Interstellar Travel - Possibilities and Human Physiology

Interesting questions Sarawak,Here is my take on them: I will answer these three in my explanation below:I assume you are asking if interstellar travel will ever be possible for the human race. If that is the case I would have to say a resounding yes, based on past human progress and technological innovation.The real question is not if but how. There are several ways we can approach this problem. One is that if we use current technology the only way to get to the stars is by using a generational ark due to the long duration of the trek.The fastest interstellar spacecraft in our current arsenal is Voyager 1 which is travelling at 38,600 miles per hour away from the solar system. This is a mere 0.0058% of the speed of light and would require approximately 639,643,679 years to get to even the nearest star of Proxima Centauri at 4.2 light years (24,690,246,000,000 miles) away. Even using a generational ark it is unlikely that a human society living in such close confinement and under such extreme psychological and physical stress as this would survive. Additionally, this independent human society would be more limited in its resources than that of human society on Earth and in the hundreds of thousands of years it would take to travel to this nearest star; it is more likely this slow-moving ark would be surpassed by possibly speed-of-light vehicles created by the much more accelerated and advanced Earth-based civilization. So I chalk this scenario up to being highly unlikely until we can increase the speed of a spacecraft significantly. The only hypothetical vessel that I could see doing this is one which uses interstellar matter/energy (and possibly a supply of matter/antimatter) to supply a continuous "burn" or acceleration throughout its trip. Problem is that it would also require a deceleration to keep it from overshooting its destination. Also, the more massive the vessel (and this space ark would have to be massive to provide a self contained atmosphere/ecosystem for a whole human society) the more energy would be required to accelerate and decelerate it. Just food for thought.If we could increase the speed 100-1000 fold maybe through the use of slingshoting ourselves around the Sun/Jupiter several times in a row (though the g-forces alone would probably kill any large organisms including humans), this would reduce this effect but truly until we can get to near light speed travel i.e. 80-99% the speed of light, interstellar travel to even the nearest stars would be an excruciatingly slow process.I think the real answer to this paradox lies in bending spacetime itself rather than traveling "through" space. If we can bend spacetime itself and create wormholes to other portions of the galaxy and universe the enormous distances between them would evaporate. However, the energy (dark or otherwise) required for this venture would be enormous and much beyond our current technology much less our understanding. However, I think that the answers to the question of interstellar space flight might found through research into the infinitively small realm of quantum physics than just with the study of the macroscopic world of cosmology and astrophysics (though they are all intricately linked together as a whole). Again I believe it is not a question of if interstellar space flight is plausible but rather when will it occur in human evolution. The question depends on whether we are going to a world with or without preexisting life. If the latter, than we should bring with us the minimal necessary life to produce a stable and self-sustaining ecosystem i.e. plants, bacteria, animals, etc. If the former, than I would suggest bringing absolutely zero life (except ourselves) onto the planet, so as not to risk causing an ecological disaster to the world with this already pre-existing life. Even then, our very presence (and all the organisms i.e. bacteria, etc in and on our bodies) could jeopardize and possible exterminatethe pre-existing life on this planet. I would vote for going to a hospitable planet with no life on it to avoid this possible catastrophe to a preexisting ecosystem. The question is how can we achieve speeds of 0.5c? Either way I think a self-contained ecosystem on a space vessel would be required and until human life spans can be substantially extended that generational ark type vessels may be required until we can find a way to bend spacetime itself, thus eliminating this problem completely (though opening up other space and time paradox in its wake).Just my thoughts.Edited by DevilsAdvocate, : No reason given.Edited by DevilsAdvocate, : No reason given.

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For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan

Hmm, I am trying to imagine how we can use the slingshot method for deceleration without in the process further accelerating the velocity of this spacecraft and slinging it further into interstellar space. Can you explain this idea in further detail? I too believe that life in the universe is more prevelant than most people think. However, I think that sencient, self-aware life on the par of humans is very rare, just based on the track record of life on earth.Therefore I suppose the question really should be: Are we willing to sacrifice microbial life or even more intelligent life forms on other worlds which are favorable to humans for the sake of colonization?

This is conceptually plausable according to the laws of physics I suppose. However, the problem I see with this is more of an issue with human intolerance to high g-forces. How can we go from near c speeds (or even 0.5 c) to 0 without creating insanely high g-forces? I would imagine that even to get captured by a solar system's gravity and be swung aroung to reduce it's velocity (like a comet captured by the sun) would still entail high g-force. Any one have a solution to this problem?

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For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan

I would have to agree that robotic interstellar missions are more likely to occur than human treks to begin with due to the high g forces and other life support related issues required for manned missions.

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For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan

Hey Straggler,Good to hear from you again.Interesting concept, though I think much of humanity would be very wary about this proposition. How would we not know that this new extrasolar human civilization not turn around and attempt to anniahalate us on the mother planet, Earth. I guess if we erased all traces of where the robot mission came from it might delay the inevitable meeting between these two human colonized planetary systems but may have dire ramifications for future contact.This sounds like a new pamspermia theory . Would make a great sci-fi story though!

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For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan

Thanks for asking.I am doing well and will be transferring back to a ship (specifically a precommissioned ship) here in about a week. I also just found out that I was selected for Chief Warrant Officer and will be moving on to bigger and better things. Once I am commissioned next year, I will be a pretty busy puppy and you will see less of me here for a couple of years. However, I will try to add the little knowledge I have to further the scientific cause on EvC whenever I can. Good question. I think our understanding of humanity is tied up with our relation with the life on this planet as well as the environmental conditions that Earth entails. If humans evolved on a different planet, with different conditions, and a different global ecosystem, I think we would indeed be different both culturally and psychologically. Just my thoughts.I think a strain of humanity having evolved according to your scenario would probably have a different sense of ethics (we can't even agree to a common moral code here on the earth between cultures and nation states). Is he? That would be great to get his take on this.Off to bed, have a good night all!Edited by DevilsAdvocate, : No reason given.

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For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan

Hmm, I have to agree with Kuresu, proceeding at or near light speed to decelerate to orbit a star system would require the gravity well of a black hole or a neutron/quark star.The reason is this, EM energy only bends around stellar gravity wells and only black holes can actually trap matter/energy proceeding at this speed. Therefore when a near light speed ship approaches a star system it would only hyperbolically bend around it (the amount of bending would be a result of how big the gravity well of the star is) to a slightly different course but could not trap it. Something else would have to be used to tap off its near light velocity to a lower velocity before it could be trapped by the gravity of a stellar system. Edited by DevilsAdvocate, : No reason given.

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For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan

True, the g-loads will be less but even at extreme g-pressures, water has a limit to how much it can be compressed and would result in pressures amounting to a brick wall. The only other way I can see around this is some type of stasis field holding a human body (perhaps in hibernation) which would allow for a cushioning affect of these high g-forces.Just my thoughts.

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For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan

Problem is, I believe that string theorists predict these other dimensions (outside the four dimensions of spacetime) like you said have been reduced in size tremendously during the big bang, in fact reduced in size to planks lengh aka the size of a string. Therefore, I don't think we would be able to travel in these dimensions without drastically changing our physical properties to suite i.e. turn humans (or any thing else we send to travel through these other dimensions) into pure energy. The other issue is the amount of energy required to do this would be on a cosmic scale even exceeding the energy of our sun.So in actuallity this proposal is as prone to failure if not more so than attempting to explore and colonize extrasolar systems imho. That doesn't mean we shouldn't try thought. Just being Devil's Advocate, no pun intended

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For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan