That said, we definitely don't have the means to 3D print even relatively simple tissues, last I checked we are still limited to structures thin enough to be kept alive by oxygen diffusion.
One of my open questions on this topic is: given we can cryopreserve small tissue without the freezing-damage problem, why can't we do a repeated process of:
1. cell culture tissue sheets that are ~1mm (or whatever) thick
2. cryopreserve each sheet
3. then assemble those sheets, still frozen
4. then thaw out as per normal procedure for cryopreserved organs
Caveat: I have minimal knowledge of biology, this may be a stupid idea for a whole bunch of reasons I don't even know the names of.
Originally developed in-universe when a bunch of immortal cyborgs got bored on a colonization ship & decided to instruct a precursor probe to print a machine that prints a machine that will print their bodies on site. :)
The engenerator technology is completely safe[1] and can't be misused in any way.
It's easier to see why if you think about Fourier transforms: https://www.youtube.com/watch?v=MBnnXbOM5S4&themeRefresh=1
TLDW: an infinitely long wave does not (cannot) have any definite location, but it does have a definite periodic wavelength; conversely, a single impulse noise (a shockwave from e.g. a bullet or an explosion) has a definite location (in the direction of motion and at any given point in time) but no meaningful wavelength.
The more you constrain the possibility space of one, the looser the other becomes in a physical sense, not just the information you have about it.
Look into Assembly Theory as well: https://en.wikipedia.org/wiki/Assembly_theory They already developed some kind of chemical printer for simple molecules.
It also remains to be seen if you can 'print' a complex biological object, like a human.
There's also no point in talking what can be done today, since such a project would take quite a while, both to assemble and get anywhere close to destination. Just because we cannot do it today doesn't mean it shouldn't be considered as a possible approach since we might get there in 30-50 years, which is nothing for the scales of time we're talking about.
Cryo tech is quite primitive, you are fighting to maintain a structure instead of saving its data and rebuilding it later when tech allows. Imagine 3D printing a benchy and freezing it so it stays "fresh" for 50 years (for some potential use at that time), instead of saving the benchy stl file and printing it in 50 years.
Plans for potential human expansion into our galaxy must include potential tech developments, can't block it to the tech that is available today. The way things are going there's no reason to discard full scan and reassemble of a full human being, in some future. Let alone moving consciousness on other type of more resilient hardware.
https://en.wikipedia.org/wiki/Spin_(physics)
A particle spins on any number of axes
> You need something that harvests particles locally and can receive a stream of data with what to print
You cannot obtain that data because this spin is impossible to measure)
You assume a human is the same as a chair? seems like a stretch
Do you? I already said what I have in mind. particles are not indistinguishable and "scanning" objects without destroying them not possible in this reality
The most likely way to move in the Universe is through something along the lines of von Neumann probes, which can be small machines sent at relativistic speeds across the whole galaxy, setting up these "spawn" points. Even at 10% speed of light it would take 1 million years to get such probes in strategic points to cover most of our galaxy.
What makes an object unique then is the specific configuration of the particles that make up that object. This configuration is a form of information.
Fortunately, we already know how to transmit information at the speed of light; no new physics required. This then reduces the problem to transporting the ‘printer’. No generation ship required. You need something that harvests particles locally and can receive a stream of data with what to print. You can bootstrap this, send a tiny particle harvester/printer that can print a slightly larger printer, etc.