When we talk about the speed force, a lot of thoughts start racing through your mind. Personally what comes to my mind first is the colour red, and this time we are going to explore why the speed force is almost always accompanied with the main speedster in DC, and who it's limited to.
First off, the Flash. He is a troubled young man with many problems in his life, and when he got struck by the lightning bolt, he gained an awesome power, speed.
Thats right, he didn't have his enhanced healing ability when he first started running, it took him a while, the reason for is that when he took his first step in super speed, he created a paradox, yes, you see whenever something out of the ordinary pops up, and I mean out of the ordinary, like the flash surviving the lightning bolt and gaining powers from it, or time travel like the story line X men days of future past, or age of Ultron, a paradox happens in that universe, something that may rip apart the fabric of reality, so, if there happens to be a paradox, a new universe is created to maintain stability, and when the flash took his out of normal first step in super speed, a paradox was created because humans aren't suppose to move that fast in so little time, and the universe created in response to this universal confusion was the speed force.
It's a parallel universe - as other sources put it - that can be accessed through creating enough kinetic energy to break the dimensional barrier which lies in between, so superman fan boys, sorry but our boy here is just faster, but don't worry, there is another explanation why superman can't access th speed force, we'll get to that later.
Now when the speed force was created by Barry Allen, it was but mere energy floating around it's parameter, it could hardly keep itself from collapsing rather than serve the flash, but as he began to run more and more, it was being fed the energy, so not long after he got his original powers did he gain the ability to heal rapidly, although he did heal faster than the average human being when he first got his powers, it was revealed later on in The Flash Rebirth that his body functioned faster as the speed force grew, faster healing, faster thinking, faster everything.
Considering the flash ( Barry Allen) is the cause of the speed force ever happening, it is fairly well to say that he gets the most out of it, and although he wasn't the first flash, he had more speed then Jay Garrick, making him the beginning of the speed force and not Jay Garrick, Jay could only barely run at the speed of sound before he met Barry, so that means Barry can enter whoever he wants into the speed force, does that mean it is under his command? well, no, because as you will read, there are other characters that entered the speed force without the help of Barry.
Every time we see the flash running, we see little sparks of lightning and stuff, well that's just the speed force powering him up, I should note though, that he is the one using the power from the speed force, and not that the speed force is searching for high velocity objects and attaching to them. but when the flash runs so fast he sometimes gets sucked in to that dimension, now we know that he can exit it if he maintained his speed, but if he loses concentration or trips or anything happens that may slow him down, he could get stuck in there with no way out, meaning it's a risky thing, that is what happens to the reverse flash in The Flash Rebirth, as he gets stuck in there for fifty years.
Of course, over the years Barry Allen does get closer and closer to understanding the speed force, he evolved with it to the current point where he can enter it and exit at will without fear of being trapped, he can grant other speedsters a little more juice so that they can run faster, and he can trap people in the speed force where they can not escape, sometimes forever.
One more thing to mention is that, nowadays the flashes use the speed force as their main source of speed, since they got their speed naturally from it after Barry Allen, we can say that superman or any other fast character who can not enter can't because the speed force is kind of like under the flash's control, since the flash family are who power it up and drain it, they can be said to naturally have it as their main speed force, but superman's speed does not come from it, and as long as Barry Allen is or any other speedster doesn't enter superman into it, he can't access it. we can also say that he isn't fast enough, although he and the flash have raced on several occasions, a lot of them ended up in a tie due to outside circumstances, the flash did beat superman once though in a fair race, which was explained because superman was not use to running at high speeds for long periods of time, which gave the flash an upper hand, go training!
Next time I will talk about the people who are able to enter the speed force, bot not all, only the ones who have a possibility to show up in the T.V show.
Let me know what you thought about my description of the speed force.