Re: A physics question about infinity

richard@xxxxxxxxxxxxxxx (Richard Tobin) wrote:
In article <r2q3g.599$xX5.41@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Norm Dresner <ndrez@xxxxxxx> wrote:
This is crap. Of course you can -- if properly defined -- add,
subtract, multiply, divide, and even exponentiate -- transfinite values.

But you have to be very careful doing this. Operations involving
infinity are not generally invertible. When manipulating ordinary
formulae you have to be careful to exclude the possibility of a
denominator being zero; once you introduce infinity you have to be
careful about almost every manipulation. For example, if y might be
infinite you can't deduce x=0 from x+y=y.

You're entitled to your opinion, of course. But I see virtually no
difference between the care which one must use when dealing with zero
and that which one must use when dealing with an infinity in an extended
number system. For example, corresponding to the example you gave:

For example, if y might be zero, you can't deduce x=1 from x*y=y.

David
.

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