What would be your vision of a better humanity?

Billy

I think I am going to ask you to either supply some documentation or else admit you are engaging in pure speculation. I am not even sure if prion diseases occur in plants at all.

If so, then what evidence is there that transmission can be airborne. The only case I am aware of, of prion diseases in animals being airborne, is a very artificial one, in which researchers mashed up mouse brains infected with prions, and squirted finely mashed brain tissue into the air so that other mice inhaled it. As I am sure you will realise, this does not happen naturally!

So do you have documentation. If not, we will not take your speculations very seriously.

 

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I don't have any documentation and don't know of any plant prion diseases but in post 65 you essentially asked Killjoy to speculate on what could exterminate man. He did not so I suggested two possibilities - of course they are only speculations - neither has exterminated man, so we don't know if either can.

I will speculate further as to why a plant prion may not have naturally occurred but several for animals have. I think that there are many more natural molecular structures in animals than plants but am not sure of this. Thus there may be a more limited set of molecules found in plants that can fold in several ways, some of which are non-functional for their host /owner but are "foldable" to become prions. I would expect however that at least a few do exist and that 200 years from now a clever, deranged bioengineer could make a prion to exploit one. - I.e. a non-natural, non-chance production of a plant prion does not seem impossible.

As I pointed out, especially in post 78, the delivery of it by air to the insides of a plant organism is much less complex than the ingestion route used by those that have developed by chance / evolved. My main point was that if you want to exterminate man, trying with virus or even bacteria is not likely to kill 100% of humans due to the human diversity in immune systems and other defense systems that have co-evolved with virus and bacteria so that they never can kill all humans. IMHO a better chance of killing ALL comes from making the oceans boil, removing the oxygen from the air* or destroying photo synthesis / the food supply. I could not think of any conceivable way to remove all the oxygen so suggested the other two only.

I am quite willing to drop the discussion of what obviously must be only speculation about means to annihilate man. I expect it will happen, probably in 10,000 year or less I would guess and by means no one did speculate about before it was too late. The human level of intelligence and capacity to change the environment probably is excessive for long term (~100,000years) stability – it only takes one big mistake.
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* Perhaps a large volcano belching hot sulpher for a year or more would use up part of the O2 and more importantly make the air lethal with SO2.

PS I think all prions are in some broad sense man-made and very recently evolved - I.e. I suspect none existed 5000 years ago before large herd of non-grass eating cattle and sheep did. I.e. man provided them the opportunity to be / evolve/ by feed lots and animal derived protein supplements. - Perhaps and early example, not yet 100% fatal, of man being too "smart" for his long term existence.

 

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Billy

All I needed was an admission that this was speculation. Thank you.

Something to destroy all humankind would need to be pretty damn drastic. Major disasters have happened in the past. The extinction event at the end of the Permian era, which 'coincided' with the Siberian Plate vulcanism event, killed 96% of all marine genera.
http://en.wikipedia.org/wiki/Permian–Triassic_extinction_event

It would take something of this magnitude, and that has occurred only once in 500 million years.

 

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I thought it was obviously speculation - all discussion of all things that have never happened in the history of Earth are speculations. For example SETI calculations are speculations as we have never heard from ET and have no solid evidence ET is the origin of life on earth as some speculate, etc.

People who speculate about very adverse events that have never happened can draw some comfort from the fact that they have never happened PROVIDED that the condition that existed previously on Earth still continue, but should those conditions drastically change, then there is no validity to the argument "Well it has never happed in 500 million years."

For example if alien green gue life form falls on every square meter of earth and the breath it exhales is toxic as are the vapors it gives off when man applies flames to it, then it is possible that will be the end of man. That particular "drastict change" has not happened so I don't worry /concern myself with it; however a drastic change has happened:

Man now has the capacity to change the earth and is doing so with greatest RATE of extinctions and atmospheric and oceanic chemistry changes ever.
The cover of current issue of The economist is:

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This text adjoins smaller internal version: "Welcome to the Anthropocene. Humans have changed the way the world works.
Now they have to change the way they think about it, too" - http://www.economist.com/printedition/

I might add, and think it more important, that man has already started to change man. Not yet actively modifying his DNA, except in a few cases, but more so by medically interfering ("for the best of human reasons") to allow those who would die early with genetic defects to live and pass them on to next generations is how man is now modifying mankind. - But you aint seen nothing yet. In a few decades more if you want a tall, blue eye, male, child, just pay the fee and it is yours. We don't have the wisdom to keep up with our knowledge, imho. We have for more several decades made mice with human genes so they get human diseases we can test cures on - man will be modified too. Perhaps in 250 years, with fish DNA added to some "men," there will be underwater cities without need of aqua lungs. The world's population may require cities on the continental shelf then, especially if global warming has brought the oceans far into what is now dry land.

This new drastic event - man's capacity to modify the Earth and the way "nature" functions* - I suspect will be a great disaster in 10,000 years or less. I.e. man is now too "smart" for his long term (~100,000 years) survival, I speculate. As the The economist notes: Earth has entered into a new era, the "Anthropocene."

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* For example with huge RATE of CO2 release, the oceans are becoming more acidic and the coral is dying so the habitat of many small fish is disappearing, not to mention the over fishing of the oceans. Can you, or any one, tell me what the final results of this man-made change of the oceans will be? I speculate that the Japanese, Norwegians (and others who now eat a lot of ocean fishs and whales, which are not fish) will eat more beef, so the cattle herds will be greater, with more forest cut down, and more CO2 produced. - A tiny part of the positive feedback system producing more global warming, and no iron clad guarantee that the end result is not the tropical ocean surfaces boiling for a completely sterile Earth. (Post 71 at: http://www.sciforums.com/showpost.php?p=2761195&postcount=71 explains a mechanism telling how boiling ocean surface is conceivably possible, but very unlikely, I THINK, but I am not sure, nor is anyone else.)

In Brazil, cattle belches are the largest source of Brazil's CO2 release but clearing forests will be a large one time release. The world is so inter connected now it is very hard to know IN ADVANCE, the final result of what initially may seem to be an insignificant change man is making to nature.

 

Nah.

No beef cattle. Instead, we will have a GM steak plant. Just pick a leaf and sizzle it. (Just kidding).

On wisdom.
Our species name, Homo sapiens, literally means 'wise man'.
In spite of all the cynicism expressed here and elsewhere, I believe this is appropriate. True that 95% of the human species are far from wise. But human progress is driven by the very smartest - not by the run of the mill ordinary types like you and me. In terms of progress, we are just support people, to enable the one in a million smartest to drive forward real progress.

As I have pointed out, repeatedly, compared to even 400 years ago, the world today is massively improved as a home for humans. In another 400, it will be unrecognisable, with human life being a heaven compared to today.

And in spite of the pessimism generated by Billy, there is no evidence of any disaster to wipe out humanity in 10,000 years. My feeling is that, by then, humanity will be virtually impossible to wipe out, since we will have self supporting colonies around 100 new star systems. In a million years, our descendents (no longer Homo sapiens, perhaps Homo superior?) will occupy the entire galaxy.

 

Humanity doesn't have to get wiped out, but there are a lot of things that could crash the population and send us back to the dark ages. That list is to long to detail here. Each time we have to start over we will have less resources to work with and less of a chance of getting off world to populate other planets. Yes it is possible that won't happen, but I sure would like to see some better planning to head off all the identified possibilities. Hell we don't do regular disasters very well.

 

You didn't think we would call ourselves: "evolution's mistake" did you? It remains to be seen which is the more accurate designation.

If man does ever get to make civilization on distant planets it will probable be a very improved / changed life form pre-adapted to the natural conditions of those planets. For example if gravity there is 3 times greater, at least much smaller bodies masses with bigger bones and feet. (Perhaps modified pelvis with four legs?)

As far as making a self-sufficient civilization on Mars that may be possible without just sending machines that can construct AM (Adapted Man) from information stored in their computers. I.e. only living carefully-selected females will be sent to Mars to make a human civilization there. For at least 100 generations or so all the sperm they need to become pregnant will come from liquid nitrogen storage tank. When that is gone, they should be advanced enough to make artificial sperm from another woman's DNA to keep the diversity that sexual reproduction gives. Men would double the cost of everything and are not needed.

The Marian Space port will probable have sign that states: "Welcome to lesbian land"

 

Killjoy

That always remains a possibility, though it is low probability. I tend to believe that it will not happen. This belief is based on the recent record, with such things as ozone depletion, pesticide over-use, Y2K, over-population and other projected disasters being met by humanity, and either the problem overcome, or clearly on the way to being overcome.

As insurance though, as Stephen Hawking pointed out, we need to get a self sustaining colony off planet. The first such will be within our solar system - perhaps Mars - and we should be able to do this within a few hundred years. The first such colony around another star will take 1000 years plus.

That is how long we have to avoid disasters of catastrophic proportions. The odd war, famine, earthquake, or pandemic should only be setbacks. It would take something of truly Earth shattering proportions to achieve what killjoy raises fears about.

 

Evolutions mistakes tend to not survive to long, but unlike humans they also don't take out a large percentage of earths other life forms as they fade from the scene.

That's a big if and the only place we will ever find a livable planet with 3X earth gravity is a long way away and I wouldn't bet the farm on us ever getting there.

I can't believe that's an idea that going to go over very well.

 

I agree with all this except quite often "evolutions mistakes" don't die out, they change / adapt. For example, there are now many more birds species than there were dinosaurs, but birds are adapted dinosaurs.

My main point is now in the Anthropocene era, change comes many thousands of times more rapidly than in the past and we can not know what the final result of this rapid change will be. Natural evolution is much too slow to keep up with this RATE of change. For example dinosaurs would have died out, not become birds, if they had to make that change in only 1/100,000 of the time they did.

 

Maybe, but a Yellowstone eruption is overdue and that would be a big set back for the world and especially bad news to the U.S. population. Melting ice and rising ocean levels could become a serious world problem by 2200 or maybe a little sooner. Over fishing and polluting the oceans looks very bad for the world. Running out of oil will be a serious distraction to accomplishing other good deeds. Also, there's the old standby asteroid or comet coming out of the blue and nailing us.

Some of those things we might be able to mitigate if we can get a little world cooperation, but that's a stretch.

 

All life forms are successful to a point, some more so than others. Some might say dinosaurs were successful because they were around for 50,000,000 years. I say big deal, they started out as dumb animals and they went out that way. Humans may not be around that long, but we actually have a chance to spread to other worlds and if we do, we could actually be around longer than 50,000,000 years, and there's no telling how evolution would treat each group of humans on their new worlds.

 

I suggested (in post 87) that machines would need to make Adapted Man from information stored in their computers, not humans sent in some form of suspended life, as there are only 8 stars you can reach in less than 10,000 years even if traveling at the speed of light - see list at: http://en.wikipedia.org/wiki/List_of_nearest_stars As far as we know, none of the eight has any planets.

However, in honesty, I must admit that 10,000 years would be less time passed to the passengers, but to make that a significant factor requires a great deal of energy for the TWO acceleration periods.

 

Billy

I cannot let you get away with that. Your reference has 49 stars within less than 17 light years. The entire galaxy is within 70,000 light years. This means that travelling at light speed would give access to one seventh of the galaxy in 10,000 years. Or about 15 billion stars.

In fact, the maximum speed a star ship is ever likely to reach, barring some magical breakthrough in physics, is about 0.2c - 20% of light speed. Even at that speed, humanity could reach any one of those 49 stars within less than 100 years travel.

 

Sorry, I missed the decimal point. Yes but the closest one known to have a planet is nearly 15 light years years away or at your more reasonable 0.2C speed the only the second generation could reach it without suspended animation technology (and people willing to let that be done to them)

That planet is not suitable for even four legged adapted man as gravity is nearly 12 times greater than on earth. It orbits its red dwarf sun in less than five days very close to it, which may compensate for the fact the sun is less than half as large as our sun and only 3600K hot. I may do some simple calculations to estimate the surface temperature of that planet. ok calculations done:


This link tells the planet is about 0.038AU from the star http://en.wikipedia.org/wiki/Gliese_674 so that factor alone means each sq. meter of it intercepts (1/0.038)^2 or 692 times more of the stars radiation than Earth does. However the T to the forth law means that total energy being radiated is only (36/58)^4 per unit sun area. Or 0.148 as large and the sun area radiating is only 0.42^2 as large so heat radiation flux from planet's sun in is only 0.026 as great as the earth’s sun.

Summary, the thermal energy (and that is what it would mainly be with a temperature of only 3600K) on each sq meter of the planet is 0.026x692 = 17.99 or 18 times greater than on Earth.

Thus, humans would be well cooked there in less than an hour and well as flatten by the 12 times higher gravity. It is not easy to find a suitable planet, especially one with an oxygen atmosphere as that is very rare since only made by green plants AFAWK.

 

To Billy

We actually do not know what planets the nearest stars may or may not have, because our techniques for observing extra-solar planets still are not sensitive enough to detect small or Earth size planets.

Based on the numbers of planets where they can be detected, it appears that most stellar systems have planets. In addition, it is rather probable that stars will prove to have a lot of debris, such as comets, asteroids etc in orbit. I am basing this statement on the fact that, in our solar system, the number of planets is outnumbered hundreds (if not thousands) to one, by that kind of debris.

My own feeling is that colonies around other stars do not, in fact, have to live on planets. The first star ships will probably be extremely large space habitats, even space cities, that are largely self sufficient. They will spin for gravity, and have effective shielding for radiation. When such a starship gets to another stellar system, there will be no hurry to colonise anything. They will need to replenish some supplies, such as water, and this will be available from space debris.

In fact, they could build any number of space cities in orbit around another star, while never landing on a planet. In terms of mobility, staying in space has lots of benefits.

 

Why go to another star, with all the energy that would take, just to leave our sun from 1 AU distance? Have you made any guestimate as to the energy required for your large colony space ship to leave our solar system? I bet it is more than the energy stored in all the Earth's coal. If true, or even close to true, you would kill everyone left on earth, with the CO2 alone. - I don't think they will finance this project.

Unless you invent some new "no-mass expelled" and very powerful rocket, I think the mass you would need to throw out is about 1% of the earth's mass - just a quick guess. Note it does not make any difference if you use 10,000 earth launches to the moon and build your large colony ship there. You still need to move its mass from 1 AU to non-solar gravity space.

Where does the mass / material come from? And the energy needed to collect it from there and to process it in to metals etc.? For answer to first part, I assume you are thinking of little "space tug ships" that go after "space debris" and bring their mass into same orbit of the colony ship, but unless very lucky with the debris original orbit that probably is a "mass negative" task. I.e. space tug's rocket round trip rocket exhaust mass is greater than the mass it can return to the colony ship.

 

Billy

Your thinking is very 20th Century.

There is going to be no travel to another stellar system for hundreds of years - possible 1,000 or more. By then, things will be very different.

My best guess for the propulsion system is probably (I am guessing no major breakthroughs) a combination of light sail, and an advanced ion drive engine. The light sail needs no reaction mass, and the ion drive engine expels its reaction mass at close to light speed. This high expulsion speed reduces the mass required.

If we had a space city massing, say 10 million tonnes, we would need perhaps 20 million tonnes of reaction mass. The materials to build the city, and the reaction mass (probably ice) can easily be gathered in space. The rings of Saturn alone have 10 trillion times that amount.

My best guess, limited by knowledge of today's physics, of energy source, would be a nuclear fusion power plant.

Why would they go?
Again, I am guessing. However, I would envisage a time, perhaps 1,000 years hence, when there are a number of space habitats/space cities in the solar system, perhaps living by mining space debris. With a space city already set up for near self sufficiency, to go that extra step to interstellar travel is not so difficult. The reason to do it? Perhaps political. Religious. Following a charismatic leader? Wanting to be leaders, not followers.

Oh, and one last point.
By that time, it would not be a blind leap. We can expect technology to be sufficiently advanced that we would be able to 'see' and measure the planetary systems around all the nearer stars. Robot probes would probably already have got there and reported back. And a self sufficient space city would contain peoples who are perfectly willing to live off the gleanings of space debris, indefinitely.

 

in part yes, but you will not change physical laws. For example doubling the specific impulse / exhaust velocity with ion rocket compared to best chemical rocket will require four times the energy to double the thrust as KE = 0.5 mV^2 but thrust goes only as mV. You can reduce the mass by factor of two and have the same thrust and in principle need only the same energy, but ion rocket are much less energy efficient. Mainly as you can not throw out ions but must neutralized them to avoid making net charge on the rocket and an ion attracting electric field which turns the ions around and makes them fall back on the rocket for zero net thrust.

For more than 100 years the the "ideal rocket equation" been known. Here is graphical result for rocket with chemical thrust:

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and that 35 times exhaust mass will get you 3.5 times the exhaust gas speed but that is less than the escape velocity to leave the sun from 1 AU. It is much worse than this curve indicates as it assumes you are far from the sun's gravity and just changing your velocity in deep space.

Instead of your factor of 2, I suspect a mass ratio factor of >300 is more what is needed. Also solar sail will not do anything to keep your colony ship from falling back into solar orbit unless they are very large compared to the diameter of Jupiter. Radiation pressure / sq meter is very small out where Jupiter is. - Have you noticed Jupiter is not being pushed away from the sun by the radiation pressure on it?

I won't go thur careful analysis but you are not even going to be able to take a large 10 million ton ship away form the solar system in century 30, 1000 years from now. It is simply too much energy required to climb out of the sun's deep gravitational well - and worse if your trying to do it with ion rockets and very high velocity exhaust mass velocity to keep the exhaust mass total lower.

You would need to make many orbits (10,000?) about the sun with solar sail only to move out to 2 AU and that would take more than 10,000 earth years as as you get further away the orbit year period increases and the radiation pressure falls to only 25% of what it was at 1AU.

Again I note that "gathering ice" from space or rings of Saturn etc. with "robotic space tugs" is probably very "mass negative" - I. e. takes more mass for the turn around trip out and back from the colony ship than the tug can bring back. To take a historic example which may be different but not a 1000 times different: one gram of moon rock took more than 10 tons to collect and bring back to Earth.

SUMMARY: I may be thinking in the 20th century mode, but I am not ignoring physical laws and widely speculating as to what might be developed.

 

Billy

Some of what you say is correct, but some is problematic. For example, you said : "Mainly as you can not throw out ions but must neutralized them to avoid making net charge on the rocket and an ion attracting electric field which turns the ions around and makes them fall back on the rocket for zero net thrust."

An ion drive engine for a star drive, designed 1000 years from now can be assumed to be immensely effective. This means high exhaust velocity. A stream of charged ions leaving at in excess of 99% of light speed. For electrostatic forces to have an effect on slowing the vehicle, the ions would have to be very close to the vehicle (force decreases as the square of the distance). The time they would be that close would be measured in fractions of a femtosecond. ie. effectively no braking effect whatever.

I agree that solar sails will be of limited value further from the sun. But again, remember that this is 1000 years in the future. We can expect the technology to be very advanced, and solar sail performance much better than anything we plan for today. However, I agree it will be of no value once the vehicle has gone more than a few AU from the sun. That is when the ion drive takes over.

Actually, I suspect the 'departure point' will be somewhere in the Kuiper Belt, when the last of the extra reaction mass is taken aboard, which makes the solar sail at that point not useable. Instead, our space city will float alongside a Kuiper Belt object, such as a comet, to permit it to be mined.

You said : "To take a historic example which may be different but not a 1000 times different: one gram of moon rock took more than 10 tons to collect and bring back to Earth."

Naughty, naughty!
You are smart enough to know that this is deliberate deception. Leaving the gravity wells of both Earth and the moon to take on board a payload is more than 1000 times different to a vehicle beginning in solar orbit, and never touching down inside a gravity well.

Even the sun's gravity, to be overcome when leaving the solar system, is miniscule by comparison. All that is needed, in fact, is to slowly accelerate to cruising speed - perhaps 0.1C - and then drift till time for deceleration. This type of action is perfectly suited to an ion drive.

The time factor is large. If it takes 10 years to accelerate to 0.1C and 10 years to decelerate, then transit time Earth to Alpha Centauri is 55 years. Not too much of a problem on a self sufficient space city. Even less of a problem if, in 1000 years, human life span is greatly increased.