Why is it not possible that gravity is BOTH an attractive AND repulsive force at the same time?

Question

I have developed a very detailed model of gravitation that suggests this is the case.

Answer 1

Before I get to the original questions, I'm going to address the previous answers.

First, antimatter's existence has been confirmed by experiment many times. For example, a well known antimatter counterpart to the electron is the positron. When two such particles collide, they give off tremondous energy in the form of gamma rays (very, very energetic light). However, antimatter does not have negative mass. So far, no particles with negative mass have been discovered. To explore the subject further, I recommend this helpful wiki:

http://en.wikipedia.org/wiki/Negative_mass

Second, Einstein did have much experimental confirmation when he released his paper on relativity (if he had any at all). The ideas were quite controversial at the time. However, he did have a mathematical framework to support his ideas, which helped with their confirmation later on.

The topic of 'repulsive gravity' has been hotly debated since it was discovered that the universe is expanding at an accelerating rate. Physicsits don't know why this is happening, so they've proposed a theoretical 'dark energy' to explain the expansion. Some people believe that dark energy might be linked to gravity, but it has yet to be proven how.

However, the effects of dark energy are experienced on a universal scale, whereas we experience gravity on a planet-sized scale. The simplest way I can answer the OP's question is to say, "because no one has observed gravity having a repulsive effect."

Another way to think about gravity is by comparing it to other forces, as one answerer compared it to magnetism (which has always been very confusing for me). The force of electricity, for example, allows for positive and negative charge. In that case, like charges repel and opposite charges attract. However, gravity has no "negative charge," or negative mass, as we discussed earlier. Technically, it could be possible, but it has yet to be discovered.

Answer 2

Actually, we have found antimatter in high energy collitions. And anti-matter does not carry a repulsive gravitational force, it is simply the opposite charge of its accosiated particle.

ie. a positron (anit-electron) is the same as an electron, but with a positive charge.

as to the question, its possible that gravity is both an attractive and repulsive force, however we dont know at this point. All we know is that we have never observed such a force... or maybe we have.

Recent stellar data has shown that the expantion rate of the universe is accelerating. This requires a force to be applied, perhaps this force is the repulsive end of gravity? This would require a region of space with negative pressure, this would, theoretically, provide a repulsive force.

Answer 3

because we haven't found anything called antimatter yet, which is what would be needed for gravitational repulsion.

in magnetics, opposites attract because it's like velcro, the hook goes in the loop.

However, in gravitational forces, it's simply everything attacts itself, rules of positive attracting negative are inverted, so positive attract positive, however if we could find a negative mass then indeed they would repel and thus we would get gravitational repulsion.

Answer 4

well first id like to know the phenomenon or event you're trying to explain with this model. it sounds whacky but ummm... well einstien crapped too. but he had experimental evidence. do you have any? id sure like to see your detailed model.