1. Their observable universe also used to be the size of a grapefruit. �����ǵĿɼ�����Ҳ����ֻ�������ְ�Ĵ�С��
2. The diagram below shows the hidden and observable states in the weather example. ��ͼչʾ���������������е���״̬�Լ��ɹ۲�״̬��
3. Spacetime also appears to have a simply connected topology, at least on the length-scale of the observable universe. ʱ���ƺ�Ҳ��һ�������ӵ����˽ṹ�����ٵij��ȣ���ģ֮��ɼ������档