An attosecond is an SI unit of time equal to 10−18 of a second. (one quintillionth of a second). For context, an attosecond is to a second what a second is to about 31.71 billion years, or more than twice the age of the universe.
An attosecond is equal to 1000 zeptoseconds, or 1/1000 of a femtosecond. Because the next higher SI unit for time is the femtosecond (10−15 seconds), durations of 10−17 s and 10−16 s will typically be expressed as tens or hundreds of attoseconds:
- 1 attosecond – the time it takes for light to travel the length of three hydrogen atoms.
- 12 attoseconds – record for shortest time interval measured as of 12 May 2010.
- 24 attoseconds – the atomic unit of time.
- 67 attoseconds – the shortest pulses of laser light yet created.
- 100 attoseconds - fastest ever view of molecular motion
- 200 attoseconds (approximately) – half-life of beryllium-8, maximum time available for the triple-alpha process for the synthesis of carbon and heavier elements in stars.
- 320 attoseconds – estimated time it takes electrons to transfer between atoms.
See also 
- "attosecond". Memidex/WordNet Dictionary/Thesaurus. Retrieved 2011-04-14.
- Electron Motion Filmed, 28 Feb. 2008
- Exploring "Attosecond" Time. Visualising an Attosecond... How short is an attosecond?
- atto- [A toh] (Danish or Norwegian: eighteen; a decimal prefix used in the international metric system for measurements). Wordinfo.info (2007-04-05). Retrieved on 2011-01-23.
- "12 attoseconds is the world record for shortest controllable time".
- Watching Quantum Mechanics in Action: Researchers Create World Record Laser Pulse – 4 September 2012 – ScienceDaily. www.ScienceDaily.com. Retrieved on 2012-09-04.
- http://news.bbc.co.uk/1/hi/sci/tech/4766842.stm Science, 312, p424, April 2006 http://www.sciencemag.org/cgi/content/full/312/5772/424
- Electron timed hopping between atoms – physics-math – 20 July 2005. New Scientist. Retrieved on 2011-01-23.