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The Challenge of Relativistic Spaceflight

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Re: The Challenge of Relativistic Spaceflight

#71

Post by kjs3 »

Tloewald wrote: post #69
Houshalter wrote: post #63

Earlier quoted context omitted.

Name one machine that's designed to work for over 100 years. Many of NASA's spacecraft have survived well beyond their intended death dates, because they were constructed so well, and because space is cold, static, and good at preserving things.

There are plenty of simple, well-made machines designed to work indefinitely -- e.g. doorknobs, window assemblies. Even simple, robust, well-maintained machinery tends not to last a very long time. There's a stone bench somewhere that Thomas Jefferson supposedly used to sit on that has become curved over time.

I live in a mostly original (at the time I purchased it) 1950s home, and I can assure you that doorknobs and window assemblies do not last indefinitely.

Re: The Challenge of Relativistic Spaceflight

#73

Post by jessedhillon »

darkmighty wrote: post #67
cousin_it wrote: post #62

Earlier quoted context omitted.

I think you have "fantastic" and "real world" backwards. The Blue Brain project is planned to have an uploaded rat brain this year (2014). Uploading human minds is very likely to be closer than capturing the whole energy output of the Sun, which is discussed in the OP. Though uploading will likely cause so many changes that space exploration will seem insignificant in comparison, see Robin Hanson's "The crack of a fu…

The Blue Brain project will have a rat brain model . It reproduces some of the responses you'd expect from a real. That's orders of magnitude of technical progress away from what an upload would require. We don't even know for sure if it's physically possible to perform an upload (due to quantum mechanics), much less have a device which can come close to measure a significant part of the quantum state of a working br…

Can you point to some introductory reading about the quantum mechanical effects at work in the brain? I've read The Emperor's New Mind but was left with the impression that it was more conjecture than research.

Re: The Challenge of Relativistic Spaceflight

#74

Post by ForHackernews »

kjs3 wrote: post #70
ForHackernews wrote: post #57

Earlier quoted context omitted.

\ shrug\ It's all sci-fi tech anyway. Artificial wombs probably aren't that far off: http://www.popsci.com/scitech/article/2005-08/artificial-wom... There's a clear demand for advanced reproductive technology, and it would offer the secondary advantage of neatly sidestepping the current abortion debate.

You're missing my point (which I suppose I really didn't make, so my bad). A child raise by machines is likely to be one seriously emotionally messed up child.

Oh, yeah, probably. Still, there wouldn't be any frame of reference. Maybe the first generation of kids would all be weird and emotionally unstable by our standards, but they're be "normal" for Alpha Centaurians (or whatever)

Re: The Challenge of Relativistic Spaceflight

#75

Post by oakwhiz »

scarmig wrote: post #47
JoshTriplett wrote: post #29

Earlier quoted context omitted.

While the speed of light is the same, relativity also has a lot to say about accelerating reference frames. That said, if you were accelerating fast enough to affect the behavior of a CPU, you'd be experiencing G-forces comparable to the tidal forces of a black hole; computation would be the least of your problems.

Hmm, suggests a vaguely related question to my mind. Generally speaking, do black holes have any implications for computations? E.g. does having a black hole at your disposal let you solve any problems you wouldn't be able to otherwise?

What you are describing is a form of hypercomputation. It is not yet known whether hypercomputation is even really a "thing." A hypercomputer, if it existed, would be able to solve the halting problem.

http://en.wikipedia.org/wiki/Hypercomputation http://en.wikipedia.org/wiki/Malament-Hogarth_spacetime

Re: The Challenge of Relativistic Spaceflight

#76

Post by wazoox »

cousin_it wrote: post #62
snowwrestler wrote: post #32

Earlier quoted context omitted.

If we're going to stipulate fantastic concepts like "uploaded minds" then let's just invent a hyperspace engine too and solve all the problems at once. In the real world, we want to send human bodies because that's what human minds are. Cartesian duality is a religious/philosophical concept for which no scientific basis has yet been found.

I think you have "fantastic" and "real world" backwards. The Blue Brain project is planned to have an uploaded rat brain this year (2014). Uploading human minds is very likely to be closer than capturing the whole energy output of the Sun, which is discussed in the OP. Though uploading will likely cause so many changes that space exploration will seem insignificant in comparison, see Robin Hanson's "The crack of a fu…

I'm afraid you fell for the hype. We're still unable to understand the puny brain of Caenorhabditis elegans, or how the bees achieve all that they can do with as little a brain. Rat brain is several orders of magnitude harder.

Re: The Challenge of Relativistic Spaceflight

#77

Post by hcarvalhoalves »

Houshalter wrote: post #58
ryandrake wrote: post #24

TL;DR: Chemical propulsion is a dead end. But, the alternatives require matter/energy of ridiculous scale (hundreds of times the power output of human civilization, launching hundreds of millions of tons of matter into orbit). We're not going anywhere, any time soon.

That's not true. Project Orion would have been propelled by detonating small nuclear bombs, which have huge amounts of energy. It would be absurdly expensive, but technically feasible today.

I believe they never figured out the necessary shock absorbers, so manned flight wouldn't be feasible today.

Re: The Challenge of Relativistic Spaceflight

#78

Post by snowwrestler »

Tloewald wrote: post #36
snowwrestler wrote: post #32

Earlier quoted context omitted.

If we're going to stipulate fantastic concepts like "uploaded minds" then let's just invent a hyperspace engine too and solve all the problems at once. In the real world, we want to send human bodies because that's what human minds are. Cartesian duality is a religious/philosophical concept for which no scientific basis has yet been found.

Uploaded minds is hardly an argument depending on cartesian duality. Arguing that there's something irreproducible about the human brain is quite close to cartesian duality. I am not arguing that uploading minds is any more feasible than a generation ship, but it is at least more plausible than hyperdrive -- based on what we think we know right now.

Human brains are no more difficult to exactly reproduce than any other piece of matter: extremely difficult. The best we've done to date is a few previously entangled particles.

Edit to add: what I'm talking about here is quantum teleportation of the matter of the brain.

Typically when people talk about "uploading a mind" they mean that the mind is software running on the hardware of the brain--like Windows running on a PC. I'm not aware of any scientific evidence that the mind and brain can be considered separately in that way.

Re: The Challenge of Relativistic Spaceflight

#79

Post by GFK_of_xmaspast »

Houshalter wrote: post #58
ryandrake wrote: post #24

TL;DR: Chemical propulsion is a dead end. But, the alternatives require matter/energy of ridiculous scale (hundreds of times the power output of human civilization, launching hundreds of millions of tons of matter into orbit). We're not going anywhere, any time soon.

That's not true. Project Orion would have been propelled by detonating small nuclear bombs, which have huge amounts of energy. It would be absurdly expensive, but technically feasible today.

Personally I would prefer alternatives that didn't involve "detonating a shit ton of nuclear weapons in the atmosphere" or "sending lots and lots of uranium and/or plutonium into orbit on rockets".

Re: The Challenge of Relativistic Spaceflight

#80

Post by GFK_of_xmaspast »

Tloewald wrote: post #69
Houshalter wrote: post #63

Earlier quoted context omitted.

Name one machine that's designed to work for over 100 years. Many of NASA's spacecraft have survived well beyond their intended death dates, because they were constructed so well, and because space is cold, static, and good at preserving things.

There are plenty of simple, well-made machines designed to work indefinitely -- e.g. doorknobs, window assemblies. Even simple, robust, well-maintained machinery tends not to last a very long time. There's a stone bench somewhere that Thomas Jefferson supposedly used to sit on that has become curved over time.

Are you seriously going with "a stone bench" as your example of the durability of "robust well-maintained machinery".
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