Is this world real? is this world the same as it was before Noah? has it changed after Noach? can the reality of the world change in time or it is the same?

Of course this world is real for us. Some commentaries write that the climate and atmosphere changed for the worse after the Flood, thus explaining why man used to live more than 900 years. Nevertheless, afterwards, the Torah tells us that the seasons that we have today won't change any more (Breishit 8, 22). That doesn't mean that the ozone layer and other things won't change, especially as a result of man's actions or inaction.