August 19, 2008
Interstellar Travel Seen Unlikely

Getting to another lifetime seems unlikely even using the most advanced technologies.

The major problem is that propulsion -- shooting mass backwards to go forwards -- requires large amounts of both time and fuel. For instance, using the best rocket engines Earth currently has to offer, it would take 50,000 years to travel the 4.3 light years to Alpha Centauri, our solar system's nearest neighbor. Even the most theoretically efficient type of propulsion, an imaginary engine powered by antimatter, would still require decades to reach Alpha Centauri, according to Robert Frisbee, group leader in the Advanced Propulsion Technology Group within NASA's Jet Propulsion Laboratory.

Why go in the first place? Unless we could know in advance that travel to another solar system would provide us with a planet suitable for colonization what is the point in going? We have other types of planets to visit in this solar system. So we go to another solar system and it too has gas giants. For this I'm going to sit in a spacecraft for 50 years? I don't think so.

The development of rejuvenation therapies will eventually make it possible to travel to another solar system and live to see your spacecraft reach its destination. Though success will require design of spacecraft that are highly reliable for decades. Do not step on board until mean time between fatal failures is measured in the hundreds or thoiusands of years.

There's always the possibility that a discovery in physics will let us travel across the galaxy via another dimension. Hard to guess the odds of this happening.

You might be saying "but what about the opportunity to meet space aliens?". But there's a problem: either your microbes will kill them or their microbes will kill you. The odds of living on the same planet as creatures from another world seem pretty remote. Besides, they might be extremely xenophobic killers who enjoy hunting down and killing other intelligent species.

Share |      Randall Parker, 2008 August 19 10:45 PM  Space Exploration

Finnsense said at August 20, 2008 12:48 AM:

It's likely that humans will be very different creatures at that point. In fact, homo sapiens will probably only exist for another 100 years or so. Within that timerame we will be able to download relevant aspects of our "selves" to a computer and then carry on going in an artificial body. Alternatively, we will just be genetically engineered to be "better" or there will be some mix of biology and computer.

You shouldn't worry about being bored to death in a spaceship either. Drugs that will make you cheerful in such a situation are pretty close.

Mthson said at August 20, 2008 12:56 AM:

As long as the ship has broadband, it wouldn't be too bad.

Ted said at August 20, 2008 1:21 AM:

I suggest with ask Multivac ASAP.

Aron said at August 20, 2008 3:20 AM:

"either your microbes will kill them or their microbes will kill you."

Where the heck did that come from? That's about like expecting Microsoft Windows to run on an alien built computer without changing it. Outside of hollywood that doesn't work.

jb said at August 20, 2008 3:32 AM:

re: microbes: I suppose its possible that our microbes could kill each other, but that seems very unlikely, unless we're all seeded from the same intergalactic DNA source. And even then, evolutionarily, their 'cellular' structure will probably be so wildly different from ours that digestion will be impossible. Let alone viruses, which require an almost perfect match with the host to work at all.

To put it another way - there are lots of viruses and bacteria and fungi that attack orange trees, that have no meaningful affect on humans at all. And aliens are going to be far, far, far different from us than we are from orange trees. Based on my (admittedly weak) understanding of biology, it seems most likely that we'll be completely genetically incompatible with each other, although we will probably smell really, really bad (and vice versa).

re: space travel - I can imagine a machine that could store a human consciousness, and maintain vats of chemicals that could build human bodies on demand, and establish the neural networks in the brain to match the stored consciousness. Without the need to protect fragile organic structures, a spaceship with this machine could accelerate at several gravities, and then recreate the human passengers at the far end.

JoeKing said at August 20, 2008 6:00 AM:

"and if man was meant to fly....."

What about the indomitable human spirit? This article only demonstrates the limited imagination of

Brock said at August 20, 2008 7:36 AM:

...microbes: the microbes that gave my dog bronchitis last week have no effect on me. That's normal - microbes very rarely jump from one species to another (bubonic plague and bird flu being two of the rare exceptions that prove the rule). And chickens and rats are pretty much exactly like humans in many respects. The odds of a alien flu seem pretty damn low.

...a planet suitable for colonization: once humans figure out how to colonize the asteroid belt or a gas giant, I'm pretty sure that any star system with energy and mass will do.

I agree with JB. Barring a "physics breakthrough" like practical warp drive or hyperspace travel, it will be easier to propel a small assembler (perhaps using a laser sail; most of the sun's energy output is off the elliptic plane and "wasted" from Earth's point of view) to another star system. It won't carry humans, just the instructions for making humans (maybe even specific humans). Bits are low-mass. Once it arrives at the new system it can start nano-assembly of O'Neil cylinders, people to live in them, and copies of itself to spread humans via Von Neuman Probe throughout the galaxy. If it takes a quantum entangled radio with it we'll even be able to talk with these other colonies in real time.

Allan said at August 20, 2008 9:37 AM:

First of all ... I remembering reading an old article when some scientist way back when that it would be impossible to go faster than 35 mph or so because the human body wouldn't be able to withstand the force of the wind without breaking.

Just because we don't know how to do it know doesn't mean someone won't discover FTL propulsion in the future.

Remember, gas giants often have large moons or even small planets circling them. If we can live on the moon or Mars, we can live almost anywhere ... just need the right stuff and plenty of supplies to start us off.

Finally, it is unlikely that an alien microbe or virus would infect us just as a virus that gets a dog sick won't get us sick. Possible ... yea, I suppose ... likely ... naw.

Ad Astra!

kurt9 said at August 20, 2008 9:59 AM:

This Wired article is so mindless I don't even know where to begin.

First, I believe the issue of whether planetary surfaces are even desirable for technological civilization was discussed in the 1970's. The L-5 Society was the result of this discussion. Bear in mind that O'neill's scenario was based on boring 1970's materials science and manufacturing technology. This means that one does not have to find an "Earth-like" planet. One only needs to find lots of comets and asteroids for building habitats. This does bring up the question of if we can build habitats in our own solar system, why do we need to take the trouble to go to another solar system. There is no mention of O'neill style habitats in the article.

Second, that the government bureaucracy called NASA has not developed low-cost space transportation does not mean its not possible. The energy required to put a kilogram into orbit is the same as transporting that kilogram from LAX to Sydney. Every time I fly in and out of LAX, I notice Quantus's "long reach" jumbo jets at the international terminal. There is no technical reason why this is not possible with space transportation. Having NASA in the space transportation business is like having a single, government own airline. If aviation had developed in this manner, we still would not have commercial air travel. NASA exists solely to employ 20,000 civil servants until retirement. Any other purpose is incidental to this objective. Familiarize yourself with Jerry Pournelle's Iron Law of Bureaucracy.

Third, there are speculative schemes utilizing fusion and/or anti-matter propulsion that can get to respectable velocities for interstellar travel (0.1-0.3c). Robert Forward proposed two of them (laser light sail and anti-matter propulsion) in the 80's. Both of them had engineering merit and, as far as I know, have not been discredited on technical grounds. The Wired article fails to mention this. Now travel at 0.1c still means travel times of 40-100 years to get to the nearest stars, but this is not insurmountable. Also, the article neglects possibilities such as embryo space colonization or the use of some kind of cryo-preservation as means for reducing the payload size of the starship. It also neglects any possibility of self-replication manufacturing (which does NOT have to be based on Eric Drexler's nanotechnology) that would be needed for building the infrastructure in the target system, regardless of what technology the starship is based on.

Given that this article is based on comments and presentations by NASA scientists and engineers, the only conclusion I got from the article is that NASA should be immediately shutdown.

Allan said at August 20, 2008 10:17 AM:

Sorry about the double post ... connection problems.

Kurt9 ... As someone who a member of the L-5 Society, I completely agree with you. Great post.

Dennis Towne said at August 20, 2008 10:18 AM:

I've thought at lot about interstellar travel over the years, and done a lot of research. As I've gotten older, I've also completely abandoned the idea of sending actual human bodies across such distances. It's a colossal waste of resources to do so.

I definitely wouldn't try to send this body were I to attempt such a thing. I'd make a copy of myself in silicon or other hardware, load it into the smallest reasonable ship that could bridge the distance and perform its desired function, and send that instead. With a small enough ship, it would be possible to laser boost the ship on its way out of our solar system, and deploy sails at the destination to shed the excess velocity.

As a previous poster pointed out, bits are cheap.

One comment about the previous post proposing quantum entanglement to get real-time communications: that doesn't work. The light-speed delay problem will continue to be a major issue, and IMHO FTL technology won't be possible.

David Friedman said at August 20, 2008 10:38 AM:

Did the calculations assume that the ship had to carry its own reaction mass or did they include ramjet designs, using interstellar hydrogen for reaction mass, or a light sail powered by a laser canon in the home system? Both of those seem potentially more plausible than a simple rocket, even with anti-matter for fuel.

Also, note that if you have an external source of matter available, such as interstellar hydrogen, the effective energy content of your antimatter battery is 2mc^2. The more reaction mass you have, the more gently you can push it, and since energy goes as v squared and momentum as v, that means that in the limit of infinite reaction mass all of your energy ends up in the spaceship.

If you start with half your ship an anti-matter battery, that means that you end up at a velocity at which the relativistic mass of your ship is three times what the rest mass (not counting the battery, which at that point has been used up), so your velocity is well over half c.

Of course, that still leaves you with the problem of braking.

TangoMan said at August 20, 2008 12:26 PM:

Within that timerame we will be able to download relevant aspects of our "selves" to a computer and then carry on going in an artificial body.

Thus enabling genocide with one powerful EMP blast.

TomO said at August 20, 2008 1:15 PM:

That's about like expecting Microsoft Windows to run on an alien built computer without changing it.

Should work fine, as long as it's written in java, right?

kurt9 said at August 20, 2008 2:18 PM:

Frisbee, one of the presenters mentioned in this article, made a decent presentation. It is available at:

His presentation appears to be a pitch for research into what is charitably called "exotic" physics and for the Breakthrough Propulsion Physics program. Unfortunately for him (and us), funding for the BPP Program was terminated a few years ago.

Bugged_Out said at August 20, 2008 6:44 PM:

"It's likely that humans will be very different creatures at that point. In fact, homo sapiens will probably only exist for another 100 years or so. Within that timerame we will be able to download relevant aspects of our "selves" to a computer and then carry on going in an artificial body."

So I could live near forever in a robotic body? Does that mean no more sex? Ugh.

David Govett said at August 20, 2008 9:26 PM:

Once humans move into virtual reality, why risk interstellar travel? Everything you want, when you want it. What more could one ask?

Aron said at August 20, 2008 11:06 PM:

"So I could live near forever in a robotic body? Does that mean no more sex? Ugh."

The number of appendages allowed to a robot is up to the imagination of the designer. Just learn from the tin man and bring your own oil can (or other lubricant).

Tj Green said at August 21, 2008 6:55 AM:

I think the international collaboration at CERN will give us a much greater understanding of our universe. If we find that we cannot exceed the speed of light then is it really that bad? How long did it take our species to colonize every continent? In nineteen days the Large Hadron Collider will be ready for business, with the the worlds most powerful super computer to interpret these proton collisions. We could know by the end of the year if there are extra dimensions or not. Our species is about to take a giant leap forward.

Wilf Clarke said at October 2, 2008 1:37 PM:

It has been said that,a spaceship traveling at 20,ooo mph,would only move about an inch on a computer instruction,
in comparison to the speed of light.Is this true,if so how do they work it out,? I would realy like to know.

Wilf Clarke said at October 2, 2008 1:38 PM:

It has been said that,a spaceship traveling at 20,ooo mph,would only move about an inch on a computer instruction,
in comparison to the speed of light.Is this true,if so how do they work it out,? I would realy like to know.

Josh said at February 14, 2009 3:52 PM:

Fusion rockets can go a tenth the speed of light, and antimatter rockets can go as fast as you like short of the light barrier. And if you use other methods, like magnetic sails, you don't have to worry about carrying fuel with you.

My problem with interstellar travel is meteoroids. The interstellar medium is not as empty as we like to think. We don't know what's out there. There could be rogue asteroids, rogue planets, more comets, etc., out there, and we wouldn't know it until we got there (which may account for the so-called "missing mass" of the universe).

An asteroid in the belt goes 30 km/sec, or about 1/10,000 the speed of light. If we went even 1% the speed of light (which would require 430 years to get to Alpha Centauri), then a meteoroid would hit the ship with 10,000 times the force of a meteoroid of the same mass in, say, Earth's orbit. This means a meteoroid of about 100 grams would be as catastrophic to the ship as a one-ton meteoroid would be to a space colony.

And how would the ship get the materials to repair the new hole, which would probably be the size of a barn door?

Plus, if the trip lasts for centuries, how can we make sure the ecology and the machines will last that long before breaking down?

I think the only way to travel between stars is to use science-fictional devices such as hyperspace travel and wormholes. Even then, I'm not sure how such things would work; I mean, who says the ship wouldn't end up in the interstellar Middle of Nowhere?

After I told my mom all this, she said it's probably God's way of telling humans to stay home. :)

Denise Holdsworthy said at March 25, 2009 10:56 PM:

Maybe NASA have done more than we are told? Or maybe they know more about aliens:

Mr Hayman said at November 18, 2010 10:48 AM:

Hey all,

I am glad to see I am not the only one who thinks NASA and other space scientists have no imaginations.

If your interested in interstellar propulsion and advanced propulsion, you will probably find my website interesting.
I have not been afraid to think outside the box, and have many examples of other people who have done the same.

Not everyone is as narrow minded as this guy.

Mr Hayman

C.Peters said at November 25, 2012 4:12 AM:

The tech will be availleble in our near future I believe. Leaving our Solar system could that be possible without harming our body's. Change in Magnetic field Exiting on Entry force from either end working against each other. Leaving the speed your travelling limited for the time it takes to Exist And Enter new Sytstems.Is this possible or could Existing or Entry Feel no different to Approaching.


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