SETI: Run by charlatans or fools?

[Dinosaur]

From my Post #169:

. . . . .consider the possibility of picking up a sign from a planet orbiting Proxima Centauri, assuming that ET’s there were actually trying to signal the third planet of Sol.

ET is orbiting Centauri & we are orbiting Sol.

Unless the signal was sent in a very precise direction, it would likely miss the Earth.

Even if they had very precise knowledge of our solar system, including the parameters of our orbit, it would be a formidable task to direct a signal precisely enough to hit rather than miss the Earth.

Our receivers are incredibly smaller than the Earth.​

The above assumes an ET circa 4 light years away. At greater distances the problems are even more formidable. I think the next closest star (Bernard’s?) is circa 8 light years away.

BTW: A Poster here suggested a signal propagated as an expanding cone of radiation. The strength of such a signal would obey an inverse square law & would not be strong enough to be picked up by our receivers after traveling 4 or more light years.

Consider signals such as our radio/TV transmissions intended for reception by people on our own planet. There is no reason for them to be powerful enough to be detectable at interstellar distances. Yet that seems to be what the SETI folks are expecting.

In Post #180, ss Watters questioned the validity of the above. To support my POV, my Post #193 provided the following:

1 Degree = pi/180 radians
One second of arc = pi/180*3600 radians
One second of arc = 0.000 004 4814 radians
For small angles (in radians): sin(angle) = angle
Lightspeed: c = 299,792,458 meters per second
Year = 365.242199 days
Year = 365.242199 *24*3600 seconds
LightYear = 365.242199 *24*3600*299,792,458 meters
0.000 004 4814*LightYear = 42 396 424 746 meters.

From the above a directional error 1/3600Degree = 42 396 424.746 kilometers @ 1 light year & 4 times that amount for signals from Proxima Centauri to Earth or vice versa.

That looks like enough of an error to miss an entire planet. It would be even easier to miss the receivers, which are a lot smaller than a planet.

In Post &197, Russ Watters posted the following:

. . . . ."wattage" does not appear anywhere in your calculation. All you did was compare some angles you pulled out of the air as if they had relevance. What is the source for your claim of a directional error of 1/3600th degree being required or existing? . . . .

The above indicates that you have little understanding of mathematics (& perhaps not much relating to physics).

Wattage is irrelevant to a discussion of directional error. Wattage & the sensitivity of the receivers does not matter if the signal misses the receivers. 1/3600 of a degree was an assumed error in direction. Making assumptions for use in a mathematical analysis is common practice. Idoubt that you understood the calculations I provided. Perhpas you understood & knew you could not dispute them.

: Russ mentioned the Aricebo message, which seems like another SETI-like experiment. From Wikipedia:

Because it will take 25,000 years for the message to reach its intended destination (and an additional 25,000 years for any reply), the Arecibo message was more a demonstration of human technological achievement than a real attempt to enter into a conversation with extraterrestrials. In fact, the stars of M13, to which the message was aimed, will no longer be in that location when the message arrives. According to the Cornell News press release of November 12, 1999, the real purpose of the message was not to make contact but to demonstrate the capabilities of newly installed equipment.

Aside from questioning his knowledge of Mathematics & Physics, I wonder if Russ actually reads or understands the citations he provides. Note that the Aricebo folks admitted it was merely a test display of their their equipment rather than an attmept at interstellar communication.

 

[paddoboy]

: Russ mentioned the Aricebo message, which seems like another SETI-like experiment. From Wikipedia:Aside from questioning his knowledge of Mathematics & Physics, I wonder if Russ actually reads or understands the citations he provides. Note that the Aricebo folks admitted it was merely a test display of their their equipment rather than an attmept at interstellar communication.

Any broadcast of any description undertaken by SETI folk is an attempt at interstellar communication.

The title of this thread is no more than an emotional reaction by someone with some sort of axe or agenda to grind.

 

[Russ_Watters]

From my Post #169:In Post #180, ss Watters questioned the validity of the above. To support my POV, my Post #193 provided the following:In Post &197, Russ Watters posted the following:The above indicates that you have little understanding of mathematics (& perhaps not much relating to physics).

Insulting me doesn't make you look any better. You have no idea who I am or what my qualifications are. But you are certainly demonstrating yours. Indeed, dropping any attempt to argue scientifically and resorting to pure hostility is often a sign of recognition that one's position is flawed.

Wattage is irrelevant to a discussion of directional error. Wattage & the sensitivity of the receivers does not matter if the signal misses the receivers.

Agreed, so only a total idiot would send a signal that would miss the intended target. Thus, you have to consider what pointing accuracy and beam diameter you need and can produce. Then you have to see if that gets you what you need in terms of power density. You've professed to try the first part and say it can't be done, but it can. We can produce a signal with nearly any beam diameter we want.

In this case, we have information from SETI about their beam width - there is no need to assume it. So you tell me: Will the Aricebo message hit its target?

1/3600 of a degree was an assumed error in direction. Making assumptions for use in a mathematical analysis is common practice.

Sure. And they always need justification.

Idoubt that you understood the calculations I provided. Perhpas you understood & knew you could not dispute them.

Putting it in bold doesn't make it true. Honestly, lashing out like this I'm not sure you really understand what you are trying to prove - you're just trying to cover your retreat with aggression. The bottom line is: If the beam diameter is 1 arcminute, then 1 arcsecond pointing accuracy isn't required.

You haven't made a relevant calculation: you simply assumed it isn't possible so you decided you don't need to do it. It's nonsense.

So here's a test: using the information I provided, calculate the beam diameter of the Aricebo message.

Note that the Aricebo folks admitted it was merely a test display of their their equipment rather than an attmept at interstellar communication.

I was open about it being just a demonstration: but it was indeed a demonstration that what you claim is impossible is actually possible. Be careful down this road you are on: you are about to inadvertently argue that SETI should set up a permanent beacon.

 

[billvon]

Wattage is irrelevant to a discussion of directional error.

It is quite relevant since antenna gain is proportional to narrowness of beam. If you want a very high gain antenna (transmitter or receiver) it is going to be very directional; if you can live with less gain it can have a wider pattern.

Wattage is irrelevant to a discussion of directional error. Wattage & the sensitivity of the receivers does not matter if the signal misses the receivers.

Again it's quite relevant. Antenna beam patterns have maxima and minima; you will almost never be right at a maxima. Thus you have to figure out how much you are off by, how much the signal has dropped off, and whether the remaining gain, amplifier noise floors and detectors are sufficient to receive a signal.

 

[Dinosaur]

Russ: Provide the data & I will try some calculations.

So here's a test: using the information I provided, calculate the beam diameter of the Aricebo message.

I do not want to take the time to search for it.

BTW: You seem to be the expert on wattage calculations. Perhaps you can do those calculations.

Are you aware that you have accused the Aricebo folks of being idiots.

Agreed, so only a total idiot would send a signal that would miss the intended target.

The Aricebo folks state that their signal was merely a test demonstration of their equipment & that the signal would miss its target.

 

[Russ_Watters]

Russ: Provide the data and I will try some calculations.

[sigh - Why am I having to spoon-feed you this?] In post #180, I quoted this:

The broadcast was particularly powerful because it used Arecibo's megawatt transmitter attached to its 305 meter antenna. The latter concentrates the transmitter energy by beaming it into a very small patch of sky. The emission was equivalent to a 20 trillion watt omnidirectional broadcast...

http://www.seti.org/seti-institute/project/details/early-seti-project-ozma-arecibo-message
You should be able to calculate the width of the beam from the two wattage numbers provided.

BTW: You seem to be the expert on wattage calculations. Perhaps you can do those calculations.

One thing at a time: First you must recognize that the wattage calculations actually matter and that your claimed aiming problem was completely bogus.

Are you aware that you have accused the Aricebo folks of being idiots.

Agreed, so only a total idiot would send a signal that would miss the intended target.

Uh, no, you are the one who started this thread and are continuously accusing them of either being idiots or liars, without thinking-through what they are doing and you are the one who claimed their signal would miss their intended target. Only an idiot assumes scientists are idiots and not being one, I intended that statement to prompt you to find another explanation. Ie: since they are not idiots, they didn't send a signal that would miss their target (or, rather as you claimed, couldn't possibly hit it).

But clearly, you already do think they are idiots, since that is how you read my statement. Not only is that incredibly arrogant of you, it is idiotic for you to assume you are smarter than a bunch of phds.