Seti

[Reivax]

After watching this TED Talk I was wondering how solid people think the argument put forward is? Which is basically:

There is an exponential, technological increase in the SETI
There are likely billions of earth-like planets in our galaxy
Therefore, it is very likely that we will make contact in the next two dozen years

I look forward to hearing your responses!

 

[Itztli]

There are likely billions of earth-like planets in our galaxy

The part that's missing: how many of those planets are close enough that we would be able to pick up a reasonable signal with our state of the art technology ? From what I've heard, it's pretty much impossible to pick up random transmissions from anything more than a few light years away.

 

[LarianLeQuella]

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That said, Seth does tend to extrapolate optimistically when talking about this subject. There are natually many counters and caveats to his point of there being billions of earthlike planets, the advances in SETI technology, and then a reliable estimate of a "contact date".

For instance, the data suggests that there may be a whole slew of earthlike worlds out there, but we honestly don't know. That's it. We just don't know, so anything beyond that is a guess.

As to the technology, we would need to consider how our technology is progressing, as well as any potential sender's technology. For instance, we've only been leaking radio signals for a very short time. And as time passes, ant the way we are leaking radio signals is actually decreasing (narrow bands, optic fiber transmission, etc.). Then three is that nasty inverse square law to deal with. Not sure how Seth really thinks we'll overcome that unless he thinks that other civilizations are sending focused beams of communication out in our direction. Something that we ourselves haven't done that often.

Which brings up the point of comparative intelligence. Just because us humans behave one way, doesn't mean that some other intelligent species will try to develop technology or communicate. Maybe to them, the height of achevement is s deep philisophical understanding acheived through introspection or something. Heck, we can't even figure out if other species on our own planet really are displaying intelligence, conciousness, self awareness, etc without it becoming a great big debate. To attempt to extrapolate to a totally alien species will be difficult at best. Since we only consider oursleves as one datapoint, out ability to extrapolate from that is very limited.

That said, I hope Seth's optimism bears out!

 

[Monketi Ghost]

It's all based on a lot of supposition.

The only thing that gives me hope is the number of stars with planetary systems. The only thing that dashes my hope is the distances involved.

They're out there. But the chance that any alien civilization is in a state where they can send messages at the same time we are is remote. We won't be around very long, and neither will mostly any other civilisation. Distances involved + fortuitous timing = not likely.

 

[Skeptical Greg]

Even if we detected an intelligible signal; what would we do with it? Reply ?

Yesir, they're out there ... Now what ?

SETI vs Protein Folding

 

[sarge]

After watching this TED Talk I was wondering how solid people think the argument put forward is? Which is basically:

There is an exponential, technological increase in the SETI
There are likely billions of earth-like planets in our galaxy
Therefore, it is very likely that we will make contact in the next two dozen years

I look forward to hearing your responses!

The chances of contact are so remote as to make it a near-impossibility.

1. Life developing on another planet in such a fashion that we might be able to communicate with it is billions to one against - easily canceling the advantages billions of planets producing the handful that are in the Goldilocks zone.

2. It is extremely unlikely that our civilizations will overlap sufficently to allow us to each be in the proper stage of development. Given the distances involved, the time it takes to deliver a signal, and the relatively short window of opportunity, balanced against the tiny percentage of planets that contain a sufficiently advanced civilization, the chances of contact approach zero.

It's a fine hope, but it ain't going to happen, ever. It's between 50,000 - 70,000 years at the speed of light just to cross to the other side of our own galaxy. It's another 50-70K years back. Barring the most extrodinary luck, the species Man will not survive long enough to stumble upon another species capable of interstellar communications.

Sometimes, an analogy helps with perspective. Try this one - it clicked for me when I first read it:

There are about 1 million grains of salt in a typical salt box (the round Morton type). If you wished to use that box of salt to build a replica of a portion of our Galaxy, using the grains of salt as stars, you'd have to spread the individual grains about 1 mile apart to accurately reflect the scale of distances between individual stars in our galaxy.

 

[Bill Thompson 75]

After watching this TED Talk I was wondering how solid people think the argument put forward is? Which is basically:

There is an exponential, technological increase in the SETI
There are likely billions of earth-like planets in our galaxy
Therefore, it is very likely that we will make contact in the next two dozen years

I look forward to hearing your responses!

If contact means an awareness of life forms in other planetary systems then that may be possible, but not by SETI.
That will take very large telescope array systems that can view planetary surfaces many light-years away. That capability is many years away, if it happens at all, because it depends upon a continuing interest in funding those systems through all economic ups and downs.

If contact means two way communication then that will never happen.

If contact means an awareness that another intelligent civilization has existed at sometime in the past history of our galaxy, then that's not likely to happen either.
This depends upon:
1) another civilization reaching a technological level at least equivalent to ours
2) that civilization surviving all manner of global calamities to broadcast signals for an extended period of time
3) that civilization broadcasting signals within a time-frame that sets those signals to pass by the Earth during our civilization's time-frame.

 

[godless dave]

After watching this TED Talk I was wondering how solid people think the argument put forward is? Which is basically:

There is an exponential, technological increase in the SETI
There are likely billions of earth-like planets in our galaxy
Therefore, it is very likely that we will make contact in the next two dozen years

I look forward to hearing your responses!

Does not follow, for a couple reasons.

We don't yet know that there are billions of earth-like planets in our galaxy. It's certainly possible, maybe even likely, but since we can't even detect earth-size planets yet, we really can't say for sure.

Even if there are, and even if some of them have life on them, and even if some of them have or had intelligent life on them, and even if those life forms built radio transmitters, they might have done it so long ago that the signals already passed us by, and those life forms may well no longer exist or have abandoned broadcast radio as a form of communication.

Or they might exist right now, on the other side of the galaxy, meaning their transmissions, if any, won't get here for another 80,000 years.

Or they don't use radio at all and never have.

Or there just isn't any other intelligent life in our galaxy.

 

[Cuddles]

If contact means two way communication then that will never happen.

That was the point I was going to make. SETI has a chance of finding out that there is, or at least was at some point in the past, other intelligent life. It doesn't give us any realistic chance of actually communicating with it.

Even if there are, and even if some of them have life on them, and even if some of them have or had intelligent life on them, and even if those life forms built radio transmitters, they might have done it so long ago that the signals already passed us by, and those life forms may well no longer exist or have abandoned broadcast radio as a form of communication.

Or they might exist right now, on the other side of the galaxy, meaning their transmissions, if any, won't get here for another 80,000 years.

To be fair, this argument doesn't really work. The question "Is there intelligent life transmitting radio signals towards us right now?" is functionally equivalent to "Are there alien radio signals arriving at the Earth right now?". The probabilities are exactly the same, the only difference is that the second one is the only one we're actually capable of answering. Pointing that out, while entirely correct, doesn't really add anything to the debate since it doesn't have any bearing on whether SETI might find something.

There are likely billions of earth-like planets in our galaxy
Therefore, it is very likely that we will make contact in the next two dozen years

See the Drake equation.

The Drake equation states that:

N = R*f_p *n_e*f_l*f_if_c*L

where:

N = the number of civilizations in our galaxy with which communication might be possible;

and

R = the average rate of star formation per year in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of the above that actually go on to develop life at some point
fi = the fraction of the above that actually go on to develop intelligent life
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space

OK, so lets assume the talk is correct and there are indeed billions of Earth-like planets. That covers the first three terms. That still leaves four terms which are completely unknown. Not just unknown in the sense that we don't have a solid answer yet, but unknown in the sense that we don't even have any data to try extrapolating from yet. So even if you assume we're far more sure of the first terms than we actually are, any final answer is still nothing more than a wild guess. Not just a shaky estimate based on reasonable assumption, simply a completely made up number pulled directly from the wrong orifice. There galaxy could be absolutely chock full of Earths covered in various kinds of life, but fi could still be so low that we'd almost certainly be the only intelligence to ever develop in the whole observable universe.

The Drake equation doesn't give us an answer to how many aliens are in shouting distance, it gives us a list of things we need to know before we can even begin to work out such an answer. And of course, several of the parameters require us to actually have found intelligent life, so by the time we're capable of coming up with even an approximate answer to the Drake equation, there won't be any point in actually doing so.

 

[Itztli]

OK, so lets assume the talk is correct and there are indeed billions of Earth-like planets. That covers the first three terms.

Except when you apply the Drake equation to the SETI program, you need an additional term: how many stars are close enough that we can pick up their transmissions.

Here's a useful graph: http://history.nasa.gov/CP-2156/p404.htm, although it may be a bit dated. On the X-axis, it shows the sensitivity of our receiver, and the diagonal lines are transmitted powers. It says that for a transmitted power of 8 MW (UHF TV), and a receiver sensitivity of 10^-27 W/m², there are 0 planets within range, which puts a huge damper on the whole Drake equation.

Now, we can hope for an alien civilization that uses something like an Arecibo-size dish to aim a powerful signal right in our direction, which would put million of stars within our range, except that it requires that they aim the signal right at us, at just the same time that we are listening in that direction.

As I said, this graph is dated, so maybe we have better technology now, but I'm not expecting miracles.

 

[rcfieldz]

To THEM...

We are probably a rerun of many other lower class intelligent beings.

 

[LarianLeQuella]

We are rcfields is probably a rerun of many other lower class intelligent beings.

FIFY

The rest of us are actually individuals that were born and will die in a distinct timeline. The only part that is recuvled are the basic atoms that make us. Our conciousness is our own.

 

[Halfcentaur]

All this talk of how terrible and arrogant a species we are with such an inflated sense of our accomplishments is making me feel like I'm hanging out with a world of black draped teenagers.

 

[Dancing David]

This is the planet Algon, fifth world in the system of Aldebaran, the Red Giant in the constellation of Sagittarius. Here an ordinary cup of drinking chocolate costs four million pounds, an immersion heater for the hot-water tank costs over six billion pounds, and a pair of split-crotch panties would be almost unobtainable.

Monty Python

Prices on the Planet Algon

 

[Cuddles]

Except when you apply the Drake equation to the SETI program, you need an additional term: how many stars are close enough that we can pick up their transmissions.

That could be covered by fc, with the assumption that by "detectable signals" it actually means "signals detectable by us". On the other hand, people have proposed an absolute ton of modifications to the Drake equation over the years. Personally, I don't think it's all that important exactly what factors you include. After all, an equation that consists entirely of 7 unknowns isn't going to give you a less accurate answer than one that consists entirely of 10 unknowns. As long as it gives a reasonable idea of what we'd need to know to get an answer, the exact details and what you call all the variables aren't so important.

 

[Itztli]

That could be covered by fc, with the assumption that by "detectable signals" it actually means "signals detectable by us".

I would rather make a separate term, especially because we may be able to come up with a reasonable estimate for it, for instance based on the graph I showed. Now if this factor ends up being fairly small, it basically means the answer to the Drake equation is zero, even with only rough estimates of the other variables.

 

[quarky]

This reminds me of an analysis I heard regarding a dating website service in Boston.
Even with a million people in the area, after a very few refining questions in the search, it was quite likely that there was no one for you in Boston.

It was interesting, non-intuitive math, and its least passionate.
With each condition, it was easy to see the million people being reduced to zero.


Perhaps if we dropped the intelligent part of the search?