SkepticLance

There is nothing simple, or black and white about current middle East conflicts. Al. Qaeda, in all its evil, came into being in response to historical ills. Much dates back 1000 years, to the crusades. In the Muslim Middle East, the word, Crusader, is a dirty - even foul - word. To call America in Iraq a bunch of crusaders is to call them evil, in the worst possible way. A more recent problem is that festering sore known as the Israel/Palestine problem. That was based on a totally evil act by America and Britain. For over 1000 years, Palestine was home to a people who were Muslim. After the holocaust, the west decided to solve the 'Jewish problem' by giving them a home. However, the homeland was occupied. No problem! The Palestinians were unceremoniously turned into refugees. Naturally the Palestinian's descendents, and other Muslims did not take kindly to this, and they fought back and still fight back. I do not agree that killing innocents is a valid form of freedom fighting, but I definitely understand why they are fighting. Until America addresses this situation, there will be enormous hatred of the USA throughout the Muslim world, and that will translate into terrorist actions against America. There is only one way to ameliorate the problem. America must put intense pressure on Israel to return the conquered territories to Palestine, and establish a truly independent sovereign nation. America must then pour aid into this new nation to get it onto its feet. Such an act will serve to defuse the hatred Muslims feel. Of course, there is no easy fix, and even this will not cause Al Qaeda to disappear, or to stop Iran developing the bomb. However, it is a really good start. One thing that the USA should have learned by now is that aggression begets aggression. 650,000 Iraqis are now dead as a direct result of the Iraq war. Three times the number that Saddam killed, and in a much shorter time period. Al Qaeda will strike again. More Americans will die. Self defense is justified. Wars of invasion are not. And they bring retribution, even to superpowers.

You Northern Hemisphere types! You don't even know it, but your seasons are around the wrong way. Here in the real world, we have just come out of a terribly cold winter - worst for 30 years. Today is a glorious spring day. Sunshine, and the sea is blue and calm. Looking forward to summer in just over a month!

BigMoosie is correct. The answer is no. Sol is not part of a binary system. I suspect the idea may have arisen from certain theories that our solar system was influenced in its development by the gravity from another star passing close. However, even if this was true, it was never part of our system.

For those who are interested, it has been calculated that life on Earth will go extinct in less than 500 million years. This is due to the sun heating up, to the point where the entire planet gets a lot hotter than 100 C. The sun will swell and actually engulf the Earth in about 5 billion. Most life on Earth will be gone in 400 million, with just a few extremophiles left. This is a small time period against the 3 to 4 billion years life has existed. If humanity survives long enough, though, Earth life should by then be well established on other worlds.

tejaswini NO genetic modification is about to be applied to humans. If we ever GM humans for greater radiation resistance, it will be 50 years plus in the future. I have enough belief in the power of increasing knowledge to accept that, by then, we will know enough not to create terrible side effects.

Drinking blood is actually pretty safe. About equivalent to eating a rare steak. The Masai have been doing it for thousands of years. Only problem is that it is not very thirst quenching. Trying to heat blood for some kind of distillation aint that easy. it has a habit of cooking. Even seen blood pudding? It is not liquid. If you have all the equipment needed, there are probably a lot of alternatives. You can distill water out of all sorts of things, from damp dirt (just dig down) to green leaves. You can even get water direct from the air by condensation. Early morning, the air is usually 'damp' compared to the air's capacity to hold water. It will condense on cold surfaces. Glass is best.

'Slower' is a relative term. It is only a matter of seconds from adrenal gland to brain. In the mean time, you have just had a severe fright. Your brain is in overdrive. You do not notice that adrenaline has not yet kicked in. When it does, it seems to be just a part of the total reaction.

aj I have travelled widely, but am not prepared to make recommendations till I know what you want. What is it that really blows your hair back? Are you looking for arts and architecture, nature and outdoor activities, new people and cultures, sports and adventure etc, etc.

I think Skye is correct. It is a bit like calling Pluto a planet. Might have a little utility on the populist basis, but little meaning scientifically. Amoeba and Chlamydomonas are not really related. So why call them both protists?

lucaspa. You are niggling me because I a suggesting a range of possible motives for going interstellar. We are talking about possible a million species and 2 billion years. There are possibly thousands of different motives for going interstellar. Any of them will do. the data does say that an alien species never made a LONG TERM -- billions of years -- colonization of earth. If they had, they would still be here! BUT, it doesn't discount a complete colonization of several million years For God's sake, lucaspa. If a species was on Earth one million years, it would leave so much garbage that we would be living in their land fills! Yet we have not found a single artifact. And please don't throw crackpots at me. Their hypothetical artifacts would not fool a five year old. Right now, we have NO alien artifacts. Let's forget moties. It is fiction and thus irrelevent to the discussion. Now, also remember, in order to undertake the interstellar trip, they must have population control. Otherwise they will starve or use all the breathable air. Between the stars, there is no source of new air -- no recycling system can be perfect (second law of thermodynamics). So what you have is all you've got. Population growth exhausts those resources and everyone dies. So, in order to even consider an interstellar trip, they have a means of controlling their population. Not so. As pointed out earlier, a trip from Earth to Alpha Centauri at top speed 0.1c and acceleration of 0.01G would take about 50 years. If our hypothetical species doubled its numbers in 50 years without control, it is simple engineering to make the space habitat/city big enough. However, I am suggesting a species that controls its numbers when it must, and multiplies when it can. Are you telling me that such a species is impossible when we talk about a millions species over 2 billion years. I don't think so.

lucaspa said : 1. Moving the pollution doesn't really solve anything, does it? Since it is atmospheric pollution, it is going to get to you eventually. What we need is fusion power. Then we would have enough cheap electricity to hydrolyze water for hydrogen. Until then, the current methods of cooking coal just makes more pollution. 2. There are ways now to keep the hydrogen bonded to porous metals -- titanium is one, I think. Thus, you don't really have a pressurized gas in a fuel cell like was in the bags of the zeppelins. No more danger of explosion than you have with gasoline powered cars -- maybe less. On point 1. Dak is correct. Controlling pollution in a factory is easier than in small motor vehicles. Nitrogen and sulphur oxides can be scrubbed out. In the near future, carbon dioxide will be pumped into very long term underground storage. Some researchers are even working on ways of bubbling the carbon dioxide through ponds filled with algae to remove the nasty gases. Fusion power would be lovely. However, no scientists working in the field suggest it would be available before 2050 at the earliest. See the latest (September 2006) Scientific American for a good article on this subject. Point 2. Hydrogen storage by metal bonding is a great idea, but it is not yet available. At this point in time, we can only use tanks. Probably high pressure storage of gas. Cryogenic storage is also possible, but is much more high tech, and not really suitable for motor vehicles.

Dak said : skepticLance why not just make and store electricity when the wind's blowing, and use it when it's not? Mainly for reasons of efficiency. It is possible to do what you suggest. For example, a wind farm can pump water uphill when the wind is blowing. When the air is still, the water can flow back down through a turbine to generate power. The problem is that a very large percentage of the energy is lost in the process. That is not the best way to use wind energy.

lucaspa The coal to hydrogen approach is only one way of doing it, and as you said, not a smart way. We can, however, make hydrogen from many sources. The cleanest is the electrolysis of water, if the electricity is generated in a clean way. eg. nuclear or wind. I think this is the best way to use wind power. Simply hooking up windmills to electricity networks is not smart, since wind power is too variable. However, using wind power to split water to make hydrogen is much better. Make and store hydrogen when the wind blows. When it does not, use the stored hydrogen.

JesuBungle said ; But in the Boron process, where does the steam come from? The water has to be heated somehow... The New Scientist article said that the process would be started with a car battery. Just like current starter motors really.

JohnB said : Sceptic, you're not going to the "Fine Foods" show in Melbourne are you? Wish I was!. Food is not my profession, but I am an enthusiastic amateur. Lucaspa said : Your argument on the presence of alien artifacts rests on the assumption that the geological record is complete. Of course not! I have a degree in biology and a good understanding of fossilisation and its consequences. Probably only one organism in a trillion or less ended up as a fossil. There are heaps of gaps. What I am saying is that if an alien species is living on Earth, it will inevitably leave vast amounts of materials (garbage) that is non-biodegradable - hence prime candidate for preservation. The vast bulk of that rubbish would never be discovered. However, it is inevitable that at least a few bits and pieces would turn up. Haven't been paying attention to the immigration debate, have you? It's not "small numbers" of illegal immigrants we are looking at. Nor was it "small numbers" of Europeans that came to America in the late 1800s. Everything in this world is relative. My use of the term 'small numbers' was clearly misleading. Sorry. The small size of those numbers is relative to the large size of the numbers left behind. Unless there is something massively traumatic (like the Irish potato famine driving people to America) the percentage of those emigrating is small. That's not true. You shouldn't try to fib about the book. There were representatives of each subspecies on the ship -- in frozen sleep. There was only one conscious Motie -- a Mediator. Sorry again. I meant one ship, of course. It is a while since I read that book. We should not forget that it is fiction. I do not believe for a moment that a species as immensely capable as the moties could remain trapped on their world as Niven describes it. We can't afford to build an interstellar generation ship. We have the basic technology if we used the Orion drive. But no nation can afford it and, quite frankly, the taxpayers wouldn't cough up the money. And we have population pressure, don't we? Our discussion recently was in relation to a world that already had a Dyson swarm. The economics in that situation are simple. In spite of your assertion that such a habitat is not a generation ship, it would, in fact, be relatively easy to convert. Essentially, all that is needed is an independent energy source such as a fusion generator, and suitable size ion drive engines (or some futuristic equivalent) strapped on. The habitat is already set up for long term survival. Each habitat, for the economic reasons you are so fond of, will be large, and will be independent in terms of food and oxygen generation (assuming they are oxy breathers). If they follow a pattern similar to human, each will have a leader, or small group of leaders. Again, if they are similar to humans, it is inevitable that charismatic leaders will appear from time to time, and some of them, for religious or other reasons, will promise to take their people to a promised land. If they are very dissimilar to humans in terms of motivation, then their actions are quite unpredictable, and they might do almost anything for reasons beyond our grasp. If, over a 2 billion year period, there are very large numbers of such species, then at some stage, this diaspora will occur. If, on the other hand, the species we are discussing, never gets to the stage of building a Dyson swarm, then there is every chance it will build space habitats anyway. When that happens, they will move those habitats to where raw material is available. Their equivalent of asteroid belts, Saturn's rings etc. I have never been terribly convinced by the idea that an advanced species will hang about in the equivalent of Earth orbit to collect energy. With advanced fusion generators, energy is not the limiting factor. Anyway, for extra-stellar travel, all that is need is space habitats/cities. They do not need to be part of a Dyson swarm. Once you have Dyson swarm habitats, you have no MOTIVE to go interstellar! Today, there are more people living in Europe than there was 200 years ago, showing that there was room for more people in Europe, at the time so many were leaving. Yet a lot of people left Europe to go to unknown and potentially hazardous places to live. Motive is more than just; "have I got room to live, and enough bread on my table?" Remember, it is always a small percentage that leaves. It is always the most adventurous and entrepreneurial that do so. Motive comes from those factors, rather than dire need. Swansont said : (aliens didn't make it here; if they did, traces were not preserved) Those are the points, aren't they? However, if aliens are large in number (and remember that Sagan and Drake estimated one million species currently living in our galaxy), and bearing in mind the 2 billion year time frame, it seems impossible to me that they would not make it here. And not just one species. It they did, and did not leave traces, then it must be because they left immediately. And why should they do that? After all, it would take them at least 50 years to get to the next destination, and Earth would be a prime candidate for colonisation. It must be our assumptions at fault. ie. We do not have one million species, or any large number.

Sisyphus said : Definitely interesting, but doesn't it seem less practical than a simple fuel cell? Or maybe the advantage lies in the boron not needing to be replaced very often, and so the equivalent maintenance to fueling up is literally just pouring water in the tank... The main alternative to the boron plus steam idea is to use straight hydrogen. However, there are enormous problems with storage and transport of the gas. Trying to keep a tank full of gas in your car is both dangerous and wasteful. Hydrogen gas will leak out of the tiniest gap. Using boron metal makes the whole thing much easier.

According to New Scientist, it is possible to make a 'water powered' car, using boron metal as the energy source. Works like this. Boron metal as a powder has steam passed over it. Reduces the water, leaving hydrogen gas, which runs the car, probably by a hydrogen fuel cell. When all the boron is depleted, it is returned to a regenerating plant, which uses energy input (eg solar from mirrors) to reduce it back to boron metal to re-use.

I am sad to see that this thread is starting to get a bit silly. A lot of arguing is going on about matters that are not relevent to the earlier theme. For example : some of the comments about fossils are just plain ridiculous. It is widely accepted among professional palaeontologists that the reason for minimal fossils before 600 million years ago is lack of hard body parts. Some of the other arguments on this are based on local examples without wide or general application. If aliens had once occupied Earth, it is possible they 'camped overnight' and left no markers. If so, why not a second race, that colonised? Such an occurrence would have left billions of hard remains that would be likely to form fossils. How many coke bottles alone are thrown away each year? To suggest aliens came here and left no traces is ridiculous. Lucaspa mentions corals and koalas. Both have means of dispersal. Look it up. Admittedly koalas method is slow, and inefficient, and not well adapted to Australia after the impact of humans. The question of the effect of population pressure. Again, I wonder if I am not able to communicate. There seems to be a wide divergence in perception on this question. Population pressure causing geographic dispersal does NOT operate on large fractions of the species. It works by influencing very small numbers to get the hell out of there. It is always a small number of pioneers, while the vast majority stays home to face the consequences. Even in Larry Niven's 'motie' books, the only case of a motie emigrating was an individual, while the bulk of moties stayed home and died. This is the way it works in real life. A few pioneers leave, and establish new communities elsewhere. It is NOT an explosion of emigration. Lucaspa says Dyson swarm habitats are not generation ships. Quite the contrary actually. They are IDEAL generation ships. Just a couple of modifications. Lucaspa argues against the 6 billion year time frame. That is not my idea. It came from an item in New Scientist, based on astronomers findings. 10% of our galaxy consists of third generation stars 6 billion years old or more. That is not a matter open to debate. it is a scientifc finding. Swansont points out a problem with my communication of wealth/population growth. Sorry. I was trying to say that, if cost was a limiting factor on numbers of kids, we would expect the very rich to have more kids. Of course, that is not true. I will be going on a month long business trip in a couple of days, and will not be contributing to this (or other) threads during that time.

Edtharan. Much of your reasoning on the population growth question is based on an "All or Nothing" logic. That is, you suggest that EITHER - The population growth is totally controlled, so that no expansion is needed OR - Population growth is uncontrolled and will expand until disastrous collapse. Now, bear in mind that we are talking about intelligent and technologically advanced beings. An intermediate state can be achieved. If the aliens know thay have to control their numbers, but also have the desire to have more than two offspring per two parents, then a compromise condition can be organised. That is, population control is used with reluctance when needed. Population growth is eagerly embraced when possible. Such a state would render your reasoning invalid. Lucaspa said : After all, you need to get the wealth necessary to build a generation ship. Not to mention all the R and D to get to the point where you can build a ship. We have already got past this point in discussion. I was arguing about what is likely to ahppen AFTER the aliens had achieved a Dyson swarm. The habitat now already exists. And don't forget the wealth necessary to support them. As individuals get wealthier, kids cost more. So, the cost of children is such that a couple can only afford two, if they are to raise them in such that they have a chance to do well and reproduce. This is somewhat unrealistic. You only need to look around you. People do not always decide on numbers of kids by careful logical reasoning. The final numbers are likely to be the result of emotions, not logic. Your faulty logic implies that very wealthy people will have more children. In fact, on average, poor people have more children. If we look at third world nations, and their fertility, you will find it inversely correlates EXACTLY with access to contraception. When people have ready access to contraception, numbers of offspring per couple drop, to western nation levels. Thus, it is not wealth that determines numbers of children. You may also be able to tack a solar sail, like you tack a sailboat to move into the wind. That much I know for sure is not true. It is possible that a solar sail may be tacked, but only by a mechanism totally different to a yacht moving through water. I speak as a yachtie. It is only with the use of a keel, centreboard, leeboard or similar that a water yacht can tack. That device is needed to prevent sideways slippage. A solar sail vehicle travels in vacuum, and cannot have a keel or equivalent. Lucaspa said : Actually, stars have existed in the Milky way for 10 billion years. But there is another hidden assumption here: the elements available to planets of first generation stars. Our ability is predicated on heavy metals. First generation stars and star systems are metal poor. So they don't have the basic material necessary to make the equipment necessary. Correct. However, when I talk about 6 to 8 billion year old stars, I am talking only about third generation stellar systems. Roughly 10% of the Milky Way galaxy is third generation stars at least 6 billion years old. Any intelligent species that developed on these systems is likely to have a 2 billion plus head start on Earth. This is so completely wrong! Successful species are actually in balance with numbers. Population remains constant. There is always some population loss, and this is generally quite large. If a population stays at a relatively stable level, it is due to the unbiquitous tendency for the population to grow. In other words, more than two births per pair of parents, to permit compensation for the high death rate. As soon as a species develops to the point where it reduces its own mortality, this drives population growth, which is thus the 'natural' state. Have you read or heard about all the gaps in the fossil record? Yes, we do have fossils from 3.8 billion years ago -- in one small location. Do you think that was the ONLY place life was on earth? But we don't have any fossils from anywhere else, do we? Again, faulty logic. It is true that the numbers of fossils reduce dramatically pre-Cambrian (older than 600 million years). But this is not due to the age of the rocks so much as due to the fact that hard structures were uncommon in living things at that early stage. The oldest 'fossils' are 3.8 billion year old hydrocarbon traces in some Canadian rocks. At that point in the history of Earth life, only very primitive, almost non-life, was likely to exist. Thus no true fossil. The oldest hard fossils are some stromatolite fossils from Western Australia at 3.6 billion years. However, even this is tricky since the hard parts are simply sand grains cemented together over the bacterial colony. Thus, these fossils are controversial. Once living things began forming shells etc, the fossil density dramatically increased. In the 500 to 1000 million age group, a number of fossils have formed from impressions in fine mudstone. eg jellyfish. However, without hard parts, such fossils are rare. Any alien species living on Earth would have left hard structures. Thus, they would have left traces.

Swansont. Thanks for that. Belatedly, I realised the same thing, but too late for my posting. That is good information. Thinking about sayonara's swarm... The swarm MUST be made up of spinning cylinders or similar. Atmosphere could not be kept on the outer side of moonlets or the equivalent of moonlets. Thus, the swarm will end up as cylindrical habitats/cities, or some similar concept. They would not form a sphere as such due to orbital problems. Instead, we would see a whole lot of 'ringworlds', each made up of perhaps a million habitat/cities. The ringworlds would all have to be a slightly different distance from the centre star. Thus, the description of this set up as a bubble or sphere is, in fact, incorrect. If the population continues to grow, eventually even that system will lack capacity for all the individuals. The logical next step is to equip habitats with fusion power plants so they can move further from the central sun, and be independent on stellar power. Having got to that stage, there is nothing to stop them travelling inter-stellar.

Sayonara. In earlier postings I have suggested two reasons why a species will move away from its sun. 1. The explorer instinct. If it is Earth humans, then we know from observation that this affects a minority of people, but very strongly. There would always be a certain number of people who would fight for the chance to go elsewhere. Some alien species would be similar. 2. Population pressure. If the species involved continues to grow in number (and evolutionary principles suggests that a desire for more than 2 offspring would be a selective advantage), then even a Dyson swarm would eventually be unable to support all of them. And again, I have to say, that if the number of alien species is very large, then at least one will act in just that way. Also, Sayonara, you have not responded to my quibble about gravity. Your Dyson swarm would have to be spinning structures, with the people inside, since there would be too lttle gravity to hold an atmosphere outside. Edtharan, I think you are right in your suggestion that reaction mass would be needed. Correct me if I am wrong, but I cannot see how a solar sail could be used to move inwards towards the sun, which would, in theory, be needed as often as a move outwards.

Sayonara. You still have not answered the gravity query. If your Dyson bubble is actually made up of quadrillions of small islands in space, like a swarm of asteroids, then they will have insufficient gravity. They could not, for example, hold an atmosphere. It takes a much larger mass to retain air. For example; Earth's moon could hold an atmosphere for about one million years. By then it would have all bled into space, and your swarm of objects would have to be much smaller than the moon, assuming 3 million or more objects from the mass in a stellar system. If your 'bubble' was built, logically, the islands in space would actually be the spinning cylinders I suggested. The people would live inside the cylinders, and sunlight would be collected on the outside. This is just a very minor extension of what I said a long time ago. That humans in space would build lots of habitats/cities to live in. Your Dyson bubble is simply a hell of a lot of those habitats, at one astronomical unit from the sun. If we are, in fact, building spinning cylinders, why not go the one logical step further, and install fusion power plants? Then they would be independent of the need to stay the correct distance from the sun. They could travel to any distance from the sun, or even to other stellar systems.

Sayonara. Could you inform me on one point, please? You talk of Dyson bubbles instead of spheres. I assume from that, that we are talking about a very thin wall. If that is true, from whence comes the gravity? Clearly, a ringworld can provide gravity from spinning. A sphere or bubble cannot. I assumed sufficient thickess in the walls for sheer mass to provide gravity. If the walls are thin, how does that work? Incidentally, a thick walled sphere would require enormous mass to be brought in from other stellar systems. Sayonara said : The other function is to provide living space which can be expanded into and added to as and when required. True. However, converting the mass of a stellar system into spinning cylinders will provide even more living space. Unless, of course, you have only enough mass to make a bubble. In that case, refer to query above. I invite you to try living on any given Kuiper Belt object for a week. Your kit bag will include antiseptic cream, 2l bottle of water, packet of tomato seeds, bag of air. Please explain the relevence of this comment. but in terms of resources per unit population supported you will be using more matter and energy than you would with a Dyson Bubble. Actually, the opposite is true. A Dyson sphere or bubble cannot trap all the energy emitted. It MUST vent most of it out to space, or else it would become a furnace. A cylinder using fusion power can save energy by generating only what is needed. A star is an uncontrolled source of energy. A fusion generator is under your control. I am, of course, assuming a very advanced technology that can tap all the fuel reserves of a star, and maybe this is pushing our speculation too far. However, I think a Dyson sphere/bubble is a pretty big push already. Because you don't really need to. And even if you continued to build and breed quite rapidly, under those conditions your expansion into the local systems could progress at a very leisurely pace without sacrificing any comfort. Here we are back to matters of motivation. Again, I have to say that you may be right if the number of alien species is small. However, if there are enormous numbers of species, some will be expansionist in motive. That becomes highly probable statistically. Imagine our own species in your scenario, living on a Dyson bubble. Do you really think there would be nobody wanting to shoot off into unknown territory to explore and colonise?

I agree with Edtharan that Dyson spheres are not practical. First because they are not stable structures with respect to the central sun. Second, because the enormous effort involved in the building. The amount of energy, time, effort etc is beyond human comprehension. And third, because it is totally unnecessary. The whole rationale of the Dyson sphere (ringword or whatever) is to tap the energy of the central star. Once efficient fusion power is available, this becomes utterly pointless. A Dyson sphere requires a very thick shell in order to have enough mass for gravity. If you have that much material, why not, much more simply, have the mass as hollow cylinders, spinning for gravity, and powered with fusion generators? The total living area for the amount of mass used would be far greater than a Dyson sphere. The use of the mass would be far more efficient. In fact, in terms of efficiency (the number of sentient lives that can be supported per unit mass in a stellar system) it would be far more effective to dismantle the sun - pull it apart and trap the rapidly cooling hydrogen. If a species is capable of building a Dyson sphere, they can dismantle a sun. eg. use enormous magnetic fields to pull the hydrogen into massive flares, which, out in space, are trapped by Bussard type magnetic fields, except powered by fusion generators. After all, if we speculate about the power to create Dyson spheres, we can speculate about what else such a civilisation could do. A planetary system converted into quadrillions of giant spinning cylinders, and a sun dismantled for hydrogen fuel to drive fusion generators, would support far more sentient beings for far longer than a Dyson sphere could. And then, once the species had got that far, why not send those cylinders to all corners of the galaxy to colonise? A sun will fail after, say, ten billion years. The alternative will last as long as the galaxy does.

Sayonara. Correct me if I am wrong. Are you someone who believes that the ultimate strategy of a highly advanced species is to build Dyson spheres? You should be aware that such spheres are detectable by astronomers. The heat put out by their suns must be permitted to dissipate, or else they would all die a heat death. The most likely such dissipation is as infra red, which can be picked up by our infra-red telescopes. Apparently, there would be a clear cut spectral signature for such an infra-red source. Thus, we could identify any Dyson spheres anywhere in our stellar neighbourhood. True, we would not do so for any sphere at an exceptional distance from us. However, again harping back to my theme, if the number of alien species is very large, thus meaning many Dyson spheres, we would already have detected them.