First, let me say that’s a bit late, and my brain is somewhat foggy as a result, so I hope this doesn’t sound too idiotic…

OK. The “Ultimate Fate of the Universe”, as I understand it, pretty much depends upon two things: the rate of expansion and the average density of the universe. With respect to the density, if it is greater than some critical value, gravitational forces will ultimately stop the expansion and contraction will ensue. Similarly, if it is below this critical value, the universe will expand indefinitely.

Now, when we add up all the observable mass in the universe, we get numbers that are only about 10% what is required for even the lowest current estimated expansion rates; some matter is apparently missing if observations are to match calculations (the calculated mass of the observable stuff doesn’t account for all the observable gravitational effects). Thus, “Dark Matter” is postulated to account for this missing matter. However, even with the addition of this Dark Matter, we are still below what is required for the lowest expansion rates (stop me if I’m completely off here!). Scientists appear to be at a loss to explain this.

So…here’s what I’m thinking: what if energy is factored in? My interpretation of Einstein’s famous equation, **E=mc[sup]2[/sup]**, is that energy and mass are basically interconvertable. Or, put another way, the ratio of energy to matter, if we look at the entire universe, is a constant. So, if we could determine the amount of energy out there, couldn’t we determine its effective mass, if it were condensed to matter? And might not this mass account for the missing mass? Granted this is probably *way* out there, but, hey, I was just wondering

In a related vein, if energy and mass are interconvertable, is it conceivable that energy can be affected by gravity? Or, perhaps more appropriately, can a sufficiently large concentration of energy have the same effects on space-time as an equivalent mass?

I apologize if these sound idiotic to those of you who actually know something about this stuff (I’m only now getting around to reading Hawking), and hope you take into account my addled brain before you tear me to shreds *too* harshly