Several years ago I was debating the existance of God in an online forum. The debate was pointless, as my opponent was quick to draw arbitrary "micro-evolution, not macro-evolution" lines and resort to the inerrancy of the bible to 'prove' his point of view. He was a young-earther, too. Even though the debate stagnated after a while, there was one topic I had delivered, about which I was never able to extract a response. I posted one picture, and he put a full stop on all efforts he had been making in that direction. It was a nice moment for me. What was the topic, and what was my response?
As I stated, my opponent was a young-earther. I asked how, then, were we able to see light from stars millions of light years away? Did he not believe in the speed of light? No, he responded, the speed of light was fine. But the methods used to measure the distances to the stars were 'unreliable,' and that they were in fact much closer than we had been led to believe. This was when I struck.
Then how, I asked, do you explain the Hubble Deep Field image? I included a link to the hi-res image, and pointed out that, save for a few foreground stars, every glob of light in that image represented an entire galaxy of stars. And, if they were all within 6000 light years of us, how could the individual stars in these galaxies exist, considering they must be much smaller than a star needs to be in order to maintain nuclear fusion, and how would it have enough gravity to withstand being blown up by the nuclear energy?
This was what I couldn't get a response to. There is just something very compelling about a good visual.
The original Hubble Deep Field image (hires version here) was a snapstop of a tiny piece of the sky, like looking through a tiny keyhole. If you were to look up at the night sky, the little window this was taken from would be about the size of a dime -- held 75 feet away. And it showed more than 1,500 entire galaxies. What is really incredible is that the entire universe is like this, in all directions.
The image at the right is a more recent image, the Hubble Ultra Deep Field image (breathtaking hires version here). This image was taken from a section of the sky about 1/10 the diameter of the moon, over an exposure lasting 1,000,000 seconds. It reveals more than 10,000 galaxies. Aside from the foreground stars, these are all entire galaxies with billions of stars each.
It should again be noted that this is typical throughout the sky. That means that, lurking behind the moon, is at least 1,000,000 entire galaxies. And the full moon only takes up about half of 1/1000th of 1% of the full sky (360 degrees, north and south hemisphere), or 1/200,000th of the sky. Which results in roughly 200,000,000,000 galaxies that would be, barring any obstruction, visible from the Hubble telescope at a similar acuity as the HUFD.
Folks, that's one big universe.
The next step is to try to picture how big a galaxy is. A new image from Hubble shows exactly that. It is the highest detailed image of galaxy M81 (Bode's Galaxy, about 12 million light years away, shown left) ever taken. Fabulous hires version here. Yes, every single little pinpoint of light is a star. In the center they are so dense and the galaxy is so thick that they cannot be distinguished from one another. I don't even have to calculate how many stars that is, you can just see for yourself. (I've heard that 150 billion stars is average for a galaxy)
Another neat demonstration of how big the universe is -- by showing how small we are, is here in a series of image. First, the earth compared to the other rocky planets (and Pluto). Then to the rest of the planets. Then to the sun. Then the sun is compared to other normal stars. And finally, to the very largest stars. Earth grows invisible very quickly.
I don't want to write a complete rehash of my last post on nature -- but doesn't it feel just wonderful seeing how big the universe is? How could anyone possibly believe they are "God's chosen people" after seeing how amazingly tiny we are?