Question

why can't we get direct information about the interior of the earth​

Answer 1

The interior of the earth is so hot that everything melts as it approaches the inside.

Answer 2

It is impossible to reach the center of the earth with the technology which we have. The temperature at the center is estimated to be about 5000 degrees celcius. So, we can only get info from earthquake waves.

Hope it helps!

-Violet