The way it is

Speed

If I claim that time is a non-thing, then our thoughts turn to speed. We specify speed as distance travelled, divided by the time taken. Miles per day, kilometres per hour, metres per second. Distance per number of oscillations in the clock. Note that indicated speed depends on whether the clock is moving with the object or being held by a stationary observer. When an object moves, its distance relative to all other objects changes. Two objects on the same path can have differing rates of relative distance change. That rate of relative distance change is speed. Time does not come into it. In other words, something can be moving twice as fast as something else, because the rate of relative distance change is double the other. Oscillations in the clock are not absolute. They vary depending on the motion of the clock. Speed is a comparison not a value. A multiple of relative distance change compared with other objects.

I am sure someone, somewhere, at some point tried to contest a speeding ticket using the claim that the car was travelling at minus 550 miles per hour rather than 50. That would be the case at a certain latitude where the Earth rotates at 600 miles per hour. Speed is relative. There is no definitive speed, but a range of speeds in relation to various points of reference. Your speed in relation to the sun is quite different to the speed in relation to the moon. Clocks placed on different planets will not display the same rate of internal oscillations compared with each other. What we consider to be this point in time, now, is not a fixed point. Now is in constant motion. Yesterday is only an idea. We think of it as where everything was positioned relative to one another previously. There is no back in time, but how things were - the state of things before they all moved. However, there is no record of where every atom was positioned previously. Tomorrow never comes, because when every tomorrow comes that tomorrow becomes today. I will plagiarise a promise; you can have jam yesterday or tomorrow but never today. Believing in tomorrow will leave you salivating but never eating.

The entropy factor ensures that we are unable to put everything back to how it was. A time traveling machine needs to make time a thing first. Then adjust every atom in the entire universe in a way that runs counter to what makes it work in the first place.