I want to do something like "SELECT field1 / max(field1) "

Like the title says, I would like to make it so all the values returned are 0-1. So my first try was like in the title, but I get an error about not being able to mix aggregate and raw field types. Is something like this possible? Thanks see below for better explanation.

Select field1 from measurement1;
Time field1
1 10
2 15
3 20

But I want
Time field1
1 .5
2 .75
3 1