Wednesday 16 January 2013

LARGEST OBJECT IN THE UNIVERSE

Artist impression of a Quasar (Image Credit : NASA)
The universe is huge. That is an understatement. How huge? Well, to truly explain it to you, I would have to use a range of expletives, which I don't think I would like to do as I do not want a flood of complaints on here. But suffice it to say that it is huge beyond imagination, even beyond the imaginations of all the scientists that have ever lived put together.

And there are huge things in our universe as well such as stars, galaxies, nebulae, clusters, walls, voids and all that. For example our own Milky Way galaxy is about 100,000 light years across. So travelling in a starship that can move at the speed of light (which is 300,000,000 meters per second!), you'd need to travel non-stop for 100,000 years to cross from one side to the other. That is huge.

But then we have bigger galaxies and even bigger clusters of galaxies such as our own Virgo Supercluster. This supercluster is where our galaxy resides in. This supercluster is 110 million light years across. That is huge.

Then we have Voids. Voids are just empty space between matter in the universe, matter such as galaxies, nebulae, clusters and superclusters. Voids can get really big, such as the Eridanus Supervoid which is 500 million light years across. That is huge.

Anything bigger then? Duh..yeah! Recently we humans have found something even bigger, stupendously bigger. This thing is called a Large Quasar Group. First before I go jumping in to how huge this thing is, what is a Quasar?

A Quasar is a very energetic and distant active galactic nucleus. A quasar is a compact region in the center of a massive galaxy surrounding its central supermassive black hole. Its size is 10–10,000 times the Schwarzschild radius of the black hole. The quasar is powered by an accretion disc around the black hole.

The Schwarzschild radius is the distance from the center of an object such that, if all the mass of the object were compressed within that sphere, the escape speed from the surface would equal the speed of light. An example of an object smaller than its Schwarzschild radius is a black hole. So, a Quasar is 10 to 10,000 times bigger than the black hole in which it exists.

See what happens is that a black hole sucks in matter around it. As that matter falls into the black hole, it spins while falling, kind of like water draining in a sink. But the black hole spins the matter so fast that sometimes it spits out some of this matter in the form of a jet of energy. This jet of energy is a Quasar.

So we can surmise that a Quasar basically sits in the middle of a galaxy. Quasar = galaxy. So, a big group of Quasars = a big group of galaxies i.e. clusters or as they get bigger, superclusters. The new winner of the biggest object in the universe contest is what scientists call a "Large Quasar Group" or LQG. So basically an LQG is nothing but a large group of galaxies or what I like to call LGG.

This newly discovered LQG is 4 billion light years across. Yup you read that right, 4 billion! The observable universe is 93 billion light years across, this thing takes up 4 of those. How big is that? !@#$%^&*()?<>{} big, ok? Get the big picture?

The Royal Astronomical Society explains:
To give some sense of scale, our galaxy, the Milky Way, is separated from its nearest neighbour, the Andromeda Galaxy, by about 0.75 Megaparsecs (Mpc) or 2.5 million light-years. Whole clusters of galaxies can be 2-3 Mpc across but LQGs can be 200 Mpc or more across. Based on the Cosmological Principle and the modern theory of cosmology, calculations suggest that astrophysicists should not be able to find a structure larger than 370 Mpc.
The LQG is about 1,200 Mpc across - or four times larger than it should be. Phew, the universe is truly mind bending, isn't it? So still think it made itself? Who's your daddy now?

To find out more about how big the universe is, try reading my new book - "How Big Is Our Universe - Answers To The Question You've Always Asked". You can click on the image below to hyperjump there.


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