So I've been taking an astronomy course at Queen's Uni called, "Understanding Our Place in the Universe", and here's a rundown of the important stuff I learnt:
1. In space, we see things as they were, not as they are.
The universe is so vast and objects so far apart that by the time we see, for example, a star, that light is emits would have traveled over light years (sometimes hundreds, sometimes millions) before it reaches us.
It's like a metaphor for how we are. All that we see and recall is filtered or clouded by our memories, beliefs, and values, etc.
2. In black holes, time slows down.
My teacher pointed out that contrary to popular beliefs, blacks holes are not "unstoppable cosmic vacuum cleaners". Black holes are places where the gravitational pull is so strong that light cannot escape it. Mind officially blown.
It occurs when a star collapses and can exist in the center of a galaxy. So, the center of a galaxy is a black hole. This reminds me of a short story by Haruki Murakami where the protagonist uses donuts as a metaphor for life.
3. Galaxies canabalise each other.
I guess this is just the way of the world.
4. The universe is made up of 5% ordinary matter. That is what we can see like the stars and the planets (of which there are hundreds of billions of them). 25% is made up of dark matter; a weak gravitational force that cannot reflect light, hence, dark. The remaining 75% is made up of dark energy, which exerts a weak force that is pushing the universe. We know very little about dark matter and dark energy, and I find that exciting and scary at the same time.
5. The universe continues to expand.
The universe is always growing, but here's the thing: it is finite. If dark energy continues to grow (which it does), ordinary matter and dark matter will shrink. And at least in this TED-Ed video proposes, eventually will end. Watch the video, you will learn, a lot.
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