whats the best theory for harnessing gravity to use as a?

Question

propulsion system to propel anything like a spaceship, a car, or a time machine?

Answer 1

They use gravity all the time to send vehicles into deep space with limited fuel availability and even back to Eath from the Moon. This works by approaching a planet and allowing the vehicle to be caught in its gravity, picking up speed and being "slingshot" in the desired direction.

Answer 2

Well, the theory goes that you have to "trick" gravity acting on the front part of your craft as though it were larger than it is, then on the back part of your craft like it was much smaller. The resultant gravity flux pulls the craft forward as though it were falling towards a heavy object without being pulled in the opposite direction with equal force.
Gravity, itself does not push, it only pulls, so you would have to center the focus of the drive towards the front part of the craft (or be able to turn it in any direction).

As far as time travel... not with any kind of "real" physics. However, Einstein did theorize about wormholes in space that could possibly lead to different times due to the relative nature of the universe. If, for example, you traveled to a star that is twenty light-years away in only one year, then you would have essentially gone ninteen years into the past. Because from your new vantage point, the light that reaches you from Earth began ninteen years ago. This would have seemed like you have gone faster than light, but you may have just found a shortcut.

Answer 3

So far we haven't got a clue how to control gravity. For what it's worth, I'm fairly sure that within a few decades, we'll learn how to turn it on and off. Then, for instance, we'll be able to subject spacecraft to thousands of g acceleration without squashing the crew. Einstein's Principle of Equivalence says that simulated gravity in an accelerating vehicle has the same effect as the gravity of a planet. To travel to the stars we'll need to travel at near the speed of light. And if you do the sums, it takes about a year at 1g acceleration to get close. We'll need to find a way round that to travel to even the nearest stars in a reasonable time.

Answer 4

I'm not sure what you want, but they have found a way to generate a force like gravity on a space station by having it rotate around the earth. The centrifugal force generated causes there to be a gravity like force keeping you and items on the ground. But I think you mean more like the gravity gun from half-life as far as I know we do not have a theory for this.

Answer 5

Anti-matter. Selectrons, sprotons, sneutrons, squarks, smeons, etc.

Answer 6

Enter a soap box derby.
(Sorry, but that is the best theory.)