What's the secret behind v < c

With massless particles v = c

There is no philosophical principle. It is science. If you want to understand this, you will get yourself to a college and start taking math and science classes.

v is a variable, c is not.

You say something true and meaningful in physics, so, I reply.

c is variable.
It is based on an average of measurements taken from multiple institutes every decade.

We're only talking billionth's - But No 2 equate.

And the 'field' of measurement is never the same 'field' - Nor is the 'measuring' aparatus.

wrong, because the meter has an international agreement of length, the speed of light has been ASSIGNED and is called a UNIVERSAL CONSTANT.
(Speed of light is the v attained by light's travel in a vacuum for a fixed amount of time over a fixed distance (Its not a second either). Its not a frequently derived constant like the HUbble or the "radioactive decay constant"

If v is variable, then c must be constant.

This science mullarky's not so hard after all.

Interesting...somewhat alike philosophy.

When objects move in velocity v < c, their matter states do not change. You remain you, electron remains electron, etc.
When something moves in velocity of c, it will be released photon only. The matter state of released photon is obviously different from you, electron, etc…
The traditional 3D space SR contains a hidden condition: matter state does not change. (Actually, the so called “rest frame” or “moving frame” is attached to substantial object.) That’s why v < c is the premise of traditional 3D space SR.
When people use SR to analyze space – time transformation, etc, concerning released photon, an element denoting matter state should be added. Moreover, anti matter, dark matter, etc, are different matter states…The traditional 3D space SR should be expanded with the element denoting matter states and then it will be sufficient to represent cosmos.
With regard to the question of “light speed in photon frame”, I think that the traditional Lorentz transformation of speed is not applicable anymore because the observer and released photon are in different matter states. People have to find another way to do that.

As a former Physics teacher, I would like to make the standard disclaimer.

There is no actual Physics, or valid science of any kind, being discussed on this thread.

Now back to your scheduled, very odd, programming.

Actually, you are talking something in physics too. But I don't see what physical meaning exists if a particle without the most basic element: mass. Non existence?
Why the concept of "massless particle" appears in physics? I think it's due to certain method of description by people. That method can not describe the mass of some particles does not equal to those particles without mass in nature.
For example, we all know that a pig has a long nose. But people can't draw it out on a paper with the front view. If people change a method of description, from the side view, the long nose will appear on the paper...

Dear:
I always admire teachers although I was a very bad student in school 20 plus years ago. I liked sleeping and drinking when I was in university while did no homework...really bad... If you want to know how bad I am now, turn to physicshelpforum.com...quantum physics column or special and general relativity column. Surprising "bad" is in the lounge column...my username there is neila9876
Regard.

Actually, you are talking something related to physics too. Physics can not exclude experiment as well as observation, right? I feel hard to reply you, really. Perharps one sentence: we are what we measure while nature is not us...

It sounds like you are suggesting that massless particles don't exist, and that our perception of masslessness is just an illusion of our limited ability to describe a particle... is that correct?

This might be of help: https://en.wikipedia.org/wiki/Massless_particle

I mean: any method of description is limited ability...haha
The true help in this respect might be the thread 0 = 0? below...haha

@no one:
We had some "odd" discussions in the thread "The attraction of massless particles to other massless particles..." in the nuclear and particle physics column of physicshelpforum.com.
(老猪阴囊里的粒子很珍贵，不是用来对付在座各位的。。。用来扫射他江门地方黑恶势力钟永康，可以一颗不留)

I didn't understand any of that.

You didn't understand that, but you had no problem with the Chinese?

That's well weird.

Even if I understood Chinese, I probably still wouldn't understand it.