# B Time and Superposition

1. Mar 18, 2017

### Rachel Lee Pierce

Has anyone considered the possibility that the passing of time is simply the rate of observation of particles collapsing from superposition? And once collapsed, then this is what we understand as the Past, while those still in a probabilistic state is what we understand as the Future?

2. Mar 18, 2017

### PeroK

All particles at all times are in a superposition of states. A measurement (often) changes the state, but it doesn't collapse it in some special irreversible way.

3. Mar 18, 2017

### Rachel Lee Pierce

Can you elaborate or back that up?

4. Mar 18, 2017

### PeroK

A particle's state is essentially a vector. And, any vector can be expressed in any basis. You might say that something like the vector $(1, 0, 0)$ is special because it can be expressed as a single vector in the normal basis. Whereas the vector $(1, 1, 0)$ is the linear combination (superposition) of two basis vectors: $(1, 1, 0) = (1, 0, 0) + (0, 1, 0)$.

But, if we look at these vectors in a different basis, then either or both are a linear combination of the basis vectors.

For example, if we take the simple vertical force of gravity, we can decompose it into the linear combination (superposition) of a force normal to an angled surface and a force tangential to the surface.

So, is gravity a single vertical vector or is it the linear combination of two other vectors? The answer is that at all times gravity has an infinite number of decompositions as a linear combination of any number of forces.

The same is true for the state of a particle. It is always a single state and a linear combination (superposition) of the states of any basis. Sometimes a state coincides with an important basis state (like an energy eigenstate) and that makes it physically special. But, it's still a superposition in any other basis other than that of the energy eigenstates.

5. Mar 18, 2017

### Rachel Lee Pierce

Ok, but since time is relative to the observer then couldn't it still hold true that Now is the observation of the collapsed state? And is there anything to say that the probability doesn't change with each observation, giving definition to our personal pasts?

6. Mar 18, 2017

### PeroK

If you're here to learn about QM then fine. If you want to impose your own woolly ideas on QM, then your thead will probably get locked.

7. Mar 18, 2017

### Rachel Lee Pierce

Great. Thanks.

8. Mar 18, 2017