The entire Universe outside our galaxy could have completely disappeared over 20,000 years ago and we still wouldn't know it yet. Our view of the Universe is actually what it looked like anywhere from thousands to Billions of years ago -with no way to see what it actually looks like "right now". Imagine if you looked out your front window and saw your yard as it was 6 months ago, neighbors house across the street a year ago, and houses a block or two away as they were several years ago. Also off in the distance you see the glaciers from the last ice age. That's what it's like looking out at the Universe.