无限二等分[0,1]这个区间之后还剩下啥?what's left after dividing an unit interval [0,1] infinitely many times?
Dividing an unit interval $[0,1]$ into two equal subintervals by the midpoint $\dfrac {0+1} {2}=\dfrac {1} {2}$, denote the left subinterval by $I_{1}=\left[ 0,\dfrac {1} {2^{1}}\right]$, next, divide $I_{1}$ into two equal parts by its midpoint, denote the left subinterval by $I_{2}=\left[ 0,\dfrac {1} {2^{2}}\right]$. Keep repeating this procedure indefinitely, what's left in the end ? Since referred infinitely many times here, it seems impossible to image the end case, but we could actually 'see' it!
Continue the process, obtaining a sequence of nested intervals$$I_{n}=\left[ 0,\dfrac {1} {2^{n}}\right], n = 1, 2, 3, ... $$Applying the nested intervals theorem there is only one point, one real number 0 contained in every $I_{n}$, i.e. $$\displaystyle\bigcap_{{n=1}}^{\infty}\left[ 0,\dfrac {1} {2^{n}}\right]=\left[ 0,0\right]=\{0\}$$
In conclusion, the only thing left after infinitely many times of these dividing is a point. More general, we don't need to divide each interval equally to form that sequence of nested intervals, since the nested intervals theorem doesn't requires that.