What are the odds for "close contact"?

[jhwegener]

We may not give a quantitative answer, but to me the odds seems low. On the one hand interstellar voyages are to my knowledge possible - and are in fact ongoing (Voyager and Pioneer and some others). On the other hand the duration makes them seem rather irrellevant,, and in addition it seems we do not know were they may end, even if they should exist for millions or billions years.
it may not be beyond imagination that this solar system, or even earth has been "visited" - or permanently "occupied" -by such things. But to find one if they should not have perished may make to find the famous needle in the haystack seems easy. And how much knowledge could we get from perhaps very old remnants? Such events if ever could as well have happened 3 billion years ago as now.

[01101001]

What are the odds for "close contact"?

In the next 24 hours? In the next 10000 years? Ever?

Help us out here.

Or are you suggesting first contact already happened? In that case you'd better define what you think first contact is.

[slang]

50%: It'll happen or it won't.

[HenrikOlsen]

50%: It'll happen or it won't.

What are the odd of rolling 1 with a die fifteen times in a row? 50%: It'll happen or it won't.

[jhwegener]

In the next 24 hours? In the next 10000 years? Ever?

Help us out here.

Or are you suggesting first contact already happened? In that case you'd better define what you think first contact is.

In our lifetimes: close to zero. Not very believable for the rest of human existence. Could probes (most likely unmanned "Voyagers")
have reached our solar system or this planet during its 4, 5 000 million years existence? Perhaps, wwhy not. We may never find out
(there may be nothing left, or even if there were, the chances of finding seems very small.

[danscope]

And if ...... IF... someone sent a probe to Earth in the past.....whatever... it probably burned up in about 4 seconds. FFFttttttt...........
Pretty good chance of THAT.

[scaro]

What are the odd of rolling 1 with a die fifteen times in a row? 50%: It'll happen or it won't.

Actually, if my calculations are correct the odds of rolling a 1 with a die fifteen times in a row is 1 in 470184984576. Just sayin.

[ravens_cry]

I would say the chances are pretty low of us meeting them personally. We will probably discover them by radio and or massive telescope before we meet them face to face, if at all, or visa versa.
I think our best hope of contact is our legacy left by our space program, the defunct landers and rovers, the high orbiting satellites, things that will be preserved by the unchanging vacuum for likely far longer then we ourselves as a species will survive. Even if reduced to rubble by meteorites, their material constituents will say to a technology using life form the went down the path of metal and fire that here was mind. And it will still be anomalous to creatures whose tools are grown rather then forged, evidence of a different way of reaching out to the universe.

[aastrotech]

Actually, if my calculations are correct the odds of rolling a 1 with a die fifteen times in a row is 1 in 470184984576. Just sayin.

And if you roll them once per second it would take 14,909 years. In 4 billion years you could expect it to happen 268,285 times

[Gomar]

Actually, if my calculations are correct the odds of rolling a 1 with a die fifteen times in a row is 1 in 470184984576. Just sayin.

is that 7^15? what are the odds of rolling your lottery numbers in a 5 ball game?

[danscope]

Not really great . No . But...... then...... there is the little village of Tully More and a couple of funny guys on a motor bike. Hmmmm...

[Hungry4info]

To answer the OP question.

The odds are 1:50,726.

[neilzero]

I'll say 90% that some humans have already met ET close up. There are perhaps a billion accounts. True most of them are fiction, wild imagination or fish stories, still out of a billion accounts, can 90% probability be unreasonable that at least one is reality? I have no idea which ones are reality. Neil

[ravens_cry]

I am not so sure about that. I don't want to bring religion into this, but before saying UFOS were aliens became all the rage, before the acronym even existed, people liked attributing similar sightings to angels and demons, fairies and spectres.
Should the many sightings be construed as evidence of such? Don't get me wrong, I would love UFO, at least one, to be an alien. But so far the evidence suggests otherwise.

[scaro]

is that 7^15? what are the odds of rolling your lottery numbers in a 5 ball game?

No, it's 1/6^15, cause a die has 6 sides. How many numbers are there to choose from for this lottery? Just 5?

[danscope]

Imagination does not reset the facts. You won't live long enough to get here from there. When you examine the concept of interstellar
travel , we keep running into this severe problem . Hmmm.....

[ravens_cry]

Imagination does not reset the facts. You won't live long enough to get here from there. When you examine the concept of interstellar
travel , we keep running into this severe problem . Hmmm.....

. Imagine an intelligent species with a natural hibernation instinct or have discovered a means of doing so. As long as you don't mind the cultural disconnect, and a religious group may actually want just that, sleeping the way between the stars could be a viable means of interstellar journey with relative ease.

[R.A.F.]

I'll say 90% that some humans have already met ET close up.

Yes, but what are you basing that percentage on...credible evidence, or wishful thinking?

[danscope]

Whether you are awake or asleep, no body lives for 5000 years. It's a problem.

[HenrikOlsen]

I'll say 90% that some humans have already met ET close up. There are perhaps a billion accounts. True most of them are fiction, wild imagination or fish stories, still out of a billion accounts, can 90% probability be unreasonable that at least one is reality? I have no idea which ones are reality. Neil

Covered in detail here.
You've got the probability turned around.

[theNater]

I'll say 90% that some humans have already met ET close up. There are perhaps a billion accounts. True most of them are fiction, wild imagination or fish stories, still out of a billion accounts, can 90% probability be unreasonable that at least one is reality? I have no idea which ones are reality. Neil

Space is very, very big; space travel is very, very hard; and humans are very, very good at making mistakes. I estimate the probability of a billion humans all being in error as higher than the probability that humans have interacted with ETIs.

Whether you are awake or asleep, no body lives for 5000 years. It's a problem.

Three things here.

1)No individual needs to survive the trip. A spaceship designed for it could have occupants giving birth to and raising generations of children.
2)There are individual organisms on earth that are approximately 5000 years old. For example, the Great Basin Bristlecone Pine known as Methuselah.
3)Due to relativistic time-dilation effects, if the spaceship can be made to go fast enough, its occupants can arrange to age only 5 years during the 5000 year trip.

[RalofTyr]

There more of a chance over the next million years humans encounter a forgotten species of human that colonized a world and evolved differently.

Given the long time it took for Intelligent life to emerge here and the rarity of systems that can support an Earth-like planet, I'd say, the only close contact would be with alien ruins at van maanen's star or bacteria waiting to evolve someday on Epilson Eridandi.

Whether you are awake or asleep, no body lives for 5000 years. It's a problem.

Not yet anyways.

[skep155]

There more of a chance over the next million years humans encounter a forgotten species of human that colonized a world and evolved differently.

Given the long time it took for Intelligent life to emerge here and the rarity of systems that can support an Earth-like planet, I'd say, the only close contact would be with alien ruins at van maanen's star or bacteria waiting to evolve someday on Epilson Eridandi.



Not yet anyways.

I've had similar thoughts. If we were to colonise a habitable planet and a civilization ending event took place back on Earth (I.e unexpected large asteroid hit, nuclear war) the two worlds could lose contact for tens of or hundreds of thousands of years.

Either that or through advances in technology we could become sufficiently certain that there's something Earth-like a few hundred light years out for us to attempt long range colonisation. In which case we might not hear from the colonists for a very long time if ever.

[danscope]

You touch on one of the great problems. When you go to the ocean and fly a very expensive kite with your week's allowance on the end of all the string you have, do you deliberately cut the line and watch it fly out to sea? No. You are more inclined to fly that one in the field back home where you can retreive it for another day. So let's burn 70 trillion dollars that we will never see again. Non ? Many will feel the same.

[RalofTyr]

I've had similar thoughts. If we were to colonise a habitable planet and a civilization ending event took place back on Earth (I.e unexpected large asteroid hit, nuclear war) the two worlds could lose contact for tens of or hundreds of thousands of years.

Either that or through advances in technology we could become sufficiently certain that there's something Earth-like a few hundred light years out for us to attempt long range colonisation. In which case we might not hear from the colonists for a very long time if ever.

I don't think we need a nuclear war or asteroid impact; I think the vastness of space would do it. The only reason to travel to another star is to explore or colonize it. There won't be interstellar trade as the distances are too great and each system will be capable of manufacturing anything it needs. Perhaps a low-metal system will require materials from a high-metal system; but likely, these systems would have to be close (10LY) in order to trade (and if a civilization gets to the point in which it uses ALL of the host systems resources, that's one giant system and the laws of carrying capacity should balance it out).

[aastrotech]

There won't be interstellar trade

If you don't include information trade.

[IsaacKuo]

There's also the possibility of energy and/or power trading.

Some star systems, perhaps including star systems like our own, have excessive amounts of energy compared to the amount of matter available. Other star systems, perhaps including brown dwarf systems, have insufficient energy compared to the material available. Long range "eyeglass" configuration lasers and/or relativistic streams can be used to transfer energy from energy rich systems to energy poor systems. The energy poor systems might send matter back in return, although these deliveries would take a very long time to arrive.

Power trading is more subtle than energy trading. There are a number of applications where you don't just want a particular amount of energy--you want it all to be delivered at once in a highly powerful pulse. For example, if you want to collect matter from a planet or a star, one way to do it would be to use a stupendously powerful explosion to blast matter out of its deep gravity well. Using relativistic streams of impactors, it's possible to concentrate the energy of a star's output over several years or decades into a single powerful pulse. You start off with lower velocity impactors and progressively increase the velocity so they all arrive at the target at the same time. However, this only works across interstellar distances--the target must be light years away. So, you can trade such impactor pulses with your interstellar neighbors.

[neilzero]

Human females are not highly reliable baby factories, so you need to launch at least three females, a sperm bank and an embryo bank. At perhaps year 15 the oldest female produces a baby, and at 15 year intervals there after, so in year 61 ages are perhaps 1, 16, 31, 46, 61, 76, 91. We have doubled the population of our generation ship assuming the 91 year old died. We still have 3 that can probably produce a baby. With bad luck we have had some miscarriages, early deaths, and other problems so only one person probably can probably produce a baby, so that person needs to produce a baby ASAP, otherwise an other mishap could result in no more births ever. We certainly do not want to wait 15 years or more to find out if the now 1 year old can produce a baby. The bottom line is we could reach a population of ten with only 3 probably able to produce a baby. Worse, I'm assuming we can avoid the birth of boy babies, which we don't need until we reach our destination, or the sperm bank or embryo bank become unreliable. Euthanizing the worthless eaters would be very bad for moral, and could have horrible morality repercussions. Reasonably the ship has supplies for ten persons for one century, otherwise there will be reasonable apprehension about a shortage of supplies. Most children will grow up as the only child on the ship. That will produce unknown consequences.
Increasing the ship speed from 2% of c to 3% of c may double the possibility of totalling the ship by collision with a small space rock, as maneuvering potential is reduced, the rock can be smaller, and early warning is shortened. Neil

[IsaacKuo]

What is the point of this proposal? Typical generation ship proposals assume large populations, rather than ten or less.

Anyway, you can avoid the birth of boy babies by screening the embryos and sperm for Y chromosomes before storage in the banks. This way, the sex of the babies are known beforehand.

To minimize the chances of multiples, you're going to want to either use IUI or use IVF with just one embryo per attempt--with maybe a 15% chance of success. So, you're looking at a limit of perhaps 1 baby per year per suitable female (maybe 18-40 years old).

Assuming IVF (frozen embryos), the majority of females should be able to successfully produce babies. Assuming a lifespan of perhaps 50 years (due to the severely limited resources of this minimalist ship), that means the majority of the population at any given time will either be fertile or fertile in the future. And even those over 40 could attempt in a pinch--the risk of complications beyond the ship's capabilities is greater, but it's hardly a non-starter.

[neilzero]

So you want to carry supplies for 1000 for a century, that is a very large ship, but it does reduce the probability of no more births ever. Bigger ship means a bigger target for a small space rock. Bigger ship means the children will usually have at least one playmate about the same age and twins or triplets can be compensated for by skipping up to 25 years of births. Skipping 25 years of births means a generation without any children which may produce unknown consequences. Large population also means that at least one person will have the drive and natural born talent to deal with difficult problems which will occur enroute and at the destination. Large population means reduced inbreeding after the sperm bank and embryo bank become unreliable. Is it reasonable to expect that several percent of those born on the ship can learn to do IVF skillfully? We maybe surprised that the average life span is about 100 instead of 50, but that perhaps does not matter if we have accommodations for 1000 people. How can we ensure that the passengers won't be extravagant with the supplies rather than minimalist? Hibernation of perhaps 2/3 of the crew may solve problems, as the useless eaters and non-conformists can be hibernated, if we ever have reliable hibernation for humans. Neil