Interstellar travel; possible or not?

Great Debates
21

I would like more than anyone to see mankind flourish throughout the universe and see everything there is to see. And it may in fact happen.

But you are making a fundamental error by trying to extrapolate the curve of advancement we see today as continuing into the future. People were doing that in the 1950’s, and coming to the conclusion that we’d have faster than light travel by 2010. Unfortunately, the curve of speed increase flattened out in the 1970’s. The fastest thing mankind has ever launched was over 20 years ago.

Who would have guessed that 34 years after men walked on the moon, and 25 years after we already had a manned spacestation and had designed the shuttle, that we’d still be flying the shuttle, and all we’d be doing is flying to a slightly bigger station? And that we’d be farther from being able to get back to the moon than we were in 1960? In 1975 space enthusiasts were sure that by 2010 we’d have colonies in lagrange orbits with tens of thousands of people living in them. In reality, we just scaled down the space station crew from seven people to three.

The thing is, we have advanced very quickly, but are now approaching some fundamental physical limits. Perhaps they can be overcome, perhaps not. But it would be foolish to assume that we can and proceed from that assumption.

Here’s what I think are the likely near and medium term futures for mankind in space:

PESSIMISTIC SCENARIO: Funding for NASA is cut. Shuttle missions are cancelled. That means the end of the NGST and other large space telescopes. The ISS is shut down. NASA resumes a scaled back planetary science program using current technology. For the next twenty years, we’ll see a handful of flights to other planets. Automation gets better, so these probes learn quite a bit. A new manned program, based around a next-generation shuttle, starts up in 5-10 years, and we get back to where we are today except with lower cost and more ability in about 20 years.

LIKELY SCENARIO: The Bush administration appears to be truly enthused about space. Last week we heard that the new NASA budget was going to include enhanced funding for a new fleet of space planes and a new nuclear rocket. If that attitude remains, I think we’ll see the funds going to supporting and flying Columbia diverted to the new spaceplane initiative. A new, cheaper space plane will be flying by 2010. In addition, the nuclear rocket program brings the outer solar system as close as Mars, and Mars within a couple of months travel time.

Under this scenario, there will be major, vastly more capable robotic missions to Jupiter, Saturn, and Neptune within the next 20 years. There will be telescopes launched in that time frame that can image planets around other stars. Man will land on Mars within 20 years. But we won’t see humans exploring the outer planets in our lifetimes, unless you’re really young or we live a lot longer.

HIGHLY OPTIMISTIC SCENARIO: Space Exploration becomes a national priority, being funded to the same levels as things like health care, welfare, and other major domestic programs. That would mean NASA’s budget would at least quadruple. Under this scenario, we could establish a permanent base on the moon within 20 years, a permanent base on Mars within 50 years, and have manned expeditions to the outer planets in the same time frame. We might even see rudimentary exploitation of space by asteroid mining or water mining on the moon in the same time frame.

In the meantime, we would be launching arrays of telescopes of increasing resolution, to the point where within 50 years we would be able to look at planets around other stars and see evidence of intelligent construction. We would be able to see anything in the entire universe, and be able to closely inspect the oldest things in the universe.

Even under the highly optimistic scenario, we won’t even have a good idea of where the earthlike planets are for maybe 30 or 40 years. If we decided to launch a probe to one of them, it would almost certainly be unmanned. The difficulty of sending a human on a multi-decade mission would be enormous compared to the cost of sending an unmanned probe, and the risks of sending a human that far would be unreasonable.

22

To comment on some of Scott’s points:

  1. I agree. Technology Is progressing lightning fast, and is going to get faster, unless life on earth ends (a very real possibility). I’m betting Artificial Intelligence is going to take us to a whole new level in just a few decades.

  2. I’m not sure we can assume that the galaxy is bursting with life. It is a very real possibility that mankind is a freak accident. On the other hand, maybe life is common, but after they reach technological bursting point they trascend dimensions and leave this universe. That would explain why they haven’t landed at the white house lawn yet.

  3. Super-c travel may never be possible. Tech progress alone can’t break a physical law of nature. It can find ways around it though.

  4. I have a question about this one: If you travel near the speed of light, and time slows down relative to your point of origin (earth), does that mean that you perceive your trip to be shorter than it really is? Putting it this way: If I travel at 0.99c to alfa centauri (40 light years I think). Will I perceive the trip to be any shorter than 40 years?

Peace

23

Best statement in this thread.

I have no idea how it would happen. But I would say that everyone who said “no way, it’ll never happen” needs to balance their intake of science with a little bit of history.

You’ve all heard the story of 19th-century patent office chief who thought it a good idea to shut down the patent office because there was nothing left to invent. Even Einstein (which, if I may be so bold, is far more intelligent than anyone of us on this board) spent considerable energy and time arguing with Neils Bohr on the merits of Quantum Theory.

I was going to compose a long list of scientists being short-sighted on one issue or another. But that isn’t necessary. You can look at nearly any scientist of the past and find them to devoutly deny something modern scientist now know as fact, or at least as sound theory.

How silly they all are! How could they be so ignorant? Of course, they aren’t foolish at all. They took everything thus far learned and accepted by science and made an educated statement. And they were wrong.

In fact, the prevailing science of the day, quantum mechanics, is completely counterintuitive to human thought. In his book, "The God Particle, Leon Lederman said that it takes a graduate student of physics into his/her 2nd or 3rd year to develop the proper thought pattern required for an intuitive image of quantum mechanics.
What does history have to offer this debate? Only the historical fact that much of what science reveals 100+ years from now would be flatly denied today. I wouldn’t dare pretend to know what we will and will not be capable of 100, 200, or 500 years from now. In fact, I don’t have a guess. But History tells me to rule out one answer:“never”.

24

I guess some of us older dopers (I’m 39) are pessimistic because we grew up seeing major advances in the space program almost weekly, and have seen that pace of innovation slow to a crawl.

I was in grade 1 when Apollo 11 landed on the moon. My school experience involved seeing a number of moon landings, a Mars lander, a major probe to Jupiter, Apoll-Soyuz, and Skylab. The Shuttle was being developed, and was named after our favorite spaceship on Star Trek. O’Niell wrote ‘Cities in Space’, and NASA was talking about a permanent moon colony and a mission to Mars by 1990. There were going to be 500 shuttle launches a year.

Now here we are 35 years later, and in that time we’ve landed one more (smaller) lander on Mars, blown up two shuttles, scaled back our grand space station to be little more than Skylab was, and now we’re talking about a Mars mission maybe in 20 years.

I gave up on NASA as our saviour twenty years ago. I figured it had become a bloated government agency that was more interested in protecting turf and maintaining budgets than advancing man in space. So I pinned all my hopes on private space ventures.

But where are they? It’s not like people haven’t been trying. There have been numerous private space ventures that have blown through hundreds of millions of dollars. None of them have achieved even what the Mercury program managed. Not even close.

I think pessimism about the space program is entirely warranted.

25

I call it the Disco Stu Fallacy.

26

Yes.

27

Correction: four lightyears to A-Kent/Proxima. And yes, the apparent elapsed time from the POV of you the traveller will be shorted. A quick back-of-envelope gives me an apparent time of something like 6 months and change of “ship apparent time”, while 4.04 years elapse on earth.

28

To expand on il Topo’s post, it WILL be shorter than 40 years… for you and those with you. Our concept of time is merely an invention with a function that ONLY operates on our planet. Time only exists because we decided to measure certain things and make it all work (semi)cleanly. For your cite on this; if we didn’t expand our ‘system’ of time with the use of leap years, eventually summer wouldn’t be summer anymore. At least not the summer most of us think of.

As for my opinion on the main threading, I think we (or whoever we become as a species) will get out there eventually…

If we don’t kill eachother first.

29

Your biggest problem would not be the apparent duration of the trip, but clening up the mess in the cockpit; how do you propose to accelerate to 0.99c without spreading the crew thinly across the back wall?

Point taken, but the fact that, at age 4, I thought five plus five was six and that now, at age 35, I believe it to be ten, doesn’t mean that when I’m 65, I’ll laugh about how naive I was thinking five plus five equals ten.

Everyone who says “future technology will quite likely solve all the problems we now see as insurmountable, it’s just a matter of time” needs to balance their optimism with a reading of Dr Seuss’ If I Ran The Circus

30

Tell me… what would happen if we reversed the direction of the Earth’s spin?

31

Actually scratch that; I thought you were saying that the passage of time is caused by our measuring it.

32

Well, I can think of a whole lot of ways to accelerate without smearing people. The problem is, most of them are science fiction gibberish. They describe a situation fairly well, but nobody really knows how to do it.

Stargates, hyperdrive, even the strange concept of warping and encapsulating a craft in space so that what is experienced inside is not the same as is experienced outside.

They’re all pretty impossible, but that doesn’t mean someone won’t figure something out.

33

“how do you propose to accelerate to 0.99c without spreading the crew thinly across the back wall?”

Umm, slowly? It’s the rate of acceleration thats the problem not the end speed(AFAIK)

34

Well… according to precrisis superman we’d go back in time ;p

nongeek answer: probably worldwide disaster and a nifty madmax future. (GRR, still geeky)

35

Well, how about that famous lightbulb that has been shining since 1901? If we can make a product that should only last 1000 hours last over 100 years by not cutting corners and building it right the first time, then why would you think that ANYTHING that we have the technology to build would be any different? I think that you are cynical due to the inferiority of consumer products that are made as such to ensure that we buy more. We could do it. As long as money didnt get in the way…

36

Yes… and on a trip of four light years, is it possible to accelerate to 0.99c before you get halfway there? (without killing the crew, or for that matter, making them seriously uncomfortable; 4G is fine in short bursts, but months and years of it would be nasty)

37

I say halfway there because of course you have to decelerate at a reasonable rate as you approach the destination.

38

Well, it’s not 100 years, but Voyager 1 and 2 are both still going strong, 25 years after launch, and are expected to continue returning useful data for at least another 20 years.

We have already launched interstellar probes - they’re just really slow. Voyager 2, for example, is heading towards Sirius, and will pass within 4.3 lightyears of it in only 296,000 years. Wake me up for the big event.

39

Mangetout:
It would take considerable time – and power. May not be worth it for Proxima, but could be for really long distances IF it were feasible to build such a vessel. (BTW, while at .99c, you’d be unable to see where you’re going, due to massive blue-shift)

If it were NOT for relativistic effects, that is, if you could just newtonianly accelerate to 296,000 Km/s, it’d take about a year at 1 G acceleration . Problem is, of course, you start running into significant relativistic effects as soon as V[sup]2[/sup]/c[sup]2[/sup] begins becoming a significant fraction itself, causing your mass to increase and the energy demand to shoot up. So travels of single-digit LY distances under this model would be quite uneconomical.

40

Actually, blue shift is another complication that I hadn’t thought of; would radiation at shortened wavelengths be another thing to be shielded against?