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Lekgolo555

is interstellar or intergalactic travel at all possible

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What does moving at .5C have to do with it? And how can NASA drop an idea for an interstellar craft it's never had plans to make?

 

a few months ago, NASA put out a report (think i saw at space.com) which said they had pretty much given up on your spinning thing. they requested ideas on artificial gravity, but think more for local projects. they did mention this spin idea for a section of a craft, to being practical or a form of an exercise room.

 

if you can picture a large craft moving at 90k mps, in constant rotation from a counter weight, then fine, to you its possible.

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What does "pretty much given up on the spinning thing" mean? They don't have any plans to make such a craft? So what? The farthest they're planning for is the first missions to Mars.

 

And again, what does the velocity relative to Earth have to do with anything?

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It would also be made of ????...hitting a speck of dust at half of the speed of light would release more energy than all the nuclear weapons on Earth.

This is kinda interesting:

http://news.bbc.co.uk/1/hi/sci/tech/6567709.stm

 

Conceivably a powerful enough field would be able to deflect particles before the craft collided with them (rather than just "slowing" the exposure, as with the system described in the article).

 

What would be super handy is if you could produce this field as a cheap by-product of your drive system.

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i believe light speed will be possible one day. Whether we develop it ourselves or it is given to us , i do not know.

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The amount of energy needed to move a spacecraft of any reasonable size to half of c would be multiples the amount of energy mankind has ever used to date. Then it would take an equal amount of energy to slow it down again.

 

There are ways around this, magnetic sails, fusion power sources, in 500 years generating such power will be easy, look at how far we have come in the last 500 years.

 

 

It would also be made of ????...hitting a speck of dust at half of the speed of light would release more energy than all the nuclear weapons on Earth.

 

This is simply not true. .5 c is not fast enough to make a dust particle equal to all the nuclear weapons on earth. Hitting a dust particle wouldn't be a good thing but it is possible to detect such particles and vaporise them far ahead of the space craft with lasers. If we can do that now I am sure 500 years from now we can do better.

 

 

One day we may hope for a 20th or so the speed of light. There is nothing, however, in material engineering to date that would allow stable performance of matter at such a speed without imminent doom.

 

What are you talking about? matter acts the same at .2 c as it does at .000002c

 

It's no just a matter of saying we could do a tenth of the speed of light one day and that would be 50 years to the nearest star. The acceleration would take multiples times that to get to the top speed and the slowing an equal long process.

 

Please elaborate, what do you mean? 50 years to the nearest star is reasonable, if you had a generational type ship even longer would be good. Eventually we'll do away with the need for planets altogether and stars will just be places to get resources not planets.

 

 

We're also assuming there is some reason to go to the nearest dozen stars.

 

Yes there is, to use the resources there to build new artificial worlds and to launch new space craft to other stars to spread humanity out through the galaxy.

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Present day humans are creatures of limits imposed on us by nature. The one,s that may be able to travel to other stars will be quite different. That race may not have enough time to evolve before the present one is eradicated by some cosmic phenomenon.

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Is it possible at all to travel to other planets and star system in a convenient time span?

 

I feelings are that civilization has to colonize other planets in order to survive. We are already past the carrying capacity of earth, and it does not look like we a slowing down.

 

Without faster than light travel we are doomed :eek: :eek: :eek: :eek: :eek:

 

if what we want to do is reduce or stabilize the population on earth would it not the best solution just be to improve the living quality for the people on it since it is at troubled places like Africa and India where the population expands

Edited by kevint0

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Hi,

 

As a sci-fi writer I find this thread very interesting... thought I might add a little spice.

 

My current story has an alien species 10 billion years old working their way across the universe (yes universe) performing a chore which I won't get into. Yes it is a little bit of a jump. How do they do this... ?

 

Recently, to add insanity to craziness, I'd decided I did not want to 'fly around' the speed of light in this book... violation of casualty is what I personally can't get around (though I will have to in future stories).

 

What to do? Well, first the traveler does not age. Second they have machines that can run for billions of years (nanotech) and hibernation chambers which can let them sleep for millions of years. Next, this species knows everything and can juggle black holes between branes... this is their power source for a ship the size of a moon. Their black hole ships travel so close to the speed of light that you might as well say the speed of light.

 

This would do it if it were not for the expansion of the universe. To get around this I'm looking at microscopic worm holes and nanotech. Enough Nanites funnel through worm holes between super clusters to find resources and build another ship... and the aliens which are all nanotech now anyway.

 

Rusty

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To quote Jean-Luc Picard, "anything is possible". I always though the implicit idea was that "however, some things are improbable".

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To quote Jean-Luc Picard, "anything is possible". I always though the implicit idea was that "however, some things are improbable".

 

REPLY: Because of the whole TECHNOLOGICAL SINGULARITY issue and the very real possibility of immortal self improving,self modifying,self replicating AI robots possible outcome I see no reason intergalactic travel would not be possible for such godlike entities. ...Dr.Syntax

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REPLY: Because of the whole TECHNOLOGICAL SINGULARITY issue and the very real possibility of immortal self improving,self modifying,self replicating AI robots possible outcome I see no reason intergalactic travel would not be possible for such godlike entities. ...Dr.Syntax

dr.syntax, you need to stop mixing threads and subjects. This has nothing to do with the supposed singularity, which has a thread on its own. Stay on topic, please, and keep each thread's topic on its own thread.

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dr.syntax, you need to stop mixing threads and subjects. This has nothing to do with the supposed singularity, which has a thread on its own. Stay on topic, please, and keep each thread's topic on its own thread.

 

You didn't use your special moderator text. :doh:

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Speaking of interstellar travel, there is an article out there that claims that it may be possible develop the ability to manufacture sufficient amounts of antimatter in a couple of decades: http://www.engr.psu.edu/antimatter/Papers/NASA_anti.pdf

 

There is not too much math in it, other than basic algebra and simple formulas. And a couple of graphs. So, if you want to read it, then go ahead and enjoy. One thing I found interesting is that antimatter production does seem to be expanding exponentially, so who knows, maybe late in the 21st century we might be able to build a relativistic space-craft.

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The expansion of the universe does not preclude intergalactic travel, though it does limit the range. An additional limit is that the longer they wait, the less galaxies they can travel to. As the universe expands, some galaxies will leave the "local universe" by which I mean the portion of the universe that can interact with a particular location. I'm pretty sure that it is possible for a species to travel to every star that will eventually be in the local universe seen from its homeworld. Ie, even if they could reach farther stars, they would be forever unable to report back to or interact with their homeworld because of the expansion of space. Would that be good enough?

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Well, I'm actually a bit skeptical about intergalactic travel, simply because of the enormous distance between galaxies (the Andromeda galaxy, one of the closest galaxies to us, is more than 2 million light years away).

 

Even if we just send unmanned probes or even Von-Neumann probes, I doubt they would remain functional for very long.

 

To put it in perspective, we've already built probes that can last for decades. We could probably make space-craft that can remain functional for hundreds of years. It's pretty unlikely that we could design anything that can last more that a few thousand years (although it is not strictly impossible I suppose). But millions of years at sublight speeds? Forget it. Most human made things and structures don't even make it to 1000 years, let alone hundreds of thousands to millions of years...

 

No, I think if we do find any sort of extraterrestrial intelligence, it will most likely have originated from this galaxy.

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Well, I'm actually a bit skeptical about intergalactic travel, simply because of the enormous distance between galaxies (the Andromeda galaxy, one of the closest galaxies to us, is more than 2 million light years away).

 

Even if we just send unmanned probes or even Von-Neumann probes, I doubt they would remain functional for very long.

 

To put it in perspective, we've already built probes that can last for decades. We could probably make space-craft that can remain functional for hundreds of years. It's pretty unlikely that we could design anything that can last more that a few thousand years (although it is not strictly impossible I suppose). But millions of years at sublight speeds? Forget it. Most human made things and structures don't even make it to 1000 years, let alone hundreds of thousands to millions of years...

But you are forgetting Relativity. If we can accelerate a probe to near light speed, then to it, the journey between galaxies would not take millions of years, but could in fact take only a few years. If we could just give it 1g of thrust (9.8m/s/s) the time dilation of the journey would put it in the range of reliability we can do today.

 

For us it would seem like millions of years, but to the probe, it might only seem decades.

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If an efficient enough energy source were discovered, that allowed a ship to keep 1g acceleration could time dilation allow for humans to make the same journey?

 

How fast do you need to travel for time dilation to take effect?

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If an efficient enough energy source were discovered, that allowed a ship to keep 1g acceleration could time dilation allow for humans to make the same journey?

 

How fast do you need to travel for time dilation to take effect?

 

Time dilation takes effect at any speed, it is just that it takes high speed for it to become significant.

 

For instance:

 

At 30 km/sec (.01% of c) the dilation factor is 1.00000005

 

at 1% of c it is 1.00005

 

10%c = 1.005

 

50%c = 1.15

 

75% = 1.5

 

90% = 2.29

 

99% = 7

 

99.9% = 22

 

99.99% = 71

 

etc.

 

So if you were trying to get to Andromeda, accelerating a 1g halfway there and then decelerating the rest of the trip , it would take about 19 yrs, for you, and you would reach a top speed of 99.9999995655% of c.

 

The trick is finding a propulsion system that allows you to reach those speeds while using a reasonable amount of fuel.

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Janus,

 

What are these numbers?

i.e.

10%c = 1.005

 

What is 1.005? Say I'm traveling for 10 years at 10%c, how do I use 1.005 to calculate subjective time.

 

May I ask yefow did you come by these numbers?

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Have you ever read The Dark Beyond the Stars? It's about a generation ship. built to house a human colonly for thousands of years. Sure it is SF but it is the most realistic approach we are capable at the moment.

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There are a number of techniques for FTL travel which are scientifically plausible but not yet technically possible.

 

The Alcubierre 'warp' drive is well within the bounds of physics: To achieve this we would need awesome amounts of energy to warp space so that in front of a ship the space is compressed and behind the ship the space is expanded. Then moving locally at sub-relatavistic speeds, the ship would appear to an external observer to be moving faster than light. It may be possible to achieve this energy with a matter/anti-matter reaction and the large electron-positron collider at CERN has already produced small amounts of antimatter. Projects are currently underway to find mass-production methods.

 

The wormhole idea as already mentioned is plausible. Most senarios that allow traversable wormholes insist that the wormhole will close if any matter comes into contact with it and so yes, exotic particles with negative energy are required to hold it open. Negative energy can be produced by moving 2 matal plates infinitessimally close together to the point where particle pairs can no longer appear between them. At this point the energy in the space between the plates becomes less than the vacuum energy hence negative. (I think that's how it works anyway, feel free to correct me on the details of that) So if a shell of this composite material could be placed around traversable wormhole then it becomes stable.

 

The problem with wormholes is that they connect across space AND time. Since time is relative, hence passing at different rates in different places, it is unlikely that both ends of the wormhole would be experiencing the same passage of time and so a hypothetical colony on one end would be in a different time to the other end. You may find yourself arriving at your destination before you left.

 

The other possibility is hyperspace. It's a word that's thrown around a lot in sci-fi without any real explanation of what it means. Essentially there are another (probably 6) dimentions in addition to our conventional 4 dimensional space-time. At the big bang, as our 4 dimensions expanded into the known universe, the other dimensions contracted and are now curled up at the plank length, which is something like a billionth the width of a proton. If we could access these other dimensions and travel through them emerging again at our intended destination, the actual distance travelled would be miniscule.

 

This is all of course, highly theoretical at the moment.

 

I recommend Michio Kaku's book, "Physics of the Impossible" It explains the possible science behind a lot of pure sci-fi ideas.

 

In the mean time, I'm in favour of generation ships. Load 10,000 people onto a giant ship and their decendents will arrive to colonise another star system. I'd volunteer in a second!

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The Alcubierre 'warp' drive is well within the bounds of physics: To achieve this we would need awesome amounts of energy to warp space so that in front of a ship the space is compressed and behind the ship the space is expanded. Then moving locally at sub-relatavistic speeds, the ship would appear to an external observer to be moving faster than light. It may be possible to achieve this energy with a matter/anti-matter reaction and the large electron-positron collider at CERN has already produced small amounts of antimatter. Projects are currently underway to find mass-production methods.

 

 

Unfortunately, a recent paper has thrown a wet blanket on the Alcubierre warp. It is purely a classical theory which does not take into account quantum mechanics. It turns out that when you add QM into the picture, the warp in not stable and even if you could maintain it, everyone in a craft propelled by it would be fried by Hawking radiation.

 

The wormhole idea as already mentioned is plausible. Most senarios that allow traversable wormholes insist that the wormhole will close if any matter comes into contact with it and so yes, exotic particles with negative energy are required to hold it open. Negative energy can be produced by moving 2 matal plates infinitessimally close together to the point where particle pairs can no longer appear between them. At this point the energy in the space between the plates becomes less than the vacuum energy hence negative. (I think that's how it works anyway, feel free to correct me on the details of that) So if a shell of this composite material could be placed around traversable wormhole then it becomes stable.

 

There is no way for us to presently create the exotic matter needed even in theory. There isn't any evidence that it is even possible for such exotic matter to exist.

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