With vim, a file seems to be filled with '^@' characters even though it was created as an empty file.

Issue

I created an empty file with dd command but it is filled with '^@' characters. Why?

[root@host]# dd if=/dev/zero of=emptyfile.dat bs=1M count=10

[root@host]# vi emptyfile.dat
^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@
^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@
.... snip ...