Actually, it should be; "If they don't have mass how come they don't travel at the speed of light?"
First is that they always travel slower than "C" the speed of light.
Second is the mass is virtual. We might consider it to be 0+j1.
Remember that while the photon is are right angles to the gravitational field it is effected by it. Yet when aligned on the same axis as the motion of the photon it doesn't "accelerate it".
I'm not sure if it is correct to say that a photon gains or looses this virtual mass as if falls down a gravitational well.
Actually, the human eye can't detect single photons. They're not that sensitiveSecond: If it is now "They're carriers of mass or was that force?". If a wave, then what hits the eye?
It's known (as far as the tools we have!), that the human eye can detect 1 (ONE), photon.
There are devices like PMT's which can detect single photons, and even... "half photons". Ha, you're going to say that doesn't make sense ! And you'd be right, but... this is the world of quantum physics, half of a photon can be in either of two places
What is detected by the eye is... Both. depending on how you look at it, so to speak. The answer you seek is described by "Photo Electrics".
That appears to be the case with respect to the planck constant.2a) If it has energy then it has to have mass, no?
I'm not aware of any other particles known to have a zero mass.
[quote]And what about these Neutrinos - now found out that they have mass?[quote]
Yes they have mass. I learnt in high school that it was suspected they were massless and that photons had a rest mass. It's the neutrinos that have a rest mass and photons do not.
Neutrinos are the carrier of the weak nuclear force. Changing the neutrino flux can change how fast isotopes decay.
Dunno, but I sure as hell don't have a firm grasp on it. The best thing I can suggest is that if you're prepared to constantly change your thinking it helps a little. Usually you will find two experiments to test a theory which oppose each other, yet both hold true. Like the double slit experiment we are all shown in high school.Who said (might have been Feynman), "If you can explain Quantum Mechanics, then you don't understand Quantum Mechanics".
Actually, I keep an eye on the second hand book shops. Some good books turn up from time to time. I just finished reading an old one I found from 1955.... 2,476,873 are from Trashes IP...
It's quite interesting how it talks about the apollo missions in the future tense.
It has lectures from a number of professors (including Julius Sumner-Miller) on a variety of subjects. One of the subjects is cosmology, and it describes dark energy and universal expansion with some amusing clarity without even realising what it is they are describing.
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