SkepticLance

A person with all the genetic predisposition to alcoholism might be raised in a society where alcohol is absent (like the pre-European Maori in my country), and thus never shows the symptoms. Is he an alcoholic? Obviously not, in spite of having all the characteristics that would have made him an alcoholic in our society.

Fossil fuels are useful, and sped human progress. However, they are not essential by any means. Before fossil fuels, lots of other fuels were used. Primarily wood. However, you can make fuel out of biomass by a number of routes, and some are very low tech. Producer gas drove cars way back in WWI. You can make liquid and gaseous fuels by anaerobic pyrolysis of wood waste or other biomass. You can make methane by tapping the results of anaerobic decomposition in rubbish dumps, as well as using the same process in a controlled manner in a fermenter. You can make ethanol or methanol as fuel. You can extract oils from plants. Fossil fuels will run out in due course and be replaced. They were not really needed to begin with.

With it weighing in at 6E21 tonnes, the energy to move the Earth significantly would be unbelievable. Anyone care to do the sums?

Mr Skeptic Noted. However, we got a long way to go. The current space station cannot keep people healthy for too long. A long term habitat will need gravity, shielding from radiation, a nuclear fusion power plant, and enough green plants growing to remove CO2, provide oxygen, and grow food.

Assuming the survival and continued growth and development - especially technological - of the human species, it is only a matter of time before we develop close-to-self-sufficient space habitats. Once they are up there drifting about the solar system, it is only a matter of more time before, for some reason we cannot guess right now, one such habitat and its denizens decides to make for another star system. With the right strap on propulsion unit (solar sails and/or a linear particle accelerator), a massive speed, possibly 0.1c, could be reached and Alpha Centauri is only 55 years away. Of course, it all depends on my initial assumption. Perhaps the LHC will make the black hole that will swallow the Earth. Bewaaaare. You have less than 6 months.

An advanced technology would have nothing to fear from meteors, since early detection systems would permit a very gentle sideways shove to make sure they miss. Edtharan is correct in talking about space elevators. They would make planetary colonisation much, much easier. I still am a bit sceptical, though. A space elevator from stationary orbit to Earth would have to be 78,000 km long (The ship at 35,000 km and the ribbon extending in to and out from the ship), and wide enough that meteor impacts would only create a hole - not destroy it. How heavy would a very strong and wide 78,000 km ribbon be? I suspect that the weight would make it totally impractical to carry, even on a very large starship.

Iridium metal is non toxic, but is a non starter because 1. It is incredibly rare and thus extremely expensive 2. It has an extremely high melting point, making it almost impossible to work. Your local jeweller aint got a dogs show! http://en.wikipedia.org/wiki/Iridium

iNow No-one denies that diseases of the mind are real. However, not all have measurable, organic, microbiological, degenerative or genetic causes. Some are, as I said, merely a case of being at one end or the other of the normal distribution curve for the trait being described. Others may be a result of aberrant learning. I am not sure whether the term 'disease' applies in those cases. For example : if a boy learns from his father that killing is OK, and becomes a murderer, is his ability to kill pathological? Or is it simply an unfortunate result of a perfectly normal process? What of an ex soldier who returns from war with a screwed up view of killing, and becomes a murderer? These are critically important questions, since they will strongly influence how we deal with such people.

Here is the situation. A space colony ship has left Earth and gone to Alpha Centauri. With 10 years acceleration and deceleration time, and a cruising speed of 0.1c, it takes 55 years. The ship is now at its destination. You are the captain. You were born on board, 15 years after the ship left Earth making you a vigorous 40 years old, and you were elected captain when the old guy died of old age on board. You look around the Alpha Centauri system, taking a few years to do it properly. You find a bunch of planets, and a whole lot of space debris. The only possible colonisable planet is similar to Mars. Cold. Toxic and very thin atmosphere. All the water tied up in very solid ice. A decision must be made. Do you, and the rest of the ship's complement, take on the whole business of colonising the planet, or do you stay in space, harvesting ice and debris to survive, and build more habitats in space so that the population may grow? Remember, you and almost all the others, are not planet born. Virtually everyone knows nothing more than living inside a space habitat. That is home, and 'natural' to everyone. To colonise the planet means parking in orbit around the planet, and shipping a small number of people down, to get them to set up a base. They have to harvest ice to refuel the lander craft for a second trip. They have to dig at least 10 metres under the planet's surface to set up underground habitats (if it is like Mars, the radiation levels at the surface will be long term lethal). The rest of the people on board will have to wait years till enough living room and enough lander craft capacity permits them to go down and colonise. They will live lives no better than in space, since they cannot leave the underground habitats except for short trips in full space suits. What do you decide? To commit to an unknown way of life with enormous restrictions, or continue to cruise around the planetary system, harvesting ice and minerals at need? Would you not be strongly tempted to continue with what you know best? I discovered many years ago how easy it was to get useful material from rock. I worked for a company that made mineral fibre by melting basalt in an electric arc furnace, and blowing it into strands. A by product of this was pig iron, which they sold. The Earth's crust is 5% iron by weight, and iron is very common in meteorites. A space habitat society would have no problem harvesting iron in vast amounts. Remember that we are talking about a society 1000 years or more in the future. The technology they have access to will be awesome.

If a person suffers from a 'difference' to other people, when that difference is harmful, but the difference is merely a case of being at one end of the normal distribution curve, can we call that a disease? For example : while I doubt that alcoholism should be called a disease in the scientific sense, there are definitely vast differences between individuals in terms of their susceptibility to addiction. If you are a person who has a natural vulnerability to addiction, you could well become alcoholic. After all, there is a proven correlation between a wide variety of addictions. If you are susceptible to one, you are also susceptible to others. Imagine you are at the far end of the normal distribution curve in susceptibility to addiction. Can we call that a disease? I am asking in terms of science. It may be ethically advantageous to call such a thing disease, but not scientifically correct.

To Mr Skeptic Just a small point. The maximum speed possible, according to current technology, is 0.2c, and even that is not terribly likely. Barring some breakthrough into currently unknown physics, 0.5c is simply fantasy. To Mr Crackpots Re extra-solar colonists staying off planets. The problem with treating planets as destinations is the sheer difficulty of fighting gravity wells. Today we have an enormous problem getting people into space, with the need for incredibly expensive rockets to lift mass into space. The cost will be something like $10,000 per kg to get mass into orbit. If we start out with a massive space habitat that travels to another star system, and an Earth like planet is found, then they will colonise it. However, the chances are that whatever is found will be far from habitable. It makes good logical sense to think that the star travellers will regard the gravity well barrier as too much, if and when the planets they find are utterly hostile. Remember that these are guys that have been in space for decades. Space is their home. We can expect that any star system will have the equivalent of rings and small moons around gas giants, asteroid belts, Kuiper belts etc. In other words, lots of ice and rock fragments drifting in space. Harvesting them will be easy. No gravity wells to fight. They can be used to build new space habitats for their expanding population. Fuel is deuterium from the ice. The rest of the ice makes water and reaction mass. Rocky materials provide minerals. As long as the population stays in space, travel to further destinations is easy. Drop to a planet surface, and you have a real problem. The planet will almost certainly be hostile - wrong atmosphere, wrong temperature, wrong orbit etc. To live there would be similar to living in space, in that you would have to build habitats screened off by massive metal walls from the surrounds. The only advantage would be an abundance of rock and (hopefully) water or ice. However, I do not think that will be limiting when in space. To terraform a new planet would take thousands of years, and why should you bother?

As I understand it, the energy carried by the neutrons is critical. You have to extract and separate the most radioactive isotopes, and expose them to the correct number of neutrons at the correct energy levels. This does not happen inside the reactor.

Just encountered an interesting article that suggests a neutron bombardment method might, in a couple of decades, be able to speed the decay of radioactive waste in hundreds of years. http://www.sciencedaily.com:80/releases/2008/09/080922100148.htm If so, this would be a great development, and would enhance nuclear fission as an energy source. Anyone got any further information?

I do not care much whether someone spells well or not. It is the accuracy and perception of their thoughts that count. I went through High School with a chap who was hopeless at grammar, spelling, literature and all the other aspects of the English language. He took two extra years to graduate High School since he could not pass the mandatory English section. At University, he thrived. Turns out he was brilliant at physics, and he used mathematics like his first language. Who cares that he could not spell. The guy was a genius!

Dak's statement that this is semantics may be correct. Can anyone give a better definition of 'disease'? I would be inclined to exclude anything without a measurable organic cause. ie. Psychosomatic and other behavioural afflictions perhaps should not be called disease. For example : Is morbid obesity a disease? I would be inclined to say no, since it is entirely created by an aberrant behaviour. It would be like someone attacking themselves by cutting chunks of their own flesh out, and calling the resultant wounds a disease.

A few points. The polynesians took 12,000 years to colonise the Pacific, with the Maori reaching my country only 800 years ago. The reason they took so long was primitive technology, and tiny destinations separated by vast distances. Star travel will not be the same, since we can see our destination. Interestingly, the polynesians grew sweet potato, which is a South American crop. They lived on Easter Island, much closer to South America than to their origin in Asia. They obviously visited South America also. The Sahara desert is definitely lived in and fully colonised. It is just that its water supply is low meaning a low carrying capacity - thus low population. The reason we do not live in Antarctica is international treaty. Inuits would have no problem living there. Indeed, neither would westerners, though they would be dependent on exploiting natural resources and trading for food. I agree with Moontanman in that humans will not need planets. And it is probable that most star systems will not have 'habitable' planets. Instead, we will live in massive space habitats, and harvest cometary debris and the like, for resources. Humanity probably will have practical nuclear fusion energy within 100 years. By the time we leave our own star system in about 1000 years, it will be highly developed. With abundant fusion energy, a space habitat of sufficient size and advanced technology just needs to harvest minerals. If our solar system is typical, we can expect massive amounts of these in asteroid belts, Kuiper belts, and in moons. Time to travel : if the NASA scientists I quoted are correct, our speed will be 0.1 to 0.2c. If we assume 0.1c cruising speed, and 10 years to accelerate to that speed, plus another 10 to decelerate, the time to get to Alpha Centauri will be about 55 years.

To iNow Not so much of the "you", please. This began with a review of a book, and I reported on the book's ideas. A big reason for posting this is to see what other people think, and whether Greenberg is on the ball or off the planet. Are these complaints definable as disease? I think that is a valid query.

I was reading a book review on the new book :"The Noble Lie" by psychotherapist Gary Greenberg. http://www.overcomingbias.com/2008/09/noble-lies.html He has some interesting cases of 'diseases' that are recognised as such but which are not diseases by any scientific definition. Classic example : alcoholism. There is nothing in science to make this a disease. It has no clear causative agent. No pathogen. There is no remedy. The decision to call it a disease appears to be purely a moral, not scientific, decision. It has proved to be a very good decision, helping millions of people - but is not science. Homosexuality is the opposite. It was once defined as a disease, but in 1973, as a result of political pressure, was removed from the Diagnosis and Statistical Manual of Mental Disorders. It now appears to be more regarded as a lifestyle choice, though I am not comfortable with that classification. Depression is widely regarded as a disease, though it lacks scientific criteria for that classification. Opens up the question : How scientific is medicine?

There was an article in Scientific American about 12 years ago by a couple of NASA scientists on travel between stars. There are definite limits to speed. We cannot go faster than light, based on current theory. If we want to travel at a high fraction of light speed, we will fail. We need to carry enough reaction mass to decelerate from our top speed. The NASA guys suggested that, in about 1000 years, we should be able to construct starships able to travel at 0.1 to 0.2c. Based on this, and a few other numbers, it is possible to calculate how long it will take to colonise the entire galaxy. Population growth, it turns out, is not much of a limit. Humanity can reproduce faster than we can spread. The main limit is speed of starships. Depending on the assumptions in your calculations, the galaxy can be colonised in a time varying between 500,000 years and 10 million. For example : If we assume an advanced culture that can carry frozen embryos, which will be thawed and developed by long lived computers/robots, and a speed of 0.2 c, then the first starships can get to the far side of the galaxy in 350,000 years, assuming they can follow a direct route. If the world is dominated by colonisation fanatics sending out vast numbers of ships, and the star born descendents follow this fanaticism, then total colonisation in less than 500,000 years is theoretically possible. This is, of course, unlikely. The real total colonisation time is likely to be far greater.

To blazarwolf, re random clumping. If you do not believe it, do the experiment yourself. Random distributions are not even. They are 'clumpy'. This is a result of chance alone. The idea that randomness equals evenness is only a fallacy of the human mind. Psynapse talking of little brother is simply mentioning an example of this clumpiness. One individual seems to get more good luck than his share. Others get less. The danger, of course, comes from Little Brother relying on this good luck, because his chances of being lucky next time are exactly the same as for anyone else.

No way!!! When doing something for your girlfriend, to be your fiance and then your wife, never, never, never do what appeals to you. The answer is to think about what appeals to her. Forget your own ideas. Think about her special interests, and especially anything that relates to something the two of you did. When I got married, I did something my wife still loves 20 years after the wedding day. We met due to a mutual interest in the sea (I won't go into details). She thinks of the mutual marine interest as very romantic. For our wedding rings, I got a jeweller to design the rings with black coral inserts and a wave pattern on the ring to commemorate our meeting. Get romantic. Forget your own quirks and do something for her.

If we define luck as being random chance, then I would like to mention a common misconception (of course, not held by any of the highly intelligent and rational people on this forum). Random chance operates in a manner describable as 'clumping'. If you toss two dice, you get a result between 2 and 12. If you record the results over, say, 2,000 throws, you can plot the results on a graph. Every time you throw the two dice twice, use the results to put a dot on a graph, with the first result on the X axis and the second on the Y. Most people expect that the long term result will be a spread of dots that are pretty even over the graph. Not so. In fact, the random result is dots that appear to be 'clumped' into groups. This 'clumping' has effects that gamblers are well aware of. They call it a 'run of luck'. If playing poker, for example, you can get a bunch of superb hands, followed by a bunch of terrible hands. This is still the result of good shuffling and hence random selection. Where gamblers go wrong, of course, is in assuming that a run will continue. It does not matter how many good hands you have received, your next hand has a random chance of being good or bad.

The problem with statistics and other numerical evidence is that it is misused or ignored. There is no better evidence of a rational kind than hard data expressed as numbers. This includes statistical data with its pre-calculated error factors. However, we are faced with a wall of ignorance on how to use such data. I have even encountered people who say : "It's only statistics." As if that meant those numbers could be safely ignored.

There have been a lot of scientists researching possible health effects of EM radiation. To date, the result is zero. EM will not cause harm to human health, even at levels experienced by people who live under high voltage power cables. The reality is that your problems almost certainly have a different cause. You will receive more harm, by far, from the psychological effects of worrying about EM than the radiation itself can ever deliver. There are, for example, a bunch of viruses that can cause ailments with symptoms like yours. Not much you can do about them, except maintain a healthy life style. They often disappear in time, as the human immune system finally gets on top of them. I recommend you consult a medical virologist. And avoid quacks.

There was a snippet on this in New Scientist some months back. They agreed with the mutation idea, and suggested that the recessive gene became so common due to sexual selection. Remember the song? "Beautiful, beautiful blue eyes."