I believe in aliens from a statistical standpoint.
But I don't believe in interstellar travel at all. I don't think people grasp the distances between stars. The longest distance a human has traveled through space is to the moon. If, for scale, this was about 2 millimeters, then the nearest star would be another 200 kilometers/124 miles away. Here's a great video to illustrate https://www.youtube.com/watch?v=dCSIXLIzhzk
IMO Oumuamua was a rock.
However, it's fun to think about it being alien, and it's remarkably similar to Arthur Clarke's Rama story.
Presumably the speed and trajectory of Oumuamua is known? Has this been traced back to give a potential origin if it is fro another star system?
"Two of NASA's space telescopes (Hubble and Spitzer) tracked the object traveling about 85,700 miles per hour (38.3 kilometers per second) relative to the Sun. Its outbound path is about 20 degrees above the plane of planets that orbit the Sun." https://solarsystem.nasa.gov/asteroids-comets-and-meteors/co...
If the distance to the nearest star is 40,208,000,000,000 then:
40,208,000,000,000 / 38 (km per second) / 3600 seconds per hour / 24 hours per day 365 days per year = 33552 years if it had come from closest star
Do I have those numbers right? Maths isn't a strength.
One of the arguments for Oumuamua being more than just a "rock" was its detected dimension. If I recall correctly, it was very long and skinny and thus not very rock-like in a traditional sense. I think Avi Loeb put forth the idea that structurally an object like this could be a a piece of space junk. Maybe a piece of a space ship that would be able to be held together while spinning even with a long and skinny dimension. You'd imagine less stable pieces of rock to collapse into themselves and become more sphere like. Oumuamua was potentially a long skinny object that had been spinning around through the universe for a very long time.
The impossibility of interstellar travel is perhaps the only fact that I find so depressing that I simply refuse to believe it. The universe is just so much more interesting if FTL is possible. It helps that being wrong about this fact doesn't really impact one's life either way.
Okay, then I'll cheer you up just a bit: interstellar travel is quite possible. In fact it's easy... if you can cold hibernate.
It would be very easy for an AI that could simply turn itself off for tens of thousands of years. It might be a do-able for an alien biological entity with a different biology that finds it easier to survive cryogenic deep freeze, something like a big smart tardigrade.
Managing sleep and wake is pretty easy too. No internal timing mechanisms needed. Just let your proximity to a star do it for you. When you leave the vicinity of a star you have no energy and you go night-night. Your temperature will fall down to as low as a few kelvin. This basically stops time in terms of any chemical degradation, though the most sensitive bits will need to be wrapped in radiation shielding against cosmic rays to prevent cumulative damage over the aeons. When you approach another star the temperature starts to go up and solar power will power everything up.
Interstellar travel is only hard for us because we have short life spans and can't survive being frozen. Unless we can figure out how to successfully freeze a human down to liquid helium temperatures and then revive them it's unlikely that humans will ever leave the solar system.
The AIs we build might though. This would include "uploaded" minds if we ever figure out how to do that.
If anything ever does visit us my money would be on it being an AI.
If you find humans being stuck in the solar system depressing, consider that the solar system is absolutely gigantic and we could explore and settle it for aeons and aeons without getting close to exhausting that frontier.
Imagine a religious order like the space Mormons in the Expanse creating a self replicating evangelism bot. A few billion years later nothing in the galaxy with more brain power than a mouse can get through life without being asked if it wants to hear about another testament of Jesus Christ.
We do help seed millions of other advanced civilizations though since when they become smart enough they are able to learn a ton by reverse engineering some of the millions of dead probes littering their planet and every other celestial body. Their first messages into the cosmos are variations of “okay which one of you bastards did this?”
Nobody is ever able to figure out the meaning of the probe’s message and humanity is long extinct.
Not meaning to diss Mormons though. If anyone built a generational ship I can imagine them doing it.
You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space. ~ Douglas Adams
A nice visualisation I like to use is this: if the orbit of the Earth was scaled down to the size of a coin, then the average distance between stars is about a mile.
And yet we pretty much have the technology right now to send a probe to Alpha Centauri. The Parker Solar Probe would make it there in about 8000 years. We could probably make a probe that makes it there in much less time if we wanted (by taking much longer to accelerate and de-accelerate). Then it just needs to survive a few thousand years dormant.
Not interstellar, but I leave near Sunspot, New Mexico. Since lots of schools visit the sunspot observatory there they have a series of signs starting with Neptune at the beginning of the road (Highway 6563 for those interested) and ending with the sun at the observatory. The signs are spaced proportionally over the 15 mile road and it amazing how close mars -> sun all are compared to the rest, and that doesn't even deal with the rest proxima centauri (I'm curious where that would actually be, Colorado?)
I suppose its possible that humans could exist for hundreds of millions of years? If so then several hundred thousand years robot probe missions might make sense.
Interstellar travel would be possible if we learn how to manipulate consciousness and then transport consciousness as data using light. The first part may be accomplished without continuity for the original but as a seamless experience for the copy.
Looks good to me as a rough back-of-the-envelope calculation to get the orders of magnitude right (the speed will go down as the object is climbing out of Sun's gravity well).
However, you're still missing a guesstimate for alien lifespan. Do you have reasons to believe they live shorter than 33552 Earth years?
Also, is 38 km/s really the top speed for hypothetical interstellar ship?
I imagine aliens that live on average 870 Earth years (~10x average lifespan of a female Japanese) and travel at 9,000 km/s. They can easily make Sun-Proxima Centauri trip six times in a lifetime.
Interstellar travel is entirely in the realm of possibility for the future. I'd even call it likely. We'll have to wait a few centuries probably, but we'll do it unless we get derailed or extinct.
On the other hand there are theories around how many alien civilizations there are and there are probably not many if at all. Basically we are "early" and there is probably no other civilization in the milky way.
The galaxy isn't static. Sure, right now the nearest star is more than 4 light years away, but wait around a few million years. You'll get stars passing within a fraction of a light year.
But I don't believe in interstellar travel at all. I don't think people grasp the distances between stars. The longest distance a human has traveled through space is to the moon. If, for scale, this was about 2 millimeters, then the nearest star would be another 200 kilometers/124 miles away. Here's a great video to illustrate https://www.youtube.com/watch?v=dCSIXLIzhzk
IMO Oumuamua was a rock.
However, it's fun to think about it being alien, and it's remarkably similar to Arthur Clarke's Rama story.
Presumably the speed and trajectory of Oumuamua is known? Has this been traced back to give a potential origin if it is fro another star system?
"Two of NASA's space telescopes (Hubble and Spitzer) tracked the object traveling about 85,700 miles per hour (38.3 kilometers per second) relative to the Sun. Its outbound path is about 20 degrees above the plane of planets that orbit the Sun." https://solarsystem.nasa.gov/asteroids-comets-and-meteors/co...
If the distance to the nearest star is 40,208,000,000,000 then:
40,208,000,000,000 / 38 (km per second) / 3600 seconds per hour / 24 hours per day 365 days per year = 33552 years if it had come from closest star
Do I have those numbers right? Maths isn't a strength.