Is scientific knowledge absolute

No, a lot of our knowledge isn’t absolute.
There is a lot that is absolute, like "The Earth is round", but some knowledge is not guaranteed. 
For example, people used to think "A fungus plus a algae make a lichen" but it’s actually a fungus, an algae and another type of fungus. 
This just shows that we’re always learning new things about our world, and someday we might be proven wrong on something big!