Why didn't search party get affected after McCoy altered past?

Question

In ST:TOS 1x28, the USS Enterprise followed time ripples to their source from millions of miles. McCoy injected himself a drug by accident and beamed down to the planet in an out-of-control situation.

Kirk, Spock and 4 more crew members also beamed down to search McCoy. On the planet's surface, they found an intelligent entity (The Guardian of Forever) which apparently was the source of the time ripples. It was a time and dimension portal. Suddenly, McCoy jumped into that to go to the Earth's past.

Instantaneously, the Enterprise went out of existence. They concluded that McCoy changed something critical in the past which undid all Enterprise-level technological achievements of humanity.

Provided, Enterprise didn't exist, how did the search party exist on that planet? Without the Enterprise, they would never have been able to trek to the planet.

I am not concerned about McCoy's existence because it's a paradox. I am asking why the crew wasn't wiped from existence.

Answer 1

The Guardian of Forever is seemingly a sentient being, able to control the time portal to some extent (such as when it pulled Kirk, Spock, and McCoy back at the end of the episode).

To borrow from its description on Memory Alpha:

It is apparently sentient, responding to external stimulus such as questions and actions, and can even somehow control the flow of time. It generates immense ripples in time that manifest themselves as spatial disturbances in the region around the planet where it is located.

This would seem to imply that the Guardian is actually preventing the time ripples from affecting the planet or anything on it. Orbit, however, seems to be fair game.

Likewise, after McCoy goes through, the Guardian comments:

"All that you knew is gone."

That further implies that the Guardian intentionally protected Kirk/etc so that they had a chance to restore the timeline.

Answer 2

It is an accepted part of temporal paradox tropes that objects in the center or near the center of the cause of the transformation/alteration of the timeline are "protected" from the affect at the "eye of the temporal storm."

In light of the power of the Guardian of Forever, its ability to distort space and time would have to have a central region that remained free of its ability to affect circumstances outside its local space and time. Otherwise it might be able to erase itself. (Granted, what kind of time portal would the Guardian be if he could potentially erase himself from existence?) But that didn't sound possible at any rate, the Guardian made it sound as if it had always existed and would always exist. "I am my own beginning and my own ending."

The fact the Guardian could show an event which could then cause the entire Federation to cease to exist makes the Guardian the most potent and dangerous objects in Federation space, if one knew how to use it.

Since these ARE stories, such temporal loopholes allow the other characters to remain in existence to try and right the wrongs and put things back the way they were, before the alteration. The challenge in those stories is figuring out what went wrong and determining how to put things back the way they were.

The episode referenced is: "The City on the Edge of Forever." The penultimate episode of the first season of the television series Star Trek. It is episode #28, production #28, first broadcast on April 6, 1967.

Answer 3

Wibbly-wobbly, timey-wimey stuff. The planet they beamed down to belonged to the Guardian of Forever which controlled the time vortex. The entity itself and its immediate surroundings are immune to time effects. Otherwise it would contradict its own existence. It makes sense to assume it exists in some kind of envelope outside of normal time and space. I would interpret this as being independent from the rest of the universe.