Hi Cleetus -
The problem is not with gravity or the lack of it. The problem is the way that light behaves as described by Dr Einstein in the Special Theory of Relativity. The speed of light in a vacuum is constant, regardless of the motion of the source or the observer. If you are traveling toward a star at .99 x the speed of light, then the light from that star will still pass you - relative to you - at exactly the speed of light. In the same sense, the light from a star behind you in the same scenario will also pass you at exactly the speed of light - relative to you. This seems counter-intuitive and strange, but it has been demonstrated in laboratories and astronomical observatories countless times over the past century and a half or so. This results in the effects of time dilation and length contraction at near-light speeds that you may have heard being discussed (e.g. the Twin Paradox, where a space traveler ages slower than his stay-at-home brother). These are not illusions nor tricks, they are in fact very real effects. So if the light from a distant source always passes you at the speed of light, then it is impossible to reach a speed where it does not pass you at that speed - in other words, you cannot travel along with the photon. It will always pass you at the same speed, no matter how fast you try to go. In fact, it would theoretically take an infinite amount of energy to achieve that, and there is no way to obtain an infinite amount of energy. The laws of physics as currently understood prevent travel at faster-than-light speeds. That's the way our universe works.
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