R Kym Horsell wrote:
Photons have no mass.
Observed or measured speed in any inertial frame will always be c .
For any remaining hillbilly parrots that dont know what they are
c is the speed of light in a vacuum.
But there is more than one kind of vacuum.
The vacuum most scientists mean is the standard vaccum where the
speed of a photon is c.
The speed of light in a medium is whatever it is. Many are slower
than c. The refractive index tells you how much slower.
(The change in speed of photons as they enter a medium defines the
angle of refraction and hence the RI).
The standard vacuum has an RI of 1.00000000000.
But the standard vacuum runs at the "zero point energy" where
virtual particules pop in and out of existence at high speed.
On balance the vacuum is "essentially" empty. But that doesnt mean
Some of the virtual particles are electron/positron pairs. These
come in and out of existence in pairs and keep the electric charge
balanced. After a small time (~Plank time interval) they mutally
anahilate again. And it goes on and on.
These electrons do have an effect. They make the RI of the vacuum 1.0000.
But if you can create a vacumm with "less energy than 0" you can
decrease the RI to below 1 and the speed of light in that kind of
vacuum can be measured as faster than c.
In at least 1995 (op cit) this has been done.
Hillbillies will continue to quote from 100 year old high school
dulled-down-for-100-IQ-everyman science textbooks because they
are parrots and do not actually understand anything.
It's all covered in Incompetence Theory.
Kruger and Dunning argue that for a given skill, incompetent people will:
1. tend to overestimate their own level of skill;
2. fail to recognize genuine skill in others;
3. fail to recognize the extremity of their inadequacy;
4. recognize and acknowledge their own previous lack of skill, only if
they can be trained to substantially improve [their own performance].
Dunning later drew an analogy with anosognosia in which a person who
suffers a physical disability because of brain injury seems unaware of
or denies the existence of the disability, even for dramatic
impairments such as blindness or paralysis.
Dunning & Kruger & others concluded that the root cause is that, in
contrast to high performers, "poor performers do not learn from
feedback suggesting a need to improve".
-- Ehrlinger, Joyce; Johnson, Kerri; Banner, Matthew; Dunning, David;
Kruger, Justin (2008). "Why the unskilled are unawa Further
explorations of (absent) self-insight among the incompetent".
Organizational Behavior and Human Decision Processes 105 (105): 98-121.