# Long Time Intervals

Harrison Brown discusses the significance of long time intervals and describes how radioactive dating arrives at an estimate for the age of the earth. For more info on PSSC, its history, and films, visit http://www.afana.org/psscfilms.htm

- Kind: Educational
- Year: 1959
- Runtime: 24 min
- By: Educational Services Inc
- Genres: Education, Science
- Archive: [Internet Archive](https://archive.org/details/LongTimeIntervals)
- Licence or status: none stated by the archive
- Who can watch: Kids profiles and older (the archive gives no rating; placed by Invisible Network from its collection and subjects)

[Watch now](https://invisiblenetwork.ai/watch/archive/ia/LongTimeIntervals?play=1)