Can you look at a older time with Google Earth?

In google Earth select 'Historical Imagery' under View menu. This shows a timeline slider from which to select available satellite and aerial imagery allowing you to travel back in time to see how things looked in the past.

As of GE 6.0 there is time indicator in the status bar [lower-left of the map] showing the oldest imagery available.

For example, if you're in London then you can jump to 1945 to see WWII imagery.

3-D Building layer

Note that the 3-D building layer are current buildings and not associated with any particular time period so you may want to turn off this layer otherwise it may not match well with the older imagery.

Newer Imagery

Sometimes there are actually newer imagery available in Historical Imagery due to google's quality control process such as the newer image having more clouds or other defects making the older image "better".

Street View

Street View is not yet available in Historical Imagery to see older photographs.