Hacker News Reader

I love absolutist comments like this. Never is a very very long time. Its possible we already were visited and they've moved on. What most folks don't conceptualize well is that the width of the timeline which constitutes "humans are here" is so damn small on a 4 billion year timeline as to be hard to spot with the naked eye :-).

But lets look at your points: 1) You don't have a good grasp of physics but that's ok. One of the things that happens as you accelerate is that you gp through something called time dilation. Travelling a significant fractions of the speed of light will have time passing much much more slowly on the ship than on Earth. You'll want to work it out so that you approach 'c' at the halfway point, then flip over and decelerate. If you do it that way your crew will easily survive the entire trip. There is the question of energy and reaction mass, real problems and as yet unsolved, but not insoluble. We can and do regularly manufacture anti-matter these days, its a pretty good fuel.

2) You make a number of interesting assumptions here. One is that aliens are 65 million miles away. Consider that we already know that our planet is a death trap, its killed off everything several times already, so we figure out how to leave. Better we create our own environments where all we need do is scoop up interstellar hydrogen for fuel, or perhaps harvest a bit of space junk. The Earth is a spaceship that is gravity locked to the Sun. There is certainly enough material in our solar system to build something that could wander amongst the stars. And if we've figured out cellular biology, and can thus 'fix' any issues that come up, it means we can 'live' in our bodies forever via mechanical repair. If we can do it, so can other species. Imagine a flotilla of 'units' moving in parallel, carrying our alien visitors, from star system to star system. Perhaps seeing a new system every 100 years or so.

3) We can certainly create habitats that don't kill us and that keep things that might kill us out. Further there is a really really interesting change coming when pieces of how people work comes together in a provable way. One good thing, the health care crisis for 'rich' people will be gone. Once we've got the source code, all bets are off.

4) This is just projection ;-) We would go visit a society that was in its early stages of development just to see how they do it. We've been doing that with indigenous island people on the planet, I would be surprised if we had interplanetary capability and we didn't do that.

Upvoted for your futile human attempts :P. I still disagree with your rebuttal. Yes, I did use an absolution word like "NEVER". But only because we have a limited time on earth before another massive extinction event occurs and realistically solving all the problems with space travel at light speed have such a tiny percentage of being solved that you might as well say its impossible for the sake of being realistic.

Lets look at your rebuttal:

1) Time dilation doesn't solve ANY of the impossibilities of traveling at light speed. Even the Earth, with its massive atmospheric force field and magnetic field only travels at 67,000 mph and still gets pummeled with meteors, natural space debris, and massive amounts of radiation that, despite being filtered out by a magnetic field thousands of miles thick, still delivers radiation. A tiny particle the size of a ballpoint from a ballpoint pen is nothing to fear, but when that particle is hits anything at light speed it is deadly. If there is 1 piece of space debris every 1 mile in space and you're traveling at light speed, the ship, no matter what it's made of is going to disintegrate when it gets hit with 11.1 million pieces of debris every minute. At that speed nothing can be deflected by shields all objects will disintegrate and rip the ship and crew apart.

Back to radiation: With 2 hydrogen atoms per cubic centimeter in space, at light speed the radiation exposure increases 100,000% PAST THE LETHAL LIMIT for humans. We would die of radiation exposure immediately. It would also destroy electronics on board. And NO, building an artificial force field is not going to work either. At light speed it will be useless. Also no force field of any kind will work or be able to work at such a high speed.

2) Still doesn't solve the unfilterable radiation problem, space debris problem, emotional toll, and cost. Granted things WILL improve in the future. They usually do. The problem is, we're both assuming that we will still be around long enough to figure this stuff out. Yes, we humans are smart and resilient but we live in an opportunist world where the longer any species stays alive (humans) the more counter-species (viruses/plague/bacteria) evolve to feed off of and kill the former species. We've extended our stay for quiet a while and are just now starting to feel our eventual fate with the rise of super viruses, antibiotic resistant bacteria, and super flus. And it will only get worse. As we evolve our microsized enemies do too. Lets not forget we're also self destructive.

3) Agreed, we could create habitats that don't kill us but this is assuming we actually reach another planet. Which just isn't going to happen.

4) We would go visit a society that was in its early stages of development just to see how they do it. At the cost of trillions of dollars and the lives of thousands, possibly millions of people over the course of thousands or millions of years. I don't think so.

I fully agree with you. While all of this is possible in theory, there are so many things that could go wrong, and one single mission would cost trillions.

Only if there is some extraordinary law(s) of physics that would open up entirely new methods of travel (and so many other things) would any of this be possible.

I still would like to spend a big chunk of my tax dollars on NASA, etc, but the idea that there is intelligent life out there, and it is likely that we are going to contact it, seems like nonsense to me.

I'd love it if we did, but I just don't think it's going to happen. And that's ok. Some people really seem to have an emotional horse in this game, I'm not sure why.

"Some people really seem to have an emotional horse in this game, I'm not sure why."

I think it's because no one likes being told what their limits are. And when faced with certain inevitable death humans will fantasize their way out of it to make themselves feel better. Even if it's illogical or obviously impossible. (ex: "When I die, I'm going to go to a magical place in the sky where there is no suffering, no pain, no death, no bad things, and I will have everything I want, and I will be happy and live there with all my friends and family forever." - Human fantasizing about "heaven"). And there's nothing wrong with that. We're only alive for so long, might as well spend that time being happy. It just sucks when people bring fantasy desires into scientific reality.

A MAJOR point I forgot to mention in my original post. If planets and suns existed forever then yes we might be able to work something out, even if we're not traveling at light speed. But the delays, distances, and time limits involved are what make all of this near impossible. We only have a few billion years before our sun starts entering into its red giant phase and burns away our home. A few thousand before another extinction event, and possibly few thousand before getting hit by a massive meteor. Whatever planet we find looking through a telescope will have its own time limits, it's own problems that we won't know about until its delayed and outdated light finally hits us. It's the delays, it's the distance, it's the time limits. Everything has to fall into place so well. And with no planet known 100% to sustain life, everything is a gamble with insanely impossible chances to win.

The distances are so massive in space, the time delay between sending a message just light years away and getting it back makes the gamble worse. Imagine starting a voyage and midway finding out the planet has been destroyed or has entered a massive extinction phase that will escalate when we get there. Or finding out the planet is no longer inhabitable. Lets not forget our own Earth has entered periods where it was one massive boiling ocean, one big icicle, a bunch of lava. Granted we've moved away from those periods towards stability. But what if the planet we're heading towards destabilizes while we're on our way there?

Most people are visualizing space by what they've seen in star trek or star wars. With percentages of failure and death completely missing from their mental image of what it truly means to travel in space. People see it as a game of patience. When it's really a game of 'ALL of the odds are stacked against you and continue to stack against you the longer you stay out there'.

The more I think about this the more I realize how really lucky we are being on Earth. Really really lucky.

> these radiation particles are SMALLER than x-ray particles

This indicates you might not understand enough physics to be able to back up your assertions. Firstly, X-rays are in the same category as "radiation particles" (I assume you are referring to electromagnetic radiation). Secondly, radiation "particles" are photons and they don't strictly have a size; they do, however, have a wavelength, which might be what you are alluding to?

(And lastly, if particles "pass through absolutely everything", they do no damage and so aren't problematic.)

> If an extra terrestrial landed here on earth they would not be able to interact with us in ANY way without wearing a bio-suit. They can't breathe our air or drink our water. And you think they're going to travel millions of years to get to a planet they can't even vacation on or enjoy or interact with in any way.

They can vacation on it and enjoy it by wearing a biosuit. And this isn't unreasonable: humans can't breathe water, but we still can enjoy it using a biosuit (SCUBA equipment).

they do, however, have a wavelength, which might be what you are alluding to

Yes, thank you for correcting me. Cosmic radiation comes in all sorts of varieties from the very powerful (that passes through nearly everything to the less powerful. From my very basic knowledge of x-rays, they can pass through or stay in the body. Then can also affect tissue they pass through which is why too many x-rays are bad.

"humans can't breathe water, but we still can enjoy it using a biosuit (SCUBA equipment)"

True. But how would you like for you and your entire family and ALL subsequent generations had to live either indoors or in a scuba suit for the rest of your lives?

Also while in space, as cosmic radiation passes through an astronauts eyes and brain they see flashes of light. Even with their eyes closed. Going at light speed would mean an almost constant white out. This is despite shielding space shuttles from radiation as much as possible.

All your points are based on limitations particular to human understanding of physics and technology.

Just as a microwave oven is practically magic to a caveman, it is reasonable to assume that our tech is caveman-tech to an advanced alien race.

Why travel at the speed of light, for example? Maybe wormholes or teleportation is possible?

Magical concepts from science fiction, sorry theoretical concepts from educated guesses based on current (incomplete, unproven, un-seen) understandings of the universe. If such things existed intelligent life would have used them to reach us.

Maybe they wouldn't be interested in us. Certainly there are some people here on this Earth that I wouldn't want to meet (for instance some of my relatives).

"If such things existed intelligent life would have used them to reach us."

For what reason would we be a magnet for everything out there to have to come visit us (the assumption being that if they don't visit us it can't be possible because we are somehow too important to ignore)? It's a rather flawed basis for an argument.

Our communications out don't speed up getting to them because their ability to get to us has. There is no reason to assume anyone knows we exist yet.

The assumption is if you have a FTL civilization you vary quickly grow to the point where you go just abut everywhere you can reach with FTL travel, unless something else was already there to defend it. Extinction becomes really hard when individuals are being sent out faster than just about anything that could catch them.

I fail to distinguish your magical concepts from sufficiently advanced technology.

They have may be a very correct prediction that we are a parasite-like race in terms of spiritual advancement and do not live in harmony with our provided environment, and thus, it is best to not touch us till we learn to not kill everything we touch for our own pleasure.

There may be many reasons why an alien race does not automatically make contact, some of which are actually unknown to us. If you have difficulty swallowing the "some things can be unknown to us" thought, believe it or not, you have an ego problem.

We have found planets that may support life 20 light years away. Recent evidence suggests that most stars around us have planets and a significant percentage of those stars have planets that may support life. It's just that resolving a planet at those distances is hard, let alone radio traffic. So while we have little chance of contacting life 1 million light years from us there is a chance intelligent life with technological civilizations could be within as little as 50 light years of us. And even if they exist we would probably have not noticed them yet.

We might never have physical contact with civilizations a 100 light years from us we could have meaningful if high latency conversations with them at reasonable costs.

PS: It's hard to talk with Voyager 1 a mere (1.8x10^10 km) from us at 50 light years the signal would be 1/700,000,000th the strength. So, the only way your talking out to that distance is with a dish that's pointed in the right direction and even then if the signal was not 1 million times as strong there is no way in hell we would notice it.

20 light years is still 20,000 years of traveling in space even after taking into account that technology and speed will improve over time by about 90%-100%.

Who and what government would go on a suicidal safari to another planet which "MIGHT" support life which will take trillions and trillions of dollars, and 20,000 years to reach? First it may not be possible to have children in space even with artificial gravity. Second, the radiation would kill the child before he can even speak his first word.

Even if through a magical genie we solved these problems and avoided cancer... Would you feel comfortable living on a space ship for the rest of your life? Bringing children into this world knowing they'll never have a normal life like back on earth. Sacrificing not only your life but the lives of thousands of your 1,000+ generation grandchildren so you can go explore a planet that you think "might" have life.

Assuming we end-up with reasonably efficient fusion power and an even mildly space based economy we are eventually going to start mining the ort cloud. Which set's up a natural path to vary slowly expand into the stars.

Basically, if it's profitable you get exponential growth till it's not and even slow exponential growth ends up with ridiculous growth numbers fairly quickly on a geological timescale let alone a galactic one.

Just remember that "normal life like back on earth" sucks balls for most of the people on earth. If there was a ship on the pad, there would be a line around the block that made "American Idol" auditions look like a small, intimate gathering.

Most of your points are sound, but I think you are too pessimistic about them being interested in us. Mightn't they be just as desperate as we are to not be alone?

exactly.

> Extra terrestrial life that is more advanced than us has no reason to go on a suicide mission to come see us (a bunch of war-mongering primitive hairless baboons)

Just as advanced western scientists have no interest in going on biology field trips to remote parts of the world to study lesser species.

Traveling on your own planet (which is easy and cheap) and traveling to an unknown planet in space which costs trillions of dollars and takes a minimum of 20,000 years are two very different things. Lets keep things in perspective now.

Traveling a few hundred miles to see a creature you can stand a few feet away from, touch, and study /AND/ traveling for millions of years, never seeing the fruit of your labor so that your great X 1,000 grandchildren might be able to reach a planet they can walk around on in an air tight suit for the rest of their lives, then send a signal back to earth which will take 20 years to reach. That's a whole new "field trip".

Where are you getting this stupid 20,000 year figure from? Even with current tech, we can travel at 0.1c easily, that is without any extra effort made in actually travelling outside our solar system. Near-by candidates are within 20ly, so at min it would take just 200 year, or 3 human generations.

And if it might give you some peace, there are thing called machines that can be built to contact other civilization without sacrificing your hypothetical children.

  > we can travel at 0.1c easily

Can we? I mean as humans, not just some spacecraft. We can also sustain closed ecosystem for three generations? Last I heard an attempt to do that on Earth failed.

> We can also sustain closed ecosystem for three generations? Last I heard an attempt to do that on Earth failed.

Most things fail before they succeed.

I'd love to know how we can "easily" get a spaceship up to 0.1c using "existing" technology.

[NB I wouldn't consider the Project Orion approach "existing" technology, it hardly got off the drawing board and was never tested with anything other than chemical explosives on a very small scale].

If you felt alone, would you risk your life savings, and life to go visit a chimpanzee in a war torn, unstable, volatile 3rd world country whose jungle contains malaria carrying mosquitoes, has a life expectancy of 23 years, and gives you a high chance of being raped, killed, or infected with incurable disease?

Maybe. Depends on what kind of protection my life savings can get me, and whether I have anything else to do. :)

Perhaps you lack imagination. The first argument has been addressed by many, and in an interesting way by Alastair Reynolds in his Revelation Universe.

Ships apply 1G of acceleration for many years and thus slowly reach speeds close to that of light. The ships are both "aerodynamic" and encased in a thick layer of ice, so that small, rare impacts are survivable. This becomes a plot mechanism in a few of his stories.

"Perhaps you lack imagination."

Possible, but I doubt it. http://www.chrisnorstrom.com

Ice won't do anything about the radiation. At that speed aerodynamic doesn't matter either. Nice try human ;P

I didn't imply you lack imagination in general, just imagination on this particular subject.

Radiation is a separate matter. That speed is precisely where aerodynamics start to matter again, as you hit stray particles. You want your profile to be as narrow as possible, so you're hitting as few particles as possible.

Ice helps absorb the impact of such particles.

Note that Alastair Reynolds is an astronomer, so he did think this bit through somewhat.

My favorite part: And you think they're going to travel millions of years to get to a planet they can't even vacation on or enjoy...

While radiation is a serious problem at relativistic velocities, you're a bit too pessimistic:

The most immediate problem is the interstellar gas, which becomes hard radiation at relativistic velocities. However, ~2cm of aluminium shielding are enough to reach 0.3c, and with 1m of water, you can reach 0.5c.

For higher velocities, magnetic shielding coupled with a metallic electron stripper is probably a more pragmatic solution.