celox

I understand. Then how does a massless particle in motion attain mass? Is that "kind" of mass also an interaction with the Higgs boson (I guess not, since you speak about dynamical mass without the Higgs)? The Higgs boson is a hypothetical particle (I'm reading). Anyway, you're right -- it does make sense that way.

Severian, Exactly what I wanted to know, thank you! I see your point, and why a sub-c speed of light is seen as improbable. However, I personally see the idea of anything moving at c as perhaps equally unbelievable. The same goes for a particle without mass. I know that human logic may not apply -- but as long as there is a possibility, I don't think we should entirely give up on the idea. Well, at least I won't.

I don't know, as I have not thought much about gravity yet. If gravity is a property of space, probably. If it's a result of gravitons, probably not. Indeed. It will be interesting to see if more accurate measurements in the future will show a difference between the two. Definitely something I'll be keeping an eye on -- thanks! Very interesting idea, I'll have to think this over. Thanks again!

Interesting. However, I'm not saying that c depends on the speed of source or observer. I define c as an upper limit -- a constant (just as in SR). I define the speed of photons as seperate from, but very close to, c. I guess the equation would still fail, however. Could the equation simply be an abstraction of a simpler or more complex one, the "real" equation? As I'm not doing away with c as a physical constant, time dilation would still stand. The photon would also be subject to time dilation, as any other particle.

No? Even if EM radiation travel so close to c that we are currently unable to measure a difference? Du you have a pointer or an explanation why this is the case? The difference in the waves would be so tiny, even if the car was driving at supersonic speed or beyond, that there would be no measurable visible/audible/whatever difference. Or is there a reason why something can't be a wave if traveling (slightly) below c? By my understanding, all matter are waves -- or are those waves a different thing altogether?

As in there are no current experimental evidence that would invalidate my theory?

If the photon travels at speed c, yes. However, I think it makes more sense that the photons travels slightly below c (because of the logical problems I outlined in a previous post). No' date=' I'm not. I'm trying to understand things from experimental data, regardless of [i']SR[/i] or any other theories. I wan't to know how possible it is that the speed of light may not be exactly c. I agree, so I question the validity of SR. Which resolution? My speculations are not within the context of SR (only experimental data), and can not be correct if SR is entirely accurate.

I mean speed limit in a relative sense. There is a maximum speed at which something can move relative to us and our measurement of time. When something approach c relative to us, it will require more and more energy to accelerate at the same pace, again relative to us. Eventually it will seem that it's no longer accelerating, because it is so close to c that we are unable to see the difference between c and the moving object. That is how fast I think light might be moving. Hm, I'm not sure you understand what I'm trying to say. Please read some of my other posts above for some clarification (hopefully) of what I'm trying to say.

rajama, No problem, just an indication that I may not have made myself clear enough. Just to clarify further, I'm not talking about a special property of vacuum. I'm talking about the properties of light, and the possibility that they may not be exactly what we think. I here define c as the universal speed limit, and not c as defined by the speed of light (which may or may not be the exact same value).

Sure, but that's not the issue here. The post consens itself with light and photons. There are nobody traveling with the photon, it's simply observed in all the ways we (with current technology and techniques) are able to observe it -- those obervations are my reference frames. I'm not sure I follow... But anyway, no, that's not what I'm talking about.

That's what I thought as well. If anyone disagrees when it comes to the speed of light, I would be interested in hearing about it. I guess, if true, it would/could mean that photons have rest-mass. Let's say that they have for the argument. What would then be the highest rest-mass of photons and the lowest speed of light that current experiments could allow for? Also, if I am correct that it is possible, is it stupid to believe that photons have a tiny amount of rest-mass (as I currently do)? And why is such a belief stupid? I know that physicists say that the photon has no rest-mass, but could that conclusion be premature? I know I'm not "supposed" to put myself in the photons place, but I would like to do so anyway (until anyone provides a good reason why I should not). From the perspective of the photon, if moving at speed c, everything else would be moving at speed infinite. This means that the photon is everywhere at once (and time would not exist?). Now, I don't see how a set amount of energy can be determined for a photon when it's moving at infinite speed (I would think it would have to be zero or infinite). And should not zero rest-mass times anything be zero as well? I know there are other formulas for finding the energy of photons than for something that has rest-mass, but perhaps those exist only because they are mathematically convenient relative to current theories? Another thing: How can infinite speed and "everywhere at once" be divided into chunks, as it must be for light to not travel at infinite speed from our perspective? I mean, infinite divided by a billion would still be infinite... In general I see the "number" infinite as merly a potential, and as something that can probably never occur in reality (other than as a potential). I'm not saying that light can't possible travel at speed c, I'm only saying that it's not logical to me. I'm not saying that reality has to be logical, I'm just saying that I'm more inclined to believe in a logical theory as long as it may possibly be correct -- I find it more...well, logical.

Let me clarify how I define c in my post: I define c as the speed at which (if it were possible) any mass would become infinite. Is it possible that the speed of light (and not c as I defined it) is slightly lower (relatively) than the c I just defined? I'm first and foremost interested to know if it is possible by current experimental data, and not whether SR or any other theories allows for it (as current theories may not be 100% accurate).

Is it possible that the speed of light (in vacuum) is 0.999999999c (or some other number of 9's after zero) rather than 1c? Here I define "c" as the universal "speed limit", and obviously not as the speed of light itself. I know that it would have to be so close to c that we would (at least currently) be unable to measure any difference. But by my understanding, something accelerating very close to c (relative to us) would eventually move fast enought that it would seem to move at c from all reference frames, as far as we would be able to measure it.