Taking Carl Sagan's example from "Cosmos", if you accelerate at 1 g for 10 years and then slow down for 10 years you'll find yourself 30,000 light years away from Earth in the center of the galaxy. Dividing the distance you measure back to Earth by your clock you will find you travelled 1500 times faster than the speed of light. Any photons that left at the same time as you will be 20 light years ahead of you, making you perceive they travelled faster than light, and people on Earth will think you took 30,020 years to travel that distance. Earth will be 30,020 older while you're only 20 years older.
Physicists do not use this simple division that truck drivers use because it gives a speed faster than light. But what's wrong with it? They will divide the distance light travels by the time it takes, but they will not let you use the same math for yourself. They say if you race a photon of light you must allow it to change its energy, which means it is a different photon. Isn't that cheating? They also say light goes at 3E8 meters/second for ALL observers moving at ANY speed relative to each other, but this means everything with mass is moving at ZERO meters/seconds relative to light. You can't go faster than light by their methods because your speed relative to light is forced by their definition to be ZERO. If an object is accelerated it is not distinguishable if the object or Universe were the one accelerated to a new velocity. The universe can say the object was accelerated and had a mass increase that looks like kinetic energy, but equally true from the object's view is that the Universe was accelerated and had the same percent mass and energy increase in the external Universe.
The "contradictions" are because "speed" is not a physical quantity. Any reference to "speed" immediately generates needed complexity in violation of Occam's razor in order to hide the use of a non-physical quantity.
"Speed" is not like time, distance, and mass that you can measure. It is a division of one unit by another that are physically the exact same units with a mathematical difference. Speed is unitless because in relativity c is a conversion factor from seconds to meters or vice versa, specifically:
meters = i*c*seconds
(see Einstein's "Relativity" appendix 2). "i" is the math concept "sqrt(-1)".
This equation means the "speed" of light is
c meters/second = i*c*seconds/seconds = i*c
where c is the number 3E8 without any units. We talk about 4D space-time because length and time are not fundamentally different except for the math factor "i". It is mathematical difference, not a physical one. The "i" being carried around in the units is used in physics only in quantum gravity theories and a few other places, but I think it should be used everywhere.
There is a simple resolution to the problem. Relativity is derived from two simple statements:
1) the speed of light is the same for all observers
2) gravity and acceleration are the same force
But a different pair of statements can give the same results:
1) the ratio of meters/seconds changes for all observers
2) mass is like 3 photons "reflecting" in a small volume, perpendicular to each other, 1 for each 3D of space. Mass might be a 4D Euclidean
The 2nd postulates above are needed only for general relativity, not discussions about speed. The added benefit of this second method (besides removing the double-talk) is that if all observer's recognize the effect their frame of reference is having on the ratio, then there is no change in time, length, mass, or the energy of photons. The only thing that changes is the ratio. Instead of using (v/c)^2 in the Lorentz equation sqrt(1- (v/c)^2 ) you call it a change in c based on the v of the observer or gravity. So it's the same math.
Light's speed from its own point of view is infinity (if the limit exits) because it is inifinite time from dilation divided by zero length from contraction. No time passes and distance is infinitely contracted in the direction of travel, so the Universe appears as a flat plane of infinite energy perpendicular to the direction of travel.
The more reasonable and understandable view of relativity is that gravity and acceleration increase the seconds/meters ratio rather than saying the speed of light is a constant for all observers. Mathematically it is the same thing, but it resolves the problem of every observer's speed being zero and photons changing energy in mid-flight. Not allowing them to change energy requires their "speed" (the ratio) to be the thing changing. This can be used to derive the changes the observer sees in length, time, and mass. Mass in relativity not only contorts local space-time by changing the seconds/meter ratio, but can be viewed as sourced from a contortion of the space-time 4D volume, very much like a weightless fork of some kind (charge+spin+nuclear forces) stuck in a net and twisted, adding "mass" from the net to the fork area and tension to the local area of the net that decreases with distance. Letting the net unravel releases energy. The parallel of 4D space-time as the new "ether" is more applicable if you view gravity as changing the seconds/meters ratio instead of saying "speed of light is always constant" which directly violates the concept of a 3D spatial ether. The change in c I am talking about is from the "stretching" of each of the 3 strands of time/space. Instead of saying c is absolutely constant and causes mass, length, and time to change. I am saying only c is changing which allows mass, energy, space-time, and entropy to all be conserved as viewed from all frames of references.
It is c^2 in E=mc^2 because the change in the time/length ratio causes 1D of time and 1D space to offset each other when you calculate the "volume of 4D space-time" that the mass is "made up of", but the ratio still affects the other 2D of space, so the meters/second conversion factor "c" is squared. Again this is not mathematically different, but a different view. To explain better and to take a more traditional view: imagine mass to be photons running around in a tight sphere or better yet 3 of them reflecting back and forth inside, 1 for each space dimension. You expand time relative to length and it affects the perceived energy of the photons in all 3 directions. Their length shortens relative to the time, so 1 time is long and 3 distances are short. But when calculating the 4D volume time only counts once, and it is offset by one of the space dimensions. The other two dimensions are the source of the c^2 factor. Traditionally you use the Lorentz square root function to adjust the mass, but what I'm saying is that you should use the square of a linear change in c which is a lot simpler, and it maintains a negative sign from the "i^2" that cosmology uses for E = -1*mc^2. Obviously there is a difference between energy and mass just as there is between time and length, even as it's claimed "they are the same". The difference between mass and energy is -1 from keeping the i^2 in the units.
Instead of F=ma combined with F12=-F21 as newton's 2nd and 3rd laws to enforce conservation of force and therefore energy and momentum, you get F+ma=0 by not losing the "i" in the units. Again, Occam's razor insists on this method of letting "c" change. When you sit in a rolling chair and push against the wall, the force you perceive is the direction of what you feel from the wall. The reaction is the acceleration of the universe in the opposite direction because by relativity, you have no mass increase from your perspective and therefore no kinetic energy increase, but you do see the mass increase in the rest of the Universe.
This change in unitless c is not observable in other physical constants that have units, so don't believe people who include c (or kb) as one of the constants that can only change if other constants change.
The expansion of the Universe is more simply viewed as an increase in the length/time ratio as the universe gets older. The length expansion of the Universe is the opposite of the time expansion of gravity. As far as can be measured, they are equal and opposite such that it can't be determined if the Universe will collapse or continue to expand forever. This methodology seems to predicts this.
Mass in my view is then proportional to the "enravelled" volume of 4D space-time and does not change from any frame of reference that adjusts for changes in c. If an observer accelerates he should take into account the c of the rest of the universe decreased. In effect, there is no E and mass in this view, but just enravelled space-time and the changes in c it causes.
The distribution of c variations is something that changes if the particle distributions change. This changes entropy while E and m will not change for any observers undergoing any reference frame change. Entropy will also not be a function of the reference frame. Allowing a changing c makes everything else in the Universe much more stable.
A change in the energy distribution but not total E in a standard volume (as well as a comoving volume) changes the spatial variation in the c ratio which changes the entropy of the volume by changing the surface area calculated by Einstein's excess radius. A black hole collapse is a Universe-wide entropy-neutral event by taking a volume away from the rest of the universe (A/4 entropy decrease) and giving it to the volume occupied by the star before it collapsed (A/4 entropy increase). If this idea is correct, the change in area determined by Einstein's excess radius for the INITIAL star volume before and after collapse should give A/4 minus the initial star's entropy (i.e. that dS/dA=constant for a given E inside a given volume where dA is determined by gravity's excess radius that is determined before and after the change in the distribution of E).
Converting mass to E unravels space-time, throwing a radial volume increase (proportional to the excess radius's area calculation decrease for the mass volume) to the Universe outside the initial volume occupied by the mass. The volume increase increases the entropy of the external universe, decreasing it in the volume previously occupied by the mass. The space-time volume (proportional to an area for the reason above) calculated by excess radius (based on a changing c) and entropy are conserved and have a constant ratio for all volumes determined by the observered surface area instead of by the excess radius. Mass is a concentration of entropy and 4D space-time in a volume.