different permissions within a sharepoint list - on columns/items

I have a sharepoint list with a group of users who have permission to view. I would like to: have different permissions against specific columns within the list for example all users can read/write against column 1 only a subset of users can have read/write against column 2 however all users can view/read Is this possible and if so how please?

The reason is that we have baselined certain requirements in the list but still need to allow updates in other columns for the particular item. For example the 'description' column for each item cannot be changed without strict controls but the ability to change the 'update' column for the item should be available for all users.