<div dir="ltr"><br><br><div class="gmail_quote">2009/8/24 Shachar Shemesh <span dir="ltr"><<a href="mailto:shachar@shemesh.biz">shachar@shemesh.biz</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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Michael Vasiliev wrote:
<blockquote type="cite">
<pre>The power of the signal is inversely proportional to the square of
distance.</pre>
</blockquote></div>
That is not precisely accurate.<br>
<br>
An undirected point source of EM radiation (or any other type of
energy) transmits energy that expands on a sphere from the point of
transmittal. The surface area of the sphere expands proportionally to
R^2. Therefor, the law of conservation of energy dictates that the
energy received over a constant area receiver (say, a 1 cm^2 energy
receiver) will decline proportionally to the square of the distance
from the transmitter.<br>
<br>
As a side note - does that prove that our universe only has three
dimensions?</div></blockquote><div>it would if :<br>1. the origin of the signal is a point in all dimensions (which is usualy not true as you transmit continusly in the time dimension(but may transmit a pulse), dunno about other possible dimensions)<br>
2. it is omnidirectional in all dimensions (which is not true either in the time dimension, dunno about other dimensions as well) <br><br>AFAIK, according to general relativity, the world is 4D.<br>according to string theory, there are more dimensions ...<br>
<br>erez.<br><br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div dir="ltr" bgcolor="#ffffff" text="#000000"><br>
<br>
However, if our transmitter is directional, and you keep the
transmitter beam focused, so that it does not expand, there is no
reason for the energy to almost not discard at all. Of course, the
medium through which you transmit the energy may absorb some of it
(assuming it is not a vacuum), and it may disperse some more of it, but
there is no reason to get 1/R^2, or even 1/R.<br>
<br>
Shachar<br>
<pre cols="72">--
Shachar Shemesh
Lingnu Open Source Consulting Ltd.
<a href="http://www.lingnu.com" target="_blank">http://www.lingnu.com</a>
</pre>
</div>
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