Ah, I stand corrected. In this case we may not have the heat buildup problem, just the “long time no see!” problem.
Sorta. Once the starship reaches another system, it can unpack. We don’t know precisely what the minimum payload size is, but existing biological examples tell us that it can be very small. What the payload essentially has to be is 3 things :
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Atoms arranged in such a way to provide optimally efficient storage of data. We don’t know what the absolute perfect layout is as of 2015, but conceptually we do know that such a layout exists. You can call the resulting product “molecular memory”.
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Atoms arranged in such a way to provide optimally efficient computation. Essentially, a computer with the logic gates in it the smallest that physics (and the design constraints of having to survive a high radiation interstellar voyage) will allow. Such a theoretical, but very real in a practical sense (as in, if you don’t believe it exists you aren’t a credible scientist) arrangement is called “computronium”.
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Machinery that can build everything used in itself, and thus bootstrap you back to the infrastructure used to create starships. The most compact such machinery probably looks a lot like biological systems in some ways.
A really optimal payload probably combines the functions of #1-3 in a single integrated blob of machinery. The structural supports for the machinery in #3 happen to also act like memory and computation, etc. The ship would probably need to be constantly breaking down components of itself and remaking them from the constituent elements during the entire voyage, keeping itself in tip top shape Ship of Thebes style. This is also how you could voyage for centuries and expect to have a working engine for the deceleration burn. (and expect to run your antimatter engine for probably decades)
Anyways, once it arrives in system, it finds a small rock somewhere - I don’t think the physics of stellar formation are such that a star exists without some small rocks with all the necessary elements can’t be found. It lands on the rock Phillae style and begins digesting.
The only currently demonstrated way to produce antimatter in any quantities are particle collision into a target or stimulated β[SUP]+[/SUP] decay at an energy conversion efficiency on the order of 10[SUP]-7[/SUP]. The energy required per positron would be about 0.8 µJ, or roughtly 460 million PJ/mg. To do this by stimulated pair production would require a laser operating in the 240 000 PHz range (half of the energy from which would be wasted producing an ordinary electron). Anti-proton and anti-hydrogen production is even more costly, and you can’t produce composite bosons via pair production because they aren’t elementary particles. Generating bulk amounts of antimatter via seperation during “spontanous pair production” would require a fundmental retooling of quantum mechanics. And on top of all of this, actually getting useful thrust directly from antimatter reactions would require some means of capturing and directing the output, which we could do with exotic charged particles like pions and muons provided we could do so before they decay, but no known material is capable of specular reflection of high energy gamma radiation. The radiation could be absorbed by some other propellant material to thermalize it but then it is just returning to a thermal rocket, albeit a massively inefficient one.
I don’t know what you mean by “scanning and converting” brains, but both the complexity of the mammalian brain and our poor understanding of the highly interconnected and recursive processes within it are vastly beyond current or proposed ability to simulate on even the most powerful supercomputers. We can’t even accurately simulate the enfolding of single complex proteins, much less the complex interactions of neurtransmitter-neuroreceptor or the development of dendrite structures in memory and learning. The state of the art in computational neuroscience in modeling anything like actual brain activities are crude simulations of portions of the ‘brain’ of Aplysiomorphs (sea hares). Other models rely upon the use of neural correlates and similar methods to abstract brain behavior rather than direct phenomenological representation. “Copying” or simulating a human brain directly is as much science fiction at this point as warp drives and wormholes; it may be theoretically possible, but we don’t even have enough knowledge to even speculate how we could implement it in practice.
Using a coolant fluid to carry away waste heat is certainly physically possible, but it then increases the mass of consumables. On a space vehicle with a limited mission duration, or in a space habitat that could be replunished by materials from in-situ space resources, but this is not remotely practical for a vessel that would have to operate for centuries or millenia (or at very high specific power output for years) without replenishment.
Are there any other “glaring errors” you want to follow around spitting at me like a dyspeptic cat?
Stranger
Yeah. You lack any understanding of neuroscience, please don’t post further unless you read a book on it. You don’t need to understand protein folding to emulate a brain, and hardware emulation using chips intended for the task is enormously more efficient than current efforts.
As for droplet radiators : read up on them before posting as well. Note the droplets don’t have to be liquids, it’s just easier that way. Losses are minimal to none, depending on design.
Moderator Note
You have a tendency to post things like this that are extremely condescending and insulting. You need to stop doing it in GQ now. If you tell someone not to post again about something because you think they don’t understand the topic, you will receive a warning for it.
If you want to insult what you think is someone’s lack of understanding on a topic, do so in the Pit.
I’m sorry for insulting Stranger. However, he’s not the first one to throw stones. I think calling me a dyspeptic cat is in fact more “condescending and insulting” than calling out someone for :
(a) insisting you have to understand biology perfectly to emulate neuroscience to sufficient fidelity for sentience (when real world results show this is not the case)
(b) insisting a droplet radiator system must involve losing mass as vapor. It is quite obvious that the “droplets” can be tiny solid tungsten beads or some other substance, it simply is not immediately apparent how to handle such a substance (and transfer the very heat you are trying to radiate to it) with known engineering.
In my opinion, he richly deserved my response. I should have explained in more detail why he is wrong instead of just telling him to go read a book.
I understand that there’s been some back and forth here and that Stranger On A Train’s dyspeptic cat comment wasn’t entirely innocent either. This isn’t the first time that you’ve told someone not to post further on a topic though, and that needs to stop.
And yes, you should have explained in detail why you thought he was wrong. Attack the post, not the poster. That’s the rule around here.
What do fluid cooling systems have to do with neuroscience, anyway? I wouldn’t think that any expertise at all in neuroscience would be needed to discuss fluid cooling systems.
Did people know the physical reason for the sound being created? When did a sonic boom get doped out?