The aliens are silent because they're dead

[Rob Lister]

Astrobiology. How is that a fucking thing? Fledgling planet? Who wrote that and why didn't his editor kick his ass.

[DrMatt]

Space is big

[ed]

Astrobiology. How is that a fucking thing? Fledgling planet? Who wrote that and why didn't his editor kick his ass.

want some cranberry juice?

[hammegk]

Whoosh

[hammegk]

Whoosh

[Anaxagoras]

Well I'm sure a lot of them are dead because even here we've had several mass extinctions in the history of life on earth and it may well be that we've been comparatively lucky in those. The asteroid that killed the dinosaurs could have been bigger after all. Or there could have been some other sort of event that would kill not just 90% of species but all of them (perhaps microbes excepted).

But I lean towards the explanation, two-fold really, that intelligent life is much rarer than life. A planet could be brimming with life but lack anything like us which would produce radio signals. The second part of the two-part explanation is that it may be harder than we think to detect intelligent aliens even if they do exist. I doubt they would be intentionally beaming signals in our direction, trying to alert us to their presence, and if not, it may be very difficult to detect them with current technology.

[Doctor X]

On a planet, at the same time as the Earth, life evolved and developed intelligence, communication, Spray Cheese, et cetera.

This planet is one million light years away.

There is the problem.

It is all relative. . . .

--J.D.

[Anaxagoras]

Exactly. And a million light years is actually rather close on the scale of the universe.

[whitefork]

they're silent because they can't have nice things

[sparks]

Not nice: A force of physics.

[Witness]

Not nice: A force of physics.

And what a force!

http://www.reddykilowatt.org/wp-content ... 50x705.jpg

But I think the aliens just keep silent because they first listened in on our radio & TV programs.

[Doctor X]

http://i170.photobucket.com/albums/u264 ... 7nbnem.jpg

--J.D.

[gnome]

I recall some prominent scientist and cynic mulling over Drake's equation once proposed that each civilization might only broadcast detectable signals for 50 years before succumbing to nuclear war or some other self-inflicted calamity.

Interestingly, I think they turned out to be almost right for a different reason--probably no more than a certain number of years before a civilization would switch to local broadcasts that don't bleed out. So aside from intentional broadcasts intended to be picked up from space, there is a "window" of detectability that further reduces the chance of discovering intelligent life via radio teloscopy. (is that a word?)

I imagine each new intelligent civilization "pinging" that bubble as it emerges, and if it's rare enough all might go unnoticed in a short (less than astronomical) listening timeframe.

[sparks]

No. '38. Television broadcast of the Olympic games. From...Germany.

Further, do your maths again AA. If it were '38, that'd be 78 years one way and a round trip of 156. If they responded today via EM at the speed of light, we won't get it until 2094. :)

[sparks]

It does have to be tv as the '38 broadcast was the only thing with sufficient power (and this assumes they have equivalent reception capabilities to us...) to be received. If their reception capability is way better, then all bets are off.

[gnome]

We can fail to reject the null hypothesis (that we are alone) but before we do anything that resembes "accepting" it, it is perfectly reasonable to note that it intelligent life could exist in non-trivial amounts while still not being detected at all yet.

I don't think that Drake's equation is about agreeing on a final figure, so much as it is about expressing the scale of the variables involved.

[Witness]

So my calculation would be 39 light years etc.

But I figured plain radio (or even just wireless telegraph) would be easier to decode than a TV signal (assuming one picks it up in the first place).

https://planetary.s3.amazonaws.com/asse ... s_f840.jpg

Extent of human radio broadcasts
Humans have been broadcasting radio waves into deep space for about a hundred years now, since the days of Marconi. That, of course, means there is an ever-expanding bubble announcing Humanity's presence to anyone listening in the Milky Way. This bubble is astronomically large (literally), and currently spans approximately 200 light years. But how big is this, really, compared to the size of the Galaxy in which we live (which is, itself, just one of countless billions of galaxies in the observable universe)? To answer that question, Adam Grossman put together this diagram. It's not the black square; it's the little blue dot at the center of that zoomed-in square.

"Space is big", to quote Matt.

[Harte]

A guy on ATS just forced me to do the calculation. A 20 gigawatt signal one light year away would reach us with the undetectable power of around 20X10^-22 watts.

IOW, no way Jose.

Try it yourself: link

Don't forget to:
1) convert light years to meters,
2) square the distance

Harte

[ceptimus]

If there are intelligent aliens, it's reasonable to assume that some of them - maybe half - appeared before us.

Given the age of the galaxy, they likely appeared a long time before us - a few tens of millions of years is nothing compared to the age of the earth - let alone other solar systems.

If just one of those intelligent alien species sent out self-replicating space probes, then even if those probes travel at just a few tens of thousands of miles per hour, they've had time to spread across a sizable chunk of the galaxy.

So we have to assume that either there are no such probes, or that the probes don't want to be discovered by civilisations like ours.

[Witness]

↑ That's the Fermi paradox.

[Anaxagoras]

A guy on ATS just forced me to do the calculation. A 20 gigawatt signal one light year away would reach us with the undetectable power of around 20X10^-22 watts.

IOW, no way Jose.

Try it yourself: link

Don't forget to:
1) convert light years to meters,
2) square the distance

Harte

Plus, wouldn't stuff like the nearby star also mask this signal with lots of electromagnetic noise?

I forget, but isn't SETI looking for aliens that might be intentionally sending us a message? It might be hard to pick up their signals if they aren't pointing them right at us, right? Because, why do that anyway? Yeah, perhaps we've done it once or twice ourselves, but we're weird.

[Anaxagoras]

These are more like huge gaping chasms than gaps. The universe is big, as somebody once observed.

If we are the only ones, well, it sure would be a huge waste of space. :wink:



Also not comparable to god in other ways. We know that life (even semi-intelligent life) evolved here. So it is demonstrably possible in principle. Not so with god.

[Anaxagoras]

Scientists can be silly sometimes, too though.

Take those gold-plated records they sent out with the Voyager probes. Did anyone stop to calculate the odds that anyone would ever find these things floating out there in deep space? You'd probably have a better chance of winning the powerball lottery 10 times in a row with just 10 tickets (number pulled out of my ass, sure, but it's only magical thinking to suppose that those probes will ever be seen by anyone other than us again.)

[Witness]

http://communicating.seti.org/

Sending radio messages over sizable interstellar distances is feasible with present day technology. According to SETI Institute radio astronomer Seth Shostak, who presented at the conference, we are already — by accident — constantly signaling our presence to any extraterrestrial astronomers that might exist in our neighborhood of the galaxy. Some radio signals intended for domestic uses leak into space. The most powerful come from radars used for military purposes, air traffic control, and weather forecasting. Because these radars sweep across broad swaths of the sky, their signals travel out into space in many directions.

With radio telescopes no more sensitive than those astronomers on Earth use today, extraterrestrials out to distances of tens of light years could detect them and figure out that they were artificial. The Arecibo radar telescope in Puerto Rico is designed specifically to send a narrow beam of radio waves into space, usually to bounce them off celestial bodies and learn about their surfaces. For a receiver within its beam, it could be detected hundreds of light-years away.

FM radio and television broadcasts also leak out into space, but they are weaker and couldn’t be detected more than about one tenth of a light year away with present day human technology. This is quite a bit less than the distance to the nearest star. The size and sensitivity of radio telescopes is progressing rapidly. An alien civilization just a few centuries more advanced than us in radio technology could detect even these weak signals over vast distances in the galaxy

http://www.universetoday.com/116467/com ... -darkness/

I also remember vaguely having read that with sufficiently low bitrate we could communicate across the Galaxy, even with today's technology. :?

[Anaxagoras]

An alien civilization just a few centuries more advanced than us in radio technology could detect even these weak signals over vast distances in the galaxy

I think they are making assumptions about future advances in technology. Perhaps reasonable assumptions, but still assumptions.

So anyway, they would not see our TV broadcasts (given current technology), only radar signals probably. And then only as far as "tens" of light-years.


That's why I'm not surprised that SETI hasn't found anything yet, and also why I don't think it is strong evidence that we are alone.

[Anaxagoras]

If we are the only ones, well, it sure would be a huge waste of space. :wink:

An argument that implicitly presupposes an intelligent designer.

Hence my winky. :wink:

[Bruce]

The aliens are silent because they're dead
Science Daily

The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens. But life on other planets would likely be brief and become extinct very quickly, say astrobiologists. In research aiming to understand how life might develop, the scientists realized new life would commonly die out due to runaway heating or cooling on their fledgling planets.

...

One way or the other, we're all alone. :)

If you're going to dream, dream small. Very small. :roll:

[Bruce]

Scientists can be silly sometimes, too though.

Take those gold-plated records they sent out with the Voyager probes. Did anyone stop to calculate the odds that anyone would ever find these things floating out there in deep space? You'd probably have a better chance of winning the powerball lottery 10 times in a row with just 10 tickets (number pulled out of my ass, sure, but it's only magical thinking to suppose that those probes will ever be seen by anyone other than us again.)

The odds are probably much less than the probability that life could exist at all in the universe, and yet here we are. :|

:)

[Doctor X]

There was a cheesy but fun science fiction series which opened with Marconi testing his apparatus. Angry puffed up Italian surrounded by incompetents, but he gets it to work.

And off goes his signal.

In to space . . .

. . .

. . . until it reaches a colony of parasites that decide to follow it.

"Where there is life, there is food!"

--J.D.

[Anaxagoras]

I also remember vaguely having read that with sufficiently low bitrate we could communicate across the Galaxy, even with today's technology. :?

Maybe ELF or VLF frequencies?

These are very long waves which can travel through water (useful for communicating with submarines) and even the earth's crust, but as you say, the longer the wave, the slower the bitrate. You also need a very large antenna.

https://en.wikipedia.org/wiki/Extremely_low_frequency

[Doctor X]

I sometimes wonder if astronomers/astrophysicists cannot accept the implications of their own discipline: that the distances are so vast compared to the speed of information transfer limited by the speed of light the reasonable chance of contacting any life form let alone enter into a communication is negligible.

In fact, if I understand the popularly reported physics correctly, the "edge" of expansion of the universe from the Big Bang has passed the point of light ever reaching us. Take that with an appropriate scoop of sodium chloride since I am going on memory. If I understand it correctly, the universe is accelerating and at the "edge" it is accelerating faster than the speed of light which does not violate relativity since it is space-time rather than something within it and fuck it math is involved and math is hard. The point is there are areas which we not only will never receive information from we never can.

So it is not simply that we are receiving light from a star that is effectively a billion years old--what has happened to the planets around that star in a billion years since? Do they have Spray Cheese?--we will never receive signals from a civilization that developed near the "edge" assuming they even can have civilizations because there is probably a sparks there as well.

In the rain.

That is not a satisfying answer. So we keep looking. All wet.

--J.D.

[Anaxagoras]

I sometimes wonder if astronomers/astrophysicists cannot accept the implications of their own discipline: that the distances are so vast compared to the speed of information transfer limited by the speed of light the reasonable chance of contacting any life form let alone enter into a communication is negligible.

In fact, if I understand the popularly reported physics correctly, the "edge" of expansion of the universe from the Big Bang has passed the point of light ever reaching us. Take that with an appropriate scoop of sodium chloride since I am going on memory. If I understand it correctly, the universe is accelerating and at the "edge" it is accelerating faster than the speed of light which does not violate relativity since it is space-time rather than something within it and fuck it math is involved and math is hard. The point is there are areas which we not only will never receive information from we never can.

So it is not simply that we are receiving light from a star that is effectively a billion years old--what has happened to the planets around that star in a billion years since? Do they have Spray Cheese?--we will never receive signals from a civilization that developed near the "edge" assuming they even can have civilizations because there is probably a sparks there as well.

In the rain.

That is not a satisfying answer. So we keep looking. All wet.

--J.D.

Yes, and of course I too am merely a layman in these matters, but let's not let that prevent us from pontificating.
I don't think it's really known for certain how big the universe actually is. Some estimates put the observable universe at about a radius of 46 billion ly IIRC (and there are some decent youtube videos I could link to if anyone cares).

But even our own galaxy is plenty large enough. It contains 100 billion stars. Something a billion ly away would be far beyond our own galaxy (although not so far compared to the observable universe). I would rather confine the search to stuff that's relatively near to us, in our own spiral arm say, or at least prioritize that.

[Anaxagoras]

It's really not such a stretch to suppose there can be unique phenomena in so vast a universe.
Indeed there should be (you should pardon the expression) billions and billions of unique phenomena.

That one planet where conditions are just right for some particular mineral to produce crystals exactly a certain shape and size.

That one planet where conditions are just right for organic chemicals to agonize over existence.

etc. :)

The anthropic principle?

Yeah, could be. But the universe is so huge that I suspect that if something happens once somewhere, it has or will also happen somewhere else. Not in precisely the same way of course. Of course, could be so far away (in space and/or time) that we will never know about it.

[Harte]

A guy on ATS just forced me to do the calculation. A 20 gigawatt signal one light year away would reach us with the undetectable power of around 20X10^-22 watts.

IOW, no way Jose.

Try it yourself: link

Don't forget to:
1) convert light years to meters,
2) square the distance

Harte

Plus, wouldn't stuff like the nearby star also mask this signal with lots of electromagnetic noise?

Absolutely. But it could be handled by using frequencies that can stand out from the nearby star.

Everyone should stop and think about a signal strength of 20 GW. The highest powered signal we use to my knowledge is with certain high power radars which are directed but have a power density of one to five gigawatts.

I forget, but isn't SETI looking for aliens that might be intentionally sending us a message? It might be hard to pick up their signals if they aren't pointing them right at us, right? Because, why do that anyway? Yeah, perhaps we've done it once or twice ourselves, but we're weird.

I guess they do it because there isn't anything else we can do at the present time and (apparently) we don't want to just sit around wondering and not trying in some way to find out.

Harte

[Harte]

Scientists can be silly sometimes, too though.

Take those gold-plated records they sent out with the Voyager probes. Did anyone stop to calculate the odds that anyone would ever find these things floating out there in deep space? You'd probably have a better chance of winning the powerball lottery 10 times in a row with just 10 tickets (number pulled out of my ass, sure, but it's only magical thinking to suppose that those probes will ever be seen by anyone other than us again.)

They shoulda gone with vinyl then.

Harte

[Witness]

The Case for a Gaian Bottleneck: The Biology of Habitability

Abstract

The prerequisites and ingredients for life seem to be abundantly available in the Universe. However, the Universe does not seem to be teeming with life. The most common explanation for this is a low probability for the emergence of life (an emergence bottleneck), notionally due to the intricacies of the molecular recipe. Here, we present an alternative Gaian bottleneck explanation: If life emerges on a planet, it only rarely evolves quickly enough to regulate greenhouse gases and albedo, thereby maintaining surface temperatures compatible with liquid water and habitability. Such a Gaian bottleneck suggests that (i) extinction is the cosmic default for most life that has ever emerged on the surfaces of wet rocky planets in the Universe and (ii) rocky planets need to be inhabited to remain habitable. In the Gaian bottleneck model, the maintenance of planetary habitability is a property more associated with an unusually rapid evolution of biological regulation of surface volatiles than with the luminosity and distance to the host star.

"Gaian regulation"? :shock: But I found the arguments worth a read: http://online.liebertpub.com/doi/10.1089/ast.2015.1387

[sparks]

"...does not seem to be teeming with life..."

Well, it seems the time has come for some marginally tighter definitions for the fuckwits making that claim.

I mean, damnit! This thing (the Cosmos) very nearly qualifies as infinitely big and infinitely old. Throw into that mix the fact that we are here. Now, go masturbate, throw your jizz on Tink, then take a shit and throw that at a GOP presidential candidate(s) and fucking well figure it out.

It ain't all that difficult.

[Rob Lister]

An alien civilization just a few centuries more advanced than us in radio technology could detect even these weak signals over vast distances in the galaxy

I think they are making assumptions about future advances in technology. Perhaps reasonable assumptions, but still assumptions.

Many of those assumptions are rooted in physics; they are actually mathematical proofs. Example: https://en.wikipedia.org/wiki/Minimum_detectable_signal
And since the universe itself has a noise floor, no matter the receiving technology, past a certain point at any given power level, they can't hear us and we can't hear them.

And THAT is the problem with SETI. But SETI isn't [or wasn't] worthless. They demonstrated that life isn't very, very nearby. That is useful and without looking, you cannot otherwise know.

But there is another way. If you can see the planet you can detect the existence of life--And maybe even intelligent life--by looking a the spectral makeup of the atmosphere. Does it contain oxygen? If yes then life. Does it contain fluorocarbons? If yes then smart life.

[Churchill]

Scientists can be silly sometimes, too though.

Take those gold-plated records they sent out with the Voyager probes. Did anyone stop to calculate the odds that anyone would ever find these things floating out there in deep space? You'd probably have a better chance of winning the powerball lottery 10 times in a row with just 10 tickets (number pulled out of my ass, sure, but it's only magical thinking to suppose that those probes will ever be seen by anyone other than us again.)

So you are admitting the odds are greater than zero. :tater:

A little hope, however remote, is worth the price of admission.

[Rob Lister]

Scientists can be silly sometimes, too though.

Take those gold-plated records they sent out with the Voyager probes. Did anyone stop to calculate the odds that anyone would ever find these things floating out there in deep space? You'd probably have a better chance of winning the powerball lottery 10 times in a row with just 10 tickets (number pulled out of my ass, sure, but it's only magical thinking to suppose that those probes will ever be seen by anyone other than us again.)

And to revive this dead thread, a very related, very silly article on Fox

Aliens could conquer Earth by following 'dangerous' maps NASA 'foolishly' sent into space

Back in the optimistic early days of space exploration, everyone thought it was a great idea to offer aliens a chart telling them how to find Planet Earth.

But now the man who sent four maps into deep space fears this decision could prove to be disastrous.

Frank Drake, an American astronomer and famed alien hunter, worked with Nasa to design maps which were placed inside Pioneer 10 and 11 as well as Voyager 1 and Voyager 2 probes.

All four of these spaceships have now left the solar system and are speeding through deep space.

The plaque placed aboard the Pioneer craft shows a man and a woman alongside a basic map which plots the position of Earth compared to a distant pulsar stars, which are bright and long-lasting so could still direct aliens our way if they are found millions of years from now.

Voyager was fitted with "golden records", which can be played to reveal natural sounds and even images from Earth.

A similar pulsar map is engraved on the front of the records.

Frank Drake now fears it may have been a bad idea to send the maps into space.

http://www.foxnews.com/science/2017/08/ ... space.html

I just don't think Frank Drake is all there. It is such a stupid thing to worry about or even consider. The probes are moving at a tiny, almost insignificant fraction of our radio signals that point right fucking to us. And those won't be heard either.

Tell Frank to put down the mushrooms.