It will be useful to deal with Extremely low frequency radio waves..
Hi Siva Prasad Kodukula ,
theoretically, both the group and the phase velocity of inhomogeneous plane (evanescent) waves (surface waves) can be less than c.
There are some experimentally proven phenomena which involve evanescent waves (e. g. Goos-Hänchen effect), and I assume any discrepancy between theory and results would have attracted further attention which it hasn't as far as I know.
In the thesis behind the following link, on waves along a kind of Goubau wire, theoretical and experimental results match well (see chapter 6); the wavelengths are compared which are proportional to the phase velocities:
https://thesis.library.caltech.edu/6597/3/Yeh_c_1962.pdf
With the advent of metamaterials, we can dispersion-engineer synthetic structures to achieve almost any desired phase/group velocities, including imaginary and/or negative values.
However, this is only for guided-wave modes. If you're referring to plane-wave propagation in a vacuum, the medium is dispersionless and therefore all waves propagate at the same rate.
@Joerg Fricke, Thank you Sir.. If necessary I will come back to you...
The reason behind this question is -
"While I am working on consciousness and brain, as per quantum information calculations of my model, I got a conclusion that wave of 10^-6hzfrequency is the main cause to originate consciousness. But as per uncertainty principle the energy of that wave cannotsupport to complete that ossilation. So it will not come out as an electromagnetic wave with velocity 'c'. If its energy is less its frequency will be less but instead of enlarging its wavelength, its velocity will be redused. Combination of such waves(one million waves) produces as 1hz and can get it byEEG. The lesser frequencies if comes out seperately their velocity must be less than 'c'. Itcontains quantum information that will be processed in brain. If right answer is available, it can be used in experimental verifications...
Denis Jaisson
, it depends on the material between inner and outer conductor. Usually, it has a relative permittivity of about 4, and a relative permeability of 1, which results in a velocity of about c / 2.
@Denis Jaisson,.... it is better not to use ignorance like words -"I know that the velocity of em wave depends on permittivity and permeability of medium. That is the reason the velocity is light velocity in vacuum or space. So such low velocity em waves can not exist in this space(you may call it as vacuum). But still there is a possibility of existence of Space with different parameters. Its consequences can be observed and reverse analysis can be done.Such spaces are possible in quantum mechanics and waves related to quantum particles.
@Denis, Thank you for your understanding of the question. I am not interested in argument with you... no.. use...
EM waves can be slowed down enormously, and even stopped, but only in special matter, not in free space. I think it is unlikely that this would happen in the brain. What do you mean by saying that if you combine 10^6 waves of 10^-6Hz you get 1 Hz. This doesn't make sense. You would only get 1 Hz from 10^6 pulses with repetition rate 10^-6 Hz, and to get this the pulses would need to be less than 1 s wide so would contain a wide range of frequencies including frequencies close to 1 Hz. You might (I don't know if it actually could happen) also get it from simultaneous collision and conversion of 10^6 photons to one photon, but if it is possible this is so unlikely to happen it probably won't ever happen anywhere in the life of the universe, let alone in everyone's brains.
If you are talking about space with different parameters, then many things are possible, but there is no evidence for it, and what can happen in it is guesswork.
- Badges
- Science topic