Six Degrees of Kevin Bacon

The trivia game Six Degrees of Kevin Bacon, inspired by the film Six Degrees of Separation, requires a group of players to connect any film actor to Kevin Bacon as quickly as possible and in as few links as possible (see Small World Phenomenon). The name, of course, is a pun on the film title and its rhyming with Bacon's name. The concept is simple, but finding the smallest number of links can be difficult. The way you link an actor with Bacon is like so:

• Pick a film actor, any film actor.
• Link the actor you've chosen to Bacon via the movies they've shared with other actors until you end up with Kevin Bacon himself.

Here is an example, using Elvis Presley:

1. Elvis Presley was in Change of Habit (1969) with Edward Asner
2. Edward Asner was in JFK (1991) with Kevin Bacon

Therefore Elvis Presley has a Bacon number of 2.

The game has expanded to become more about linking two film actors than just one actor to Kevin Bacon. The name is still retained, however, because it has been shown that Bacon is a common link member in a chain.

The traditional Six Degrees of Kevin Bacon game

Very few actors have an infinite (or undefined) Bacon number, meaning that they cannot be linked to Bacon in any number of connections at all. For instance, Fred Ott appears in the 1894 Edison Kinetoscopic Record of a Sneeze; he was the only actor in that film and also acted solo in Fred Ott Holding a Bird -- the only films in which he appeared. Most actors, however, can be linked to Bacon.

Variations of the Six Degrees of Kevin Bacon game

The Six Degrees of Kevin Bacon game sometimes fails to model the real world as it allows both forward and backward linkings. Very frequently, only one kind of linking is allowed between two nodes.

Forward linking

For example, the spreading of HIV, the virus that causes AIDS, is forward in time. If John Doe gets HIV on January 1, 2004. Jane Doe, who only had sex with him two days before that could not get the virus from John.

For John Doe to transmit the virus to Jane Doe, it may require following steps:

John Doe -> Jack (5 weeks later) -> Tom (18 months later) -> Jane Doe (2 years later)

Backward linking

However, if John Doe is running a peer-to-peer file exchange program like BitTorrent, he needs links backward in time. He does not care who will get a piece of the file in the future. He wants to know who already had that piece of file at hand.

For John Doe to receive a piece of file, that particular information could be travelling in this manner:

John Doe <- Jack (2 minutes ago) <- Tom (5 hours ago) <- Mary (4 day ago) <- Seed (1 week ago)

So there are two ways to link, for example, Jennifer Lopez with Kevin Bacon:

• Forward linking from Lopez to Bacon

1. Jennifer Lopez was in U Turn (1997) with Sean Penn
2. Sean Penn was in Mystic River (2003) with Kevin Bacon

• 1997 -> 2003

• Backward linking from Lopez to Bacon

1. Jennifer Lopez was in Gigli (2003) with David Pressman
2. David Pressman was in Pyrates (1991) with Kevin Bacon

• 2003 <- 1991

Bi-directional linking

Anyone with a Bacon number of 2 could not have a link of both forward and backward steps. However, with many people who died long ago, pure backward linking is simply impossible, if the use of stock footage is ruled out. For example, John F. Kennedy, who died in 1963 could not be performing with anyone after 1975, Bacon's first TV appearance, or 1978, his first film appearance.

• Shortest Path from JFK to Bacon (A)

1. John F. Kennedy was in Zapruder Film of Kennedy Assassination (1963) with Jean Hill
2. Jean Hill was in (1992) with Gary Oldman
3. Gary Oldman was in Murder in the First (1995) with Kevin Bacon

• 1963 -> 1992 -> 1995 (forward steps)

• Shortest Path from JFK to Bacon (B)

1. John F. Kennedy was in Zapruder Film of Kennedy Assassination (1963) with Jean (II) Hill
2. Jean Hill was in Beyond 'JFK': The Question of Conspiracy (1992) with Edward Asner
3. Edward Asner was in JFK (1991) with Kevin Bacon

• 1963 -> 1992 <- 1991 (bi-directional steps, backward steps impossible)

Distant links

Elsa Masriera has a Bacon number of 7. If bi-directional links are allowed.

• Shortest Path from Elsa Masriera to Kevin Bacon (A)

1. Elsa Masriera was in Madre sin saberlo (1927) with Mercedes Olivares
2. Mercedes Olivares was in Bajo dos banderas (1926) with Edmundo Fuenzalida
3. Edmundo Fuenzalida was in Los Cascabeles de Arlequin (1926) with Placido Martin
4. Placido Martin was in Suena mi amor (1946) with Chela Bon
5. Chela Bon was in Curse of the Stone Hand (1964) with John Carradine
6. John Carradine was in The Sentinel (1977) with Eli Wallach
7. Eli Wallach was in Mystic River (2003) with Kevin Bacon

• 1927 <- 1926 -> 1926 -> 1946 -> 1964 -> 1977 -> 2003 (bi-directional)

• Shortest Path from Elsa Masriera to Kevin Bacon (B)

1. Elsa Masriera was in Madre sin saberlo (1927) with Mercedes Olivares
2. Mercedes Olivares was in Bajo dos banderas (1926) with Edmundo Fuenzalida
3. Edmundo Fuenzalida was in Los Cascabeles de Arlequin (1926) with Placido Martin
4. Placido Martin was in El Ultimo galope (1951) with Yoya Martinez
5. Yoya Martinez was in "Marron Glace, el regreso " (1996) with Walter Kliche
6. Walter Kliche was in The Lawless Land (1988) with Xander Berkeley
7. Xander Berkeley was in Apollo 13 (1995) with Kevin Bacon

• 1927 <- 1926 -> 1926 -> 1951 -> 1996 <- 1988 -> 1995 (bi-directional)

William Rufus Shafter, with a Bacon number of 8, is among the current record holders. There could be some others with a higher number.

See also

• Bacon numbers for a lot more information on Bacon numbers and how to calculate them.

External links

• The Oracle of Bacon, with an automated Bacon calculator provided by the University of Virginia
• The Amazing Baconizer, finds the shortest path between any two books, movies, or CDs offered on Amazon.com, by building paths out of the "people who bought this item also bought these ten other items" links.