In the double slit experiment I know that the electron fires as a particle one at a time then splits goes through both slits and recombined and interferes with itself and hit the wall creating a interference pattern. but I don’t understand how it can just change just by observing it. Like say you’re in the middle of a experiment and the interference pattern is building up and say if a ant sees the experiment how does that just make the electrons behave as a particle and rewrite the past and get rid of the interference pattern it had been building up.

In the double slit experiment I know that the electron fires as a particle one at a time then splits goes through both slits and recombined and interferes with itself and hit the wall creating a interference pattern.

But I don’t understand how it can just change just by observing it. Like say you’re in the middle of a experiment and the interference pattern is building up and say if an ant sees the experiment how does that just make the electrons behave as a particle and rewrite the past and get rid of the interference pattern it had been building up.