Why No Contact Yet ?

noosfractal · 2008-05-09 23:30:34

Can we use that same sort of formula for colonizing to other galaxies?

You can use the same formula, but you run up against a pretty important limit - the age of the universe.

It's that first figure that is the kicker. On average, galaxies are 1 million light-years apart. So travel times alone could easily be on the order of 10 million years. But suppose that 1% of populated galaxies colonize a new galaxy every 10 million years. Then, you'd need 25 billion years (and that's not even counting dark matter galaxies http://en.wikipedia.org/wiki/Dark_galaxy ). But the estimated age of the universe is 14 billion years, so even if some civilization began an intergalactic colonization program soon after the big bang, they'd still only have colonized 1 in a million galaxies. And if life didn't arise anywhere until, say, 8 billion years ago (after supernovas had some time to create the heavier elements) then they'd have colonized only 1000 galaxies.

The distances are truly immense to get to the closest other galaxy for any species from any galaxy.
That might be the ultimate barrier, even with very fast travel and very long lived species the distance will still be daunting.

On those timescales though, who can know? I mean, 100 years ago, it was thought impossible to travel in a vacuum because there'd be nothing to push on.

noosfractal · 2008-05-09 23:35:01

The 1,000 would be an upper bound. One thousand or less.

1000 doesn't seem unreasonable for worlds of origin. But if you've got a million years up your sleeve and tech at the level of star lifting ( http://en.wikipedia.org/wiki/Star_lifting ), I don't see what's stopping you from colonizing the vast majority of stars.

cIclops · 2008-05-10 02:23:47

One of the best SF stories and movies ever explored the idea that there are many ET advanced civilizations, if you haven't seen it, stop reading this and go see them now! The book and the movie are called "Contact" by Carl Sagan.

Gregori · 2008-05-10 04:37:22

there is no contact yet because well, there has been no contact yet.

We don't know if there is other intelligent life out there and we won't really know until we've found it. keep searching!

cIclops · 2008-05-10 04:37:57

We don't even know if there has been contact. The panspermia theory says we are the aliens.

nickname · 2008-05-10 04:54:45

mork_from_seattle,

I agree on that, we really haven't listened to that many places yet for a signal.

We could have a few civilizations trying to contact us right now and just don't have the ears tuned into the right place.

I think the bigger trouble with radio signals though is that they have to be directed at us for us to receive them, or we have to be very lucky in picking something up not really directed at us.

If we receive something it probably means they know about us first before sending.
Them knowing about us before they send isn't a problem, but how would they know we are here before they send, and how would they know we could possibly listen?

noosfractal,

That is interesting that it is possible after colonizing a galaxy to spread to the next one.
The distances are really long to do it and i think you are right it's a time thing for that spread to happen galaxy to galaxy.

I guess with conventional travel even at pretty fast speeds it's a difficult prospect to colonize another galaxy but not impossible.

With unconventional travel it might be a different prospect altogether.
Maybe black hole travel, wormhole, dimensional, time etc.

If unconventional travel is possible we have to wonder about that same question we did before, why are they not here.
Then again we are just 1 galaxy in 250 billion so lots to explore before they happen upon ours.
With that sort of technology when they find us would they even be interested in us?

nickname · 2008-05-10 05:10:42

cIclops,

I think we are aliens, but not in the conventional sense of ET.
Life seems to take a quantum leap on Earth from nothing to very complex, so us being the decedents of alien microbial life is quite possible.

It's difficult for even that sort of life to spread around a galaxy in hibernated format, but not impossible.
The decedents of that life might have gone through many stages on the original life world.
It just spread as more complex life as we see the first life on Earth.

Terraformer · 2008-05-10 06:08:11

Check out the Galactic Habitable Zone.

http://en.wikipedia.org/wiki/Habitable_ … table_zone

It's not a very good description, but it'll have to do. It missed out the fact that life can't arise in the Spiral Arms because of there being too many stars.

The age and size of the galaxy has to be right to allow enough Metals to form. In our local group it leaves only the Milky way and Andromeda. Also, Spiral galaxies offer the best chance for a GHZ because of their shape.

The Sun has a higher than average proportion of Metals in it for stas of a similar age. The planets have to form correctly, if it wasn't for Jup[iter we wouldn't have Earth.

Including all the possible sites, our nearest neighbor will be in Andromeda, probably further away.

nickname · 2008-05-10 06:55:02

Terraformer,

When we exclude the places in our galaxy intelligent life won't be it leaves us very few places it might be.

If things have to be very much like our system in all respects then probably just a handful of places intelligent life could be in our galaxy.

If those places don't naturally start up life or intelligence isn't a normal route for life then we could have no others in our galaxy.

my guess would be 100 million stars as likely candidates in our galaxy.
1 in 100 is somewhat similar to our system.

1 million.

1 in 1000 has Earth/moon sort of system at the right place with all the needed attributes we have in our system.

1,000

1 in 1 develop life. (very optimistic)

1 in 100 have life long term with just the right planetary impacts that alter the development of life without destroying it.

10

1 in 10 develop intelligent life because everything was perfect.

1

Pretty easy to get to 1

mork_from_seattle · 2008-05-10 07:54:32

Another way we can detect life is with the next generation of interferometer telescopes. In 20+ years we'll have NASA's tpf or ESA's darwin and whatever comes after them. These will let them image the light from earth-sized worlds out to 50+ ly and learn about their atmospheric composition. Our own atmosphere is maintained by biology so if we see something similar, that would be interesting.

Eventually (in 100 years +) we could have planet imagers that give us views of the cloud cover, surface features, etc. Without ever leaving home. I believe the SETI@Home guy has pointed this out as a reason why aliens might be sending radio traffic to us, they could have been watching us from the comfort of home for millions of years. Our atmosphere has been "broadcasting" for a long time.

Interferometer stuff:

http://collab.digitaluniverse.net/wiki/ … from_Space
http://planetquest.jpl.nasa.gov/TPF/tpf_index.cfm

nickname · 2008-05-10 11:20:52

mork_from_seattle,

I think looking at another civilization within 100 LY's is probably a better way than listening for the radio signal.

I would think within 100 years we would be able to do just that.

Our radio/TV bubble only endure about 1LY then becomes background noise.
Even very advanced beings wouldn't detect us with our radio/TV signals, they would be to weak to detect from even the next closest star.

If they could see us first then send Radio signals that is a different story.
High powered directed radio signals can easily make it stellar distances as long as they are pointed at something.
I think they would have to be pretty similar to us technically or just a bit more advanced to contact us.

If they are extremely advanced and have been trying to contact us for a million years, they would probably either figure we are dummies or come and see why we didn't send a message back.

I think we would have nowhere near that sort of patience after discovering another intelligent species, maybe 100- 200 years and if they didn't make contact back we would go and say hello in person.

bobunf · 2008-05-10 12:42:01

“Our radio/TV bubble only endure about 1LY then becomes background noise.”

Do you have a source for this assertion? How is it calculated? Based on what detection techniques? Does it take into account the distant early warning radars for ballistic missiles of the United States and the Soviet Union? I doubt it.

In any case, radio is the least likely means for ET to determine that we are here. Analysis of atmospheric gasses is much easier and has a much longer life span:

Oxygen, ozone, nitrous oxide and methane in sufficient qualities for the temperature all could indicate the existence of life. Detecting the spectroscopic signature of chlorophyll would certainly clinch that. And those gases have been around for billions of years.

Signals from agriculture, metal working and coal burning could give ET knowledge of our technology for as much as 10,000 years.

Industrial gasses such as chloroform, gasoline, kerosene, naphthalene, benzene, DDT, methyl cloride, Freon and their by-products would give ET an interesting set of patterns to follow for about two centuries.

Radio comes in dead last.

Bob

mork_from_seattle · 2008-05-10 13:35:04

I think Ive read that carrier signals from tv could be detected quite far out. Heres a link that suggests they could detect them out to 50 ly with a 15 square mile tv antenna array. We may have the square kilometer array built in the next few decades so it's not totally farfetched.

http://www.space.com/searchforlife/0802 … -them.html

There are so many variables:

Did they search for light first and find our atmosphere suitable?
Have they sent and we havent searched the right star?
Have we guessed the proper frequency?
Are they using radio to respond? Or lasers? or something else?
Are they interested in actively signalling us?

I read an article where it was suggested that an ETI civ using data compression to maximize efficiency would cloak any message and make it seem like background radiation. We can already do that. We arent just looking for ET, we are looking for extroverted ETs who want us to find them. I'm much more optimistic about finding simpler life using telescopes than an ETI looking to make a friend.

bobunf · 2008-05-10 14:52:11

Excellet post Mark. Right on.

Bob

nickname · 2008-05-10 17:13:00

bobunf,

I have no direct source as a link for the radio/TV dispersal patterns.
Probably not to difficult to do the math on a widening signal to figure the distance it would be receivable with the araceibo dish at any given distance.

I saw that 1 LY statement on a science show on TV about the radio bubble myth so i assume they had pretty good data on it.

mork_from_seattle,

Oh i agree finding ET will be a difficult task at best, if they are reclusive all the more difficult.

So many possible means of communication probably exist, we might not have even thought of some of the right ones yet.
Even if we are using the right one like you say we might be looking the wrong way.
Lots and lots of reasons we might see a noisy sky as a quiet one.

Same old problem with building a 50km array.
If we built a 1km one and had no success with it at all will we build a 10km, then a 25km then a 50 km one?

We might get to the 10 km size one but if it has no success, then it would be very difficult to build the 25 km and justify it.

We might discover that optical telescopes in space run into that sort of problem if we don't detect an earthlike place pretty quick.
At some size with no luck we will have to justify the next size.

With any technology not returning results and equipment that is expansional expensive as it is sized up, sooner or later its just to expensive to justify.

I think if someone is trying to contact us they will attempt to make it pretty simple as we would if we were trying to contact them.
I doubt they will expect us to build 50km dishes to receive the signal they send.

If they really wanted to contact us i suspect the easiest way would be to send a TV signal directed to Earth, that would get our attention even if it was scrambled and unusual to us.

ET-HBO

noosfractal · 2008-05-11 00:37:07

Here is an article that talks about how far out TV signals may be detectable ...

Aliens Can Watch `I Love Lucy', Lou Scheffer
http://contactincontext.org/cic/v2i1/lucy.htm

Here is a web calculator for other types of signals ...

SETI Range Calculator, Eric Johnston
http://www.satsig.net/seticalc.htm

Note that we think that _very_ large "virtual dishes" can be constructed using VLBI techniques ...

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

nickname · 2008-05-11 05:37:21

noosfractal,

Interesting article on Lucy TV.
Go big or go home i guess is the theme.

The catch 22 i see in building such big equipment to see our TV signals is that to build it in the first place you must know we are here, and to know we are here you must build the equipment first.

I guess if ET discover a different civilization very close to them.
It's possible they put up a decent sized dish for science originally, then detected a very weak signal from them while doing science.
As communications became more prevalent they both put up very large dishes to chat more easily.

Then one lucky day for one of them they hear a very very faint signal from us while doing some checks for others with the big dish equipment they both now have.

This seems the only logical way to get to equipment that has a chance to hear our signals without building it first and just wishing someone exists with radio.

Terraformer · 2008-05-11 06:24:39

How far away is Andromeda? We ren't exactly going to have meaningful conversation with the only other civilisation within 250 million ly.

nickname · 2008-05-11 07:56:01

Terraformer,

I believe the Andromeda galaxy is just over 1 million light years away from us.

Difficult to imagine any technology that can make for a meaningful conversation at those sort of distances.

Even some form of communication a million times the speed of light would take 1 year each way, the method of sending a signal would need to be about a million times more directed than any method we have.

Bet the receiver would be a monster also.

That would be one long distance phone call, the long distance bill would go on for a while, many pages.
The day before they mail that you, you might want to be off planet. LOL

bobunf · 2008-05-11 09:33:52

“The catch 22 i see in building such big equipment to see our TV signals is that to build it in the first place you must know we are here, and to know we are here you must build the equipment first.”

As I keep pointing out ET doesn’t need radio to know we are here. He needs a large telescope; perhaps, a bit larger than we are currently building and which will see first light in about eight years. We’ve been using a 600 million square kilometer antenna 24.7 to broadcast the presence of a technological civilization for millennia.

“Oxygen, ozone, nitrous oxide and methane in sufficient qualities for the temperature all could indicate the existence of life. Detecting the spectroscopic signature of chlorophyll would certainly clinch that. And those gases have been around for billions of years.

Signals from agriculture, metal working and coal burning could give ET knowledge of our technology for as much as 10,000 years.

Industrial gasses such as chloroform, gasoline, kerosene, naphthalene, benzene, DDT, methyl cloride, Freon and their by-products would give ET an interesting set of patterns to follow for about two centuries.”

Bob

bobunf · 2008-05-11 09:50:53

“At some size with no luck we will have to justify the next size.”

Radio telescopes and optical telescopes are not usually built with the primary purpose of finding ETs, but for many other scientific reasons. Hubble is not capable of detecting ETs nor is Gran Telescopio Canarias, but both have produced, and will continue to produce, a huge amount of very good science. Arecibo, the Deep Space Network, RATAN-600 and hundreds of other large radio telescopes were not built, and are not used primarily, for detecting or communicating with ET.

As optical and radio telescope get larger there will be returns in the absence of ET detection--scientific returns of great importance, which have driven, and will continue to drive, further development.