Response to comment by Tin-Lun Ho on "Itinerant Ferromagnetism in a Strongly Interacting Fermi Gas of Ultracold Atoms", Science 325, 1521 (2009)

Understand

Ho claims in his comment that our experiment is direct evidence that itinerant ferromagnetism does not exist in ultracold Fermi gases.

• This claim is incorrect and based on an invalid estimate of relaxation times and an erroneous interpretation of the detectability of ferromagnetic domains.
• We point out that the experimental evidence is consistent with the existence of ferromagnetism, but further experiments are needed to distinguish a ferromagnetic ground state from a non-magnetic ground state with ferromagnetic correlations.