137 Just for fun How big is the Universe?
I am amazed at scientists that speculate on items like the chance of intelligent life in the universe. We are not able to conceive of how we would ever be able to travel to our closest solar neighbor, much less between galaxies. Just how big is the universe. The answer keeps changing as we come up with more powerful telescopes and as usual is just an estimate that is based on the “observable” universe. The fact is that we are not able to see all the way to the edge of the universe. Just ten years ago scientists estimated that there were at least 100 billion galaxies in the observable universe. Today that number has grown to a range of 500 billion to a trillion galaxies. These are numbers that are far beyond my grasp.
The Milky Way galaxy is not extremely large and yet is contains approximately 200 billion solar system. Our closest solar neighbor is Alpha Centauri. This isn’t a single star, it’s actually a triple-star system — three stars bound together by gravity. Alpha Centauri A and B are two bright, closely orbiting stars with a distant, dim companion named Proxima Centauri. The inner binary appears to the unaided eye as a single star, the third brightest in the night sky, but it lies 4.37 light years from the Sun. Faint Proxima Centauri is the one that claims the honor of being our true nearest stellar neighbor at only 4.24 light years away. If we were able to achieve a velocity of 10% of the speed of light (not a clue as to how we would achieve and maintain this) the round trip would take 85 years.
The estimated size of our galaxy is 100,000 light years in diameter. Do you think that is large, it’s not? The Andromeda galaxy, at a distance of about 2.5 million light years, also known as NGC 224 and M31 – is the nearest galaxy to the Milky Way apart from smaller companion galaxies such as the Magellanic Clouds. Andromeda is also a ‘spiral’ galaxy, like the Milky Way. From locations far away from the city lights, it can be spotted with the naked eye. The space between the two galaxies is 25 times the size of our galaxy! That would be quite a long trip.
Just how large is the universe? The proper distance —the distance as would be measured at a specific time, including the present—between Milky Way and the edge of the observable universe is 46 billion light-years (14 billion parsecs), making the diameter of the observable universe about 93 billion light-years (28 billion parsecs) assuming we are near the center.
I’ll leave you with the following to ponder: Since the best estimate is that the Universe started from a singularity 13.7 billion years ago how could it possibly be larger than 13.7 billion light-years in diameter?
This link will take you to a video I think you will enjoy: https://www.youtube.com/watch?v=Iy7NzjCmUf0