# Bosonic fermions?

**URL:** <https://boards.straightdope.com/t/bosonic-fermions/69809>\
**Category:** Factual Questions\
**Created:** [June 22, 2001, 5:31pm UTC](https://boards.straightdope.com/t/bosonic-fermions/69809 "2001-06-22T17:31:38Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\
**Post date:** [June 22, 2001, 5:31pm UTC](https://boards.straightdope.com/t/bosonic-fermions/69809/1 "2001-06-22T17:31:38Z")

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I’m sure this has been discussed here before, but my search was fruitless. My question has to do with Bose Einstein condensates, and more particularly with how the atoms of the condensate (eg. rubidium) are bosons. Atoms are made of fermions, no? How does an atom (a collection of fermions), or an ensemble of atoms (a collection of a collection of fermions), become a boson? Is there a net cancellation of the fractional spins of the constituents that leaves an integer spin?

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**Author:** ![Triskadecamus](https://avatars.discourse-cdn.com/v4/letter/t/b19c9b/32.png) [@Triskadecamus](https://boards.straightdope.com/u/Triskadecamus)\
**Post date:** [June 22, 2001, 6:30pm UTC](https://boards.straightdope.com/t/bosonic-fermions/69809/2 "2001-06-22T18:30:20Z")

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The original Bose-Einstein experience used bosons. In 1999 Debora Jin, and Brian Demarco achieved the supercooled state using [fermions,](http://www.onr.navy.mil/onr/newsrel/nr990909.htm) since then others have achieved the same.

## Tris

“Physics sould be simple enough to explain to a barmaid.” Albert Einstein

“Man, you should see the place Einstein used to go drink!” Triskadecamus

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**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\
**Post date:** [June 22, 2001, 9:55pm UTC](https://boards.straightdope.com/t/bosonic-fermions/69809/3 "2001-06-22T21:55:57Z")

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Even though the constituent particles of an atom are fermions the atom itself can be a boson. Intrinsic spins add so if the atom has an even number of particles it’s a boson.

Fermionic atoms cannot form a Bose-Einstein Condensate.

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [June 22, 2001, 10:35pm UTC](https://boards.straightdope.com/t/bosonic-fermions/69809/4 "2001-06-22T22:35:36Z")

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> [@](#):
>
> Fermionic atoms cannot form a Bose-Einstein Condensate.

Not directly, but they can pair up in such a way that the bosonic pairs form a superfluid, rather than the atoms themselves. The best-known example is He-3, but they’ve probably managed to pull it off with a few other fermions.

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**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\
**Post date:** [June 22, 2001, 11:56pm UTC](https://boards.straightdope.com/t/bosonic-fermions/69809/5 "2001-06-22T23:56:19Z")

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> [@](#):
>
> \*Originally posted by Ring \*  
> \*\*Intrinsic spins add so if the atom has an even number of particles it’s a boson.  
> \*\*

Aha…  
Thanks.