Naked Science Forum
General Science => General Science => Topic started by: kikit on 05/04/2006 17:17:23
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I am writing this in the hope that someone can help me with a problem i am having with a short story, well it's not a problem as such, it's just that i hav'nt done the research befor coming up with the ideas[:I] my questions are about waves. My story is dependant on transmitters dotted around the globe which can produce wave that cover the largest are possible (360 degrees) with the least amount of energy needed to produce the waves at the cheapest cost.. so here are my questions
1) My waves have to be able to pass through every type of material (be it biological or artifiacial) that is on the planet, but without causing any harm..so what differant kinds of waves could i use safely?
2) What kind of waves would be dangerous(if any)?
3) the transmitters that produce these waves (transmitter being the right term i hope) have to be a small as possible, and each one much be independantly powered (for the purposes of my story they have to be descreet), so if i wanted A single transmiter (including the power source and other things i will also refer to this as a unit, and i would like each unit to be no bigger than a wardrobe) to be capable of producing waves powerful enough to extend as as far as a city's limits (e.g the transmitter is in the city centre and i want the signal/wave to cover the whole of that city) then what kind of wave would be capable of doing this (could it be something as simple as a sound wave for example)
4) would the independant transmitter need alot of power to produce such a signal?
5) could that power be derived from solar panels that are built onto the unit with the transmiter ( remembering that each individually unit would need to be no larger than a wardrobe)?
6) If the unit was inside a building would that have any effect on how far the wave would travel?
7) If it was inside a building, and was producing this wave would it have any effect on people's televisions or mobile phones ect..
8) Does the production of certain waves require a licence of some kind?
9) I would be most interested about waves that can be generated by without a need for a licence, but either will do.
10) the transmitter units also have to be able to recive signals, would this pose any problems ?
Thankyou for taking the time to read this, i would be very greatfull if anyone could answer any of these questions give any advise
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Information extraction waves are what you are looking for. Find a form and get them to do your research. Better still tell them you are doing it. This will disarm there defiance.
What you do speaks so loudly that I cannot hear what you say.
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First general problem, there is a natural symmetry between a transmitter and a receiver, so that a signal that is easy to transmit is also easy to receive (i.e. to be absorbed by some material), whereas a signal that is difficult to receive (i.e. will pass through most things without losing energy) will also be difficult to transmit.
At it lowest level, neutrinos and gravity waves will pass through most things without any impact (gravity waves are presently more theory than proven fact, since as far as I am aware, they are so difficult to detect that no-one has yet detected one). Unfortunately, neither of these things are particularly easy for us to generate in a controlled fashion.
VLF radio waves will pass through most things to some depth, but will not permeate a metal box, and you really need some very large antennae to broadcast them (in the order of several kilometres in size – but then, the national grid actually does this job very well).
Generally, with the exception of low power output in certain specific frequency bands, the broadcasting of radio waves will always require a home office licence (or its equivalent in other countries). I don't know of any other waves that generally require such a licence, excepting where there is likely to be a hazard to the public.
It should also be noted that low energy radiation will have less information carrying capacity that high energy radiation. Light can carry more information than radio waves, and low frequency radio waves carry less information than high frequency radio waves, and VLF radio waves can carry only an extremely small amount of information.
George
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for whatever it may be worth, radio hams have communicated across the globe on only about 1 watt of power. Presumably this is via Morse code, and using very sensitive receivers. Such a signal is, obviously, effectively undetectable to ordinary equipment, unless rather close by. You should not expect to be able to send with a large information rate using such methods. These waves of course will be blocked by a highly conducting metal box.
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The use of ionizing radiation: Certain forms of ionizing radiation can penetrate rather deeply into matter; but there is the hazard involved, and the question of just how effectively such radiation could be used to carry information. If, however, the level of radiation is very low, say comparable to natural radiactivity, the hazard would be negligible. This of course requires that the number of particles emitted per second be low. This is ordinarily a poor way to carry information; however if one gets into the murky mysteries of quantum mechanics, I do not know but that it may be possible in principle to carry more information on a single particle than we would ordinarily think possible.
A weak radioactivity may be imagined to be difficult to detect against natural background radiation; however if the signal is composed of quanta having certain well defined characteristics (such as the gamma rays emitted from certain specific nuclear transitions), they can, in principle, be selectively detected against other radiations.
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Neutrinos are extremely penetrating, and pose virtually no hazard to anything because they rarely interact with anything. But of course, these properties also make they very difficult to detect. Such experiments as have been done to date using them require large, cumbersome installations.