Newtonian ships or not?.

[Roanon]

Originally posted by JurijD:
you could colonize the entire galaxy in a couple 100-thousand years...

100 to 1,000 years? 100,000 years? Oh well, what are a few powers of ten among friends...

[geoschmo]

Originally posted by JurijD:
so the real question is: why hasn´t anyone done it yet) how come I don´t have a weird little green man for my neighbour... no wait I do.. at least the weird part

There are many possible answers to this question.

It's possible we are alone, although I think it's very unlikely.

It's possible that there are others out there, but none as advanced as us. Again, I think it's an unlikely possibility.

The most likely possibility I suspect is that your assumtions are overly optimistic. It may in fact be much much harder then you you think to travel between the stars. Without some major breakthrough that we can't predict or plan for, it's very unlikely that we will progress in 100 years to any sort of technology that will allow for reasonable travel times. If it takes centuries to get to the nearest star, then it becomes much more difficult to build ships that can stay together long enough to get us there alive. We aren't even sure yet how will overcome the damage to our bodies living in space for the few months it takes to get to Mars. Not even considering the prospect of our ships wearing out.

Assuming we can get there, you are wanting the people you sent to get right to work building another ship. This of course will have to be built entirely from local materials. Which means a lot of infrastructure work building factories and extracting resources, on top of whatever needs to be done just to survive in their new environment. What will be the impetus driving the colonists to send ships to another system? Wouldn't many of them be more interested in exploring their new planet and system? Making a life for themselves?

I am sure eventually they will get to the point of sending out another ship, but 100 years seems very soon to me.

If we do not make any sort of tremendous breakthrough in travel speed, I think it will be a very long time before we leave our own star system. For one main reason, why go? If you overcome the problems with living in space for long periods of time, and can build the size of ships that would be neccesary to send thousands of people to Barnards Star, why not build an L5 colony instead? Or a domed city on Mars, or an undersea city on Titan? There are a lot of interesting places to go right here in our own solar system. And there's lot's of room to expand. It will be quite a while before we run out of room. You could get your fill of exploring new and interesting places, and still be just a few months or years from mother earth.

[geoschmo]

Originally posted by Roanon:

quote:

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Originally posted by JurijD:
you could colonize the entire galaxy in a couple 100-thousand years...

100 to 1,000 years? 100,000 years? Oh well, what are a few powers of ten among friends...

---

Actually there's not much difference in this case. If is his basic assumtion is correct, that a new colony could send a new colony ship in 100 years, and additionally we assume that it takes an average of 100 years for the each colony ship to reach it's new home, we could colonize the entire galaxy in less then 4000 years.

That's about the length of recorded human history. But even if he meant it would take 100,000 years, considering the age of the galaxy we should be seeing someone out there. So either we are alone, or they don't want us to know they are there, or it's a lot harder then we think to get around out there.

Geoschmo

[Baron Munchausen]

Not only travel but simple survival in space might be more difficult than we realize. It's amazing to think how little we really know about space travel. Only the dozen or so men sent to the Moon in the 1960s and early 1970s have ever been outside of the Earth's magnetic field. And that only for a few days. Everything else we think we 'know' about space travel is speculation from SciFi.

Just about every single lunar astronaut had some sort of psychiatric problems when they returned. You could easily assign this to 'stress' of course. They had been on a very dangerous mission (think of the creaky little tin-can space ships they traveled in!) and were trained very rigorously, so being released from that pressure and sitting back and realizing what a dangerous thing they had done could have had an effect on their mental stability.

But we don't have access to their medical records. Only the US Government has access to all of their medical records. I've seen some NASA people post on other discussion Boards that the 'real reason' we haven't returned to the Moon is classified. In other words, it was not simply budget reductions. There was a real reason that the Moon missions stopped. Could they have noticed something in the medical information about the returned astronauts? Were they affected in unexpected ways? Maybe life here on Earth has some important relationship with the magnetic field and leaving the earth's magnetic field unbalances something in our biology? Changing your home might not be as simple as jumping from one rock to another in space. Life processes could be dependent on other factors that we haven't figured out yet. We may be part of this planet in a way that we cannot change.

[ March 28, 2004, 00:30: Message edited by: Baron Munchausen ]

[President_Elect_Shang]

Good point Baron, and I am not criticizing but I want to point out for those that may not know, the moon is not outside of the earth’s magnetic field. With that in mind what you [Baron] say is very important. If this was the effect on humans that where under the influence of the moons, sun’s, and the earth’s magnetic field what would happen when the only influence is that of the sun? A little confused by what I just asked? Think of migratory birds and many other creatures (insects, mammals, reptiles, etc) and what happens to them when scientists have tinkered with their heads.

I should also point out that even though we are under the influence of the moons gravity I was speaking specifically of the reverse: More moon, less earth.

[ March 27, 2004, 20:38: Message edited by: President Elect Shang ]

[Baron Munchausen]

The Moon is well outside the normal reach of the Earth's magnetic field. There is a 'tail' extending away from the sun, because of the solar wind, which the Moon might enter at certain times when it is on the far side of the earth from the sun, but normally it is well outside the field.

http://en.wikipedia.org/wiki/Magnetosphere

On the sun's side of Earth, the magnetopause distance is approximately 10 Earth-radii. Abreast of the earth the distance grows to about 15 earth radii (distances change with solar wind pressure and density; The magnetosphere is made to flap and compress by the solar wind) while on the night side it extends into a long cylindrical magnetotail at least several hundred radii long, gradually turning into a wake.

Since the earth's radius is about 4,000 miles that makes the magnetosphere about 40,000 miles on the sun side and about 60,000 on the trailing/leading sides. The outward side is obviously highly variable but the Moon doesn't orbit exactly on the earth's equatorial plane so it won't necessarily contact this tail even when out the outward side of its orbit.

http://www.enchantedlearning.com/sub...tosphere.shtml

William Gilbert hypothesized that the Earth was a giant magnet in 1600. Thomas Gold proposed the name "magnetosphere" in 1959. The Earth's magnetosphere extends far into space and is influenced by the solar wind (ions and electrons emitted from the sun). It extends into space from 60 to 37,280 miles (100 to 60,000 km) towards the Sun, and over 186,500 miles (300,000 km) away from the Sun (nightward), forming the Earth's magnetotail.

The Moon orbits just about 220,000 to 250,000 miles from earth so it would only rarely enter this 'tail' when it was at its most extended.

[ March 27, 2004, 21:15: Message edited by: Baron Munchausen ]

[President_Elect_Shang]

ACK! Now how did I transpose the meanings of gravity and magnet? Gravity field of the earth holds the moon, but you are refering to the magnetic field that the eath generates. Shame on me!