Could Earth be someone else’s science experiment?

It’s possible as a philosophical or science-fiction idea, but there’s no evidence that Earth is literally someone else’s science experiment.

A few related ideas are often discussed:

• Simulation hypothesis: the idea that our reality could be a computer simulation created by an advanced intelligence.
• Zoo hypothesis: the idea that advanced aliens may be observing Earth without contacting us.
• Directed panspermia: the idea that life on Earth may have been intentionally seeded by an advanced civilization.

These are interesting thought experiments, but none of them is established science, and none has been confirmed.

So the short answer is: maybe in a speculative sense, but we have no good evidence that Earth is an experiment.