Just a few weeks ago New Horizons was doing a flyby of kuiper belt object Ultima Thule. Before the flyby, this object was merely a couple of pixels in any of our instruments.
In fact, it exhibited odd light curves that seemed very unlikely for a regular asteroid. This also prompted comparisons to Rama, just like Oumuamua did. Its straight out of the book.
So up until the first pictures were downloaded, we definitely did not have enough data to disprove an alien artifact hypothesis. Turned out to be just another asteroid (a pretty interesting one, but no green men)
Ultima Thule was a studied object, targeted by an serious AF NASA interplanetary mission, and we knew jack shit about it. There are millions of other kuiper belt objects out there and we know absolutely nothing about them.
So yeah, Oumuamua is pretty much part for the course in that regard.
"The most unusual fact about it is that it deviates from an orbit that is shaped purely by the gravitational force of the sun. Usually, in the case of comets, such a deviation is caused by the evaporation of ice on the surface of the comet, creating gases that push the comet, like the rocket effect. That’s what comets show: a cometary tail of evaporated gas. We don’t see a cometary tail here, but, nevertheless, we see a deviation from the expected orbit. And that is the thing that triggered the paper. Once I realized that the object is moving differently than expected, then the question is what gives it the extra push. And, by the way, after our paper appeared, another paper came out with analysis that showed very tight limits on any carbon-based molecules in the vicinity of this object."
Most of these comments are arguing against a claim that has not been made.
> "It is much more likely that it is being made by artificial means, by a technological civilization."
"if it is indeed less than a millimetre thick, if it is pushed by the sunlight, then it is maybe a light sail"
It's not clear at all that he think it's likely that it's less than a millimeter thick or that it is a light sail. That's simply "the only thing that came to his mind" to explain the additional force(s) working on it.
> The following October, Avi Loeb, the chair of Harvard’s astronomy department, co-wrote a paper (with a Harvard postdoctoral fellow, Shmuel Bialy) that examined ‘Oumuamua’s “peculiar acceleration” and suggested that the object “may be a fully operational probe sent intentionally to Earth’s vicinity by an alien civilization.”
or another spot where he says
"Every now and then we find an object of artificial origin. And this could be a message in a bottle, and we should be open-minded."
Seems to me like he is saying it could be worth considering that maybe this is an alien object.
> Man that food sure looks tasty.
> You haven't even tasted it! Why are you saying it's tasty?
There are absolutely no claims that it's an alien artifact. What he is doing is providing reasons for why checking out similar solar visitors is something we need to do.
Likely: greater than 50% probability
Possibly: greater than 0% probability
Saying something is likely is a pretty strong claim. You can make meaningful decisions based on such knowledge.
Given extremely ambiguous information, the chance of something like Oumuamua being an alien probe depends very strongly on the chance of an alien civilization producing something like this. And those chances are beyond anyone knowing. The Bayesian priors are just unguessable.
All of those things are easily explained by it having formed at the same time as the other Kuiper objects formed and in the same way. It makes it significantly unlikely that it flew in from far away, decelerated into orbit in the Kuiper belt, and then changed its orbit to match the ecliptic.
And even though it was but a few pixels, by calculating its mass using its orbital parameters its density can be deduced to be similar to other belt objects (rock and ice rather than metals). Which further enhances the 'its a normal object' hypothesis.
It is possible of course, that an alien civilization designed a probe that would mimic the composition of a Kuiper belt object and flew it here, and then inserted it into its orbit, and then flew away, so that it could sit there and do what ever it does. But that is not the most likely answer :-)
> Ultima Thule was a studied object, targeted by an serious AF NASA interplanetary mission...
Sadly for Oumuiamua, this thing was detected far too late to do intensive observations, it's on the way out of the solar system if I understand correctly.
Another interesting point is that if it is an alien probe it would have had to been sent long before human civilization began unless the aliens are parked practically on our doorstop.
When Voyager 1 and 2 fly through some distant star system millennia from now, it will be pretty clear they aren't space junk. But it is also true that our species will no longer exist either.
I base that on the following conjecture, if we were to become capable of travelling among the stars with relative ease, then we'll go collect these two little artifacts and put them in a museum. But if we go extinct, these ships will continue on their way forever. So any alien that comes across them can know we're extinct.
That seems like the height of human hubris - we are stuck on a little rock in the corner of the galaxy, but somehow assume we are authorities on things astronomical.
> I base that on the following conjecture, if we were to become capable of travelling among the stars with relative ease, then we'll go collect these two little artifacts and put them in a museum. But if we go extinct, these ships will continue on their way forever. So any alien that comes across them can know we're extinct.
You're assuming that we will at some point have the ability to catch up to them - we may develop interstellar flight, but it may be stuck in very slow speeds, we may never catch up to them with our giant colony ships as we sleep away the eons.
The basic idea of science is that it's possible to do better than "assume we are authorities..." I don't want to come across as unsocial but in dismissing astronomy without knowing enough about it you may be guilty of some hubris yourself.
Now instead of collecting them, we will mostly build a mobile museum, to show the then humans, achievements of early humans, still moving through space.
Eventually we will get so advanced we wont really worry about collecting them at all, for the same reasons, the current humans don't go looking for the first wheel ever made.
Are you talking about Terran homosapiens specifically and the consideration that once we populate other planets that we'll become genetically different enough to no longer be considered the same species - or do you think we'll never get up there?
First we know there are many ways in which life on the planet can be eradicated that are not yet preventable by humans. Asteroid impact, solar flare, volcanic eruption, and climate change, while humans also can kill ourselves off with a large exchange of nuclear weapons. So if you plot the chance of our existing over time, as long as we stay a single planet species that plot heads to zero long before Voyager interacts with another star system.
Then we have Voyager, which will take 17 thousand years (and some change) to go one light year. Nearest star system is Alpha Centauri at just over 4 light years away so conservatively 80 thousand years before Voyager gets there (assuming it is on a path that takes it to Alpha Centauri)
Doing the math, the probability that humans exist in 80 Kyrs versus human ability to travel at a significant speed (say > 0.5c) between the stars vs human nature to retain artifacts when they can from historic events.
It is a thought exercise, which I doubt we'll live to see any affirmative answer to :-)
Andromeda, one of our closest galactic neighbors is 220,000 light years away.
Imagining that Voyager 1 is going in the right direction and ignoring that the Andromeda is going to collide with us regardless, that works out to 3,821,000,000 years to get there. And that's for a very very close galaxy, on an astronomical scale.
Pretty optimistic to think we'll be around on that time scale, but I suppose it could happen.
Moot point for Andromeda since that's coming here, but it'll never ever get to any other galaxies.
After that, it gets a little difficult to predict Voyager's journey, as chaotic motions within the galaxy make accurate predictions of stellar movements challenging. But given the wide swaths of empty space between the stars, the spacecraft's visit near Gilese 445 is probably the closest that Voyager 1 will approach another star, ever."
https://www.space.com/39161-fate-of-the-voyager-spacecraft.h...
>Is it necessarily true that our species will not exist when Voyager 1 and 2 fly through in a galaxy far far far away a long long time in the future?
Saying that is an alien probe it's not an argument, just an untested hypothesis. What follows on the paragraph is an argument, albeit a bad one.
This is nonsense. Every claim has an corresponding claim of its negation. Which one has the burden of proof?
What evidence do you have that it's an asteroid?
The burden of proof is on the latter, this is just SoP in science. Otherwise we end up with a world full of superstition, as it was for most human history.
We have no evidence yet of other intelligent life in the universe. But we know there are quadrillions of asteroids all over the place, some of which pass by us every so often.
Occam's razor, correctly stated, says that, all else equal, the explanation that relies on the fewest assumptions is most likely the true one. Given our lack of evidence for intelligent life, and preponderance of evidence of asteroids, the former explanation requires far more assumptions than the latter.
It is also not a comet, so the null hypothesis is that it’s a rocky natural object but it doesn’t mean it’s an asteroid.
The best classification we might have for it is a distant detached object (DDO) but since it’s likely not part of our solar system it can’t be classified as a detached object by the current minor planetary object classification system we have either.
In most cases the "claim of negation" is the default position (related to the null hypothesis). If I claim there are invisible faeries that hold us to the earth. The negation of that claim is that there aren't. But this sort of reasoning only applies to things like debate and philosophy.
Science is fine with the unknown, claims must meet the burden of proof to be considered more than a speculation. Hence a "claim of negation" isn't scientific, because you instead present observation and calculation which makes the claim invalid in the first place. The default state being that no claim (we call these hypothesis) is valid. Sometimes this means that there are many competing partially valid hypothesis. One can't prove a negative, so instead science deals in hypothesis and only ever judges the positive claim against what we know. I can't emphasize this enough, there is no such thing as a negative claim in science: just a claim that we don't know the answer yet because no current hypothesis are convincingly valid.
People aren't claiming it's an asteroid, because that has a specific definition it doesn't match. Note in the article he talks about comets as one thing some people think it is. In the title of the article it's "Interstellar Object" which I don't think anyone is disputing.
The hypothesis he is putting forward is reasonable though. At least as well as any other hypothesis. We don't really have proof (observations) either way (and like a good scientist he spends a lot of time pointing out how we should be ready next time) so no hypothesis can meet a burden of proof at the moment. But then science doesn't really use a concept of "burden of proof", that's a legal concept. Instead we simply work with our least wrong models - even our best theories are not proven - which are judged by how well they predict the world.
And in this example the hypothesis "aliens did it" answers a lot of questions in a reasonable way. But then so does "nature did it" but some of the answers and mechanisms are less convincing in that case. And I think the point the interviewee is making is that we should be ready to better answer that question next time an object like this comes by because the answer "nature did it" is somewhat unconvincing for this object.
Suppose I show you a jar containing a large number of coins and I claim the number of coins is even by just looking at the jar. Do you have evidence that I am correct? No! Just by looking at it I can't possibly know the exact number of coins. But this means that the logical negation of my claim is true ( the number of coins is odd?). Also no! Again, I can't know the exact number of coins by just looking at it.
So although there are only two possibilities, I have no evidence at all. And this means the only claim I can make is the null hypothesis: I don't know.
Absence of evidence is not, itself, an evidence of absence. In other words, if I don't have evidence that you committed a murder, it doesn't mean you're innocent. It means just that: I don't have evidence to convict you, and I must dismiss the case.
Secondly, science doesn't prove. It creates models, and finds the ones that stand up to close scrutiny. Bretz provided massive evidence for his flood model. Those who chose to ignore him chose to ignore the evidence ... whatever their names were.
The one making ANY claim has the burden of proof. The null hypothesis is the default whenever there's no evidence supporting any claim. It is basically a fancy way of saying we don't know what it is.
It's much more likely that it's ejecta from some event from outside our solar system. Or a redirected Oort body.
This is why the Occam's razor rule is important. He formulate a (weird) hypothesis, he thought 3 or 4 ways to prove that the hypothesis is false, then he failed to prove that the hypothesis is false. Then the conclusion is???
The possibilities are:
* A weird asteroid
* A disabled alien probe
* A functional alien probe
* Something more weird
All four variants have almost the same level of support now. But using the Occam's razor we should favor the first one until more evidence is discovered.
Imagine our best understanding of cosmology suggested that some interstellar object, which we'll call "foobars" for the sake of this argument, existed in high amounts. However, we weren't totally certain that foobars existed, or exactly what they would look like if they did.
In this case, when we discovered a new, weird and unexplainable phenomenon, would there really much pushback when somebody proposed that foobars might be the cause?
Well, according to the Fermi Paradox[1], there's seems to be a very good chance, statistically speaking, that alien life is common in our galaxy. So, when a phenomenon is observed with highly unusual characteristics, why should an alien origin be considered unlikely or fringe explanation?
I think people dismissing or diminishing the possibility of an alien explanation should also be required to provide a reasonable, evidence-based explanation for the Fermi Paradox.
If confirmed, which of the following two will get to the first page of all newspapers in the world:
* Scientists find a rock in space
* Scientists find a alien starship in space
The "default" selection is the other, unless someone provides overwhelming evidence.
> In this case, when we discovered a new, weird and unexplainable phenomenon,
It's probably a rock with some ice.
> Well, according to the Fermi Paradox,
The Fermi paradox starts from the assumption that we should expect a big number of advanced civilization in the Milky Way, but we really don't have the smallest cue about how the number should be. We have a estimations from millions of millions to much less than one. We just don't know. We only know that we didn't find an alien civilization yet. We didn't even find alien life yet. So you can't use the Fermi paradox as a proof or supporting evidence that an unknown object has alien origin.
I highly recommend the PBS Space Time video on this topic linked in another comment.
Why not? Assuming a civilization is (or was) technologically advanced enough, they would probably be doing lots of things we couldn't understand, especially given how little we know about this thing. He wasn't saying it was definitely, or even probably, a light sail, just that we should entertain the possibility.
Besides, we don't actually know what the shape is, only that its changes in brightness would be consistent with an elongated object, which is the simplest explanation. Or, maybe the object is perfectly spherical but the brightness changes are due to seeing a light sail at different angles, which is extremely unlikely but within the realm of possibility.
We can barely see Ultima Thule as a pixel, which is closer, and the size of a city. Voyager is the size of a pinto.
What would be that private company's incentive?
There are many projects I can't wrap my head around due to the great costs. When I suggest we should not spend trillions on going to mars without having a specific need to do so, people reject that notion.
How the heck do we know that? We have no idea what "alien technology" might be or what the result of it might look like.
The argument I've heard is that it is a disabled alien probe. This makes sense given that any device sent into space will probably last much longer as space junk than as a working device. So, the density of alien space junk would be higher than the density working artifact. Thus, if this thing were to turn out to be disabled alien probe, it would be more or less what you'd expect to see occasionally if alien civilizations of our level existed in some moderate density (note, most of "Fermi Hypothesis" possibility arguments involves hypothetical higher levels of civilization, which seems to me a rather thin argument).