fixed waiting till heat death problem

main.c

@@ -31,9 +31,9 @@ void *physics(void *args) {
   universe_t *uni = (universe_t *)args;
   struct timespec ot, ct;
   while (true) {
+    clock_gettime(CLOCK_MONOTONIC, &ct);
     mechanics(uni);
     ot = ct;
-    clock_gettime(CLOCK_MONOTONIC, &ct);
     long long elapsed = timespec_diff_ns(ct, ot);
     long long remaining = TIMESTEP / simx - elapsed;
 
@@ -46,6 +46,7 @@ void *physics(void *args) {
 
     do {
       clock_gettime(CLOCK_MONOTONIC, &ct);
+      printf("Waiting !\n");
     } while (timespec_diff_ns(ct, ot) < TIMESTEP / simx);
   }
 }

mechanics.c

@@ -82,7 +82,6 @@ void mechanics(universe_t* uni){
       body_1 = uni->bodies[i];
       scaled_speed = vec2_scale(&body_1.speed, 1.0 / simx);
       body_1.position = vec2_sum(&body_1.position, &scaled_speed);
-      printf("aaa");
       if (i < uni->num_bodies - 1) {
         for (unsigned int y = i + 1; y < uni->num_bodies; y++) {
           body_2 = uni->bodies[y];