Question #5d006
1 Answer
Jan 29, 2018
The speed of light.
Explanation:
The constraint in our observations is the speed of light. Since we put the age of the universe at 13.7 billion years it follows that we can only detect light that is 13.7 billion years old. Astronomers, however, hypothesized that the universe expanded in the first millionths of existence to 1/2 of its present size. That reason alone pushes space out to 20 million light years. And now astrophysicists speculate that the size of the universe is about 90 billion light years across. If there is something sitting out there at 40 billion light years we can never detect it.
