The distance isn’t just a challenge for traversal, so is the time. How do you make a probe that will remain functional in the harsh environment of space for a period of millions, or billions of years?
I’m not doubting that that’s a big problem for us, but in this context it would belong to the set of “easy” problems.
Remember, the average species that is more advanced than humans is likely to be much more advanced than us; millions of years technological equivalent, or thousands of times of all of human history combined.
So, we really need to think of problems that are fundamental limitations of physics (and even then, some of the things we think of as insurmountable are likely to be more nuanced with a fuller understanding). Pointing out things that would be big engineering challenges for humans right now is not going to cut it.
Humans have already made probes that can survive the harsh environment of space for probably centuries at least.
Humans have already made code and circuits that can survive a certain number of mutations / damage and continue functioning or even repair the damage (in the case of code).
It’s a bit of a stretch imagining that for an advanced species that scaling this up would be insurmountable, or to be frank, even non-trivial, millions of years worth of technological improvement in the future.
I don’t find the argument that they’d be more advanced to be very satisfying. It’s handwaving. They might be more advanced, but physics and chemistry is the same for them. The difference between a machine that can function for decades vs one that can function for millions or billions of years is not a simple scaling-up thing. Over those sorts of timescales, things just fall apart because of diffusion and other tiny influences that are just irrelevant in durations of a few dozen years.
Most importantly, something would have to motivate them to do the R&D for eternal machines, at the same time as probably, just like us, not needing such things for any other purpose.
Why aren’t we investing serious effort in designing probes that will last forever and explore the galaxy?
No it’s not handwaving.
Either advanced ETs exist, or they don’t.
If they don’t, then it’s irrelevant to talk about the difficulty of making such probes.
If they do, then, given the universe’s age, it incredibly unlikely that they would merely be a little more advanced than us. Even if there are limits on how soon advanced life could appear (e.g. requiring a Pop I star) the window is still going to be billions of years wide, and chances are they would be at least tens of millions of years ahead of us.
Now of course, we don’t get to say “Advanced aliens, therefore magic”, and frankly, that was very clear in my previous post. I said specifically that they are of course limited by physics. However building damage resistant or self-repairing systems is not something contrary to the laws of physics; we’ve done this, life does this, and there’s no obvious reason why a machine specifically designed for the purpose could not do this over millions of years.
Engineering issues with building (sub-FTL) spacecraft is not a good suggestion for why we haven’t seen aliens.
Barely two centuries ago our most advanced transportation technology was a horse and buggy.
It’s still prohibitively expensive for humans to launch probes, but it’s got a hell of a lot cheaper in my lifetime, and could become trivial if we could build them in space. And what is my lifetime as a fraction of millions of years?
Maybe our understanding of chemistry and physics is really elementary.
How will a self-repairing machine be powered, in the void of interstellar space, for millions or billions of years?
A billion quadloos says you can’t prove that.
Firstly of course you only need whatever power required to repair / restore radiation damage, assuming that radiation shielding cannot simply be improved to the point that this is a non issue.
Secondly, why would we need power for millions or billions of years? A probe can travel from star to star in a tiny fraction of that, even at speeds far below c, where there’s plenty of energy to be gathered.
We can’t prove anything regarding aliens until we see them. However, I gave my reasoning, what reasoning would support the hypothesis that an ET that was more advanced than us would typically only be a little more advanced than us?
What timescales are you assuming? If you leave repair until you arrive, what happens if the power-gathering equipment is one of the things that needs repairing? (Which seems likely if it’s on the outside, ready to gather power)
I don’t need to assume anything. For the purpose of the Fermi paradox, it’s only sufficient to say that we don’t know of any reason why it would not be possible to construct an interstellar probe.
If you think otherwise, and think you’ve proven it impossible, that’s fantastic, I’d be interested to see the proof. As would most scientists, who don’t typically include “harshness of space” as even a candidate explanation for the Fermi paradox.
At mere Voyager speeds, we are talking more in the tens of thousands to hundreds of thousands of years. And there is no reason why a more advanced technology can’t easily bump up those speeds by an order of magnitude or more.
There are many ways to power such a thing, not just solar. You could have a nuclear reactor, thorium based, just slowly sipping at the fuel until it needs to ramp up power.
I’m never quite sure how seriously to take the demands that we use our knowledge and technology to show the designs of something that would be built with far greater knowledge and technology before it can be accepted as possible.
If we can envision it, then it needs to be shown why it is impossible, not just hard, to do, to explain why no one else would have done so. That probably rules out things like FTL, as we are fairly sure that’s impossible, but that doesn’t rule out robust engineering.
Go back 30 years, and explain why we could never fly a helicopter on Mars. Demand a proven design and mission plan before you accept that it is possible. That’s kinda the same thing, except that we are talking about thousands of years or more in the future.
IIRC, Michael Crichton in The Andromeda Strain suggested that the most probable forms of alien life to come to earth (or terrestrial life to visit exoplanets) were bacteria.
You’re suggesting I prove a negative?
Nope. “Give me any reason to suppose that that’s impossible” is not equal to “Prove a negative”.
Bear in mind that there are projects like Starshot considered feasible by many astrophysicists. If what they are doing is impossible, you must go tell them, share your wisdom.
Tucker Carlson believes in UFOs.
Game, set, and match.
But we can still build extremely accurate and precise tools and instruments, including nanometer-scale microchips, atomic clocks, and interplanetary spacecraft? Not bloody likely.
https://chem.tufts.edu/answersinscience/relativityofwrong.htm
Not sure your point. Elementary doesn’t mean wrong, elementary means that there is still far more to be learned.
The Asimov essay that you cited even proclaims this at the end.
And our knowledge of chemistry and physics is far from complete. That we have done as much as we have with what we know is quite an accomplishment, but it doesn’t say anything of what we can do if our understanding become more complete.
If you were asked if we could fly a helicopter on Mars 30 years ago, I’m sure you could come up with a whole list of reasons why we couldn’t or wouldn’t. I’m not sure that it’s quite right to limit what we can accomplish in the next hundred or thousand years based on what we believe to be the heights of our current tech.
“Aliens stole my brain!”
All of that might be elementary on a bigger scale.
Elementary means a simple, crude outline.