There are many things about the universe that disprove YEC:
(1. The speed of light. If the universe is 6000 years old, then why can we see stars millions of light years away?
(2. Black holes. If the universe is only 6000 years old, stars would not collapse and black holes wouldn't exist.
(3. Star and planet formation. Stars and planets can't form in 6000 years.
There are many more examples, I will post them all when I have more time.
(1. The speed of light. If the universe is 6000 years old, then why can we see stars millions of light years away?
(2. Black holes. If the universe is only 6000 years old, stars would not collapse and black holes wouldn't exist.
(3. Star and planet formation. Stars and planets can't form in 6000 years.
There are many more examples, I will post them all when I have more time.