of the conclusions sound far fetched. But it is early yet. Maybe their experiment really did show that absolute zero isn't the lowest achievable temperature. Maybe the conclusions they reached are not supported by what they observed. It takes years for scientists to work these things out. Give it time. Lets not use this in GalCiv just yet.

Temperature is a measure of the average kinetic energy of the particles within a given volume. It may not strictly speaking be defined by kinetic energy, but it is a measurement of it, and absolute zero is defined as the point at which the average kinetic energy of the particles in that volume is zero, which leads to the conclusion that the velocity of said particles is also zero.

I honestly don't care that much about how 'accurate' certain star colors are. if you want realism go play some simulator game. 

Still, there is the argument that stars unlike our own exist in a different galactic super-cluster beyond the (current) visible range of telescopes. Or that Galciv3 takes place in a different universe where the laws of physics are close, but different enough from ours to allow such things to exist.
(Technically multiverse theory would guarantee that a universe with green stars exists somewhere )

OR, you could go with the argument that this is a completely fictional piece of work, for entertainment purposes only; and scientific accuracy is not guaranteed, implied, or required.
I'd rather they make the game play good, then sit around and argue about what stuff is scientifically accurate anyway....

Don't take this topic too serious. You never know what crazy ideas might come up and end up in the game, making it better.

Dear lord, all this hard science... I prefer hard por...ridge.

Maybe from your perspective...this is the third thread that has discussed the realism of "green stars" (one on GC3, one on GC2, one on Sins)....each and every time, someone tries to claim they "understand physics" and use "science" to explain why green stars are realistic...each and every time, I have tried to explain why that is incorrect....naturally of course, these threads wander....people who don't understand science continue to argue and I (like others) get to a point where it is far easier to just throw in obviously bogus responses because it is a lost cause...

It's one thing to "correct" me when I'm making a joke (thought it was obvious that "cold stars" was not an attempt at realism)...it's another thing to "correct" a joke with another wrong explanation....of course, it's a matter of perspective -- what's "funny" depends on how much you actually know about the physics being discussed...