.99c only dilates time by a factor of 7, so one year of time passed on a vehicle would yield ~7 light years.
Heck, you have to get better than 5 nines to even compress a year into a day, .9999963c, which would take a freakish amount of energy to accelerate a KG to (3.3 × 10^19 J).
Damn, c is too big for traveling with compressed enough time for cheap, yet too small to make communication within the earth be pretty much instantaneous (like getting 1ms roundtrip latency everywhere).
Isn't this a pointless goal anyways since any spaceship we'd have capable of getting to any meaningful percentage of c would get destroyed by any small amounts of matter or gas it bumps into on the way.
That's why we usually end up starting with projectiles instead of ships. Once the drive is ready, someone will take it from you for a few decades to shoot at things.
Impact seems to have a timelined meaning, starting with destruction, then following up with conquering, and exploration coming somewhere before constructive applications at the far end.
As apes we just can't keep holding back till we can build houses or something with it, when we also could just throw that stone at something. Especially before someone else does :)
At these velocities, even a spec of sand is a major hazard. And the distances covered in these shorts of journeys would pretty much guarantee a collision of that sort. (Random search showed a 13mg grain of sand at .999c is equivalent to 1700 tons of TNT).
Even interstellar/stellar wind would have enough molecules of gas to cause some crazy erosion/damage.
In the interstellar medium, matter is primarily in molecular form and reaches number densities of 10^12 molecules (mostly composed of) hydrogen, then helium, oxygen, nitrogen) per cubic meter (1 trillion molecules per cubic meter).[1]
So, what, about a picogram per cubic meter.
If your ship has a cross-sectional area of one square meter, and Alpha Centauri is 40,000,000,000,000 meters away [2] (and you thought it was a long way to the shop if you want a Chiko Roll), you’ll have to manage with 2.62^23 tonnes of mostly hydrogen in the way.
The interstellar medium is also about 1% dust, so about 2.6^21 tonnes of solid matter.
ChatGPT’s math says that a picogram at 0.999c delivers about the energy of a strong human punch. Aside from issues of metal fatigue that wouldn’t seem like the thing to be most concerned with regardless of distance - the effect to me would seem closer to space rain (assuming you could dissipate the heat which seems like the bigger problem).
Dust is a concern but again the typical dust particle size would be about the power of a gun shot of a small caliber rifle. A problem to deal with but a rarer event still. Of course another challenge would be larger dust particles which while improbable are still possible which largely rules out humans in these craft. But that goes without saying since the acceleration to get to that speed would be unlikely something humans could withstand anyway.
Right, but a .357 round delivers roughly the same kinetic energy as nunchucks and particle accelerators are also a thing, which is to say delivery of a human punch to a cross section of area the size of a hydrogen atom is going to have permanent negative impacts to whatever is on the receiving end. I'm imagining the front of the craft ablating at the atomic level and throwing off some wild-ass radiation in the process?
I wonder if it would be possible to push it out of the way with some kind of charged field ahead of the space craft. But even if that's the case it would act like air and cause deceleration.
Could they just send lots of ships on the same path and specifically design them to break apart outward if destroyed, eg spin them at very high rates, to basically sweep the path clean, or would most of the particles in the path only be there because they happened to move into the path momentarily? I don’t know much about the velocities of interstellar particles.
On top of this at 1g it takes ~1 year accelerating to that speed and another year decelerating. So even the nearest star is going to be a multi year subjective journey or a really unpleasant trip.
We do know how to inefficiently create and store antimatter, we don’t have any idea how to cause human hibernation.
To me getting two dozen of orders of magnitude better at something is clearly hard, but that still beats trying to do something we don’t have a clue how to start. For human hibernation step 1 is probably serious genetic engineering and there’s going to be other steps.
Inefficiently in the context of antimatter storage makes every industrial accident since the dawn of time combined seem like a kid spilling their juice.
The inefficiencies around storage are a practical not a safety concern. Once cooled we can contain the particles just fine the issue is only 0.1% get trapped and the apparatus is vastly larger than the mass of antimatter stored.
If you look at particle accelerators, the anti-matter storage is still very much experimental with anti-hydrogen storage holding it for less than 20s at most. We can trap individual particles (e.g. protons) for a long time but things get exponentially more complicated as you increase the size of the system.
Hell, we can't even store hydrogen without leakage issues and with anti-hydrogen any leakage is very bad.
To put that into number that people can understand, to accelerate 1kg of matter to 94% the speed of light you need 1kg of antimatter. That is the equivalent of the tsar bomb. So the storage facility would need to withstand that type of explosion 1000 times over for every kg of antimatter it produces.
World ending doesn't begin to describe what that looks like.
We can freeze and reanimate living things only five or so orders of magnitude removed from humans; if we're just talking hibernation, it's as little as two.
Maybe, but there are mammals that can survive deep hibernation and near-total suspension. In pure biological/biochemical terms I don't see any reason to think we're much more than 100 times more complex than a rodent, or 1000 times more complex than the various fish and amphibian species who can survive their bodies reaching near-zero temperatures.
They've put pigs into suspended animation for an hour or two, I'm not sure what the upper bound is on that or how much further it's possible to go with it. Ditto organ deep-cooling. So while it's not feasible now, it feels like we need "only" 100x or so improvement to make it viable.
The problem with human hibernation is that it is almost impossible to ethically test.
What medical ethics board is going to approve a research project "put healthy experimental subject in coma for 5 years, observe what they are like when they wake up?"
I think this is an example of a technology which, if it is ever developed, is most likely to be developed by some kind of totalitarian regime which has no ethical qualms about human experimentation.
Heinlein story time! Door into Summer
https://en.wikipedia.org/wiki/The_Door_into_Summer
Protagonist signs their life away for a 'cold sleep' that will allow them to wake up many years later. Tech is iffy. They do it because they are desperate, and the interest gained over time should make them rich (doesn't happen of course).
That's not really how hibernation works in mammals, they have to raise their body temperature and come out of hibernation every couple weeks, the leading theory is this is to (ironically) catch up on sleep.
Inducing torpor would have major medical uses in surgical and emergency medicine, it's not just useful for passing the time.
People with incurable diseases or just strange individuals can volunteer for such experiments. After that, if they write about their experiences, it could be featured first on Hacker News.
Heck, you have to get better than 5 nines to even compress a year into a day, .9999963c, which would take a freakish amount of energy to accelerate a KG to (3.3 × 10^19 J).