How do you translate "to realize" in We realized that we are not alone
?
I found the word realigi, but it means to make something real/true. It does not mean that we became aware of something.
The words you need are ekscii, ekkonscii, ekkompreni for fairly rapid realizations, and sciiĝi, konsciiĝi, komprenantiĝi for slower ones. Konstati can be used for realize but it is more along the lines of confirm, determine; i.e. it refers to a confirmation of a suspicion, an increase in certainty.
I'm sure there are many alternatives, but the first one to spring to mind is konstati.
From vortaro.net (PIV):
Benson (CEED) suggests konstati and konscii.
Wells suggests kompreni and konstati.
If you're at the point where you're asking questions like this, it would be a good idea to invest in a good bilingual dictionary - especially if this answer is not well-addressed in the on-line dictionaries.