Quasars, Black Holes, and the Big Bang

So now, let's move out billions of light years and see if we find any new inhabitants of the universe. In fact, we do! At a distance of between 8 and 12 billions light years, we find a large population of objects called quasars. These objects were first discovered in 1963 as stars that appeared to be emitting radio waves ("quasi-stellar radio sources," or "quasars" for short). The current thought is that quasars are the active nuclei of very distant (and fairly young) galaxies. It is theorized that there are giant black holes at the centers of these galaxies. As matter falls into these black holes, it emits tremendous amounts of energy which makes quasars visible over half way across the universe. In the constellation Virgo is 3C 273. Through a telescope, 3C 273 appears simply as an ordinary star. It is a better view if we look at it in the radio part of the spectrum.

This structure of two lobes is further evidence of the presence of a central black hole. As matter falls into the black hole and forms a dense accretion disk around the equator of the black hole, these lobes of radiation squirt out of the poles of the black hole. 3C 273 is just barely visible through a small telescope such as those at the ETSU observatory. It is 3 billion light years away, so when you see the light from this object, you are seeing light that left its source when the most complicated life on Earth was single-celled. Another example of a quasar is 3C 48 located in Triangulum.
The light from this source is about 7 billion years old and therefore is older than the Sun and Earth which are only about 4.5 billion years old.

So what happens if we look farther and farther away? At a distance of about 15 billion light years we see a wall of light that was emitted shortly after the big bang. And what other evidence is there of the big bang? In fact, all of the objects we have mentioned that lie beyond our local group of galaxies are rushing away from us at a rate proportional to their distance. It is fairly easy to determine these recessional velocities and therefore it's easy to estimate distances (although there is a good bit of uncertainty in these estimates).

We might interprete the big bang as something like this.

This picture does reflect the idea of expansion, but it is misleading and lmplies the big bang was some sort of explosion. This is not at all the case. Unfortunately, for an accurate view we need to spend some time exploring 4-dimensional geometry. Perhaps in a future show...

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