The Space Thread!

SpitfireMK461 said:
I read about that idea last year. I'm not at all educated enough to actually comment on the practicality of it, but the theory sounds perfectly plausible. It really is exciting that this is real research, now.
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It's not.

People are overblowing this story. It is a small "let's see if..." project that one dude worked on for a little while out of curiosity. He was able to tweak the math so that the efficiency of this hypothetical drive is much better. Which is cool.

But people took and ran with this story because they look at the numbers and to them it seems plausible, but it's not.

In order for the drive to work, it requires exotic matter that has yet to be observed or even hypothetically vindicated by physics. The matter required exhibits negative mass, in effect a pushing force instead of a sucking one. The existence of exotic matter is based on the classical idea of a super symmetric universe whereby every state of matter has an opposite state (this isn't true, and it hasn't been since kaon K+ and K- decay rates were observed and documented to be non symmetrical, not to mention the intuitive reasoning that a super symmetric universe is not the reality due to the lack of an even distribution of matter and antimatter in the mature universe). No theory of physics requires this exotic negative mass material to exist, it is simply allowed for if you plug in some strange numbers to your equations. It's not like the Higgs boson, which was literally required to exist for the standard model of particle physics to function.

So if it doesn't exist in nature in any meaningful quantity (which may or may not be true, since we may have yet to find it), we may still be able to make it, just like we make antimatter. Before the Large Hadron Collider was switched over to protons, it was called the LEP - Large Electron Positron - collider. The LEP was the single greatest antimatter creation machine ever made by humans. In the mid-90s it spurred a huge investigation by the US Air Force into the idea of an antimatter bomb. They figured there would suddenly be kilograms of this stuff just lying around. Sounds great, we can just make the exotic matter in the same way using an accelerator.

Turns out, over the entire lifetime of the LEP, it's only ever created enough antimatter to power a light bulb for about a minute. It is hypothesized that an exotic matter particle will take a lot more energy than anything CERN has in order to make one pop into existence. Even then, it would only house a tiny portion of the energy that the accelerator used to get it to appear.

I have read multiple reports on this, and the quantity of exotic matter required by the warp drive seems to vary from 500 kilos to over 700 kilos. Even if we assume that only 500 kilos of exotic matter are required, and even if we were able to make this stuff at perfect energy conversion rates, we would need to expend the equivalent energy of over 503,000 Nagasaki atom bomb explosions to get the matter. In reality that expenditure might be ten times that much or greater, once inefficiency is accounted for.

And even though the loophole in general relativity allows FLT travel via moving space around the reference frame, the reference frame (the crew, the ship, the cargo) still has to end up a certain number of unit lengths of spacetime away from where it started, and whether you bend the fabric of space, or you push the object through it normally, or you build a wormhole to tunnel outside our normal space dimensions, you still need to expend the equivalent energy to get there - no cheating. You can abstract that energy expenditure by using exotic materials, but the costs still crop up - in waste, in containment (imagine the energy required to keep a ship with a passive acceleration device from just rocketing out of drydock on it's own), in slowdown time, and a multitude of ways we probably can't even consider yet. The same issues came up with the idea of an antimatter drive or generator, and the whole vibe was killed to death within a couple years.

I'm normally optimistic about this stuff but exotic matter warp devices have a long, long way to go before it's even remotely plausible. I'm much more excited about actual, tangible new propulsion devices that we can use to go to other systems in the very near future.
 
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Well that's enlightening.

Ion propulsion is only somewhat exciting to me. Yes, they are great compared to what we currently have. They allow us to get around the solar system significantly better, but they aren't a great answer for interstellar travel. Even the best ion engines would require decades to reach Alpha Centauri, and it is hard to call a mission reasonable if it takes a literal lifetime to get anywhere.
 
SpitfireMK461 said:
Ion propulsion is only somewhat exciting to me. Yes, they are great compared to what we currently have. They allow us to get around the solar system significantly better, but they aren't a great answer for interstellar travel. Even the best ion engines would require decades to reach Alpha Centauri, and it is hard to call a mission reasonable if it takes a literal lifetime to get anywhere.
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The first extrasolar missions won't be able to do more than 20 or 30% the speed of light, and won't reach any other systems for 50 or 60 years after launch. It is feasible that we could see data from autonomous rovers from another solar system within our lifetimes. I think that's pretty exciting.
 
MadCat360 said:
The first extrasolar missions won't be able to do more than 20 or 30% the speed of light, and won't reach any other systems for 50 or 60 years after launch. It is feasible that we could see data from autonomous rovers from another solar system within our lifetimes. I think that's pretty exciting.
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Feasible but unlikely. You'd have to send a probe with a transmitter strong enough to send messages over 4.5 lightyears and a power source that will continue for over half a century, so it would likely be a fairly significant vehicle, which means the mission to get it going would be hugely expensive. You'd need to cover the logistics of a mission team that performs and evolves over half a century, likely involving multiple generations of engineers. On top of that, if we wanted to see it in our lifetimes, it would have to start within the next few years and be successful on the first try.

I'd love, more than anything, to see Man reach out across the stars, but unless I live to be exceedingly old, I very much doubt it will happen without significantly faster vehicles.
 
Either we can aim to get there 70-90 years from now using relatively modern technology, or we can wait 150-200 years for a magic engine. I know which one I would put money on as being the favorite among the space community.
 
MadCat360 said:
Either we can aim to get there 70-90 years from now using relatively modern technology, or we can wait 150-200 years for a magic engine. I know which one I would put money on as being the favorite among the space community.
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I'm not saying we shouldn't use what we have. If ion engines are the best we've got, let's use them, but they have obvious limits. They may be the key to our first steps to other stars, but they won't be able to sustain serious exploration attempts. Minor probes, yes, but even just sending one is exponentially more difficult than anything we've so far done. Within our solar system, we can send commands and such to probes to fix problems, correct trajectories, etc. When a probe is lightyears away, it is all on its own. It has to be completely successful on its own. It has to fix problems and make adjustments all on its own. It would have to be 100% perfect when it left Earth and never fail. Transmitting any information back to Earth would be incredibly difficult. Sending photos back, not to mention video, might be nearly impossible without advances in areas like quantum entanglement (which admittedly would fix the aforementioned problems), but that itself could be decades away.

Without FTL information transmission, the only hope for human interstellar exploration with ion engines would be multi-generational colony ships, whole families dedicating their lives to the endeavor. That is a sci-fi fantasy. Technically possible, but requiring resources and funding on an extraordinary scale. It would likely be the biggest and most expensive human undertaking ever.
 
Well, there is 'something' that's pulling the universe apart, making it accelerate instead of slow down like normal physics predicted some time ago, and that 'dark energy' still is unknown and unobserved (just its effects). Wouldn't something causing that need to have negative mass too?
 
SpitfireMK461 said:
I'm not saying we shouldn't use what we have. If ion engines are the best we've got, let's use them, but they have obvious limits. They may be the key to our first steps to other stars, but they won't be able to sustain serious exploration attempts. Minor probes, yes, but even just sending one is exponentially more difficult than anything we've so far done. Within our solar system, we can send commands and such to probes to fix problems, correct trajectories, etc. When a probe is lightyears away, it is all on its own. It has to be completely successful on its own. It has to fix problems and make adjustments all on its own. It would have to be 100% perfect when it left Earth and never fail. Transmitting any information back to Earth would be incredibly difficult. Sending photos back, not to mention video, might be nearly impossible without advances in areas like quantum entanglement (which admittedly would fix the aforementioned problems), but that itself could be decades away.

Without FTL information transmission, the only hope for human interstellar exploration with ion engines would be multi-generational colony ships, whole families dedicating their lives to the endeavor. That is a sci-fi fantasy. Technically possible, but requiring resources and funding on an extraordinary scale. It would likely be the biggest and most expensive human undertaking ever.
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Quantum entanglement has an incredibly low bit rate. You'd really only be able to send morse code with it. But laser communication has a high bit rate and signal strength over distance.

http://www.popularmechanics.com/sci...nasas-experimental-laser-communication-system


As far as AI, we are getting closer and closer to quantum computing, and it may even happen before 2025.

http://phys.org/news/2013-01-qubit-bodes-future-quantum.html

A processor like that would easily accommodate a child-like intelligence program for a remote drone, and an orbital craft with a more powerful processor (possibly human adult-like in intelligence) could handle strategic mission objectives. I mean, we're talking about a machine that can bust a 16-character password in less than a tenth of a second. That would take years for an i7.


mpicco said:
Well, there is 'something' that's pulling the universe apart, making it accelerate instead of slow down like normal physics predicted some time ago, and that 'dark energy' still is unknown and unobserved (just its effects). Wouldn't something causing that need to have negative mass too?
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We don't even know if dark matter is actually matter yet, let alone dark energy. Initial measurements of the cosmic microwave background haven't yet hinted at a large population of negative mass matter. They determine this by triangulating points on the surface of the CMB in order to inspect the meta-curvature of spacetime between here and there, in essence "weighing" the universe. They don't find curvature of significant shape to deduce a lot of negative mass matter in the universe when comparing that shape to the known quantity of bright object residing in our visible galaxies. At the moment it seems the answer doesn't lie in the material composition within the universe, unless exotic matter inexplicably does not radiate or reflect any radiation.
 
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The point of quantum entanglement is to have FTL information transfer. In our case, this would allow an interstellar probe to communicate with Earth in a reasonable time scale. Laser communication has a high bit rate, but it would still take 4.5 years to communicate with Alpha Centauri (not that you could get a laser across that distance to begin with).
 
SpitfireMK461 said:
The point of quantum entanglement is to have FTL information transfer. In our case, this would allow an interstellar probe to communicate with Earth in a reasonable time scale. Laser communication has a high bit rate, but it would still take 4.5 years to communicate with Alpha Centauri (not that you could get a laser across that distance to begin with).
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Lasers are not limited by intervening space if that space does not contain an atmosphere. They are only limited by our ability to project and receive a beam. (Well, practically - cosmic horizon being the ultimate limit.)

In reality, any quantum entanglement communicator we would be able to fit on a starship would not have the bit rate to transmit an image in 5 years. You could use a small one to transmit yes or no updates to mission queries, and then use laser systems to transmit image and maybe audio.
 
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This is happening down the street from where I work.

http://www.nasa.gov/centers/wallops/news/west129.html

WALLOPS ISLAND, VA -- A NASA rocket mission to test technology for gathering science data during future projects is scheduled for launch between 5:30 ? 6:50 p.m. EST, January 29, from the NASA Wallops Flight Facility in Virginia.

During the suborbital flight of the Terrier-Improved Orion sounding rocket, two red-colored lithium vapor trails will occur in space that may be seen throughout the mid-Atlantic region.

Cameras at Wallops and on a NASA aircraft will view the resulting red trails.

Libby West, mission project manager with the NASA Sounding Rocket Program Office at Wallops, said ?This launch is a technology test flight for two upcoming missions. We will be testing two different methods for creating the lithium vapor to determine which configuration is best for observing various science phenomena in space.?

NASA has two missions later this year that will use the lithium trails to assist scientists in observing events in space. The first is scheduled for April in the central Pacific Ocean from Kwajalein Atoll in the Marshall Islands and the second will occur in June at Wallops.

In the technology test launch, two canisters in the rocket?s payload section will contain solid metal lithium rods or chips embedded in a thermite cake. The thermite is ignited and produces heat to vaporize the lithium. The vapor is released in space and can be detected and tracked optically.

During the flight, one vapor trail will occur at approximately 72 miles altitude and the second will occur at around 78 miles altitude.

The lithium combustion process poses no threat to the public during the release in space. When heated, the lithium rods change to lithium vapor and small amounts of lithium oxide. The thermite reaction produces iron and aluminum oxide.

The backup launch days for this project are January 30 through February 1.

The NASA Visitor Center at Wallops will be open on launch day for public viewing of the launch.

The mission will be available live on Ustream beginning at 4:30 p.m. on launch day at: http://www.ustream.com/channel/nasa-wallops

Mission status on launch day can be followed on Twitter and Facebook at:http://www.twitter.com/NASA_Wallops or http://www.facebook.com/NASAWFF

Mission status also is available on the Wallops launch status line at 757-824-2050.
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SpitfireMK461 said:
The point of quantum entanglement is to have FTL information transfer. In our case, this would allow an interstellar probe to communicate with Earth in a reasonable time scale. Laser communication has a high bit rate, but it would still take 4.5 years to communicate with Alpha Centauri (not that you could get a laser across that distance to begin with).
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I thought you couldn't transmit information using quantum entanglement?
 
chaos386 said:
I thought you couldn't transmit information using quantum entanglement?
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Sure you can. If you have a photon (or other particle) in an isolated environment with an entangled pair somewhere else, if the guy on the other end manipulates the polarization of his particle, the polarization on your particle will change too. You can interpret this change as a bit.

The problem is the quantum states must be calibrated and agreed upon by both ends via traditional communication. If you don't continually observe your particle(s), they will drift out of calibration and you will get a ton of errors when you try to decode. So any quantum communicator would still be limited, in part, by light-speed communication methods used for calibration.
 
MadCat360 said:
if the guy on the other end manipulates the polarization of his particle
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When you say "manipulates", do you mean he observes his particle and measures the (random) polarization, or forces his measurement to be a polarization of his choosing? As far as I understand things, the latter is impossible, and is the crux of why two particles can feel each other's effect instantaneously, yet you cannot use this to transmit any information.
 
chaos386 said:
When you say "manipulates", do you mean he observes his particle and measures the (random) polarization, or forces his measurement to be a polarization of his choosing? As far as I understand things, the latter is impossible, and is the crux of why two particles can feel each other's effect instantaneously, yet you cannot use this to transmit any information.
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He measures the information and the sender at the same time. You need 3 particles - the info particle (the one you want to copy, which you can arrange to be of a certain state), and the two entangled particles, which can't be measured until you're ready to send. You measure the difference between the info particle and the local sender particle, then beam that difference to the receiver via laser or radio or a phone call or email or whatever. The receiver interprets the difference to change his particle to the measured state of the info particle.

That's why quantum teleportation/communication is limited by calibration times. And now that I think about it I don't know why I suggested the space craft used a combination of the two methods, because you'd need to beam the calibration information before the message could be assembled anyway, so a quantum communicator would be kinda pointless if you already had a laser system. This shit is confusing and I'm not that smart.
 
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MadCat360 said:
He measures the information and the sender at the same time. You need 3 particles - the info particle (the one you want to copy, which you can arrange to be of a certain state), and the two entangled particles, which can't be measured until you're ready to send. You measure the difference between the info particle and the local sender particle, then beam that difference to the receiver via laser or radio or a phone call or email or whatever. The receiver interprets the difference to change his particle to the measured state of the info particle.
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It sounds like the information is transmitted by the laser/radio, not the particles. I'm not even sure why the entangled particles are necessary in your example. :?
 
chaos386 said:
It sounds like the information is transmitted by the laser/radio, not the particles. I'm not even sure why the entangled particles are necessary in your example. :?
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Because the receiver particle could be in one of 4 possible states and you need to measure the sender particle to know what opposite state the receiver particle occupies. You can then make the necessary adjustment to make the receiver particle match the info particle.
 
I thought I had watched a video by Michio Kaku saying why particle entanglement can't be used to send messages like that...

Oh here it is

 
mpicco said:
I thought I had watched a video by Michio Kaku saying why particle entanglement can't be used to send messages like that...

Oh here it is

http://www.youtube.com/watch?v=QErwOK3S5IE
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Right, it's random because the sender and the receiver particles could be in any one of the four possible states, so you need to measure one - and send that data to the other end via external means - to deduce the other. You cannot both have entangled particles *and* know their configurations. Knowing their configurations precludes entanglement because entanglement collapses with measurement.

There has been some work on a quantum communicator system that does not require entanglement nor calibration data-sending, but I really don't know anything about it.
 
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