We know that the speed of an object is always relative to something else that we consider at rest(a point of reference).
If we have a totaly empty universe, save for one object (nothing to use as a point of reference). Obviously the upper limit of light speed for that object still applies. But how can we tell if the object has reached light speed when there is nothing for reference? Is there an absolute (instead of relative) speed?
If we have no point of reference, then we can only assume the object is still. We can only know about acceleration, which can be “felt” by the object, but traveling at a constant velocity is exactly the same as standing still.
If there really is only a single object, then the speed of that object is not a well-defined quantity. That is, speed is fundamentally relative.
However, if you were there to observe this object, there would be two objects (you and it), and you could then talk about the object’s speed relative to you.
But who would you talk to? 
Are you confusing point(s) of reference with a FRAME of reference.
Early determinations of the speed of light were made between mountain tops, hence the earth was the frame of reference.
The speed of light = 299 792 458 m / s. It a a CONSTANT according to Physics.
Light and all electromagnetic radiation travel at this speed.
PS A single point in an otherwise empty universe is a point of reference.
(Non-physics guy here)
Slight highjack:
What if your huge space vehicle was traveling 299 792 457 m/s (almost the speed of light).
You would be standing still inside this vehicle for it is your FRAME of reference.
But if you (inside) were to move forward from the aft to the bow (rear to the front) at a high rate of speed, say half of the speed of light.
From an external frame of reference would be traveling faster than light. I thought that was impossible. :dubious:
I am sure someone more inclined in the art of physics can answer this more appropriately, but no, you do not exceed the speed of light. If you were going at 99% of the speed of light, you get to 99.9% of the speed of light or something like that. I don’t remember all of the details, but it has to do with time and distance stretching or contracting. If I wasn’t at work I could get out my modern physics book and really explain it well.
And if no one gets to it by the time I get home, I will do just that.
If you’re in a ship moving with 99 of the speed of light, and you’re moving along the ship at half the speed of light, your relative velocity as seen by an outside observer cannot exceed the speed of light.
This is highly non-intuitive, since it’s common to just add the two velocities to get the relative speed that a non-moving observer would see. The “adding velocities” method is called the Galilean transformation, and it worked out just fine until the discovery that the speed of light is measured to be the same in all frames of reference. An inevitable consequence of the speed of light being see as the same everywhere, no matter how fast you’re going, is that asking how fast someone else sees you going becomes more complicated than just adding together all the velocities. The result is that changing to someone else’s frame of reference requires a Lorentz transformation, for which no object can exceed the speed of light. Here is a link to the exact formula for velocity additions using this method.
The exact derivation of the Lorentz transformations from the fact that the speed of light is the same in all reference frames is a bit more complicated and may be more information that you’re looking for, but I’m sure that’s available on the web as well.
[QUOTE=Procyon]
If you’re in a ship moving with 99 of the speed of light, and you’re moving along the ship at half the speed of light, your relative velocity as seen by an outside observer cannot exceed the speed of light.
QUOTE]
If we cannot “observe, see, perceive, witness, or watch” it, could we still calculate it?
Picture the ship again.
From the observer’s perspective the person disappeared and reappeared.
Perhaps the outside observer would see the person at the end of the ship vanish and reappear at the front? Could we then gather the data (distance traveled and time from the start and stop) and determine a speed faster than the speed of light?
Thinking along the lines of: the person inside the ship was never “observed” exceeding the speed of the light, but it was calculated that he had.
That reminds me of the police on the overpasses timing cars as the pass between bridges.
“Sir, you never “observed” me speeding, you are trusting your mathematics to reveal my true speed. My friend Pasta says “speed is fundamentally relative.” And my other friend FlippyFly says “you do not exceed the speed of 65 mph (the speed limit). If you were going at 99% of the 65mph(the speed limit), I could never get to 99.9% of 65 mph(the speed limit)”
Ok that was kinda stupid, but my limited intellect has a hard time understanding “You cannot exceed the speed of light”, but I’ll keep listening, reading and learning.
:smack: 
Speed is not strictly additive in circumstances like this – there’s a complex formula relating the relative velocities to the constant C, which amounts to something like 60% of C + 60% of C results in 95% of C, not the expected 120%.
Ugh, I don’t have time to give the explanation that this requires… but the problem is that the speed of light is constant (and a maximum), while both distance and time are not constant. In other words, to an observer on the ship the person would take less time to reach the front than he did to an observer on the ground.
Oh, so now we must contend with “time travel”. Yeah this is getting pretty messy, I think I should jump out of this thread before I annoy the OP by continuously re-directing the responses with my questions. Every response makes me want to ask more questions.
(What if Tidus casted Haste 8 on the person on the ship (Lulu) and Slow on the observer Sin?) <–disregard that question–< 
Reading this article leads me to question the whole idea of the speed of light as a constant…
http://physicsweb.org/article/news/7/7/9
My favorite sentence from this article: “Negative speeds indicate superluminal velocities because the pulses appear to leave the crystal before they enter it under these conditions.” Ahhh! What the heck?
I’m slightly nerdy, but not nearly nerdy enough to understand this.
Here’s Cecil’s column on the subject of addition of relativistic velocities.
And here’s a Wikipedia article that says basically the same things as Cecil.
As I recall my cosmology classes 25 years ago, there is actually a specific meaningful reference frame in the universe that is distinct from any particular object in it. We know that objects that are more distant are also receeding faster, relative to more nearby objects. This amounts to speed = some constant times distance. You can build an average this way, which of course is also receeding at great distances - but we here on earth have a velocity relative to that, which includes the Milky Way drifting through space, and us orbiting its center, and on and on. This reference frame is expanding but over sufficiently large distance scales object velocities with respect to this frame have a distribution that is random in some sense with mean = 0.
I think you could locate this reference frame without objects per se if you were allowed to do experiments starting with the big bang. But you can definitely locate it, and astronomers have, by observing objects as they are today. This is a framework against which movement of galaxies can be compared.