A House committee approved a plan to build the world's largest atom smasher, a $4.4-billion super collider avidly sought by 25 states. The 38-6 vote by the House Space, Science and Technology Committee was the first step toward a commitment by Congress to build the superconducting collider. So far, it has approved research money but refused to allot money toward construction. The collider would be the largest and most expensive scientific device ever built, an underground ring of 10,000 super magnets 53 miles in circumference and able to whirl protons at nearly the speed of light. The bill authorizes the collider for three years and says about $1 billion can be spent on it.