Scientists think that they have discovered the maximum size limit for a black hole. Their educated guess, 50 billion suns. It is impossible to even imagine what something like that would look like. Of course it would be a lot smaller than if we put 50 billion of our suns together because we are talking about mass and the mass of a black hole is so crushed that gravity from it even sucks in light. One report about this phenomena stated that the size is 100,000 tredagrams, a measurement that is not very common, as a matter of fact I admit that I am wholly unfamiliar with it. I have heard of teragrams which have a mass equal to 1,000,000,000,000 grams. The truth is that there is really no limit on the size of black holes, but there is a limit on how big they could have become since the universe was formed, or so say the scientists. So far the largest black hole ever observed is about one third of that size, but here is the sticker as I like to say, we can't observe black holes directly. We can only guess at their size by the disk of matter that is being sucked into them.

Since I am mentioning accretion disks, those are the disks of matter swirling around a black hole and other objects, I have to state that scientists were able to see one of these disks that was around a neutron star, which is another extremely dense object with a powerful gravity source. This was thanks to the fact that there was a massive explosion on the surface of that star. The explosion poured out more energy in three hours than our sun gives off in 100 years. The explosion was so strong that the disk around the star actually buckled, but it recovered in about 16.6 minutes. Neutron stars are so compact that they are usually very small even though they are incredibly massive. This one was only about 10 miles across. The star itself was about 25,000 light years away. One of the scientists stated, "This is the first time we have been able to watch the inner regions of an accretion disk, in this case literally a few miles from the neutron star's surface, change its structure in real-time. Accretion disks are known to flow around many objects in the Universe, from newly forming stars to the giant black holes in distant quasars. Details of how such a disk flows could only be inferred up to now." Since we can't observe black holes directly, Neutron stars contain the most mass of any object that can be observed directly so far.

The biggest black hole ever discovered as I stated before, was about 1/3 rd the size of the 50 billion sun's size. To be exact it is about 18 billions suns in mass. It is so big that it is roughly the size of a galaxy. A much tinier black hole is nearby and astronomers are using it to test Einstein's theory of general relativity as it orbits the bigger black hole. It is perfect for this test since the gravity is more intense that anything else ever observed. We got lucky with this giant black hole because it is 3.5 billion light years away. You certainly wouldn't want to be too close to this monster. It is at least 6 times bigger than any other black hole discovered to date. The smaller black hole is tiny, only about 100,000,000 suns in size, poor tiny critter. It takes about 12 years for the small black hole to orbit the huge one. What is interesting about all this is the smaller black hole punches through the disk of matter surrounding the huge black hole 2 times on each orbit causing a bright outburst of light. Scientists claim that the movement and the results from these two black holes interacting prove that Einstein was correct.

The spiral galaxy Andromeda is a lot like our Milky Way. It is only 2.5 million light years away, which is pretty close cosmically. Both galaxies are coming toward each other at a speed of about 62-87 miles per second and the two galaxies will probably collide some time in the future, but that is not written in stone as they say. Andromeda is larger than our galaxy. When scientists look at what is known as the local group, they are the galaxies near by, ours is thought to be the most massive even though it is not the biggest. The reason for this is that most scientists think that it contains the most dark matter. The problem with that is that the Spitzer Space Telescope showed that Andromeda has over a trillion stars and the Milky Way only about 4 billion. In the center of Andromeda is a cool area that scientists now believe contains a black hole with the mass of 30 million suns. If Andromeda and the Milky Way do collide, most of the stars will just pass between each other, since there is so much room between stars. What if the black hole in Andromeda collides with the black hole in the center of our galaxy? That might make for interesting fire works.

Last year a group of international scientists used the data and physics of black holes to create a very sophisticated model of the universe. They took this program and installed it on a supercomputer and got what some have said is the most accurate model of how the universe evolved. The scientists believe that the structure of black holes are vital, when figuring out the structure of the universe and they also feel that future telescopes may be guided by them. It is felt that this way observers will be able to locate the earliest cosmic events and thus figure out the development of our universe. It has been found that black holes regulate the formation of at least some galaxies. One scientist stated that black holes have a self regulating system and never swallow whole galaxies. The simulation that was developed covered a time scale of 100 million light years.

Black holes are fascinating indeed. Whether we fully understand them yet is another story. As I have often said we have never observed one directly, we only see the disk of material around one that is being sucked in. There are so many questions connected with black holes, such as the question of white holes. That is what some scientists suspect is at the other end of the tunnel that is created when matter is sucked into the black hole. They feel that this is where the matter comes out from and this creates a bright light. This is still unproved. There are a few scientists that feel that the other end of a black hole is a different dimension and matter from this universe is being dumped into it. Then there are those that think that a black hole creates a rip in time and space and it could be that matter is being sent into the past or future. Whatever a black hole is or isn't, it is still one the grandest and most powerful object in our universe.