Dark Energy

Tag archives for Dark Energy

What is Dark Energy?

You’ve all heard these words before. Dark Energy. But what is it, and why are we stuck with it? Let me start by telling you a story. Imagine, for a minute, that you have a candle. You know everything about this candle, including how bright it is and how far away it is from you.…

Say Goodbye to Virgo…

Aaah, the Virgo cluster. A huge cluster of hundreds of galaxies, and our closest large neighbor in the Universe. People have known for a long time that although Virgo is still redshifting away from us, it isn’t quite as fast as we would expect from the Hubble expansion rate of the Universe. Does this mean…

The Universe is Accelerating?

Sure, there’s dark energy, but what does that really mean? First off, there’s the bizarre phenomenon we see: very distant objects appear dimmer than we expect in a Universe filled with just matter and space. This supernova (above) should appear much brighter for how distant it is, based on what we know about supernova. This…

WMAP results: Cosmology from the CMB

The cosmic microwave background is the radiation left over from the big bang. It’s very uniform, 2.725 Kelvin everywhere. We’re moving with respect to it, so there’s a doppler shift, and we see that as a dipole moment in the Temperature. When we subtract that out, we see variations on the order of 30 microKelvins!…

startswithabang.com reader Andy has a great follow-up to his question on the Age & Size of the Universe, and asks: why does the CBR “appear” to come from a light sphere that “appears” NOW to be larger than the universe WAS when it first set off in a straight line on its 13.4 billion year…

Great things await you online…

Three awesome things are going on today for you, and I invite you to check them all out: The latest Carnival of Space is live, where you have your choice of 23 different astronomical topics to choose from. Of course, my post this week on galaxies and how they’re made is on there, too! Pamela…

First question!

Dave, one of my online chessplaying buddies, asked me this question (edited for appropriateness): Now this speeding up of the expansion of the universe: Do I understand correctly that one of the theories to explain why relates to “dark matter”? In real simple terms, what in the dark blue blazes is dark matter, and why…