As those of you who read my blog know, I have a lot of interests. I may have a mild form of adult ADD. ;) This leads me to a point that I've been kicking around in my head regarding gravity. What if mass does not create gravity but is simply affected by it? I have been studying the problem for a while now and have found quite a bit of work supporting this theory. One of the simpler supporting arguments was called out by Peter Dunn in July of 2003:

If gravity were simply generated by mass certain solar phenomena, ie the solar wind and coronal mass ejections, would not occur. This is why. The escape velocity required for an object (spacecraft - whatever) to break free of the Earth's gravitational embrace is 6.94 miles per second. Now the Sun's mass has been calculated at 333,400 times that of the Earth's so to calculate the corresponding escape velocity for the Sun we can simply multiply 6.94 by 333,400 which gives a speed of two million, three hundred and thirteen thousand, seven hundred and ninety six miles per second or, to put it another way, an impossible to achieve velocity that is a shade under twelve and a half times the speed of light. Material (in the form of the solar wind: calculated at 400mps, and coronal mass ejections: calculated at 600mps) is, however, streaming outward from the Sun all the time. Some might argue that this material does not really escape the Sun's gravity as it forms the heliosphere but, come on, a gravitational field of such intensity would not allow material to be thrown out beyond Mercury's orbit let alone Pluto's.

So what is gravity? In a traditional since it is the force of attraction between massive particles due to their mass. We can write things like F=G(m1m2)/r^2 to describe its behavior but that still does not adequately answer the question. Einstein takes us a bit further with his theory of general relativity where he states that gravity is a curvature of space-time due to the presence of mass or energy. Hmmm. It's obvious now right? String theory may be moving us closer to an answer, but there are still many questions, in many dimensions, to be answered using this model.

Right here in Milwaukee, UWM's Bruce Allen is conducting interesting gravity research with projects like LIGO (Laser Interferometer Gravitational Wave Observatory). The basis of LIGO is that it will detect space-time curvature ripples caused by large moving masses. LIGO (read Bruce Allen) has developed a free program Einstein@Home (like Seti@Home) to "help search our galaxy for undiscovered neutron stars." Maybe the results of the project will yield some more insight into the true nature of gravity...stay tuned.