Object that passed by Earth *probably* came from Alien World, Harvard professor says

[Ripster42]

I don’t find any objections to life existing anywhere else in the universe particularly meritorious. That we don’t have direct evidence of it existing doesn’t mean we can’t extrapolate that it likely does.

We don't have any evidence at all, direct or otherwise, as to the frequency of life. We only have one data point. You've already admitted you're biased, in this thread:

I certainly err on the side of "what's to say it doesn't exist?"

You're not a reliable arbiter.

I'm certainly not claiming there's not other origins of life out there. I'm saying, very correctly, that we do not have enough data to speculate with any expectation that our speculations match reality. Your entire argument is specious. A single data point will never be enough for a frequency test. "A sense of wonder," which is what your argument boils down to, isn't a good thesis. I get it, it's fun to dream, but it is not, as you claim, "in essence, true."

[Kaleredar]

We don't have any evidence at all, direct or otherwise, as to the frequency of life. We only have one data point. You've already admitted you're biased, in this thread:



You're not a reliable arbiter.

I'm certainly not claiming there's not other origins of life out there. I'm saying, very correctly, that we do not have enough data to speculate with any expectation that our speculations match reality. Your entire argument is specious. A single data point will never be enough for a frequency test. "A sense of wonder," which is what your argument boils down to, isn't a good thesis. I get it, it's fun to dream, but it is not, as you claim, "in essence, true."

And, like I said, while I might not be an astrophysicist, most of them... whom we should probably think as "fairly reliable arbiters" as to the nature of the universe as we understand it, seem to think that life likely exists elsewhere in the universe.

Our data point of one isn't something we know nothing about. How life formed on earth is not some vague mystery. We know the conditions it was formed in. We know the elements it was formed from. We know the distance of the planet it formed on from the star that it formed around. And we find these conditions elsewhere in the universe.

[Ripster42]

And, like I said, while I might not be an astrophysicist, most of them... whom we should probably think as "fairly reliable arbiters" as to the nature of the universe as we understand it, seem to think that life likely exists elsewhere in the universe.

Our data point of one isn't something we know nothing about. How life formed on earth is not some vague mystery. We know the conditions it was formed in. We know the elements it was formed from. We know the distance of the planet it formed on from the star that it formed around. And we find these conditions elsewhere in the universe.

And we have absolutely no idea how often those conditions lead to the generation of life besides, "At least once in all of existence."

[Kaleredar]

And we have absolutely no idea how often those conditions lead to the generation of life besides, "At least once in all of existence."

And what would cause us to think this could only happen once? Where is your proof-negative, here?

All of the things that we know are causes of life we know to exist elsewhere, within circumstances very similar to those on earth. We find and can theorize the existence of planets with ever increasingly-similar properties to that of earth. Endus noted the potential critical role the tidally-locked moon might have played in the development of life, to which I noted that we have evidence of the exact same circumstances that created earth's moon having happened to other celestial bodies within just our solar system.

The only real argument you have to stake your claim on is, fundamentally, that "absence of evidence must be taken to mean evidence of absence, and because of that we can make no predictions."

[Ripster42]

And what would cause us to think this could only happen once? Where is your proof-negative, here?

There is nothing. I've been clear. We have no evidence one way or the other. None. One data point does not give us enough information.

[Endus]

But on that same token we have the otherwise "exceptional" planet of Uranus that spins on its side because it, too was likely impacted by an enormous celestial body (thought to be roughly the size of earth) that tilted it so heavily. It's also theorized that this impact in Uranus' history also helped create a number of its moons.

It isn't that there was an impact, it's the specific manner of that impact. With Uranus, it did not create an overly-massive moon, and the plane of rotation is so borked that it would likely render a terrestrial planet inhospitable all by itself.

Pluto and Charon are tidally locked, and Charon is thought to have formed in a similar manner to how Earth's moon formed: an enormous impact event tearing off a chunk of Pluto's crust.

Pluto lacks the magnetosphere component. It's not the rarity of any one factor, it's the rarity of it all occurring in the correct sequence and to the correct degree to the right kind of planet under the right kind of star.

And that, of course, presupposes that a tidally-locked moon in the exact same form as earth's moon is A-1 critical to life.

It's stabilized our "wobble" significantly, leading to the reliable pattern of seasons. Smaller moons wouldn't have enough effect to achieve that, and without it, the wobble would cause conditions to vary enough to make life's long-term survival unlikely.

But this is all, of course, speculation, since we're operating off a single data point. I was just making the point that the Drake Equation stuff usually omits about eleventy billion factors.

[Daedius]

It's the bugs throwing asteroids at us!

[PC2]

We don't have any evidence at all, direct or otherwise, as to the frequency of life.

Yeah barely anything is known about how easy or hard is for life to get started. In order to make some progress on that we would need to discover the sequence of molecules and transformations that lead up to RNA/DNA and its machinery. If we don't even know much about the catalysts of life on Earth then we certainly can't talk about its frequency on other planets.

[Kaleredar]

It isn't that there was an impact, it's the specific manner of that impact. With Uranus, it did not create an overly-massive moon, and the plane of rotation is so borked that it would likely render a terrestrial planet inhospitable all by itself.



Pluto lacks the magnetosphere component. It's not the rarity of any one factor, it's the rarity of it all occurring in the correct sequence and to the correct degree to the right kind of planet under the right kind of star.

Well, the formation of moons via substantive impact event, even moons that are consequently large in size to the original body and create a tidally locked moon, is certainly not a rarity, having happened three times in the same solar system in the case of the former and twice in the case of the latter. And again, that's within the timeframe that our solar system has existed, with the age of the universe being many times older than that.

It would likely be errant to say something as concrete as "including the eight planets in our solar system and the five dwarf planets, we can conclude that 3/13 planets undergo significant planetary collisions in their formations, and that 2/13 planets have these cause the creation of a significantly sized, tidally-locked moon." But from what we've seen within our own solar system, it certainly doesn't paint a picture of it being particularly rare, unless you want to suppose that our little solar system is phenomenally lucky to have multiples of all of these events happening.

It's stabilized our "wobble" significantly, leading to the reliable pattern of seasons. Smaller moons wouldn't have enough effect to achieve that, and without it, the wobble would cause conditions to vary enough to make life's long-term survival unlikely.

And yet mars still has extant and predictable seasons without the tidally locked moon earth has.

But this is all, of course, speculation, since we're operating off a single data point. I was just making the point that the Drake Equation stuff usually omits about eleventy billion factors.

I'm not particularly relying on the drake equation here, I'm simply going off of a more general analysis of the factors that lead to life on earth, and those factors not, in it of themselves, being particularly exceptional within the universe.

We can observe many of these sorts of "prexisting factors" within our own solar system. If these things can piecemeal happen many different times within a data set you can count on your fingers and toes, I see no reason that then recombining those factors by an order of many quintillions wouldn't logically recreate arbitrarily similar results.

[Utinil]

We can definitively say there is no life in the universe. It has been proven by sound logic in one of the best books ever written.

Population: None. Although you might see people from time to time, they are most likely products of your imagination. Simple mathematics tells us that the population of the Universe must be zero. Why? Well given that the volume of the universe is infinite there must be an infinite number of worlds. But not all of them are populated; therefore only a finite number are. Any finite number divided by infinity is zero, therefore the average population of the Universe is zero, and so the total population must be zero.

[cubby]

No because that’s not how science works. I mean it could be a giant fucking space unicorn.

Except it isn’t because we don’t know that or have any evidence it’s anything.

So it’s fine to say we do not know just as it’s fine to say it’s not aliens or space unicorns.

Because not knowing what it is in science does mean make shit up. Which is what happened here

It was my understanding that there was evidence that the object speeded up as it headed out of our solar system, over and above the delta-v that would have resulted from rounding the sun.

[Ashleyxoxo]

Excuse yourselves, he is from Harvard.

[Kaleredar]

It was my understanding that there was evidence that the object speeded up as it headed out of our solar system, over and above the delta-v that would have resulted from rounding the sun.

It’s thought that the object was likely a loose string of meteors bound together weakly by gravity and a common trajectory. If this amalgam contained ice, it would begin to melt as it passed near the sun, sublimating the ice off into space. This would cause a decrease in mass and therefore an increase in velocity, accounting for the object seemingly “speeding up”

[cubby]

It’s thought that the object was likely a loose string of meteors bound together weakly by gravity and a common trajectory. If this amalgam contained ice, it would begin to melt as it passed near the sun, sublimating the ice off into space. This would cause a decrease in mass and therefore an increase in velocity, accounting for the object seemingly “speeding up”

I thought that merely losing mass wouldn't speed up an object. Or am I missing the full picture, that it's the combination of losing mass combined with a sling shot around the sun that would speed it up? And we didn't have a lot of information about it to begin with because of it's speed and (relative) small size and distance to us.