# Are the ideas of the speed of light and the absolute top speed inside the universe equivalent? [duplicate]

The idea of the speed of light being as fast as something can go is pretty well accepted. I'm wondering if the top speed might be (very slightly) higher? Lemme explain.

I was reading about particle acceleration, and how accelerating a particle to the speed of light would require infinite energy.

According to a quick Google search, the LHC is getting particles up to 0.999999991 c. For someone such as myself, I might as well consider that the speed of light. I mean, it's so close, right?

So what if in a similar vein, the speed of light is very, very close to the absolute top speed? Is that possible?

If the speed of light in a vacuum was something like 0.9999999999999999999999999999999999 to the absolute top speed in the universe, would we ever know the difference? (this number is just an example to show how the speed of light could be imperceptibly close to the absolute top speed, and yet still not be the fastest speed possible).

• Seems like a duplicate of this, perhaps, and/or probably several other questions on this site. Jul 16, 2014 at 3:32
• MGaz: "what if the speed of light is something like 0.9999999999999999999999999999999999 to the absolute top speed in the universe." -- Speed of light (in vacuum), a.k.a. signal front speed is exactly 1.0 to the absolute top speed (of any thing/signal being exchanged; not to be confused with "phase speed" etc.) due to the definition of what we mean by (how to measure) "speed" (and "light") in the first place. Related: "Is the Speed of Light an universal spacetime constant ... ?" and many more Jul 16, 2014 at 3:34
• Note that the LHC does not hold the record for human-created particle beam speed. That distinction belongs to LEP if you count beams in collider systems or some high energy neutrino beam or another in the unlimited open division. Jul 16, 2014 at 4:20
• I think the problem with this question is - this really is two separate questions. 1. The question in the title, for which everyone can answer YES, as per the current understanding. 2. The question in the body "What if c is slightly lower than the absolute maximum speed", which will certainly involve opinion-based answers and hence, may be closed by the moderators. @MGaz - you may want to edit out your question and be more specific about what exactly you want to ask. Also, take precaution so that it doesn't get closed as a duplicate of the Q that David Z mentioned. Jul 16, 2014 at 5:47
• I don't think you should flag my question as a duplicate of one that was closed for being unclear/poorly asked. As I understand it, those questions are supposed to be re-asked. Jul 16, 2014 at 12:51