With the last year or so I came across a great discussion in these forums about the different types of infinity. It had never occurred to me there would necessarily be different types with different "values". How about zero? Are there different mathematical concepts regarding it or are all zeros "equal" ? Any different types of zero with different mathematical meanings?? Any difference between approaching from plus, or minus, or "i" ?? Is a 1 x 1 matrix with zero the same as, say, an n x n matrix with all zeros? [Physically, "zero" for physicsts is not always so clear...like absolute zero; zero energy in a volume of spacetime isn't...it's zero point energy with virtual particles,quantum activity; zero time in cosmology (less than 1 Planck time) etc,etc. ] Thank you. PS: for those interested, Wikipedia has a lot of interesting insights on "zero" here: http://en.wikipedia.org/wiki/Zero Among them: Zero is an even number; Zero is the smallest non negative integer;there is no calendar year zero but there is a cosmological year zero.