How far can we go?

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How far can we go?

Postby alpha_3 on February 22nd, 2010, 6:21 am 

We often speak about travelling into space. But how far can we go? Are there speed limits and which are the most optimistic scenarios? The stars, beside our sun, or another galaxy? Are we condemned to live in our astral neighbourhood for ever?
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Re: How far can we go?

Postby Lincoln on February 22nd, 2010, 2:16 pm 

Realistically?

Solar system only.
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Re: How far can we go?

Postby BioWizard on February 22nd, 2010, 2:18 pm 

How about theoretically? Anything that's not accelerating away from us, or more specifically, anything that won't be moving away from us at the speed of light before we manage to reach it?
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Re: How far can we go?

Postby Lincoln on February 22nd, 2010, 2:27 pm 

That's a generous usage of "theoretically." Of course, it's true, at least sort of. But once you get there, it won't be moving very fast....after all, most of the motion is expansion of space between here and there. Once you're there, you're traveling along with space.
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Re: How far can we go?

Postby alpha_3 on February 22nd, 2010, 5:18 pm 

I dont't know if we must take the following scenario seriously, but it is not -apparently- science fiction. It's Pr. Hawking who writes that in his web site: http://hawking.org.uk/index.php?option=com_content&view=article&id=65


"There is no time, to wait for Darwinian evolution, to make us more intelligent, and better natured. But we are now entering a new phase, of what might be called, self designed evolution, in which we will be able to change and improve our DNA. There is a project now on, to map the entire sequence of human DNA. It will cost a few billion dollars, but that is chicken feed, for a project of this importance. Once we have read the book of life, we will start writing in corrections. At first, these changes will be confined to the repair of genetic defects, like cystic fibrosis, and muscular dystrophy. These are controlled by single genes, and so are fairly easy to identify, and correct. Other qualities, such as intelligence, are probably controlled by a large number of genes. It will be much more difficult to find them, and work out the relations between them. Nevertheless, I am sure that during the next century, people will discover how to modify both intelligence, and instincts like aggression.

Laws will be passed, against genetic engineering with humans. But some people won't be able to resist the temptation, to improve human characteristics, such as size of memory, resistance to disease, and length of life. Once such super humans appear, there are going to be major political problems, with the unimproved humans, who won't be able to compete. Presumably, they will die out, or become unimportant. Instead, there will be a race of self-designing beings, who are improving themselves at an ever-increasing rate.

If this race manages to redesign itself, to reduce or eliminate the risk of self-destruction, it will probably spread out, and colonise other planets and stars. However, long distance space travel, will be difficult for chemically based life forms, like DNA. The natural lifetime for such beings is short, compared to the travel time. According to the theory of relativity, nothing can travel faster than light. So the round trip to the nearest star would take at least 8 years, and to the centre of the galaxy, about a hundred thousand years. In science fiction, they overcome this difficulty, by space warps, or travel through extra dimensions. But I don't think these will ever be possible, no matter how intelligent life becomes. In the theory of relativity, if one can travel faster than light, one can also travel back in time. This would lead to problems with people going back, and changing the past. One would also expect to have seen large numbers of tourists from the future, curious to look at our quaint, old-fashioned ways.

It might be possible to use genetic engineering, to make DNA based life survive indefinitely, or at least for a hundred thousand years. But an easier way, which is almost within our capabilities already, would be to send machines. These could be designed to last long enough for interstellar travel. When they arrived at a new star, they could land on a suitable planet, and mine material to produce more machines, which could be sent on to yet more stars. These machines would be a new form of life, based on mechanical and electronic components, rather than macromolecules. They could eventually replace DNA based life, just as DNA may have replaced an earlier form of life.

This mechanical life could also be self-designing. Thus it seems that the external transmission period of evolution, will have been just a very short interlude, between the Darwinian phase, and a biological, or mechanical, self design phase. "
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Re: How far can we go?

Postby BioWizard on February 22nd, 2010, 5:35 pm 

alpha, answering a lot of these questions requires more than simple introductory explanations. You should consider asking them in the more advanced forums, or breaking them into individual questions to be answered separately. Otherwise, this discussion is going to go over the level of this forum pretty quickly.
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Re: How far can we go?

Postby Lincoln on February 22nd, 2010, 6:00 pm 

alpha....

You said "we", which I took to mean life. A mechanical probe to another star is possible. Expensive and perhaps silly, but possible.

On a time scale of 10-15 years, we will be imaging "Earth-ish" planets using space-based observation platforms. The Kepler probe is doing that right now.

Regardless, even sending a probe to the nearest system will take very, very long times. One can do a simple calculation. The New Horizons spacecraft will take 9 years to get to Pluto. Pluto's orbit has a mean radius of about 6 billion km. Alpha Centauri is 4 lightyears away. That's 4 x 1013 km. Ignoring anything other than orders of magnitude, that's 10,000 times farther away. So we're talking about 100,000 years transit time.

Yes, yes, we could do better if it was crucial. But that's the closest star and not necessarily one with life or a planet suitable for humanity.

Bottom line is that it'll be hard. Sending humans will be unimaginably harder.
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Re: How far can we go?

Postby alpha_3 on February 22nd, 2010, 6:29 pm 

I find, too, the scenarion described by Hawking at least horrible. But there were so many things in there!: supermen, mechanical evolution, space colonization etc.

So, the solar system is our actual and biological limit. I take all the rest as fiction.
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Re: How far can we go?

Postby Lincoln on February 22nd, 2010, 7:35 pm 

Actually, I would argue that the Earth is the realistic biological limit. Yeah, we can go other places, but at enormous cost and no viable possibility of self-sustainability. Maybe we can find a place with adequate water where one can grow food. But even Biosphere 2 here on Earth needs periodic external maintenance.

This reality has no power to fire men's souls, but it might help convince us to treat the Earth a bit more intelligently. It's a bit hippy, but it's also a lot true.
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Re: How far can we go?

Postby BioWizard on February 22nd, 2010, 7:47 pm 

Lincoln wrote:Actually, I would argue that the Earth is the realistic biological limit. Yeah, we can go other places, but at enormous cost and no viable possibility of self-sustainability. Maybe we can find a place with adequate water where one can grow food. But even Biosphere 2 here on Earth needs periodic external maintenance.

This reality has no power to fire men's souls, but it might help convince us to treat the Earth a bit more intelligently. It's a bit hippy, but it's also a lot true.


Amen my hippy brotha.
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Re: How far can we go?

Postby Natural ChemE on February 22nd, 2010, 8:42 pm 

You? You'll go lots of light years, alpha. Sure, the Earth and other parts of the solar system are going to tend to go in the same general direction, but you'll be moving! Well, depending on where you perceive as being stationary. Kind of an arbitrary consideration in ways.

About the living-off-Earth thing, though? Yeah, it would surprise me if living off in space wasn't viable in a century or two. I'm pretty sure that humanity will have to have go through a near-extinction event or prolonged dark age for us to not have people living comfortably out in space in a thousand years.

With our current breed of technology, we're going to be star-bound. With our current level of physical understanding, we will be unable to travel between stars practically. While that very well may change, travelling between stars is not something not practically viable.

If we are successful in creating a strong AI (synthetic intelligence of human-like quality) of electronic nature, such an entity should find it relatively easy to transverse our solar system and galaxy. Such entities, should they be created in the near future, may well become a more universal life form while humans stay back at home. Of course, despite my optimism, it is debatable whether or not a strong AI will be in the near future for us.

Less controversially, though, it's fairly well established that:
a. solar cells are an increasingly cheap and effective technology;
b. solar cells produce electricity when exposed to sun light;
c. there's a lot of sun light near the sun;
d. we can do a lot of major things with electricity;
e. a lot of these things that we can do with electricity can be used to establish a living environment;
f. we're getting better at using electricity by leaps and bounds just about every year now.

I’m fairly sure that, given the time and resources, I could personally design a viable, sustainable space station. It would utterly shock me if a team of brilliant engineers with technology advanced by 100-years couldn’t do better.
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Re: How far can we go?

Postby CanadysPeak on February 22nd, 2010, 8:50 pm 

There may be some new technology just around the corner, but for now, we're going to be confined to our solar system and quite possibly the near one at that. The two biggest obstacles are fuel (you have to carry it with you; a solar sail might be possible (well, I like the idea even if it's not practical!) but it wouldn't transport much mass I think). The biggest problem at the moment is that you kill people if you put them into a two year trip. Their bones fall apart, they lose all muscle tone, etc. We're made for gravity. You could probably come up with some type of artificial gravity, but it seems like it would be huge and heavy and require a lot of fuel.
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Re: How far can we go?

Postby alpha_3 on February 23rd, 2010, 9:31 am 

I propose we discuss the whole thing with more detail. Bio, should we change forum, or stay here and see how it evolves ?
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Re: How far can we go?

Postby BioWizard on February 23rd, 2010, 9:46 am 

Yep, I suggest you switch forums.
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Re: How far can we go?

Postby Lincoln on February 23rd, 2010, 10:51 am 

Natural...

Living off Earth isn't the question. It's distance from Earth. Plus the OP asked about "we" not "some AI thingy."

Back to the OP...

This is actually pretty easy to calculate. Come up with a list of the things you need to survive for your life. So that means dirt for food, air + recycling, water and so on. In order to be anything other than a pointless exercise, you need a breeding population with adequate diversity, etc. Just for the hell of it, you could just calculate the mass of the international space station, add a factor of ten or a hundred or whatever for the stuff that isn't there. Then calculate how fast you need it to go to get wherever you want to go in a sensible time. The nearest star is four light years away. Travelling at a tenth the speed of light doesn't invoke a lot of relativity and that means a 40-ish year transit.

Calculate how much energy it requires to move that many tons to near even a ridiculously fast tenth of the speed of light. That's a tremendous amount of energy. And if you're going to do it the only way we really know how (throwing mass out the back of the space ship), you can work out the hottest temperatures we can make now...then add a factor of ten for improvements...and this leads you to figure out how much reaction mass you need to bring along, which increases the amount of mass you need to start with.

Blah, blah, blah. In the end we find out that it's the engineering that kills you. Engineers are clever lads and lasses, but we're talking huge improvement factors in things that don't grow quickly. It's not like computer chips that improve every year. If it did, we'd have rockets that make the Saturn V look like a firecracker and we haven't matched the Saturn V for 40-ish years. And that was to lob a miniscule package to the moon.

The bottom line is that if there were a reason for the Earth to band together, we could come up with something that left the solar system with a large payload. But it will be slow, smaller than we'd like, etc.

Without some radically new technology, unimaginable by our current standards, we're stuck here. Maybe some unmanned probes that will report back in hundreds of years might be possible. But that's about it.

Personally, I'm waiting for Mr. Spock and ET to come and show me how they did it....
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Re: How far can we go?

Postby Charles miller on April 13th, 2011, 2:59 am 

The space habitat idea is not irrelivant to "how far we can go". Once we have a viable space habitat we just need to set it on a course to another star system and eventually it will get there. The trip will take several generations but so what?
I am visualizing a space habitate with a significant population. At least comparible to a moderate size city or a small country, say 200,000 to a million persons. The citizens would just be going about the business of daily living in an environment that is not just able to endure space but designed to thrive in it without any need for planet based support.

Once we have space habitats that are comfortable existing out in the ort cloud, it is just a matter of time before some of them are in the ort clouds of neighboring stars. Of course by that time humanity will have no need for, and little interest in, finding earth like planets.
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Re: How far can we go?

Postby dragslaye on June 28th, 2011, 3:40 pm 

Charles by no means I am an engineer, but as an Architect I can tell you that to make a building to host 200 000 on earth is very hard, now you are proposing to build a city which is able to travel through space while be able to support life.... such an enterprise wouldn't be possible with our current means. To start with you will have to be able to build your craft on space, so you have to take into account how much fuel will you need to fly off the material needed. Next you need people to build (on Earth) and assemble (on space) the parts of spacecraft.
Taking into account that in order to build a big construction such as a high rise (which in average can take up to 5 years to build) you need teams compose of hundreds of people, you will need to be able to host a big number of people with enough technical knowledge and space training in outer space in order to build your spacecraft. After that you will need enough energy to move your spacecraft without taking into account the energy need to keep the life support systems working. I am yet to take into account that our bodies are no suitable for space (the absent of gravity can really affect the human body)
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Re: How far can we go?

Postby Mendicant Bias on June 29th, 2011, 8:03 am 

I think as far as our technology can go now and for the forseeable future, we are pretty much stuck in our solar system until (probably in a few hundred years) we discover a breakthrough in physics and can alter forces such as gravity.

Either that, or as Lincoln said, we wait for ET to find us and tell us how they did it.
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Re: How far can we go?

Postby moranity on June 29th, 2011, 8:48 am 

so, for a start, if we dont get life off this planet, we doom all life to destruction, that is fact, maybe in 4 billion years, but still its waiting for sure.
what we need is the ability for small groups to be self sufficient in space, to do this you need energy and resources and the technology to protect humans and sustain them. Self sufficient groups can travel from resource to resource and will, with in a couple of million years, even travelling at 20,000 km an hour, colonise all the galaxy, all we need is patience and the ability to be self sufficient in space.
we do not need to grow food, engeneered bacteria could produce all we need from simple organic materials harvested from asteroids, for example, or from gas clouds, not fun, but there will be a time when all we can hope for is the survival of life.
all the dangers in space are also energy sources, a magnetic field used to deflect and harvest high energy particles, for example.
we do not want huge structures, we need small self sufficient groups, else we will repeat all the power structures we now have.
As for the gravity problem, there are solutions, but i bet alot of old people would benefit from the lack of gravity
edit to add:
the point is we dont need to go fast, we need to go and be self sufficient
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