Infinity is something without bounds that goes on forever. But in
mathematics, infinity can be defined as any real number larger 9.9 ×1099.
So how do we grasp the concept of infinity? Stand between 2 mirrors
and you would see your image go on an infinity number of times (it never
ends).
The concept of infinity was first conceived by the Greeks to explain
limitlessness. Also the Hindus used it for their creation story when they
said there are limitless number of creators thus they don't know the
first one.
There is something funny about infinity: some
infinity are greater than others! How many real numbers are between 0 and
1? The answer is infinity. How? We have 0.1, 0.01,0.001,
0.0001,.....0.2, 0.21, 0.22,... If you count all the real numbers
between, they are greater than 9.9 ×1099. Now how many real numbers
are between 0 and 2 ? It's also infinity but surely it is greater than
the first infinity.
This has been exploited in cosmology. If we are to measure the
radius of the universe in femto meters (1015), we might be
approaching a value close to infinity but if measured in light years
(9.64 ×1015 ) we would get a value far from infinity. So to avoid
saying infinity femto meters (which is not an actual value) we say
100,000,000 light years which is finite.
