# autoSimulation

> Set whether the physics should be simulated automatically or not.

## Definition

* **Type:** Property
* **Namespace:** [UnityEngine](/engine/6000.0/script-reference/unityengine.md)
* **Assembly:** UnityEngine.Physics2DModule

> **Warning:**
>
> **Removed.** Physics2D.autoSimulation is deprecated. Use Physics2D.simulationMode instead.

```csharp
public static bool autoSimulation { get; set; }
```

### Remarks

By default, physics is updated every [Time.fixedDeltaTime](/engine/6000.0/script-reference/unityengine/time/fixeddeltatime.md) during the play mode. It happens automatically as part of the regular game loop.

However, there are cases where being able to advance physics manually is needed. One particular example example could be networked physics where rewinding time back and applying all the player input is required up on receiving data from the authoritative server.

To control the physics simulation manually, disable the automatic simulation first and then use [Physics2D.Simulate](/engine/6000.0/script-reference/unityengine/physics2d/simulate.md) to advance time. Note that [MonoBehaviour.FixedUpdate()](/engine/6000.0/script-reference/unityengine/monobehaviour/fixedupdate.md) will still be called at the rate defined by [Time.fixedDeltaTime](/engine/6000.0/script-reference/unityengine/time/fixeddeltatime.md), but the physics simulation will no longer be advanced automatically.

Additional Resources: [Physics2D.Simulate](/engine/6000.0/script-reference/unityengine/physics2d/simulate.md).