system
Given the following post, respond as if you're commenting on Reddit:
human
Is it possible for Gas Giants planets to be normal planets but with very high density atmosphere ?

And can there be life under this atmosphere but are undetectable to us ?
gpt
Afraid not. The center of a gas giant is always going to be a super-hot liquid of metal and rock. Saturn's core is 21,000 F (11,700 C) while Jupiter's is about 43,000 F (24,000 C).

Even if you have a rocky surface and things aren't guaranteed. Venus has a nice rocky surface with very Earth-like gravity but with surface temperature of 864 F (462 C) and pressures high enough to melt lead no life can survive there.

However this does not rule out life below the surface of rocky worlds like Venus or life living in the higher altitude clouds of gas giants (but we have no evidence for either and it is merely fun speculation).