TUNABLE CHEMISTRY IN BOSE-EINSTEIN CONDENSATES (BECs) has been demonstrated by an MIT group (Wolfgang Ketterle, 617-253-6815), allowing researchers to choose whether atoms in this new state of matter attract each other, repel each other, or hardly interact at all. A BEC is a gas of atoms so cold and so dense that they overlap and act as a single, unified entity (Update 233). To control the chemistry of a sodium BEC, the researchers turned on a magnetic field which slightly altered the shape of the electron clouds surrounding each atom. This in turn could modify the force that the atoms applied on each other (Nature, 12 March 1998). Controlling whether BEC atoms attract or repel will help researchers to test theoretical ideas about BECs and understand chemical reactions and collisions in ultracold gases. In addition, the researchers developed an all-optical trap for BECs rather than the magnetic fields previously used (Physical Review Letters, 9 March 1998). This in itself is an advantage because (1) researchers now have the chance to create BECs of atoms that don't respond to magnetic fields, and (2) a laser beam can control atoms to a high degree, for example by guiding them down a hollow optical fiber (Update 245). Once produced in just 3 laboratories in the US, BECs have now been created in Germany (2 labs), and 4 additional labs in the US. (See Georgia Southern University's BEC Page)