Aliens trying to take over world!

[K.I.L.E.R]

http://www.chron.com/disp/story.mpl/nation/3795387.html

This is very scary.
We could be invaded by an alien culture anytime soon.
We need to place nuclear weapons into space.

 

[nintenho]

"Sending laser signals across the cosmos would be a very logical way for E.T. to reach out, but until now, we have been ill-equipped to receive any such signal," he said.

......hot topic is not punk rock........

 

[The_Wolf_Who_Cried_Boy]

Aliens using lasers to communicate..

 

[StefanS]

Aliens using lasers to communicate..

Don't run away, we're friends

 

[Rolf N]

Pure bs.

Sending laser signals across the cosmos would be a very logical way for E.T. to reach out

No, it wouldn't.
Just another well-funded research project that will go nowhere. In ten years everyone will deny ever being involved with it. And in fifteen years the same project will be started again.

I think it could rock to be in this kind of research, i.e. you can make a living without ever being productive, and you know it beforehand.

 

[KimB]

We'd never pick up a random laser transmission. The only ones that would make sense for us to pick up would be transmissions that were directed at us. Since pretty much the only way any other civilization should know about us would be through our own radio tranmissions, they can't be more than about 60-80 light years out to know we're here, and I would tend to think that SETI would have ruled out that possibility by now.

 

[K.I.L.E.R]

How could SETI have ruled it out?
All they do is try to find exotic radio signals.

We'd never pick up a random laser transmission. The only ones that would make sense for us to pick up would be transmissions that were directed at us. Since pretty much the only way any other civilization should know about us would be through our own radio tranmissions, they can't be more than about 60-80 light years out to know we're here, and I would tend to think that SETI would have ruled out that possibility by now.

 

[Rolf N]

How could SETI have ruled it out?
All they do is try to find exotic radio signals.

A laser is by definition a bundle of parallel coherent photon goodness. It doesn't spread out. Virtually all natural light sources do, most "civilization" light sources do (if they're not lasers, that is), and radio transmissions do, too.
A laser with a 1cm radius at the emitter will cover a spot with the same 1cm radius when it hits earth, even if it travelled half the universe. Thus if "E.T." doesn't aim directly at that telescope, there's no way we'll receive a laser signal. Even aiming roughly at the earth will not suffice. That's the whole stupidity of the program.

SETI OTOH tries to catch signals that spread out as they travel, and that's exactly the reason why SETI could find something.

 

[Rolf N]

Aliens using lasers to communicate..

The guys who funded this probably saw too many images of that sort. A laser is not visible if not scattered by dust or aimed directly onto your retina.
(I know you weren't serious; I just thought it was worth saying it)

 

[RussSchultz]

A laser is by definition a bundle of parallel coherent photon goodness. It doesn't spread out.

http://en.wikipedia.org/wiki/Laser

Not quite.

 

[pax]

I wonder if this could detect those accelerated light particles that have already been tested to be possible.

Id rather see seti invest in tech that could detect faster that light speed comms... Like maybe the entangled particles idea...

 

[KimB]

I wonder if this could detect those accelerated light particles that have already been tested to be possible.

Id rather see seti invest in tech that could detect faster that light speed comms... Like maybe the entangled particles idea...

Well, since we don't know of any possible faster than light communications technologies, it's rather impossible to detect them.

 

[pax]

Didnt they have detectors in those lab experiments? I had read that a few experiments had already done it up to as fast a 300 times the speed of normal light... I was hoping this was cheap enough tech that seti could afford hhe...

 

[KimB]

Didnt they have detectors in those lab experiments? I had read that a few experiments had already done it up to as fast a 300 times the speed of normal light... I was hoping this was cheap enough tech that seti could afford hhe...

Well, from what I understand the important aspect of this transmission isn't what is transmitted, but rather what it is transmitted through. And as such, it just isn't possible to perform the transmission over more than a rather short distance (i.e. you're not going to be able to fill all of space with a gas), and even then I'm not sure that they're actually transmitting faster than the speed of light.

 

[K.I.L.E.R]

Something like that would be well suited for computing.

 

[KimB]

Something like that would be well suited for computing.

I don't think it'd be any more useful than fiber optic transmission.

 

[soylent]

A laser is by definition a bundle of parallel coherent photon goodness. It doesn't spread out. Virtually all natural light sources do, most "civilization" light sources do (if they're not lasers, that is), and radio transmissions do, too.
A laser with a 1cm radius at the emitter will cover a spot with the same 1cm radius when it hits earth, even if it travelled half the universe.

I'm sure there's other considertations too, but the momentum-position version of Heisenberg's uncertainy relation will give you a minimum beam divergence that will decrease inversely with radius. The radius of the laser cavity essentially 'locates' a photon to having passed within a disc-shaped region of the same radius as the beam, this gives you an uncertainty in the momentum perpendicular to the beam.

 

[KimB]

Conversely, this means that any laser beam does widen over distance.