# Simulate(float)

> Simulate physics associated with this PhysicsScene.

## Definition

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

```csharp
public void Simulate(float step)
```

### Parameters

**** (\[float]\(https\://learn.microsoft.com/dotnet/api/system.single)): The time to advance physics by.

### Remarks

Calling this method causes the physics to be simulated over the specified step time.  Only the physics associated with this [PhysicsScene](/engine/6000.0/script-reference/unityengine/physicsscene.md) will be simulated.  If this [PhysicsScene](/engine/6000.0/script-reference/unityengine/physicsscene.md) is not the default physics Scene (see [Physics.defaultPhysicsScene](/engine/6000.0/script-reference/unityengine/physics/defaultphysicsscene.md)) then it is associated with a specific [Scene](/engine/6000.0/script-reference/unityeditor/searchservice/scene.md) and as such, only components added to that [Scene](/engine/6000.0/script-reference/unityeditor/searchservice/scene.md) are affected when running the simulation.

If you pass framerate-dependent step values (such as [Time.deltaTime](/engine/6000.0/script-reference/unityengine/time/deltatime.md)) to the physics engine, your simulation will be less deterministic because of the unpredictable fluctuations in framerate that can arise. To achieve more deterministic physics results, you should pass a fixed step value to [PhysicsScene.Simulate](/engine/6000.0/script-reference/unityengine/physicsscene/simulate.md) every time you call it.

You can call [PhysicsScene.Simulate](/engine/6000.0/script-reference/unityengine/physicsscene/simulate.md) in the Editor outside of play mode however caution is advised as this will cause the simulation to move GameObject that have a [Rigidbody](/engine/6000.0/script-reference/unityengine/rigidbody.md) component attached.  When simulating in the Editor outside of play mode, a full simulation occurs for all physics components including [Rigidbody](/engine/6000.0/script-reference/unityengine/rigidbody.md), [Collider](/engine/6000.0/script-reference/unityengine/collider.md) and [Joint](/engine/6000.0/script-reference/unityengine/joint.md) including the generation of contacts however contacts are not reported via the standard script callbacks.  This is a safety measure to prevent allowing callbacks to delete objects in the Scene which would not be an undoable operation. Here is an example of a basic simulation that implements what's being done in the automatic simulation mode.

```csharp
using UnityEngine;
using UnityEngine.SceneManagement;

public class MultiScenePhysics : MonoBehaviour
{
    private Scene extraScene;

    public void Start()
    {
        // First create an extra scene with local physics
        extraScene = SceneManager.CreateScene("Scene", new CreateSceneParameters(LocalPhysicsMode.Physics3D));

        // Mark the scene active, so that all the new GameObjects end up in the newly created scene
        SceneManager.SetActiveScene(extraScene);

        PopulateExtraSceneWithObjects();
    }

    public void FixedUpdate()
    {
        // All of the non-default physics scenes need to be simulated manually
        var physicsScene = extraScene.GetPhysicsScene();
        physicsScene.Simulate(Time.fixedDeltaTime);
    }

    public void PopulateExtraSceneWithObjects()
    {
        // Create GameObjects for physics simulation
        var sphere = GameObject.CreatePrimitive(PrimitiveType.Sphere);
        sphere.AddComponent<Rigidbody>();
        sphere.transform.position = Vector3.up * 4;
    }
}
```

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