First Science From A Virtual Observatory

mindpixel writes "I first mentioned Virtual Observatories in my July 2000 Slashdot interview. Now, nearly four years later, Spacetelescope.org is reporting a European team has used the Astrophysical Virtual Observatory (AVO) to find 30 supermassive black holes that had previously escaped detection behind masking dust clouds. The identification of this large population of long-sought 'hidden' black holes is the first scientific discovery to emerge from a Virtual Observatory. The result suggests that astronomers may have underestimated the number of powerful supermassive black holes by as much as a factor of five."

Comments

Re:My first question

[mforbes]

Good question, but no. You idea presupposes that there is a center to the universe, from which the galaxies (and the black holes contained therein) have expanded, much like shrapnel from an explosive. Think of it instead as being like points on a balloon as it expands; they're all getting further away from eachother, but none of them can lay claim to being at the center. Therefore there is no point at which one of them is 'outside' the others. Without that vantage point, there is no way to pull.

Re:My first question

[GregChant]

Grandparent is mistaken. Dark energy is just normal energy: it gets its name from a problem that astrophysicists have had since Einstein; if the Universe is expanding, and there is only so much matter and energy that we've accounted for (which, by itself, would cause a "big crunch"), what is causing the expansion?

Astrophysicists call the energy required for such an expansion "dark energy" not because its "evil", but because they can't see it (in the figurative sense).

Re:My first question

[abbamouse]

You are referring to dark matter: the "missing mass" problem. There isn't enough mass to account for the fact the universe is expanding (and apparently is nearly flat). Hence, there must be some form of matter we cannot see, i.e. dark matter.

Dark energy is a second conundrum which does not depend on the mere fact the universe is expanding. It is a puzzle generated by the fact that the rate of expansion seems to be increasing! It's as if something is actively pushing space apart; since gravity grows weaker with distance the push becomes more and more important as the universe expands. Hence the "cosmological constant" -- it would provide a constant push that would initially be overwhelmed by gravity (so the expansion of the universe would begin to slow) but would remain constant everywhere regardless of distance and would thus overcome gravity over very large distances. The result? A universe that goes "bang," inflates rapidly, and then begins to slow down as space expands. Forward billions of years...and the slow expansion starts to speed up again, faster and faster until everything flies a p a r t . . .