Is there such a thing as negative infinity? (from my six year old son).

This may be helpful:

http://id.mind.net/~zona/mmts/miscellaneousMath/infinityAndSymbol/infinityAndSymbol.html

Rather than a negative infinity for our positive matter universe ...
such as the link suggests ... what about the laws which govern the
universe of negative matter ... smart kid for 6 to even grasp the
concept of something that's less than nothing.

yes, negative infinity = positive infinity = infinity

In terms that a six-year-old can understand, yes.

There are lots of ways to think about infinities, and whether
infinities actually "exist" is another question, but in math negative
infinity is a symbol that is often used. It's not a number, though, so
you can't do regular arithmetic with it.

negative infinity does exist. negative infininty is NOT equal to
positive infinity. But they both have the same cardinality.

sequence defined(n):  n is a natural number, ={1 2 3 4 5 6......
900879.... .........} forever

n diverges to  Infinity

-n={-1 -2 -3 -4 -5 -6........................-98984894986...............}

-n diverges to negative infinity.

Neg. Infinity is used in normal math 

Show sequence -1/n goes to zero:

By above -n goes to - infinity, so -1/n goes to -1/infinity=0.

Smart question from a six year old.