SETI: What has it ruled out?


by Rasalhague
Tags: ruled, seti
Rasalhague
Rasalhague is offline
#19
Feb7-10, 06:33 AM
P: 1,400
Quote Quote by twofish-quant View Post
One thing that *I* find strange is that science fiction stories about interstellar travel always assume a breakthrough in physics, when I think that what may make interstellar travel possible is a breakthrough in biology that stops aging. Now what a human society of people that are practically immortal would look like, that's an interesting question, and I'm surprised that people haven't written more science fiction stories about this.
I wonder if this is because we're so used to steeling ourselves to the apparent inevitability of death that we almost daren't imagine that it could be otherwise. If that makes any sense... Like not wanting to let our guard down. Then again, throughout history people have entertained beliefs about the possibility of living forever, so I'm sure we could get used to it.

Quote Quote by twofish-quant View Post
One question that I think would be interesting is suppose I could live for tens of thousands of years. I'm not sure that I'd want to, which gets into interesting questions.
I heard about a TV programme on which an advocate of life-extension asked the audience who wants to live forever. Not many hands raised. Then he asked: who wants to die now. No takers...

Quote Quote by twofish-quant View Post
In human society, suicide and murder are considered horrible crimes because human life is so brief and precious. Suppose we were to meet aliens that never aged. Would *they* consider murder to be something even worse they we do, or would they not care about it?
Perhaps life would be considered more precious if we had more of it to lose, or after we'd had hundreds of years to get used to it in. If death wasn't accepted as something that was bound to happen sooner or later anyway, maybe it would seem like even more of an affront. As it is, we see it as especially bad if someone dies young "with their whole life ahead of them". Of course, there's the principle that rare things are worth more, but at any time we're faced with the immediate prospect of death, our own lives are rare!
Rasalhague
Rasalhague is offline
#20
Feb7-10, 06:41 AM
P: 1,400
This raises the interesting question of what's universal in morality and what's parochial. For a hopeful view, try "Steven Pinker: A brief history of violence".

http://www.youtube.com/watch?v=ramBFRt1Uzk

He mentions Peter Singer's idea of an "expanding circle" of fellow-feeling. I recently heard a similar expression attributed to Albert Einstein. If rational beings tend to evolve culturally towards a kinder ideal, we might be in luck. And the harder it is to travel between the stars, the more time it gives for cultures to grow out of their more vicious aspects.
Rasalhague
Rasalhague is offline
#21
Feb7-10, 06:54 AM
P: 1,400
Quote Quote by twofish-quant View Post
But would space aliens have anything resembling the same sort of "economics" than we have? One thing that we do see in human societies is that people often take major journeys for non-economic reasons. There are people that go around to every village that they can find so that they can spread the word of God.
Good points. I wonder, if two technological species evolved independently to equal levels of complexity, whether they'd become more comprehensible to each other the more complex they got (supposing there are universals in thought that would be more easily recognised then), or less so (as they diverge from the predictable universalities of a basic struggle for survival).
ideasrule
ideasrule is offline
#22
Feb7-10, 09:41 AM
HW Helper
ideasrule's Avatar
P: 2,324
Quote Quote by Rasalhague View Post
He mentions Peter Singer's idea of an "expanding circle" of fellow-feeling. I recently heard a similar expression attributed to Albert Einstein. If rational beings tend to evolve culturally towards a kinder ideal, we might be in luck. And the harder it is to travel between the stars, the more time it gives for cultures to grow out of their more vicious aspects.
It might as well be that dictatorial countries are more likely to push the limits and spend enormous money on space travel for purposes of national pride or personal glory.
Count Iblis
Count Iblis is offline
#23
Feb7-10, 10:21 AM
P: 2,159
http://arxiv.org/abs/0803.0409


SETI and muon collider
Authors: Z.K. Silagadze
(Submitted on 4 Mar 2008)
Abstract: Intense neutrino beams that accompany muon colliders can be used for interstellar communications. The presence of multi-TeV extraterrestrial muon collider at several light-years distance can be detected after one year run of IceCube type neutrino telescopes, if the neutrino beam is directed towards the Earth. This opens a new avenue in SETI: search for extraterrestrial muon colliders.
twofish-quant
twofish-quant is offline
#24
Feb7-10, 11:30 AM
P: 6,863
I should point out that one reason people should fund SETI is that if we weren't thinking about space aliens, we wouldn't have gotten ourselves into this conversation. SETI is really, really cheap.

Quote Quote by Rasalhague View Post
Then again, throughout history people have entertained beliefs about the possibility of living forever, so I'm sure we could get used to it.
Note here that this isn't living forever, just a very, very long time by current human standards. One thing that is becoming obvious is that our bodies are evolutionarily programmed to self-destruct after a few decades.

One common theme in human society is that people often get exactly what they want, but they haven't thought ahead about what they would do if they got it. Just one example of the changes that could happen if people were able to live indefinitely. Right now even the more powerful politicians grow old and die. What if that wasn't true? Imagine that in 1985 some scientists discovered the secret of aging. What would American politics look like now?
dilletante
dilletante is offline
#25
Feb7-10, 12:30 PM
P: 97
A couple of thoughts -- there are certainly economic barriers to exploring the stars. We can't even afford to go back to the moon. Of course, if a rogue star or some other disaster was heading our way and we determined that life here would be wiped out in 2000 years, economics would be superseded by survival considerations. That would be a good reason to put all of our resources into space exploration. And if we found a habitable planet in another system to move to, too bad for anybody who happened to be living there. Our military would be the first to arrive, no question.

So my guess is that the most likely reason we would be visited is because a civilization is looking for another place to live. Exploration of the galaxy on a large scale would require a huge amount of resources, and a civilization willing to mount such an effort is likely doing so out of necessity rather than curiosity. So while I hope that SETI is successful in identifying intelligent life elsewhere, I am not sure I am anxious to meet them in person.

I don't think that SETI has ruled out much with regard to intelligent life in our galaxy. I doubt that our current technology is capable of picking up signals from very far away unless someone wants to be heard, and if they are smart, they probably don't want to be heard. If we do hear from someone, we will probably make the mistake of replying. If our own planet was in danger, the correct strategy would be to send out signals hoping for a response, so we would know where to go. That is a lot more efficient than sending spaceships in all directions looking for a needle in a haystack. Our signal would convey that we are friendly and wish to share our technology, a Trojan Horse so to speak. Beware of aliens bearing gifts.
Rasalhague
Rasalhague is offline
#26
Feb7-10, 11:40 PM
P: 1,400
Quote Quote by twofish-quant View Post
Note here that this isn't living forever, just a very, very long time by current human standards.
Yes, of course. Imagine how it would change our (admittedly dodgy) perception of risk.

Quote Quote by twofish-quant View Post
One thing that is becoming obvious is that our bodies are evolutionarily programmed to self-destruct after a few decades.
I remember the first time I heard this idea. It's a big change of perspective! That said, I gather unprogramming it will take more than hitting a single "stop killing me!!!" switch. But I don't know much about this.

Quote Quote by twofish-quant View Post
One common theme in human society is that people often get exactly what they want,
(Although that's not our biggest problem, I'd suggest!)

Quote Quote by twofish-quant View Post
but they haven't thought ahead about what they would do if they got it. Just one example of the changes that could happen if people were able to live indefinitely. Right now even the more powerful politicians grow old and die. What if that wasn't true?
Would they be more cautious and kind, reasoning that even if they aren't prosecuted for war crimes this century, the way ethics are going, someone will call them to task eventually, maybe for something that no one yet thinks is wrong? Or would they be so afraid of the inevitable backlash that they try even harder to cling onto power, maybe for a very long time... I guess we might see a bit of both. But our instincts having evolved to deal only with short-term consequences, people's actual strategies for surviving and thriving over vast periods of time might turn out to be even more irrational than their current strategies.

Quote Quote by twofish-quant View Post
Imagine that in 1985 some scientists discovered the secret of aging. What would American politics look like now?
I saw a programme, 90s maybe, in which a researcher/advocate of life extension was asked if he had the exixier of life, who he'd give it to. I think his first choice was Ronald Reagan, followed by Margaret Thatcher.
Flustered
Flustered is offline
#27
Jan24-12, 01:48 PM
P: 75
How would radio signals even reach us in the first place from another galaxy? Seeing as it is red-shifting away from us. Also If the light from the galaxy is just now getting to us, and that light left millions or billions years ago, that would mean if there was life in the last 5 million years, the radio waves wouldn't even reach us until we are all dead.
Drakkith
Drakkith is offline
#28
Jan24-12, 09:02 PM
PF Gold
Drakkith's Avatar
P: 11,057
The red shift would only be high from far away galaxies. Nearby ones are mostly unaffected. And yes, if we received a message from a nearby major galaxy it would have been sent millions of years in the past.
yenchin
yenchin is offline
#29
Jan25-12, 02:30 AM
P: 534
By the way, I find this book "Contact with Alien Civilizations: Our Hopes and Fears about Encountering Extraterrestrials" an interesting read.
spark802
spark802 is offline
#30
Feb14-12, 10:33 AM
P: 40
This is quite an interesting thread. There is a book i have read that has addresses seti a little.

The books main point is that we; The earth itself is probably the only world to get as advanced and complex as can be, as in one of a kind.


Rare earth: why complex life is uncommon in the universe (2000)




Dave
Drakkith
Drakkith is offline
#31
Feb14-12, 04:18 PM
PF Gold
Drakkith's Avatar
P: 11,057
Quote Quote by spark802 View Post
The books main point is that we; The earth itself is probably the only world to get as advanced and complex as can be, as in one of a kind. Dave
I personally don't believe this. The results of the Kepler mission have proven extremely fruitful so far. I can't see Earth being "one of a kind".
mjacobsca
mjacobsca is offline
#32
Feb14-12, 04:26 PM
P: 98
The Kepler mission has proved that planets are extremely common, and rocky planets probably are as well. The Rare Earth theory does not disagree with this. The Rare Earth Theory even says that life is probably common. However, it lists numerous variables that pose enormous challenges to complex life, none of which Kepler has ruled out. I recommend you check out the theory to see some of the other concepts that it covers.
Drakkith
Drakkith is offline
#33
Feb14-12, 04:40 PM
PF Gold
Drakkith's Avatar
P: 11,057
Quote Quote by mjacobsca View Post
The Kepler mission has proved that planets are extremely common, and rocky planets probably are as well. The Rare Earth theory does not disagree with this. The Rare Earth Theory even says that life is probably common. However, it lists numerous variables that pose enormous challenges to complex life, none of which Kepler has ruled out. I recommend you check out the theory to see some of the other concepts that it covers.
I don't disagree with the challenges to life and all that, I simply disagree with Earth being one of a kind. We'll have to wait and see what happens in the future, and I am excited about it!
spark802
spark802 is offline
#34
Feb14-12, 07:31 PM
P: 40
HI Again, i like the fact that u are optimistic Drakkith,

I Want to borrow your quote Drakkith "It's not about what's possible, it's about what's probable"

I've read Brownlee and Wards book a couple of times over and i ask; is there other life out there? Probably.

I then ask; is a twinlike planet for the earth possible? Remember all the criteria that has to be met.

We need a moonlike sattelite to keep us locked in axial tilt. Early life needed tidal pools also our moon is involved. We need a jupiter like planet to act as a attractor to sweep up debris otherwise destined to impact here. We know we can survive some big impact events as long as they are rare. We need interior convection and plate tectonics/ vulcanism. Vulcanism releases gases that help retain warmth and regulate the atmosphere.

We need a strong magnetic field and the properties of ozone. We need the earths mass as it is to keep the atmosphere intact. We need to keep some fresh H2O locked up as ice.

All of this has to happen over a very long period. And luck/happenstance cant hurt.

We need to dodge the odd cosmic bullet....

Are "Earths" possible twice? Or many times over?

I am not a religious person but we could be it.....

Dave
Drakkith
Drakkith is offline
#35
Feb14-12, 07:40 PM
PF Gold
Drakkith's Avatar
P: 11,057
You are assuming a whole lot. There is no guarantee that most of that stuff is required in order for a planet like Earth to form. Or that what caused those things here on Earth are the only things that could cause it. For example, would there be a need for a Jupiter like object to sweep up debris if the amount of debris was much less than our own young solar system? Perhaps several smaller planets would be capable of having a similar effect of clearing debris. Does life really need tidal pools? Does a planet need a strong magnetic field and ozone if it's star puts out less radiation than our own sun?
spark802
spark802 is offline
#36
Feb14-12, 08:08 PM
P: 40
Yes Drakkith you have some good points there.

Dave


Register to reply

Related Discussions
Large class of models ruled out. Beyond the Standard Model 0
Ruled Surfaces Calculus 4
small black holes ruled out by LQG? Beyond the Standard Model 5
UK's Guantanamo ruled illegal Current Events 5
Free Will Deductively Ruled Out? General Discussion 78