You can put a PS2 disc in a PS3, but whether or not it will play depends on the model of your PS3. The original 60GB and 20GB launch models are the only ones that are backward compatible with PS2 games. This is because these models have actual PS2 chips inside them, allowing them to run PS2 games just like a PS2 console would.
I personally own a 60GB launch model PS3, and I can confirm that it plays PS2 games flawlessly. I’ve been able to enjoy all my old PS2 favorites on it without any issues. It’s great to have that backward compatibility and not have to keep my old PS2 console around.
However, if you have a different model of PS3, such as the 80GB Metal Gear Solid bundle or any of the later slim models, you won’t be able to play PS2 games on it. These models used to have backward compatibility as well, but it was achieved through software emulation rather than having actual PS2 chips. Unfortunately, Sony eventually removed this feature in newer models, so they no longer support PS2 games.
I know this can be disappointing for those who were hoping to play their PS2 games on a newer PS3 model. It’s a shame that Sony decided to remove backward compatibility, as it was a great feature for those of us who had a collection of PS2 games. However, they likely made this decision to cut costs and make the PS3 more affordable.
So, in summary, if you have the original 60GB or 20GB launch model PS3, you can play PS2 games on it. But if you have any other model, you won’t be able to play PS2 games.