I think once we are advanced enough to figure out how to propel anything that fast or able to pack the needed energy, this part might be easy to solve.
Remember per special relativity mass increases as we approach C.
Also I think there will be other physiological problems while accelerating to C. It would take like 34 days at 10g acceleration to get to C. I wonder how our bodies would handle 34 days at that kind of g limits. At 2g it will take like 173 days to reach C.
Lastly, we don't really have a good physical understanding of matter at near C speed limits. With mass increasing as we approach C, I don't know we can assume the same physical properties of any material in classical models.
> Lastly, we don't really have a good physical understanding of matter at near C speed limits. With mass increasing as we approach C, I don't know we can assume the same physical properties of any material in classical models.
Yes, we do, and yes, we can. Matter travelling at near c relative to us behaves exactly the same as any other matter. That's what frame invariance means. From our perspective, yes, the ship would seem to have more mass, which is a direct result of the equivalence of mass and energy and the fact that it has a crap-tonne of kinetic energy. But from the ship's own perspective, its mass does not change at all- rather, the entire surrounding universe seems to become more massive.
Sure! My reasoning was why add 2 years just to accelerate and decelerate. And as I said, "once we are advanced enough to figure out how to propel anything that fast or able to pack the needed energy" there were other challenges to overcome.
First, people on the ship will not feel as if they "have more mass". Their physical properties will be exactly identical, because they are at rest in their frame of reference. Flying through a galaxy at 0.999c is identical to "sitting still" while a galaxy flies by at 0.999c.
Second, you're ignoring relativistic effects in your calculation of the amount of time it takes to "reach c". You can't just divide light speed by the acceleration and convert to days. You need to include the effects of time and space dilation, in which case you'll find you have to pick a target less than c because no matter how long you accelerate you only approach c.
>>Flying through a galaxy at 0.999c is identical to "sitting still" while a galaxy flies by at 0.999c.spaceship.
You're right if you were sitting in a train and watched the station go by, but not at .999c. You're ignoring relativistic mass.
Unlike General Relativity where we were able to measure the effects of sun's gravity against the position of emitted light from the stars, The truth is we have no empirical evidence of the effects on solid objects (not single accelerated particles) approaching C.
The summary of the article mentions that, in the mass' frame of reference, relativistic mass is the same as rest mass:
> As seen from the center of momentum frame, the relativistic mass is also the invariant [rest] mass [...]
Actually, the whole idea of relativistic mass is misleading to intuition. It makes more sense to think of relativistic energy. This is mentioned near the end of the article:
> Many contemporary authors such as Taylor and Wheeler avoid using the concept of relativistic mass altogether:
>
> > "The concept of "relativistic mass" is subject to misunderstanding. That's why we don't use it. First, it applies the name mass - belonging to the magnitude of a 4-vector - to a very different concept, the time component of a 4-vector. Second, it makes increase of energy of an object with velocity or momentum appear to be connected with some change in internal structure of the object. In reality, the increase of energy with velocity originates not in the object but in the geometric properties of spacetime itself."[6]
Remember: the laws of physics are invariant with respect to absolute velocity. If you add 5 m/s along some direction to all velocities, all the same interactions will occur. Relativity does not break this invariant.
Remember per special relativity mass increases as we approach C. Also I think there will be other physiological problems while accelerating to C. It would take like 34 days at 10g acceleration to get to C. I wonder how our bodies would handle 34 days at that kind of g limits. At 2g it will take like 173 days to reach C.
Lastly, we don't really have a good physical understanding of matter at near C speed limits. With mass increasing as we approach C, I don't know we can assume the same physical properties of any material in classical models.