The Challenge of Relativistic Spaceflight • Hacker News Board

Re: The Challenge of Relativistic Spaceflight

#21

Post by josh-wrale » Fri, Mar 07, 2014, 4:04 PM UTC

Master the art of "the transporter" with information being sent via optics. Send a ship out into space. Aboard will be an environment for humans and a big receiver on the side. Send the ship. Wait until it reaches it destination. "Beam" humans to the ship. If boredom ensues, reverse the transmission. Leave the "Stargate" behind. :)

Edit: see quantum entanglement

Edit 2: Thinking aloud about quantum entanglement. I understand that we can slow and stop light by passing it into a Bose-Einstein condensate. Can we thereby suspend two entangled particles, each in its own BEC? That way, we can send our ship out into space, unfreeze light (time?) and proceed to transmit Data (heh).

Edit 3: Transmit, that is: faster than the speed of light. (thinking not) :)

Edit 4: Now, I want to know what happens when a BCE containing stopped light travels at or near the speed the speed of light.. Ah never mind. I'm not a physicist. Cold and fast don't go together easily, either. :)

Edit 5: Do watch: https://www.youtube.com/watch?v=-8Nj2uTZc10

Edit 6: By the way, if Edit 2 is used, no big receiver would be required. Hmm.. Send the quantum receiver to a Class M planet.. Skip the on-ship environment. Terraform to taste.

Re: The Challenge of Relativistic Spaceflight

#22

Post by jp555 » Fri, Mar 07, 2014, 4:05 PM UTC

DennisP wrote: post #18

jp555 wrote: post #15

Earlier quoted context omitted.

> (remember technological progress is exponential not linear) No it is not. For example, airliners fly about as fast as they did a generation ago, and if you buy a desktop computer today it won't be noticeably faster than the ~3 year-old one you're using now. Do you really think the next TV you'll buy will be exponentially bigger than the one you have today? Prepare to be disappointed. warp-engine would require FTL t…

It's not quite valid anymore to say warp drive is flat impossible, given all the theoretical work on the Alcubierre drive. Whether it will ever actually be practical is still a big unknown.

you mean the drive that if it were used it would annihilate your destination in a immense-burst of gamma energy? Not to mention we have no idea how to effectively modify space-time. It is interesting, but the drive is basically "if we had MAGIC, we could do this".

FTL is also exactly the same as time-travel. If you could travel 25,000 light-years in an instant, you could turn a BIG telescope back at earth from your ship and watch early humans hunting mammoths.

Re: The Challenge of Relativistic Spaceflight

#23

Post by asgard1024 » Fri, Mar 07, 2014, 4:06 PM UTC

One challenge to relativistic spaceflight is computing. If you put a CPU into a vehicle, which goes close to speed of light, it may not work properly, because the energy pulses in the device will become unsynchronized when going in different directions.

Re: The Challenge of Relativistic Spaceflight

#24

Post by ryandrake » Fri, Mar 07, 2014, 4:06 PM UTC

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.

Re: The Challenge of Relativistic Spaceflight

#25

Post by cousin_it » Fri, Mar 07, 2014, 4:08 PM UTC

What's the point of these huge generation ships? It's not like there's not enough atoms on other planets. You should send a tiny fast robotic ship, maybe with an uploaded mind if your AI tech isn't good enough. It will mine materials at the destination and build a receiver antenna. Then you can send more uploaded minds by radio, which will arrive at the speed of light with low energy cost.

Another reason why you shouldn't send human bodies in tin cans, or even grow them from eggs on the spot, is that human bodies are not adapted to the conditions in space or at the destination, so they would need an unreasonable amount of life support equipment. If you really want a colony of biological creatures with human minds for some reason, bioengineer the right kind of bodies on the spot and download minds into them.

Re: The Challenge of Relativistic Spaceflight

#26

Post by jp555 » Fri, Mar 07, 2014, 4:08 PM UTC

parksy wrote: post #17

jp555 wrote: post #15

Earlier quoted context omitted.

> (remember technological progress is exponential not linear) No it is not. For example, airliners fly about as fast as they did a generation ago, and if you buy a desktop computer today it won't be noticeably faster than the ~3 year-old one you're using now. Do you really think the next TV you'll buy will be exponentially bigger than the one you have today? Prepare to be disappointed. warp-engine would require FTL t…

How would the ovum develop and be nurtured? Sympathetic alien surrogates? Why not seed more simple lifeforms, such as genetically modified bacteria, upon hundreds of "candidate" planets so that by the time our generation ships arrive there's a good chance some basic terraforming has already occurred.

It was more the thought exercise itself than a practical approach. I just wanted to consider the benefits of very low mass offers to space travel.

Sounds like you're talking about panspermia, which does seem very likely to me as well. http://en.wikipedia.org/wiki/Panspermia

Re: The Challenge of Relativistic Spaceflight

#27

Post by josh-wrale » Fri, Mar 07, 2014, 4:09 PM UTC

asgard1024 wrote: post #23

One challenge to relativistic spaceflight is computing. If you put a CPU into a vehicle, which goes close to speed of light, it may not work properly, because the energy pulses in the device will become unsynchronized when going in different directions.

Cool. I wonder if this holds true for quantum computation, as we theorize it anyway.

Re: The Challenge of Relativistic Spaceflight

#28

Post by ryandrake » Fri, Mar 07, 2014, 4:09 PM UTC

asgard1024 wrote: post #23

One challenge to relativistic spaceflight is computing. If you put a CPU into a vehicle, which goes close to speed of light, it may not work properly, because the energy pulses in the device will become unsynchronized when going in different directions.

Special relativity says the speed of light is the same in all reference frames. In the reference frame of the moving CPU, it would operate correctly.

Re: The Challenge of Relativistic Spaceflight

#29

Post by JoshTriplett » Fri, Mar 07, 2014, 4:14 PM UTC

ryandrake wrote: post #28

asgard1024 wrote: post #23

One challenge to relativistic spaceflight is computing. If you put a CPU into a vehicle, which goes close to speed of light, it may not work properly, because the energy pulses in the device will become unsynchronized when going in different directions.

Special relativity says the speed of light is the same in all reference frames. In the reference frame of the moving CPU, it would operate correctly.

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.

Re: The Challenge of Relativistic Spaceflight

#30

Post by sp332 » Fri, Mar 07, 2014, 4:19 PM UTC

drjesusphd wrote: post #19

Is continually accelerating at 9.8 m/s^2 necessary? Sure, that's what's needed to get off the ground, but it seems excessive for a whole interstellar journey.

Well if you accelerate slower, then you travel slower, then the relativistic effects of your speed are exponentially slower. So it's good to accelerate as quickly as possible.