Age of the universe - they make a new guess

"A few years ago, the WMAP spacecraft looked at the Universe much as Planck has, and for the time got the best determination of the cosmic age: 13.73 +/- 0.12 billion years old. Planck has found that the Universe is nearly 100 million years older than that: 13.82 billion years."

They keep changing their estimates. If they knew the answer, then the answer would not change. But they are just guessing. If they KNEW answer, then they would not have to change the answer. I am not obligated to accept a man's guesses. "Science" means knowledge. Guessing is not knowing.