Recently scientists were amazed that the space probes now leaving our solar system suddenly started to speed up? They should not be surprised because the gravity from the sun pulls in material from around our solar system and then compacts it. Just like our atmosphere is more concentrated closer in. On celestial bodies in our own solar system we know there are layers of various density as your travel closer and closer.

http://hypertextbook.com/facts/1997/PatricePean.shtml

Once you reach the outer limits of the solar system the material will be less dense and thus easier to travel thru. Similar to flying and airplane underwater as the water is 640 times more dense than the air. If deep space is similar in this regard then in fact as your reach the outer limits of the solar system it will become less and less dense and eventually extremely thin and thus easier to travel thru. Lets say for instance in the solar system the space has 10 molecules per square meter and as you leave the solar system there is 1 molecule per square meter? Other places 1 atom per square meter. The actual amount has been hypothesized and determined but for explanation of the issue the exact amount is somewhat irrelevant, let the folks at NASA and JPL figure that out and determine speeds and friction of space craft traveling in deep space. What is important is you understand the basic concept here.

Picture the Solar System as a giant beach ball enclosed under its own gravity. We are inside spinning around its center mass, the Sun. The beach ball is one of many spinning around and floating in deep space within another huge space which is like the inside of a blimp only the size of Earth. The blimp size of the Earth spins around something else and so on, all in perpertual motion. Each level has different density based on its mass and pull on the area around it and the total of the mass of all the celestial bodies in it. All added up together within those spaces (beach balls, blimps, earth size spaces, etc and so on).

The reason scientists are so surprised is they have not thought this thru correctly and rely on theories born of hundreds of years back. Each theory trying to stay with the scientific realm of the past theories and only advancing incrementally even though the new data shows somewhat differently. Science often screws things up because it is too early to poo poo ideas and theories and too quick to adopt other theories into Laws or facts due to their ability to nicely fit with past theories and laws of past periods, like stacking Lincoln Logs, Legos or building an erector set. The problem with this is that if your foundation of knowledge is incorrect, no matter what you place on top of it is to no avail, since you started with the wrong concept of your original building block. For instance stacking turtles on top of each other to hold up the world as Steven Hawkins reminded us in one of his books or the thought that the world is flat and that the Earth is the center of the solar system and you get the point. \

We keeping making laws of physics and then finding we break them and then make new laws. Yet we are so quick to make laws that we fail to understand the whole and how all that relates to the inter-connectedness of all. Einstein tried to figure on a grand unification and never came up with it. Yet surely it must be around here somewhere and it must be something simple and simplicity always breeds complexity. So the formula is something very simple. Never the less we have some rethinking to do with this new discovery that the space ships speed up once they leave the solar system and we should not be the least surprised that they do. We are not surprised when a Polaris Missile is shot out of a submarine under water and breaks the surface of the water and immediately accelerates to Mach 3 going straight up. We are not surprised when aircraft travel faster in higher altitudes where the air is less dense? We are not surprised the amount of energy it takes to break free of the Earths atmosphere? We therefore should not be surprised that the space probes leaving the solar system speed up. Actually we should have been surprised if they didnt. Think about it?