When you time travel, do you alter the time for all of universe or just the spot were you are?

When considering time travel, the question of whether it affects the entire universe or just the local area depends on the theoretical framework used. Here are some perspectives:

Time Dilation and Relativity

According to Einstein's theory of relativity, time dilation occurs when an object moves at high speeds or is placed in a strong gravitational field. This causes time to pass differently for the object relative to a stationary observer. For example, if you were to travel close to the speed of light or orbit a black hole, time would pass more slowly for you compared to someone on Earth. However, this effect is localized to your frame of reference and does not alter the flow of time for the rest of the universe25.

Closed Timelike Curves (CTCs)

In theories involving closed timelike curves, which allow for potential backward time travel, the impact on the universe is more complex. Some theories suggest that any attempts to change the past would be self-consistent and not alter the course of events, as the universe would adjust to maintain consistency. This means that even if you were to travel back in time, you would not be able to change significant events, and the timeline would remain intact3.

The Block Universe Theory

The block universe theory posits that all moments in time exist simultaneously in a four-dimensional spacetime. According to this view, time travel would not alter the timeline but rather allow you to move through pre-existing points in spacetime. This theory suggests that every event, past, present, and future, is already set and unchangeable, so time travel would not affect the overall timeline of the universe4.

In summary, time travel, if it were possible, would likely have localized effects based on the observer's frame of reference rather than altering the entire universe's timeline. However, the exact nature of these effects depends on the specific theoretical model being considered.