(CNN) Friday marks the 77th anniversary of the attack on Pearl Harbor. While the day has always been a solemn reminder of the cost of war, it is increasingly becoming a reminder of the cost of time, as well.

The country is fortunate enough to have five remaining survivors who were aboard the USS Arizona on December 7, 1941. According to a report from Hawaii News Now , every year, some of these American veterans have been present at the Pearl Harbor memorial ceremonies in Hawaii. This year, however, none of them could make it.

The report explains that Lou Conter, Don Stratton, Ken Potts, Lonnie Cook and Lauren Bruner are all at an age where traveling is difficult. After all, it's been 77 years, and all of them are in their 90s.

The USS Arizona is launched at the New York Navy Yard in June 1915. The ship was destroyed during the attack on Pearl Harbor, and more than 1,000 crew members were lost.

An irreplacable legacy

As the number of World War II veterans, Pearl Harbor survivors, Holocaust survivors and indeed any person who carries such rich living history with them continues to dwindle, the threat of losing perspective on critical events begins to surface. That's why, experts say, it's important to not only preserve that history, but also to realize how deeply events like World War II continue to reverberate in the present.

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