Most folks know about the speed of light and all of the problems with trying to build a ship that could travel at that speed.
1. As you approach the speed of light the mass of your ship would approach infinity.
2. Time dilation. Even if you were able to build the craft that could do it, from your perspective, you would never process the second or millisecond where you reached the speed of light.
3. It would take an infinite amount of energy to reach the speed of light.
These barriers are the result of Einstein's Theory of Special Relativity. But even Einstein gave us an out when it comes to traveling faster than light. The trick is not to move an object through space. But to move the space the object is in. Einstein's laws say nothing about space itself being moved. So there are models and theories now about how to build a warp bubble, allowing for this type of travel.
But there is also the possibility of constructing or using a wormhole. You could have a path through spacetime that connects two distant points. And the wormhole through spacetime would give you almost instantaneous travel no matter how far away these locations are from each other.
Then lastly, there is teleportation. We could build a device that could analyze a person's body at the planck length of spacetime. Each planck unit could be copied and transported via a form of "entanglement" to a distant location.
But all of this could be moot.
Because of the one thing we have overlooked for decades;
FTL travel breaks casuality.
We could literally break the universe by building a successful FTL ship or simply by building a FTL message system. Consider that if we built a ship and traveled to a distant location. The ship doesn't even FTL capability. Let's just say it went at 90% of the speed of light. If we started off on a distant journey, we would experience time dilation. According to Einstein, our "clock", our time", would tick slower than a person's time here on earth.
Now imagine if a person wanted to send us an instantaneous message using some FTL messaging system. A person could send a message to us, four hours after we left the earth. That's four hours from his/her perspective. We would receive that message approximately two hours into our journey. Actually it would be slightly less.
And here is the important thing. We receive the message two hours into our journey. . .but message is received in the past for the person on earth. Remember, our clock is moving half as fast as a clock on earth. So we could reply. . .and our reply would travel back in time from the perspective of anyone who is still here on earth.
They would receive a reply to a message, that they never sent. Or more accurately have not sent yet. You might say what's the big deal? What if the message says. . ."do not send any messages, it is a matter of life or death".
How could we receive a message that was never sent? And the paradoxes just get worse from there. If you are traveling faster than light, you can go to a distant world and come back before you left. You can cause all manner of nonsense because the rules of casuality do not apply anymore.
Once I read about this, it kind of messed me up. I am a big fan of Star Trek.