In article , lid
says...

On 2/07/2012 10:43 PM, Jeff Findley wrote:
In article 529ee44e-f348-4443-a0fa-
, says...

On Jul 2, 7:59 am, Alan Erskine wrote:
On 2/07/2012 9:06 PM, bob haller wrote:



We have been broadcasting our presence by radio and tv for how many
years?

not only would ETs know we exist, but lots about our actions Wars
etc.........

i wonder how far the futherest radion waves have traveled by now?

putting it another way, if we were the ETS would we want to go meet
people liker ourselves?

As has been said many times before, the signals we have been sending out
are very low power and therefore very short range. It wouldn't even
reach the nearest star outside our solar system.

thats assuming the ETs receivers are no better than our own........

It's all of the background noise that would be a problem. Even if they
could amplify the signal, they'd also amplify the background noise.

Physics. Learn some.

With a suitable (this is big directional) antenna, they can achieve a
sufficient signal to noise ratio.

There are limits to this. The orbit of the earth limits how far away
from the sun our transmissions can be. Add to that fact that the sun
outputs electromagnetic radiation, and you've got the beginnings of the
problem the ET's would need to solve. They're antenna would need to be
*very* directional indeed to mask the output of our sun while searching
for transmissions from any planets in our solar system.

However, the more directional the antenna, the more difficult it is to
pick anything up by chance.

I'm not a radio telescope expert, but there must be a hard limit,
imposed by physics, to how far away the ET's could be and still be able
to pick out our faint signal while masking our sun's emissions. By
astronomical standards, that limit certainly won't be very far.

"Space," says Douglas Adams' The Hitchhiker's Guide to the Galaxy, "Is
big. Really big. You just won't believe how vastly hugely mind-
bogglingly big it is. I mean, you might think it's a long walk down the
road to the chemist, but that's just peanuts to space."

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker