With Help From Jodie Foster, SETI Resumes Search for Alien Life(betabeat.com)
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With Help From Jodie Foster, SETI Resumes Search for Alien Life
http://www.betabeat.com/2011/08/16/jodie-foster-funds-seti-2011-08-16/
8 comments
It's a nice gesture by Foster, for sure, but she'd have better used her money on other space projects.
The Alan Array of the Seti Institute will only be of much use if they can build out to 350 Arrays from the current 42. Supporting just $200,000 to keep the 42 operational isn't going to do anything but keep the pretty useless current array working!
Also just so you know SETI @ home doesn't rely on the Allan Array - they're separate.
The SETI Institute was pretty much a boondoggle: Alan gave them money to build an array of 350 telescopes, but they screwed up and only built 42, essentially wasting the funds. Here's other info: http://www.skyandtelescope.com/resources/seti/3304581.html
The Alan Array of the Seti Institute will only be of much use if they can build out to 350 Arrays from the current 42. Supporting just $200,000 to keep the 42 operational isn't going to do anything but keep the pretty useless current array working!
Also just so you know SETI @ home doesn't rely on the Allan Array - they're separate.
The SETI Institute was pretty much a boondoggle: Alan gave them money to build an array of 350 telescopes, but they screwed up and only built 42, essentially wasting the funds. Here's other info: http://www.skyandtelescope.com/resources/seti/3304581.html
We have all those radio telescopes built already. Seems silly for humans to let them sit idle. Even if we don't find aliens I'm sure there is something interesting to see with all that gear.
True. 'Looking' at otherwise empty space can sometimes yield some incredible results: http://en.wikipedia.org/wiki/Hubble_Deep_Field
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Especially considering how relatively cheap they are to operate.
Someone posted the following on the article:
"This's never made sense to me. When you consider the inverse square law for electromagnetic transmission in light of the distances we're talking about, any signal big enough for us to receive would have completely cooked anything at the point of origin."
A quick Wikipedia search says that the inverse square law does apply to radio waves. Can someone that understands this better than I explain why this may or may not apply?
It seems like a total deal killer for the project.
"This's never made sense to me. When you consider the inverse square law for electromagnetic transmission in light of the distances we're talking about, any signal big enough for us to receive would have completely cooked anything at the point of origin."
A quick Wikipedia search says that the inverse square law does apply to radio waves. Can someone that understands this better than I explain why this may or may not apply?
It seems like a total deal killer for the project.
Can someone that understands this better than I explain why this may or may not apply?
That's a good choice of wording :) It may or may not apply, it depends on the antenna.
The physical basis for all inverse square laws - gravity, electrical charge attraction, radio signal strength, is actually geometric. They are all measurements of some kind of flux, so you have a certain quantity of signal, which then has to be divided by the surface area of the sphere surrounding the source. As the distance from the source increases, the surface area of the sphere increases as the square of the radius.
So yes, if the source is in fact a point source radiating equally in all directions, the signal drops off as per the inverse square law. But, if you have a very tight beam, then the signal strength is maintained for a lot longer. In that case, signal loss is caused by diffusion, and by attenuation due to hitting matter that is in the beam. A highly parallel laser beam of a not unreasonable power level, preferably generated from a satellite orbiting outside any atmosphere, should be capable of being received pretty much anywhere in the galaxy. Alternatively, if you have a big enough dish, you could do the same thing with radio waves. Indeed, it is estimated that Arecibo is capable of communicating with any other Arecibo-style dish in a roughly 100 hundred light year diameter around the Earth, if the two happen to be pointed at each other, and one is transmitting whilst the other is receiving... http://www.cplire.ru/html/ra&sr/irm/limitations.html
And that's with a measly 1000kW radio, weaker than most primary radars used today.
That's a good choice of wording :) It may or may not apply, it depends on the antenna.
The physical basis for all inverse square laws - gravity, electrical charge attraction, radio signal strength, is actually geometric. They are all measurements of some kind of flux, so you have a certain quantity of signal, which then has to be divided by the surface area of the sphere surrounding the source. As the distance from the source increases, the surface area of the sphere increases as the square of the radius.
So yes, if the source is in fact a point source radiating equally in all directions, the signal drops off as per the inverse square law. But, if you have a very tight beam, then the signal strength is maintained for a lot longer. In that case, signal loss is caused by diffusion, and by attenuation due to hitting matter that is in the beam. A highly parallel laser beam of a not unreasonable power level, preferably generated from a satellite orbiting outside any atmosphere, should be capable of being received pretty much anywhere in the galaxy. Alternatively, if you have a big enough dish, you could do the same thing with radio waves. Indeed, it is estimated that Arecibo is capable of communicating with any other Arecibo-style dish in a roughly 100 hundred light year diameter around the Earth, if the two happen to be pointed at each other, and one is transmitting whilst the other is receiving... http://www.cplire.ru/html/ra&sr/irm/limitations.html
And that's with a measly 1000kW radio, weaker than most primary radars used today.
http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html In the middle of the table is an interesting chart that shows the distance that radio can be detected. You will notice that for large distance you need terawats of power and a very low band widths, fractions of a Hz. A big TV station doesnt make it out of the Solar System, while a very powerful, low bandwidth, focused source can be detected for hundreds of light years. Unless someone is pointing at us at the same time we are pointing at them, we will probably miss them.
We can detect quasars billions of light years away because they are big mothers, but really hard to modulate, and turned off by now.
We can detect quasars billions of light years away because they are big mothers, but really hard to modulate, and turned off by now.
Here: http://www.seti.org/page.aspx?pid=225
They address this under "No More TV for Aliens". CTRL-F for it.
Also: yes the inverse square law does apply to radio waves.
They address this under "No More TV for Aliens". CTRL-F for it.
Also: yes the inverse square law does apply to radio waves.
Direct link, courtesy of Firebug: http://www.seti.org/page.aspx?pid=225#PC754_dgStories_ctl18_...
A quick Wikipedia search says that the inverse square law does apply to radio waves
I don't understand why not. Aside from the difference in wavelength, there's absolutely no physical difference between radio waves and physical light.
I don't understand why not. Aside from the difference in wavelength, there's absolutely no physical difference between radio waves and physical light.
Considering we can detect radio sources more than 10 billion light years away, I suspect ours can probably be spotted a few tens of thousands away.
I can see the sun from more than 90 million miles away, but that does not mean I can see your flashlight from a few tens of miles away.
With good optics and a vacuum in between, sure you can.
Jodie was already one of my most beloved actresses. Now with this, she climbed to the top of the list.
I have a question: is SETI actually useful?
There's a couple of agencies on Earth that spend their time capturing human communications. It's a very difficult task and they need more than $ 200,000 to operate.
Now I understand we just want to detect with a good degree of certitude that a transmission is intelligent but not human. We don't care about descrambling it.
Yet, I think it's an almost impossible task because those communications will most likely be compressed and ciphered and therefore look like noise.
There's a couple of agencies on Earth that spend their time capturing human communications. It's a very difficult task and they need more than $ 200,000 to operate.
Now I understand we just want to detect with a good degree of certitude that a transmission is intelligent but not human. We don't care about descrambling it.
Yet, I think it's an almost impossible task because those communications will most likely be compressed and ciphered and therefore look like noise.
The article indicated that they didn't raise enough money to actually switch the telescope on. Worth noting.
Fermi Paradox: http://en.wikipedia.org/wiki/Fermi_paradox
It's even more relevant if what we're searching for are civilisations that are 'similar' to ours, ie use radio/electro-magnetism for communication at a distance
It's even more relevant if what we're searching for are civilisations that are 'similar' to ours, ie use radio/electro-magnetism for communication at a distance
I don't see how the Fermi paradox is relevant or helpful in any way. What you fail to understand is how large our galaxy (never mind the Universe) is and what time frames we are talking about. Grasp this:
1) The Milky Way Galaxy contains an estimated 200–400 billion stars. Let's assume that humans build a machine that can check if a star has life around it in only one second.
Now, to check one billion stars for life you would have to wait 31 years, which would be reasonable, but to check 200 billion stars you would need roughly 6000 years.
The observable Universe contains 3 to 100 × 10^22 stars (about 80 billion galaxies). You do the math how long it would take to check just a tiny, tiny fraction of that number, assuming you would have such a machine, capable of giving an answer per second.
2) The Universe is about 13 billion years old. Life on Earth is an estimated 3 billion years old. Humans, as they look today, appeared about 200000 years ago. Humans developed means of communication with other civilizations only 50-100 years ago.
What exactly do you hope to discover in a timespan that can't even qualify as a bleep on the Universe's radar? The evolution of humans is not synchronized to the evolution of other forms of life. Humans (or any other form of life in the Universe, for that matter) can go extinct without warning. It would take a long time for our radio waves to reach another civilization and the other way around, and by the time they reach their destination the intended receivers may be long gone.
TL/DR - the Universe is huge, and very, very old. Don't underestimate the difficulty of finding life.
1) The Milky Way Galaxy contains an estimated 200–400 billion stars. Let's assume that humans build a machine that can check if a star has life around it in only one second.
Now, to check one billion stars for life you would have to wait 31 years, which would be reasonable, but to check 200 billion stars you would need roughly 6000 years.
The observable Universe contains 3 to 100 × 10^22 stars (about 80 billion galaxies). You do the math how long it would take to check just a tiny, tiny fraction of that number, assuming you would have such a machine, capable of giving an answer per second.
2) The Universe is about 13 billion years old. Life on Earth is an estimated 3 billion years old. Humans, as they look today, appeared about 200000 years ago. Humans developed means of communication with other civilizations only 50-100 years ago.
What exactly do you hope to discover in a timespan that can't even qualify as a bleep on the Universe's radar? The evolution of humans is not synchronized to the evolution of other forms of life. Humans (or any other form of life in the Universe, for that matter) can go extinct without warning. It would take a long time for our radio waves to reach another civilization and the other way around, and by the time they reach their destination the intended receivers may be long gone.
TL/DR - the Universe is huge, and very, very old. Don't underestimate the difficulty of finding life.
So, in a discussion about finding alien life, you don't think the Fermi Paradox is relevant, OK.
Your condescending response is amusing, but also demonstrates that you've failed to understand what the Fermi Paradox. I would humbly suggest that you read up on it at the Wikipedia page, as most of your objections are dealt with there.
Your condescending response is amusing, but also demonstrates that you've failed to understand what the Fermi Paradox. I would humbly suggest that you read up on it at the Wikipedia page, as most of your objections are dealt with there.
"Look, all I'm asking, is for you to just have the tiniest bit of vision. You know, to just sit back for one minute and look at the big picture. To take a chance on something that just might end up being the most profoundly impactful moment for humanity, for the history... of history."