# Will humans ever leave the solar system?



## cchurchi (Feb 1, 2007)

I believe most (if not all) people are unable to even begin to comprehend the nearly infinite distances involved with interstellar travel. I asked a few co-workers of mine if they thought human interstellar travel was possible and they all thought that it would only be a matter of time before some future variation of a star trek style warp drive or man made worm hole would be invented allowing humanity to begin to spread out among the stars.

Well, either of these very unlikely possibilities would require a new theory to replace Einsteins theory of relativity and would also mean that the speed of light would no longer be the ultimate speed limit. 

Although worm holes may be possible, the mathematics that describe them also predict they would be incredibly tiny, small enough that only a single subatomic particle could enter one; an event that would completely destablilize it. As far a building a worm hole, the energies required may make constructing one completely unattainable.

So unless the universe is very different from the relativistic one Einstein describes we are left calculating how much energy is required to accelerate a given amount of mass (as well as accelerate that mass in the opposite direction to slow it down when reaching the selected destination) in a time frame that hopefully dosen't take many thousnds of years, (seeing as how impatiant us humans are, I can hear it now - "are we there yet?")

When looking at these numbers, it soon becomes obvious that the energy required to send even a very small ship with only a few passengers to the nearest star, Proxima Centauri, which is "only" 4.5 light years away, is greater then the sum of all of the energy generated by humanity throughout all of human history! 

Besides the the challenge of storing that much energy safely, there are other issues that arise when approaching even a few percentage points of the speed of light. At such speeds, even the tiniest spec of dust will detonate on the windshield of your space craft with the force of an atom bomb. Also, the closer your ship gets to the speed of light, the more it's own mass increases, requiring ever more energy to accelerate it, until at the speed of light it's mass becomes infinite.

For these reasons, I believe that humans will never leave the solar system. We may one day completely populate our own solar system and may send un-manned probes to other stars and systems, but the time, radiation, distance, energy, and cost would be too great, if it's even possible at all. If it is possible, they why isn't the galaxy crawling with the first aliens that invented the technology?


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## PhotonBoy (Feb 1, 2007)

I agree. Your posting reminded me of Fermi's Paradox: "So Where Are They?"

http://home.tiac.net/~cri/1998/alien.html


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## Carpenter (Feb 1, 2007)

I would like to think we are someday going to leave our solar system for what is "out there", but since we are only setting our sites on the moon (again or for the first time - you decide), it will take a long time before that happens, if at all.


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## Perfectionist (Feb 1, 2007)

All makes sense ..... but at the same time humans never thought they would fly or reach the moon a thousand years ago !

I believe, given enough time, science and technology will make the impossible possible .....

Zero Point Energy seems a perfect source for space exploration ..... and who knows for sure whether aliens are not crawling the galaxy !!


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## matrixshaman (Feb 1, 2007)

Element 115 - ever seen Bob Lazar (former employee at Area 51) talk about how alien craft get here? Of course that depends on whether you believe him but take a look here: http://www.gravitywarpdrive.com/Element_115.htm
Basically it creates a warp in space that brings a distant point close. Reports of UFO's that suddenly take a sharp turn and then disappear is also thought to be their use of this technology.


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## Casual Flashlight User (Feb 1, 2007)

Element 115

That's a track by a group called "Eat Static". I wondered what it was, now I know.






Um, and I don't see us even colonizing other planets in this solar system...I used to think we'd strike out into the universe, but I don't see any evidence of a serious desire to do it.

Maybe we'll have a half hearted pop at it when we've messed up the planet so much that we can't even breath.






CFU


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## WAVE_PARTICLE (Feb 1, 2007)

Leaving our Solar System is not a question of if, but when. It's inevitable. The thing is, the pace of the whole thing will be much slower than people think. Even to travel to the nearest star, Proxima Centauri, and we were to figure out a way to travel at close to the speed of light (somehow) say maybe half the speed of light, it would take like 10 years to get there.....another 10 years to get back. The whole project would be half a lifetime. And really, there's nothing particularly special near Proxima Centauri.

Want something interesting like Chara A? It is 100 light years away! Traveling at half the speed of light will take 200 Earth years to get there!

so, short answer: yes, we will leave the solar system, but it won't be anything like Star Trek! You can't travel faster than the speed of light. And we can't fold space-time.

It's nice to imagine, though.

:rock: WP


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## matrixshaman (Feb 1, 2007)

This one covers a lot too as well as Lazar's background: http://www.gravitywarpdrive.com/Government_Scientist.htm
Professor Stephen Hawking has been saying lately that if the human race is to survive that we will need to eventually find other places to live than Earth.


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## WAVE_PARTICLE (Feb 1, 2007)

By the time we messed up our planet to the point we need a new one, there just won't be enough time to do the proper exploration and colonization. Something like that would take centuries (refer to my comment above), unless some technological marvel is discovered that allows us to circumvent the limitations of the universe like the speed of light. Not likely to happen.

If we are at the point that we have to ditch the planet, I can picture an all-or-nothing approach in which perhaps 1000 colonization ships are built to house perhaps a million people. These ships fan out to the top-1000 most likely habitable planets closest to Earch with the "Hail-Mary" hopes of finding at least one planet that is livable. And then Mankind is rebuilt.

Not a very pretty picture, but the most likely scenario. So take care of our planet!

WP


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## scott.cr (Feb 1, 2007)

> When looking at these numbers, it soon becomes obvious that the energy required to send even a very small ship with only a few passengers to the nearest star, Proxima Centauri, which is "only" 4.5 light years away, is greater then the sum of all of the energy generated by humanity throughout all of human history!



I saw on a TV special about relativity and space travel that attempting to accelerate a single atom to a relative speed of 1/2 the speed of light would take more than all the energy in the universe!!

So when the E.T. ships make sudden 90-degree turns I guess the question becomes: What is inertia and how can we control it? Isn't inertia the root of the problem (or at least a significant part)?


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## cchurchi (Feb 1, 2007)

We need JS to post his opinion on this. In the mean time I found this:


Time, fuel, and distance are some of the problems we run into when considering interstellar travel. For example, if we were to build a rocket that would get us to Proxima Centauri, the nearest star besides the Sun, in less than 900 years, we'd need more fuel than there is mass in the universe! 1

http://www.nasa.gov/centers/glenn/research/warp/scales.html


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## mchlwise (Feb 1, 2007)

Very interesting points. 

Personally, I don't believe we will ever leave the solar system. As stated, the energy involved makes it certainly impractical, probably impossible. 

I don't buy the "science will get us around it someday" or the "100 years ago people said ____ was impossible" arguments either. Certainly, we haven't learned all there is to know, and there's lots to discover and understand that we don't now. However, what we DO know and understand now is thousands of times greater than what was known and understood 100 years ago, and therefore we are much better able to make educated predictions about what will or won't be possible, no matter how much science advances. 

All of this naturally leads to the E.T. arguments and questions, and leads me to believe that not only will we not leave, but nobody has come. I know a lot of people have seen things, and I don't know what they saw, but neither do they. Whatever it was, I'm betting it wasn't beings from another galaxy. 

:candle:


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## Diesel_Bomber (Feb 1, 2007)

Interesting reading, I look forward to following this thread.

:buddies:


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## cchurchi (Feb 1, 2007)

So until Newton and Einstein are disproven it is quite apparent that interstelar travel is impossible. Unfortunately, every relativity experiment to date confirms Einsteins theories.


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## WAVE_PARTICLE (Feb 1, 2007)

cchurchi said:


> So until Newton and Einstein are disproven it is quite apparent that interstelar travel is impossible. Unfortunately, every relativity experiment to date confirms Einsteins theories.


 

We don't have to "disprove". We just need to "bypass".
The best odds is to figure out how to fold space-time......we can call it 4th dimensional travel. I haven't got around to that yet..... :laughing: 


WP


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## Casual Flashlight User (Feb 1, 2007)

> The best odds is to figure out how to fold space-time......we can call it 4th dimensional travel. I haven't got around to that yet.....


 
Let us know when you do...I could do with a change of scenery.






CFU


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## cchurchi (Feb 1, 2007)

Yes, if we could just force 2 supermassive black holes to orbit each other at near the speed of light, we could cause enough frame dragging to...


Oh dang, that is the recipe for time travel.

I will rent DUNE tonight and pay extra attention to the space folding scenes. Then all we will need is some SPICE!!!


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## Casual Flashlight User (Feb 1, 2007)

> Then all we will need is some SPICE!!!


 
The Spice Must Flow.






CFU


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## cchurchi (Feb 1, 2007)

Burning enough spice to travel to Proxima Centauri would release trillions of tons of CO2 causing "universal warming" thereby melting the martian polar ice caps, which will only add to the CO2 problem!


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## greenLED (Feb 1, 2007)

"Eever" can be such a strong word...

I believe we'll eventually leave the solar system, but most probably after doing a bit of "planet hopping" around our own back yard.


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## evan9162 (Feb 1, 2007)

> I saw on a TV special about relativity and space travel that attempting to accelerate a single atom to a relative speed of 1/2 the speed of light would take more than all the energy in the universe!!



Complete bollocks. They are accelerating even heavy particles (gold) to 99.99% the speed of light in particle accelerators. Hardly all the energy in the universe.


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## jtr1962 (Feb 1, 2007)

I feel we will find some means of folding space-time to accomplish this task, assuming the human race survives long enough. Provided you don't actually travel faster than light speed in the space-time continuum you're in there is no violation of known physics. Of course, we don't yet know how to fold space-time.

I think once we're comfortable with fission and fusion powered spacecraft we will at least colonize the solar system. A trip even to Pluto in such a craft could take mere weeks. The thing that surprises me is the slow pace of progress since those first moon landings nearly 40 years ago. We were supposed to have moon bases by the 1970s, Mars landings by the 1980s, colonies on Mars by the 1990s, manned exploration of Jupiter and Saturn by now, etc. Technologically we could have done it. The will just wasn't there. The general public just couldn't see the potential. Just what was spent on war and welfare in the last 40 years would have more than paid for all this. Probably selling the spinoffs would have covered a large part of the cost.

We're probably going to have to venture forth to other solar systems just to survive since man won't voluntarily limit his numbers, and this planet has an ultimately capacity of anywhere from 10 billion to 100 billion humans, depending upon who you ask. So in the end either we go to the stars or we end up on the cosmic trash heap.


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## grapplex (Feb 1, 2007)

...


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## JonSidneyB (Feb 1, 2007)

Ummm,

When they see that the sun is about to end it's hydrogen fusion time and move on to helium fusion then man will take it seriously. The problem is by then man will lost the ability to walk since we will have devices to replace all walking. Humans will be slugs by them with little concept between reality and the 7 billion years from now version of cyberspace. We will no longer be able to recognize them as human anymore.

The last generation on earth will complain that the last did not do anything to prepare but that generation decided it was the last generations problem. The final generation will work on the problem but run out of time and be caught up in the change of the Sun and die out.

Then the solar system will be quiet from life once more.

Then again I could be wrong.


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## grapplex (Feb 1, 2007)

...


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## Oddjob (Feb 1, 2007)

I think that if it can be imagined it can be accomplished...eventually. The vastness of the universe leads me to believe that there is science beyond our science and possibitities beyond our imaginations. There is so much that is still not known in our scope of knowledge. This is probably a daydreamer's point of view but daydreams have served us well so far...


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## EngrPaul (Feb 1, 2007)

No, but Michael Jackson already has.


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## js (Feb 1, 2007)

evan9162 is right!

It doesn't take that much energy to accelerate an ionized atom (even a heavy one) to 99.999 percent the speed of light. Of course, to accelerate it to 100 percent the speed of light would take infinite energy! LOL!

However, even so, accelerators take a LOT of energy to run. I work at Cornell Universities accelerator, known as "CESR" which stands for "Cornell Electron Storage Ring", and we use about $150,000 worth of electricity every month, almost all of it to power the RF cavities which accelerate the beams. You DO have to pay to get things moving at high relative speeds. No doubt.

Here are some numbers:

First of all, many of you might remember the formula for kinetic energy from a physics class: 

KE = 1/2 m v^2. 

This is a non-relativistic formula, but works just fine for a truck going at 60 MPH, weighing 1 ton. That is the same as 26.82 meters/second and 907 kilograms. Using the formula, we get

KE = .5 * 907 kg * 719.3 m^2/s^2 = 326,202 Joules.

OK. Now lets compare that to the energy necessary to accelerate a 1 ounze marble to 90 percent of the speed of light. Unfortunately, the formula for relativistic Kinetic energy is much more difficult to write than its non-relativistic cousin! Here it is:

KE = mc^2 ( 1 / sqrt(1 - v^2/c^2) - 1 ), where m is the rest mass of the object.

Substituting, we get,

KE = mc^2 ( 1 / sqrt(1 - .9^2) -1 )
KE = mc^2 ( 1 / .435 - 1)
KE = mc^2 ( 1.29 )
KE = 1.29 * 0.028 kg * ( 2.998 * 10^8 m/s )^2
KE = 0.037 kg * 8.988 * 10^16 m^2/s^2
KE = 3,326,000,000,000,000 Joules

Or, roughly, 3.3 quadrillion Joules. That's a *one ounze object!*. And that's a LOT of energy, needless to say. But, certainly nothing like more energy than the US has ever produced. In fact, a 1000 MegaWatt reactor would produce this much energy in 38 and a half days. However, consider that that same reactor could accelerate the 1 ton truck to 60 MPH in less than a milisecond! 3 tenths of a milisecond, actually.

Kinda puts things in perspective, doesn't it? LOL!

Tp accelerat the 1 ton truck to .9 c, on the other hand, would require 24,513 times more energy than the marble. That means the same 1000 MW plant would take 2,585 YEARS to accelerate the truck to .9c.

And I don't need to tell you how freaking powerful a 1000 MW reactor is! And the problem is that even if you added that kind of power plant to the 1 ton space ship, *it would also have to accelerate itself!*. A thousand megawatt reactor weight *ahem* quite a bit.

So, fanciful (and fun) thought experiments about sending a ship to the nearest star, are, well, flights of fancy at this point.

Plus, as cchurchi points out, running into a marble sized rock at a relative collision speed of .9c would mean certain destruction. It would be, as they said in Ghost Busters, "BAD". "OK. That's bad. Thanks Igor for the safety tip."

But, there has been one point of confusion here, and that is the lack of consideration of time dilation. If you were on that ship accelerated to .9c relative to Earth, the journey would not seem to you to take 4 years. People on Earth would see you taking 4 years to get to the star 4.5 LY away, but to you, it would be a considerably shorter journey.

And in fact, if you could travell at almost the speed of light, you could get anywhere in the universe in almost none of your own time.

Another point to consider, though, is radiation. Outside of the Earth's protective atmosphere, there is a lot of radiation. And there's no easy way to shield against it. I mean, if you use lead you add lots of mass to your space ship. I seem to remember someone here at work saying that in any practical situation, any trip to mars by a man or woman, there and back, would deliver a fatal dose of accumulated radiation. Not sure if the person knew what he was talking about or not, but I suspect he did. In any case, though, radiation is an issue in some scenarios. Outside the solar system I suspect radiation would be much less, though, but I'm not sure.

Anyway, as for the question of this thread, "Will humans ever leave the solar system?", I'm going to have to give a very solid, very definite answer:

I DON'T KNOW.

Sorry to pass on this question, but y'all can add the positive contributions of this post, taken from what I do know, and maybe be a bit closer to answering it for yourself.


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## js (Feb 1, 2007)

Oddjob,

Elisha Cuthbert, eh? Nice avatar! Zowie.


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## elgarak (Feb 1, 2007)

Don't forget about time dilation. The travel appears shorter for the traveler than for observers staying in one place.

Read Arthur C Clarke's Rama series. In it, some humans do several interstellar travels within their lifetime into the near neighborhood (~15 ly). IIRC, the Rama spacecraft travels at rather moderately 60% c. Granted, it's an alien craft, and there's no conceivable way to engineer a craft traveling that fast (_yet!_), but I just wanted to point out that the upper limit of c does NOT preclude interstellar travel. 

Clarke did major in math and physics and at some time worked as a radar engineer (during WWII) and theoretical astrophysicist (after the war). He wrote a paper on the usability of geostationary space vessels, making it impossible to patent TV, weather and comm satellites. All his fiction, like the Rama series, is scientifically correct.

Interstellar travel WILL happen, as long as humans continue to exist and wish to continue to exist.


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## Sub_Umbra (Feb 1, 2007)

Maybe, but before we leave we have to figure out how to live long enough to dope it out. Remember, the dinosaurs died out because they couldn't put up a comprehensive SDI.


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## Led_Blind (Feb 1, 2007)

I have asked this question to many people and even thrown in that we dont know everything about science only to be rebuffed by the comment that infect we do know all science and we cannot achieve interstellar travel. 

Having a decent background and interest in science i see this a very odd. There are many principles we do not understand. What is gravity? Why does light act as a particle and a wave... etc. For this reason alone i tend to see all comments on how much rocket fuel etc it would take as ignorance. 

We have soooooo much to learn and we will figure out interstellar space travel eventually. 

I just hope we don’t destroy our own planed in the pursuit.


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## evan9162 (Feb 2, 2007)

Not to mention, once you approach velocities near C, then all of the light/EM waves that you are travelling towards will be extremely blueshifted - the light/energy from the stars that you are travelling towards will be shifted up into the X-ray/Gamma ray range. Without sufficient shielding, you would suffer fatal radation exposure when being subjected to those high energy photons. Shielding against high energy gamma rays requires extremely thick shielding made from materies with high atomic numbers (such as Lead) - so very heavy.


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## JanCPF (Feb 2, 2007)

js said:


> evan9162 is right!
> 
> It doesn't take that much energy to accelerate an ionized atom (even a heavy one) to 99.999 percent the speed of light. Of course, to accelerate it to 100 percent the speed of light would take infinite energy! LOL!
> 
> ...



Great insightful post - thanks. :thumbsup:


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## TedTheLed (Feb 2, 2007)

..just hope you don't pass the Proxima Centaurians going the other way..


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## Pax et Lux (Feb 2, 2007)

I guess it depends if you believe UFO reports are actual sightings of craft that have travelled interstellar space – if you believe _they_ can do it, then you will believe we can, someday.

Personally, I don’t believe that when people see lights in the sky they are observing visitors from a distant star. 

I think the only person to objectively study the phenomena – to read the reports before coming to conclusions – was Carl Jung. Basically, he suggested that when people see lights/shapes in the sky it’s symbolic, not actual. 

Info:http://www.meta-religion.com/Psychiatry/Analytical_psychology/symbolism_of_ufos.htm


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## mobile1 (Feb 2, 2007)

didnt we already leave the solar system or one of our creations.. I think Voyager 1 launched back in teh 70ties is past the solar system already I think


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## DM51 (Feb 2, 2007)

TedTheLed said:


> ...just hope you don't pass the Proxima Centaurians going the other way...


Hmmm. Let's get this straight. I'm heading for Proxima Centauri at 0.9c, travelling in Wave Particle’s colonization ship which is powered by some of js's joules, and half-way there I pass some Proxima Centaurians going the other way also at 0.9c.

It is of course possible that by an appalling stroke of bad luck we collide with each other, which might seem unlikely in the vastness of space but of course you never know – look at that guy a few years back who drove a car across the Sahara Desert and ran smack into the only tree within 500 miles.

But just for the sake of argument let’s say that on this occasion we don’t collide. I’m going one way at 0.9c, and the PCs are going in the opposite direction at 0.9c, so if you add those figures together our speed relative to each other is 1.8c, which is of course faster than light speed. 

Any comments?


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## TedTheLed (Feb 2, 2007)

yup. pic of voyager 1, maybe too big to print here: 

http://nssdc.gsfc.nasa.gov/image/spacecraft/voyager.jpg







"..the Sun; we now know that it creates a bubble called the heliosphere (see image above). The solar wind travels outward at speeds of 700,000 to 1.5 million miles per hour, until it begins to feel the effects of the interstellar wind composed of gas from other stars. At this point, called the "termination shock," the speed of the solar wind slows abruptly. Continuing outward, the solar wind comes to a boundary where the pressure of the two winds is in balance, a point called the "heliopause". Here a bow shock is created like that of a boat moving through water. Beyond the heliopause is interstellar space..."






Voyager 1 and 2 carry a golden record, intended to communicate a story of our world to extraterrestrials. The Voyager message is carried by a phonograph record – a 12-inch gold-plated copper disk containing sounds and images selected to portray the diversity of life and culture on Earth. 

last pic by Voyager looking back at our solar system:

http://nssdc.gsfc.nasa.gov/image/planetary/solar_system/solar_family.jpg


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## WAVE_PARTICLE (Feb 2, 2007)

DM51 said:


> But just for the sake of argument let’s say that on this occasion we don’t collide. I’m going one way at 0.9c, and the PCs are going in the opposite direction at 0.9c, so if you add those figures together our speed relative to each other is 1.8c, which is of course faster than light speed.
> 
> Any comments?


 
If you view time progression as variable, as opposed to fixed, you will find that the limitation defined by the speed of light can be preserved.

Depending on our relative speeds, one second to me is not exactly the same as the one-second to you.

Speed of light (in a vacuum) is fixed, while time is variable.


WP


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## js (Feb 2, 2007)

DM51 said:


> Hmmm. Let's get this straight. I'm heading for Proxima Centauri at 0.9c, travelling in Wave Particle’s colonization ship which is powered by some of js's joules, and half-way there I pass some Proxima Centaurians going the other way also at 0.9c.
> 
> It is of course possible that by an appalling stroke of bad luck we collide with each other, which might seem unlikely in the vastness of space but of course you never know – look at that guy a few years back who drove a car across the Sahara Desert and ran smack into the only tree within 500 miles.
> 
> ...



Yes. You didn't add right!

At speeds that start to become relativistic, you must use a different formula for the addition of velocities.

I hope you didn't ask this question to be annoying. Like the people who love to ask "If you're going at the speed of light and you turn on your headlights, what happens?"

There are two postulates from which all of Special Relativity follows, and from which you can derive the Lorentz Transformations:

1. All observers no matter what their relative motions see light travelling at a constant speed, c=3.0E8 m/s

2. All intertial frames of reference are equivalent and the laws of physics the same for all inertial frames.

Anyway, back to the .9 c colliding with .9 c thing. You would see each other approaching at something like .96 c, not 1.8 c.


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## DM51 (Feb 2, 2007)

Thank you both - I think I have it a bit clearer now, although it's not easy. BTW, my post was not meant to be annoying - it was a genuine puzzle (puzzling to me, anyway)dressed up in a light-hearted way. It is a subject I have vaguely wondered about for a while without ever really bothering to learn more about it.

Presumably if something was approaching you at .96c, the "light" you would see would have severe blue-shift and might even appear as X-rays, gamma-rays or some other extremely short-wavelength EM radiation? Or doesn't the Doppler effect apply here?


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## bfg9000 (Feb 3, 2007)

Pax et Lux said:


> I guess it depends if you believe UFO reports are actual sightings of craft that have travelled interstellar space – if you believe _they_ can do it, then you will believe we can, someday.
> 
> Personally, I don’t believe that when people see lights in the sky they are observing visitors from a distant star.


 Who claims they have to be extraterrestrials? For all we know they could just as easily be evolved human anthropologists from the future visiting the past.




Perhaps we have found them and they are us, though by definition angels... are extraterrestrials.




There are certainly many historical accounts of visitations, and earlier peoples may simply have interpreted such encounters as religious (eg a visit from the Archangel Gabriel, a talking burning bush, a new star in the East) or demonic (ie Lucifer and some of his angels fell to Earth from heaven) in nature, while we are somehow fixated with aliens from our science fiction.





Jung's theory that all people can tap into a collective unconsciousness that contains universal symbols (archetypes) representing all the experiences of the human race sounds like a crackpot idea to me from a biological standpoint, like other theories of Lamarckian "genetic memory." His explanation of flying saucers was they are "disk shaped mandalas" (which was the symbol he defined as representing "completion") imagined by people looking for equilibrium in their lives...


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## Radio (Feb 3, 2007)

I would love to be optimistic and believe that we may someday travel amoung the stars but alass the sad reality is that mankind will probably become extinct long before we leave the solar system.


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## Sub_Umbra (Feb 3, 2007)

I think that the optimists have the advantage.

It's hard to see into the future. _Statistically,_ (and in the long run) I think that throughout history those who opined that some scientific or technological achievement *was* possible were probably right far more than those who said the same *wasn't* possible.

There was no shortage of people who flatly stated that man would never go to the moon or even fly. For tens of thousands of years _nearly everyone_ was certain that man would never travel faster than a horse could run.


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## nerdgineer (Feb 3, 2007)

The Easter Islanders never managed to get off Easter Island by themselves. They just overpopulated until they had a big time crash and then stagnated until "aliens" (the Dutch) with better technology found them.

Physics may have a loophole for starflight and we might even be smart enough to find it someday, if we had the time; but we may well sabotage ourselves Easter Island style before that happens. 

Or there's no loophole. 

So I hope we do, but 2 out of 3 possibilities say....no...


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## Ken_McE (Feb 3, 2007)

*Solar Sails, Bussard Ramjets.*

We don't need to monkey with hyperadvanced physics and hypothetical dimensions in order to go to the stars. Physics as we know it right now permits star travel, it just doesn't make it cheap, quick, or easy. Suggesting that we need to go faster than the speed of light to cross space is like suggesting that we need to go faster than the speed of sound to cross the ocean. 

Our ancestors crossed the oceans in vehicles made of rocks and carefully arranged plant fibers. If they had to, they even skipped the rocks. If it took them ten generations to make the trip, well everything has a price. What price would you pay so your grandkids could have a whole continent to call their own? They didn't carry all their fuel with them, they collected it as they went. No reason our descendents can't do the same if they want.

There are two hypothetical technologies that we can't build this week, but science suggests that they can be built, and history suggests that we may arrive at the point where we can build them within a few centuries.

The first would be the *solar sail*. We know that light exerts pressure when it strikes an object. In everyday life the effect is negligible because we don't have anything movable that is big and light enough for us to see it happen. In space however you can build light weight objects that are really, really, big,

For the sake of discussion let us postulate a solar sail, say a disc ten kilometers across. The sail would be a mylar like material, very light, very thin, and highly reflective. Your payload would sit in the middle and manage the sails. If you build the sail bigger than you really need you get damage tolerance as a bonus. A few acres worth of pinholes should not really trouble you. For cruising about inside the solar system this device and patience would be all you need.

However, we were talking about leaving the solar system, and it gets pretty dark between the stars. For a solar sailor dark = slow. Fortunately, we can fix that. While one team is building your sail you send another team to, oh, how about Mercury? Being on Mercury would give you a place to put things, cheap solar power, and a source of materials.

Mercury has great solar energy and a lot of it, not like that wimpy stuff we get around here. The Mercury team would set up a high tension line running around the equator, then they would set up factories for building solar collectors and high powered lasers. 

After your sail is launched you aim the first lasers at the sail and begin delivering fuel to them in transit. You can send them as much fuel as you like and they pay no weight penalty to carry it. As they get farther and farther away you keep building and aiming more and more lasers. The longer it stays in the beam, the faster it goes. I will leave it to others to decide how long you can keep it in the beam.

For the sake of discussion let's say you can get them up to, oh, .1 C. The laws of physics we all know and cherish permit you to accelerate a big silver disc up to 1/10th the speed of light any time you want. At this speed Alpha Centauri, 4 light years away, becomes a 40 year trip, which is long, but perfectly doable. We are already capable of building machines that can work for fourty years.

The second technology is the *Bussard Ramjet.* I will describe one here that is combined with a generation ship, a ship that houses succeeding generations of passengers en route to its destination.

Lets start out with a big iron rock. There are plenty of them around. Form your rock into a cylinder. A big cylinder. For the sake of discussion let us assume something that looks like a fruit juice can one kilometer across by ten kilometers long. (Rather like the craft in A.C. Clarkes RAMA) stuff it with air, water, dirt, and everything you need to maintain a high tech civilization indefinitely. Give it a 10,000 person crew. Give it spin so that the centripedal effect will act like gravity, making the sidewalls into a big floor. Seal the hatches and start it towards whatever star your solar sail probes said looked interesting.

Now how do you power it? If it just drifts it will be an extremely long time before it gets anywhere and no matter how well you plan and build, eventually something will fail. Let's equip it with one or more fusion reactors. We know fusion is possible because we see it every day when the sun comes up. We can't produce useful controlled fusion at this time, but there seems to be nothing in physics that says we can't do it eventually.

OK, this is a power plant, but what about fuel? Trying to carry all the fuel with you leads to a situation where 99.99% of your entire ship is fuel, which leaves room for, oh, maybe a little gold record saying "Hi" as your payload. This is not acceptable.

We tend to think of space as being "nothing", a perfect vacuum. It is a vacuum compared to what we are used to, but it is not an absolute vacuum. They think that open space contains somewhere around one hydrogen atom per cubic meter. Hydrogen will burn nicely if you have a fusion reactor and a little butter to cook it in.

So how to find useful quantities of hydrogen and collect them en route? You would build a really, really, big honkin' electromagnetic scoop on the nose of your ship and impose an electrical charge on whatever is in front of you as you go along. Once it has a charge you can manipulate it, say with the big honkin' scoop. The faster you go, the more energy you need to increase your speed. However as you go faster you cross through a larger cross section of space per unit time, which means you collect more fuel as you go faster.

Let's assume that our ramscoop can average .01 C. This is slow enough that you do not experience all passing energy as gamma rays, but fast enough to get somewhere. At 1/100th the speed of light you could make Alpha Centauri in about 400 years. Individuals won't last 400 years, but societies do it all the time. The generation who go into the ship will never see the destination, but their descendents will, and now they will own an entire solar system. What would you sacrifice so your descendents could own an entire solar system?


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## James S (Feb 3, 2007)

Ken has the right of it, there is no magic required, no breaking the laws, just a desire to devote the time and materials to the project. It's just engineering, we could get on the road to doing that today if we really wanted to.

Unfortunately, it's slow and difficult enough that we need to know where we're going and more of less what we're going to find there before we leave. No possibility to just bop around to see whats there. 

We have pretty much all we need right here for the next few millenia, and if we were stuck here for a billion years we'd probably be OK. But how boring would that be 

I vote for leaving, for spreading the best that humanity has to offer around a little bit. Which means leaving most of you bums behind


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## js (Feb 4, 2007)

The most interesting thing to me about this thread is not the subject at all--that really doesn't interest me very much; no, the most interesting thing to me is watching the people in this thread and hearing their opinions and beliefs. It's a pretty charged subject, this notion of interstellar travel and exploration!

There are some who say we can't, some who say it's inevitable, some who say we must, and no one yet who says we mustn't. It's all very interesting. Strangely, it's a religious topic in a way!

One religious camp is the camp of the technologists, "religion of science" people. These people have no doubt that science will find a way. It's inevitable. Just look back at history, and then to the present--can't you see the trend? Can't you see that what was once deemed impossible is now commonplace? (And, this camp definitely has a point to make!)

Another religious camp is the camp of the inviolability of the LAWS of physics. What we do know about physics, they say, can not simply be abrogated or falsified--it is proven and has stood the test of time. New scientific theories may cause a revolution in the metaphysics underlying science, but they do not invalidate the old theories in their realm of applicability. For example, Newtonian phyisics still holds good at speeds much less than c--which is most speeds we know. And in fact, we used Newton's Laws to put a man on the moon. We won't ever "discover" that Newton's laws just simply "don't apply". And, this camp also has a point to make.

And another religious camp is the camp of the esoteric, of folding space and worm holes and warp drive. Or entirely new realms of reality in which the limitations of regular space-time do not apply. They point to string-theory and quantum cosmology and other such very cutting edge musings by physicists. And, of course, this camp has a point to make as well. I mean, there was a time when we knew absolutely nothing about the non-visible, non-heat, portion of the EM spectrum. Radio waves, X-rays, and so on.

I myself would not fall into any of these three camps, although I think each camp has a point to make.

But I can tell you one thing! I won't be one of the people on a ramjet making a multi-generation journey to some other solar system! A trip measured in days to go to the moon and back is one thing. A trip measured in lifetimes to go to the nearest potentially inhabitable solar system, never to come back, is entirely another.

And consider that even if YOUR time is dilated and the journey doesn't seem to take too long in your time, when you return to Earth, many more years will have passed.

The Earth is literally priceless, literally peerless. We won't ever be able to just ditch it and move somewhere better with the ease that we abandon a town that grew up around a strip-mine. Even if there is some eden of a planet in another solar system, it's more than a world away, more than a lifetime away, more than just a long journey.

Science doesn't have (and never will have) all the answers, or even the most important! Technology can not (and never will) solve all our problems, especially the most important. Not to mention that technology has a nasty habit of creating new problems even as it apparently solves others.

We need to start paying more damn attention to the planet we do have and what we are doing to it, and failing to do for it. Dr. Seuss's "The Lorax" (mentioned before) should be required reading indeed.

"Will we ever leave the solar system?" At this point, it's pretty much beside the point, isn't it? Revealing? Yes. Interesting? Perhaps. Important? No.


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## iveseenthelight (Feb 4, 2007)

I guess one of the most depressing things about this concept is that none of us here will ever be able to see these achievements. I personally think that we will eventually venture out beyond the solar system in a way similar to how Ken described. We will have to sacrifice people's lives to get the job done. Interestingly, the people that reach the new solar system won't have any of the same concepts of earth as we have. They would have something in common with the life forms they encountered in that they have never even been on earth. They wont understand living on our planet and venturing out as they have lived their entire lives on a ship in space. They will most likely never personally visit earth yet they will be the most impotant human explorers in world history.


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## rotncore (Feb 4, 2007)

No, I don't think we will...fossil fuels will be our constraint. World oil supplies are at or near peak, and all the technologies we take for granted are at some stage highly dependent on the cheap energy from oil. We'll be too busy trying to maintain our current standard of living to take on ambitious projects like space travel. Yes I'm a peak oiler.


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## Sub_Umbra (Feb 4, 2007)

JS,

I think the religious analogy is pretty good but your post poses some heavy philosophical questions that will be important in determimning whether we leave or not:

 How do we _really_ feel about our decendants? Many who have kids routinely make noises like they think that just having kids will insure that at least a part of them will go on forever -- yet they live in a solar system which will not last forever. (I would be the wrong one to ask as I don't and won't have any kids) What does this talk about 'living on through our kids' really mean to them and how serious are they? How many serious ones _are there?_
 If we dodge species killing events created by ourselves and the ones originating off-planet, will making a trans-generational or perhaps even never-ending journey look any more inviting to those living in the times closer to the end of our sun? Will everyone want to give up the often referred to idea of 'living on through their children' -- and just lie down? 
 Will we always feel the way we do now? Will we always act the way we do now?
I'm playing Devil's Advocate here. I'm not the ultimate cynic -- but he's a friend of mine.  I do think that these are interesting questions, though admittedly in a somewhat abstract, detached sort of way since I don't have much of a dog in this fight. I would still like to hear how others feel on these questions.


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## RoyJ (Feb 4, 2007)

So, why the heck do we want to go to Alpha Centauri again?

C'mon, I'm sure that place sucks. Nothing good to eat, no parks to relax in, and no where to buy lithium cells if our flashlights run out of power...

And never mind that with our politicians today, we won't last long enough to have the technology to go there efficiently.


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## RoyJ (Feb 4, 2007)

delete double post


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## WAVE_PARTICLE (Feb 4, 2007)

RoyJ said:


> And never mind that with our politicians today, we won't last long enough to have the technology to go there efficiently.


 
Truer words have never been spoken. The only time our politicians (worldwide) will band together to do something about our planet will be when it's too late.....and it will be our great-grand children who will pay the heaviest price.

:thumbsdow 

WP


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## Flying Turtle (Feb 4, 2007)

I'd like to think we would eventually find a way to do it, or at least terraform and colonize Mars. Unfortunately I think the odds are greater that an asteroid, solar flare, lack of resources, or global nuclear war will ultimately beat us before we get a chance.

Geoff


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## chesterqw (Feb 5, 2007)

rofl, i won't doubt it.


but, when will humans ever stop thinking about leaving the solar system?


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## tygger (Feb 5, 2007)

wouldn't it make sense one day for humans to become completely inorganic? i'm thinking something similar to the beings at the end of the film "AI" where the future "humans" communicate telepathically and look to be made of some fluid artificial material. anyway, my point is that wouldn't space travel be ideal if humans, and whatever it means to be human, could exists in some non-organic material form? if we could somehow replicate or duplicate the human brain for example, what would stop us from "downloading" all the information to that inorganic storage media? that way you'd be able to live forever as long as you could keep transferring your "memory" to future brain upgrades. i know it may seam the be in the realm of fantasy, but with humans becoming ever more complex cyborgs (artificial hearts, hearing aids, etc,) if we continue along this path, wouldn't it make sense for us to keep "upgrading" our bodies to the point where our "parts" would be so advanced they could be interchanged at will? just a thought.


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## Lit Up (Feb 5, 2007)

chesterqw said:


> rofl, i won't doubt it.
> 
> 
> but, when will humans ever stop thinking about leaving the solar system?



Not sure, but this pic always gives a glimpse to the daunting task at hand.






That white, tiny spec you see in the orange beam....is us.


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## grapplex (Feb 5, 2007)

...

http://www.spaceweather.com/comets/gallery_mcnaught_page14.php


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## WAVE_PARTICLE (Feb 5, 2007)

:duh2: I have another theory:


Perhaps over the next few millenia, Man shall evolve to the point when his Mind can process the fact that Time is no longer a Journey, but a Destination. If the expedition beyond our Solar System is to be achieve, it is because Man chooses to, not due to desire, but merely due to the possibility.

The vastness of space and the perceived colossal scale of time is irrelevant. Just as one can traverse through a room from one point to another simply out of choice, so too shall Man traverse through time.... Time is as ubiquitous as space itself.

If inter-stellar travel is possible, it will be and has already been done. 


:duh2: WP


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## TedTheLed (Feb 5, 2007)

Grapplex,

philosophy, pics;

wow mom..! 

(gotta wonder what the freaky stuff was!?)


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## James S (Feb 5, 2007)

Whoa  cool man. I've noticed many substances and meditation techniques can alter our perception of time and space, but so far none that alter our actual position in it  It may very well be that time and space are just metaphors for a higher level of reality, but as long as we're stuck here inside the machine as it were, our engineering projects have to live with the rules as set forth by the machine.

Unless we really crack our own local longevity problem I doubt that in the range of future where humanity is still recognizable as such that we'll bother. Unless a way is found to go a lot faster than is possible. We just dont spent those kind of resources on projects that have no payoff in our or our childrens lifetimes. It would take an obvious oncoming disaster in our own solar system to make us want to do that. We just dont think that far ahead. So lets hope when the motivation strikes us that it is for a better reason.

That being said, the cost of engineering comes down all the time. Our building blocks and building tools get better every day. There will come a time when designing something in the computer is the last step before building something that requires a person to work on it. Dump in the raw materials and a generation ship could squirt out the other end. If you found a planetary system you wanted to go to, I"m sure that a crew could be found willing to make the trip.


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## js (Feb 5, 2007)

sub,

Here are my answers:

1. I don't know.
2. I don't know.
3. Probably not. Probably not.

grapplex,

Anyone who has ascended to the level of consciousness and ability you describe has no need of a space craft or other technological construction to journey outside of the material reality most people commonly think of as "Earth" or even "the solar system".

Right?

And if so, then clearly, humans already have left the solar system. Heck, as I recall from Paramahansa Yoganada's "Biography of a Yogi" his master returned to him in a vision and described his new work on another "planet" or plane of existence helping those very advanced students who had already progressed to the point where they no longer needed to reincarnate on the material plane at all, moving on to astral and causal planes. And that's just one example. Not to mention what happens to the soul after death.

However, this is not what the poster of this thread had in mind, nor what most people think of when asked the question "Will we ever leave the solar system?" . . . LOL!


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## Ken_McE (Feb 5, 2007)

Lit Up said:


> That white, tiny spec you see in the orange beam....is us.



Now *that's* what I call a beamshot.


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