[erlang-questions] Why are messages between processes copied?

[H. Diedrich]

Hi list,

I had naively thought that Erlang would be sending process messages 
around profiting from the fact that data is immutable and NOT copying 
it. And really just send a 'pointer'.

Why is that not so, it should be a huge gain from immutable data, 
especially with bigger data. You don't have to copy, knowing that your 
data is immutable.

Thanks for a link or a brief,
Henning