In theory when a radio wave goes off in to space, it just keeps going. But,
it decreases in intensity at the inverse square law factor. This means that
it gets exponentially weaker by inverse square law per unit distance. There
would be a point where the strength of the radio wave would be as weak or
weaker than the natural full spectrum of the background noise radiation that
exists in space. At this point, it would not be easily detectable.

As for the standard long wave, medium wave, and short wave communications,
most of the energy from these bounces off the ionosphere back to the earth
again. They keep going in their path until they disperse or wear down to a
level that is no longer detectable. There has been some experiments were a
radio wave pulse was sent out in a single direction, and about a half a
second later it was picked up again from the opposite direction. This radio
wave travelled around the world, bouncing between the ionosphere and the
earths surface.

VHF, UHF, and higher frequencies can escape the ionosphere and go out in to
space. There are scientists and even some hobbyists with a descent budget
who have experimented in bouncing radio waves off the moon for research.
This requires some specialized equipment and knowledge to implement, and
work with.

As for receiving radio waves coming back from out in space that have been
sent from the earth is another thing. There are some theories and people who
have claimed this to be. There is the theory that the wave may go out
somewhere, and bounce off some type of planet or object that can amplify it
in some manner. This is only speculative, and there are some theories that
support this.

There have been a few claims of people getting both radio and TV signals a
few days or even a month or so after its broadcast. I can recall reading
about a case that in about 1954 there was a family in Newfoundland that
claimed to have picked up a TV station from Florida that was broadcasted
about 8 days prior. The Florida TV station did say that they did not repeat
this program in any way at that time. There is no actual proof of this
other than the descriptions of the people who claimed this to be. They said
that the picture was very snowy, but was able to be made out along with the
sound. It supposedly only lasted about 3 minutes or so.

There have been actual documented cases where TV stations have been picked
up over excessively very long distances. But these were normal broadcasts,
and were not delayed out of the ordinary. By some chance there was a skip
effect caused by the ionosphere. The reception conditions were ideal at that
time.

There is speculation in this case, was that some of the family members may
have been to Florida, or a friend of their who has been, was over at their
place at the time. They may have picked up some distant station from the US
at the time, which is most likely possible, and thought they were watching
an older program. It is possible that the program that was on TV was a
similar program to what they thought they were watching.

From the background that I have in engineering, I personally cannot see in
practice a broadcast signal going far out in space and then returning even a
few minutes later. Then again, I am not authority in this type of
phenomenon. I can see this able to be done over a few seconds by beaming
the signal to a close body in space such as the moon, if directly intended
for this type of purpose, using the proper set-up, resources, and equipment
to do this. In theory if they can do this to mars, then it would be a few
minutes. But, one would have to be a dead on aim to do this, because the
reflected signal would be very critical, and the bodies are moving in space.
Considering the power required, and the losses involved, I cannot see in
practice to reflect a signal off of anything much farther than the moon.

Then again, in theory a signal that goes out in space should have that very
small chance of reflecting back to the earth. But, being able to sustain any
reception of it, or even make it out any intelligence in it, would be
another matter.

This is my personal opinion only...

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================


"Current_gothic" wrote in message
...
Just think what if this actually happened
maybe it has to a few of you, or maybe it hasen't
some may see this as a troll or a joke. but actually it isin't
i was thinking about this today and was wondering what the rest of u
on here might say..
so here it goes.

Have you ever thought to your self. or known some one who maybe has,
heard strange singnals. now i dont mean number stations, or odd BCB
stations. i mean like have u ever sat spinning the dials on ur radio
and then all of the sudden heard something odd that wasen't from this
ear. ur probably thinking ok get to what ur talking about

well what i mean is maybe a airplane sent off a message over shortwave
radio lets say back in 1940 and maybe just now from 1990 on to 2004
maybe u heard the message over ur radio , and found out it was from a
plane or something else in a back farther date over shortwave.

now i mean its a weird phenomenom (bad spelling) but can it happen .
or maybe it has happened to you,,

would like to hear your input

thanks

The Wizard (channels 19,11,27,35..on the CB)
VE3010SWL-Professional shortwave listener
NAMA1380-Professional scanner operator

Keep your heads up high but your antennas up higher