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);
   }
 }