What's wrong? Says "Physics does not contain a definition for Raycast".

using UnityEngine; using System.Collections; [RequireComponent(typeof(BoxCollider))] public class Physics : MonoBehaviour { public LayerMask collisionmask;

 private BoxCollider collider;
 private Vector3 s;
 private Vector3 c;

 private float skin = .005f;

 [HideInInspector]
 public bool grounded;

 Ray ray;
 RaycastHit hit;

 void Start()
 {
     collider = GetComponent<BoxCollider> ();
     s = collider.size;
     c = collider.center;
 }

 public void move(Vector2 moveamount)
 {
     float deltax = moveamount.x;
     float deltay = moveamount.y;
     Vector2 p = transform.position;

     for (int i=0; i<=3; i ++) 
     {
         float dir = Mathf.Sign (deltay);
         float x = (p.x + c.x - s.x/2) + s.x/2 * i;
         float y = p.y + c.y + s.y/2 *dir;

         ray = new Ray(new Vector2(x,y), new Vector2(0,dir));

         if(Physics.Raycast(ray, out hit,Mathf.Abs(deltay), collisionmask))
         {
             float dst= Vector3.Distance(ray.origin, hit.point);

             if(dst>skin)
             {
                 deltay = -dst + skin;
             }

             else
             {
                 deltay=0;
             }

             grounded = true;
             break;
         }

     }

     Vector2 finaltransform= new Vector2(deltax, deltay);

     transform.Translate (finaltransform);
 }

}