# What makes us move in time? [duplicate]

Time is considered to be a dimension, and we are moving at certain rate in one direction in time. What force makes us move in time? I mean it must be ether time moving or us moving in time so there has to be some force that 'pushes'/'pulls'? Was this 'time inertia' acquired during big bang, or nothing is moving and I am just being silly?

• Why do you think any other than the usual forces do this? $F = m\ddot x$ means that your trajectory/worldline is wholly determined if you know the forces acting on you (and your inital conditions). – ACuriousMind Aug 20 '14 at 14:18
• We exist at multiple spacetime positions. Our memories are only able to contain those moments in chronological past of any given moment due to preservation of causality. But the "movement" through time is really no more than us experiencing the sum of our memories in addition to our current existence as time itself progresses and we experience each of the spacetime positions we exist at – Jim Aug 20 '14 at 14:20
• @ACuriousMind I don't. I simply do not understand how it works. I mean if time is moving something must have produced this motion? Or not? – Matas Vaitkevicius Aug 20 '14 at 14:20
• @JohnRennie not a duplicate really - the other question is talking does time exist, and that it might be seen change relative to where you are looking from. My question however is about how come time goes? and what made it go? not does it exist. – Matas Vaitkevicius Aug 20 '14 at 14:26
• A footnote: It turns out from the chat that the question is really about the cause of the arrow of time. – John Rennie Aug 20 '14 at 15:31

Take a landscape. It can be modeled by a function f(x,y,z). If all the derivatives, df/dx, df/dy, df/dz are zero, the landscape is flat to infinity and nothing interesting exists in the landscape.

If one of the derivatives is different than zero, then we perceive a shape, and generally a landscape has a shape. As an example, suppose that we have a cone for this landscape, and there exists a funny "life" that exists in the distance from the center of the cone . All in one snapshot for us, birth is at the cone, middle age is some distance and death is where f is zero.

In a similar manner we can think of time for each of us as starting at birth making a four dimensional shape and ending at death. Another life form will see us as I explain in the example with the cone. Thus time as a dimension for human perception is a df/dt. If nothing changed, there would be an uninteresting landscape .

Now we have developed means of studying what at first is a fourth dimension time axis, because all matter exists and has a df/dt in the four dimensional space. We have concluded from our observations that time has an arrow, i.e. one cannot "move" in the negative direction, from observing how nature behaves thermodynamically and microscopically. Entropy always increases , and that defines an arrow of time independent of the human perception.

The "motion" of time is the motion of our perception. When we look at a three dimensional landscape we can perceive it from zero to infinity. The landscape is not moving. With time we are at a specific time=t_0 sequentially and the four dimensional landscape opens to our perception in slices ultimately controlled by the rate of increase in entropy in our surroundings. The "force" is the usual statistical mechanics and quantum statistical mechanics that rules the nature of matter.

What makes heat move from hot to cold? Entropy. How can you calculate entropy microscopically? Start counting states!

What makes the universe change irreversibly from yesterday to tomorrow? Start counting states!