The phrase "a force that exists" is correct and usable in written English.
You can use it when discussing a concept, phenomenon, or entity that has a tangible or intangible presence or influence.
Example: "In the realm of physics, gravity is a force that exists, affecting all objects with mass."
Alternatives: "an existing force" or "a present force".
And though some have wondered at the advisability of staging so grim and doomy a text in a space that (on a nice day, at least) gets flooded with light, it's in the remit of the theater to give off an elemental force that exists apart from the weather.
They are really an ideological force that exists on the Internet.
I believe in evolution; and as a spiritual person I believe that it is part of a super "intelligent design" by some force that exists well beyond our grasp.
Thought is a vital, living force, the most vital, subtle and irresistible force that exists in universe... caused by the vibration of psychic vital air.
Joining with state and federal agencies, the city has created a counterterrorism committee that goes beyond the longstanding joint terrorism task force that exists between the F.B.I. and the New York Police Department.
It is the powerful but invisible force that exists everywhere and requires some leap of imagination on our part, some effort, to identify.
Finally, and most important, there is a failure by the Republican Party establishment in understanding and paying serious attention to the major grass-roots force that exists with the Tea Party.
These particles carry at least one electronic charge, and they interact with matter primarily through the Coulomb force that exists between the positive charge on the particle and the negative charge on electrons that are part of the absorber material.
The meniscus surface force that exists while imaging in air is another strong attractive force.
It might sound strange, but the process of creating her felt largely instinctual, like there was a guiding creative force that existed beyond me.
