(need to know the concept of entropy and homeostasis, and the previous principles of MCU)
When you travel forward in time - in the sense of changing the present as if the configuration of planets, people, the state of knowledge, memory is as in the future (taking information from an alternative line that has already developed to this point in the future), and only keep yourself unchanged - then the state of the amount of information cannot change, so it will be a state containing an anomaly, because entropy must proceed at its own pace, it can't be jumped, delayed or accelerated, when you increase entropy, then with the help of cosmological force, there will be an equalization of the state of the amount of information, so either something will spontaneously decay ("increase" entropy, and actually return to the level of entropy from before the anomaly), or spontaneously appear (as an aside, it can sometimes look like some traveler from an alternative timeline appeared in our line). so you will be the anomaly when you are "in the future", so something will spontaneously arise, because in the state in the future the amount of information is less, and yet there is still the present, so there must come from somewhere (a cosmological force, but nevertheless based on the principles of physics, quantum spontaneity) some portion of information to be as much as there must be in the present.
When you "go back in time," that is, modify the present so that it is in a state from the past, but keeping yourself ("time traveler") from the present, in turn, something must spontaneously begin to disappear (including perhaps yourself), because in the present the amount of information is less, and this must even out.
In practice, a local "reversal in time" can occur without loss, at the expense of global entropy - locally, the amount of information remains the same, but there is more information, so we maintain balance.
Equilibrium is always restored with some inertia, in a fluctuating manner, according to the principles of homeostasis, so and traveling back and forth in time, there will be spontaneous appearance and disappearance of things (information, structures), until a state of equilibrium is reached, then the fluctuations will stop.
This is not something that occurs only with "time travel", when, as part of the normal (consistent with the progression of entropy) destroy something, then the amount of information decreases, so the result will also be the spontaneous emergence of information "somewhere else" to restore equilibrium.
PS I made this up a while ago.
